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Short Wavelength, Ultra-High Speed Quantum Light Source based on Quantum Dot Developed
Professor Yong Hoon, Cho (Department of Physics) and his research team synthesized an obelisk nanostructure and successfully formed a single semiconductor quantum exhibiting high reliability to realize an ultra-high speed, highly efficient, release of quantum dots.
The result of the research effort was published in the July 5th online edition of Scientific Reports published by Nature.
Semiconductor Quantum Dots restrict electrons within a cubic boundary of few nanometers thereby exhibiting similar properties to an atom with discontinuous energy levels. Exploitation of this characteristic makes possible the development of quantum light source, critical for next generation quantum information communication and quantum encryption.
High operational temperatures, stability, rapid photon release, electric current capability, and other advantages are reasons why semiconductor quantum dots are regarded as next generation core technology.
However conventional, spontaneously formed quantum dots are densely packed in a planar structure rendering the analysis of a single quantum dot difficult and result in the poor efficiency of photon release. In addition, the internal electromagnetic effect which is caused by inter-planar stress results in low internal quantum efficiency due to the difficulty in electron-hole recombination.
Professor Cho’s research team synthesized an obelisk shaped nanostructure using nitrides that emit short wavelengths of light. The activation layer was grown on the tip of the nanostructure and the team succeeded in placing a single quantum dot on the nano-tip. The team was therefore able to confirm the ultra-high speed single photon characteristics which occur at low energy levels.
Use of unique nanostructures makes synthesis of single atomic structures without processes like patterning while enabling the release of light emitted by the quantum dot.
Using this unique method the team showed the increase in internal quantum efficiency. The electromagnetic forces apparent in thin films no longer affects the quantum dot greatly due to the obelisk structure’s reduced inter planar stress.
The newly developed quantum light source emits visible light (400nm range) and not the conventional infrared light. This characteristic makes possible it use in communication in free space and enables use of highly efficient, visible range photon detector.
Professor Cho commented that “the developed method makes quantum dot growth much easier making single photon synthesis much faster to contribute to the development of practical quantum light source.” And that “the characteristics of the obelisk nanostructure enable the easy detachment from and attachment to other substrates enabling its use in producing single chip quantum light source.”
The research was conducted under the supervision of Professor Cho. The researchers werey Jae Hyung, Kim (first author) and Yong Ho, Ko (second author), both Ph.D. candidates at KAIST. The Ministry of Science, ICT and Future Planning, the National Research Foundation, and WCU Program provided support to the research effort.
2013.08.23 View 8742 -
KAIST unveils foldable micro electric car, Armadillo-T
The small and light electric car completely folds in half when parking, making it a perfect fit for public or private transportation in an urban environment.
Looking for a parking space for hours at a busy shopping mall or being stuck on roads jammed with cars releasing large amounts of carbon dioxide are all-too-familiar scenes for city dwellers.
A group of researchers at the Korea Advanced Institute of Science and Technology (KAIST) recently developed a possible solution to such problems: a foldable, compact electric vehicle that can be utilized either as a personal car or part of the public transit system to connect major transportation routes within a city.
In-Soo Suh, associate professor of the Graduate School for Green Transportation at KAIST, and his research team introduced a prototype micro electric car called "Armadillo-T," whose design is based on a native animal of South America, the armadillo, a placental mammal with a leathery armor shell.
The research team imitated the animal"s distinctive protection characteristic of rolling up into a ball when facing with threat from predators. Just as armadillos hide themselves inside the shell, Armadillo-T tucks its rear body away, shrinking its original size of 2.8 meters (110 inches) down to almost half, 1.65 meters (65 inches), when folding.
Armadillo-T is a four-wheel-drive, all-electric car with two seats and four in-wheel motors. Since the motors are installed inside the wheels, and the 13.6 kWh capacity of lithium-ion battery pack is housed on the front side, the battery and motors do not have to change their positions when the car folds. This not only optimizes the energy efficiency but also provides stability and ample room to drivers and passengers.
