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Semiconductor Photonic Nanocavities on Paper Substrates
Professor Yong-Hoon Cho of the Department of Physics and his team at KAIST have developed a semiconductor photonic nanocavity laser that can operate on a paper substrate.
The researchers hope that this novel method, which involves transferring nano-sized photonic crystal particles onto a paper substrate with high absorptiveness, will enable the diagnoses of various diseases by using high-tech semiconductor sensors at low cost.
The results of this research were published in the November 17th, 2016, issue of Advanced Materials.
Photonic crystals, which utilize light as a medium to provide high bandwidths, can transfer large amounts of information. Compared with their electronic counterparts, photonic crystals also consume less energy to operate.
Normally, semiconductor photonic particles require substrates, which play only a passive role in the assembly and endurance of individual, functional photonic components. These substrates, however, are bulky and environmentally hazardous as they are made up of non-biodegradable materials.
The research team overcame these two shortcomings by replacing a semiconductor substrate with standard paper. The substrate’s mass was reduced considerably, and because paper is made from trees, it degrades. Paper can be easily and cheaply acquired from our surroundings, which drastically reduces the unit cost of semiconductors.
In addition, paper possesses superior mechanical characteristics. It is flexible and can be repeatedly folded and unfolded without being torn. These are traits that have long been sought by researchers for existing flexible substrates.
The research team used a micro-sized stamp to detach photonic crystal nanobeam cavities selectively from their original substrate and transfer them onto a new paper substrate. Using this technique, the team removed nanophotonic crystals that had been patterned (using a process of selectively etching circuits onto a substrate) onto a semiconductor substrate with a high degree of integration, and realigned them as desired on a paper substrate.
The nanophotonic crystals that the team combined with paper in this research were 0.5 micrometers in width, 6 micrometers in length, and 0.3 micrometers in height—about one-hundredth of the width of a single hair (0.1 millimeter).
The team also transferred their photonic crystals onto paper with a fluid channel, which proved that it could be used as a refractive index sensor. As can be seen in current commercial pregnancy diagnosis kits, paper has high absorptiveness. Since photonic crystal particles have high sensitivity, they are highly suitable for applications such as sensors.
Professor Cho stated that “by using paper substrates, this technology can greatly contribute to the rising field of producing environmentally-friendly photonic particles” and “by combining inexpensive paper and high-performance photonic crystal sensors, we can obtain low prices as well as designing appropriate technologies with high performance.”
Dr. Sejeong Kim of the Department of Physics participated in this study as the first author, and Professor Kwanwoo Shin of Sogang University and Professor Yong-Hee Lee of KAIST also took part in this research. The research was supported by the National Research Foundation’s Mid-Career Researcher Program, and the Climate Change Research Hub of KAIST.
Figure 1. Illustration of photonic crystal lasers on paper substrates
Figure 2. Photonic crystal resonator laser and refractive index sensor operating on paper substrates
2017.03.01 View 7029 -
Welcoming the 2017 Freshmen
President Sung-Chul Shin welcomed 756 new undergraduates for 2017 during the Freshmen Convocation on February 27, urging them to be adamant in challenging themselves to become global leaders during the next four years and beyond at KAIST. Family, friends, faculty, and staff members cheered them on at the ceremony in the auditorium. The KAIST orchestra and chorus also celebrated the freshmen’s new start.
President Shin encouraged students to become global leaders by deepening their knowledge of basic studies as well as broadening their interdisciplinary spectrum while studying at KAIST.
“In the era of Industry 4.0, new discoveries will be made in interdisciplinary studies. Thus, I ask you to study humanities and social studies very diligently, the basis of creative research and development to broaden your knowledge spectrum. Conventionally, the science and technology fields are dominated by left-sided brains working while the humanities and social sciences are influenced by the right brain. KAIST will soon provide a new curriculum of full-brain teaching which will actively stimulate both sides of the brain. Such a new track will help students fully exercise their ingenuity, especially in comprehending the newest trends of science and technology,” he said.
He added, “Korea stands as one of seven most innovative nations with significant growth potential and the world is paying attention to us. You are the top 0.3 percent of science and technology talents in the nation who will be the leaders of our future. Thus, we plan to establish the Global Leadership Center in order to train our students to be outstanding leaders through their qualifications, manner, and mindset.”
He also cited communication skills as a critical aspect that every student, especially those majoring in science and technology, should focus on. “Communication is a critical tool for any scientist and leader. Students should study and learn how to better present themselves and deliver what they think more effectively and persuasively to others in the hyper-connected, horizontal society of the future. In particular, English communication skills are very crucial for engaging in leadership roles on the global stage.”
