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Electron Heating in Weakly Ionized Collisional Plasmas
(from left: Professor Wonho Choe and Research Professor Sanghoo Park)
A KAIST research team successfully identified the underlying principles behind electron heating, which is one of the most important phenomena in plasmas. As the electric heating determines wide range of physical and chemical properties of plasmas, this outcome will allow relevant industries to extend and effectively customize a range of plasma characteristics for their specific needs.
Plasma, frequently called the fourth state of matter, can be mostly formed by artificially energizing gases in standard temperature (25°C) and pressure (1 atm) range. Among the many types of plasma, atmospheric-pressure plasmas have been gaining a great deal of attention due to their unique features and applicability in various scientific and industrial fields.
Because plasma characteristics strongly depends on gas pressure in the sub-atmospheric to atmospheric pressure range, characterizing the plasma at different pressures is a prerequisite for understanding the fundamental principles of plasmas and for their industrial applications.
In that sense, information on the spatio-temporal evolution in the electron density and temperature is very important because various physical and chemical reactions within a plasma arise from electrons. Hence, electron heating has been an interesting topic in the field of plasma.
Because collisions between free electrons and neutral gases are frequent under atmospheric-pressure conditions, there are physical limits to measuring the electron density and temperature in plasmas using conventional diagnostic tools, thus the principles behind free electron heating could not be experimentally revealed.
Moreover, lacking information on a key parameter of electron heating and its controlling methods is troublesome and limit improving the reactivity and applicability of such plasmas.
To address these issues, Professor Wonho Choe and his team from the Department of Nuclear and Quantum Engineering employed neutral bremsstrahlung-based electron diagnostics in order to accurately examine the electron density and temperature in target plasmas. In addition, a novel imaging diagnostics for two dimensional distribution of electron information was developed.
Using the diagnostic technique they developed, the team measured the nanosecond-resolved electron temperature in weakly ionized collisional plasmas, and they succeeded in revealing the spatiotemporal distribution and the fundamental principle involved in the electron heating process.
The team successfully revealed the fundamental principle of the electron heating process under atmospheric to sub-atmospheric pressure (0.25-1atm) conditions through conducting the experiment on the spatiotemporal evolution of electron temperature.
Their findings of the underlying research data on free electrons in weakly ionized collisional plasmas will contribute to enhancing the field of plasma science and their commercial applications.
Professor Choe said, “The results of this study provide a clear picture of electron heating in weakly ionized plasmas under conditions where collisions between free electrons and neutral particles are frequent. We hope this study will be informative and helpful in utilizing and commercializing atmospheric-pressure plasma sources in the near future.”
Articles related to this research, led by Research Professor Sanghoo Park, were published in Scientific Reports on May 14 and July 5.
Figure 1. Nanosecond-resolved visualization of the electron heating structure. Spatiotemporal evolution of 514.5-nm continuum radiation,Te, Ar I emission
Figure 2. Nanosecond-resolved visualization of electron heating. Spatiotemporal evolution of neutral bremsstrahlung at 514.5 nm
2018.09.10 View 7399 -
There Won't Be a Singularity: Professor Jerry Kaplan
(Professor Jerry Kaplan gave a lecture titled, Artificial Intelligence: Think Again at KAIST)
“People are so concerned about super intelligence, but the singularity will not happen,” said Professor Jerry Kaplan at Stanford University, an AI guru and Silicon Valley entrepreneur during a lecture at KAIST. He visited KAIST to give a lecture on Artificial Intelligence: Think Again on September 6.
Professor Kaplan said that some people argue that Korea’s AI research is behind the US and China but he doesn’t agree with that. “Korea is the most digitally connected one and has the world’s best engineers in the field. Korean companies are building products the consumers really like at reasonable prices. Those are attracting global consumers,” he added.
Instead of investing loads of money on AI research, he suggested three tasks for Korea taking a better position in the field of AI: Collecting and saving lots of data; training engineers, not the research talents in AI; and investing in AI infrastructure and relieving regulations by the government.
Referring to AI hype, Professor Kaplan argued that machines are intelligent, but they do not think in the way humans can, and assured the audience that the singularity some futurists predict will not be coming. He said, “Machine learning is a tool extracting useful information, but it does not mean they are so smart that they are taking over the world.”
(Professor Jerry Kaplan gave a lecture titled, Artificial Intelligence: Think Again at KAIST)
But what has made us believing AI myths? He first began pointing out how AI has been mythicized by three major drivers. Those are the entertainment industry, the popular media, and the AI community all wanting to attract more public attention and prestige. The abovementioned drivers are falsely making robots more human and are adding human characteristics.
