Chem
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Polymers with Highly Improved Light-transformation Efficiency
A joint Korean research team, led by Professor Bum-Joon Kim of the Department of Chemical and Biomolecular Engineering at KAIST and Professor Young-Woo Han of the Department of Nanofusion Engineering at Pusan National University, has developed a new type of electrically-conductive polymer for solar batteries with an improved light-transformation efficiency of up to 5%. The team considers it a viable replacement for existing plastic batteries for solar power which is viewed as the energy source of the future.
Polymer solar cells have greater structural stability and heat resistance compared to fullerene organic solar cells. However, they have lower light-transformation efficiency—below 4%—compared to 10% of the latter. The low efficiency is due to the failure of blending among the polymers that compose the active layer of the cell. This phenomenon deters the formation and movement of electrons and thus lowers light-transformation efficiency.
By manipulating the structure and concentration of conductive polymers, the team was able to effectively increase the polymer blending and increase light-transformation efficiency. The team was able to maximize the efficiency up to 6% which is the highest reported ratio.
Professor Kim said, “This research demonstrates that conductive polymer plastics can be used widely for solar cells and batteries for mobile devices.”
The research findings were published in the February 18th issue of the Journal of the American Chemical Society (JACS).
Picture: Flexible Solar Cell Polymer Developed by the Research Team
2015.04.05 View 11199 -
Mystery in Membrane Traffic How NSF Disassembles Single SNAR Complex Solved
KAIST researchers discovered that the protein N-ethylmaleimide-sensitive factor (NSF) unravels a single SNARE complex using one round ATP turnover by tearing the complex with a single burst, contradicting a previous theory that it unwinds in a processive manner.
In 2013, James E. Rothman, Randy W. Schekman, and Thomas C. Südhof won the Nobel Prize in Physiology or Medicine for their discoveries of molecular machineries for vesicle trafficking, a major transport system in cells for maintaining cellular processes. Vesicle traffic acts as a kind of “home-delivery service” in cells. Vesicles package and deliver materials such as proteins and hormones from one cell organelle to another. Then it releases its contents by fusing with the target organelle’s membrane. One example of vesicle traffic is in neuronal communications, where neurotransmitters are released from a neuron. Some of the key proteins for vesicle traffic discovered by the Nobel Prize winners were N-ethylmaleimide-sensitive factor (NSF), alpha-soluble NSF attachment protein (α-SNAP), and soluble SNAP receptors (SNAREs).
SNARE proteins are known as the minimal machinery for membrane fusion. To induce membrane fusion, the proteins combine to form a SNARE complex in a four helical bundle, and NSF and α-SNAP disassemble the SNARE complex for reuse. In particular, NSF can bind an energy source molecule, adenosine triphosphate (ATP), and the ATP-bound NSF develops internal tension via cleavage of ATP. This process is used to exert great force on SNARE complexes, eventually pulling them apart. However, although about 30 years have passed since the Nobel Prize winners’ discovery, how NSF/α-SNAP disassembled the SNARE complex remained a mystery to scientists due to a lack in methodology.
In a recent issue of Science, published on March 27, 2015, a research team, led by Tae-Young Yoon of the Department of Physics at the Korea Advanced Institute of Science and Technology (KAIST) and Reinhard Jahn of the Department of Neurobiology of the Max-Planck-Institute for Biophysical Chemistry, reports that NSF/α-SNAP disassemble a single SNARE complex using various single-molecule biophysical methods that allow them to monitor and manipulate individual protein complexes.
“We have learned that NSF releases energy in a burst within 20 milliseconds to “tear” the SNARE complex apart in a one-step global unfolding reaction, which is immediately followed by the release of SNARE proteins,” said Yoon.
Previously, it was believed that NSF disassembled a SNARE complex by unwinding it in a processive manner. Also, largely unexplained was how many cycles of ATP hydrolysis were required and how these cycles were connected to the disassembly of the SNARE complex.
Yoon added, “From our research, we found that NSF requires hydrolysis of ATPs that were already bound before it attached to the SNAREs—which means that only one round of an ATP turnover is sufficient for SNARE complex disassembly. Moreover, this is possible because NSF pulls a SNARE complex apart by building up the energy from individual ATPs and releasing it at once, yielding a “spring-loaded” mechanism.”
