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Hierarchical Porous Titanium Nitride Synthesized by Multiscale Phase Separation for LSBs
(from left: Professor Jinwoo Lee and PhD candidate Won-Gwang Lim)
A KAIST research team developed ultra-stable, high-rate lithium-sulfur batteries (LSBs) by using hierarchical porous titanium nitride as a sulfur host, and achieved superior cycle stability and high rate performance for LSBs.
The control of large amounts of energy is required for use in an electric vehicle or smart grid system. In this sense, the development of next-generation secondary batteries is in high demand. Theoretically, LSBs have an energy density seven times higher than commercial lithium ion batteries (LIBs). Also, their production cost can be reduced dramatically since sulfur can be obtained at a low price.
Despite these positive aspects, there have been several issues impeding the commercialization of LSBs, such as the low electric conductivity of sulfur, the dissolution of active materials during operation, and sluggish conversion reactions. These issues decrease the cycle stability and rate capability of batteries.
To tackle those issues, Professor Jinwoo Lee from the Department of Chemical and Biomolecular Engineering and his team synthesized a well-developed hierarchical macro/mesoporous titanium nitride as a host material for sulfur. The titanium nitride has a high chemical affinity for sulfur and high electrical conductivity. As a result, it prevents the dissolution of active materials and facilitates the charge transfer. Moreover, the synergistic effect of macropore and mesopore structures allows the stable accommodation of large amounts of sulfur and facilitates the electrolyte penetration.
Previously reported polar inorganic materials have a high affinity for sulfur, but it was challenging to control the porous architecture suitable to the sulfur host. This work breaks such limitations by developing a synthetic route to easily control the porous architecture of inorganic materials, which led to obtaining superior cycle stability and high rate capabilities.
Professor Lee said, “Some problems still remain in commercializing LSBs as next-generation batteries. Hence, there should be a continued research on this matter to solve the issues. Through this research, we secured a key technology for ultrastable, high-rate LSBs.”
This research was led by PhD candidate Won-Gwang Lim and collaborated on by Jeong Woo Han from POSTECH. It was chosen as the cover article of Advanced Materials on January 15, 2019.
Figure 1. Schematic illustration for the synthetic route of co-continuous h-TiN
Figure 2. The hierarchical multiscale porous structure is still retained without any collapse after the conversion to h-TiN. The good retention of the porous structure is attributed to the thick pore wall of the h-TiO₂derived from the block copolymer self-assembly
Figure 3. The cover page of Advanced Materials
2019.01.28 View 6263 -
First Korean Member of OceanObs' Organizing Committee
Professor Sung Yong Kim from the Department of Mechanical Engineering became the first Korean to be elected as an organizing committee member of the international conference OceanObs’19’, specializing in the ocean observing field.
Professor Kim has been actively engaged in advisory panels, technical committees, and working groups for the North Pacific Marine Science Organization (PICES). Through numerous activities, he was recognized for his professionalism and academic achievements, which led him to be appointed as a member of the organizing committee.
The organizing committee is comprised of leading scholars and researchers from 20 countries, and Professor Kim will be the first Korean scientist to participate on the committee.
Since 1999, the conference has been held every decade. Global experts specializing in oceanic observation gather to discuss research directions for the next ten years by monitoring physical, biological, and chemical variables in regional, national, and global oceans and applying marine engineering.
This year, approximately 20 institutes including NASA’s Jet Propulsion Laboratory (JPL), the National Science Foundation, the National Oceanic and Atmospheric Administration, and the European Space Agency will support funds as well as high-tech equipment to the conference.
This year’s conference theme is the governance of global ocean observing systems such as underwater gliders, unmanned vehicles, remote sensing, and observatories. The conference will hold discussions on monitoring technology and information systems to ensure human safety as well as to develop and preserve food resources. Additionally, participants will explore ways to expand observational infrastructures and carry out multidisciplinary approaches.
There will also be collaborations with the Global Ocean Observing System (GOOS) and the Partnership for Observation of the Global Oceans (POGO) to organize ocean observing programs and discuss priorities.
Finally, they will set a long-term plan for solving major scientific issues, such as climate change, ocean acidification, energy, and marine pollution.
