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Photonic Capsules for Injectable Laser Resonators
A KAIST research group presented photonic capsules for injectable laser resonators using microfluidic technology. The capsule’s diameter is comparable to a human hair and stable in gas and liquid media, so it is injectable into any target volume.
The research group headed by Professor Shin-Hyun Kim in the Department of Chemical and Biomolecular Engineering applied an interesting optical property from nature. Professor Kim, who has dived deep into photonic materials research inspired from nature such as the Morpho butterfly, used a trait of beetles this time.
Chrysina gloriosa, commonly known as the glorious beetle, shows a green color similar to leaves when illuminated by left-handed, circularly-polarized light while showing no color with right-handed, circularly-polarized light. This unique optical feature helps the beetles communicate with each other and protects them from predators.
The principle behind this interesting optical property of the beetles relies on helical nanostructures with left-handedness that are present on the shell of the beetles. The helical structures reflect a circularly-polarized light with the same handedness of the helix at the wavelength selected by the helical pitch through optical interference.
Such helical nanostructures can be artificially created using liquid crystals (LCs). LCs with a helical arrangement are referred to as cholesteric LCs (CLCs). The CLCs exhibit the polarization-dependent reflection of light in the same manner as the beetles and have been used for various photonic applications.
In particular, CLCs have been cast to a film format that serves as mirrorless laser resonators, unlike conventional lasing systems. However, the film-type CLCs are large in size and show unidirectional emission, which restricts the use of CLC resonators in microenvironments.
To overcome these limitations, Professor Kim’s group has encapsulated the CLCs with dual shells using microfluidic technology. The inner shell is a water layer that promotes the alignment of LC molecules and the outer shell is an elastic polymer layer that secures capsule stability and enables reversible mechanical deformation. The spherical symmetry of the capsules enables omnidirectional laser emissions. Moreover, laser intensity and lasing direction can be further controlled by deforming the capsules, while its wavelength remains tunable. This new type of CLC laser resonator is promising for laser treatments in various biomedical applications.
Professor Kim said, “The helical nanostructure used in the laser resonator resembles that of the shell of chrysina gloriosa. Humans learn from nature and engineer materials to create something unprecedented.”
This research was led by graduate student Sang Seok Lee and an article entitled “Wavelength-tunable and shape-reconfigurable photonic capsule resonators containing cholesteric liquid crystals” was published online on June 22, in Science Advances.
Figure 1. Chrysina gloriosa illuminated by left-handed (left panel) and right-handed (right panel) circularly-polarized lights.
(Image source: https://doi.org/10.1016/j.cub.2010.05.036 , permitted for reuse in news media)
Figure 2. Composition (left panel) and optical microscopy image (right panel) of the capsule-type laser resonator
2018.07.05 View 9462 -
Professor Suh Chosen for IT Young Engineer Award
(The ceremony photo of Professor Changho Suh)
Professor Changho Suh from the School of Electrical Engineering received the IT Young Engineer Award on June 28. This award is hosted by the Institute of Electrical and Electronics Engineers (IEEE) and the Institute of Electrical and Information Engineers (IEIE) and funded by the Haedong Science Foundation.
The IT Young Engineer Award is given to researchers under the age of 40 in Korea. The selection criteria include the researches’ technical practicability, their social and environmental contributions, and their creativity.
Professor Suh has shown outstanding academic performance in the field of telecommunications, distributed storage, and artificial intelligence and he has also contributed to technological commercialization. He published 23 papers in SCI journals and ten papers at top-level international conferences including the Conference on Neural Information Processing Systems and the International Conference on Machine Learning. His papers were cited more than 4,100 times. He has also achieved 30 international patent registrations.
Currently, he is developing an autonomous driving system using an AI-tutor and deep learning technology.
Professor Suh said, “It is my great honor to receive the IT Young Engineer Award. I strive to continue guiding students and carrying out research in order to make a contribution to the fields of IT and AI.”
