Kong
-
Dr. Dong-Hyun Cho at KARI Receives the 16th Jeong Hun Cho Award
Dr. Dong-Hyun Cho, a senior researcher at the Korea Aerospace Research Institute (KARI), was honored as the recipient of the 16th Jeong Hun Cho Award. The award recognizes young scientists in the field of aerospace engineering.
Dr. Cho earned his MS and PhD degrees from the KAIST Department of Aerospace Engineering in 2012, and served as a researcher at the Satellite Technology Research Center (SaTReC) at KAIST, before joining the Future Convergence Research Division at KARI. He won this year’s award and received 25 million KRW in prize money.
Jeong Hun Cho, who was a PhD candidate in the Department of Aerospace Engineering at KAIST, passed away in a tragic lab accident in May 2003 and was awarded an honorary doctorate posthumously. His family endowed the award and scholarship in his memory. Since 2005, the scholarship has selected three young scholars every year who specialize in aerospace engineering from Cho’s alma maters of KAIST, Korea University, and Kongju National University High School.
Dr. Dong-Hyun Cho was selected as this year’s awardee in recognition of his studies on the development and operation of KARISMA, a comprehensive software package for space debris collision risk management. Dr. Cho built a terrestrial testbed and produced a model for the development of a space debris elimination algorithm. He published six papers in SCI-level journals and wrote 35 symposium papers in the field of space development. He also applied or registered approximately 40 patents both in Korea and internationally.
The Award Committee also selected three students as scholarship recipients: PhD candidate Yongtae Yun from the Department of Aerospace Engineering at KAIST received 4 million KRW, MS-PhD candidate Haun-Min Lee from the School of Mechanical Engineering at Korea University received 4 million KRW, and Seonju Yim from Kongju National University High School received 3 million KRW.
(END)
2020.05.13 View 12240 -
Scientists Observe the Elusive Kondo Screening Cloud
Scientists ended a 50-year quest by directly observing a quantum phenomenon
An international research group of Professor Heung-Sun Sim has ended a 50-year quest by directly observing a quantum phenomenon known as a Kondo screening cloud. This research, published in Nature on March 11, opens a novel way to engineer spin screening and entanglement. According to the research, the cloud can mediate interactions between distant spins confined in quantum dots, which is a necessary protocol for semiconductor spin-based quantum information processing. This spin-spin interaction mediated by the Kondo cloud is unique since both its strength and sign (two spins favor either parallel or anti-parallel configuration) are electrically tunable, while conventional schemes cannot reverse the sign.
This phenomenon, which is important for many physical phenomena such as dilute magnetic impurities and spin glasses, is essentially a cloud that masks magnetic impurities in a material. It was known to exist but its spatial extension had never been observed, creating controversy over whether such an extension actually existed.
Magnetism arises from a property of electrons known as spin, meaning that they have angular momentum aligned in one of either two directions, conventionally known as up and down. However, due to a phenomenon known as the Kondo effect, the spins of conduction electrons—the electrons that flow freely in a material—become entangled with a localized magnetic impurity, and effectively screen it. The strength of this spin coupling, calibrated as a temperature, is known as the Kondo temperature.
The size of the cloud is another important parameter for a material containing multiple magnetic impurities because the spins in the cloud couple with one another and mediate the coupling between magnetic impurities when the clouds overlap. This happens in various materials such as Kondo lattices, spin glasses, and high temperature superconductors.
Although the Kondo effect for a single magnetic impurity is now a text-book subject in many-body physics, detection of its key object, the Kondo cloud and its length, has remained elusive despite many attempts during the past five decades. Experiments using nuclear magnetic resonance or scanning tunneling microscopy, two common methods for understanding the structure of matter, have either shown no signature of the cloud, or demonstrated a signature only at a very short distance, less than 1 nanometer, so much shorter than the predicted cloud size, which was in the micron range.