NSF is a member of the ATPases associated with various cellular activities family (AAA+ ATPase), which is essential for many cellular functions such as DNA replication and protein degradation, membrane fusion, microtubule severing, peroxisome biogenesis, signal transduction, and the regulation of gene expression. This research has added valuable new insights and hints for studying AAA+ ATPase proteins, which are crucial for various living beings.
The title of the research paper is “Spring-loaded unraveling of a single SNARE complex by NSF in one round of ATP turnover.” (DOI: 10.1126/science.aaa5267)
Youtube Link: https://www.youtube.com/watch?v=FqTSYHtyHWE&feature=youtu.be
Picture 1. Working model of how NSF/α-SNAP disassemble a single SNARE complex
Picture 2. After neurotransmitter release, NSF disassembles a single SNARE complex using a single round of ATP turnover in a single burst reaction.
2015.03.28 View 10985 -
KAIST Develops a Credit-Card-Thick Flexible Lithium Ion Battery
Since the battery can be charged wirelessly, useful applications are expected including medical patches and smart cards.
Professor Jang Wook Choi at KAIST’s Graduate School of Energy, Environment, Water, and Sustainability (EEWS) and Dr. Jae Yong Song at the Korea Research Institute of Standards and Science jointly led research to invent a flexible lithium ion battery that is thinner than a credit card and can be charged wirelessly.
Their research findings were published online in Nano Letters on March 6, 2015. Lithium ion batteries are widely used today in various electronics including mobile devices and electronic cars. Researchers said that their work could help accelerate the development of flexible and wearable electronics.
Conventional lithium ion batteries are manufactured based on a layering technology, stacking up anodes, separating films, and cathodes like a sandwich, which makes it difficult to reduce their thickness. In addition, friction arises between layers, making the batteries impossible to bend. The coating films of electrodes easily come off, which contributes to the batteries’ poor performance.
The research team abandoned the existing production technology. Instead, they removed the separating films, layered the cathodes and anodes collinearly on a plane, and created a partition between electrodes to eliminate potential problems, such as short circuits and voltage dips, commonly present in lithium ion batteries.
After more than five thousand consecutive flexing experiments, the research team confirmed the possibility of a more flexible electrode structure while maintaining the battery performance comparable to the level of current lithium ion batteries.
Flexible batteries can be applied to integrated smart cards, cosmetic and medical patches, and skin adhesive sensors that can control a computer with voice commands or gesture as seen in the movie “Iron Man.”
Moreover, the team has successfully developed wireless-charging technology using electromagnetic induction and solar batteries.
They are currently developing a mass production process to combine this planar battery technology and printing, to ultimately create a new paradigm to print semiconductors and batteries using 3D printers.
Professor Choi said, “This new technology will contribute to diversifying patch functions as it is applicable to power various adhesive medical patches.”
Picture 1: Medical patch (left) and flexible secondary battery (right)
Picture 2: Diagram of flexible battery
Picture 3: Smart card embedding flexible battery
2015.03.24 View 12655 -
Light Driven Drug-Enzyme Reaction Catalytic Platform Developed
Low Cost Dye Used, Hope for Future Development of High Value Medicinal Products to Treat Cardiovascular Disease and Gastric Ulcers
A KAIST research team from the Departments of Materials Science and Engineering and of Chemical and Biomolecular Engineering, led respectively by Professors Chan Beum Park and Ki Jun Jeong, has developed a new reaction platform to induce drug-enzyme reaction using light.
The research results were published in the journal Angewandte Chemie, International Edition, as the back cover on 12 January 2015.
Applications of this technology may enable production of high value products such as medicine for cardiovascular disease and gastric ulcers, for example Omeprazole, using an inexpensive dye.
Cytochrome P450 is an enzyme involved in oxidative response which has an important role in drug and hormone metabolism in organisms. It is known to be responsible for metabolism of 75% of drugs in humans and is considered a fundamental factor in new drug development.
To activate cytochrome P450, the enzyme must receive an electron by reducing the enzyme. In addition, NADPH (a coenzyme) needs to be present. However, since NADPH is expensive, the use of cytochrome P450 was limited to the laboratory and has not yet been commercialized.
