A Biological Strategy Reveals How Efficient Brain ..
- A KAIST team’s mathematical modelling shows that the topographic tiling of cortical maps originates from bottom-up projections from the periphery. - Researchers have explained how the regularly structured topographic maps in the visual cortex of the brain could arise spontaneously to efficiently process visual information. This research provides a new framework for understanding functional architectures in the visual cortex during early developmental stages. A KAIST research team led by Professor Se-Bum Paik from the Department of Bio and Brain Engineering has demonstrated that the orthogonal organization of retinal mosaics in the periphery is mirrored onto the primary visual cortex and initiates the clustered topography of higher visual areas in the brain. This new finding provides advanced insights into the mechanisms underlying a biological strategy of brain circuitry for the efficient tiling of sensory modules. The study was published in Cell Reports on January 5. In higher mammals, the primary visual cortex is organized into various functional maps for neural tuning such as ocular dominance, orientation selectivity, and spatial frequency selectivity. Correlations between the topographies of different maps have been observed, implying their systematic organizations for the efficient tiling of sensory modules across cortical areas. These observations have suggested that a common principle for developing individual functional maps may exist. However, it has remained unclear how such topographical organizations could arise spontaneously in the primary visual cortex of various species. The research team found that the orthogonal organization in the primary visual cortex of the brain originates from the spatial organization in bottom-up feedforward projections. The team showed that an orthogonal relationship among sensory modules already exists in the retinal mosaics, and that this is mirrored onto the primary visual cortex to initiate the clustered topography. By analyzing the retinal ganglion cell mosaics data in cats and monkeys, the researchers found that the structure of ON-OFF feedforward afferents is organized into a topographic tiling, analogous to the orthogonal intersection of cortical tuning maps. Furthermore, the team’s analysis of previously published data collected on cats also showed that the ocular dominance, orientation selectivity, and spatial frequency selectivity in the primary visual cortex are correlated with the spatial profiles of the retinal inputs, implying that efficient tiling of cortical domains can originate from the regularly structured retinal patterns. Professor Paik said, “Our study suggests that the structure of the periphery with simple feedforward wiring can provide the basis for a mechanism by which the early visual circuitry is assembled.” He continued, “This is the first report that spatially organized retinal inputs from the periphery provide a common blueprint for multi-modal sensory modules in the visual cortex during the early developmental stages. Our findings would make a significant impact on our understanding the developmental strategy of brain circuitry for efficient sensory information processing.” This work was supported by the National Research Foundation of Korea (NRF). < Figure 1. The image depicts the retinal origin of functional maps of neural tuning in visual cortex. > < Figure 2. The image depicts the orthogonal intersection of cortical tuning maps that are initiated by the topographic tiling of retinal ganglion cell mosaics. > < Figure 3. The regularly structured retinal circuits provide a blueprint of the clustered topography of multiple tuning maps in the primary visual cortex. > Image credit: Professor Se-Bum Paik, KAIST Image usage restrictions: News organizations may use or redistribute this image, with proper attribution, as part of news coverage of this paper only. Publication: Song, M, et al. (2021) Projection of orthogonal tiling from the retina to the visual cortex. Cell Reports 34, 108581. Available online at https://doi.org/10.1016/j.celrep.2020.108581 Profile: Se-Bum Paik, Ph.D Assistant Professor sbpaik＠kaist.ac.kr http://vs.kaist.ac.kr/ VSNN Laboratory Department of Bio and Brain Engineering Program of Brain and Cognitive Engineering http://kaist.ac.kr Korea Advanced Institute of Science and Technology (KAIST) Daejeon, Republic of Korea Profile: Min Song Ph.D. Candidate night＠kaist.ac.kr Program of Brain and Cognitive Engineering Profile: Jaeson Jang, Ph.D. Researcher jaesonjang＠kaist.ac.kr Department of Bio and Brain Engineering, KAIST (END)
Professor Poong Hyun Seong Elected INSC Chair
< Professor Emeritus Poong Hyun Seong > Professor Emeritus Poong Hyun Seong from the Department of Nuclear and Quantum Engineering was elected as the Chairman of the International Nuclear Societies Council (INSC). His two-year term began on January 1. The INSC is an organization made up of nuclear societies all over the world, representing more than 80,000 nuclear professionals. The INSC founded in 1990 acts as a global forum to establish common goals of nuclear power usage, delivering the views and ideas of professionals throughout their regional societies. The INSC has advocated for nuclear power to be deemed an indispensable clean energy resources that can mitigate the climate change. The council has engaged in public awareness and publicity activities promoting the advantages of nuclear energy for developing next-generation power plants