Science
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An Improved Carbon Nanotube Semiconductor
Professor Yang-Kyu Choi and his research team of the School of Electrical Engineering at KAIST collaborated with Professor Sung-Jin Choi of Kookmin University to develop a large-scale carbon nanotube semiconductor by using a 3-D fin-gate structure with carbon nanotubes on its top.
Dong Il Lee, a postdoctoral researcher at KAIST’s Electrical Engineering School, participated in this study as the first author. It was published in ACS Nano on November 10, 2016, and was entitled “Three-Dimensional Fin-Structured Semiconducting Carbon Nanotube Network Transistor.”
A semiconductor made with carbon nanotubes operates faster than a silicon semiconductor and requires less energy, yielding higher performance.
Most electronic equipment and devices, however, use silicon semiconductors because it is difficult to fabricate highly purified and densely packed semiconductors with carbon nanotubes (CNTs).
To date, the performance of CNTs was limited due to their low density. Their purity was also low, so it was impossible to make products that had a constant yield on a large-surface wafer or substrate. These characteristics made the mass production of semiconducting CNTs difficult.
To solve these difficulties, the research team used a 3-D fin-gate to vapor-deposit carbon nanotubes on its top. They developed a semiconductor that had a high current density with a width less than 50 nm.
The three-dimensional fin structure was able to vapor-deposit 600 carbon nanotubes per micrometer. This structure could have 20 times more nanotubes than the two dimensional structure, which could only vapor-deposit thirty in the same 1 micrometer width.
In addition, the research team used semi-conductive carbon nanotubes having a purity rating higher than 99.9% from a previous study to obtain a high yield semiconductor.
The semiconductor from the research group has a high current density even with a width less than 50 μm. The new semiconductor is expected to be five times faster than a silicon-based semiconductor and will require five times less electricity during operation.
Furthermore, the new semiconductor can be made by or will be compatible with the equipment for producing silicon-based semiconductors, so there will be no additional costs.
Researcher Lee said, “As a next generation semiconductor, the carbon nanotube semiconductor will have better performance, and its effectiveness will be higher.” He also added, “Hopefully, the new semiconductor will replace the silicon-based semiconductors in ten years.”
This study received support from the Center for Integrated Smart Sensors funded by the Ministry of Science, ICT & Future Planning of Korea as the Global Frontier Project, and from the CMOS (Complementary Metal-Oxide-Semiconductor) THz Technology Convergence Center of the Pioneer Research Center Program sponsored by the National Research Foundation of Korea.
Picture 1: 3D Diagram of the Carbon Nanotube Electronic Device and Its Scanning Electron Microscope (SEM) Image
Picture 2: 3D Transistor Device on an 8-inch Base and the SEM Image of Its Cross Section
2017.02.16 View 11518 -
New Building Endowed in Bio and Brain Engineering Department
An endowment from the former Chairman of Mirae Industries, Moon Soul Chung, was used to establish the Yang Bun Soon Building in the Bio and Brain Engineering Department at KAIST. The opening ceremony for the building took place on February 8 and was attended by President Sung-Mo Kang, KAIST administrators, faculty, and students.
The Yang Bun Soon Building, named after the wife of Chairman Chung, is a new addition to the Bio and Brain Engineering Department complex. The five-story building was erected next to the 11-story Chung Moon Soul Building, which was completed in 2003 using a portion of his first endowment to KAIST. Chairman Chung donated approximately 30 billion KRW for funding a convergence research for IT and BT in 2001.
The new building was completed with financing from Chung’s second endowment of 21.5 billion KRW in support of the fields of brain and cognitive sciences in 2014. The building will accommodate both lab facilities and lecture halls.
At the ceremony, President Kang thanked the Chungs for their continuing generosity to KAIST. He commended Chung for showing how entrepreneurs can fulfill their social responsibility by supporting Korea’s future through donations and support.