The research team used photosensitizer eosin Y instead of NADPH to develop “Whole Cell Photo-Biocatalysis” in bacteria E. coli. By exposing inexpensive eosin Y to light, cytochrome P450 reaction was catalyzed to produce the expensive metabolic material.
Professor Park said, “This research enabled industrial application of cytochrome P450 enzyme, which was previous limited.” He continued, “This technology will help greatly in producing high value medical products using cytochrome P450 enzyme.”
The research was funded by the National Research Foundation of Korea and KAIST's High Risk High Return Project (HRHRP).
Figure 1: Mimetic Diagram of Electron Transfer from Light to Cytochrome P450 Enzyme via Eosin Y, EY
Figure 2: The back cover of Angewandte Chemie published on 12 January 2015, showing the research results
2015.01.26 View 10735 -
KAIST Announces the Recipients of Distinguished Alumni Awards
The KAIST Alumni Association (KAA) announced four “Proud KAIST Alumni” awards recipients for the year 2014: Sung-Wook Park, the Chief Executive Officer and President of SK Hynix; Seung Ho Shin, the President of Kangwon National University; Kew-Ho Lee, the President of the Korea Research Institute of Chemical Technology; and Mun-Kee Choi, the former Minister of Science, ICT and Future Planning of the Republic of Korea. The award ceremony took place during the 2015 KAA’s New Year's ceremony on January 17, 2015 at the Palace Hotel in Seoul.
Sung-Wook Park (M.S. ’82 and Ph.D. ’88, Department of Materials Science and Engineering), the Chief Executive Officer and President of SK Hynix, has worked as an expert in the field of memory semi-conductors for the past 30 years. He developed innovative technology and improved production efficiency, enabling the Korean semi-conductor industry to become a global leader.
Seung Ho Shin (M.S. ’79 and Ph.D. ’87, Department of Physics), the President of Kangwon National University (KNU), worked in the field of optical information processing, producing excellent research achievements and teaching the next generation of scientists. As the president of KNU, he has set an exemplary leadership in higher education.
Kew-Ho Lee (M.S. ’75, Department of Chemistry), the President of the Korea Research Institute of Chemical Technology, pioneered the field of separation film production which contributed greatly to Korean technological developments. He led several domestic and international societies to facilitate dynamic exchanges between industry and academia and with the international community.
Mun-Kee Choi (M.S. ’76, Department of Industrial and Systems Engineering), the former Minister of Science, ICT and Future Planning, the Republic of Korea, is a great contributor to the information and communications technology in Korea, working as a leader in the field of broadband integrated service digital network. He is also an educator for gifted students in science and technology, and a manager of the Electronics and Telecommunications Research Institute.
The Alumni Association established the “Proud KAIST Alumni Awards” in 1992 to recognize its alumni’s outstanding contributions to Korea and KAIST.
Pictured from left to right, Sung-Wook Park (the Chief Executive Officer and President of SK Hynix), Seung Ho Shin (the President of Kangwon National University), Kew-Ho Lee (the President of the Korea Research Institute of Chemical Technology), and Mun-Kee Choi (the former Minister of Science, ICT and Future Planning)
2015.01.19 View 14964 -
Nanoparticle Cluster Manufacturing Technique Using DNA Binding Protein Developed
Professor Hak-Sung Kim of the Department of Biological Sciences at KAIST and Yiseul Ryu, a doctoral candidate, used the Zinc Finger protein that specifically binds to target DNA sequence to develop a new manufacturing technique for size-controllable magnetic Nanoparticle Clusters (NPCs). Their research results were published in Angewandte Chemie International Edition online on 25 November 2014.
NPCs are structures consisting of magnetic nanoparticles, gold nanoparticles, and quantum dots, each of which are smaller than 100 nm (10-9m). NPCs have a distinctive property of collectivity not seen in single nanoparticles.
Specifically NPCS differ in physical and optical properties such as Plasmon coupling absorbance, energy transfers between particles, electron transfers, and conductivity. Therefore, NPCs can be employed in biological and medical research as well as the development of nanoelectric and nanoplasmon devices.
To make use of these novel properties, the size and the composition of the cluster must be exquisitely controlled. However, previous techniques relied on chemical binding which required complex steps, making it difficult to control the size and composition of NPCs.