Professor Kim said, “Based on the outcomes drawn from the conference, I will carry out research on natural disasters and climate change monitoring by using unmanned observing systems. I will also encourage more multidisciplinary research in this field.”
2019.01.25 View 9028 -
A Novel Material for Transparent and Flexible Displays
(Research team led by Professor Sang Youl Kim from the Department of Chemistry)
The next generation of flexible and transparent displays will require a high-performing and flexible polymeric material that has the optical and thermal properties of glass. The material must be transparent to visible light and have a low coefficient of thermal expansion (CTE). Unfortunately, such a polymeric material has not been available. A KAIST research team has succeeded in making a new polymeric material with an exceptionally low CTE value while retaining high transparency and excellent thermal and mechanical properties. The method developed for amorphous polymers with a controlled CTE can be applied to control the thermal expansion of organic materials as well.
Most of objects expands upon heating and shrinks by cooling, and organic polymers have a relatively large CTE compared to that of ceramics or metals. Thin, light-weight planar substrates for semiconductor devices should have a similar CTE of ceramics. Otherwise, the device can be cracked due to the stress caused by thermal expansion and contraction. Therefore, matching the CTE of the semiconductor device and the substrate is crucial for successful manufacturing of display devices. Forming a network structure by connecting polymer chains is a well-known method of reducing the CTE of amorphous polymers. However, polymers with a network structure eventually lose their flexibility and becomes brittle.
As an alternative method, Professor Sang Youl Kim from the Department of Chemistry and his team chose to adjust the distance and interaction between polymer chains. Thermal expansion and contraction of polymer films can be minimized by introducing interaction forces between the polymer chains and by arranging the direction of the force perpendicularly. The team successfully implemented this approach by appropriately designing the chemical structure of a transparent polymeric material. It is called poly (amide-imide) film, which is a transparent, flexible, and high-performing polymeric material. It is thermally stable enough to be used in the AMOLED (active-matrix organic light-emitting diode) fabrication process (stable at >400℃) with a low CTE (4ppm/℃).
The team made IGZO TFT (Indium Gallium Zinc Oxide Thin Film Transistor) devices on the newly synthesized transparent poly(amide-imide) film, and confirmed that the device could indeed operate normally even when it is folded down to a radius of 1mm.
Professor Kim said, “Our results suggest a way of controlling the thermal expansion of amorphous polymers similar to a level of glass without chemical cross-linking, which has long been regarded as a challenging problem. At the same time, we succeeded in making the polymer transparent and flexible. We expect that it can be applied to controlling the thermal expansion of various organic materials.”
This research, led by researchers Sun Dal Kim and Byungyoung Lee, was published in Science Advances on October 26. (DOI: 10.1126/sciadv.aau1956v)
2019.01.24 View 5536 -
New Members of KAST and Y-KAST 2019
(Professor Eui-Cheol Shin from the Graduate School of Medical Science and Engineering)
Professor Eui-Cheol Shin from the Graduate School of Medical Science and Engineering became a new fellow of the Korean Academy of Science and Technology (KAST) along with 25 other scientists in Korea. He is one of the top virus immunologists in Korea and has published a review article in Nature Reviews Immunology.
Meanwhile KAST selected and announced 26 young scientists under the age 43 who have shown great potential and the creativity to carry out next-generation research. The list of Y-KAST (Young Korean Academy of Science and Technology) includes six KAIST professors: Professor Ji Oon Lee from the Department of Mathematical Sciences, Professor Mi Hee Lim from the Department of Chemistry, Professor Shin-Hyun Kim from the Department of Chemical and Biomolecular Engineering, Professor Jung-Ryul Lee from the Department of Aerospace Engineering, Professor Hyunjoo Jenny Lee from the School of Electrical Engineering, and Professor Yeon Sik Jung from the Department of Materials Science and Engineering.
KAST conferred their fellowships and Y-KAST membership during the New Year Reception.
2019.01.22 View 7570 -
Noninvasive Light-Sensitive Recombinase for Deep Brain Genetic Manipulation
A KAIST team presented a noninvasive light-sensitive photoactivatable recombinase suitable for genetic manipulation in vivo. The highly light-sensitive property of photoactivatable Flp recombinase will be ideal for controlling genetic manipulation in deep mouse brain regions by illumination with a noninvasive light-emitting diode. This easy-to-use optogenetic module made by Professor Won Do Heo and his team will provide a side-effect free and expandable genetic manipulation tool for neuroscience research.