In the present study, the authors observed a Kondo screening cloud formed by an impurity defined as a localized electron spin in a quantum dot—a type of “artificial atom”—coupled to quasi-one-dimensional conduction electrons, and then used an interferometer to measure changes in the Kondo temperature, allowing them to investigate the presence of a cloud at the interferometer end.
Essentially, they slightly perturbed the conduction electrons at a location away from the quantum dot using an electrostatic gate. The wave of conducting electrons scattered by this perturbation returned back to the quantum dot and interfered with itself. This is similar to how a wave on a water surface being scattered by a wall forms a stripe pattern. The Kondo cloud is a quantum mechanical object which acts to preserve the wave nature of electrons inside the cloud.
Even though there is no direct electrostatic influence of the perturbation on the quantum dot, this interference modifies the Kondo signature measured by electron conductance through the quantum dot if the perturbation is present inside the cloud. In the study, the researchers found that the length as well as the shape of the cloud is universally scaled by the inverse of the Kondo temperature, and that the cloud’s size and shape were in good agreement with theoretical calculations.
Professor Sim at the Department of Physics proposed the method for detecting the Kondo cloud in the co-research with the RIKEN Center for Emergent Matter Science, the City University of Hong Kong, the University of Tokyo, and Ruhr University Bochum in Germany.
Professor Sim said, “The observed spin cloud is a micrometer-size object that has quantum mechanical wave nature and entanglement. This is why the spin cloud has not been observed despite a long search. It is remarkable in a fundamental and technical point of view that such a large quantum object can now be created, controlled, and detected.
Dr. Michihisa Yamamoto of the RIKEN Center for Emergent Matter Science also said, “It is very satisfying to have been able to obtain real space image of the Kondo cloud, as it is a real breakthrough for understanding various systems containing multiple magnetic impurities. The size of the Kondo cloud in semiconductors was found to be much larger than the typical size of semiconductor devices.”
Publication:
Borzenets et al. (2020) Observation of the Kondo screening cloud. Nature, 579. pp.210-213. Available online at https://doi.org/10.1038/s41586-020-2058-6
Profile:
Heung-Sun Sim, PhD
Professor
hssim@kaist.ac.kr
https://qet.kaist.ac.kr/
Quantum Electron Correlation & Transport Theory Group (QECT Lab)
https://qc.kaist.ac.kr/index.php/group1/
Center for Quantum Coherence In COndensed Matter
Department of Physics
https://www.kaist.ac.kr
Korea Advanced Institute of Science and Technology (KAIST)
Daejeon, Republic of Korea
2020.03.13 View 17700 -
Distinguished Alumni Awardees 2019
The KAIST Alumni Association (KAA) announced four recipients of the Distinguished Alumni Awards for the year 2019. The awards ceremony took place during the New Year Alumni Reception on January 18, 2020 in Seoul.
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. The four distinguished alumni of the year 2019 are listed below.
Myung Joon Kim (School of Computing, M.S., Class of ’78), the President of the Electronics and Telecommunications Research Institute (ETRI), is a renowned expert in software engineering who has served as the president of the Administration Division and ICT Creative Research Laboratory of ETRI. His research and leadership have contributed to fortifying the nation’s IT and electronic industry competitiveness.
Dong Ryeol Shin (School of Electrical Engineering, M.S., Class of ’80), the President of Sungkyunkwan University, is a well-versed expert experienced in both academia and industry. He suggested many creative interdisciplinary educational policies and innovative education programs to lead the way in the Fourth Industrial Revolution, and fostered talents who will go on to be the foundation of national development.
Dong-Myun Lee (School of Electrical Engineering, M.S., Class of ’85, Ph.D., Class of ‘87), the CTO and the head of the Institute of Convergence Technology in KT Corporation, is a creative and practical research innovator. He raised the nation’s competitiveness by leading the development of the high-speed communication network industry and the global expansion of next-generation technology business.