such as small nuclear reactors, local heating system, seawater desalination, and fair production of energy. Professor Seong is a globally renowned scholar in the fields of nuclear instrumentation control and human factor engineering. He retired last year after 30-year career at KAIST. He took on leadership roles in the Korea Nuclear Society and served as a member of the Korea Nuclear Safety and Security Commission as well as Atomic Energy Commission. A fellow at the America Nuclear Society, Professor Seong served as the first vice chair of the INSC and he received the Don Miller Award in 2019. The award established in 2009 by the American Nuclear Society in honor of former ANS President Don Miller is given to an individual who has made a significant contribution to the advancement of nuclear instrumentation and control of human-machine interfaces. He led the leadership role to help the Korean government steered into efficient and reasonable energy policymaking. More recently, as the Korean government decided to abandon nuclear energy, he actively opposed the government’s pivot. Professor Seong said, “Advanced countries like the US, UK, France, and Japan push forward the production of renewable energy by driving nuclear power plant under their pledges toward carbon neutrality by 2050. However, we are very concerned about the government’s policy shift to decrease the number of nuclear power plants while increasing the fossil fuel usage. I don’t think we can realize carbon neutrality by 2050 with the current policy.” (END)
DeepTFactor Predicts Transcription Factors
A deep learning-based tool predicts transcription factors using protein sequences as inputs A joint research team from KAIST and UCSD has developed a deep neural network named DeepTFactor that predicts transcription factors from protein sequences. DeepTFactor will serve as a useful tool for understanding the regulatory systems of organisms, accelerating the use of deep learning for solving biological problems. A transcription factor is a protein that specifically binds to DNA sequences to control the transcription initiation. Analyzing transcriptional regulation enables the understanding of how organisms control gene expression in response to genetic or environmental changes. In this regard, finding the transcription factor of an organism is the first step in the analysis of the transcriptional regulatory system of an organism. Previously, transcription factors have been predicted by analyzing sequence homology with already characterized transcription factors or by data-driven approaches such as machine learning. Conventional machine learning models require a rigorous feature selection process that relies on domain expertise such as calculating the physicochemical properties of molecules or analyzing the homology of biological sequences. Meanwhile, deep learning can inherently learn latent features for the specific task. A joint research team comprised of Ph.D. candidate Gi Bae Kim and Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering at KAIST, and Ye Gao and Professor Bernhard O. Palsson of the Department of Biochemical Engineering at UCSD reported a deep learning-based tool for the prediction of transcription factors. Their research paper “DeepTFactor: A deep learning-based tool for the prediction of transcription factors” was published online in PNAS. Their article reports the development of DeepTFactor, a deep learning-based tool that predicts whether a given protein sequence is a transcription factor using three parallel convolutional neural networks. The joint research team predicted 332 transcription factors of Escherichia coli K-12 MG1655 using DeepTFactor and the performance of DeepTFactor by experimentally confirming the genome-wide binding sites of three predicted transcription factors (YqhC, YiaU, and YahB). The joint research team further used a saliency method to understand the reasoning process of DeepTFactor. The researchers confirmed that even though information on the DNA binding domains of the transcription factor was not explicitly given the training process, DeepTFactor implicitly learned and used them for prediction. Unlike previous transcription factor prediction tools that were developed only for protein sequences of specific organisms, DeepTFactor is expected to be used in the analysis of the transcription systems of all organisms at a high level of performance. Distinguished Professor Sang Yup Lee said, “DeepTFactor can be used to discover unknown transcription factors from numerous protein sequences that have not yet been characterized. It is expected that DeepTFactor will serve as an important tool for analyzing the regulatory systems of organisms of interest.” This work was supported by the Technology Development Program to Solve Climate Changes on Systems Metabolic Engineering for Biorefineries from the Ministry of Science and ICT through the National Research Foundation of Korea. < Figure: The network architecture of DeepTFactor. An input protein sequence is processed using three parallel subnetworks. > -Publication Gi Bae Kim, Ye Gao, Bernhard O. Palsson, and Sang Yup Lee. DeepTFactor: A deep learning-based tool for the prediction of transcription factors. (https://doi.org/10.1073/pnas202117118) -Profile Distinguished Professor Sang Yup Lee leesy＠kaist.ac.kr Metabolic &Biomolecular Engineering National Research Laboratory http://mbel.kaist.ac.kr Department of Chemical and Biomolecular Engineering KAIST
Extremely Stable Perovskite Nanoparticles Films fo..
