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A Transport Technology for Nanowires Thermally Treated at 700 Celsius Degrees
Professor Jun-Bo Yoon and his research team of the Department of Electrical Engineering at KAIST developed a technology for transporting thermally treated nanowires to a flexible substrate and created a high performance device for collecting flexible energy by using the new technology.
Mr. Min-Ho Seo, a Ph.D. candidate, participated in this study as the first author. The results were published online on January 30th in ACS Nano, an international journal in the field of nanoscience and engineering. (“Versatile Transfer of an Ultralong and Seamless Nanowire Array Crystallized at High Temperature for Use in High-performance Flexible Devices,” DOI: 10.1021/acsnano.6b06842)
Nanowires are one of the most representative nanomaterials. They have wire structures with dimensions in nanometers. The nanowires are widely used in the scientific and engineering fields due to their prominent physical and chemical properties that depend on a one-dimensional structure, and their high applicability.
Nanowires have much higher performance if their structure has unique features such as an excellent arrangement and a longer-than-average length. Many researchers are thus actively participating in the research for making nanowires without much difficulty, analyzing them, and developing them for high performance application devices.
Scientists have recently favored a research topic on making nanowires chemically and physically on a flexible substrate and applies the nanowires to a flexible electric device such as a high performance wearable sensor.
The existing technology, however, mixed nanowires from a chemical synthesis with a solution and spread the mixture on a flexible substrate. The resultant distribution was random, and it was difficult to produce a high performance device based on the structural advantages of nanowires. In addition, the technology used a cutting edge nano-process and flexible materials, but this was not economically beneficial. The production of stable materials at a temperature of 700 Celsius degrees or higher is unattainable, a great challenge for the application.
To solve this problem, the research team developed a new nano-transfer technology that combines a silicon nano-grating board with a large surface area and a nano-sacrificial layer process. A nano-sacrificial layer exists between nanowires and a nano-grating board, which acts as the mold for the nano-transfer. The new technology allows the device undergo thermal treatment. After this, the layer disappears when the nanowires are transported to a flexible substrate.
This technology also permits the stable production of nanowires with secured properties at an extremely high temperature. In this case, the nanowires are neatly organized on a flexible substrate. The research team used the technology to manufacture barium carbonate nanowires on top of the flexible substrate. The wires secured their properties at a temperature of 700℃ or above. The team employed the collection of wearable energy to obtain much higher electrical energy than that of an energy collecting device designed based on regular barium titanate nanowires.
The researchers said that their technology is built upon a semiconductor process, known as Physical Vapor Deposition that allows various materials such as ceramics and semiconductors to be used for flexible substrates of nanowires. They expected that high performance flexible electric devices such as flexible transistors and thermoelectric elements can be produced with this method.
Mr. Seo said, “In this study, we transported nanowire materials with developed properties on a flexible substrate and showed an increase in device performance. Our technology will be fundamental to the production of various nanowires on a flexible substrate as well as the feasibility of making high performance wearable electric devices.”
This research was supported by the Leap Research Support Program of the National Research Foundation of Korea.
Fig. 1. Transcription process of new, developed nanowires (a) and a fundamental mimetic diagram of a nano-sacrificial layer (b)
Fig. 2. Transcription results from using gold (AU) nanowires. The categories of the results were (a) optical images, (b) physical signals, (c) cross-sectional images from a scanning electron microscope (SEM), and (d-f) an electric verification of whether the perfectly arranged nanowires were made on a large surface.
Fig. 3. Transcription from using barium titanate (BaTiO3) nanowires. The results were (a) optical images, (b-e) top images taken from an SEM in various locations, and (f, g) property analysis.
Fig. 4. Mimetic diagram of the energy collecting device from using a BaTiO3 nanowire substrate and an optical image of the experiment for the miniature energy collecting device attached to an index finger.
2017.03.22 View 9440 -
Professor Kwangjo Kim Named as Fellow of IACR
Professor Kwangjo Kim of the Graduate School of Information Security has been selected as a fellow of the International Association for Cryptologic Research (IACR).
The IACR has honored outstanding scholars who have achieved academic excellence in cryptologic research since 2004. He is the first Korean scholar to receive an IACR fellowship.
The IACR, established in 1981, is responsible for organizing international cryptologic conferences every year including the three major cryptologic academic conferences Eurocrypt, Crypto, and Asiacript. The IACR also sponsors workshop series such as the Theory of Cryptography Conference (TCC), the Workshop on Fast Software Encryption (FSE), the Public Key Cryptography Workshop (PKC), and Cryptographic Hardware and Embedded Systems (CHES).
Professor Kim, an internationally acclaimed scholar in the fields of cryptology and information security theory and its applications, was recognized for his outstanding academic achievements and leadership. He has made significant contributions to cryptology in Korea by hosting Asiacript in 1996 and 2001 as well as CHES in 2014. During his 34 years of academic activities, he has published more than 80 SCI journal papers and garnered more than 20,000 citations.
Professor Kim served on the board of the directors of the IACR from 2000 to 2004 and was the chairperson of the Asiacript Steering Committee from 2005 to 2008. He is on the editorial board of the online journal Cryptography.