Chang Han Kim (School of Computing, B.S., Class of ’92, M.S., Class of ’97, Ph.D., Class of ’98), the CEO of PUBG Corporation, has contributed greatly to the development of the IT contents industry. He developed PlayerUnknown’s Battlegrounds, a game that has become a global sensation.
Since the establishment of the award in 1992, a total of 103 alumni at home and abroad have been honored as recipients, and brought distinction to the university.
These recipients are playing major roles in society, and some of the notable awardees include: KAIST President Sung-Chul Shin (2010), Samsung Electronics Vice Chairman Ki-Nam Kim (2012), Nexon Chairman Jung-Ju Kim (2007), and the former Science and Technology Advisor to the President Kong-Joo Lee (2005).
The President of KAA and the CEO of Inbody Co Ltd., Ki-Chul Cha, said, “The Distinguished Alumni Awards are honor given to the alumni who contributed to the development of the nation and society, and raised the name of their alma mater.” He added, “We can tell the proud position of KAIST in the global arena just by looking at the accomplishments of the previous awardees.”
(END)
2020.01.20 View 10988 -
Professor Meeyoung Cha, First Young Information Scientist Awardee from KAIST
< Professor Meeyoung Cha (Left) >
Professor Meeyoung Cha from the School of Computing was awarded the fourth Young Information Scientist Award by the Korean Institute of Information Scientists and Engineers (KIISE) last month. Professor Cha is the first from KAIST to win the prize since its establishment under the auspices of the WWW 2014 organizing committee.
The Young Information Scientist Award is awarded to scientists under the age of 40 who have contributed to the development of information science and excelled in research and development in their field.
Professor Cha played a leading role as a young information scientist, having been cited more than 13,000 times in other research papers on fake news detection, lightweight and robust representation of economic scales from satellite imagery, and the development of insomnia detection models.
Reputed as a promising researcher, Professor Cha has been selected as the chief investigator at the Institute for Basic Science (IBS) since January 2019 where she has been operating the Data Science Group under the Center for Mathematical and Computational Sciences.
Professor Cha was also invited as a keynote speaker to the Conference on Empirical Methods in Natural Language Processing (EMNLP), an international academic conference held in Hong Kong in November 2019, where she gave a lecture on “Current Challenges in Computational Social Science” for 1,900 attendees.
(END)
2019.12.31 View 3799 -
Wearable Robot 'WalkON Suit' Off to Cybathlon 2020
Standing upright and walking alone are very simple but noble motions that separate humans from many other creatures. Wearable and prosthetic technologies have emerged to augment human function in locomotion and manipulation. However, advances in wearable robot technology have been especially momentous to Byoung-Wook Kim, a triplegic for 22 years following a devastating car accident.
Kim rejoiced after standing upright and walking again by putting on the ‘WalkON Suit,’ the wearable robot developed by Professor Kyoungchul Kong’s team. Even more, Kim won third prize in the powered exoskeleton race at Cybathlon 2016, an international cyborg Olympics hosted by ETH Zurich.
Now Kim and Professor Kong’s team are all geared up for the Cybathlon Championship 2020. Professor Kong and his startup, Angel Robotics, held a kickoff ceremony for Cybathlon 2020 at KAIST on June 24. The 2020 championship will take place in Switzerland.
Only pilots with complete paralysis of the legs resulting from spinal cord injuries are eligible to participate in the Cybathlon, which takes place every four years. Pilots compete against each other while completing everyday tasks using technical assistance systems in six different disciplines: a brain-computer interface race, a functional electrical stimulation bike race, a powered arm prosthesis race, a powered leg prosthesis race, a powered exoskeleton race, and a powered wheelchair race. The 2016 championship drew 66 pilots from 56 teams representing 25 countries.
In the powered exoskeleton race, pilots complete everyday activities such as getting up from a sofa and overcoming obstacles such as stairs, ramps, or slopes and up to four pilots compete simultaneously on tracks to solve six tasks; and the pilot that solves the most tasks in the least amount of time wins the race.
(Kim, a triplegic for 22 years demonstrates walking and climbing the stairs (below photo) wearing the WalkOn Suit during the media day on June 21 at KAIST.)
