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Photonic crystals allow the fabrication of miniaturized spectrometers By Courtesy of Nanowerk Photonic crystals allow the fabrication of miniaturized spectrometers (Nanowerk Spotlight) Spectrometers are used in materials analysis by measuring the absorption of light by a surface or chemical substance. These instruments measure properties of light over a specific portion of the electromagnetic spectrum. In conventional spectrometers, a diffraction grating splits the light source into several beams with different propagation directions according to the wavelength of the light. Thus, to achieve sufficient spatial separation for intensity measurements at a small slit, a long light path – i.e., a large instrument – is required. However, for lab-on-a-chip or microTAS (total analysis system) applications, the spectrometer must be integrated into a sub-centimeter scale device to produce a stand-alone platform. To achieve this, researchers at the Korea Advanced Institute of Science and Technology (KAIST) propose a new paradigm in which the spectrometer is based on an array of photonic crystals with different bandgaps. "Because photonic crystals refelct light of different wavelengths selectively depending on their bandgaps, we can generate reflected light spanning the entire wavelength range for analysis at different spatial positions using patterned photonic crystals," Seung-Man Yang, Director of the National Creative Research Initiative Center for Intergrated Optofluidic Systems and Professor of the Department of Chemical & Biomolecular Engineering at KAIST, tells Nanowerk. "Therefore, when the light source impinges on the patterned photonic crytals, we can construct the spectrum using the reflection intensity profile from the constituent photonic crystals." Photonic crystals – also known as photonic band gap material – are similar to semiconductors, only that the electrons are replaced by photons (i.e. light). By creating periodic structures out of materials with contrast in their dielectric constants, it becomes possible to guide the flow of light through the photonic crystals in a way similar to how electrons are directed through doped regions of semiconductors. The photonic band gap (that forbids propagation of a certain frequency range of light) gives rise to distinct optical phenomena and enables one to control light with amazing facility and produce effects that are impossible with conventional optics. To demonstrate this new concept based on patterned photonic crystals, Yang and his group used non-close-packed colloidal crystals of silica particles dispersed in photocurable resin. Due to the repulsive interparticle potential, monodisperse silica particles spontaneously crystallize into non-close-packed face-centered cubic (fcc) structures at volume fractions above 0.1. Therefore, the particle volume fraction determines both the lattice constant and the bandgap position. a) Optical image of an ETPTA film containing porous photonic crystal stripe patterns with 20 different bandgaps. b) Reflectance spectra from the 20 strips. c) Optical microscope image of the middle region with the parallel stripe pattern (denoted as white-dotted box in a). d) Cross-sectional SEM images of first, sixth, eleventh and seventeenth strips. The scale bars in a, c and d are 1 cm, 2mm and 2 µm, respectively. (reprinted with permission from Wiley-VCH Verlag) Reporting their findings in a recent issue of Advanced Materials ("Integration of Colloidal Photonic Crystals toward Miniaturized Spectrometers"), the KAIST team has demonstrated the integration of colloidal photonic crystals with 20 different bandgaps into freestanding films (prepared by soft lithography), and their application as a spectrometer. Yang explains that the team was able to precisely control the photonic bandgap by varying the particle size and volume fration. "The prepared colloidal composite structures showed high physical rigidity and chemical resistivity" he says. "The composite structure is suitable for spectroscopic use due to the small full widths at half maximum (FWHMs) of the reflectance spectra, which mean that there is little overlap of the reflectance spectra of neighboring photonic crystal strips." "On the other hand" says Yang, "porous photonic crystals showed large FWHMs and high reflectivities, which should prove useful in many practical photonic applications that require high optical performance and physical rigidity as well as simple and inexpensive preparation." In addition to fabricating miniaturized spectrometers, which can for instance be integrated into small lab-on-a-chip devices, these integrated photonic crystals can be potentially used for tunable band reflection mirrors, optical switches, and tunable lasing cavities. Moreover, patterned photonic crystals with RGB colors are well-suited for use in reflection-mode microdisplay devices. Yang points out that, although the spectrometric resolution can be reduced by employing the smaller bandgap interval and photonic bandwidth, there is a limitation. "Now, we are studying photonic crystals with continuous modulation of bandgap position. We expect that the photonic crystals can reduce the resolution to 0.01 nm." By Michael Berger. Copyright 2010 Nanowerk