Professor Kim said, “I am so humbled and honored to be named as a fellow of such a prestigious academic association. I will continue to strive to assist highly educated information security personnel with further research in cryptology.”
2017.03.16 View 8494 -
6 Subjects of KAIST Ranked in the Top 20 in the World
Six disciplines of KAIST have emerged among the top 20 in the world. The 2017 QS World University Rankings by Subject rated Materials Science at KAIST 13th in the global ranking. Other subjects ranked within top 20 include Chemical and Biomolecular Engineering (15th), Civil and Environmental Engineering (15th), Mechanical and Aerospace Engineering (15th), Electrical Engineering (17th), and Chemistry (18th). This year, two more disciplines advanced into the top 20 from four in 2016.
QS ranked KAIST as the top science and technology research university in Korea. KAIST earned the highest global rankings among Korean universities in the following seven areas: Materials Science and Engineering (13th), Chemical and Biomolecular Engineering (15th), Civil and Environmental Engineering (15th), Mechanical and Aerospace Engineering (15th), Electrical Engineering (17th), Chemistry (18th), and the School of Computing (33th). In addition, two more disciplines of Physics (44th) and Mathematical Sciences (47th) were ranked second among domestic universities.
The London-based university ranking by Quacquarelli Symonds, Ltd. announced the global university ranking by 46 subjects on March 8. QS rankings are based on academic reputation, employer reputation, the number of research citations, and research accomplishment index (H-index).
2017.03.09 View 5220 -
13 KAIST Faculty Named as Inaugural Members of Y-KAST
The Korean Academy of Science and Technology (KAST) launched the Young Korean Academy of Science and Technology (Y-KAST) and selected 73 scientists as its inaugural members on February 24. Among them, 13 KAIST faculty were recognized as the inaugural members of Y-KAST.
Y-KAIST, made up of distinguished mid-career scientists under the age of 45, will take the leading role in international collaboration as well as innovative agenda-making in science and technology.
The inaugural members include Professor Hyotcherl Ihee of the Department of Chemistry and Dr. Sung-Jin Oh of the Center for Mathematical Challenges at the Korea Institute for Advanced Study (KIAS), affiliated with KAIST. Professor Ihee is gaining wide acclaim in the fields of physics and chemistry, and in 2016, Dr. Oh was the youngest ever awardee of the Presidential Award of Young Scientist.
The other Y-KAIST members are as follows: Professors Haeshin Lee of the Department of Chemistry; Mi Young Kim, Byung-Kwan Cho, and Ji-Joon Song of the Department of Biological Sciences; Song-Yong Kim of the Department of Mechanical Engineering; Sang-il Oum of the Department of Mathematical Sciences; Jung Kyoon Choi of the Department of Bio and Brain Engineering; Seokwoo Jeon, Sang Ouk Kim, and Il-Doo Kim of the Department of Materials Science and Engineering; Jang Wook Choi of the Graduate School of EEWS (Energy, Environment, Water and Sustainability); and Jeong Ho Lee of the Graduate School of Medical Science and Engineering.
The leading countries of the Academy of Science, which include Germany, Sweden, Belgium, Canada, and Japan, have established the Young Academy of Science since 2010 in order to encourage the research activities of their young scientists and to establish a global platform for collaborative research projects through their active networking at home and abroad.
President Myung-Chul Lee of KAST said, “We will spare no effort to connect these outstanding mid-career researchers for their future collaboration. Their networking will make significant impacts toward their own research activities as well as the global stature of Korea’s science and technology R&D.
(Photo caption: Members of Y-KAST pose at the inaugural ceremony of Y-KAST on February 24.)
2017.03.02 View 17961 -
A KAIST Alumnus Receives the Marie Sklodowska-Curie Individual Fellowships
Dr. Je-Kyung Ryu, a graduate of the Physics Department at KAIST in 2014, received the 2017 Marie Sklodowska-Curie Individual Fellowship.
Established in 1996, the Marie Sklodowska-Curie Individual Fellowships support young scientists in or outside Europe to help them grow as independent researchers. The recipients are recognized to have the highest potential to make a difference in science and technology and work on research and innovation.
Dr. Ryu is currently working as a postdoctoral researcher at the Cees Dekker Lab in the Department of Bionanoscience at the Kavli Institute of Nanoscience at Delft University of Technology (TU Delft), Netherlands.
He was among six international researchers at TU Delft who were awarded this research grant.
The grant of 177,000 euros will be offered for two years from March 2017 to February 2019 to cover his salary and research expenses.
For a news article published by TU Delft on the award, please click below:
QN and BN Successfully Attract Young Scientific Talent
February 1, 2017
2017.02.22 View 6874 -
Dr. Sung-Chul Shin Selected 16th President of KAIST
(President Sung-Chul Shin)
The KAIST Board of Trustees elected Professor Sung-Chul Shin of the Department of Physics the 16th president of KAIST on February 21. Professor Shin succeeds President Sung-Mo Kang whose four-year term will end on February 23. He is the first KAIST alumnus to serve as its president.
The Board of Trustees announced, “We believe that Professor Shin’s scientific achievement, outstanding leadership, and clear vision will serve KAIST faculty, students, and staff very well. He will be the best person to help KAIST leap forward in the four years ahead.”