Kim, who demonstrated walking and climbing the stairs wearing the WalkON Suit during the media day for the Cybathlon 2020 kickoff ceremony on June 21 at KAIST, said, “I have been confined to a wheelchair for more than 20 years. I am used to it so I feel like the wheelchair is one of my body parts. Actually, I don’t feel any big difficulties in doing everyday tasks in wheelchair. But whenever I face the fact that I will never be able to stand up with my own two legs again, I am so devastated.” He continued, “I still remember the day when I stood up with my own two legs by myself after 22 years. It was beyond description.”
The market for wearable robots, especially for exoskeleton robots, is continuing to grow as the aging population has been a major challenge in almost every advanced country. The global market for these robots expects to see annual growth of 41.2% to 8.3 billion US dollars by 2025. Healthcare wearable robots for the elderly and rehabilitation take up the half of the market share followed by wearable robots for industrial and defense purposes.
Professor Kong from the Department of Mechanical Engineering and his colleagues have developed two wearable robot systems in 2014: The "WalkON Suit" for complete paraplegics and “Angel Suit” for those with partial impairment in walking ability such as the elderly and rehabilitation patients.
Professor Kong said after 15 years of basic research, the team is now able to develop its own distinct technologies. He said their robots are powered by non-resistant precision drives with algorithms recognizing the user’s moving intention. Incorporated with prosthetic devices technology from the Severance Rehabilitation Hospital, their control technology has led to the production of a customizable robot suit optimized for each user’s physical condition.
The WalkON Suit, which boasts a maximum force of 250 Nm and maximum rotation speed of 45 RPM, gives the user high-energy efficiency modeled after the physiology of the human leg. It allows users to walk on flat ground and down stairs, climb up and down inclines, and sit and lie down. Currently the battery lasts five to six hours for locomotion and the approximate 25 kg of robot weight still remains a technical challenge to upgrade.
Professor Kong’s team has grafted AR glass technology into the WalkOn Suit that one of his pilots put on for the torch relay of the PyongChang Paralympics in 2018. His team is now upgrading the WalkON Suit 4.0 for next year’s competition. Severance Rehabilitation Hospital will help the seven pilots with their training.
Professor Kong said his goal is to make robots that can make people with disabilities much more independent. He stressed, “Wearable robots should be designed for each single user. We provide a very good graphical user interface so that we can design, check, and also verify our optimized design for users’ best performance.”
(Seven pilots and Professor Kong (fifth from left in second row) pose with guests who joined the Cybathlon 2020 kickoff ceremony. President Shin (fifth from right) made a congratulatory remarks during the ceremony.)
2019.06.25 View 42474 -
Professor Park at UPC-Barcelona Tech Receives Jeong Hun Cho Award
Professor Hyuk Park was honored to be the recipient of the Jeong Hun Cho Award which was presented at the Universitat Politècnica de Catalunya Barcelona Tech. The award recognizes young scientists in the field of aerospace engineering.
Professor Park, a graduate of KAIST’s Department of Mechanical Engineering in 2001, earned his MS and PhD at the Gwangju Institute of Science and Technology, and works at the Castelldefels School of Telecommunications and Aerospace Engineering at UPC-Barcelona Tech. He won this year’s award, which honors former PhD candidate Jeong Hun Cho at the Aerospace Engineering Department who died in a lab accident in 2003. Professor Park also received 25 million KRW prize money. Cho’s family endowed the award and scholarship in his memory. Since 2005, the scholarship has selected three young scholars every year who specialize in aerospace engineering from Cho’s alma maters of KAIST, Korea University, and Kongju National University High School.
Professor Park was selected as this year’s awardee in recognition of his studies of synthetic-aperture radar (SAR) satellite radiometer system, remote sensing radio frequency interference reduction system development, and 3CAT series research.