Instead of being captivated by those AI myths and thinking about how to save the world from robots, he strongly argued, “We need to develop standards for the unintended side effects from AI.” To provide machines socially and ethically mingling with the human world, he believed principles should be set as follows: Define the Safe Operating Envelope (SOE), “safe modes” when out of bounds, study human behavior programmatically, certification and licensing standards, limitations on machine “agency,” and basic computational ethics such as when it is okay to break the law.
Professor Kaplan gave a positive view of AI for humans. “The future will be bright, thanks to AI. They do difficult work and help us and that will drive wealth and quality of life. The rich might get richer, but the benefits will spread throughout the people. It is time to think of innovative ways for using AI for building better world,” he concluded.
2018.09.10 View 5909 -
NEREC Summer Program Keeps Fellows Thinking, Engaged in Nuclear Nonproliferation
Nuclear technology is more than just technology. It is the fruit of the most advanced science and technology. It also requires high standards of policymaking and global cooperation for benefiting the technology.
As part of the fifth annual Nuclear Nonproliferation Education and Research Center (NEREC) Summer Fellows Program at KAIST, 24 students from 15 countries participated in six-week intensive education and training program. NEREC is the only university-based center dedicated to nuclear nonproliferation education and research established in 2014.
The program, which provides multidisciplinary lectures and seminars on nuclear technology and policy as well as international relations, was designed to nurture global nuclear technology experts well equipped in three areas: in-depth knowledge of technology, applicability gained from sound policy building, and negotiating for international cooperation. It now has grown into the most popular summer program at KAIST.
During the program from July 6 to August 18, participants were able to engage in enriching and stimulating learning experiences in tandem with policies and technology for the utilization and provision of peaceful and safe nuclear technology.
Participating fellows also had to conduct a group research project on a given topic. This year, they explored nuclear nonproliferation issues in relation to nuclear exports and brainstormed some recommendations for current policy. They presented their outcomes at the 2018 NEREC Conference on Nuclear Nonproliferation. After intensive lecture sessions and group research work, the fellows went off to key policy think-tanks, nuclear research institutes, and research power facilities in Korea, Japan, and China.
“NEREC emphasizes nuclear nonproliferation issues related to civilian nuclear power and the associated nuclear fuel cycle development from the point of technology users. I am very glad that the number of participants are increasing year by year,” said the Director of NEREC Man-Sung Yim, a professor in the Department of Nuclear and Quantum Engineering.
Participants’ majors vary from nuclear engineering to international relations to economics. The fellows divided into two groups of graduate and undergraduate courses. They expressed their deep satisfactory in the multidisciplinary lectures by scholars from KAIST, Seoul National University, and Korea National Defense University.
Many participants reported that they learned a lot, not only about policy and international relations but on the research they are conducting and what the key issues will be in dealing for producing meaningful research work.
Moad Aldbissi from the KTH Royal Institute of Technology is one of the students who shared the same view. He said, “Coming from a technical background in nuclear engineering, I managed to learn a lot about nuclear policy and international relations. The importance of integrating the technical and political fields became even clearer.”
Most students concurred that they recognized how important it was to make international collaboration in this powerful field for each country through this program.
“As an engineering student, I just approached this program like an empty glass in policy areas. While working with colleagues during the program, I came to understand how important it is to make cooperation in these fields for the better result of national development and international relations,” said Thanataon Pornphatdetaudom from the Tokyo Institute of Technology.
To Director Yim, this program is becoming well positioned to educate nuclear policy experts in a number of countries of strategic importance. He believes the continuous supply of these experts will contribute to promoting global nuclear nonproliferation and the peaceful use of nuclear energy while the use of nuclear technology continues.
2018.09.04 View 11860 -
Adding Smart to Science Museum
KAIST and the National Science Museum (NSM) created an Exhibition Research Center for Smart Science to launch exhibitions that integrate emerging technologies in the Fourth Industrial Revolution, including augmented reality (AR), virtual reality (VR), Internet of Things (IoTs), and artificial intelligence (AI).
There has been a great demand for a novel technology for better, user-oriented exhibition services. The NSM continuously faces the problem of not having enough professional guides. Additionally, there have been constant complaints about its current mobile application for exhibitions not being very effective.
To tackle these problems, the new center was founded, involving 11 institutes and universities. Sponsored by the National Research Foundation, it will oversee 15 projects in three areas: exhibition-based technology, exhibition operational technology, and exhibition content.