The newly-elected president said, “I am humbled and honored to have been elected to lead such a prestigious institute of Korea. Aiming to be one of the top ten global universities, KAIST will continue to innovate its systems.” Previously, Dr. Shin led the Daegu Gyeongbuk Institute of Science and Technology (DGIST) for six years as president since 2011.
Professor Shin joined the KAIST faculty in 1989. He graduated from Seoul National University and then earned his MS degree in condensed matter physics at KAIST in 1977. After earning his Ph.D. in material physics at Northwestern University in 1984, he worked at Eastman Kodak Research Labs as a senior research scientist for five years.
Before heading to DGIST, President Shin held key administrative positions at KAIST from the early 1990s including dean of planning, dean of the international office, and vice-dean of student affairs. During President Robert Laughlin’s tenure, the first foreign president at KAIST, he served as vice-president for two years from 2004. He also served on the Presidential Advisory Council on Science and Technology of the Korean government as vice chairperson from 2015 to 2016.
A renowned scholar in the field of nanoscience, President Shin’s research focuses on the artificial synthesis and characterization of nonmagnetic materials, magnetic anisotropy, and magneto-optical phenomena. He leads the Laboratory for Nanospinics of Spintronic Materials at KAIST and has published in 290 journals while holding 37 patents.
A fellow in the American Physical Society (APS) since 2008, he was the president of the Korean Physical Society from 2011 to 2012. He has been on the editorial board of J. Magnetism and Magnetic Materials from 2009 and was the first Korean recipient of the Asian Union of Magnetics Societies (AUMS) Award, which recognizes outstanding scientists in the field of magnetics.
President Shin envisions making KAIST’s research and education more competitive through continuing innovation. His innovation efforts will extend to the five key areas of education, research, technology commercialization, globalization, and future planning.
Among his priorities, he emphasizes multidisciplinary studies and leadership training for students. He plans to focus on undeclared major courses for undergraduates to help them expand their experience and exposure to diverse disciplines. This approach will help create well-rounded engineers, scientists, and entrepreneurs by enabling them to develop skills while leveraging a strong connection to the arts, humanities, and social sciences.
To better respond to Industry 4.0, which calls for convergence studies and collaborative work, he proposed establishing a ‘Convergence Innovation System’ by strategically selecting 10 flagship convergence research groups. In order to accelerate the technology commercialization and ecosystem of start-ups, he will strengthen entrepreneurship education, making it a prerequisite requirement for students. President Shin said he will spare no effort to incubate and spin-off ventures in which KAIST technology is being transferred. For globalization efforts, he plans to increase the ratio of foreign faculty from 9 percent to 15 percent, while doubling the current foreign student enrollment ratio of 5 percent. For future strategic innovation, he will implement a long-term innovation strategic plan dubbed ‘Vision 2031.’
2017.02.22 View 11501 -
Controlling Turtle Motion with Human Thought
KAIST researchers have developed a technology that can remotely control an animal’s movement with human thought.
In the 2009 blockbuster “Avatar,” a human remotely controls the body of an alien. It does so by injecting human intelligence into a remotely located, biological body. Although still in the realm of science fiction, researchers are nevertheless developing so-called ‘brain-computer interfaces’ (BCIs) following recent advances in electronics and computing. These technologies can ‘read’ and use human thought to control machines, for example, humanoid robots.
New research has demonstrated the possibility of combining a BCI with a device that transmits information from a computer to a brain, or known as a ‘computer-to-brain interface’ (CBI). The combination of these devices could be used to establish a functional link between the brains of different species. Now, researchers from the Korea Advanced Institute of Science and Technology (KAIST) have developed a human-turtle interaction system in which a signal originating from a human brain can affect where a turtle moves.
Unlike previous research that has tried to control animal movement by applying invasive methods, most notably in insects, Professors Phill-Seung Lee of the Mechanical Engineering Department and Sungho Jo of the Computing School propose a conceptual system that can guide an animal’s moving path by controlling its instinctive escape behavior. They chose a turtle because of its cognitive abilities as well as its ability to distinguish different wavelengths of light. Specifically, turtles can recognize a white light source as an open space and so move toward it. They also show specific avoidance behavior to things that might obstruct their view. Turtles also move toward and away from obstacles in their environment in a predictable manner. It was this instinctive, predictable behavior that the researchers induced using the BCI.
The entire human-turtle setup is as follows: A head-mounted display (HMD) is combined with a BCI to immerse the human user in the turtle’s environment. The human operator wears the BCI-HMD system, while the turtle has a 'cyborg system'—consisting of a camera, Wi-Fi transceiver, computer control module, and battery—all mounted on the turtle’s upper shell. Also included on the turtle’s shell is a black semi-cylinder with a slit, which forms the ‘stimulation device.’ This can be turned ±36 degrees via the BCI.
The entire process works like this: the human operator receives images from the camera mounted on the turtle. These real-time video images allow the human operator to decide where the turtle should move. The human provides thought commands that are recognized by the wearable BCI system as electroencephalography (EEG) signals. The BCI can distinguish between three mental states: left, right, and idle. The left and right commands activate the turtle’s stimulation device via Wi-Fi, turning it so that it obstructs the turtle’s view. This invokes its natural instinct to move toward light and change its direction. Finally, the human acquires updated visual feedback from the camera mounted on the shell and in this way continues to remotely navigate the turtle’s trajectory.