2010.03.17 View 13098
Indoor Localization System for Mobile Devices Developed by KAIST Research Team The technology will be available to smart phone users around the world through Goole Apps Store. The wireless fidelity (WiFi)-based indoor localization can be installed on smart phones for commercialization, a technology developed by a research team at KAIST. The KAIST research team, led by Professor Dong-Soo Han, Department of Computer Science and Engineering, explained that the technology offers smart phone users, e.g., Google’s Android phone and Apple’ iPhone, a unique way to recognize their location through WiFi Open Radio Map. WiFi Open Radio Map is built with WiFi Location Fingerprint that contains wireless local area network (LAN)’s signal strength and wireless access points (AP) number, and with location information. Through using the Map, WiFi-based indoor localization recognizes the location of smart phones and sends the location information to the phones. Since the technology uses WiFi signal information only to recognize the whereabouts of phones, it can be widely used in the future, without installing extra machines and equipment for detection, for a complicated, large indoor environment, where the Global Positioning System (GPS) is not available. Currently, Professor Han has established WiFi Open Radio Map inside and outside of a few buildings at KAIST and developed several location based application services to perform a beta testing. He plans to open and distribute the technology to smart phone users through Google and Apple Apps Store in early 2010. Collaborations with major smart phone makers such as SK Telecom, Korea Telecom, and Samsung as well as outdoor/indoor localization manufactures and suppliers will also be sought, according to Professor Han. Professor Han is invited to an international conference, Eighth Annual IEEE International Conference on Pervasive Computing and Communications, slated for early April 2010, in recognition of his work. At the conference, he will give a presentation on WiFi based indoor localization technology and conduct its demo version.
2010.02.10 View 10985
Prof. Choi Unveils Method to Improve Emission Efficiency of OLED A KAIST research team led by Prof. Kyung-Cheol Choi of the School of Electrical Engineering & Computer Science discovered the surface plasmon-enhanced spontaneous emission based on an organic light-emitting device (OLED), a finding expected to improve OLED"s emission efficiency, KAIST authorities said on Thursday (July 9). For surface plasmon localization, silver nanoparticles were thermally deposited in a high vacuum on cathode. Since plasmons provide a strong oscillator decay channel, time-resolved photoluninescene (PL) results displayed a 1.75-fold increased emission rate, and continuous wave PL results showed a twofold enhanced intensity. "The method using surface plasmon represents a new technology to enhance the emission efficiency of OLED. It is expected to greatly contribute to the development of new technologies in OLED and flexible display, as well as securing original technology," Prof. Choi said. The finding was published in the April issue of Applied Physics Letters and the June 25 issue of Optics Express. It will be also featured as the research highlight of the August issue of Nature Photonics and Virtual Journal of Ultrafast Science.
2009.07.09 View 19146
KAIST Research Team Discovers Process for Rapid Growth of N-Doped CNT Arrays A team of scientists led by Profs. Sang-Ouk Kim, Won-Jong Lee and Duck-Hyun Lee of the Department of Materials Science and Engineering has found a straightforward process for rapid growth of wall-number selected, nitrogen-doped carbon nanotube (CNT) arrays, university officials said on Monday (March 16). KAIST researchers prepared highly uniform nanopatterned iron catalyst arrays by tilted deposition through block copolymer nanotemplates. This remarkably fast growth of highly uniform N-doped CNTs, whose material properties and chemical functionalizability are reinforced by N-doping, offers a new area of a large-scale nanofabrication, potentially useful for diverse nano-devices. Carbon nanotubes (CNTs) are of broad technical interest in electronics, photonics, energy devices, and other applications. However, establishing a straightforward process for mass production of uniform CNTs with desired structure and properties has been a long-standing challenge. In particular, it was strongly desired to precisely control the numbers of walls and diameter of CNTs, which are decisive parameters for the physical properties of CNTs. In this respect, the preparation of monodisperse catalyst array having a narrow size distribution is generally considered an effective pathway to produce well-defined CNTs, since the number of walls and diameter of the produced CNTs are closely related to the catalyst size. The finding was featured in the March 13 edition of Nano Letters, a leading journal in the nano technology field.