The group first aims to provide a location-based exhibition guide system service, which allows it to incorporate various technological services, such as AR/VR to visitors. An indoor locating system named KAILOS, which was developed by KAIST, will be applied to this service. They will also launch a mobile application service that provides audio-based exhibition guides.
To further cater to visitors’ needs, the group plans to apply a user-centered ecosystem, a living lab concept to create pleasant environment for visitors.
“Every year, hundred thousands of young people visit the National Science Museum. I believe that the exhibition guide system has to be innovative, using cutting-edge IT technology in order to help them cherish their dreams and inspirations through science,” Jeong Heoi Bae, President of Exhibition and Research Bureau of NSM, emphasized.
Professor Dong Soo Han from the School of Computing, who took the position of research head of the group, said, “We will systematically develop exhibition technology and contents for the science museum to create a platform for smart science museums. It will be the first time to provide an exhibition guide system that integrates AR/VR with an indoor location system.”
The center will first apply the new system to the NSM and then expand it to 167 science museums and other regional museums.
2018.09.04 View 10166 -
Potential Drug to Cure Ciliopathies
(from left: Professor Joon Kim and PhD candidate Yong Joon Kim)
Ciliopathies are rare disorders involving functional and structural abnormalities of cilia. Although they are rare, they may reach 1 in 1,000 births. Unfortunately, there are no small-molecule drugs for treating ciliary defects. A KAIST research team conducted successful research that introduces a potential treatment that will be a foundation for developing drugs to treat the disease as well as a platform for developing small-molecule drugs for similar genetic disorders.
It was found that mutations in genes required for the formation or function of primary cilia cause ciliopathies and they result in cerebellar disorders, kidney dysfunction, and retinal degeneration.
Primary cilia are cell organelles playing a crucial role in the human body. They participate in intercellular signal transduction during embryonic development and allow retinal photoreceptor cells to function.
Currently, there are no approved drugs available for treating most ciliopathies. In fact, this is the case for most of the rare genetic disorders involving functional abnormalities through genetic mutation, and gene therapy is usually the only treatment available.
To tackle this issue, a team led by Professor Joon Kim from the Graduate School of Medical Science and Engineering and Ho Jeong Kwon from Yonsei University constructed a cell that mimics a gene-mutated CEP290, one of the main causes of ciliopathies, through genome editing. They then used cell-based compound library screening to obtain a natural small-molecule compound capable of relieving defects in ciliogenesis, the production of cilia.
The CEP290 protein forms a complex with a ciliopathy protein called NPHP5 to support the function of the ciliary transition zone. In cases where the CEP290 protein is not formed due to a genetic mutation, NPHP5 will not function normally. Here, the compound was confirmed to partially restore the function of the complex by normalizing the function of NPHP5.
The team also identified that the compound is capable of retarding retinal degeneration by injecting the compound into animal models.
As a result, they discovered a lead compound for developing medication to treat ciliopathy patients involving retinal degeneration. Hence, the findings imply that chemical compounds that target other proteins interacting with the disease protein can mitigate shortages of a disease protein in recessive genetic disorders.
PhD candidate Yong Joon Kim stated, “This study shows how genetic disorders caused by genetic mutation can be treated with small-molecule drugs.”
Professor Kim said, “Since the efficacy of the candidate drug has been verified through animal testing, a follow-up study will also be conducted to demonstrate the effect on humans.”
This research was published in the Journal of Clinical Investigation on July 23.
Figure 1. Identification of compounds that rescue ciliogenesis defects caused by CEP290 knockout
Figure 2. Eupatilin injection ameliorates M-opsin trafficking and electrophysiological response of cone photoreceptors in rd16 mice
2018.08.30 View 8737 -
Improved Efficiency of CQD Solar Cells Using an Organic Thin Film
(from left: Professor Jung-Yong Lee and Dr. Se-Woong Baek)
Recently, the power conversion efficiency (PCE) of colloidal quantum dot (CQD)-based solar cells has been enhanced, paving the way for their commercialization in various fields; nevertheless, they are still a long way from being commercialized due to their efficiency not matching their stability. In this research, a KAIST team achieved highly stable and efficient CQD-based solar cells by using an amorphous organic layer to block oxygen and water permeation.
CQD-based solar cells are light-weight, flexible, and they boost light harvesting by absorbing near-infrared lights. Especially, they draw special attention for their optical properties controlled efficiently by changing the quantum dot sizes. However, they are still incompatible with existing solar cells in terms of efficiency, stability, and cost. Therefore, there is great demand for a novel technology that can simultaneously improve both PCE and stability while using an inexpensive electrode material.