(Photo caption: Chung Moon Soul Building (left) and Yang Bun Soon Building(right))
2017.02.09 View 6345 -
Dr.M Drives Smart Healthcare Industry in Partnership with Hancom
President Sung-Mo Kang signed an agreement on January 25 with Hancom Group Chairman Sang Chul Kim to establish a smart healthcare complex in Gapyeong, Kyonggido. With the Gapyeong complex launch, KAIST will come to commercialize Dr. M system along with other Dr.M consortium members as a new growth engine to drive the smart health industry.
Dr. M is a smart healthcare platform developed by the Health Science Research Institute at KAIST in 2014. Dr. M is capable of analyzing and predicting diseases, as well as prescribing, by incorporating ICT and medical technologies. Dr. M applies diverse technologies such as healthcare sensors, wearable devices, low-power communications technology, and cloud and big data collection platforms.
Hancom Group, a leading computer software company in Korea, has participated in the project since 2015 for advancing the smart healthcare market by developing mobile healthcare software program. Hancom joined the Dr.M consortium launched last November.
(President Kang (left) poses with Hancom Chairman Kim after signing.)
2017.02.03 View 7147 -
JETS Conference 2017
KAIST and four science and technology research universities in Korea co-hosted a technology start-up fair, the 2017 JETS (Job, Exhibition, Tech Forum, and Startup) Conference January 19 ~20 in the Ryu Geun-chul Sports Complex at KAIST.
Korea’s major science and technology research universities, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Gwangju Institute of Science and Technology (GIST), Pohang University of Science and Technology (Postech), and Ulsan National Institute of Science and Technology (UNIST), held the event in a collaborative effort to educate, inspire, and connect young entrepreneurs, especially those who will launch technology start-ups.
The conference brought entrepreneurs and innovators together who seek ways of working with and supporting start-ups and for their sustainable growth. It also drew aspiring young students and researchers from universities and the government-funded research institutions who are in the process of commercializing their technology. Students from each university’s industry-academia cooperation program who incubated their technology and ideas were key contributors.
At the Tech Forum, entrepreneurship and technology consultation specialists including Joe Jasin, managing director at DNA Investment Partners in the US, the founder of Cyworld Dong-Hyung Lee, and Professor Hawoong Jeong, a complex bio-network specialist from the Department of Physics of KAIST lectured on the ecosystem of start-ups and its trends and development.
The Dean of University-Industry Cooperation at KAIST Joongmyeon Bae said, "We organized this event in collaboration with four major research universities to further encourage technology start-ups from young students and help their ideas and technology bear fruit. We will continue to strive to create an ecosystem of start-ups which works efficiently.”
(Above photo: Founder of the Cyworld, Dong-Hyung Lee gives a lecture at the Tech Forum. Below photo: Students visit exhibition booth of each participating institution.)
2017.01.20 View 12806 -
KAIST Ph.D. Candidate Wins the Next Generation of Engineers Award
Joo-Sung Kim, a doctoral student at the EEWS (Environment, Energy, Water and Sustainability) Graduate School won the inaugural Next Generation of Engineers Award in Leadership on December 14, 2016.
The National Academy of Engineering of Korea hosts this award to support creative and ambitious students who have the potential to become leaders in engineering and who will serve as role models for future Korean engineers. Based on the recommendations of university professors in engineering and members of the academy, seven students are selected for the award in the categories of leadership and entrepreneurship.
With his research focus on the development of high-performance, next-generation secondary cells for wearable devices such as smart watches, health bands, and smart eyewear, Joo-Sung created a startup, Lithium-ion Battery Energy Science and Technology (LiBEST), Inc. He plans to base his company at the Office of University and Industry Cooperation, KAIST, where he can receive assistance for launching the mass-production system for his technology.
His adviser, Professor Jang-Wook Choi of the EEWS Graduate School, noted, “Joo-Sung has been a great student who has a strong sense of curiosity and perseverance. The award is the by-product of his hard work.”