2018.07.04 View 9760 -
KAIST Student Wins HRI Student Design Competition
(From left: Jason Jangho Choi, Hyunjin Ku and Wonkyung Do)
Hyunjin Ku from the Department of Mechanical Engineering won the first prize at the Student Design Competition of Human-Robot-Interaction (HRI) 2018 which was held in Chicago.
Ku teamed up with undergrad students from Seoul National University (Jason Jangho Choi, Soomin Lee, Sunho Jang, and Wonkyung Do) and submitted Shelly, a tortoise-like robot for one-to-many interactions with children.
Figure 1. Shelly, a tortoise-like robot for one-to-many interactions with children
In the Student Design Competition of the HRI, students from around the globe can submit designs for their interactive robotic objects. The competition focused on human-agent interactions and practical applications.
Ku conducted the research while doing an internship at NAVER Labs. Her research on learning robot abuse with Shelly was published in IEEE Spectrum.
[YTN Science]
https://www.youtube.com/watch?v=n5KVwgBk0wk
[HRI 2018 Website]
http://humanrobotinteraction.org/2018/sdc/
[IEEE Spectrum]
https://spectrum.ieee.org/automaton/robotics/robotics-hardware/shelly-robotic-tortoise-helps-kids-learn-that-robot-abuse-is-a-bad-thing
2018.07.02 View 8315 -
ICT Volunteer Corps Off to Africa
A volunteer corps made up of students will take part in ICT education services in Ethiopia, Tanzania, and Uganda. KAIST students have been volunteering with the ICT education program in Africa since 2015.
The volunteer corps will be made up of 51 students from 13 teams and will be conducting services for a month through the end of July at Addis Ababa Institute of Technology (AAiT) in Ethiopia, Nelson Mandela African Institute of Science and Technology (NM-AIST) and Star High School in Tanzania, and IT Education Center in Uganda.
In Tanzania, KAIST students teamed up with NM-AIST students to carry out appropriate technology programs applied with Arduino kits. They plan to use scientific and engineering approaches to address local residents’ living challenges such as developing agricultural water suppliers using sensors measuring water in the soil and oxygen suppliers in the reservoir.
Meanwhile, in Ethiopia and Uganda, student volunteers will be involved in various ICT educational programs for local students. The volunteering corps will also introduce cultural programs including K-Pop dancing for young students there. They will also engage in sports and art classes for students at orphanages in the region.
President Sung-Chul Shin encouraged volunteers at the kick-off ceremony saying, “KAIST students should keep always humility, warmth, and tolerance in mind. I believe our students will exert leadership out there along with knowledge as well as wisdom.”
2018.07.02 View 6996 -
Distinguished Professor Koh Donates His Ho-Am Prize Money
(From left: Distinguished Professor Gou Young Koh and KAIST President Sung-Chul Shin)
Distinguished Professor Gou Young Koh from the Graduate School of Medical Science and Engineering donated one hundred million KRW to KAIST that he received for winning the Ho-Am Prize.
Professor Koh, who is widely renowned for angiogenesis, was appointed as the 2018 laureate of the 28th Ho-Am Prize for demonstrating the effective reduction of tumor progression and metastasis via tumor vessel normalization.
He made the donation to the Graduate School of Medical Science and Engineering, where he conducted his research. “As a basic medical scientist, it is my great honor to receive this prize for the recognition of my research outcome. I will give impetus to research for continuous development,” Professor Koh said.
Professor Koh also received the 5th Asan Award in Medicine in 2012 and the 7th Kyung-Ahm Award in 2011. He was also the awardee of the 17th Wunsch Medical Award. He has donated cash prizes to the school every time he is awarded.
KAIST President Sung-Chul Shin said, “I would like to express my gratitude to the professor for his generous donation to the school. It will be a great help fostering outstanding medical scientists.
Professor Koh received his MD-PhD from the Medical School of Chonbuk National University. After finishing his post-doctoral program at Cornell University and Indiana State University, he was appointed as a professor at Chonbuk National University and POSTECH. Currently, he holds the position of distinguished professor at KAIST and director of the IBS Center for Vascular Research.