The Award Committee also chose three students for scholarships: PhD candidate Sang-Woo Chung from the Department of Aerospace Engineering at KAIST with 4 million KRW, PhD candidate Eun-Hee Kang from the School of Mechanical Engineering at Korea University with 4 million KRW, and Chan-Ho Song from Kongju National University High School with 3 million KRW.
2019.05.14 View 9135 -
Team KAT Wins the Autonomous Car Challenge
(Team KAT receiving the Presidential Award)
A KAIST team won the 2018 International Autonomous Car Challenge for University Students held in Daegu on November 2.
Professor Seung-Hyun Kong from the ChoChunShik Graduate School of Green Transportation and his team participated in this contest with the team named KAT (KAIST Autonomous Technologies). The team received the Presidential Award with a fifty million won cash prize and an opportunity for a field trip abroad.
The competition was conducted on actual roads with Connected Autonomous Vehicles (CAV), which incorporate autonomous driving technologies and vehicle-to-everything (V2X) communication system.
In this contest, the autonomous vehicles were given a mission to pick up passengers or parcels. Through the V2X communication, the contest gave current location of the passengers or parcels, their destination, and service profitability according to distance and level of service difficulty.
The participating vehicles had to be equipped very accurate and robust navigation system since they had to drive on narrow roads as well as go through tunnels where GPS was not available. Moreover, they had to use camera-based recognition technology that was invulnerable to backlight as the contest was in the late afternoon.
The contest scored the mission in the following way: the vehicles get points if they pick up passengers and safely drop them off at their destination; on the other hand, points are deducted when they violate lanes or traffic lights. It will be a major black mark if a participant sitting in the driver’s seat needs to get involved in driving due to a technical issue.
Youngbo Shim of KAT said, “We believe that we got major points for technical superiority in autonomous driving and our algorithm for passenger selection.”
This contest, hosted by Ministry of Trade, Industry and Energy, was the first international competition for autonomous driving on actual roads. A total of nine teams participated in the final contest, four domestic teams and five teams allied with overseas universities such as Tsinghua University, Waseda University, and Nanyang Technological University.
Professor Kong said, “There is still a long way to go for fully autonomous vehicles that drive flexibly under congested traffic conditions. However, we will continue to our research in order to achieve high-quality autonomous driving technology.”
(Team KAT getting ready for the challenge)
2018.11.06 View 13689 -
Yoon Ki Hong Named 2018 Jeong Hun Cho Awardee
(From left: PhD candidate Seungkwan Baek from the Department of Aerospace Engineering, Dr. Yoon Ki Hong from ADD, PhD candidate Wonhee Choi from the School of Mechanical Engineering at Korea University, and Jaehun Lee from Kongju National University High School)
Dr. Yoon Ki Hong from the Agency of Defense Development (ADD) was named the 2018 recipient of the Jong-Hoon Cho Award. The award recognizes outstanding young scientists in the field of aerospace engineering annually. The recipient of this award receives a 25 million KRW prize.
The Award Committee said that Dr. Hong has achieved outstanding work in the field of aerospace engineering. In particular, he conducted research on designing an air heating device which is the crucial component for ground experimental equipment. It is required for testing and evaluating supersonic vehicles’ structural strength tests using technology cannot be imported. In cooperation with his colleagues, he succeeded in developing an air heating device, a feat that has only been accomplished by developed countries. He also verified its operational performance.
Moreover, he received the best paper award from Korean Federation of Science and Minister of Defense Acquisition Program Administration’s Prize.
The award was endowed by the family of the late PhD candidate Jeong Hun Cho, who died in a rocket lab accident in the Department of Aerospace Engineering in 2003. Cho was posthumously conferred an honorary doctorate degree.
In Cho’s memory, his father established the ‘Jeong Hun Cho Award and Scholarship’. Since 2005, the scholarship annually selects three young scholars specializing in aerospace engineering from Cho’s alma maters of KAIST, Korea University, and Kongju National University High School.
