• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2133-2135
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• 1998

Many semiconductive switches are operated in series for high voltage operation. The same number of gate drivers are needed to control all the switches, hence, the drivers cause high cost and system complexity. In this study, a simple and low cost gate driver for high voltage thyristor-diode switches is investigated. This gate driver can operate several high voltage thyristor-diode switches at the same time.

• Proceedings of The KACE
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• 2018.01a
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• pp.137-140
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• 2018

대한민국의 대표적인 구기 종목 중 하나인 농구는 입문 시 기본 동작에 적응하고 기본 규칙을 이해하기 위해 많은 시간이 소비된다. 또한 기존 농구 학습 분야에서 평가 수행 시 평가 대상자의 실력을 정량적으로 도출하는 것이 힘들어 중 고등학교 체육교과의 수행평가에서 객관적인 평가가 이루어지기 힘들었다. 본 연구에서는 이러한 농구 학습의 한계점을 해결하기 위하여 3축 자이로 센서와 스위치가 적용된 웨어러블 시스템을 기반으로 농구 학습을 도와주는 동작인식 기법을 제안한다. 그리고 실험을 통하여 제안하는 동작인식 기법의 성능을 검증하였으며, 생활체육 활성화를 통한 국민 건강증진과 객관적인 수행평가 실현에 기여할 것으로 기대된다.

• Proceedings of The KACE
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• 2018.01a
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• pp.133-136
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• 2018

최근 하드웨어의 컴퓨팅 능력이 좋아짐에 따라 기계학습 분야가 주목받고 있다. 이에 따라 많은 양의 데이터를 처리하기 수월해졌으며 수많은 데이터들을 기계학습 알고리즘을 통해 학습시키기 간편해졌다. 이러한 발전으로 기계학습이 적용되는 분야 또한 넓어져 교육 분야에도 활발히 적용되고 있다. 본 논문은 SVM(Support Vector Machine)을 사용하여 교실 내 좌석과 시간에 따른 졸음을 예측하는 기법을 제안한다. 제안하는 기법을 통해 교사들은 학생들의 졸음을 사전에 방지 하여 수업 진행에 큰 도움을 줄 것으로 기대된다.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1296-1299
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• 2000

A single stage AC/DC converter based on a full bridge topology suitable for high frequency soft switching converter applications is proposed. The proposed converter has high power factor, zero voltage switching, low noise and high efficiency. A pulse width modulation control is employed to reduce the switching and rectification losses respectively. This proposal converter has simple structure and low cost, The modelling and detailed analysis are performed to derive the design equations, a prototype converter has been designed and experimented. The new converter is attractive for high-voltage, high-power applications where IGBT's are predominantly used as the power switches. The principle of operation, features, and design are verified on a 1.5kW, 30kHz, IGBT based experimental circuit.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.340-342
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• 2015

스마트폰에 장착된 센서들을 사용하면 다양한 물리량을 측정할 수 있다. 본 논문에서는 스마트폰을 사용하여 물체의 높이를 추정하는 기법을 제시한다. 제안 기법은 물체를 여러 위치에서 관측하여 그 높이를 추정하는 것이다. 각각의 관측점에서는 스마트폰의 위치센서와 방향센서를 사용하여 관측점의 위치와 관측 방향을 측정한다. 이러한 관측값을 기반으로 각 관측점에서 물체로 향하는 3차원 시선백터를 도출하고 그것들 간의 최근점점을 계산하여 물체의 높이를 추정한다. 제안 기법을 모바일앱으로 구현하고 건축물 높이를 측정하는 실험을 통해 성능을 시험하였다.

• Journal of Engineering Education Research
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• v.13 no.5
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• pp.15-19
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• 2010

Upon request from the Tokushima Prefectural Senior High School of Science and Technology, two faculty staff members and eight students of The University of Tokushima visited the high school and set up a chemistry laboratory class for 59 students. Since the participating senior high school students were freshmen, four simple, safe and visual experiments were selected: 1) Water purification, 2) Surface modification, 3) Briggs-Rauscher reaction, and 4) Polymer synthesis and characterization. All experiments received a favorable reception as a follow-up questionnaire verified. Since the high school students enjoyed the experiments it is hoped that the results will strengthen the students' interest in chemistry. It was good opportunity for the observers; they recognized the difficulty of teaching students.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.87-90
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• 1989

The force acting on high Tc superconductors at 77K is measured and analyzed numerically. Both values are compared, and the difference between them is discussed. The forces, acting on a superconducting disk (thickness:1[mm], diameter:12[mm]) in an axially-symmetric magnetic field produced by a solenoid or a permanent magnet ring, are measured at 77K. The disk is an YBCO high Tc superconductor. The discrete surface current method(DSCM) is formalized for an axially-symmetric magnetic field. The forces of the superconducting disk in the magnetic field are analyzed using the DSCM, assuming that the disk is a perfect diamagnetic body. When the bottom side of the disk is separated 8[mm] from the top side of the solenoid, and the magnetic field applied on the center of the bottom side of the disk is 96[G], the measured value and the calculated value of the force are 96 and 496[mgf], respectively. The difference between them is caused by a non-perfect diamagnetism of the high Tc superconductor at 77K. It is proposed that a real force acting on high Tc superconductors at 77K can be estimated on the basis of a measured magnetic susceptibility of the high Tc superconductor at 77K and a calculated force of a perfect diamagnetic body.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2152-2154
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• 2009

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.5
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• pp.481-487
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• 2005

Proposed induction-heated system is innovative system which applied special high-frequency power circuit technique for thermal converse technique and IH(Induction-Heating) magnetic induction heating generated from induction-heated metallic package that is for distillation unit. In this occurs not burning, so that the working environment can be improved. This electromagnetic induction heating technique is used high frequency inverter, By using high frequency inverter high frequency alternative current in the range of [kHz] can be made with conventional alternative current. In this contribution IGBT module is used for high frequency inverter. This paper proposes new fluid heating method. Which is operated as follows. Working coil, which is wrapped outside of pipeline, makes the eddy current. Inside of heating vessel in isolated pipeline the specially designed stainless metallic package is inserted, which can be heated by eddy current losses. And then In this paper are discussed action analysis and characteristics analysis of 5[kW] class full-bridge resonant inverter system and resonant metallic package. In addition, by using this system, how high-efficiency heater is developed and application of system are also discussed.

• Journal of Korea Foundry Society
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• v.40 no.4
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• pp.118-127
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• 2020

Microstructural evolution during a heat treatment and high-temperature tensile properties have been investigated in conventionally cast CM247LC. In as-cast specimens, MC carbides with high amounts of Ta, Ti, Hf, and W were found to exist in the interdendritic regions, and γ' was observed in the form of cubes and octocubes prior to decomposition into cubes. In the heat-treated condition, some portion of eutectic γ-γ' remained, and uniform cubic γ' was observed in both interdendritic regions and dendrite core. Three types of carbides with different stoichiometries and compositions were found at the grain boundaries. MC carbides with high Hf contents were observed in the vicinity of eutectic γ-γ'. The highest tensile strength value was found at 750℃, whereas the greatest ductility appeared at 649℃. The effect of the temperature on the tensile properties was closely related to the dislocation structure. With increase in the test temperature, the density of dislocations inside γ' decreased, whereas that in the γ matrix increased. Stacking faults generated in γ' at 750℃ had a strengthening effect, whereas thermally activated dislocation motion at a high temperature was considered to have the opposite effect.