Spatiotemporal control of gene expression has been acclaimed as a valuable strategy for identifying functions of genes with complex neural circuits. Studies of complex brain functions require highly sophisticated and robust technologies that enable specific labeling and rapid genetic modification in live animals. A number of approaches for controlling the activity of proteins or expression of genes in a spatiotemporal manner using light, small molecules, hormones, and peptides have been developed for manipulating intact circuits or functions.
Among them, recombination-employing, chemically inducible systems are the most commonly used in vivo gene-modification systems. Other approaches include selective or conditional Cre-activation systems within subsets of green fluorescent protein-expressing cells or dual-promoter-driven intersectional populations of cells.
However, these methods are limited by the considerable time and effort required to establish knock-in mouse lines and by constraints on spatiotemporal control, which relies on a limited set of available genetic promoters and transgenic mouse resources.
Beyond these constraints, optogenetic approaches allow the activity of genetically defined neurons in the mouse brain to be controlled with high spatiotemporal resolution. However, an optogenetic module for gene-manipulation capable of revealing the spatiotemporal functions of specific target genes in the mouse brain has remained a challenge.
In the study published at Nature Communication on Jan. 18, the team featured photoactivatable Flp recombinase by searching out split sites of Flp recombinase that were not previously identified, being capable of reconstitution to be active. The team validated the highly light-sensitive, efficient performance of photoactivatable Flp recombinase through precise light targeting by showing transgene expression within anatomically confined mouse brain regions.
The concept of local genetic labeling presented here suggests a new approach for genetically identifying subpopulations of cells defined by the spatial and temporal characteristics of light delivery. To date, an optogenetic module for gene-manipulation capable of revealing spatiotemporal functions of specific target genes in the mouse brain has remained out of reach and no such light-inducible Flp system has been developed. Accordingly, the team sought to develop a photoactivatable Flp recombinase that takes full advantage of the high spatiotemporal control offered by light stimulation.
This activation through noninvasive light illumination deep inside the brain is advantageous in that it avoids chemical or optic fiber implantation-mediated side effects, such as off-target cytotoxicity or physical lesions that might influence animal physiology or behaviors. The technique provides expandable utilities for transgene expression systems upon Flp recombinase activity in vivo, by designing a viral vector for minimal leaky expression influenced by viral nascent promoters.
The team demonstrated the utility of PA-Flp as a noninvasive in vivo optogenetic manipulation tool for use in the mouse brain, even applicable for deep brain structures as it can reach the hippocampus or medial septum using external LED light illumination.
The study is the result of five years of research by Professor Heo, who has led the bio-imaging and optogenetics fields by developing his own bio-imaging and optogenetics technologies. “It will be a great advantage to control specific gene expression desired by LEDs with little physical and chemical stimulation that can affect the physiological phenomenon in living animals,” he explained.
2019.01.22 View 6129 -
Enhanced Video Quality despite Poor Network Conditions
(from left: Jaehong Kim, Youngmok Jung, Hyunho Yeo, Professor Dongsu Han and Professor Jinwoo Shin)
Professor Jinwoo Shin and Professor Dongsu Han from the School of Electrical Engineering developed neural adaptive content-aware internet video delivery. This technology is a novel method that combines adaptive streaming over HTTP, the video transmission system adopted by YouTube and Netflix, with a deep learning model.
This technology is expected to create an internet environment where users can enjoy watching 4K and AV/VR videos with high-quality and high-definition (HD) videos even with weak internet connections.
Thanks to video streaming services, internet video has experienced remarkable growth; nevertheless, users often suffer from low video quality due to unfavorable network conditions. Currently, existing adaptive streaming systems adjust the quality of the video in real time, accommodating the continuously changing internet bandwidth. Various algorithms are being researched for adaptive streaming systems, but there is an inherent limitation; that is, high-quality videos cannot be streamed in poor network environments regardless of which algorithm is used.
By incorporating super-resolution in adaptive streaming, the team overcame the limit of existing content distribution networks, of which their quality relies too much on the bandwidth. In the conventional method, the server that provides the video splits a video into certain lengths of time in advance. But the novel system introduced by the team allows the downloading of neural network segments. To facilitate this method, the video server needs to provide deep neural networks for each video segment as well as sizes of Deep Neural Networks (DNN) according to the specifications of the user’s computing capacity.