The research demonstrates that the animal guiding scheme via BCI can be used in a variety of environments with turtles moving indoors and outdoors on many different surfaces, like gravel and grass, and tackling a range of obstacles, such as shallow water and trees. This technology could be developed to integrate positioning systems and improved augmented and virtual reality techniques, enabling various applications, including devices for military reconnaissance and surveillance.
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Reference: “Remote Navigation of Turtle by Controlling Instinct Behavior via Human Brain-computer Interface,” Journal of Bionic Engineering, July 2016 (DOI: 10.1016/S1672-6529(16)60322-0)
Depiction of Cyborg System
A human controller influences the turtle’s escape behavior by sending left and right signals via Wi-Fi to a control system on the back of the turtle.
2017.02.21 View 15172 -
The 2016 Research Highlights
KAIST has selected the ten most outstanding projects of 2016 conducted by its faculty and researchers. This selection embodies the KAIST research portfolios that translate their discoveries into meaningful and measurable impact toward a better world. All of them demonstrate exceptional creativity, which open new research paths for each field in its novelty, innovation, and impact.
The following list has been reviewed by a committee of faculty peers headed by Associate Vice President for Research. Following are the 2016 KAIST research highlights:
□ Commercialization of 3D Holographic Microscopy
By YongKeun Park of the Department of Physics
Professor YongKeun Park and his colleagues develop a powerful technique to measure 3D images of live cells without labeling agents. This technique, called 3D holographic microscopy or holotomography, will open a new avenue for the study of cell biology and its applications in medical diagnosis. This research also led to the founding of a start-up company Tomocube Inc. and the successful commercialization of the technique.
Professor Park and his research team developed a solution based on digital holography technology used to visualize 3D refractive index tomograms of live cells without staining. This allowed the real-time observation of biological cells in 2D, 3D, and 4D without the use of labeling agents. Conventional techniques for 3D cell imaging requires the use of labeling agents such as fluorescence dyes and proteins, which prevent from investigating the physiology of intact untreated cells. In particular, label-free imaging capability becomes more important in several emerging fields such as stem cell research and immunotherapy.
The team employs the concept of 3D digital holography to achieve the optical measurements of 3D refractive index tomograms of live cells and tissues. Also, a digital micromirror device (DMD), which has been used for DLPTM projectors, was utilized to steer a laser beam for 3D measurements.
Tomocube, founded from seed money funded by the EndRun Project of the Institute for Startup KAIST, succeeded in the commercialization of the 3D holographic microscopy and established an international distribution network in more than ten countries. It now has started exporting the product to several countries. The microscopes are being used in several leading research institutes including MIT, German Cancer Center, Pittsburg Medical Center, and Seoul National University Hospital Selected as one of the top ten mechanical technologies of 2016 by the Korean Society of Mechanical Engineers, the team raised four billion KRW investment from industry leaders including Soft Bank Venture Korea, Hanmi Pharmaceutical, and InterVest investment.
(Figure: Images of cells measured by 3D microscopy)
□ Designer Proteins with Chemical Modifications
By Hee-Sung Park and Hee Yoon Lee of the Department of Chemistry
Professor Hee-Sung Park developed a new strategy for installing authentic post-translational modifications (PTM) into recombinant proteins. Most essential biological processes are controlled by PTM, which plays a critical role in metabolic changes. However, abnormal protein modification aroused by environmental or genetic factors induce diverse diseases such as neurodegenerative diseases, cancer, and many other chronic diseases.
Professor Park has conceived a novel chemical biology route to achieve authentic and selective chemical modifications in proteins.He first used the established O-phosphoserine (Sep) orthogonal translational system to create a Sep-containing protein. The Sep residue is then dephosphorylated to dehydroalanine (Dha). Finally, Zn-Cu is conjugated to Dha of alkyl iodides, which enables it to form chemo-selective carbon-carbon bonds.
This approach offers a powerful tool to engineer designer proteins with diverse chemical modifications, providing a novel platform for investigating numerous diseases and drug development including for cancer and Alzheimer's. Furthermore, this research will allow mass production of abnormally modified proteins that could induce diseases, opening up new prospects in disease treatment research. It will help to enable investigation and discovery of new drug inhibitors that directly target abnormally modified proteins.
(Figure: Application of Customized Protein Modification Technology)
□ Lanthanum-Catalyzed Synthesis of Microporous 3D Graphene-Like Carbons in a Zeolite Template
By Ryong Ryoo, of the Department of Chemistry
Professor Ryong Ryoo’s team presented a scaled-up carbon synthesis viable for practical applications such as Li-ion batteries and catalyst supports.
Zeolite-templated carbon has an extremely large surface area and a regular microporous structure. As a result, it was expected to show excellent performance in various applications, such as for electrode materials or catalyst supports. However, until recently difficulties in synthesis have hindered research on application and properties of zeolited-templated carbon compared to other porous carbon materials.