Finally, President Shin asked students to manage their time well in order to accomplish their goals. “Your future will be determined by what dreams you dream in college and how you prepare for it. I hope that your days at KAIST will be a time of diligent preparation for your ambitious dreams,” he added.
For full context of his speech, please click.
(Photo caption: President Shin makes a welcoming address at the 2017 Freshmen Convocation (above) and freshmen representatives present the oath of freshmen to President Shin.)
2017.02.28 View 3519 -
Quantum Dot Film Can Withstand High Temperatures and Humidity
The joint KAIST research team of Professor Byeong-Soo Bae of the Department of Materials Science and Engineering and Professor Doh Chang Lee of the Department of Chemical and Biomolecular Engineering was able to fabricate a siloxane-encapsulated quantum dot film, which exhibits stable emission intensity over one month even at high temperatures and humidity.
The results of this study were published in the Journal of the American Chemical Society (JACS) on November 29, 2016. The research article is entitled “Quantum Dot/Siloxane Composite Film Exceptionally Stable against Oxidation under Heat and Moisture.” (DOI: 10.1021/jacs.6b10681)
Quantum dots (QDs), light-emitting diodes (LEDs) for next-generation displays, are tiny particles or nanocrystals of semiconducting materials. Their emission wavelength can easily be adjusted by changing their sizes, which are just a few nanometers. A wide spectrum of their colors can also achieve ultra-high definition displays.
Due to these characteristics, QDs are coated on a film as a polymer resin in dispersed form, or they are spread on an LED light source. They are thus considered to be crucial for next generation displays.
Despite their exceptional optical properties, however, QDs are easily oxidized in a high temperature and high humidity environment, and, as a result, this greatly deteriorates their luminescence quality (quantum efficiency). Therefore, they are encapsulated in an extra thin layer to block oxygen and moisture.
QD displays in the current market have a film inserted to separate them from LEDs, which create heat. The high unit cost of this protective layer, however, increases the overall cost of displays, lowering their price competitiveness in the market.
For a solution, the research team applied the sol-gel condensation reaction of silane precursors with QDs. This technology uses the reactions of chemical substances to synthesize ceramics or glass at a low temperature.
The team applied QDs in a heat resistant siloxane polymer by employing this technology. The siloxane resin acted as a cup holding the QDs and also blocked heat and moisture. Thus, their performance can be maintained without an extra protective film.
QDs are evenly dispersed into the resin from a chemical process to fabricate a QD embedded film and retained the high quality luminescence not only at a high temperature of 85°C and in a high humidity of 85%, but also in a high acid and high base environment. Remarkably though, the luminescence actually increased in the high humidity environment.
If this technology is used, the overall price of displays will decrease by producing a stable QD film without an extra protective barrier. In the future, the QD film can be directly applied to a blue LED light source. As a result, it will be possible to develop a QD display that can reduce the amount of QDs needed and improve its performance.
Professor Bae said, “We have proposed a way to make quantum dots overcome their limitations and have wide applications as they are being developed for next-generation displays. Our technology will make significant contributions to the display industry in the country.”
He also added, “In the future, we plan to cooperate with companies both in and out of the country to improve the performance of quantum dots and concentrate on their commercialization.”
The research team is currently applying for related patents both in and out of the country. The team is also plan ning to transfer the patents to Sol Ip Technology Inc., a company founded at KAIST, to start the commercialization.
Picture 1:
Siloxane-encapsulated quantum dot (QD) films showing performance stability in boiling water
Picture 2 and 3:
So-gel condensation reaction in silane precursors between Methacryloxypropyltrimethoxysilane (MPTS) and diphenylsilanediol (DPSD). The inset shows photographs of a QD-oligosiloxane resin under room light (left) and a UV lamp (λ = 365 nm) (right).
Free radical addition reactions among carbon double bonds of methacryl functional groups and oleic acids. The inset shows photographs of a QD-silox film under room light (left) and a UV lamp (λ = 365 nm) (right).
2017.02.24 View 9480 -
Prof. Woo Chang Kim Is Appointed as Managing Editor of Quantitative Finance
Professor Woo Chang Kim of the Industrial and Systems Engineering Department has been elected as the Managing Editor of Quantitative Finance.
Founded in 2001, Quantitative Finance has been an internationally-acclaimed peer-reviewed journal in the field of financial engineering, along with Mathematical Finance.
This is the first time for a Korean researcher to be named for the editorial board, which consists of eminent scholars from around the world, including four Nobel laureates.