< Figure 1:Photographs of large-area siloxane-encapsulated perovskite nanoparticle films. The left one indicates the perfect color converting property on commercial mobile phone screens. The right one presents color converted films under versatile bending states. > Researchers have reported an extremely stable cross-linked perovskite nanoparticle that maintains a high photoluminescence quantum yield (PLQY) for 1.5 years in air and harsh liquid environments. This stable material’s design strategies, which addressed one of the most critical problems limiting their practical application, provide a breakthrough for the commercialization of perovskite nanoparticles in next-generation displays and bio-related applications. According to the research team led by Professor Byeong-Soo Bae, their development can survive in severe environments such as water, various polar solvents, and high temperature with high humidity without additional encapsulation. This development is expected to enable perovskite nanoparticles to be applied to high color purity display applications as a practical color converting material. This result was published as the inside front cover article in Advanced Materials. Perovskites, which consist of organics, metals, and halogen elements, have emerged as key elements in various optoelectronic applications. The power conversion efficiency of photovoltaic cells based on perovskites light absorbers has been rapidly increased. Perovskites are also great promise as a light emitter in display applications because of their low material cost, facile wavelength tunability, high (PLQY), very narrow emission band width, and wider color gamut than inorganic semiconducting nanocrystals and organic emitters. Thanks to these advantages, perovskites have been identified as a key color-converting material for next-generation high color-purity displays. In particular, perovskites are the only luminescence material that meets Rec. 2020 which is a new color standard in display industry. However, perovskites are very unstable against heat, moisture, and light, which makes them almost impossible to use in practical applications. To solve these problems, many researchers have attempted to physically prevent perovskites from coming into contact with water molecules by passivating the perovskite grain and nanoparticle surfaces with organic ligands or inorganic shell materials, or by fabricating perovskite-polymer nanocomposites. These methods require complex processes and have limited stability in ambient air and water. Furthermore, stable perovskite nanoparticles in the various chemical environments and high temperatures with high humidity have not been reported yet. The research team in collaboration with Seoul National University develops siloxane-encapsulated perovskite nanoparticle composite films. Here, perovskite nanoparticles are chemically crosslinked with thermally stable siloxane molecules, thereby significantly improving the stability of the perovskite nanoparticles without the need for any additional protecting layer. Siloxane-encapsulated perovskite nanoparticle composite films exhibited a high PLQY (> 70％) value, which can be maintained over 600 days in water, various chemicals (alcohol, strong acidic and basic solutions), and high temperatures with high humidity (85℃/85％). The research team investigated the mechanisms impacting the chemical crosslinking and water molecule-induced stabilization of perovskite nanoparticles through various photo-physical analysis and density-functional theory calculation. The research team confirmed that displays based on their siloxane-perovskite nanoparticle composite films exhibited higher PLQY and a wider color gamut than those of Cd-based quantum dots and demonstrated perfect color converting properties on commercial mobile phone screens. Unlike what was commonly believed in the halide perovskite field, the composite films showed excellent bio-compatibility because the siloxane matrix prevents the toxicity of Pb in perovskite nanoparticle. By using this technology, the instability of perovskite materials, which is the biggest challenge for practical applications, is greatly improved through simple encapsulation method. “Perovskite nanoparticle is the only photoluminescent material that can meet the next generation display color standard. Nevertheless, there has been reluctant to commercialize it due to its moisture vulnerability. The newly developed siloxane encapsulation technology will trigger more research on perovskite nanoparticles as color conversion materials and will accelerate early commercialization,” Professor Bae said. This work was supported by the Wearable Platform Materials Technology Center (WMC) of the Engineering Research Center (ERC) Project, and the Leadership Research Program funded by the National Research Foundation of Korea. < Figure 2. Schematic illustration of the water-induced stabilization of siloxane-encapsulated perovskite nanoparticles. > -Publication: Junho Jang, Young-Hoon Kim, Sunjoon Park, Dongsuk Yoo, Hyunjin Cho, Jinhyeong Jang, Han Beom Jeong, Hyunhwan Lee, Jong Min Yuk, Chan Beum Park, Duk Young Jeon, Yong-Hyun Kim, Byeong-Soo Bae, and Tae-Woo Lee. “Extremely Stable Luminescent Crosslinked Perovskite Nanoparticles under Harsh Environments over 1.5 Years” Advanced Materials, 2020, 2005255. https://doi.org/10.1002/adma.202005255. Link to download the full-text paper: https://onlinelibrary.wiley.com/doi/10.1002/adma.202005255 -Profile: Prof. Byeong-Soo Bae (Corresponding author) bsbae＠kaist.ac.kr Lab. of Optical Materials & Coating Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology (KAIST)
A Comprehensive Review of Biosynthesis of Inorgani..