2018.06.20 View 5848 -
KAIST Team Reaching Out with Appropriate Technology
(The gold prize winning team of KATT)
The KAIST Appropriate Technology Team (KATT) consisting of international students at KAIST won the gold and silver prizes at ‘The 10th Creative Design Competition for the Other 90 Percent.’
More than 218 students from 50 teams nationwide participated in the competition hosted by the Ministry of Science and ICT last month.
The competition was created to discover appropriate technology and sustainable design items to enhance the quality of life for those with no or few accessible technologies.
A team led by Juan Luis Gonzalez Bello, graduate student from the School of Electrical Engineering received the gold prize for presenting a prosthetic arm. Their artificial arm was highly recognized for its affordability and good manageability. The team said that it cost less than 10 US dollars to construct from materials available in underprivileged regions and was easy to assemble.
Sophomore Hutomo Calvin from the Department of Materials Science & Engineering also worked on the prosthetic arm project with freshmen Bella Godiva, Stephanie Tan, and Koptieuov Yearbola.
Alexandra Tran, senior from the School of Electrical Engineering led the silver prize winning team. Her team developed a portable weather monitor, ‘Breathe Easy’. She worked with Alisher Tortay, senior from the School of Computing, Ashar Alam, senior from the Department of Mechanical Engineering, Bereket Eshete, junior from the School of Computing, and Marthens Hakzimana, sophomore from the Department of Mechanical Engineering.
This weather monitor is a low-cost but efficient air quality monitor. The team said it just cost less than seven US dollars to construct the monitor.KAIST students have now won the gold prize for two consecutive years.
2018.06.19 View 11197 -
Lead-free, Efficient Perovskite for Photovoltaic Cells
(Clockwise from left: Post-doc Researcher Lamjed Debbichi, Master’s Candidate Songju Lee, Professor Min Seok Jang and Professor Hyungjun Kim)
A KAIST research team has proposed a perovskite material, Cs2Au2I6 that serves as a potential active material for highly efficient lead-free thin-film photovoltaic devices. This material is expected to lay the foundation to overcome previously known limitations of perovskite including its stability and toxicity issues.
As strong candidates for next-generation high-efficiency photovoltaic cells, perovskite photovoltaic cells have a maximum photoconversion efficiency of 22%, comparable to high-performance crystalline silicon photovoltaic cells. In addition, perovskite-based cells can be fabricated at low temperatures, thereby bringing about dramatic cost reductions.
However, it has been noted that conventional organic-inorganic hybrid perovskite materials exhibit low stability, eventually degrading their performance and making them unfit for continued use. Moreover, their inclusion of lead has undermined their environmental friendliness.
In light of this, a joint team led by Professor Hyungjun Kim from the KAIST Department of Chemistry and Professor Min Seok Jang from the School of Electrical Engineering has analyzed a previously discovered perovskite material, Cs2Au2I6, consisting of only inorganic substances and investigated its suitability for application in thin-film photovoltaic devices. Theoretical investigations suggests that this new perovskite material is not only as efficient but also more stable and environment friendly compared to the conventional perovskite materials. For this analysis, the team developed multiscale multiphysics simulation frameworks. Atomic-scale first-principle quantum calculations were carried out to study the optical properties of the proposed material, and device-scale electromagnetic simulations were conducted to suggest that the material could indeed serve as a promising photovoltaic substance at the device level.
From this point onward, the research team plans to extend the study in two directions: an empirical study to apply the perovskite material in real-world photovoltaic cells and a theoretical analysis to find the optimal and highly stable material for photovoltaic cells. The team said, “Perovskite materials are highly efficient, but in order to completely replace the conventional solar cells, their stability and toxicity issues must first be resolved.” They added that this research is expected to accelerate related studies in pursuit of high-efficiency, environment-friendly perovskite materials.
This research, led by post-doc researcher Lamjed Debbichi and master’s candidate Songju Lee, was selected as the front cover article of Advanced Materials on March 22.