In addition to Dr. Hong, the Award Committee chose three students for scholarships: PhD candidate Seungkwan Baek from the Department of Aerospace Engineering, PhD candidate Wonhee Choi from the School of Mechanical Engineering at Korea University, and Jaehun Lee from Kongju National University High School.
2018.05.11 View 11207 -
KAIST Develops IoT Platform for Food Safety
A research team led by the KAIST Auto-ID Labs developed a GS1 international standard-based IoTs infrastructure platform dubbed Oliot (Open Language of Internet of Things). This platform will be applied to Wanju Local Food, the nation’s largest cooperative, and will be in operation from April 5.
A total of eleven organizations participated in the development of Oliot, with KAIST as the center. This consortium is based on the GS1 international standard-based Oliot platform, which allows collecting and sharing data along the entire process of agrifood from production to processing, distribution, and consumption. It aims at increasing farm incomes and establishing a global ecosystem of domestic agriculture and stockbreeding that provides safe food.
Wanju Local Food is now the world’s first local food co-op with a traceability system from the initial stage of production planning to end sales based on GS1 international standards, which will ensure food safety.
KAIST has been sharing Oliot data in order to apply it to industries around the world. As of April 2018, approximately 900 enterprises and developers from more than 100 countries have downloaded it.
Professor Daeyoung Kim from the School of Computing, who is also Research Director of Auto-ID Labs said, “We are planning to disseminate Oliot to local food cooperatives throughout the nation. We will also cooperate with other countries, like China, Holland, and Hong Kong to create a better ecosystem for the global food industry.
“We are currently collaborating with related business to converge Oliot with AI or blockchain technology that can be applied to various services, such as healthcare and smart factories. Its tangible outcome will be revealed soon,” he added.
Auto-ID Labs are a global research consortium of six academic institutions that research and develop new technologies for advancing global commerce, partnering with GS1 (Global Standard 1), a non-profit organization that established standards for global commerce such as introducing barcodes to the retail industry. The Auto-ID Labs include MIT, University of Cambridge, Keio University, Fudan University, ETH Zurich/University of St. Gallen, and KAIST.
The consortium was supported by the Ministry of Science and ICT as well as the Institute for Information and Communications Technology Promotion for three years from 2015.
The launching of Oliot at Wanju Local Food will be held on April 5.
2018.04.03 View 10679 -
KAIST to Host the THE Innovation & Impact Summit in 2019
KAIST and Times Higher Education (THE) agreed to co-host the THE Innovation & Impact Summit at KAIST from April 1 to 3, 2019.
Global leaders from higher education, government, and industry will gather at KAIST to discuss how universities can better innovate for creating a greater impact.
(from left: THE Managing Director Trevor Barratt and KAIST President Sung-Chul Shin)
President Sung-Chul Shin and Trevor Barratt, managing director at the THE, signed an agreement to host the 2019 THE Innovation & Impact Summit at KAIST next April. The agreement was signed on February 6 during the THE Asia Universities Summit held at SUSTech in Shenzhen in China. Phil Baty, editorial director at the THE was also present during the agreement.
By hosting the 2019 THE Innovation & Impact Summit, KAIST has a chance to introduce its innovative research and performance and its educational environment and startup ecosystem to the world. Having educational and industrial leaders meet at KAIST will add more power to the global status and capacity of KAIST.
The THE Innovation & Impact Summit, first held in 2017, is one in the seven presidential summit series held by THE. During the second summit at KAIST, THE will launch their world university innovation rankings for the first time.
As innovation at universities and its impact have been a crucial indicator in building an institutional brand and reputation, leading universities are gearing up to encourage startups and entrepreneurship education. Even more, innovation at universities is emerging as one of the growth engines of economies.
The innovation indicators of KAIST have been highly recognized by many global ranking institutions in terms of the volume of patents and the patents-to-article citation impact. Thomson Reuters has recognized KAIST for two consecutive years as the most innovative university in Asia, and sixth in the world.