< Distinguished Professor Lee and Dr. Yoojin Choi > There are diverse methods for producing numerous inorganic nanomaterials involving many experimental variables. Among the numerous possible matches, finding the best pair for synthesizing in an environmentally friendly way has been a longstanding challenge for researchers and industries. A KAIST bioprocess engineering research team led by Distinguished Professor Sang Yup Lee conducted a summary of 146 biosynthesized single and multi-element inorganic nanomaterials covering 55 elements in the periodic table synthesized using wild-type and genetically engineered microorganisms. Their research highlights the diverse applications of biogenic nanomaterials and gives strategies for improving the biosynthesis of nanomaterials in terms of their producibility, crystallinity, size, and shape. The research team described a 10-step flow chart for developing the biosynthesis of inorganic nanomaterials using microorganisms and bacteriophages. The research was published at Nature Review Chemistry as a cover and hero paper on December 3. “We suggest general strategies for microbial nanomaterial biosynthesis via a step-by-step flow chart and give our perspectives on the future of nanomaterial biosynthesis and applications. This flow chart will serve as a general guide for those wishing to prepare biosynthetic inorganic nanomaterials using microbial cells,” explained Dr.Yoojin Choi, a co-author of this research. Most inorganic nanomaterials are produced using physical and chemical methods and biological synthesis has been gaining more and more attention. However, conventional synthesis processes have drawbacks in terms of high energy consumption and non-environmentally friendly processes. Meanwhile, microorganisms such as microalgae, yeasts, fungi, bacteria, and even viruses can be utilized as biofactories to produce single and multi-element inorganic nanomaterials under mild conditions. After conducting a massive survey, the research team summed up that the development of genetically engineered microorganisms with increased inorganic-ion-binding affinity, inorganic-ion-reduction ability, and nanomaterial biosynthetic efficiency has enabled the synthesis of many inorganic nanomaterials. Among the strategies, the team introduced their analysis of a Pourbaix diagram for controlling the size and morphology of a product. The research team said this Pourbaix diagram analysis can be widely employed for biosynthesizing new nanomaterials with industrial applications.Professor Sang Yup Lee added, “This research provides extensive information and perspectives on the biosynthesis of diverse inorganic nanomaterials using microorganisms and bacteriophages and their applications. We expect that biosynthetic inorganic nanomaterials will find more diverse and innovative applications across diverse fields of science and technology.” Dr. Choi started this research in 2018 and her interview about completing this extensive research was featured in an article at Nature Career article on December 4. < Single- and two-element map of inorganic nanomaterials biosynthesized using microbial cells and bacteriophages. Fifty-one elements (excluding H, C, N and O) have been used in inorganic nanomaterial synthesis using microbial cells and bacteriophages. White spaces indicate that biosynthesis of inorganic nanomaterials comprising the corresponding elements has not yet been reported. Red denotes unary or binary metal/non-metal nanomaterials that have been biosynthesized. Dark blue denotes metal/non-metal oxides that have been biosynthesized. Light blue indicates biosynthesized metal hydroxides. Light purple indicates that metal/non-metal phosphates have been biosynthesized. Orange indicates that metal carbonates have been biosynthesized. All inorganic nanomaterials biosynthesized using microbial cells and bacteriophages are listed in the paper. > -Profile Distinguished Professor Sang Yup Lee leesy＠kaist.ac.kr Metabolic &Biomolecular Engineering National Research Laboratory http://mbel.kaist.ac.kr Department of Chemical and Biomolecular Engineering KAIST
Three Professors Named to Highly Cited Researchers..
< Distinguished Professor Chang, Distinguished Professor Lee, and Professor Eom (from left) > Distinguished Professor Sukbok Chang from the Department of Chemistry, Distinguished Professor Sang-Yup Lee from the Department of Chemical & Biomolecular Engineering, and Professor Jiyong Eom from the College of Business were named to Clarivate’s Highly Cited Researchers 2020 list. Clarivate announced the researchers who rank in the top 1％ of citations by field and publication year in the Web of Science citation index. A total of 6,167 researchers from more than 60 countries were listed this year and 37 Korean scholars made the list. The methodology that determines the “Who’s Who” of influential researchers draws on data and analyses performed by bibliometric experts and data scientists at the Institute for Scientific Information at Clarivate. It also uses the tallies to identify the countries and research institutions where these scientific elite are based. More than 6,000 researchers from 21 fields in the sciences, social sciences, and cross field categories were selected based on the number of highly cited papers they produced over an 11-year period from January 2009 to December 2019. Professor Chang made the list six years in a row, while Professor Lee made it for four consecutive years, and Professor Eom for the last two years. Professor Chang’s group (http://sbchang.kaist.ac.kr) investigates catalytic hydrocarbon functionalization. Professor Lee (http://mbel.kaist.ac.kr) is a pioneering scholar in the field of metabolic engineering, systems, and synthetic biology. Professor Eom’s (https://kaistceps.quv.kr) research extends to energy and environmental economics and management, energy big data, and green information systems.