“I have always enjoyed my work and study as a researcher, but eventually would like to expand my career into business based on the results of my research. It would be wonderful if I could become a businessman like Elon Musk, Masayoshi Son, or Ma Yun and create a role model for aspiring engineers in Korea by combining science and technology with business demand to create social values that benefit many people,” Joo-Young said.
2016.12.26 View 11274 -
EEWS Graduate School Team Receives the S-Oil Best Paper Award
Professor Hyungjun Kim and Dr. He-Young Shin from the EEWS (Energy, Environment, Water and Sustainability) Graduate School at KAIST received the Best Paper Award in Chemistry from S-Oil, a Korean petroleum and refinery company, on November 29, 2016.
Established in 2011, the S-Oil Best Paper Awards are bestowed annually upon ten young scientists in the fields of five basic sciences: mathematics, physics, chemistry, biology, and earth science. The scientists are selected at the recommendation of the Korean Academy of Science and Technology and the Association of Korean Universities. The awards grant a total of USD 230,000 for research funding.
Dr. Shin, the lead author of the awarded research paper, said, “My research interest has been catalyst studies based on theoretical chemistry. I am pleased to accept this award that will support my studies, and will continue to research catalyst design that can predict parameters and integrate them into catalytic systems.”
Professor Hyungjun Kim (left) and Dr. He-Young Shin (right)
2016.12.23 View 10997 -
Professor Dongman Lee Wins the 2016 Korea Internet Award
Professor Dongman Lee of KAIST’s School of Computing received the 11th Korea Internet Award in the category of personal achievement on December 13 at the Creative Economy and Innovation Center in Gyeonggi province.
Hosted by the Ministry of Science, ICT and Future Planning of Korea, the Internet Award recognizes leaders in the Internet industry and their contributions.
Since 2010, Professor Lee has conducted research on the Internet of Things (IoT) platforms, resulting in the publication of five research papers in Science Citation Index (SCI) journals, ten papers in Korean journals, 30 best papers nominations at international conferences, and the registration of eleven patents. He has also worked on the creation of an IoT ecosystem through his research on object interworking platforms that can provide diverse user-customized services in the IoT environment.
His research team built a test bed for applicable IoT platforms on the 8th floor of the IT Convergence Center on campus to implement experiments and collect various data, thereby creating a foundation to carry out research projects in this field.
Professor Lee has helped the advancement of an Internet governance system in Korea by researching Internet governance policies, holding important posts in related academic societies including the Chairman of the Korea Internet Governance Alliance (KIGA) Council, and hosting major conferences such as the Asia Pacific Regional Internet Governance Forum (APrIGF).
2016.12.20 View 9025 -
KAIST's Doctoral Student Receives a Hoffman Scholarship Award
Hyo-Sun Lee, a doctoral student at the Graduate School of EEWS (Environment, Energy, Water and Sustainability), KAIST, is a recipient of the 2016 Dorothy M. and Earl S. Hoffman Scholarships presented by the American Vacuum Society (AVS). The award ceremony took place during the Society’s 63rd International Symposium and Exhibition on November 6-11, 2016 in Nashville, Tennessee.
Lee is the first Korean and foreign student to receive this scholarship.
The Hoffman Scholarships were established in 2002 to recognize and encourage excellence in graduate studies in the sciences and technologies of interest to AVS. The scholarships are funded by a bequest from Dorothy M. Hoffman, who was a pioneering member of the Society of Women Engineers and served as the president of AVS in 1974.
Lee received the scholarship for her research that detects hot electrons from chemical reactions on catalytic surface using nanodevices. Nano Letters, an academic journal published by the American Chemical Society, described her work in its February 2016 issue as a technology that allows quantitative analysis of hot electrons by employing a new nanodevice and therefore helps researchers understand better the mechanism of chemical reactions on nanocatalytic surface. She also published her work to detect the flow of hot electrons that occur on metal nanocatalytic surface during hydrogen oxidation reactions in Angewandte Chemie.