President Shin has high expectations for the hosting of the Innovation & Impact Summit at KAIST. He explained, “Innovation makes up the DNA of KAIST and it has been our institutional mission from the start in 1971. KAIST was commissioned to make innovation for industrialization and economic development through education and research. I do not see any university more suitable than KAIST to host this innovation summit. I hope the summit at KAIST will serve as a global platform to provide very creative ideas for making innovation and collaboration among the leading universities for all the participants.”
Meanwhile, at the THE Asia Universities Summit in Shenzhen, how to respond to the implications of the Fourth Industrial Revolution was the key agenda piercing the two-day sessions.
As a panelist, President Shin shared his experiences on innovative strategies viable for spearheading university reform for the Fourth Industrial Revolution, along with Vice-Chancellor of the University of Sheffield Sir Keith Burnett, President of Monash University Margaret Gardner, and President of Hong Kong Polytechnic University President Timothy W. Tong. He said that universities should foster young talents by equipping them with creativity, collaboration, and convergent minds. To swiftly respond to the new industrial environment, President Shin said that universities should remove the high barriers between departments and establish cross- and inter-disciplinary education systems, convergence research and technology commercialization.
2018.02.06 View 10347 -
Highly Sensitive and Fast Indoor GNSS Signal Acquisition Technology
(Professor Seung-Hyun Kong (right) and Research Fellow Tae-Sun Kim)
A research team led by Professor Seung-Hyun Kong at the Cho Chun Shik Graduate School of Green Transportation, KAIST, developed high-speed, high-sensitivity Global Navigation Satellite System (GNSS) signal acquisition (search and detection) technology that can produce GNSS positioning fixes indoors.
Using the team’s new technology, GNSS signals will be sufficient to identify locations anywhere in the world, both indoors and outdoors. This new research finding was published in the international journal IEEE Signal Processing Magazine (IEEE SPM) this September.
Global Positioning System (GPS) developed by the U.S. Department of Defense in the 1990s is the most widely-used satellite-based navigation system, and GNSS is a terminology to indicate conventional satellite based navigation systems, such as GPS and Russian GLONASS, as well as new satellite-based navigation systems under development, such as European GALILEO, Chinese COMPASS, and other regional satellite-based navigation systems.
In general, GNSS signals are transmitted all over the globe from 20,000 km above the Earth and thus a GNSS signal received by a small antennae in an outdoor environment has weak signal power. In addition, GNSS signals penetrating building walls become extremely weak so the signal can be less than 1/1000th of the signal power received outside.
Using conventional acquisition techniques including the frequency-domain correlation technique to acquire an extremely weak GNSS signal causes the computational cost to increase by over a million times and the processing time for acquisition also increases tremendously. Because of this, indoor measurement techniques using GNSS signals were considered practically impossible for the last 20 years.
To resolve such limitations, the research team developed a Synthesized Doppler-frequency Hypothesis Testing (SDHT) technique to dramatically reduce the acquisition time and computational load for extremely weak GNSS signals indoors.
In general, GNSS signal acquisition is a search process in which the instantaneous accurate code phase and Doppler frequency of the incoming GNSS signal are identified. However, the number of Doppler frequency hypotheses grows proportionally to the coherent correlation time that should be necessarily increased to detect weak signals. In practice, the coherent correlation time should be more than 1000 times longer for extremely weak GNSS signals so the number of Doppler frequency hypotheses is greater than 20,000. On the other hand, the SDHT algorithm indirectly tests the Doppler frequency hypothesis utilizing the coherent correlation results of neighboring hypotheses.
Therefore, using SDHT, only around 20 hypotheses are tested using conventional correlation techniques and the remaining 19,980 hypotheses are calculated with simple mathematical operations. As a result, SDHT achieves a huge computational cost reduction (by about 1000 times) and is 800 times faster for signal acquisition compared to conventional techniques. This means only about 15 seconds is required to detect extremely weak GNSS signals in buildings using a personal computer.