Professor Kim’s expertise lies in financial optimization, portfolio management, and asset liability management. In recent years, he has focused his research on robo-advisors in the area of FinTech, and for this contribution, he was appointed as managing editor.
Professor Kim also served as an editor, deputy editor, and a member of the editorial boards for various journals, including the Journal of Portfolio Management and Optimization and Engineering. Currently, he serves as a member of the Korean National Pension Fund’s Electoral Commission, an adviser to Samsung Asset Management Co., Ltd., and the director of the KAIST Asset Management for Future Technology Research Center that was opened in October 2016.
2017.02.23 View 7406 -
A KAIST Alumnus Receives the Marie Sklodowska-Curie Individual Fellowships
Dr. Je-Kyung Ryu, a graduate of the Physics Department at KAIST in 2014, received the 2017 Marie Sklodowska-Curie Individual Fellowship.
Established in 1996, the Marie Sklodowska-Curie Individual Fellowships support young scientists in or outside Europe to help them grow as independent researchers. The recipients are recognized to have the highest potential to make a difference in science and technology and work on research and innovation.
Dr. Ryu is currently working as a postdoctoral researcher at the Cees Dekker Lab in the Department of Bionanoscience at the Kavli Institute of Nanoscience at Delft University of Technology (TU Delft), Netherlands.
He was among six international researchers at TU Delft who were awarded this research grant.
The grant of 177,000 euros will be offered for two years from March 2017 to February 2019 to cover his salary and research expenses.
For a news article published by TU Delft on the award, please click below:
QN and BN Successfully Attract Young Scientific Talent
February 1, 2017
2017.02.22 View 6221 -
Dr. Sung-Chul Shin Selected 16th President of KAIST
(President Sung-Chul Shin)
The KAIST Board of Trustees elected Professor Sung-Chul Shin of the Department of Physics the 16th president of KAIST on February 21. Professor Shin succeeds President Sung-Mo Kang whose four-year term will end on February 23. He is the first KAIST alumnus to serve as its president.
The Board of Trustees announced, “We believe that Professor Shin’s scientific achievement, outstanding leadership, and clear vision will serve KAIST faculty, students, and staff very well. He will be the best person to help KAIST leap forward in the four years ahead.”
The newly-elected president said, “I am humbled and honored to have been elected to lead such a prestigious institute of Korea. Aiming to be one of the top ten global universities, KAIST will continue to innovate its systems.” Previously, Dr. Shin led the Daegu Gyeongbuk Institute of Science and Technology (DGIST) for six years as president since 2011.
Professor Shin joined the KAIST faculty in 1989. He graduated from Seoul National University and then earned his MS degree in condensed matter physics at KAIST in 1977. After earning his Ph.D. in material physics at Northwestern University in 1984, he worked at Eastman Kodak Research Labs as a senior research scientist for five years.
Before heading to DGIST, President Shin held key administrative positions at KAIST from the early 1990s including dean of planning, dean of the international office, and vice-dean of student affairs. During President Robert Laughlin’s tenure, the first foreign president at KAIST, he served as vice-president for two years from 2004. He also served on the Presidential Advisory Council on Science and Technology of the Korean government as vice chairperson from 2015 to 2016.
A renowned scholar in the field of nanoscience, President Shin’s research focuses on the artificial synthesis and characterization of nonmagnetic materials, magnetic anisotropy, and magneto-optical phenomena. He leads the Laboratory for Nanospinics of Spintronic Materials at KAIST and has published in 290 journals while holding 37 patents.
A fellow in the American Physical Society (APS) since 2008, he was the president of the Korean Physical Society from 2011 to 2012. He has been on the editorial board of J. Magnetism and Magnetic Materials from 2009 and was the first Korean recipient of the Asian Union of Magnetics Societies (AUMS) Award, which recognizes outstanding scientists in the field of magnetics.
President Shin envisions making KAIST’s research and education more competitive through continuing innovation. His innovation efforts will extend to the five key areas of education, research, technology commercialization, globalization, and future planning.
Among his priorities, he emphasizes multidisciplinary studies and leadership training for students. He plans to focus on undeclared major courses for undergraduates to help them expand their experience and exposure to diverse disciplines. This approach will help create well-rounded engineers, scientists, and entrepreneurs by enabling them to develop skills while leveraging a strong connection to the arts, humanities, and social sciences.