Once folded, the small and light (weighs 450 kg) electric vehicle takes up only one-third of a 5-meter parking space, the standard parking size in Korea, allowing three of its kind to be parked. With a smartphone-interfaced remote control on the wheels, the vehicle can turn 360 degrees, enhancing drivers" convenience to park the car, even in an odd space in a parking lot, the corner of a building, for example.
Professor In-Soo Suh said, "I expect that people living in cities will eventually shift their preferences from bulky, petro-engine cars to smaller and lighter electric cars. Armadillo-T can be one of the alternatives city drivers can opt for. Particularly, this car is ideal for urban travels, including car-sharing and transit transfer, to offer major transportation links in a city. In addition to the urban application, local near-distance travels such as tourist zones or large buildings can be another example of application."
The concept car has loads of smart features on board, too: the cameras installed inside the car eliminate the need for side mirrors and increase the driver"s ability to see the car"s right and left side, thereby reducing blind spots. With a smartphone, the driver can control Armadillo-T and enable remote folding control. The car has a maximum speed of 60 km/h, and with a ten-minute fast charge, it can run up to 100 km.
Professor Suh explained that the concept of Armadillo-T was originally initiated in 2011 as he focused his research interest on the sub-A segment of personal mobility vehicles (PMVs), which are smaller and lighter than the current compact cars, as a new personalized transport mode.
"In coming years, we will see more mega-size cities established and face more serious environmental problems. Throughout the world, the aging population is rapidly growing as well. To cope with climate, energy, and limited petroleum resources, we really need to think outside the box, once again, to find more convenient and eco-friendly transportation, just as the Ford Model T did in the early 1920s. A further level of R&D, technical standards, and regulatory reviews are required to have these types of micro vehicles or PMVs on the market through test-bed evaluations, but we believe that Armadillo-T is an icon toward the future transport system with technology innovation."
The research project has been supported by the Korean government, the Ministry of Land, Infrastructure and Transport and the Korea Agency for Infrastructure Technology Advancement, since December 2012.Youtube Link: http://www.youtube.com/watch?v=8DoZH7Y-sR0
2013.08.21 View 15527 -
Chemistry World: Interview with Professor Cafer Yavuz of EEWS Graduate School
Professor Cafer Yavuz of the Graduate School of EEWS (energy, environment, water, and sustainability) at KAIST had an interview with the Chemistry World, the print and online magazine issued by the Royal Society of Chemistry, the largest organization in Europe for advancing the chemical sciences. The link below is the article published by the magazine:
http://www.rsc.org/chemistryworld/2013/08/interview-cafer-yavuz-carbon-dioxide-capture
2013.08.07 View 8252
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KAIST's wireless Online Electric Vehicle (OLEV) runs inner city roads
For the first time anywhere, electric buses provide public transportation services and are recharged right from the road.
The Online Electric Vehicle (OLEV), developed by the Korea Advanced Institute of Science and Technology (KAIST), is an electric vehicle that can be charged while stationary or driving, thus removing the need to stop at a charging station. Likewise, an OLEV tram does not require pantographs to feed power from electric wires strung above the tram route.
Following the development and operation of commercialized OLEV trams (at an amusement park in Seoul) and shuttle buses (at KAIST campus), respectively, the City of Gumi in South Korea, beginning on August 6th, is providing its citizens with OLEV public transportation services.
Two OLEV buses will run an inner city route between Gumi Train Station and In-dong district, for a total of 24 km roundtrip. The bus will receive 20 kHz and 100 kW (136 horsepower) electricity at an 85% maximum power transmission efficiency rate while maintaining a 17cm air gap between the underbody of the vehicle and the road surface.