2009.03.20 View 13174
Research University Presidents Discuss Global Network to Increase Cooperation Presidents and leaders of research universities participating in the 2008 International Presidential Forum on Global Research Universities (IPFGRU) held at the Westin Chosun Hotel in Seoul, Korea on Sept. 8, 2008 exchanged views and ideas on how to build and effectively utilize a global research network in order to increase cooperation and exchanges among institutions of science and technology across the world. The participants agreed on the need to promote the sharing of expertise and facilities, conduct joint researches and positively implement dual degree, roaming professorship and other programs that help institutions in societies at different stages of scientific and technological development maximize the fruits of their research activities. As a major goal, the participants agreed to create alliances for research and education that can become a new paradigm for global cooperation, with the outcome of discussions at the 2008 IPFGRU providing the guidelines for future endeavors in this direction. Through the day-long symposium, participants reached general agreements on the following points: --The concept of sharing faculty or roaming professorship should be actively promoted in order to accelerate global dissemination of academic expertise with the institutions and state authorities concerned easing existing restrictions to such arrangements and ensuring maximum academic freedom of professors involved. --Dual degree programs especially those involving institutions of different countries need to be further encouraged in view of their benefits of resources sharing, expansion of knowledge and cultural exchanges and that educational authorities should try to remove various forms of limitations. --As competitions over university ranking would grow intensive as institutions seek to attract better students and more donations, there is need to institutionalize a fairer, globally recognized national, regional and international assessment systems. --In view of rapid expansion of interdisciplinary researches which calls for the sharing of facilities and expertise among different institutions, it is necessary to establish national or regional hubs to make state-of-the-art facilities and equipment available for researchers and research programs experiencing limitations in financial and material resources. --National governments and political leaders should better recognize the importance of science and technology for societal and global prosperity and the science and technology community needs to make more communicative approaches to politicians so that greater trust may be built between them. --Arrangements to conduct joint research involving international industries, academia and government should be accelerated with a view to addressing the common problems facing the mankind in the 21st century, including energy, environment, water, food and sustainability. The United Nations and other international organizations need to provide stronger support for research universities’ efforts in this direction. --Research universities across the world should make concerted efforts to establish a global cooperative network that can facilitate the flow of information, resources and research personnel to realize universal advancement of science and technology and, ultimately, enhance the quality of human life. Keynote speakers and panelists and the subjects of their presentations were: Participants" List Topic Name of University Speaker Position 1. Roaming Professorships: To Whose Benefit? Illinois Institute of Technology John L. Anderson President Improving the Competitiveness of Global University Education National University of Sciences and Technology Muhammad Mushtaq Pro-Rector Improving the Competitiveness of Global University Education Tianjin University Fuling Yang Director of International Cooperation Office Sharing Differences in Culture and Environment for Sustainable Education for the Future Generation Kumamoto University Tatsuro Sakimoto President Sharing Differences in Culture and Environment for Sustainable Education for the Future Generation Odessa National I. I. Mechnikov University Sergiy Skorokhod Vice Rector for International Cooperation Promoting Science and Engineering Education among Secondary Students Czech Technical University of Prague Miroslav Vlcek Vice Rector Promoting Science and Engineering Education among Secondary Students South China University of Technology Xueqing Qiu Vice President Preserving and Utilizing Expert Knowledge for Better Education Eotvos Loran University Jösef Nemes-Nagy Vice Dean 