Professor Ryoo’s team demonstrated that lanthanum ions embedded in zeolite pores lowered the temperature for carbonization of ethylene or acetylene. In this contribution, a graphene-like carbon structure was selectively formed inside zeolite template without the non-selective carbon deposition. Single crystal X-ray diffraction data revealed that carbon formed along the micropore surface. After removal of zeolite template, the carbon framework showed high electrical conductivity.
His synthesis method not only allowed selectivity in ethylene carbonization inside zeolite pore but permitted the diffusion of carbon material even when a large amount of zeolites was synthesized at once, allowing mass production of carbon. Thus, this method is expected to accelerate research on the application and properties of zeolite-templated carbon.
(Figure: Electron density distribution of zeolite that underwent selective pore carbonization. The structure of carbon determined by electron density distributions of carbon atoms, shown in yellow and red, within the framework of zeolite, shown in blue, can be observed.)
□ Complete Prevention of Blood Loss by Self-Sealing Hemostatic Needles
By Haeshin Lee of the Department of Chemistry
Professor Haeshin Lee’s team invented a hemostatic hypodermic needle, which prevented bleeding of punctured tissue during and after injections.
Bleeding unavoidably accompanies injections when a conventional needle penetrates tissue. Though the scale of bleeding from controlled injections does not cause harm to healthy individuals, uncontrolled bleeding may bring serious complications for those who suffer from hemophilia, coagulopathy, or who have been exposed to infectious diseases.
Professor Lee’s hemostatic hypodermic needle is coated with partially cross-linked catechol-functionalized chitosan that undergoes a solid-to-gel phase transition in situ to seal-seal punctured tissues. The team reported a complete prevention of blood loss following intravenous and intramuscular injections in animal models. They observed a 100% survival rate in hemophiliac mice following a syringe injection into a jugular vein.
The self-sealing hemostatic needles may help to prevent complications associated with bleeding in clinical settings such as for diabetic patients who experience delayed hemostasis and in the procedure of biopsy thereby preventing profuse bleeding.
□ An Immunological Mechanism for the Contribution of Commensal Microbiota Against Herpes Simplex Virus Infection in Genital Mucosa
By Heung Kyu Lee of the Graduate School of Medical Science and Engineering
Professor Heung Kyu Lee identified an immunological mechanism of commensal microbiota against herpes virus infections. The protective mechanisms of commensal bacteria against viral infections was limited to how immune inductive signals are provided by commensal bacteria for enhancing innate and adaptive immunity. Until Professor Lee’s research discovery, whether, or how, commensal bacteria might influence the effector arm of immune responses such as effector T cells to eliminate infected virus remained unknown.
Professor Lee’s team demonstrated that dysbiosis within the vaginal microbiota resulted in severe impairment of antiviral protection against HSV-2 infection. IL-33 released into the vaginal tract after antibiotic treatment blocked the ability of effector T cells to migrate into vaginal tissues and secrete the antiviral cytokine, IFN-γ. Thus, the findings suggested a previously unstudied role of commensal bacteria in the effector phase of the antiviral immune response against genital herpes. These findings provided insight into the mechanisms by which the secretion of proteases from opportunistic pathogens in susceptibility to various sexually transmitted pathogens might induce type 2 immunity within the female genital tract.
Promoting awareness of overuse of antibiotics, the research is expected to contribute to the development of viral vaccines with enhanced defense capacity by regulating commensal bacteria to promote health.
□ Development of a Pulse-Echo Laser Ultrasonic Propagation Imaging System
By Jung-Ryul Lee of the Department of Aerospace Engineering
Professor Jung-Ryul Lee’s team for the first time developed a mobile laser ultrasonic propagation imaging system that is capable of 2500-point inspection per second and visualization of pulse-echo ultrasonic wave through the thickness of a solid medium. This novel ultrasonic propagation visualization system has been successfully prototyped for the application of in-situ and in-process nondestructive evaluation of aerospace structures.
The real world proof-of-concept was achieved by testing the new system in the inspection of a space launcher fuselage (KSLV-II), control surfaces of military transport (CN-235), and the brake disk of F-16, guided weapon fuselage. In addition, the system has passed F-16 standard specimen test done by Korea Air Force and got a US patent. The prototype which was developed over a period of two years has been successfully delivered to Korea Air Force last December.
Furthermore, Boeing has expressed interest in prototype development project and KAIST OESL has been selected as the Boeing-KAIST technical contact lab and received a two-year grant from Boeing. The second prototype is under construction for Boeing and the third prototype will be delivered to an optional research institute and used as a standard inspection instrument.
□ Birefractive Stereo Imaging for Single-Shot Depth Acquisition
By Min H. Kim of the School of Computing
Professor Min H. Kim’s team proposed a novel 3D imaging method that allows the capture of not only color pictures but also corresponding depth images while traditional cameras capture just color pictures.
Depending on the polarization state of light, the incident light on a birefringent material such as calcite can be refracted into two different angles. This physical phenomenon is called double refraction. Whereas traditional stereo imaging requires at least two stereo cameras, 3D imaging method can capture depth from a single picture of double refraction. This proposed 3D imaging technique can be applied to many graphics and computer vision applications such as AR/VR applications that require color and depth information simultaneously.