OLEV is a groundbreaking technology that accelerates the development of purely electric vehicles as a viable option for future transportation systems, be they personal vehicles or public transit. This is accomplished by solving technological issues that limit the commercialization of electric vehicles such as price, weight, volume, driving distance, and lack of charging infrastructure.
OLEV receives power wirelessly through the application of the “Shaped Magnetic Field in Resonance (SMFIR)” technology. SMFIR is a new technology introduced by KAIST that enables electric vehicles to transfer electricity wirelessly from the road surface while moving. Power comes from the electrical cables buried under the surface of the road, creating magnetic fields. There is a receiving device installed on the underbody of the OLEV that converts these fields into electricity. The length of power strips installed under the road is generally 5%-15% of the entire road, requiring only a few sections of the road to be rebuilt with the embedded cables.
OLEV has a small battery (one-third of the size of the battery equipped with a regular electric car). The vehicle complies with the international electromagnetic fields (EMF) standards of 62.5 mG, within the margin of safety level necessary for human health. The road has a smart function as well, to distinguish OLEV buses from regular cars—the segment technology is employed to control the power supply by switching on the power strip when OLEV buses pass along, but switching it off for other vehicles, thereby preventing EMF exposure and standby power consumption. As of today, the SMFIR technology supplies 60 kHz and 180 kW of power remotely to transport vehicles at a stable, constant rate.
Dong-Ho Cho, a professor of the electrical engineering and the director of the Center for Wireless Power Transfer Technology Business Development at KAIST, said:
“It’s quite remarkable that we succeeded with the OLEV project so that buses are offering public transportation services to passengers. This is certainly a turning point for OLEV to become more commercialized and widely accepted for mass transportation in our daily living.”
After the successful operation of the two OLEV buses by the end of this year, Gumi City plans to provide ten more such buses by 2015.
2013.08.07 View 25714 -
Technology Developed to Control Light Scattering Using Holography
Published on May 29th Nature Scientific Reports online
Recently, a popular article demonstrated that an opaque glass becomes transparent as transparent tape is applied to the glass. The scientific principle is that light is less scattered as the rough surface of the opaque glass is filled by transparent tape, thereby making things behind the opaque glass look clearer.
Professor Yong-Keun Park from KAIST’s Department of Physics, in a joint research with MIT Spectroscopy Lab, has developed a technology to easily control light scattering using holography. Their results are published on Nature’s Scientific Reports May 29th online edition.
This technology allows us to see things behind visual obstructions such as cloud and smoke, or even human skin that is highly scattering, optically thick materials. The research team applied the holography technology that records both the direction and intensity of light, and controlled light scattering of obstacles lied between an observer and a target image. The team was able to retrieve the original image by recording the information of scattered light and reflecting the light precisely to the other side.This phenomenon is known as “phase conjugation” in physics. Professor Park’s team applied phase conjugation and digital holography to observe two-dimensional image behind a highly scattering wall. “This technology will be utilized in many fields of physics, optics, nanotechnology, medical science, and even military science,” said Professor Park. “This is different from what is commonly known as penetrating camera or invisible clothes.” He nevertheless drew the line at over-interpreting the technology, “Currently, the significance is on the development of the technology itself that allows us to accurately control the scattering of light."
Figure I. Observed Images
Figure II. Light Scattering Control
2013.07.19 View 9046 -
Joint Research Center on EEWS with Hyundai Heavy Industries Plans to Open
The research center will conduct collaborative R&D projects on energy, environment, water, and sustainability for the next five years.Hyundai Heavy Industries (HHI), the world’s largest shipbuilding company, signed an MOU with KAIST for future business development and joint research collaboration.
KAIST and HHI signed an MOU as an agreement to establish the “HHI-KAIST EEWS Research Center (HK Research Center) on June 21st.”
The major mission of the HK Research Center is to build a strong base for creating future businesses through developing fundamental, core technology in the field of EEWS and designing business models based on the new technology.
Toward this goal, HHI will sponsor the R&D budget and operation expenses of the research center for the next five years.