Simulations Open a New Way to Reverse Cell Aging
Turning off a newly identified enzyme could reverse a natural aging process in cells. Research findings by a KAIST team provide insight into the complex mechanism of cellular senescence and present a potential therapeutic strategy for reducing age-related diseases associated with the accumulation of senescent cells. Simulations that model molecular interactions have identified an enzyme that could be targeted to reverse a natural aging process called cellular senescence. The findings were validated with laboratory experiments on skin cells and skin equivalent tissues, and published in the Proceedings of the National Academy of Sciences (PNAS). “Our research opens the door for a new generation that perceives aging as a reversible biological phenomenon,” says Professor Kwang-Hyun Cho of the Department of Bio and Brain engineering at the Korea Advanced Institute of Science and Technology (KAIST), who led the research with colleagues from KAIST and Amorepacific Corporation in Korea. Cells respond to a variety of factors, such as oxidative stress, DNA damage, and shortening of the telomeres capping the ends of chromosomes, by entering a stable and persistent exit from the cell cycle. This process, called cellular senescence, is important, as it prevents damaged cells from proliferating and turning into cancer cells. But it is also a natural process that contributes to aging and age-related diseases. Recent research has shown that cellular senescence can be reversed. But the laboratory approaches used thus far also impair tissue regeneration or have the potential to trigger malignant transformations. Professor Cho and his colleagues used an innovative strategy to identify molecules that could be targeted for reversing cellular senescence. The team pooled together information from the literature and databases about the molecular processes involved in cellular senescence. To this, they added results from their own research on the molecular processes involved in the proliferation, quiescence (a non-dividing cell that can re-enter the cell cycle) and senescence of skin fibroblasts, a cell type well known for repairing wounds. Using algorithms, they developed a model that simulates the interactions between these molecules. Their analyses allowed them to predict which molecules could be targeted to reverse cell senescence. They then investigated one of the molecules, an enzyme called PDK1, in incubated senescent skin fibroblasts and three-dimensional skin equivalent tissue models. They found that blocking PDK1 led to the inhibition of two downstream signalling molecules, which in turn restored the cells’ ability to enter back into the cell cycle. Notably, the cells retained their capacity to regenerate wounded skin without proliferating in a way that could lead to malignant transformation. The scientists recommend investigations are next done in organs and organisms to determine the full effect of PDK1 inhibition. Since the gene that codes for PDK1 is overexpressed in some cancers, the scientists expect that inhibiting it will have both anti-aging and anti-cancer effects. < Figure: The scientists conducted what is known as an ensemble model simulation to identify molecules that could be targeted to reverse cell senescence. They then used the model to predict the effects of inhibiting PDK1 in senescent cells, and confirmed the results in lab-cultured cells and skin equivalent tissue models. > -Profile Professor Kwang-Hyun Cho Laboratory for Systems Biology and Bio-Inspired Engineering http://sbie.kaist.ac.kr Department of Bio and Brain Engineering KAIST
In Memory of Professor Dong-Soo Kim
Pioneering geotechnical engineer Dong-Soo Kim dies at 59 < The late Professor Dong-Soo Kim at the Department of Civil and Environmental Engineering. > The Department of Civil and Environmental Engineering lost a pioneering scholar in geotechnical engineering, Professor Dong-Soo Kim. Professor Kim died on November 3, after a one-and-a-half-year battle with a brain tumor. He was 59. Known for his piercing insight and infectious enthusiasm for the deepest questions in geotechnical science and engineering, Professor Kim built an extraordinary academic career while working at KAIST for 26 years. Professor Kim paved the way for establishing the geo-centrifuge experiment facilities at KAIST as part of the KOCED (Korea Construction Engineering Development Collaboratory Management Institute) Projects funded by the Ministry of Land, Infrastructure and Transport. He also served as director of the KOCED Geo-Centrifuge Center. “He made significant contributions to the growth of the department since his joining and he was at the forefront of the globalization of the department. He passed away so early leaving behind so many projects,” lamented Professor Emeritus Chung-Bang Yun. “Professor Kim insisted on lecturing despite his serious illness. He wanted to play his part so gracefully for his students until his last days,” said Professor Hyo-Gyong Kwak, the head of the department who was also a close colleague of 25 years. “His captivating warm smile and unwavering mentorship and guidance will be missed by students and faculty alike. We lost an exemplary leader, mentor, colleague, and friend.” One of his colleagues, Professor Gye-Chun Cho said, “We have lost a great professor and colleague in civil engineering worldwide. His impact and legacy will be remembered forever.” Joining the KAIST faculty in 1994, he began his academic career at the Polytechnique University, New York for three years after earning his PhD at the University of Texas at Austin in 1991. He finished his BS and MS at Seoul National University in 1983 and 1985 respectively. While at KAIST, he led the Soil Dynamics Lab in 1994 and researched on site characterization via field and lab tests. He also conducted geotechnical centrifuge tests on earthquake and offshore geotechnical problems. His research team studied the seismic design of geotechnical structures and explored the non-destructive testing and evaluation of civil structures. Professor Kim made profound contributions to understanding fundamental geotechnical engineering problems. More recently, his lab investigated physical modeling using the geo-centrifuge testing machine that could simulate field geotechnical problems on small-scale models. Professor Kim’s perseverance, deep curiosity, and enthusiasm for discovery served him well in his roles as a teacher, mentor, and colleague in the department and beyond. “I thought of him as an elder brother who