Responding to this demand, Professor Jung-Yong Lee from the Graduate School of Energy, Environment, Water and Sustainability and his team introduced a technology to improve the efficiency and stability of CQD-based solar cells.
The team found that an amorphous organic thin film has a strong resistance to oxygen and water. Using these properties, they employed this doped organic layer as a top-hole selective layer (HSL) for the PbS CQD solar cells, and confirmed that the hydro/oxo-phobic properties of the layer efficiently protected the PbS layer. According to the molecular dynamics simulations, the layer significantly postponed the oxygen and water permeation into the PbS layer. Moreover, the efficient injection of the holes in the layer reduced interfacial resistance and improved performance.
With this technology, the team finally developed CQD-based solar cells with excellent stability. The PCE of their device stood at 11.7% and maintained over 90% of its initial performance when stored for one year under ambient conditions.
Professor Lee said, “This technology can be also applied to QD LEDs and Perovskite devices. I hope this technology can hasten the commercialization of CQD-based solar cells.”
This research, led by Dr. Se-Woong Baek and a Ph.D. student, Sang-Hoon Lee, was published in Energy & Environmental Science on May 10.
Figure 1. The schematic of the equilibrated structure of the amorphous organic film
Figure 2. Schematic illustration of CQD-based solar cells and graphs showing their performance
2018.08.27 View 8736 -
Robotic Herding of a Flock of Birds Using Drones
A joint team from KAIST, Caltech, and Imperial College London, presents a drone with a new algorithm to shepherd birds safely away from airports
Researchers made a new algorithm for enabling a single robotic unmanned aerial vehicle to herd a flock of birds away from a designated airspace. This novel approach allows a single autonomous quadrotor drone to herd an entire flock of birds away without breaking their formation.
Professor David Hyunchul Shim at KAIST in collaboration with Professor Soon-Jo Chung of Caltech and Professor Aditya Paranjape of Imperial College London investigated the problem of diverting a flock of birds away from a prescribed area, such as an airport, using a robotic UVA. A novel boundary control strategy called the m-waypoint algorithm was introduced for enabling a single pursuer UAV to safely herd the flock without fragmenting it.
The team developed the herding algorithm on the basis of macroscopic properties of the flocking model and the response of the flock. They tested their robotic autonomous drone by successfully shepherding an entire flock of birds out of a designated airspace near KAIST’s campus in Daejeon, South Korea. This study is published in IEEE Transactions on Robotics.
“It is quite interesting, and even awe-inspiring, to monitor how birds react to threats and collectively behave against threatening objects through the flock. We made careful observations of flock dynamics and interactions between flocks and the pursuer. This allowed us to create a new herding algorithm for ideal flight paths for incoming drones to move the flock away from a protected airspace,” said Professor Shim, who leads the Unmanned Systems Research Group at KAIST.
Bird strikes can threaten the safety of airplanes and their passengers. Korean civil aircraft suffered more than 1,000 bird strikes between 2011 and 2016. In the US, 142,000 bird strikes destroyed 62 civilian airplanes, injured 279 people, and killed 25 between 1990 and 2013. In the UK in 2016, there were 1,835 confirmed bird strikes, about eight for every 10,000 flights. Bird and other wildlife collisions with aircraft cause well over 1.2 billion USD in damages to the aviation industry worldwide annually. In the worst case, Canadian geese knocked out both engines of a US Airway jet in January 2009. The flight had to make an emergency landing on the Hudson River.
Airports and researchers have continued to reduce the risk of bird strikes through a variety of methods. They scare birds away using predators such as falcons or loud noises from small cannons or guns. Some airports try to prevent birds from coming by ridding the surrounding areas of crops that birds eat and hide in.
However, birds are smart. “I was amazed with the birds’ capability to interact with flying objects. We thought that only birds of prey have a strong sense of maneuvering with the prey. But our observation of hundreds of migratory birds such as egrets and loons led us to reach the hypothesis that they all have similar levels of maneuvering with the flying objects. It will be very interesting to collaborate with ornithologists to study further with birds’ behaviors with aerial objects,” said Professor Shim. “Airports are trying to transform into smart airports. This algorithm will help improve safety for the aviation industry. In addition, this will also help control avian influenza that plagues farms nationwide every year,” he stressed.