Lee said, “I am pleased to receive this honor from such a world-renowned academic society. Certainly, this will be a great support for my future study and research.”
Founded in 1953, AVS is an interdisciplinary, professional society composed of approximately 4,500 members worldwide. It supports networking among academic, industrial, government, and consulting professionals involved in a range of established and emerging science and technology areas such as chemistry, physics, engineering, business, and technology development.
2016.11.17 View 10386 -
Key Interaction between the Circadian Clock and Cancer Identified
Professor Jae Kyoung Kim and his research team from the Department of Mathematical Sciences at KAIST found that the circadian clock drives changes in circadian rhythms of p53 which functions as a tumor suppressor. Using a differential equation, he applied a model-driven mathematical approach to learn the mechanism and role of p53.
Kim’s mathematical modeling has been validated by experimental studies conducted by a research team at Virginia Polytechnic Institute and State University (Virginia Tech) in the United State, which is led by Professor Carla Finkielstein. As a result, the researchers revealed that there is an important link existed between the circadian clock and cancer.
The findings of this research were published online in Proceedings of the National Academy of Sciences of the United States of the America (PNAS) on November 9, 2016.
The circadian clock in our brain controls behavioral and physiological processes within a period of 24 hours, including making us fall asleep at a certain time by triggering the release of the sleep hormone melatonin in our brain, for example, around 9 pm. The clock is also involved in various physiological processes such as cell division, movement, and development.
Disruptions caused by the mismatch of the circadian clock and real time due to chronic late night work, shiftwork, and other similar issues may lead to various diseases such as diabetes, cancer, and heart disease.
In 2014, when Kim met with Finkielstein, her research team succeeded in observing the changes of p53 over a period of 24 hours, but could not understand how the circadian clock controls the 24-hour rhythm of p53. It was difficult to determine p53’s mechanism since its cell regulation system is far more complex than other cells
To solve the problem, Kim set up a computer simulation using mathematical modeling and ran millions of simulations. Instead of the traditional method based on trial and error experiments, mathematical modeling allowed to save a great deal of time, cost, and manpower.
During this process, Kim proved that the biorhythm of p53 and Period2, an important protein in the circadian clock, are closely related. Cells usually consist of a cell nucleus and cytoplasm. While p53 exists in both nucleus and cytoplasm, it becomes more stable and its degradation slows down when it is in the nucleus.
Kim predicted that the Period2 protein, which plays a key role in the functioning of the circadian clock, could influence the nucleus entry of the p53 protein.
Kim’s predictions based on mathematical modeling have been validated by the Virginia team, thereby revealing a strong connection between the circadian clock and cancer.
Researchers said that this research will help explain the cause of different results from numerous anticancer drugs, which are used to normalize the level of p53, when they are administrated at different times and find the most effective dosing times for the drugs.
They also believe that this study will play an important role in identifying the cause of increasing cancer rates in shift-workers whose circadian clocks are unstable and will contribute to the development of more effective treatments for cancer.
Professor Kim said, “This is an exciting thing that my research can contribute to improving the healthy lives of nurses, police officers, firefighters, and the like, who work in shifts against their circadian rhythms. Taking these findings as an opportunity, I hope to see more active interchanges of ideas between biological sciences and mathematical science in Korea.”
This research has been jointly conducted between KAIST and Virginia Tech and supported by the T. J. Park Science Fellowship of POSCO, the National Science Foundation of the United States, and the Young Researcher Program of the National Research Foundation of Korea.
Picture 1. The complex interaction between tumor antigen p53 and Period2 (Per2) which plays a major role in the circadian clock as revealed by mathematical simulations and experiments
Picture 2. A portion of the mathematical model used in the research
Picture 3. Professor Jae Kyoung Kim (third from left) and the Virginia Tech Research Team
2016.11.17 View 8054 -
2016 KAIST EEWS Workshop
The Energy, Environment, Water and Sustainability (EEWS) Graduate School of KAIST hosted a workshop entitled “Progress and Perspectives of Energy Science and Technology” on October 20, 2016. The workshop took place at the Fusion Hall of the KAIST Institute on campus.