Figure 1. Cover of Advanced Materials
Figure 2. Schematic of full solar cell device structure
2018.06.08 View 9252 -
Czech Technology Mission with KAIST
Members of the Czech research community visited KAIST to discuss medium to long-term cooperation with KAIST. This visit was hosted by the Fourth Industrial Revolution Intelligence Center (FIRIC).
The community is comprised of people from Czech enterprises and academic institutes that are leading core technologies for the Fourth Industrial Revolution in the fields of AI, robotics, and biotechnology. They had a chance to meet KAIST professors and visit research labs.
Professor Il-Doo Kim from the Department of Materials Science and Engineering, Professor Seongsu Kim from the Department of Mechanical Engineering, and Professor Hyun Uk Kim from the Department of Chemical and Biomolecular Engineering attended the meeting, which took place in the Mechatronics, Systems, and Control Lab under the Vice President for Planning and Budget Soo Hyun Kim and Professor Kyung Soo Kim from the Department of Mechanical Engineering.
Professor Petr Novák from the Technical University of Ostrava said, “It was a meaningful meeting to help understand research trends on industrial robots in Korea.” Professor So Young Kim from FIRIC said, “The Czech research community is strong in basic research where KAIST has outstanding source technology. I hope this visit will open up a path for medium to long-term cooperation on sharing research and technology know-how between the Czech research community and KAIST.”
2018.06.07 View 6906 -
KAIST Ranked the Most Innovative University in Asia 3 Years in a Row
KAIST was ranked the most innovative university in the Asia Pacific region for the third consecutive year. The 2018 Reuter Top 75: Asia’s Most Innovative Universities announced that KAIST topped three of the ten indicators identifying the educational institutions doing the most to advance science, invent new technologies, and power new markets and industries.
KAIST was the top for the number of total patents, patents granted, and commercial impact. KAIST filed 1,000 patents from 2011 to 2016, and earned a 79.8% success rate for patent registrations. In terms of commercial impact, KAIST has almost double the score (59.6) of the University of Tokyo (31.3), who was ranked second. Among top ten most innovative universities in Asia, there were four Korean universities, including Postech, Seoul National University, and Sungkyunkwan University, four Japanese universities, and one each from China and Singapore.
KAIST researchers submitted more patents than any other university on the list, and those patents are frequently cited by outside researchers in their own patents and papers. Those are key criteria in Reuters’ ranking of Asia Pacific’s Most Innovative Universities, which was compiled in partnership with Clarivate Analytics, and is based on proprietary data and an analysis of indicators including patent filings and research paper citations.
2018.06.05 View 6518 -
The Center for Anthropocene Studies (CAS) Opens
KAIST will start Anthropocene research, a convergence field of study, to address issues related to the commencement of human activities that have had scientific, industrial, and economic impacts on the Earth’s ecosystem. The National Research Foundation (NRF) of Korea endorsed the KAIST Center for Anthropocene Studies as its Convergence Research Center project.
Anthropocene refers to a new geological age in which various polluting materials that humans have made during the post-industrial revolution era have made a significant impact on the Earth and the lives of humankind. The studies expand the diverse socio-economic and environmental sectors for responding to climate change, natural disasters, ecological destruction, the polarization of the inequality and wealth, and many others.
The KAIST research group at the center, in collaboration with the Graduate School of Science and Technology Policy, the Graduate School of Culture Technology, the School of Humanities & Social Sciences, the Department of Industrial Design, the School of Electrical Engineering, the Satellite Technology Research Center (SaRTec), and the KAIST Initiative for Disaster Studies will conduct multidisciplinary research to address intriguing challenges with complex but creative approaches incorporating the fields of engineering, socioeconomics, and art.
The group will investigate topics such as▲ surface and marine changes to the Earth by applying satellite data ▲disaster prediction and governance system building through AI modeling ▲sustainable housing, transportation, and lifestyles ▲ engineering and artistic approaches for envisioning a new future for humankind and the Earth.
Professor Buhm Soon Park, who is in charge of the center, said, “This pioneering research work will inspire the re-creation of a new paradigm of convergence studies in science, engineering, humanities, and social science. We will contribute to making the world better by designing new technologies and social policies.