The largest neural network size is two megabytes, which is considerably smaller than video. When downloading the neural network from the user’s video player, it is split into several segments. Even its partial download is sufficient for a slightly comprised super-resolution.
While playing the video, the system converts the low quality video to a high-quality version by employing super-resolution based on deep convolution neural networks (CNN). The entire process is done in real time, and users can enjoy the high-definition video.
Even with a 17% smaller bandwidth, the system can provide the Quality of Experience equivalent to the latest adaptive streaming service. At a given internet bandwidth, it can provide 43% higher average QoE than the latest service.
Using a deep learning method allows this system to achieve a higher level of compression than the existing video compression methods. Their technology was recognized as a next-generation internet video system that applies super-resolution based on a deep convolution neural network to online videos.
Professor Han said, “So far, it has only been implemented on desktops, but we will further develop applications that work in mobile devices as well. This technology has been applied to the same video transmission systems used by streaming channels such as YouTube and Netflix, and thus shows good signs for practicability.”
This research, led by Hyunho Yeo, Youngmok Jung and Jaehong Kim, was presented at the 13th UNSENIX OSDI conference on October 10 2018 and completed for filing international patent application.
For further information, please click here.
Figure 1. Image quality before (left) and after (right) the technology application
Figure 2. The technology Concept
Figure 3. A transition from low-quality to high quality video after video transmission from the video server
2019.01.22 View 6122 -
Main Cast Member of Drama KAIST Returns as KAIST Ambassador
(KAIST New Year Alumni Reception)
KAIST appointed Korean actor Min-woo Lee as KAIST Ambassador during the New Year Alumni Reception held on January 19.
Lee was one of the main characters in a popular Korean drama named KAIST, which aired from 1999 to 2000. It drew on a campus story of the top brains at KAIST and he was casted as a student studying electrical engineering. Along with the drama, he was recognized for building the positive image of KAIST.
As KAIST Ambassador, Lee will play various roles involved the promotion of Korea’s science and technology. For one year, he will be participating in major events and giving lectures to students.
Lee said that he still has strong affection for this drama. He added, “It is my great honor to be appointed as KAIST Ambassador and I will do my best to promote KAIST, the global value-creative leading university.”
(From left: Min-woo Lee and KAIST President Sung-Chul Shin)
2019.01.21 View 2829 -
A Comprehensive Metabolic Map for Bio-Based Chemicals Production
A KAIST research team completed a metabolic map that charts all available strategies and pathways of chemical reactions that lead to the production of various industrial bio-based chemicals.
The team was led by Distinguished Professor Sang Yup Lee, who has produced high-quality metabolic engineering and systems engineering research for decades, and made the hallmark chemicals map after seven years of studies.
The team presented a very detailed analysis on metabolic engineering for the production of a wide range of industrial chemicals, fuels, and materials. Surveying the current trends in the bio-based production of chemicals in industrial biotechnology, the team thoroughly examined the current status of industrial chemicals produced using biological and/or chemical reactions.
This comprehensive map is expected to serve as a blueprint for the visual and intuitive inspection of biological and/or chemical reactions for the production of interest from renewable resources. The team also compiled an accompanying poster to visually present the synthetic pathways of chemicals in the context of their microbial metabolism.
As metabolic engineering has become increasing powerful in addressing limited fossil resources, climate change, and other environmental issues, the number of microbially produced chemicals using biomass as a carbon source has increased substantially. The sustainable production of industrial chemicals and materials has been explored with micro-organisms as cell factories and renewable nonfood biomass as raw materials for alternative petroleum. The engineering of these micro-organism has increasingly become more efficient and effective with the help of metabolic engineering – a practice of engineering using the metabolism of living organisms to produce a desired metabolite.
With the establishment of systems metabolic engineering – the integration of metabolic engineering with tools and strategies from systems biology, synthetic biology and evolutionary engineering – the speed at which micro-organisms are being engineered has reached an unparalleled pace.