To better respond to Industry 4.0, which calls for convergence studies and collaborative work, he proposed establishing a ‘Convergence Innovation System’ by strategically selecting 10 flagship convergence research groups. In order to accelerate the technology commercialization and ecosystem of start-ups, he will strengthen entrepreneurship education, making it a prerequisite requirement for students. President Shin said he will spare no effort to incubate and spin-off ventures in which KAIST technology is being transferred. For globalization efforts, he plans to increase the ratio of foreign faculty from 9 percent to 15 percent, while doubling the current foreign student enrollment ratio of 5 percent. For future strategic innovation, he will implement a long-term innovation strategic plan dubbed ‘Vision 2031.’
2017.02.22 View 9353 -
Controlling Turtle Motion with Human Thought
KAIST researchers have developed a technology that can remotely control an animal’s movement with human thought.
In the 2009 blockbuster “Avatar,” a human remotely controls the body of an alien. It does so by injecting human intelligence into a remotely located, biological body. Although still in the realm of science fiction, researchers are nevertheless developing so-called ‘brain-computer interfaces’ (BCIs) following recent advances in electronics and computing. These technologies can ‘read’ and use human thought to control machines, for example, humanoid robots.
New research has demonstrated the possibility of combining a BCI with a device that transmits information from a computer to a brain, or known as a ‘computer-to-brain interface’ (CBI). The combination of these devices could be used to establish a functional link between the brains of different species. Now, researchers from the Korea Advanced Institute of Science and Technology (KAIST) have developed a human-turtle interaction system in which a signal originating from a human brain can affect where a turtle moves.
Unlike previous research that has tried to control animal movement by applying invasive methods, most notably in insects, Professors Phill-Seung Lee of the Mechanical Engineering Department and Sungho Jo of the Computing School propose a conceptual system that can guide an animal’s moving path by controlling its instinctive escape behavior. They chose a turtle because of its cognitive abilities as well as its ability to distinguish different wavelengths of light. Specifically, turtles can recognize a white light source as an open space and so move toward it. They also show specific avoidance behavior to things that might obstruct their view. Turtles also move toward and away from obstacles in their environment in a predictable manner. It was this instinctive, predictable behavior that the researchers induced using the BCI.
The entire human-turtle setup is as follows: A head-mounted display (HMD) is combined with a BCI to immerse the human user in the turtle’s environment. The human operator wears the BCI-HMD system, while the turtle has a 'cyborg system'—consisting of a camera, Wi-Fi transceiver, computer control module, and battery—all mounted on the turtle’s upper shell. Also included on the turtle’s shell is a black semi-cylinder with a slit, which forms the ‘stimulation device.’ This can be turned ±36 degrees via the BCI.
The entire process works like this: the human operator receives images from the camera mounted on the turtle. These real-time video images allow the human operator to decide where the turtle should move. The human provides thought commands that are recognized by the wearable BCI system as electroencephalography (EEG) signals. The BCI can distinguish between three mental states: left, right, and idle. The left and right commands activate the turtle’s stimulation device via Wi-Fi, turning it so that it obstructs the turtle’s view. This invokes its natural instinct to move toward light and change its direction. Finally, the human acquires updated visual feedback from the camera mounted on the shell and in this way continues to remotely navigate the turtle’s trajectory.
The research demonstrates that the animal guiding scheme via BCI can be used in a variety of environments with turtles moving indoors and outdoors on many different surfaces, like gravel and grass, and tackling a range of obstacles, such as shallow water and trees. This technology could be developed to integrate positioning systems and improved augmented and virtual reality techniques, enabling various applications, including devices for military reconnaissance and surveillance.
***
Reference: “Remote Navigation of Turtle by Controlling Instinct Behavior via Human Brain-computer Interface,” Journal of Bionic Engineering, July 2016 (DOI: 10.1016/S1672-6529(16)60322-0)
Depiction of Cyborg System
A human controller influences the turtle’s escape behavior by sending left and right signals via Wi-Fi to a control system on the back of the turtle.
2017.02.21 View 13799 -
The 2016 Research Highlights
KAIST has selected the ten most outstanding projects of 2016 conducted by its faculty and researchers. This selection embodies the KAIST research portfolios that translate their discoveries into meaningful and measurable impact toward a better world. All of them demonstrate exceptional creativity, which open new research paths for each field in its novelty, innovation, and impact.
The following list has been reviewed by a committee of faculty peers headed by Associate Vice President for Research. Following are the 2016 KAIST research highlights:
□ Commercialization of 3D Holographic Microscopy
By YongKeun Park of the Department of Physics
Professor YongKeun Park and his colleagues develop a powerful technique to measure 3D images of live cells without labeling agents. This technique, called 3D holographic microscopy or holotomography, will open a new avenue for the study of cell biology and its applications in medical diagnosis. This research also led to the founding of a start-up company Tomocube Inc. and the successful commercialization of the technique.