About 400 experts in energy science and engineering participated in the event. Eight globally recognized scientists introduced the latest research trends in nanomaterials, energy theory, catalysts, and photocatalysts and led discussions on the current status and prospects of EEWS.
Professors Yi Cui of Stanford University, an expert in nanomaterials, and William A. Goddard of California Institute of Technology presented their research experiments on materials design and recent results on the direction of theory under the topics of energy and environment.
Dr. Miquel Salmeron, a former head of the Material Science Division of Lawrence Berkeley National Laboratory, and Professor Yuichi Ikuhara of Tokyo University introduced their analysis of catalysts and energy matters at an atomic scale.
Professor Sukbok Chang of the Chemistry Department at KAIST, a deputy editor of ACS Catalysis and the head of the Center for Catalytic Hydrocarbon Functionalizations at the Institute of Basic Science, and Professor Yang-Kook Sun of Energy Engineering at Hanyang University, who is also a deputy editor of ACS Energy Letters, presented their latest research results on new catalytic reaction development and energy storage.
The workshop consisted of three sections which addressed the design of energy and environment materials; analysis of energy and catalytic materials; and energy conversion and catalysts.
The EEWS Graduate School was established in 2008 with the sponsorship of the Korean government’s World Class University (WCU) project to support science education in Korea. Professor J. Fraser Stoddart, the winner of the 2016 Nobel Prize in Chemistry, was previously worked at the KAIST EEWS Graduate School as a WCU visiting professor for two years, from 2011 to 2013. Professor Ali Coskun, who was a postdoctoral researcher in the laboratory of Professor Stoddart, now teaches and conducts research as a full-time professor at the graduate school.
Dean Yousung Jung of the EEWS Graduate School said:
“This workshop has provided us with a meaningful opportunity to engage in discussions on energy science and technology with world-class scholars from all around the world. It is also a good venue for our graduate school to share with them what we have been doing in research and education.”
2016.10.20 View 13435 -
Extremely Thin and Highly Flexible Graphene-Based Thermoacoustic Speakers
A joint research team led by Professors Jung-Woo Choi and Byung Jin Cho of the School of Electrical Engineering and Professor Sang Ouk Kim of the Material Science and Engineering Department, all on the faculty of the Korea Advanced Institute of Science and Technology (KAIST), has developed a simpler way to mass-produce ultra-thin graphene thermosacoustic speakers.
Their research results were published online on August 17, 2016 in a journal called Applied Materials & Interfaces. The IEEE Spectrum, a monthly magazine published by the Institute of Electrical and Electronics Engineers, reported on the research on September 9, 2016, in an article titled, “Graphene Enables Flat Speakers for Mobile Audio Systems.” The American Chemical Society also drew attention to the team’s work in its article dated September 7, 2016, “Bringing Graphene Speakers to the Mobile Market.”
Thermoacoustic speakers generate sound waves from temperature fluctuations by rapidly heating and cooling conducting materials. Unlike conventional voice-coil speakers, thermoacoustic speakers do not rely on vibrations to produce sound, and thus do not need bulky acoustic boxes to keep complicated mechanical parts for sound production. They also generate good quality sound in all directions, enabling them to be placed on any surface including curved ones without canceling out sounds generated from opposite sides.
Based on a two-step, template-free fabrication method that involved freeze-drying a solution of graphene oxide flakes and the reduction/doping of oxidized graphene to improve electrical properties, the research team produced a N-doped, three-dimensional (3D), reduced graphene oxide aerogel (N-rGOA) with a porous macroscopic structure that permitted easy modulation for many potential applications.