Professor Kim’s team used Zinc Finger, a DNA binding protein, to develop a NPCs manufacturing technique to create clusters of the desired size easily. The Zinc Finger protein contains a zinc ion and specifically recognizes DNA sequence upon binding, which allows the exquisite control of the size and the cluster composition. The technique is also bio-friendly.
Professor Kim’s team created linear structure of different sizes of NPCs using Zinc Finger proteins and three DNA sequences of different lengths. The NPCs they produced confirmed their ability to control the size and structure of the cluster by using different DNA lengths.
The NPCs showed tripled T2 relaxation rates compared to the existing MRI contrast media (Feridex) and effectively transported to targeted cells. The research findings show the potential use of NPCs in biological and medical fields such as MRI contrast media, fluorescence imaging, and drug transport.
The research used the specific binding property of protein and DNA to develop a new method to create an inorganic nanoparticle’s supramolecular assembly. The technique can be used and applied extensively in other nanoparticles for future research in diagnosis, imaging, and drug and gene delivery.
Figure 1. A Mimetic Diagram of NPCs Manufacturing Technique Using DNA Binding Protein Zinc Finger
Figure 2. Transmission Electron Microscopy Images showing different sizes of NPCs depending on the length of the DNA
2014.12.04 View 13333 -
Elsevier Selects a KAIST Graduate's Paper as the Top Cited Papers in 2011-2012
Dr. Myung-Won Seo, a graduate from the Department of Chemical and Bimolecular Engineering at KAIST, published a paper in January 2011 in Chemical Engineering Journal, which was entitled “Solid Circulation and Loop-seal Characteristics of a Dual Circulating Fluidized Bed: Experiments and CFD Simulation.” His paper was selected by Elsevier as the Top Cited Papers of 2011-2012. The Chemical Engineering Journal is a renowned peer-reviewed journal issued by Elsevier.
Dr. Seo published another paper, “CFD Simulation with Experiments in a Dual Circulating Fluidized Bed Gasifier,” in January 2012 in Computers & Chemical Engineering, which was also selected as the Most Downloaded Papers in 2012-2013.
Dr. Seo graduated with a doctoral degree from KAIST in 2011. He is currently working at the Clean Fuel Laboratory, the Korea Institute of Energy Research, Daejeon, as a researcher. His research areas are coal gasification, upgrading, and liquefaction, as well as energy and chemical production from low-grade fuels such as biomass and wastes.
2014.11.24 View 10025 -
Eggshell-like Cell Encapsulation and Degradation Technology Developed
Some bacteria form endospores on cell walls to protect their DNA in case of nutrient deficiency. When an endospore meets a suitable environment for survival, the cell can revert to the original state from which it can reproduce.
The technique that can artificially control such phenomenon was developed by an international team of researchers. At first, a cell is wrapped and preserved like an egg. When the cell is needed, the technique allows the endospore to decompose while it is alive. Future applications for this technique include cell-based biosensor, cell therapy, and biocatalyst processes.
Professors Insung Choi and Younghoon Lee from the Department of Chemistry at KAIST as well as and Professor Frank Caruso from the University of Melbourne developed this technique which permits a cell to stay alive by coating it with film on a nanometer scale and then to be decomposed while it is alive.
The research finding was published in the November 10th issue of Angewandte Chemie International Edition as the lead article.
Cell encapsulation allows researchers to capture a cell in a tight capsule while it is alive. It is highly recognized in cell-based applications where the control of cell stability and cell-division is the biggest issue.
Traditional cell encapsulation methods utilized organic film or inorganic capsules that are made of organic film moldings. Although these films tightly closed around the cell, because they were not easily decomposable, it was difficult to apply the method.
The research team succeeded in encapsulating each cell in a metal-polyphenol film by mixing tannic acid and iron ion solution with yeast cells.
Usually extracted from oak barks or grape peels, tannic acid is a natural substance. It forms a metal-polyphenol film within ten seconds when it meets iron ions due to its high affinity with cells. Cells encapsulated with this film presented high survival rates. Since the film forms quickly in a simple manner, it was possible to obtain large amount of encapsulated cells.
The research team also found that the metal-polyphenol film was stable in neutral pH, but is easily degradable under a weak acidic condition. Using this property, they were able to control cell division by restoring the cell to its pre-encapsulated state at a desired moment.