Professor Park and his research team developed a solution based on digital holography technology used to visualize 3D refractive index tomograms of live cells without staining. This allowed the real-time observation of biological cells in 2D, 3D, and 4D without the use of labeling agents. Conventional techniques for 3D cell imaging requires the use of labeling agents such as fluorescence dyes and proteins, which prevent from investigating the physiology of intact untreated cells. In particular, label-free imaging capability becomes more important in several emerging fields such as stem cell research and immunotherapy.
The team employs the concept of 3D digital holography to achieve the optical measurements of 3D refractive index tomograms of live cells and tissues. Also, a digital micromirror device (DMD), which has been used for DLPTM projectors, was utilized to steer a laser beam for 3D measurements.
Tomocube, founded from seed money funded by the EndRun Project of the Institute for Startup KAIST, succeeded in the commercialization of the 3D holographic microscopy and established an international distribution network in more than ten countries. It now has started exporting the product to several countries. The microscopes are being used in several leading research institutes including MIT, German Cancer Center, Pittsburg Medical Center, and Seoul National University Hospital Selected as one of the top ten mechanical technologies of 2016 by the Korean Society of Mechanical Engineers, the team raised four billion KRW investment from industry leaders including Soft Bank Venture Korea, Hanmi Pharmaceutical, and InterVest investment.
(Figure: Images of cells measured by 3D microscopy)
□ Designer Proteins with Chemical Modifications
By Hee-Sung Park and Hee Yoon Lee of the Department of Chemistry
Professor Hee-Sung Park developed a new strategy for installing authentic post-translational modifications (PTM) into recombinant proteins. Most essential biological processes are controlled by PTM, which plays a critical role in metabolic changes. However, abnormal protein modification aroused by environmental or genetic factors induce diverse diseases such as neurodegenerative diseases, cancer, and many other chronic diseases.
Professor Park has conceived a novel chemical biology route to achieve authentic and selective chemical modifications in proteins.He first used the established O-phosphoserine (Sep) orthogonal translational system to create a Sep-containing protein. The Sep residue is then dephosphorylated to dehydroalanine (Dha). Finally, Zn-Cu is conjugated to Dha of alkyl iodides, which enables it to form chemo-selective carbon-carbon bonds.
This approach offers a powerful tool to engineer designer proteins with diverse chemical modifications, providing a novel platform for investigating numerous diseases and drug development including for cancer and Alzheimer's. Furthermore, this research will allow mass production of abnormally modified proteins that could induce diseases, opening up new prospects in disease treatment research. It will help to enable investigation and discovery of new drug inhibitors that directly target abnormally modified proteins.
(Figure: Application of Customized Protein Modification Technology)
□ Lanthanum-Catalyzed Synthesis of Microporous 3D Graphene-Like Carbons in a Zeolite Template
By Ryong Ryoo, of the Department of Chemistry
Professor Ryong Ryoo’s team presented a scaled-up carbon synthesis viable for practical applications such as Li-ion batteries and catalyst supports.
Zeolite-templated carbon has an extremely large surface area and a regular microporous structure. As a result, it was expected to show excellent performance in various applications, such as for electrode materials or catalyst supports. However, until recently difficulties in synthesis have hindered research on application and properties of zeolited-templated carbon compared to other porous carbon materials.
Professor Ryoo’s team demonstrated that lanthanum ions embedded in zeolite pores lowered the temperature for carbonization of ethylene or acetylene. In this contribution, a graphene-like carbon structure was selectively formed inside zeolite template without the non-selective carbon deposition. Single crystal X-ray diffraction data revealed that carbon formed along the micropore surface. After removal of zeolite template, the carbon framework showed high electrical conductivity.
His synthesis method not only allowed selectivity in ethylene carbonization inside zeolite pore but permitted the diffusion of carbon material even when a large amount of zeolites was synthesized at once, allowing mass production of carbon. Thus, this method is expected to accelerate research on the application and properties of zeolite-templated carbon.
(Figure: Electron density distribution of zeolite that underwent selective pore carbonization. The structure of carbon determined by electron density distributions of carbon atoms, shown in yellow and red, within the framework of zeolite, shown in blue, can be observed.)
□ Complete Prevention of Blood Loss by Self-Sealing Hemostatic Needles
By Haeshin Lee of the Department of Chemistry
Professor Haeshin Lee’s team invented a hemostatic hypodermic needle, which prevented bleeding of punctured tissue during and after injections.