fully understand everything with generous mind,” said Professor Haeng-Ki Lee, former head of the department. “I will never forget the hiking trip to Halla Mountain in Jeju last summer. He continuously cheered on the junior professors. Without him, we could not have made it to the summit. His support and encouragement always led us to produce good results and achievement in the labs,” remembered Professor Youngchul Kim. Taking great delight in helping young scientists, he inspired colleagues and students to find their own eureka moments. To professors like Jong-In Han and Ayoung Kim, he was the role model they hope to be due to his rigorous scholarship and generous character. Upon his passing, Professor Jaewook Myung reviewed all the emails he and Professor Kim has sent starting from his undergraduate days at KAIST. “He was my guiding light. He always listened attentively to my struggles from my undergraduate days and advised me very warmly.” Professor Kim was also known for his key role in the Korean Geotechnical Society. His unmatched leadership led him to serve as the Chair of the Organizing Committee for the 19th International Conference on Soil Mechanics and Geotechnical Engineering in Seoul in 2017. He was the General Secretary of the 5th International Symposium on Deformation Characteristics of Geomaterials. He also served as a chair of the ISSSMGE TC 104 committee. Professor Kim successfully carried out numerous projects with his research team and supervised more than 60 graduate students. For current students under his supervision, it is still tough to acknowledge the loss of their professor. Master candidate Yeonjun Kim feels lost moving forward. PhD candidate Junsik Bae said that it is like a bad dream and he feels Professor Kim will still be in his lab whenever he goes inside. One of the staff members who worked with him, Byeol-Nim Cha, remembered that Professor Kim always entered the office with a big smile. “He always asked me how I am doing,” Cha added. Professor Kim’s trailblazing research was recognized with several awards and honors. Cited as a Top 100 Scientist by the International Biographical Center (IBC) in 2008, Professor Kim received the Young Presidential Research Award from the Korean Academy of Science and Technology in 2002, the Korean Presidential Award on Civil Engineer’s Day in 2011, and the Telford Premium Rewards in 2018. Throughout his career, he authored or co-authored 321 papers in international journals and conference proceedings, and 278 papers in domestic journals and conferences. President of the Korean Geotechnical Society Choong-gi Chung also eulogized him, “Above his impressive professional contributions, Professor Kim will be remembered forever for his generosity, simplicity, playfulness, and his smile.” Professor Kim is survived by his wife, son, and daughter.
Team USRG’s Winning Streak Continues at the AI Gra..
< Team USRG won the AI Grand Challenge 2020 for the second consecutive year. > Team USRG (Unmanned Systems Research Group) led by Professor Hyunchul Shim from the School of Electrical Engineering has won the AI Grand Challenge 2020 held on Nov. 23 at Kintex in Ilsan, Kyonggi-do for the second consecutive year. The team received 7.7 million KRW in research funding from the Ministry of Science and ICT, the organizer of the challenge. The team took a little over two minutes to complete the rescue operation mission of the challenge. The mission included swerving around seven obstacles, airdropping an aid package, and safely landing after identifying the landing spot. Their drone is the only one that successfully passed through a 10-meter tunnel out of five pre-qualified teams: three from universities and two from companies. The AI Grand Challenge, which began in 2017, was designed to promote AI technology and its applications for addressing high-risk technical challenges, especially for conducting complex disaster relief operations. For autonomous flying drones, swerving to avoid objects has always been an essential skill and a big challenge. For their flawless performance in the rescue operation, the team loaded an AI algorithm and upgraded their drone by improving the LiDAR-based localization system and a stronger propulsion system to carry more sensors. The drone weighs 2.4 kg and carries a small yet powerful computer with a GPU. This AI-powered drone can complete rescue missions more efficiently in complicated and disastrous environments by precisely comprehending where the drone should go without needing GPS. The team also designed an all-in-one prop guard and installed a gripper onto the bottom of the drone to hold the aid package securely. “We tried hard to improve our localization system better to resolve issues we had in the previous event,” said Professor Shim. Two PhD candidates, Han-Sob Lee and Bo-Sung Kim played a critical role in developing this drone. After their two-year winning streak, their prize money now totals 2.4 billion KRW, equivalent to the winning prize of the DARPA Challenge. As the winning team, they will collaborate with other champions at the AI track challenge to develop rescue mission technology for a more complex environment. “The importance of AI technology is continuing to grow and the government is providing large amounts of funding for research in this field. We would like to develop very competitive technology that will work in the real world,” Professor Shim added. His group is investigating a wide array of AI technologies applicable to unmanned vehicles including indoor flying drones, self-driving cars, delivery robots, and a tram that circles the campus. < Two PhD candidates, Han-Sob Lee and Bo-Sung Kim make a final touch for the competition. >
Feel the Force with ElaStick