Using 3D graphene aerogels, the team succeeded in fabricating an array of loudspeakers that were able to withstand over 40 W input power and that showed excellent sound pressure level (SPL), comparable to those of previously reported 2D and 3D graphene loudspeakers.
Choong Sun Kim, the lead author of the research paper and a doctoral student in the School of Electrical Engineering at KAIST, said:
“Thermoacoustic speakers have a higher efficiency when conducting materials have a smaller heat capacity. Nanomaterials such as graphene are an ideal candidate for conductors, but they require a substrate to support their extremely thinness. The substrate’s tendency to lose heat lowers the speakers’ efficiency. Here, we developed 3D graphene aerogels without a substrate by using a simple two-step process. With graphene aerogels, we have fabricated an array of loudspeakers that demonstrated stable performance. This is a practical technology that will enable mass-production of thermosacoustic speakers including on mobile platforms.”
The research paper is entitled “Application of N-Doped Three-Dimensional Reduced Graphene Oxide Aerogel to Thin Film Loudspeaker.” (DOI: 10.1021/acsami.6b03618)
Figure 1: A Thermoacoustic Loudspeaker Consisted of an Array of 16 3D Graphene Aerogels
Figure 2: Two-step Fabrication Process of 3D Reduced Graphene Oxide Aerogel Using Freeze-Drying and Reduction/Doping
Figure 3: X-ray Photoelectron Spectroscopy Graph of the 3D Reduced Graphene Oxide Aerogel and Its Scanning Electron Microscope Image
2016.10.05 View 14496 -
Professor Seyun Kim Identifies a Neuron Signal Controlling Molecule
A research team led by Professor Seyun Kim of the Department of Biological Sciences at KAIST has identified inositol pyrophosphates as the molecule that strongly controls neuron signaling via synaptotagmin.
Professors Tae-Young Yoon of Yonsei University’s Y-IBS and Sung-Hyun Kim of Kyung Hee University’s Department of Biomedical Science also joined the team.
The results were published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on June 30, 2016.
This interdisciplinary research project was conducted by six research teams from four different countries and covered a wide scope of academic fields, from neurobiology to super resolution optic imaging.
Inositol pyrophosphates such as 5-diphosphoinositol pentakisphos-phate (5-IP7), which naturally occur in corns and beans, are essential metabolites in the body. In particular, inositol hexakisphosphate (IP6) has anti-cancer properties and is thought to have an important role in cell signaling.
Inositol pentakisphosphate (IP7) differs from IP6 by having an additional phosphate group, which was first discovered 20 years ago. IP7 has recently been identified as playing a key role in diabetes and obesity.
Psychopathy and neurodegenerative diseases are known to result from the disrupted balance of inositol pyrophosphates. However, the role and the mechanism of action of IP7 in brain neurons and nerve transmission remained unknown.
Professor Kim’s team has worked on inositol pyrophosphates for several years and discovered that very small quantities of IP7 control cell-signaling transduction. Professor Yoon of Yonsei University identified IP7 as a much stronger inhibitor of neuron signaling compared to IP6. In particular, IP7 directly suppresses synaptotagmin, one of the key proteins in neuron signaling. Moreover, Professor Kim of Kyung Hee University observed IP7 inhibition in sea horse neurons.
Together, the joint research team identified inositol pyrophosphates as the key switch metabolite of brain-signaling transduction.
The researchers hope that future research on synaptotagmin and IP7 will reveal the mechanism of neuron-signal transduction and thus enable the treatment of neurological disorders.
These research findings were the result of cooperation of various science and technology institutes: KAIST, Yonsei-IBS (Institute for Basic Science), Kyung Hee University, Sungkyunkwan University, KIST, University of Zurich in Switzerland, and Albert-Ludwigs-University Freiburg in Germany.
Schematic Image of Controlling the Synaptic Exocytotic Pathway by 5-IP7 , Helping the Understanding of the Signaling Mechanisms of Inositol Pyrophosphates
2016.07.21 View 12325