For this study, two drones were deployed. One drone performed various types of maneuvers around the flocks as a pursuer of herding drone, while a surveillance drone hovered at a high altitude with a camera pointing down for recording the trajectories of the pursuer drone and the birds.
During the experiments on egrets, the birds made frequent visits to a hunting area nearby and a large number of egrets were found to return to their nests at sunset. During the time, the team attempted to fly the herding drone in various directions with respect to the flock.
The drone approached the flock from the side. When the birds noticed the drone, they diverted from their original paths and flew at a 45˚ angle to their right. When the birds noticed the drone while it was still far away, they adjusted their paths horizontally and made smaller changes in the vertical direction. In the second round of the experiment on loons, the drone flew almost parallel to the flight path of a flock of birds, starting from an initial position located just off the nominal flight path. The birds had a nominal flight speed that was considerably higher than that of the drone so the interaction took place over a relatively short period of time.
Professor Shim said, “I think we just completed the first step of the research. For the next step, more systems will be developed and integrated for bird detection, ranging, and automatic deployment of drones.” “Professor Chung at Caltech is a KAIST graduate. And his first student was Professor Paranjape who now teaches at Imperial. It is pretty interesting that this research was made by a KAIST faculty member, an alumnus, and his student on three different continents,” he said.
(Figure A. Case 1: drone approaches the herd with sufficient distance to induce horizontal deviation)
(Figure B. Case 2: drone approaches the herd abruptly to cause vertical deviation)
2018.08.23 View 10300 -
Computer Simulation Identifies a Key Principle for Next-generation Carbon Fibers
(from left: Professor Yong-Hoon Kim and PhD candidate Juho Lee)
Performing state-of-the-art computer simulations, a KAIST research team identified an atomistic design principle to produce high-quality, next-generation carbon fibers.
Carbon fibers are light-weight yet excellent in mechanical strength and thermal resistance. Boasting these properties, they can be diversely applied in high-technology sectors, including automotive, aerospace, and nuclear engineering.
They are produced from a polymer precursor through a series of spinning, stabilization, and carbonization processes. However, there is a major obstacle to producing high-quality carbon fibers. That is, when there exist ill-defined regions within the polymer matrixes, they result in disorder and defects within the produced carbon fibers.
As a solution to this problem, it was proposed that the introduction of carbon nanotubes (CNT) could enhance polymer orientation and crystallization. However, although the alignment geometry of the CNT-polymer interface apparently affects the quality of produced fibers, the atomistic understanding of the CNT-polymer interface has been so far lacking, hindering further developments.
To clarify the nature of CNT-polymer interactions, Professor Yong-Hoon Kim from the Graduate School of Energy, Environment, Water and Sustainability and his team employed a multiscale approach that combines first-principles density functional theory (DFT) calculations and force-fields molecular dynamics (MD) simulations and revealed the unique structural and electronic characteristics of polymer-CNT interfaces.
Here, they studied polyacrylonitrile (PAN)-CNT hybrid structures as a representative case of polymer-CNT composites. PAN is the most common polymer precursor, taking more than 90% of carbon fiber production.
Based on their DFT calculations, the team showed that the lying-down PAN configurations give a larger PAN-CNT binding energy than their standing-up counterparts. Moreover, maximizing the lying-down PAN configuration was shown to allow linear alignments of PANs on CNT, enabling the desirable ordered long-range PAN-PAN packing.
They also identified the CNT curvature as another significant factor, giving the largest PAN-CNT binding energy in the zero-curvature graphene limit. Conducting large-scale MD simulations, they then demonstrated that graphene nanoribbons are a promising carbon nano-reinforcement candidate by explicitly showing its strong propensity to induce linear alignments of PANs adsorbed on them.
Professor Kim said, “This research can be an exemplary case where the quantum mechanical simulations identify basic principles for developing advanced materials. Computer simulation studies will play an increasingly greater role thanks to the advances in the simulation theory and computer performance.”
This research, carried out by the PhD candidate Juho Lee, was published in the inside back cover of Advanced Functional Materials on April 11.
Figure 1. Inside back cover of Advanced Functional Materials
Figure 2. Research outline
2018.08.03 View 8742 -
Visualizing Chemical Reaction on Bimetal Surfaces
Catalysts are the result of many chemists searching to unravel the beauty of molecules and the mystery of chemical reactions. Professor Jeong Young Park from the Department of Chemistry, whose research focuses on catalytic chemical reactions, is no exception. His research team recently made breakthroughs in addressing long-standing questions for understanding reaction mechanisms on bimetal catalysts.