Prior to the signing of the MOU, a delegation from HHI, led by the Vice President, Mr. Si-Young Hwang, visited the Office of EEWS Initiative at KAIST and held a workshop. During the workshop, HHI and KAIST agreed to collaborate in fields such as LNG-propelled ships, solar power generation, energy storage, fuel cells, and CO2 capture.
KAIST has run a EEWS graduate program that receives government grants over the last five years, with a research emphasis on energy, environment, water, and sustainability, which are crucial issues to humankind in the 21st century. The EEWS program achieved 24 core technological developments and educates more than 200 masters- and PhD-degree students annually.
The EEWS program also emphasizes commercializing its research outcomes. Through the annual Business Planning Competition and Investment Drive, there have been eight new companies founded by alumni and professors over the last five years of the program. The HK Research Center will be an excellent foundation for future education and research in EEWS.
Professor Jae-Kyu Lee, the head of the HK Research Center and the director of the EEWS Initiative, said, “This event is a benchmarking example of Industry-KAIST collaboration. We hope that the HK Research Center will be a place for disruptive innovations to translate into creative business opportunities.”
MOU signed for Hyundai Heavy Industries-KAIST EEWS Research Center
2013.07.15 View 9118 -
Prof. Song Chong received the IEEE William R. Bennett Prize Paper Award
The IEEE (Institute of Electrical and Electronics Engineers) Communications Society (ComSoc), a renowned global network of professionals with a common interest in advancing communications technologies, has announced the winner of the 2013 William R. Bennett Prize in the field of communications networking. The prize was given to a Korean research team led by Song Chong, Professor of Electrical Engineering at KAIST and Injong Rhee, Professor of Computer Science at North Carolina State University. In addition, Dr. Minsu Shin, Dr. Seongik Hong, and Dr. Seong Joon Kim of Samsung Electronics Co., Ltd. as well as Professor Kyunghan Lee from Ulsan National Institute of Science and Technology were recognized for their contribution.
The William R. Bennett Prize for communications networking has been awarded each year since 1994 in recognition of the best paper published in any journal financially sponsored or co-sponsored by ComSoc in the previous three calendar years. Only one paper per year is selected based on its quality, originality, scientific citation index, and peer reviews. Among the previous award winners are Robert Gallager of MIT, and Steven Low of the California Institute of Technology, and Kang G. Shin of the University of Michigan.
The Korean research team’s paper, On the Levy-Walk Nature of Human Mobility, was published in the June 2011 issue of IEEE/ACM Transactions on Networking, a bimonthly journal co-sponsored by the IEEE ComSoc, the IEEE Computer Society, and the Association for Computing Machinery (ACM) with its Special Interest Group on Data Communications (SIGCOMM).
In the paper, the research team proposed a new statistical model to effectively analyze the pattern of individual human mobility in daily life. The team handed out GPS (global positioning system) devices to 100 participants residing in five different university campuses in Korea and the US and collected data on their movements for 226 days. The mobility pattern obtained from the experiment predicted accurately how the participants actually moved around during their routines. Since publication, the paper has been cited by other papers approximately 350 times.
The team’s research results will apply to many fields such as the prevention and control of epidemics, the design of efficient communications networks, and the development of urban and transportation system.
The research team received the award on June 10th at the 2013 IEEE International Conference on Communications (ICC) held in Budapest, Hungary, from June 9-13, 2013.
Professor Song Chong
2013.07.06 View 14088 -
Thinking Out of the Box: KAIST Silicon Valley Innovation Platform
KAIST established a liaison office in San Jose, California, to support the entrepreneurship of KAIST graduates, students, and faculty who aspire to transform their innovative ideas into business.
The office, KAIST Silicon Valley Innovation Platform (SVIP), is located within the Korea Trade-Investment Promotion Agency (KOTRA) IT Center on North First Street in San Jose.