In order to evaluate the current state at which metabolically engineered micro-organisms can produce a large portfolio of industrial chemicals, the team conducted an extensive review of the literature and mapped them out on a poster. This resulting poster, termed the bio-based chemicals map, presents synthetic pathways for industrial chemicals, which consist of biological and/or chemical reactions.
Industrial chemicals and their production routes are presented in the context of central carbon metabolic pathways as these key metabolites serve as precursors for the chemicals to be produced. The resulting biochemical map allows the detection and analysis of optimal synthetic pathways for a given industrial chemical. In addition to the poster, the authors have compiled a list of chemicals that have successfully been produced using micro-organisms and a list of the corresponding companies producing them commercially. This thorough review of the literature and the accompanying analytical summary will be an important resource for researchers interested in the production of chemicals from renewable biomass sources.
Metabolically engineered micro-organisms have already made a huge contribution toward the sustainable production of chemicals using renewable resources. Professor Lee said he wanted a detailed survey of the current state and capacity of bio-based chemicals production.
“We are so excited that this review and poster will expand further discussion on the production of important chemicals through engineered micro-organisms and also combined biological and chemical means in a more sustainable manner,” he explained.
This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biofineries from the Ministry of Science and ICT through the National Research Foundation of Korea.
For further information, Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering at KAIST ( leesy@kaist.ac.kr , Tel: +82-42-350-3930)
Figure: Bio-based chemicals production through biological and chemical routes. This metabolic map describes representative chemicals that can be produced either by biological and/or chemical means. Red arrows represent chemical routes and blue arrows represent biological routes. Intermediate metabolites in the metabolism of a living organism can serve as a platform toward the production of industrially relevant chemicals. A more comprehensive map presented by the team can be found as a poster in the review.
2019.01.15 View 6570 -
Distinguished Alumni Awardees 2018
The KAIST Alumni Association (KAA) announced four recipients of the Distinguished Alumni Awards 2018. The Distinguished Alumni Awards recognize graduates who have achieved outstanding accomplishments in their professional and personal lives, and who have been an inspiration to fellow alumni and students in Korea and around the globe. Since the establishment of the award in 1992, a total of 99 alumni at home and abroad have been honored as recipients. The awards ceremony will take place during the New Year Alumni Reception on January 19 in Seoul.
Yeungnam University President Gil-Soo Sur (’75 MS, ’78 PhD in Chemistry) has demonstrated leadership in higher education and gained trust in academia for playing a leading role in educational innovation as well as serving as an educator who has fostered outstanding research talents for decades.
Professor Kwang-Soo Kim (’77 MS, ’79 PhD in Life Science) is the director of the Molecular Neurobiology Laboratory at McLean Hospital at Harvard Medical School. He has more than 20 years of experience investigating molecular and developmental neurobiology of the midbrain dopamine neuronal system. He has contributed to developing cell replacement therapy for Parkinson’s disease and has pioneered a generation of safe human-induced pluripotent stem cells through the direct delivery of reprogrammed proteins.
Young-Hwan Moon (’82 MS, ’87 PhD in Chemistry and Biomolecular Engineering) is the CEO of Coretech, which specializes in producing specialty gases and environmental catalysts required for chemical processes. He was recognized for enhancing national competence by securing competitive technology for manufacturing products.
Young-Hyun Jun (’84 MS, ’86 PhD in Electrical Engineering), the CEO of Samsung SDI, is a globally renowned expert in memory semiconductors. By bringing about innovative technology to enhance productivity and processes, he led Samsung Electronics to become the number one company at the global level in the field of semiconductors.
2019.01.14 View 3784 -
KAIST Presents Innovations at CES 2019
Ten of the most innovative technologies spun off from KAIST made a debut at the Consumer Electronics Show (CES) 2019, the world’s largest consumer electronics and IT exhibition being held in Las Vegas from January 8 to 11. The KAIST booth at the CES featured technologies made by KAIST research teams and five startup companies including LiBEST, Memslux, and Green Power. In particular, the KAIST Alumni Association invited 33 aspiring alumni entrepreneurs selected from the KAIST Startup Competition to the show.
At the exhibition, KAIST is presenting innovations in the fields of AI and Bio-IT convergence for the Fourth Industrial Revolution. These include real-time upscaling from Full HD to 4K UHD using AI deep learning-based convolutional neural networks (Professor Munchurl Kim, School of Electrical Engineering) and an AI conversation agent that responds to user’s emotions (Professor Soo-Young Lee, School of Electrical Engineering).