During the studies reported in Science Advances, following a publication in Nature Communications this month, Professor Park’s research team identified that the formation of metal–oxide interfaces is the key factor responsible for the synergistic catalytic effect in bimetal catalysts. The team confirmed this fundamental reaction mechanism through in situ imaging of reaction conditions. This is the first visualization of bimetal surfaces under reaction conditions, signifying the role of metal–oxide interfaces in heterogeneous catalysis.
Bimetallic materials have outstanding catalytic performance, which opens a new pathway for controlling electronic structures and binding energy in catalysts. Despite considerable research on various catalytic reaction efficiencies, there are yet unanswered questions on the underlying principles behind the improved performance. Even more, it was very hard to figure out what led to the efficiency because the structure, chemical composition, and oxidation state of bimetallic materials change according to reaction conditions.
Recently, some research groups suggested that oxide–metal interfacial sites formed by the surface segregation of bimetallic nanoparticles might be responsible for the increased catalytic performance. However, they failed to present any definitive evidence illustrating the physical nature or the fundamental role of the oxide–metal interfaces leading to the improved performance.
To specifically address this challenge, the research team carried out in situ observations of structural modulation on platinum–nickel bimetal catalysts under carbon monoxide oxidation conditions with ambient pressure scanning tunneling microscopy and ambient pressure X-ray photoelectron spectroscopy.
The team observed that platinum–nickel bimetal catalysts exhibited a variety of different structures depending on the gas conditions. Under ultrahigh vacuum conditions, the surface exhibited a platinum skin layer on the platinum–nickel alloyed surface, selective nickel segregation followed by the formation of nickel oxide clusters using oxygen gas, and finally the coexistence of nickel oxide clusters on the platinum skin during carbon monoxide oxidation. The research team found that the formation of interfacial platinum–nickel oxide nanostructures is responsible for a highly efficient step in the carbon monoxide oxidation reaction.
These findings illustrate that the enhancement of the catalytic activity on the bimetallic catalyst surface originates from the thermodynamically efficient reaction pathways at the metal–metal oxide interface, which demonstrates a straightforward process for the strong metal–support interaction effect. The formation of these interfacial metal–metal oxide nanostructures increases catalytic activity while providing a thermodynamically efficient reaction pathway by lowering the heat of the reactions on the surface. [J. Kim et al. Adsorbate-driven reactive interfacial Pt-NiO1-x nanostructure formation on the Pt3Ni(111) alloy surface, Science Advances (DOI: 10.1126/sciadv.aat3151 ]
Professor Park said that one way to monitor catalysts is to detect hot electrons associated with energy dissipation and conversion processes during surface reactions. His team led the real-time detection of hot electrons generated on bimetallic PtCo nanoparticles during exothermic hydrogen oxidation. The team successfully clarified the origin of the synergistic catalytic activity of PtCo nanoparticles with corresponding chemicurrent values.
By estimating the chemicurrent yield, the research team conclude that the catalytic properties of the bimetallic nanoparticles are strongly governed by the oxide–metal interface, which facilitates hot electron transfer. [H. Lee et al. Boosting hot electron flux and catalytic activity at metal–oxide interfaces of PtCo bimetallic nanoparticles, Nature Comm, 9, 2235 (2018)].
Professor Park explained, “We feel that the precise measurement of hot electrons on catalysts gives insight into the mechanism for heterogeneous catalysis, which can help with the smart design of highly reactive materials. The control of catalytic activity via electronic engineering of catalysts is a promising prospect that may open the door to the new field of combining catalysis with electronics, called “catalytronics.” He added that the study also establishes a strategy for improving catalytic activity for catalytic reactions in industrial chemical reactors.
Professors Park and Yousung Jung from the Department of Chemical and Biomolecular Engineering and the Graduate School of EEWS conducted this research in collaboration with Professor Bongjin Mun from the Department of Physics at GIST.
Figure 1. Evolution of surface structures of PtNi bimetal surfaces under various ambient conditions.
Figure 2. Formation of Pt-CoO interface leads to the catalytic enhancement of PtCo bimetal catalysts.
2018.07.25 View 10625 -
It's Time to 3D Sketch with Air Scaffolding
People often use their hands when describing an object, while pens are great tools for describing objects in detail. Taking this idea, a KAIST team introduced a new 3D sketching workflow, combining the strengths of hand and pen input. This technique will ease the way for ideation in three dimensions, leading to efficient product design in terms of time and cost.