This technology, which could measure depth images, is currently needed for various industrial applications. The suggested method in this research to measure depth information from one photo using double refraction media accurately can be used in areas where system size and cost are important, such as mobile cameras, VR/ARs, driverless cars, and 3D microscopes.
(Figure: Measuring high-resolution depth of single image via bi-refringent medium)
□Development of Environment Friendly Geotechnical Construction Material Using Biopolymer
By Gye-Chun Cho of the Department of Civil and Environmental Engineering
Professor Gye-Chun Cho has succeeded in making a 100% bio-based KABS (KAIST Bio-Soil) binder using biopolymer, an eco-friendly geotechnical construction material. A biopolymer is an organic polymer produced in the course of microbial activities and thus is an eco-friendly material manufactured without generating carbon dioxide. Biopolymers have been used in food, agriculture, cosmetics, and medicine as hardener and gelling agents, but have never been applied in construction. His team verified the microscopic interaction, feasibility, and strengthening mechanism of microbial biopolymers for soils for the first time in the world, suggesting that biopolymers be an eco-friendly soil binder.
In addition to soil binders, biopolymers can also be applied to various fields of ground construction (e.g., ground improvement, grouting, erosion control, vegetation, anti-desertification, etc.). The team expects more biopolymer applications in construction since increasing demands for replacing cement-based or chemical ground materials have surged.
With KABS binder, the team has performed several field tests along with industrial technology transfer underway. In collaboration with the Korea Expressway Corporation and LH Corporation, Professor Cho’s team is working on additional commercial applications.
(Figure: Strength enhancement effect of soil grain processed by biopolymer )
□ Protein Delivery Via Engineered Exosomes
By Chulhee Choi of the Department of Bio and Brain Engineering
Professor Chulhee Choi’s team unveiled a new tool for intracellular delivery of target proteins, named “exosomes for protein loading via optically reversible protein-protein interactions” or “EXPLORs”.
Nanoparticle-mediated delivery of functional macromolecules is a promising method for treating a variety of human diseases. Among nanoparticles, cell-derived exosomes have recently gained attention as a new therapeutic strategy for the in vivo delivery of nucleotides and chemical drugs.
By integrating a reversible protein-protein interaction module controlled by blue light with the endogenous process of exosome biogenesis, the team successfully loaded cargo proteins into newly generated exosomes. Treatment with protein-loaded EXPLORs is shown to significantly increase intracellular levels of cargo proteins and their function in recipient cells in vitro and in vivo.
These results clearly indicate the potential of EXPLORs as a mechanism for the efficient intracellular transfer of protein-based therapeutics into recipient cells and tissues. This technology has been transferred to KAIST bio-venture Cellex Life Science, Incorporated for commercialization.
□ Hot Electron Detection under Catalytic Reactions
By Jeong Young Park of the Graduate School of EEWS
Professor Jeong Young Park’s team developed a novel catalytic nanodiode consisting of a thin metal catalyst deposited onto a semiconductor support. The team succeeded in observing in real-time hot electrons created in the course of catalytic reaction occurring at atmospheric pressure or at liquid-solid interfaces.
Use of a noble catalytic nanodiode is a new measurement system that detects hot electrons produced on catalyst surface through atmospheric pressure and liquid chemical reaction in real time that allows direct identification of the catalytic activity of catalytic reactions. In particular, the system allows macro-observation of hot-electron movements that change with the type of nano-catalyst without high-priced equipment in atmospheric pressure and liquidation, and thus is not limited to experimental conditions such as in ultrahigh vacuums.
Therefore, it could be applied in the future to analyze complex chemical reaction mechanisms of catalysts used in high temperature and various pressure conditions, and to develop high efficiency next-generation catalyst materials. This finding may lead not only to the fundamental understanding in the mechanism of the catalytic reactions but also to the development of next-generation catalysts with enhanced catalytic performance.
(Figure: Schematic diagrams of nano-catalyst hot electron element and graphene hot electron detector)
2017.02.20 View 13727 -
Professor Shin Honored Posthumously for Iridescent Microparticles
(The Late Professor Joong-Hoon Shin (left) and Professor Shin-Hyun Kim)
A research team co-led by Professor Shin-Hyun Kim from the Department of Chemical and Biomolecular Engineering and Professor Jong-Ryul Jeong from the Department of Materials Science and Engineering at Chungnam National University developed iridescent microparticles with a structural color gradient. The research team posthumously dedicated their research to a renowned professor in the field of nanophotonics, the late Professor Joong-Hoon Shin of the Graduate School of Nanoscience and Technology at KAIST. He passed away suddenly in a car accident last September.
The iridescent microparticles, which allow on-demand control over structural color, will be key components for next-generation reflection-mode displays with clear color realization even in direct sunlight.
Materials such as opals, Morpho butterfly wings, and peacock feathers all display beautiful colors without pigment, using regularly-spaced nanostructures. Regularly-spaced nanostructures render color, by selectively reflecting the light of a particular wave through light interference. As such, materials that possess periodic modulation of refractive index at subwavelength scale are referred to as photonic crystals.