Protecting the cell from the external environment like an egg shell, the metal-polyphenol film protected the cell against foreign conditions such as lytic enzymes, extended exposure to UV radiation, and silver nanoparticles. The research indicated that the encapsulated cells had a high survival rate even under extreme environments.
Professor Lee said that “not only the cells remain alive during the encapsulation stage, but also they can be protected under extreme environment.” He added, “This is an advanced cell encapsulation technology that allows controlling cell-division of those cells through responsive shell degradation on-demand.”
Professor Choi commented, “Although the cell encapsulation technology is still in its infancy, as the technology matures the application of cell-manipulation technology will be actualized.” He highlighted that “it will serve as a breakthrough to problems faced by cell-based applications.”
Sponsored by the Ministry of Science, ICT and Future Planning and the National Research Foundation of Korea, the research was led by two Master’s candidates, Ji Hun Park and Kyung Hwan Kim, under the joint guidance of research professors from KAIST and the University of Melbourne.
Figure 1: Lead article of Angewandte Chemie
Background: Shows a live native yeast (in green) encapsulated in a metal-polyphenol film (in red) illustrating the vitality of the yeast
Front: A native yeast at each encapsulation stage
Pictured on the bottom left is a cell prior to encapsulation. Following the red arrow, the native yeast is in purple to show metal-polyphenol film formed around the cell. The cell after the green arrow is a visualization of the degradation of the film in weak acidic condition.
Figure 2: A mimetic diagram of cell encapsulation with a metal-polyphenol film
Top: A native yeast before encapsulation
Middle: A native yeast encapsulated with Tannic Acid-Fe (III) Nanoshell – cell-division of the encapsulated cell is controlled by pH and the shell is protected against silver nanoparticle, lytic enzyme, and UV-C
Bottom: Shell degradation on-demand depending on pH
2014.11.18 View 10625 -
Distinguished Professor Sang Yup Lee Accepts an Honorary Professorship at Beijing University of Chemical Technology
Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering at KAIST has been appointed an honorary professor at Beijing University of Chemical Technology (BUCT). Founded in 1958, BUCT is one of the outstanding universities in mainland China, especially in chemistry studies.
In addition to the Chinese Academy of Sciences (2012), Shanghai Jiao Tong University (2013), Wuhan University (2014), and Hebei University of Technology (2014), this is the fifth honorary professorship Professor Lee has received from higher education institutions in China.
Professor Lee was recognized for his pioneering research in systems metabolic engineering of microorganisms necessary for the development of green chemical industries. He succeeded in producing succinic acid through bacterial fermentation and engineering plastic raw materials in the most effective and economical method for the first time in the world. Professor Lee also developed polylactic acid, a bio-based polymer that allows plastics to be produced through natural and renewable resources, as well as the microbial production of alkanes, an alternative to gasoline that can be produced from fatty acids.
Professor Lee has been actively working as a member of a group of global leaders supported by the World Economic Forum (WEF), serving as the Chairman of the Future of Chemicals, Advanced Materials & Biotechnology, Global Agenda Councils, WEF.
2014.11.13 View 11958 -
Distinguished Professor Sang Yup Lee Gives Special Lecture at Tianjin University, China
Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering at KAIST gave a special lecture at Tianjin University, China, on September 12, 2014.
The university has invited prestigious scholars and scientists including Nobel Prize laureates from all around the world to their program called the "BeiYang Lecture Series."
Professor Lee said:
"The lecture series has invited many eminent global leaders such as Dr. Steven Chu, who received the Nobel Prize in Physics in 1997 and also served the 12th United States Secretary of Energy. It is a great honor to participate in the program as a speaker. The university told me that in recognition of my research in the development of sustainable biochemical industry through systems metabolic engineering, I was invited to speak.”
Professor Lee presented his speech entitled “Production of Chemical Materials through Microorganism Metabolic Systems Engineering” and took questions from the audience.
Professor Lee developed the world’s most efficient microorganism and bioprocess such as succinate, butanol, and engineering plastic raw materials. In recent years, he has succeeded in producing a small quantity of gasoline through converting in-vivo generated fatty acids.
2014.09.16 View 9643 -
President Steve Kang of KAIST Attends the 2014 Summer Davos Forum in Tianjin, China
President Steve Kang of KAIST will attend the 2014 Annual Meeting of the New Champions, the World Economic Forum (WEF), to be held on September 10-12, 2014 in Tianjin, China.