2018.06.05 View 12079 -
Professor YongKeun Park Wins the 2018 Fumio Okano Award
(Professor Park)
Professor YongKeun Park from the Department of Physics won the 2018 Fumio Okano Award in recognition of his contributions to 3D display technology development during the annual conference of the International Society for Optics and Photonics (SPIE) held last month in Orlando, Florida in the US.
The Fumio Okano Best 3D Paper Prize is presented annually in memory of Dr. Fumio Okano, a pioneer and innovator of 3D displays who passed away in 2013, for his contributions to the field of 3D TVs and displays. The award is sponsored by NHK-ES.
Professor Park and his team are developing novel technology for measuring and visualizing 3D images by applying random light scattering. He has published numerous papers on 3D holographic camera technology and 3000x enhanced performance of 3D holographic displays in renowned international journals such as Nature Photonics, Nature Communications, and Science Advances. His technology has drawn international attention from renowned media outlets including Newsweek and Forbes.
He has established two startups to commercialize his technology. Tomocube specializes in 3D imaging microscopes using holotomographic technology and the company exports their products to several countries including the US and Japan. The.Wave.Talk is exploring technology for examining pre-existing bacteria anywhere and anytime.
Professor Park’s innovations have already been recognized in and out of KAIST. In February, he was selected as the KAISTian of the Year for his outstanding research, commercialization, and startups. He was also decorated with the National Science Award in April by the Ministry of Science and ICT and the Hong Jin-Ki Innovation Award later in May by the Yumin Cultural Foundation.
Professor Park said, “3D holography is emerging as a significant technology with growing potential and positive impacts on our daily lives. However, the current technology lags far behind the levels displayed in SF movies. We will do our utmost to reach this level with more commercialization."
2018.05.31 View 10902 -
Fast-Charging Lithium-Oxygen Batteries
(Professor Hye Ryung Byon)
KAIST researchers have paved the way for fast-charging lithium-oxygen batteries.
Professor Hye Ryung Byon from the Department of Chemistry and Professor Yousung Jung from the Graduate School of EEWS led a joint research team to develop lithium-oxygen batteries exhibiting 80% round-trip efficiency even at high charging rates, solving the problem of existing lithium-oxygen batteries which generally showed drastically lower efficiencies when the charge current rate was increased.
This study exploits the size and shape lithium peroxide, a discharge product, which is known to cause the very problems mentioned above. In doing so, the researchers have lowered the overpotential, which is the difference between the thermodynamic reversible potential and the measured potential, and simultaneously improved battery efficiency. Of particular interest is the fact that these high-performance lithium-oxygen batteries can be realized without costly catalysts.
One remarkable property of lithium-oxygen batteries is that they can accommodate three to five times the energy density of lithium-ion batteries commonly used today. Therefore, lithium-oxygen batteries would render longer driving distance to electric vehicles or drones, which operate on the continued use of electrical power.
However, their weakness lies in that, during charge, the lithium peroxide remains undecomposed at low overpotential, resulting in eventually compromising the battery’s overall performance. This is due to the poor ionic and electrical conductivity of lithium peroxide.
To tackle this issue, the researchers could form one-dimensional amorphous lithium peroxide nanostructures through the use of a mesoporous carbon electrode, CMK-3. When compared against non-mesoporous electrodes, CMK-3 showed exceptionally lower overpotential, thereby enhancing the round-trip efficiency of lithium-oxygen batteries.
The amorphous lithium peroxide produced along the electrode has a small volume and a large surface area contacting electrolyte solution, which is presumably endowed with high conductivity to speed up the charging of the lithium-oxygen batteries.
This research underpins the feasibility of overcoming the fundamental limitations of lithium-oxygen batteries even without the addition of expensive catalytic materials, but rather by the re-configuration of the size and shape of the lithium peroxide.
The findings of this research were published in Nature Communications on February 14.
Figure 1. Transmission electron microscopy (TEM) images
Figure 2. Galvanostatic rate capability
Figure 3. Density functional calculation and Bader charge analysis
2018.05.30 View 9956