In general, photonic crystals are only able to display a single color, so limitations exist when attempting to apply them to reflection-mode displays which call for multiple structural colors. The research team addressed the issue using inspiration from snowflakes stacking in the winter. When snow falls on the surface of a round-shaped structure, the thickness of the snow stacking differs depending on the orientation. Based on this observation, the research team created photonic microparticles with a structural color gradient by depositing two different materials on spherical microparticles.
When some material is deposited on the surface of a sphere, the material on the top is thickest and becomes thinner on the sides. The team alternately deposited titania and silica on the spherical microparticles to form periodic modulation of the refractive index. The thickness of the alternating photonic layers is reduced along the angle from the top, which yields a structural color gradient.
Consequently, the microparticles reflect long-wavelength red light from the top of the sphere and short-wavelength blue light from the side of the sphere. Any color of the visible spectrum can be selected in between the top and side depending on the orientation of the microparticles.
The research team used an external magnetic field as a way to control the orientation of the photonic microparticles and the structural colors. As magnetic iron layer was deposited underneath the alternating photonic layer, it was possible to freely control the orientation of the microparticles using a magnet, thereby allowing control of the color seen by the users.
KAIST doctoral candidate Seung Yeol Lee of the Department of Chemical and Biomolecular Engineering is the first author of this research, with support from the Midcareer Researcher Program of the National Research Foundation and funded by the Ministry of Science, ICT, and Future Planning (MSIP). This research was published in the online edition of Advanced Materials on February 6, 2017.
Figure1: Sets of an OM image of photonic Janus microspheres and an SEM image showing a cross-section of the photonic layers.
Figure 2: A series of schematics and OM images showing the color change depending on the orientation angle of the photonic Janus microsphere.
2017.02.17 View 8876 -
A New Approach to 3D Holographic Displays Greatly Improves the Image Quality
With the addition of holographic diffusers or frosted glasses to wavefront modulators, KAIST researchers offer a simple and practical solution to significantly enhance the performance of 3D dynamic holographic displays by 2,600 times.
The potential applications of three-dimensional (3D) digital holograms are enormous. In addition to arts and entertainment, various fields including biomedical imaging, scientific visualization, engineering design, and displays could benefit from this technology. For example, creating full-sized organs for 3D analysis by doctors could be helpful, but it remained a challenge owing to the limitation of hologram-generation techniques.
A research team led by Professor YongKeun Park of the Physics Department at KAIST has come up with a solution and developed a 3D holographic display that performs more than 2,600 times better than existing 3D holographic displays. This study is expected to improve the limited size and viewing angle of 3D images, which were a major problem of the current holographic displays. The study was published online in Nature Photonics on January 23, 2017.
3D holograms, which often appear in science fiction films, are a familiar technology to the public, but holograms in movies are created with computer graphic effects. Methods for creating true 3D holograms are still being studied in the laboratory. For example, due to the difficulty of generating real 3D images, recent virtual reality (VR) and augmented reality (AR) devices project two different two-dimensional (2D) images onto a viewer to induce optical illusions.
To create a 3D hologram that can be viewed without special equipment such as 3D glasses, the wavefront of light must be controlled using wavefront modulators such as spatial light modulators (SLMs) and deformable mirrors (DMs). A wavefront modulator is an optical manipulation device that can control the direction of light propagation.
However, the biggest limitation to using these modulators as 3D displays is the number of pixels. The large number of pixels that are packed into high-resolution displays developed in recent years are suitable for a 2D image, and the amount of information contained in those pixels cannot produce a 3D image. For this reason, a 3D image that can be made with existing wavefront modulator technology is 1 cm in size with a narrow viewing angle of 3 degrees, which is far from practicable.
As an alternative, KAIST researchers used a DM and added two successive holographic diffusers to scatter light. By scattering light in many directions, this allows for a wider viewing angle and larger image, but results in volume speckle fields, which are caused by the interference of multiple scattered light. Random volume speckle fields cannot be used to display 3D images.
To fix the problem, the researchers employed a wavefront-shaping technique to control the fields. As a result, they succeeded in producing an enhanced 3D holographic image with a viewing angle of 35 degrees in a volume of 2 cm in length, width, and height. This yielded a performance that was about 2,600 times stronger than the original image definition generated when they used a DM without a diffuser.
Professor Park said, “Scattering light has previously been believed to interfere with the recognition of objects, but we have demonstrated that current 3D displays can be improved significantly with an increased viewing angle and image size by properly controlling the scattered light.”
Hyeonseung Yu, who is the lead author of this research article and a doctoral candidate in the Department of Physics, KAIST, noted that this technology signals a good start to develop a practical model for dynamic 3D hologram displays that can be enjoyed without the need for special eyeglasses. “This approach can also be applied to AR and VR technology to enhance the image resolution and viewing angles,” added Yu.
The research paper is entitled “Ultrahigh-definition Dynamic 3D Holographic Display by Active Control of Volume Speckle Fields.”
Figure 1. Concept of Scattering Display
The size and viewing angle of 3D images can be simultaneously increased when a scattering medium (diffuser) is introduced. By controlling the wavefront impinging on the scattering medium, the desired 3D hologram is generated.