SVIP collects information and analyzes trends on emerging technologies; provides various educational programs on entrepreneurship and technology translation; offers opportunities to prospective entrepreneurs to engage with industry and research and government organizations; and assists Korean startups in accessing the US and North American market.
President Steve Kang attended the opening ceremony of the office on June 14th and encouraged KAIST alumni living in the US to share their ideas and technology innovations and transform them into business opportunities.
For more information, please contact Professor Soung-Hie Kim (seekim@business.kaist.ac.kr) from the Graduate School of Information and Media Management, KAIST.
2013.07.04 View 9032 -
Technology for Non-Breaking Smartphone Display Developed
High-strength plastic display has been developed by applying a glass-fiber fabric.
“Will bring about innovation to the field by replacing glass substrates”
It is now possible to manufacture non-breaking smartphone display. Heavy glass substrates of large-screen televisions will be replaced with light plastic films.
Professor Choon Sup Yoon from KAIST’s Department of Physics and KAIST Institute for Information Technology Convergence has developed the technology for high-strength plastic substrates to replace glass displays.
The plastic substrate created by Professor Yoon and his research team have greatly enhanced needed properties of heat resistance, transparency, flexibility, inner chemical capability, and tensile strength. Although the material retains flexibility as a native advantage of plastic film, its tensile strength is three times greater than that of normal glass, which is a degree similar to tempered glass. In addition, Professor Yoon’s substrate is as colorless and transparent as glass and resists heat up to 450℃, while its thermal expansivity is only 10% to 20% of existing plastics.
Glass substrates are currently used in practically every display such as mobile phone screens, televisions, and computer monitors for having smooth surface and satisfying basic conditions for display substrates. However, as glass substrates are heavy and easily broken, researchers studied colorless and transparent plastic polyimide films to replace glass substrates for their excellent thermal and chemical stability.
Nonetheless, colorless and transparent polyimide films do not have sufficient heat resistance and mechanical solidity. To resolve this problem, polyimide films are impregnated with glass-fiber fabrics, but it was far from commercialization as the impregnation exacerbates the roughness of surface and light transmittance. The roughness of the surface increases as the solvent evaporates in the impregnation process, resulting in surface roughness of around 0.4μm. The downturn in light transmittance is due to light scattering effect by the discording refractive index of polyimide film and glass-fiber fabric.
Professor Yoon’s research team resolved these issues by tuning the refractive indices of transparent polyimide film and glass-fiber fabric up to four decimal places, and by developing the technology of flattening the film’s surface roughness to a few nanometers. As a result, the research team achieved heat expansivity of 11ppm/℃, surface roughness of 0.9nm, tensile strength of 250MPa, bending curvature radius of 2mm, and light transmittance at 90% with a 110μm-thick glass-fiber fabric impregnated transparent polyimide film substrate.
“The developed substrate can not only replace the traditional glass substrate but also be applied as flexible display substrate,” said Professor Yoon in prospect, “it will bring about technological innovation in display industry as it can fundamentally resolve the issue of shattering mobile phone displays, reduce the weight and thickness of large-area televisions, and apply Roll to Roll process in display manufacture.”
Supported by the Ministry of Knowledge Economy for five years, the technology has applied for 3 patents and is in discussion for technology transfer with related business.
Figure 1. The according (left) and discording (right) refractive indices of glass-fiber fabric and polyimide film. The characters on the left are sharp and clear, but the characters on the right appear foggy.
Figure 2. Picture of the developed glass-fiber fabric
2013.06.09 View 9412 -
6th TEDxKAIST Held on May 11, 2013
The sixth TEDxKAIST (https://www.facebook.com/TEDxKAIST?fref=ts) took place on May 11, 2013. The event was held under the theme, “Choice between Birth and Death,” and the slogan, “B-C-D,” which was inspired from Jean Paul Satre’s quote, “Life is a choice between birth and death.”