2. Dual Degree Programs: Future Potential & Challenges University of Queensland Paul Greenfield President and Vice Chancellor Benefits of Dual Degree Program Institut National des Sciences Appliquées de Lyon Martin Raynaud Director, International Relations Benefits and Limitations of Dual Degree Program National Institute of Development Administration Pradit Wanarat Vice President for Academic Affairs The Role of Dual Degree Program Easing Brain Drain Nanyang Technological University Lam Khin Yong Associate Provost, Graduate Education & Special Projects International Dual Degree Programs and Strategies Georgia Institute of Technology Steven W. McLaughlin Vice Provost, International Initiatives Dual Degree Program and Global Learning Networks City University of Hong Kong Richard Yan-Ki Ho Special Advisor to the President Raising International IQs of Scientists and Engineers for Global Enterprise Technion, Israel Institute of Technology Moshe Shpitalni Dean, Graduate Studies Luncheon Speech “Beneficial Relationships between Academia and Companies” Medical Information Technology A. Neil Pappalardo Chairman and CEO 3. Sharing Facilities and Expertise KAIST Nam Pyo Suh President Promoting International Sharing of Research Facilities and Expertise to Strengthen Research Outcomes Griffith University Ian O"Connor President Economic Benefits of Sharing Research Facilities and Expertise POSTECH Sunggi Baik President Economic Benefits of Sharing Facilities and Expertise: National NanoFab Center National NanoFab Center Hee Chul Lee President Communicating Science and Technology to Political Leaders Office of the President of KOREA Chan Mo Park Special Advisor to the President for Science and Technology Filling the Gap of University Resources Bandung Institute of Technology Djoko Santoso Rector 4. An Approach to Joint Research Ventures with NASA NASA Yvonne Pendleton Deputy Associate Center Director Benefits of International Joint Venture Research Projects University of Adelaide Martyn J. Evans Director, Community Engagement Benefits of International Joint Projects Mahidol University Sansanee Chaiyaroj Vice President International Joint Research Projects University of Iowa P. Barry Butler Dean, College of Engineering Joint Research: University of Technology Malaysia’s Experience at National and International Level University Technology of Malaysia Tan Sri Mohd Ghazali Vice-Chancellor Sharing Intellectual Property Rights Paris Institute of Technology Cyrille van Effenterre President Global Economic and Social Contribution of International Joint Project Cooperation Kyushu University Wataru Koterayama Vice President 5. Globalization through Interfacing with Existing Networking Technical University of Denmark Lars Pallesen Rector Establishing Global Science and Technology Networking National Cheng Kung University Da Hsuan Feng Senior Executive Vice President Establishing Global Science and Technology Networking University of Technology of Troyes Christian Lerminiaux President The Role of Global Science and Technology Network for Higher Education in the 21st Century Iowa State University Tom I-P. Shih Department Chair Regionalized or Globalized Science and Technology Networking Babes-Bolyai University Calin Baciu Dean, Faculty of Environmental Sciences Globalized Science and Technology Networking Harbin Institute of Technology Shuguo Wang President Connecting Regional Science and Technology Networks for the Global Networking Ritsumeikan University Sadao Kawamura Special Aide to the Chancellor How Can a Publisher Strengthen the Global Network of Universities? Elsevier Youngsuk Chi Vice Chairman
2008.09.18 View 19827
New System to Generate Extreme-Ultraviolet Light Developed A KAIST research team led by Prof. Seung-Woo Kim of the Mechanical Engineering Department developed a new system for generating coherent extreme-ultraviolet (EUV) light, school authorities announced on June 5. The new system comes in a metallic nano-structure consisting of a two-dimensional array of gold "bow tie" elements on a sapphire plate. The new process was featured in the British journal Nature on June 5. The properties of coherent EUV light make it a prime candidate for exciting technological applications. But, at present, the equipment needed to generate the short-wavelength light is costly and bulky. The system developed by Prof. Kim"s research team is expected to reduce both cost and bulk. The new system uses the conventional principle of high-harmonic generation via the interaction of a femtosecond laser pulse with a gas, but adopts the novel concept of amplifying light by way of local plasmon field enhancement, according to the research team.