Figure 2. Experimental Setup
The optical set-up consists of a deformable mirror and the scattering medium with two successive holographic diffusers. A high-numerical-aperture imaging unit mounted on a three-axis motorized translational system is utilized for wavefront optimization and imaging.
Figure 3. 3D Images Projected
This picture shows 3D images in a volume of 2 cm × 2 cm × 2 cm with a viewing angle of 35 degrees using one of the wavefront modulators, a digital micromirror device (DMD).
Figure 4. Artist’s Rendition of the Proposed Concept
A dynamic 3D hologram of a face is displayed.
2017.02.01 View 13755 -
Humanoid Robot Research Center Opened
(Photo from left: Kyong-Hoon Kim from Korea Evaluation Institute of Industrial Technology, Vice President of Research at KAIST Hee-Yoon Lee, Director Oh, Jong-Hwan Kim at the Ministry of Trade, Industry and Energy, President Ki-Han Park at the Korea Institute for Robot Industry Advancement, and Dean of KAIST Institute Yun Chol Chung.)
KAIST opened its Humanoid Robot Research Center on January 19 at the KAIST Institute. Endorsed by the Ministry of Trade, Industry and Energy with 15 billion KRW funding over five years, the center will conduct research for advancing humanoid robot technology and fostering research fellows in the field.
Professor Jun Ho Oh at the Department of Mechanical Engineering will serve as the director of the center. Team KAIST under Professor Oh won the 2015 DARPA Robotics Challenge (DRC) with its humanoid robot DRC-HUBO, beating 23 teams from six countries.
Professor Oh said, “I believe we have already achieved technological prowess through developing the HUBO robot over the past decade. The center will continue to strive for further development of original technology crucial for humanoid robots’ key components. We want to pave the way for having enough of our own technology and needing to bring in technology from abroad. Professor Oh said he will focus on fields such as high-efficiency, high-powered electric drives and hydraulic system humanoid robot capable of executing solid manipulability with high confidence and object recognition intelligence technology. In addition, he said the center will develop module type and extended open software in an effort to disseminate robot technology.
2017.01.23 View 7532 -
Adsorbent That Can Selectively Remove Water Contaminants
Professor Cafer T. Yavuz and his team at the Graduate School of Energy, Environment, Water, and Sustainability (EEWS) have developed an adsorbent that can selectively capture soluble organic contaminants in water.
This water treatment adsorbent is a fluorine-based nanoporous polymer that can selectively remove water-soluble micromolecules. It has the added advantage of being cheap and easily synthesized, while also being renewable.
The results of this research have been published online in Nature Communication on November 10, 2016. The research paper is titled “Charge-specific Size-dependent Separation of Water-soluble Organic Molecules by Fluorinated Nanoporous Networks.” (DOI: 10.1038/ncomms13377)
Water pollution is accelerating as a result of global industrial development and warming. As new materials are produced and applied in the agricultural and industrial sectors, the types of contaminants expelled as sewage and waste water are also becoming diverse.
Chemicals such as dyes and pesticides can be especially harmful because they are made up of small and highly soluble organic particles that cannot be completely removed during the water treatment process, ultimately ending up in our drinking water.
The current conventional water treatment systems utilize processes such as activated carbon, ozonolysis, and reverse osmosis membrane. These processes, however, are designed to remove larger organic molecules with lower solubility, thus removal of very small molecules with high solubility is difficult. In addition, these micromolecules tend to be charged, therefore are less easily separated in aqueous form.
The research team aimed to remove these small molecules using a new adsorbent technology.
In order to remove aqueous organic molecular contaminants, the team needed an adsorbent that can adsorb micro-sized molecules. It also needed to introduce a chemical function that would allow it to selectively adsorb molecules, and lastly, the adsorbent needed to be structurally stable as it would be used underwater.
The team subsequently developed an adsorbent of fluorine-based porous organic polymer that met all the conditions listed above. By controlling the size of the pores, this adsorbent is able to selectively adsorb aqueous micromolecules of less than 1-2 nm in size.
In addition, in order to separate specific contaminants, there should be a chemical functionality, such as the ability to strongly interact with the target material. Fluorine, the most electronegative atom, interacts strongly with charged soluble organic molecules.
The research team incorporated fluorine into an adsorbent, enabling it to separate charged organic molecules up to 8 times faster than neutral molecules.
The adsorbent developed by Professor Yavuz’s team has wide industrial applications. It can be used in batch-adsorption tests, as well as in column separation for size- and charge-specific adsorption.
Professor Yavuz stated that “the charge-selective properties displayed by fluorine has the potential to be applied in desalination or water treatment processes using membranes."
This paper was first-authored by Dr. Jeehye Byun, and the research was funded by KAIST’s High Risk High Return Program and the Ministry of Science, ICT and Future Planning of Korea’s Mid-Career Researcher Program, as well as its Technology Development Program to Solve Climate Change.
Figure 1. Diagram conceptualizing the process of charge- and size-specific separation by the fluorine-based porous polymer adsorbent
Figure 2. Difference in absorbance before and after using a porous fluorine polymer column to separate organic molecules
Figure 3. Adsorption properties of a fluorine polymer according to the charge and size of organic molecules
2017.01.17 View 10415