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Daejeon, South Korea

KAIST is a public research university located in Daedeok Innopolis, Daejeon, South Korea. KAIST was established by the Korean government with the help of American policymakers in 1971 as the nation's first research oriented science and engineering institution. KAIST has approximately 10,200 full-time students and 1,140 faculty researchers and had a total budget of US$765 million in 2013, of which US$459 million was from research contracts. From 1980 to 2008, the institute was known as the Korea Advanced Institute of Science and Technology. In 2008, the name was shortened to KAIST.KAIST ranked 60th globally and 12th in Asia in the QS World University Rankings , making it the second in the country, while it came second in the independent regional QS Asian University Rankings , considered as the best Korean institution. Moreover, it was placed 16th in Materials Science and 24th in Engineering and Technology by QS of the same year.Times Higher Education ranked KAIST the third best university under the age of 50 years in the world in its 2014 league table. In 2007 KAIST adopted dual degree programs with leading world universities to offer its students diverse educational opportunities and strengthen academic exchanges; since then with Carnegie Mellon University, the Georgia Institute of Technology, Technische Universität Berlin, and the Technische Universität München. Wikipedia.

Chung I.,Northwestern University | Chung I.,KAIST | Kanatzidis M.G.,Northwestern University
Chemistry of Materials | Year: 2014

Materials chemistry and the pursuit of new compounds through exploratory synthesis are having a strong impact in many technological fields. The field of nonlinear optics is directly impacted by the availability of enabling materials with high performance. Nonlinear optical (NLO) phenomena such as second harmonic and difference frequency generation (SHG and DFG, respectively) are effective at producing a coherent laser beam in difficult to reach frequency regions of the electromagnetic spectrum. Such regions include the infrared (IR), far-infrared, and terahertz frequencies. High performance NLO crystals are critical for applications utilizing these coherent light sources, and new materials are continuously sought for better conversion efficiency and performance. The class of metal chalcogenides is the most promising source of potential NLO materials with desirable properties particularly in the IR region where most classes of materials face various fundamental challenges. We review the recent developments in the discovery of several new high-performing chalcogenide NLO materials for the IR region of the spectrum. Among these, KPSe6, NaAsSe2, and Na2Ge2Se 5 have been shown to exhibit some of the highest SHG coefficients (χ(2)) reported, namely, 150, 325, and 290 pm/V, respectively. We focus on their structural characteristics, optical transparency, and nonlinear optical properties. We also discuss a new concept to prepare strong NLO bulk glasses, fibers, and thin films without poling, which would be a promising solution to a main challenge in NLO applications. The impact of cutting-edge theoretical calculations in helping to move this field of materials science and chemistry forward is highlighted. © 2013 American Chemical Society. Source

Kim K.I.,Max Planck Institute For Biologische Kybernetik | Kwon Y.,KAIST
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2010

This paper proposes a framework for single-image super-resolution. The underlying idea is to learn a map from input low-resolution images to target high-resolution images based on example pairs of input and output images. Kernel ridge regression (KRR) is adopted for this purpose. To reduce the time complexity of training and testing for KRR, a sparse solution is found by combining the ideas of kernel matching pursuit and gradient descent. As a regularized solution, KRR leads to a better generalization than simply storing the examples as has been done in existing example-based algorithms and results in much less noisy images. However, this may introduce blurring and ringing artifacts around major edges as sharp changes are penalized severely. A prior model of a generic image class which takes into account the discontinuity property of images is adopted to resolve this problem. Comparison with existing algorithms shows the effectiveness of the proposed method. © 2010 IEEE. Source

Spin–orbit torques arising from the spin–orbit coupling of non-magnetic heavy metals allow electrical switching of perpendicular magnetization. However, the switching is not purely electrical in laterally homogeneous structures. An extra in-plane magnetic field is indeed required to achieve deterministic switching, and this is detrimental for device applications. On the other hand, if antiferromagnets can generate spin–orbit torques, they may enable all-electrical deterministic switching because the desired magnetic field may be replaced by their exchange bias. Here we report sizeable spin–orbit torques in IrMn/CoFeB/MgO structures. The antiferromagnetic IrMn layer also supplies an in-plane exchange bias field, which enables all-electrical deterministic switching of perpendicular magnetization without any assistance from an external magnetic field. Together with sizeable spin–orbit torques, these features make antiferromagnets a promising candidate for future spintronic devices. We also show that the signs of the spin–orbit torques in various IrMn-based structures cannot be explained by existing theories and thus significant theoretical progress is required. © 2016 Nature Publishing Group Source

IEEE Transactions on Power Electronics | Year: 2011

A general phasor transformation theory for analyzing all linear ac converters such as inverters, rectifiers, cycloconverters, and resonant converters is suggested by unifying the circuit D-Q transformation for polyphase ac converters and the phasor transformation for single-phase ac converters. The system order of polyphase ac converters is degenerated to that of single-phase converters, and the switches in all ac converters, regardless of the numbers of switches and poles, are replaced with an equivalent transformer with a complex turn-ratio. The analysis of ac converters is drastically simplified by the proposed circuit-oriented approach. © 2011 IEEE. Source

Kim H.Y.,University of Texas at Austin | Lee H.M.,KAIST | Henkelman G.,University of Texas at Austin
Journal of the American Chemical Society | Year: 2012

Density functional theory was used to study the CO oxidation catalytic activity of CeO 2-supported Au nanoparticles (NPs). Experimental observations on CeO 2 show that the surface of CeO 2 is enriched with oxygen vacancies. We compare CO oxidation by a Au 13 NP supported on stoichiometric CeO 2 (Au 13@CeO 2-STO) and partially reduced CeO 2 with three vacancies (Au 13@CeO 2-3VAC). The structure of the Au 13 NP was chosen to minimize structural rearrangement during CO oxidation. We suggest three CO oxidation mechanisms by Au 13@CeO 2: CO oxidation by coadsorbed O 2, CO oxidation by a lattice oxygen in CeO 2, and CO oxidation by O 2 bound to a Au-Ce 3+ anchoring site. Oxygen vacancies are shown to open a new CO oxidation pathway by O 2 bound to a Au-Ce 3+ anchoring site. Our results provide a design strategy for CO oxidation on supported Au catalysts. We suggest lowering the vacancy formation energy of the supporting oxide, and using an easily reducible oxide to increase the concentration of reduced metal ions, which act as anchoring sites for O 2 molecules. © 2011 American Chemical Society. Source

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