For a designer's drawing to become a product in reality, one has to transform a designer's 2D drawing into a 3D shape; however, it is difficult to infer accurate 3D shapes that match the original intention from an inaccurate 2D drawing made by hand. When creating a 3D shape from a planar 2D drawing, unobtainable information is required. On the other hand, loss of depth information occurs when a 3D shape is expressed as a 2D drawing using perspective drawing techniques.
To fill in these “missing links” during the conversion, "3D sketching" techniques have been actively studied. Their main purpose is to help designers naturally provide missing 3D shape information in a 2D drawing. For example, if a designer draws two symmetric curves from a single point of view or draws the same curves from different points of view, the geometric clues that are left in this process are collected and mathematically interpreted to define the proper 3D curve. As a result, designers can use 3D sketching to directly draw a 3D shape as if using pen and paper.
Among 3D sketching tools, sketching with hand motions, in VR environments in particular, has drawn attention because it is easy and quick. But the biggest limitation is that they cannot articulate the design solely using rough hand motions, hence they are difficult to be applied to product designs. Moreover, users may feel tired after raising their hands in the air during the entire drawing process.
Using hand motions but to elaborate designs, Professor Seok-Hyung Bae and his team from the Department of Industrial Design integrated hand motions and pen-based sketching, allocating roles according to their strengths. This new technique is called Agile 3D Sketching with Air Scaffolding. Designers use their hand motions in the air to create rough 3D shapes which will be used as scaffolds, and then they can add details with pen-based 3D sketching on a tablet (Figure 1).
Figure 1. In the agile 3D sketching workflow with air scaffolding, the user (a) makes unconstrained hand movements in the air to quickly generate rough shapes to be used as scaffolds, (b) uses the scaffolds as references and draws finer details with them, (c) produces a high-fidelity 3D concept sketch of a steering wheel in an iterative and progressive manner.
The team came up with an algorithm to identify descriptive hand motions from transitory hand motions and extract only the intended shapes from unconstrained hand motions, based on air scaffolds from the identified motions.
Through user tests, the team identified that this technique is easy to learn and use, and demonstrates good applicability. Most importantly, the users can reduce time, yet enhance the accuracy of defining the proportion and scale of products.
Eventually, this tool will be able to be applied to various fields including the automobile industry, home appliances, animations and the movie making industry, and robotics. It also can be linked to smart production technology, such as 3D printing, to make manufacturing process faster and more flexible.
PhD candidate Yongkwan Kim, who led the research project, said, “I believe the system will enhance product quality and work efficiency because designers can express their 3D ideas quickly yet accurately without using complex 3D CAD modeling software. I will make it into a product that every designer wants to use in various fields.”
“There have been many attempts to encourage creative activities in various fields by using advanced computer technology. Based on in-depth understanding of designers, we will take the lead in innovating the design process by applying cutting-edge technology,” Professor Bae added.
Professor Bae and his team from the Department of Industrial Design has been delving into developing better 3D sketching tools. They started with a 3D curve sketching system for professional designers called ILoveSketch and moved on to SketchingWithHands for designing a handheld product with first-person hand postures captured by a hand-tracking sensor. They then took their project to the next level and introduced Agile 3D Sketching with Air Scaffolding, a new 3D sketching workflow combining hand motion and pen drawing which was chosen as one of the CHI (Conference on Human Factors in Computing Systems) 2018 Best Papers by the Association for Computing Machinery.
- Click the link to watch video clip of SketchingWithHands
2018.07.25 View 10142 -
A New Efficient Oxide Coating Technology to Improve Fuel Cells
A new efficient oxide coating technology that can be applied in less than five minutes could lead to dramatic improvements in the lifetime and performance of fuel cells. The fundamental principle behind this approach is maximizing the oxygen reduction reaction site of a platinum thin-film electrode, preventing the electrodes from aggregating at high temperatures.
Fuel cells have emerged as a clean electricity generation system that does not pollute the air. In particular, solid oxide fuel cells (SOFCs) are beginning to gain a great deal of attention due to their higher power generation efficiency compared to other fuel cells. It is also advantageous to use other power sources than expensive hydrogen fuel.
However, the high costs and insufficient lifetimes caused by high temperatures needed to operate the solid oxide fuel cells have remained significant challenges to commercialization.
Recently, attempts to lower the operating temperature (< 600°C) of these devices by introducing thin-film processes have drew attention of researchers, with the resulting products known as thin-film-based solid oxide fuel cells.