ElaStick, a handheld variable stiffness display, renders the dynamic haptic response of a flexible object Haptic controllers play an important role in providing rich and immersive virtual reality experiences. Professor Andrea Bianchi’s team in the Department of Industrial Design recreated the haptic response of flexible objects made of different materials and with different shapes by changing the stiffness of a custom-controller – ElaStick. ElaStick is a portable hand-held force-feedback controller that is capable of rendering the illusion of how flexible and deformable objects feel when held in the hand. This VR haptic controller can change its stiffness in two directions independently and continuously. Since providing haptic feedback enhances the VR experience, researchers have suggested numerous approaches for rendering the physical properties of virtual objects - such as weights, the movement of mass, impacts, and damped oscillations. The research team designed a new mechanism based on a quaternion joint and four variable-stiffness tendons. The quaternion joint is a two-DoF bending joint that enables ElaStick to bend and oscillate in any direction using a pair of tendons with varying stiffness. In fact, each tendon around the joint is made of a series of elastic rubber bands and inelastic fishing lines and can vary its stiffness by changing the proportion of the two materials. Thanks to these structures, each pair of tendons can behave independently, controlling the anisotropic characteristics of the entire device. “The main challenge was to implement the mechanism to control the stiffness while maintaining independence between deformations in two perpendicular directions,” said Professor Bianchi. The research team successfully measured the relative threshold of human perception on the stiffness of a handheld object. The results showed that the just-noticeable difference (JND) of human perception of stiffness is at most about 30％ of the change from the initial value. It also found that appropriate haptic responses significantly enhance the quality of the VR experience. The research team surveyed the perceived realism, immersion, and enjoyment of participants after they played with various flexible objects in VR. “It is meaningful that the haptic feedback of a flexible object was mechanically reproduced and its effectiveness in VR was proven. ElaStick has succeeded in implementing a novel mechanism to recreate the dynamic response of flexible objects that mimic real ones, suggesting a new category of haptic feedback that can be provided in VR,” explained Professor Bianchi. The team plans to extend the ElaStick’s applications, from being used merely as a game controller to driving simulations, medical training, and many other digital contexts. This research, led by MS candidate Neung Ryu, won the Best Paper Award at the ACM UIST 2020 (the ACM Symposium on User Interface Software & Technology) last month. -Profile Professor Andrea Bianchi Makinteract.kaist.ac.kr Department of Industrial Design KAIST
‘WalkON Suit 4’ Releases Paraplegics from Wheelcha..
- KAIST Athletes in ‘WalkON Suit 4’ Dominated the Cybathlon 2020 Global Edition. - Paraplegic athletes Byeong-Uk Kim and Joohyun Lee from KAIST’s Team Angel Robotics won a gold and a bronze medal respectively at the Cybathlon 2020 Global Edition last week. ‘WalkON Suit 4,’ a wearable robot developed by the Professor Kyoungchul Kong’s team from the Department of Mechanical Engineering topped the standings at the event with double medal success. Kim, the former bronze medallist, clinched his gold medal by finishing all six tasks in 3 minutes and 47 seconds, whereas Lee came in third with a time of 5 minutes and 51 seconds. TWIICE, a Swiss team, lagged 53 seconds behind Kim’s winning time to be the runner-up. < Byeong-Uk Kim (left) and Joohyun Lee (right) > Cybathlon is a global championship, organized by ETH Zurich, which brings together people with physical disabilities to compete using state-of-the-art assistive technologies to perform everyday tasks. The first championship was held in 2016 in Zurich, Switzerland. Due to the COVID-19 pandemic, the second championship was postponed twice and held in a new format in a decentralized setting. A total of 51 teams from 20 countries across the world performed the events in their home bases in different time zones instead of traveling to Zurich. Under the supervision of a referee and timekeeper, all races were filmed and then reviewed by judges. KAIST’s Team Angel Robotics participated in the Powered Exoskeleton Race category, where nine pilots representing five nations including Korea, Switzerland, the US, Russia, and France competed against each other. The team installed their own arena and raced at the KAIST Main Campus in Daejeon according to the framework, tasks, and rules defined by the competition committee. The two paraplegic pilots were each equipped with exoskeletal devices, the WalkON Suit 4, and undertook six tasks related to daily activities. The WalkON Suit 4 recorded the fastest walking speed for a complete paraplegic ever reported. For a continuous walk, it achieved a maximum speed of 40 meters per minute. This is comparable to the average walking pace of a non-disabled person, which is around two to four kilometers per hour. The research team raised the functionality of the robot by adding technology that can observe the user’s level of anxiety and external factors like the state of the walking surface, so it can control itself intelligently. The assistive functions a robot should provide vary greatly with the environment, and the WalkON Suit 4 made it possible to analyze the pace of the user within 30 steps and provide a personally optimized walking pattern, enabling a high walking speed. < WalkON Suit 4 > The six tasks that Kim and Lee had to complete were:1) sitting and standing back up, 2) navigating around obstacles while avoiding collisions, 3) stepping over obstacles on the ground, 4) going up and down stairs, 5) walking across a tilted path, and 6) climbing a steep slope, opening and closing a door, and descending a steep slope. < Overview of the Powered Exoskeleton Race. > Points were given based on the accuracy of each completed task, and the final scores were calculated by adding all of the points that were gained in each attempt, which lasted 10 minutes. Each pilot was given three opportunities and used his/her highest score. Should pilots have the same final score, the pilot who completed the race in the shortest amount of time would win. Kim said in his victory speech that he was so thrilled to see all his and fellow researchers’ years of hard work paying off. “This will be a good opportunity to show how outstanding Korean wearable robot technologies are,” he added. Lee, who participated in the competition for the first time, said, “By showing that I can overcome my physical disabilities with robot technology, I’d like to send out a message of hope to everyone who is tired because of COVID-19”. Professor Kong’s team collaborated in technology development and pilot training with their colleagues from Angel Robotics Co., Ltd., Severance Rehabilitation Hospital, Yeungnam University, Stalks, and the Institute of Rehabilitation Technology. Footage from the competition is available at the Cybathlon’s official website. (END)
Researchers Control Multiple Wavelengths of Light ..