2008.06.10 View 12466
KAIST Students Wins Gold Prize at Technical Idea Contest KAIST Students Wins Gold Prize at Technical Idea Contest - Receive the gold prize at the 3rd High-Tech Daejeon Technical Idea Contest for Company Establishment- For the development of a new system to convert complex web page addresses to short and meaningful addresses Sang-Hoon Kim, Song-Hwa Chae and Dong-Hun Lee of Chemical and Biomolecular Engineering won the gold prize at the prospective company establishment part in the 3rd High-Tech Daejeon Technical Idea Contest for Company Establishment on May 21 for their valuable development of ‘Web Page Address Clipping System’. So far, simplified web page addresses include special characters, which make the addresses long and complex. That is, the current address simplification service combines meaningless random words and numerals to create addresses when web page addresses are entered. In this case, the addresses are not easy to share with others and reuse several times since they are difficult to memorize. However, the ‘Web Page Address Clipping System’ shortens meaningless long addresses. In addition, the improved address simplification service will provide user’s own addresses, and statistics and ranking to clipping addresses frequently used. Based on this technology, Kim and Chae are now preparing to open a company called ‘URLClip’ under the auspice of Professor Tae-Yong Yang and Researcher In-Soo Kim, KAIST Entrepreneurship Center. They are also expanding their service areas onto clipping library for individual users, host name services for enterprises, etc. and developing tool bar, RSS service (RSS is an acronym of RDF (or Rich) Site Summary. It refers to a service that automatically and easily provides frequently updated contents such as news and blogs to users), etc. to improve users’ conveniences. URLClip (http://www.urlclip.net) is a next generation portal site, which is expected to provide a variety of individualized services based on Web Page Address Clipping Service and to be used by many enterprises as well as individual users who wish to enhance their access to useful contents. “Chemical & Biomolecular Engineering Professor Sun-Won Park has offered lots of helps and supports, so I could decide to commercialize the developed technologies. The application of this technology to real life will allow further comfortable uses of internet to users,” Kim said. Narae Team received the best prize last April at the 2nd Pre-Star Venture Company-Opening Contest hosted by KAIST and Hanbat Univeristy, and the technology is pending a patent application. Inquiry:Sang-Hoon Kim, Dep. of Chemical and Biomolecular Engineering, H.P. 010-4754-9947Song-Hwa Chae, Dep. of Chemical and Biomolecular Engineering, H.P. 010-7223-9947Home page: http://www.urlclip.netEmail: urlclip@urlclip.net
2007.06.05 View 14716
Gold prize for Sungkoo Yeo and silver prize for Youngsik Kim at 'Samsung Electrics paper contest' Gold prize for Sungkoo Yeo and silver prize for Youngsik Kim at ‘Samsung Electrics paper contest’ Sungkoo Yeo, doctorate student at the division of Electrical Engineering, and Youngsik Kim, doctorate students at the division of Mechanical Engineering, won gold and silver prizes respectively at ‘the 2nd Inside edge paper contest’ organized by Samsung Electronics. Yeo, under the supervisory of Professor Youngse Kwon, won the glory of gold prize in recognition of his highly evaluated researches in the fields of silicon-based micro mold manufacturing technologies and fine shaping technologies revealed by his paper of ‘"Fabrication of Microlens array Using PDMS Replica Molding and Oxidized Porous Silicon Bulk Micromachining’. Kim, under the supervisory of Professor Seungwoo Kim, also won the silver prize for his research performances over the thickness pattern measuring technologies of transparent thin film coated on the pattern of an opaque metal in the field of optical technology unveiled by his paper of "Dispersive white-light interferometry for in-line inspection of thin-film layers on patterned structures". Inside Edge paper contest is an academic paper contest organized by Samsung Electronics to reveal the fresh ideas and potential technologies of the young talented.
2006.11.27 View 15281
Sungil Chung listed in Who's Who following last year Sungil Chung listed in Who’s Who following last year Sungil Chung, senior researcher of KAIST Satellite Technology Research Center (STRC), is listed in the international biographical dictionary Marquis Who"s Who’s Who’s Who in the America Edition 2007 following last year. He is also listed in the first edition of Who’s Who of Emerging Leaders. Ph.D. Chung majored in Electrohydrodynamics (EHD) at Texas A&M University and worked at NASA’s Goddard Space Flight Center for a research in the field of aerospace vehicle-related thermal control. He has worked at KAIST STRC as senior researcher from September this year. He has won an Innovation and Creativity Prize Paper Award from the U.S. Institute of Electrical and Electronics Engineers (IEEE) in 2004.
2006.11.16 View 15087

KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea T.042-350-2114 F.042-350-2210(2220)