The team predicts further studies for strengthening SDHT technology and developing positioning systems robust enough to multipath in indoor environments will allow indoor GNSS measurements within several seconds inside most buildings using GNSS alone.
Professor Kong said, “This development made us the leader in indoor GNSS positioning technology in the world.” He continued, “We hope to commercialize indoor GNSS systems to create a new market.” The research team is currently registering a patent in Korea and applying for patents overseas, as well as planning to commercialize the technology with the help of the Institute for Startup KAIST.
(Figure1. Positioning Results for the GPS Indoor Positioning System using SDHT Technology)
2017.11.02 View 7601 -
Unlocking the Keys to Parkinson's Disease
A KAIST research team has identified a new mechanism that causes the hallmark symptoms of Parkinson’s disease, namely tremors, rigidity, and loss of voluntary movement.
The discovery, made in collaboration with Nanyang Technological University in Singapore, presents a new perspective to three decades of conventional wisdom in Parkinson’s disease research. It also opens up new avenues that can help alleviate the motor problems suffered by patients of the disease, which reportedly number more than 10 million worldwide. The research was published in Neuron on August 30.
The research team was led by Professor Daesoo Kim from the Department of Biological Sciences at KAIST and Professor George Augustine from the Lee Kong Chian School of Medicine at NTU. Dr. Jeongjin Kim, a former postdoctoral fellow at KAIST who now works at the Korea Institute of Science and Technology (KIST), is the lead author.
It is known that Parkinson’s disease is caused by a lack of dopamine, a chemical in the brain that transmits neural signals. However, it remains unknown how the disease causes the motor
Smooth, voluntary movements, such as reaching for a cup of coffee, are controlled by the basal ganglia, which issue instructions via neurons (nerve cells that process and transmit information in the brain) in the thalamus to the cortex. These instructions come in two types: one that triggers a response (excitatory signals) and the other that suppresses a response (inhibitory signals). Proper balance between the two controls movement.
A low level of dopamine causes the basal ganglia to severely inhibit target neurons in the thalamus, called an inhibition. Scientists have long assumed that this stronger inhibition causes the motor problems of Parkinson’s disease patients.
To test this assumption, the research team used optogenetic technology in an animal model to study the effects of this increased inhibition of the thalamus and ultimately movement. Optogenetics is the use of light to control the activity of specific types of neurons within the brain.
They found that when signals from the basal ganglia are more strongly activated by light, the target neurons in the thalamus paradoxically became hyperactive. Called rebound excitation, this hyperactivity produced abnormal muscular stiffness and tremor. Such motor problems are very similar to the symptoms of Parkinson’s disease patients. When this hyperactivity of thalamic neurons is suppressed by light, mice show normal movments without Parkinson’s disease symptoms. Reducing the levels of activity back to normal caused the motor symptoms to stop, proving that the hyperactivity caused the motor problems experienced by Parkinson’s disease patients.
Professor Kim at KAIST said, “This study overturns three decades of consensus on the provenance of Parkinsonian symptoms.” The lead author, Dr Jeongjin Kim said, “The therapeutic implications of this study for the treatment of Parkinsonian symptoms are profound. It may soon become possible to remedy movement disorders without using L-DOPA, a pre-cursor to dopamine.”
Professor Augustine at NTU added, “Our findings are a breakthrough, both for understanding how the brain normally controls the movement of our body and how this control goes awry during Parkinson’s disease and related dopamine-deficiency disorders.”
The study took five years to complete, and includes researchers from the Department of Bio & Brain Engineering at KAIST.
The research team will move forward by investigating how hyperactivity in neurons in the thalamus leads to abnormal movement, as well as developing therapeutic strategies for the disease by targeting this neural mechanism.
Figure abstract: Inhibitory inputs from the basal ganglia inhibit thalamic neurons (upper). In low-dopamine states, like PD, rebound firing follows inhibition and causes movement disorders (middle). The inhibition of rebound firing alleviates PD-like symptoms in a mouse model of PD.
2017.09.22 View 11293