Bleeding unavoidably accompanies injections when a conventional needle penetrates tissue. Though the scale of bleeding from controlled injections does not cause harm to healthy individuals, uncontrolled bleeding may bring serious complications for those who suffer from hemophilia, coagulopathy, or who have been exposed to infectious diseases.
Professor Lee’s hemostatic hypodermic needle is coated with partially cross-linked catechol-functionalized chitosan that undergoes a solid-to-gel phase transition in situ to seal-seal punctured tissues. The team reported a complete prevention of blood loss following intravenous and intramuscular injections in animal models. They observed a 100% survival rate in hemophiliac mice following a syringe injection into a jugular vein.
The self-sealing hemostatic needles may help to prevent complications associated with bleeding in clinical settings such as for diabetic patients who experience delayed hemostasis and in the procedure of biopsy thereby preventing profuse bleeding.
□ An Immunological Mechanism for the Contribution of Commensal Microbiota Against Herpes Simplex Virus Infection in Genital Mucosa
By Heung Kyu Lee of the Graduate School of Medical Science and Engineering
Professor Heung Kyu Lee identified an immunological mechanism of commensal microbiota against herpes virus infections. The protective mechanisms of commensal bacteria against viral infections was limited to how immune inductive signals are provided by commensal bacteria for enhancing innate and adaptive immunity. Until Professor Lee’s research discovery, whether, or how, commensal bacteria might influence the effector arm of immune responses such as effector T cells to eliminate infected virus remained unknown.
Professor Lee’s team demonstrated that dysbiosis within the vaginal microbiota resulted in severe impairment of antiviral protection against HSV-2 infection. IL-33 released into the vaginal tract after antibiotic treatment blocked the ability of effector T cells to migrate into vaginal tissues and secrete the antiviral cytokine, IFN-γ. Thus, the findings suggested a previously unstudied role of commensal bacteria in the effector phase of the antiviral immune response against genital herpes. These findings provided insight into the mechanisms by which the secretion of proteases from opportunistic pathogens in susceptibility to various sexually transmitted pathogens might induce type 2 immunity within the female genital tract.
Promoting awareness of overuse of antibiotics, the research is expected to contribute to the development of viral vaccines with enhanced defense capacity by regulating commensal bacteria to promote health.
□ Development of a Pulse-Echo Laser Ultrasonic Propagation Imaging System
By Jung-Ryul Lee of the Department of Aerospace Engineering
Professor Jung-Ryul Lee’s team for the first time developed a mobile laser ultrasonic propagation imaging system that is capable of 2500-point inspection per second and visualization of pulse-echo ultrasonic wave through the thickness of a solid medium. This novel ultrasonic propagation visualization system has been successfully prototyped for the application of in-situ and in-process nondestructive evaluation of aerospace structures.
The real world proof-of-concept was achieved by testing the new system in the inspection of a space launcher fuselage (KSLV-II), control surfaces of military transport (CN-235), and the brake disk of F-16, guided weapon fuselage. In addition, the system has passed F-16 standard specimen test done by Korea Air Force and got a US patent. The prototype which was developed over a period of two years has been successfully delivered to Korea Air Force last December.
Furthermore, Boeing has expressed interest in prototype development project and KAIST OESL has been selected as the Boeing-KAIST technical contact lab and received a two-year grant from Boeing. The second prototype is under construction for Boeing and the third prototype will be delivered to an optional research institute and used as a standard inspection instrument.
□ Birefractive Stereo Imaging for Single-Shot Depth Acquisition
By Min H. Kim of the School of Computing
Professor Min H. Kim’s team proposed a novel 3D imaging method that allows the capture of not only color pictures but also corresponding depth images while traditional cameras capture just color pictures.
Depending on the polarization state of light, the incident light on a birefringent material such as calcite can be refracted into two different angles. This physical phenomenon is called double refraction. Whereas traditional stereo imaging requires at least two stereo cameras, 3D imaging method can capture depth from a single picture of double refraction. This proposed 3D imaging technique can be applied to many graphics and computer vision applications such as AR/VR applications that require color and depth information simultaneously.
This technology, which could measure depth images, is currently needed for various industrial applications. The suggested method in this research to measure depth information from one photo using double refraction media accurately can be used in areas where system size and cost are important, such as mobile cameras, VR/ARs, driverless cars, and 3D microscopes.