The following speakers gave talks on the choices they have made and the impacts on their lives: Sonya S. Kwak, Professor of the Industrial Design Department at Ehwa Women’s University; Meoung-Seok Oh, a college student majoring in dental technology and business at Korea University; SooA Yeo, CEO of “Chalk,” a social venture company that offers talent donations; and Jeong-Won Lee, a senior researcher at Medical Imaging Laboratory, Electronics and Telecommunications Research Institute (ETRI).
According to the speakers, every day we make decisions, and these decisions affect not only our own lives, but also our society as a whole. Speakers and participants explored the underlying relations between the choices being made and the outcome resulted therefrom. Attendees also shared their experiences and ideas that helped them to make the right decision and stressed the importance of choices we make in our lives.
TEDxKAIST is an event operating under the official license of TED to hold TEDx programs based on TED’s slogan “Ideas Worth Spreading.” Since the first event took place under the theme “Science for Happiness, Happiness for Science” on September 2010, TEDxKAIST has brought together over 300 participants through five successful events.
2013.05.31 View 8160 -
Complex responsible for protein breakdown in cells identified using Bio TEM
Professor Ho-Min Kim
- High resolution 3D structure analysis success using Bio Transmission Electron Microscopy (TEM), a giant step towards new anticancer treatment development
- Published in Nature on May 5th
Using TEM to observe protein molecules and analysing its high resolution 3D structure is now possible. KAIST Biomedical Science and Engineering Department’s Professor Ho-Min Kim has identified the high resolution structure of proteasome complexes, which is responsible for protein breakdown in cells, using Bio TEM.
This research has been published on the world"s most prestigious journal, Nature, online on May 5th. Our body controls many cellular processes through production and degradation of proteins to maintain homeostasis. A proteasome complex acts as a garbage disposal system and degrades cellular proteins when needed for regulation, which is one of the central roles of the body.
However, a mutation in proteasome complex leads to diseases such as cancer, degenerative brain diseases, and autoimmune diseases.
Currently, the anticancer drug Velcade is used to decrease proteasome function to treat Multiple Myeloma, a form of blood cancer. Research concerning proteasome complexes for more effective anticancer drugs and treatments with fewer side effects has been taking place for more than 20 years. There have been many difficulties in understanding proteasome function through 3D structure analysis since a proteasome complex, consisting of around 30 different proteins, has a great size and complexity.
The research team used Bio TEM instead of conventionally used protein crystallography technique. The protein sample was inserted into Bio TEM, hundreds of photographs were taken from various angles, and then a high–performance computer was used to analyse its structure. Bio TEM requires a smaller sample and can analyse the complexes of great size of proteins.
Professor Ho-Min Kim said, “Identifying proteasome complex assembly process and 3D structure will increase our understanding of cellular protein degradation process and hence assist in new drug development using this knowledge.” He added, “High resolution protein structure analysis using Bio TEM, used for the first time in Korea, will enable us to observe structure analysis of large protein complexes that were difficult to approach using protein crystallography.” Professor Kim continued, “If protein crystallography technology and Bio TEM could be used together to complement one another, it would bring a great synergetic effect to protein complex 3D structure analysis research in the future.”
Professor Ho-Min Kim has conducted this research since his post-doctorate at the University of California, San Francisco, under the advice of Professor Yifan Cheng; in co-operation with Harvard University and Colorado University.
Figure 1: A picture taken by Bio TEM of open state protein sample (proteasome complex)
Figure 2: Bio TEM image analysis showing protein 3D structure
2013.05.25 View 11244 -
Popular Science May 2013: Online Electric Vehicle (OLEV) Introduced as Part of Smart Roads
Popular Science (PopSci), a famous American monthly magazine publishing popular science articles for general readers on science and technology subjects, introduced KAIST’s Online Electric Vehicle (OLEV) in its latest issue of May 2013. For the article, please see the attachment.
2013.04.25 View 7838