• Bulletin of the Korean Chemical Society
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• 제16권10호
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• pp.929-933
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• 1995

The electronic band structure and electrical properties of KMo4O6 containing chains of condensed molybdenum octahedra are analyzed by means of the extended Hu&ckel tight-binding method. KMo4O6 has partially filled bands of 1D as well as 3D character. They also exhibit the anisotropic band dispersions with bandwidths much larger along the c* axis than along the directions perpendicular to it. Thus, conduction electrons are essentially delocalized along the c* direction (i.e., the chain of condensed molybdenum octahedra) in the solid. The 1D band of two partially filled d-block bands leads to Fermi surface nesting with the wave vector q=0.3c*. The CDW instability due to this nesting is expected to cause the phase transition associated with the resistivity anomaly at low temperature. The characteristics of metallic behavior in the crystallographic ab plane are explained on the basis of the unnested 2D Fermi surfaces.

• 대한인간공학회지
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• 제15권2호
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• pp.139-147
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• 1996

It is known fact that the CTS patients have lower pinch strength than the normal people. And we can assume that the sensory nerve action potential(SNAP) and the nerve conduction velocity(NCV) of the CTS group are lower or slower than the normal subjects. This paper analysed the grip strength and performed EMG experiment for the group Norm, G1 and G2. The results are as follows: 1) CTS patients have lower pinch strength than normal people. 2) There was no significant difference on SNAP between the CTS group and the normal group. 3) There was significant difference on NCV among Norm, G1, and G2 group. Especially, significant level was higher in the evening after the continuous use of wrist.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1168-1170
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• 1995

The purpose of this thesis is to fabricate the hexamethyldisiloxane thin film by plasma polymerization method, and to investigate the electric conduction characteristics of plasma polymerized thin film. Current density was measured in being changed annealing temperature(room temperature${\sim}125[^{\circ}C]$) and electric field intensity($10^5{\sim}1.2{\times}10^6$[V/cm]). The current density of thin films fabricated at discharge power of $30{\sim}90$[W] showed $1.3{\times}10^{-11}{\sim}3.1{\times}10^{-12}[A/cm^2]$ after 10 minutes of permission of electric field. The current density increased gradually with increasing of annealing temperature and electric field intensity. The electric conduction type of thin films fabricated in discharge power of 90[W] agreed with Schottky type.

• 한국세라믹학회지
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• 제41권8호
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• pp.623-627
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• 2004

Ba가 첨가된 LaBaGa $O_4$ 층상 perovskite의 생성상과 전도거동에 대해 고찰하였다. LaBaGa $O_4$의 La-site에 20at% 이하의 $Ba^{2＋}$ 이온을 첨가한 조성은 $K_2$Ni $F_4$구조 사방정 단일상을 형성하였다. 건조분위기에서 L $a_{0.8}$B $a_{1.2}$G $a_{3.9}$는 높은 산소분압영역에서 산소이온전도와 hole(p-type)전도의 혼합전도를 나타내었다. 수증기분위기에서는 수증기가 산소빈자리로 유입되어 proton전도가 발생되었으며, 온도가 낮아질수록 총전도에 대한 proton 전도도의 기여가 증가하여 35$0^{\circ}C$ 이하의 온도에서는 proton 전도가 지배적인 전도를 나타내었다. Proton 전도에 대한 활성화 에너지는 0.72 eV였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.546-548
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• 2005

This paper proposes a unity power factor ZVT PWM single-phase rectifier. The ZVT soft switching are achieved by using a simple ZVT circuit, and the reduced conduction losses are achieved by employing a single-stage converter, instead of a typical double-stage converter composed of front end diode rectifier and cascaded boost rectifier. Furthermore, thanks to good features such as simple PWM control at constant frequency, low switch stress and low VAR rating of commutation circuits, it is suitable for high power applications. The principle of operation is explained in detail, and simulation results of the new converter are also included.

• 한국전산유체공학회지
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• 제16권3호
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• pp.47-51
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• 2011

Dark Mura phenomena which can happen at the region with high temperature gradient in a Notebook LCD Monitor using LED light source has numerically been studied. The calculation was conducted under the nearly realistic conditions by considering the anisotropic thermal properties of materials and the real dimensions of each component. The two performance indices of LED monitor, i.e., the maximum temperature and the spacial gradient of temperature were examined for the various shapes, lengths and thickness of heat sink plate. Calculated results give more reasonable temperature distribution comparing with experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.321-324
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• 1995

Switched reluctance motors and drives are increasingly used in high speed applications due to their robust mechanical structures, low inertia, and reduction in the rotor losses. The turn-on angle has to be advanced as the motor speed increases, but it may cause the starting problem in some rotor positions. In this paper, the characteristics of the maximum speed and input voltage with the advance angle at high speeds is investigated. To overcome the starting problem and reduce the torque ripple, conduction overlapping is added in adjacent phases. The effectiveness of conduction overlapping is verified through the simulation and experiments.

• 전력전자학회논문지
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• 제22권4호
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• pp.312-323
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• 2017

This paper introduces the bidirectional dc-dc converter design case study, which employs silicon-carbide (SiC) MOSFETs for battery energy storage system (BESS). This converter topology is selected as bidirectional synchronous buck converter, which is composed of a half bridge converter, an inductor, and a capacitor, where the converter has less conduction loss than that of a unidirectional buck and boost converter, and to improve the converter efficiency, both the power stage design and power conversion architecture are described in detail. The conduction and switching losses are compared among three different SiC devices in this paper. In addition, the thermal analysis using Maxwell software of each switching device supports the loss analyses, in which both the 2 kW prototype analyses and experimental results show very good agreement.

• E2M - 전기 전자와 첨단 소재
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• 제9권7호
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• pp.708-718
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• 1996

The microstructure and electrical properties of the nonlinear ZnO varistor with A1$_{2}$ $O_{3}$ additions is investigated. The variation of nonlinear behavior with A1$_{2}$ $O_{3}$ additions is indicated from J-E and C-V measurement to be a result of the change of the interface defects density $N_{t}$ at the grain boundaries and the donor concentration $N_{d}$ in the ZnO grains. The optimum composition which has the nonlinear coefficients of -57 was observed in the sample with 0.005wt% A1$_{2}$ $O_{3}$ additions. The conduction mechanism at the pre-breakdown region is consistent with a Schottky thermal emission process obeying a relation given by $J^{\var}$exp[-(.psi.-.betha. $E^{1}$2/)kT] and the conduction process at the breakdown region follows a Fowler-Nordheim tunneling mechanism of the form $J^{\var}$exp(-.gamma./E).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.957-958
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• 2007

The conduction-cooled HTS SMES magnet is operated in cryogenic temperature. The insulation design at cryogenic temperature is an important element that should be established to accomplish miniaturization that is a big advantage of HTS SMES. However, the behaviors of insulators for cryogenic conditions in air or vacuum are virtually unknown. Therefore, we need active research and development of insulation concerning application of the conduction-cooled HTS SMES. Specially, this paper was studied about high vacuum and cryogenic temperature breakdown and flashover discharge characteristics between cryocooler and magnet-coil. The breakdown and surface flashover discharge characteristics were experimented at cryogenic temperature and vacuum. Also, we were experimented about mechanical properties of 4-point bending test. From the results, we confirmed that about research between cryocooler and magnet-coil established basic data in the insulation design.