(Figure: Measuring high-resolution depth of single image via bi-refringent medium)
□Development of Environment Friendly Geotechnical Construction Material Using Biopolymer
By Gye-Chun Cho of the Department of Civil and Environmental Engineering
Professor Gye-Chun Cho has succeeded in making a 100% bio-based KABS (KAIST Bio-Soil) binder using biopolymer, an eco-friendly geotechnical construction material. A biopolymer is an organic polymer produced in the course of microbial activities and thus is an eco-friendly material manufactured without generating carbon dioxide. Biopolymers have been used in food, agriculture, cosmetics, and medicine as hardener and gelling agents, but have never been applied in construction. His team verified the microscopic interaction, feasibility, and strengthening mechanism of microbial biopolymers for soils for the first time in the world, suggesting that biopolymers be an eco-friendly soil binder.
In addition to soil binders, biopolymers can also be applied to various fields of ground construction (e.g., ground improvement, grouting, erosion control, vegetation, anti-desertification, etc.). The team expects more biopolymer applications in construction since increasing demands for replacing cement-based or chemical ground materials have surged.
With KABS binder, the team has performed several field tests along with industrial technology transfer underway. In collaboration with the Korea Expressway Corporation and LH Corporation, Professor Cho’s team is working on additional commercial applications.
(Figure: Strength enhancement effect of soil grain processed by biopolymer )
□ Protein Delivery Via Engineered Exosomes
By Chulhee Choi of the Department of Bio and Brain Engineering
Professor Chulhee Choi’s team unveiled a new tool for intracellular delivery of target proteins, named “exosomes for protein loading via optically reversible protein-protein interactions” or “EXPLORs”.
Nanoparticle-mediated delivery of functional macromolecules is a promising method for treating a variety of human diseases. Among nanoparticles, cell-derived exosomes have recently gained attention as a new therapeutic strategy for the in vivo delivery of nucleotides and chemical drugs.
By integrating a reversible protein-protein interaction module controlled by blue light with the endogenous process of exosome biogenesis, the team successfully loaded cargo proteins into newly generated exosomes. Treatment with protein-loaded EXPLORs is shown to significantly increase intracellular levels of cargo proteins and their function in recipient cells in vitro and in vivo.
These results clearly indicate the potential of EXPLORs as a mechanism for the efficient intracellular transfer of protein-based therapeutics into recipient cells and tissues. This technology has been transferred to KAIST bio-venture Cellex Life Science, Incorporated for commercialization.
□ Hot Electron Detection under Catalytic Reactions
By Jeong Young Park of the Graduate School of EEWS
Professor Jeong Young Park’s team developed a novel catalytic nanodiode consisting of a thin metal catalyst deposited onto a semiconductor support. The team succeeded in observing in real-time hot electrons created in the course of catalytic reaction occurring at atmospheric pressure or at liquid-solid interfaces.
Use of a noble catalytic nanodiode is a new measurement system that detects hot electrons produced on catalyst surface through atmospheric pressure and liquid chemical reaction in real time that allows direct identification of the catalytic activity of catalytic reactions. In particular, the system allows macro-observation of hot-electron movements that change with the type of nano-catalyst without high-priced equipment in atmospheric pressure and liquidation, and thus is not limited to experimental conditions such as in ultrahigh vacuums.
Therefore, it could be applied in the future to analyze complex chemical reaction mechanisms of catalysts used in high temperature and various pressure conditions, and to develop high efficiency next-generation catalyst materials. This finding may lead not only to the fundamental understanding in the mechanism of the catalytic reactions but also to the development of next-generation catalysts with enhanced catalytic performance.
(Figure: Schematic diagrams of nano-catalyst hot electron element and graphene hot electron detector)
2017.02.20 View 13140 -
Professor Hahn Named Sangnam Business Researcher Awardee
Professor Minhi Hahn of the School of Management Engineering at the KAIST College of Business has been named the winner of the 22nd Sangnam Business Researcher Award. The Sangnam Award is the highest distinction made by the Korean Academic Society of Business Administration to recognize an outstanding scholar in the field of business & management for that year.
His research focuses on how marketing communication impacts customer choices and their satisfaction. Professor Hahn has served on the faculty of the College of Business since 1989, and has supervised more than 21 Ph.D.s and 203 master’s students while publishing more than 51 papers in domestic and foreign journals. He served as dean of the KAIST College of Business, president of the Korean Marketing Association, and president of the Korean Society of Consumer Studies. Currently Professor Hahn is a board member on the strategic committee of the College of Management at National Sun Yat-sen University in Taiwan.