In order to create enhanced device performance at lower temperatures, the research team, led by Professor WooChul Jung in the Department of Materials Science and Engineering, applied and developed oxide coating technology to maximize the oxygen reduction reaction sites of a platinum thin-film electrode and to prevent platinum electrodes from thermal aggregating.
The team succeeded in over-coating a platinum electrode with a new coating material called praseodymium-doped ceria (Pr,Ce)O2-, which has high conductivity for both electrons and oxygen ions and excellent catalytic properties for oxygen reduction reactions. As a result, electrode resistance was reduced by more than 1000 times, creating the potential for these electrodes to be used in high-temperature electrochemical cells.
In addition, they proposed that the high performance of thin-film-based oxide fuel cells’ oxygen electrodes could be realized through the nano-structuring of (Pr,Ce)O2-δ without any platinum.
Professor Jung said, “The electrode coating technology used in this study is of great technical value because of the utilization of affordable and mass-produced electrochemical deposition.” He added, “In the future, this technology will be feasible for replacing platinum electrodes in thin-film-based oxide fuel cells, and we expect that the affordable prices of this fuel cell will eventually boost market competitiveness.”
This research was described in Advanced Energy Materials in July and was featured as the Inside Front Cover and video abstract. It was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Korea Electric Power Corporation (KEPCO) Research Institute.
Figure 1. The change of electrode activity with and without overcoated (Pr,Ce)O2-δ nanostructures.
2018.07.18 View 8831 -
Enhanced PDT to Cure Cancer with Fewer Side Effects
(From left: PhD candidate Ilkoo Noh and Professor Yeu-Chun Kim)
A KAIST research team developed near-infrared fluorophores-based photodynamic therapy (PDT) that reduced the downside of existing PDTs.
PDT is a way to cure wounds with lasers instead of drug treatment. When a laser irradiates a targeted site, a photosensitizer (PS) absorbs light energy and then converts oxygen to singlet oxygen or free radicals, leading to programmed cell death. This treatment has been used widely in clinical fields, especially for skin disease because it allows noninvasive treatment.
However, the existing PDTs have limitations for first-line therapy because PDT agents can cause genetic variations when they have low efficiency, hence reducing treatment effects.
The key to enhancing the efficiency of PDTs is how much PS can be concentrated to a wanted site, which laser wavelength the PS is reacted to, and how fast the PS clears organelle after treatment.
Professor Yeu-Chun Kim and his team from the Department of Chemical and Biomolecular Engineering, in collaboration with Professor Ji-Ho Park from the Department of Bio and Brain Engineering, developed a new PS called mitochondria targeting photodynamic therapeutic agent (MitDt) to maximize PDT effects while reducing unwanted side effects.
Mitochondria has emerged as target sites to maximize the effects of PS since they play essential roles in metabolism and have high transmembrane potential.
According to the team, when mitochondria is photodamaged by reactive oxygen species (ROS) generated after laser irradiation, they immediately lose their mitochondrial membrane potential and initiate apoptosis. Therefore, combining the PDT agent with the mitochondrial targeting agent can result in rapid damage to cancer cells, improving therapeutic efficacy and reducing unwanted side effects.
To successfully apply mitochondria-targeting PS, the team developed near-infrared (NIR) region PDT agents, which can be used to treat deep-tissue level cancer due to the permeability of the NIR laser. Light scattering is also decreased, thus obtaining higher therapeutic efficacy.
However, there is a problem of generating singlet oxygen when irradiating with an NIR laser. To address this issue, the team developed a novel PS that combines a functionalized NIR dye and a mitochondria-targeting agent to gain the benefit of rapid organelle clearance after treatment and also remain in cancer mitochondria for a long time, amplifying the amount of ROS to the target sites irradiated by the laser.
To verify the efficacy, the team injected MitDt into tumor-bearing mice. They were irradiated with an NIR laser at 662 nm to induce cancer treatment and their cancer size was reduced up to three-fold.
PhD candidate Ilkoo Noh, who led this research said, “This enhanced photodynamic cancer treatment has the advantage of treating a wanted site without any side effects because this PS stays longer in a mitochondrial cancer cell. We also confirmed that the PS did not cause cytotoxicity.”
Professor Kim added, “This research outcome will reduce the danger of side effects and can be applied for treating various diseases”.
This research was chosen as the cover page of Advanced Science on March 25.
Figure 1. The cover of Advanced Science
Figure 2. a) Chemical structure of MitDt compounds (above) b) mitochondria localization of designed PS (left) and ROS generation after 662nm laser irradiation (right)
2018.07.16 View 7110