Other technologies include optimal drug target identification by cancer cell type through drug response prediction to be used in personalized cancer treatments (Professor Kwang-Hyun Cho, Department of Bio and Brain Engineering), a nanofiber-based color changing gas sensor with greater sensitivity than conventional paper-based color changing sensors (Professor Il-Doo Kim, Department of Materials Science and Engineering), and functional near-infrared spectroscopy (fNIRS) for brain imaging and muscle fatigue measurement (Professor Hyeonmin Bae, School of Electrical Engineering).
The KAIST booth also features startups founded by KAIST alumni including LiBEST with a flexible lithium polymer secondary cell optimized for smart wearable devices and Rempus with a high-performance lithium ion cell packaging technology for outstanding safety, high capacity, long life, and fast charging.
Green Power and Smart Radar Systems are also joining the booth with a highly efficient and eco-friendly wireless charging system for electrical cars, and a 4D image radar sensor that detects 3D images and speed in real time for applications in self-driving cars, drones, and security systems respectively.
Faculty-founded startup Memslux (CEO Jun-Bo Yoon, School of Electrical Engineering) is presenting a transparent surface light source solution for next-generation display devices.
Associate Vice President of Office of University-Industry Cooperation Kyung Cheol Choi said, “I believe that universities should play a role in connecting technological innovations to business startups for creating value at a global level. In that sense, it is a great opportunity to present innovative technologies from KAIST and promote outstanding KAIST startups at CES 2019. Hopefully, this experience will lead to joint R&D, investment, cooperation, and international technology transfer contracts with leading companies from around the world.”
Here are the five key technologies presented by KAIST at CES 2019.
2019.01.10 View 7051 -
President Shin to be Honored from Northwestern University
(KAIST President Sung-Chul Shin)
President Sung-Chul Shin has been named the recipient of the Distinguished Career Achievement Award 2019 for Alumni of Materials Science and Engineering at Northwestern University.
The awards committee announced last month that the committee decided to award President Shin in recognition of his significant contribution toward materials research, particularly in the field of magnetic materials, and also for the leadership he has demonstrated in higher education. The awards ceremony will take place on May 16 at Northwestern University.
President Shin earned his PhD in material physics at Northwestern in 1984 after completing his MS in condensed matter physics at KAIST in 1977. He is also a graduate of applied physics from Seoul National University.
President Shin, an accomplished scholar in the field of nanoscience and a pioneer of research in nanospinics, has held numerous fellowships including the American Physical Society and received scholarly honor from the Asian Union Magnetics Societies. His research focuses on the artificial synthesis and characterization of nonmagnetic materials, magnetic anisotropy, and magneto-optical phenomena. While studying at Northwestern, he produced novel superlattice multilayer thin film structures with bismuth and lead telluride, noting that they have similar structures.
With his expertise, he joined KAIST in 1989 to dedicate himself to academic contributions. During his professorship in the Department of Physics, he produced about 300 journal papers and 37 patents while fostering 80 graduate students. He served as the first president in Daegu-Gyeongbuk Scientific Technology Research Institute (DGIST) for six years from 2011.
2019.01.09 View 3113 -
NAEK Announces the New Members
The National Academy of Engineering of Korea (NAEK) announced its 42 new senior members and 61 new members who are actively engaging in academia and industry.
Professor Zong-Tae Bae from the College of Business and Ki-Chul Cha, the head of the KAIST Alumni Association and the CEO of Inbody were appointed as senior members of NAEK while Professor Hee Tae Jung from the Department of Chemical and Biomolecular Engineering was elected as a member of NAEK.
NAEK is a corporate body specializing in engineering. It is involved with promoting industrial competence and fostering human resources. Every year, it holds membership voting to select senior members among the members who demonstrated excellent research performance in universities, institutes, and companies.
To be elected to NAEK is quite prestigious, and considered as the highest professional honor in the engineering field. NAEK confers membership to those of who have more than 15 years of career experience. After a thorough evaluation, a member can be elevated to a senior member.
As of January 2019, NAEK has 285 senior members, 343 members, 432 emeritus members, and 71 foreign members.
2019.01.08 View 3068