KAIST researchers have synthesized a collection of nanoparticles, known as carbon dots, capable of emitting multiple wavelengths of light from a single particle. Additionally, the team discovered that the dispersion of the carbon dots, or the interparticle distance between each dot, influences the properties of the light the carbon dots emit. The discovery will allow researchers to understand how to control these carbon dots and create new, environmentally responsible displays, lighting, and sensing technology. Research into nanoparticles capable of emitting light, such as quantum dots, has been an active area of interest for the last decade and a half. These particles, or phosphors, are nanoparticles made out of various materials that are capable of emitting light at specific wavelengths by leveraging quantum mechanical properties of the materials. This provides new ways to develop lighting and display solutions as well as more precise detection and sensing in instruments. As technology becomes smaller and more sophisticated, the usage of fluorescent nanoparticles has seen a dramatic increase in many applications due to the purity of the colors emitting from the dots as well as their tunability to meet desired optical properties. Carbon dots, a type of fluorescent nanoparticles, have seen an increase in interest from researchers as a candidate to replace non-carbon dots, the construction of which requires heavy metals that are toxic to the environment. Since they are made up of mostly carbon, the low toxicity is an extremely attractive quality when coupled with the tunability of their inherent optical properties. Another striking feature of carbon dots is their capability to emit multiple wavelengths of light from a single nanoparticle. This multi-wavelength emission can be stimulated under a single excitation source, enabling the simple and robust generation of white light from a single particle by emitting multiple wavelengths simultaneously. Carbon dots also exhibit a concentration-dependent photoluminescence. In other words, the distance between individual carbon dots affects the light that the carbon dots subsequently emit under an excitation source. These combined properties make carbon dots a unique source that will result in extremely accurate detection and sensing. This concentration-dependency, however, had not been fully understood. In order to fully utilize the capabilities of carbon dots, the mechanisms that govern the seemingly variable optical properties must first be uncovered. It was previously theorized that the concentration-dependency of carbon dots was due to a hydrogen bonding effect. Now, a KAIST research team, led by Professor Do Hyun Kim of the Department of Chemical and Biomolecular Engineering has posited and demonstrated that the dual-color-emissiveness is instead due to the interparticle distances between each carbon dot. The research was published in the 36th Issue of Physical Chemistry Chemical Physics. First author of the paper, PhD candidate Hyo Jeong Yoo, along with Professor Kim and researcher Byeong Eun Kwak, examined how the relative light intensity of the red and blue colors changed when varying the interparticle distances, or concentration, of the carbon dots. They found that as the concentration was adjusted, the light emitted from the carbon dots would transform. By varying the concentration, the team was able to control the relative intensity of the colors, as well as emit them simultaneously to generate a white light from a single source (See Figure). “The concentration-dependence of the photoluminescence of carbon dots on the change of the emissive origins for different interparticle distances has been overlooked in previous research. With the analysis of the dual-color-emission phenomenon of carbon dots, we believe that this result may provide a new perspective to investigate their photoluminescence mechanism,” Yoo explained. The newly analyzed ability to control the photoluminescence of carbon dots will likely be heavily utilized in the continued development of solid-state lighting applications and sensing. < Figure. Photoluminescence change of dual-color-emissive carbon dots (CDs) depending on their concentration. Blue- and red-emissions show different contributions with different interparticle distances. > Publication: Yoo, H. J., Kwak, B. E., and Kim. D. H. (2020) Interparticle distance as a key factor for controlling the dual-emission properties of carbon dots. Physical Chemistry Chemical Physics, Issue 36, Pages 20227-20237. Available online at https://doi.org/10.1039/d0cp02120b Profile: Do Hyun Kim, Sc.D. Professor dokim＠kaist.ac.kr http://procal.kaist.ac.kr/ Process Analysis Laboratory Department of Chemical and Biomolecular Engineering https://www.kaist.ac.kr Korea Advanced Institute of Science and Technology (KAIST) Daejeon, Republic of Korea (END)