Professor Hahn said, “I am pleased to receive this award on behalf of the people who are working for the development of Korean business administration. I will do my utmost to support younger scholars to continue their meaningful research." The award ceremony will take place at the Plaza Hotel in Seoul on February 23.
2017.02.19 View 6238 -
Professor Shin Honored Posthumously for Iridescent Microparticles
(The Late Professor Joong-Hoon Shin (left) and Professor Shin-Hyun Kim)
A research team co-led by Professor Shin-Hyun Kim from the Department of Chemical and Biomolecular Engineering and Professor Jong-Ryul Jeong from the Department of Materials Science and Engineering at Chungnam National University developed iridescent microparticles with a structural color gradient. The research team posthumously dedicated their research to a renowned professor in the field of nanophotonics, the late Professor Joong-Hoon Shin of the Graduate School of Nanoscience and Technology at KAIST. He passed away suddenly in a car accident last September.
The iridescent microparticles, which allow on-demand control over structural color, will be key components for next-generation reflection-mode displays with clear color realization even in direct sunlight.
Materials such as opals, Morpho butterfly wings, and peacock feathers all display beautiful colors without pigment, using regularly-spaced nanostructures. Regularly-spaced nanostructures render color, by selectively reflecting the light of a particular wave through light interference. As such, materials that possess periodic modulation of refractive index at subwavelength scale are referred to as photonic crystals.
In general, photonic crystals are only able to display a single color, so limitations exist when attempting to apply them to reflection-mode displays which call for multiple structural colors. The research team addressed the issue using inspiration from snowflakes stacking in the winter. When snow falls on the surface of a round-shaped structure, the thickness of the snow stacking differs depending on the orientation. Based on this observation, the research team created photonic microparticles with a structural color gradient by depositing two different materials on spherical microparticles.
When some material is deposited on the surface of a sphere, the material on the top is thickest and becomes thinner on the sides. The team alternately deposited titania and silica on the spherical microparticles to form periodic modulation of the refractive index. The thickness of the alternating photonic layers is reduced along the angle from the top, which yields a structural color gradient.
Consequently, the microparticles reflect long-wavelength red light from the top of the sphere and short-wavelength blue light from the side of the sphere. Any color of the visible spectrum can be selected in between the top and side depending on the orientation of the microparticles.
The research team used an external magnetic field as a way to control the orientation of the photonic microparticles and the structural colors. As magnetic iron layer was deposited underneath the alternating photonic layer, it was possible to freely control the orientation of the microparticles using a magnet, thereby allowing control of the color seen by the users.
KAIST doctoral candidate Seung Yeol Lee of the Department of Chemical and Biomolecular Engineering is the first author of this research, with support from the Midcareer Researcher Program of the National Research Foundation and funded by the Ministry of Science, ICT, and Future Planning (MSIP). This research was published in the online edition of Advanced Materials on February 6, 2017.
Figure1: Sets of an OM image of photonic Janus microspheres and an SEM image showing a cross-section of the photonic layers.
Figure 2: A series of schematics and OM images showing the color change depending on the orientation angle of the photonic Janus microsphere.
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KAIST Celebrates the 2017 Commencement
KAIST hosted its 2017 Commencement, awarding diplomas to 2,767 members of the Class of 2017 during a ceremony on February 17. President Sung-Mo Kang, Minister Yang-hee Choi of Science, ICT, and Future Planning, and Chairman of the KAIST Board of Trustees Jang-Moo Lee joined the ceremony along with the graduates and their family and friends at the Ryu Keun Chul Sports Complex.
The graduating class included 638 Ph.D. degrees, 1,335 Master’s degrees, and 794 Bachelor’s degrees being conferred. Among them, Young-Ki Song from the Department of Electric Engineering was honored to win the Minister’s Award, the highest award bestowed to an undergraduate. The KAIST Presidential Award went to Min-Jae Park of the Department of Mathematical Sciences and the KAIST Board of Trustee Chairman’s Award was presented to Jae-Hyung Cho from the Department of Mechanical Engineering.
Including this year’s graduating class, KAIST has turned out more than 59,000 highly educated science and technology talents including 11,731 Ph.D.s since its foundation in 1971. This year, 24-year-old Seo-Hee Oh earned her Ph.D. in chemistry as the youngest Ph.D. of the year after completing her Master’s and Ph.D. combined course in three years.
President Sung-Mo Kang praised the creativity of this graduating class and their excellent ability in his charge, saying, “As future leaders of our society, you are expected to develop a sense of compassion and outstanding professionalism to contribute to the advancement of not only Korea but also the whole world.’
For full text of President Kang’s charge to the graduates, please click.
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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
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