KAIST holds its own IdeasLab session on nanotechnology on September 12, 2014.
On September 10, 2014, President Steve Kang will participate in a private session hosted by the Global University Leaders Forum (GULF) community at WEF as a panelist.
In addition to President Kang, eight presidents from top global universities such as the National University of Singapore, Peking University, ETH Zurich (Swiss Federal Institute of Technology), University of Tokyo, and Carnegie Mellon University will join the panel discussion under the topic, “Increasing the Translational Impact of University Research.” Specifically, the presidents will address issues related to the importance of university-led technology transfer in Asia, key strategies and goals for technology transfer, and implementation approaches taken by each university to promote technology transfer from university to industry.
President Kang was invited to this GULF session, the only attendant from Korean universities, in recognition of his long time experience and expertise in education and research.
In 2006, WEF created the GULF, a small community of the presidents of top universities in the world, aiming to offer an open platform for high-level dialogues on issues of higher education and research with other sectors, as well as to foster collaboration between universities in areas of significance for global policy.
As of 2014, a total of 25 globally leading universities, including Harvard University, University of Cambridge, and Massachusetts Institute of Technology, are GULF members. KAIST, which joined the club this year, is the only Korean university.
The 2014 Annual Meeting of the New Champions, also known as the Summer Davos Forum, hosts numerous sessions under the theme of “Creating Value through Innovation.” At the Forum, a total of ten IdeasLab sessions will be hosted. KAIST was invited to run its own IdeasLab on nanotechnology on September 12, 2014.
Together with President Kang, Professors Sang Ouk Kim and Keon Jae Lee from the Department of Materials Science Engineering, KAIST, and Professors Sang Yup Lee and Hyunjoo Lee from the Department of Chemical and Biomolecular Engineering, KAIST, will present their own speeches on the topic entitled “From diagnostics to materials, how is nanotechnology changing lives?”
President Kang will give the opening speech at the KAIST IdeasLab.
He said that an invitation from WEF to join the IdeasLab spoke well for KAIST:
“KAIST is the first and the only Korean university ever invited to run its own IdeasLab at the World Economic Forum. The IdeasLab is an expert group meeting, conducted only by the world’s most prestigious universities and research institutes. At the IdeasLab sessions, global leaders from different sectors identify major issues facing higher education and humanity and explore solutions through science and technology innovation. Holding our own IdeasLab on one of our strongest fields, nanotechnology, is indeed an excellent opportunity for KAIST to show its strength in academic and research excellence on the global stage.”
2014.09.08 View 14531 -
KAIST's Advanced Biomass R&D Center and ToolGen will cooperate
The Advanced Biomass R&D Center (ABC) at KAIST and ToolGen, Inc., a Korean biotechnology company focused on the development of engineered nucleases that can be used as essential tools for editing genetic information in microbial, plant, animal, and human cells, signed a memorandum of understanding (MOU) on August 18, 2014 for technology exchange and research collaboration.
ABC is headed by Executive Director Ji-Won Yang, a professor emeritus at the Department of Chemical and Biomolecular Engineering, and Chief Executive Officer Jong-Moon Kim for ToolGen.
The newly signed MOU encourages collaborations in the following areas:
- Development of genome editing technology for microalgae modification
- Development of microalgae that increases biofuel production through the
application of genome editing technology
- Creation of education and training programs for researchers
- Collaboration in other areas
In addition, the two organizations decided to cooperate in the improvement of biofuel yields using ToolGen’s genome editing technology, the commercialization of research outcomes, and the development of eco-friendly biofuels from biomass.
Executive Director Yang commented that “improving biofuel production is crucial to accelerate the commercialization of biofuels, and collaborating with ToolGen will help us realize that goal.” He further said that “The importance of this MOU lies in the fact that the global chemical industry including Korea has been making substantial efforts to shift its attention from a fossil fuel-based development to a more bio-based technology.”
Jin-Soo Kim, the director of the Genome Editing Research Center at the Institute of Basic Sciences in Korea and the cofounder of ToolGen, added that “ToolGen has successfully commercialized its third generation genetic scissors, which shows a lot of promise for commercialization. Our collaboration with KAIST will serve as the driving force to create new industries and accordingly, new jobs.”
2014.09.03 View 10916