• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.67-70
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• 1995

Amorpous As$\sub$10/Ge$\sub$15/Te$\sub$75/ device shows the memory switching characterisite under d.c. bias. In bulk material, a-As$\sub$10/Ge/sub15/Te$\sub$75/s switching voltage range is above 100 volts. Our purposes in this gaudy are decreasing a switching threshold voltage, finding the properties of d.c., a.c. conduction, and the characterisitics of switching threshold voltage fur a-As$\sub$10/Ge$\sub$15/Te$\sub$75/. As the results, the d.c.and a.c. conductivities increase with temperature. From the data of conductivity, various electrical and physical properties are obtained experimentally. The switching threshold voltages decrease with increasing annealing temperature and time, but increase with increasing film thickness and distance of electrode for d.c. bias.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.119-120
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• 2014

멀티레벨 인버터는 낮은 고조파 성분을 갖고, 제한된 정격 스위칭 소자로 대용량 전력변환이 요구되는 시스템에 매우 효율적이다. 수학적인 해석방법을 통해 전도손실, 스위칭 손실, 출력 전압 전류의 THD의 해석방법을 제시하고 시뮬레이션을 통해 멀티레벨 인버터의 특성을 비교 분석을 한다. 본 논문은 기존 제안된 멀티레벨 구조인 NPC(Neutral Point Clamped) 멀티레벨 인버터, Cascaded H-bridge 멀티레벨 인버터, Flying capacitor 멀티레벨인버터를 기반으로 25MW급 대용량 인버터의 손실 및 출력특성을 비교 분석하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.5
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• pp.455-462
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• 2003

Switching PFC converters are widely used not only to comply the power quality specification but also for maximum efficiency. However switching PFC converters generate serious electromagnetic interference(EMI). In this paper to solve this problem, we applied the APW(Anti-Phase Winding) and RPWM(Random PWM) technique to PFC boost converter and obtained good results. Simulation and experimental results show the improved harmonics and reduced EMI effect in air-conditioner system.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.189-190
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• 2014

본 논문에서는 높은 동작 주파수에서 컨버터를 구성하는 수동 소자들의 사이즈가 작아져, 전력밀도가 증가하는 장점을 이용하기 위하여 500 kHz에서 동작하는 LLC 공진형 컨버터를 제안하였다. 500 kHz에서 기존의 PWM컨버터는 스위칭 손실이 높아 효율이 떨어지고, Asymmetric Half Bridge 컨버터는 2차측 다이오드에 걸리는 전압이 비대칭이기 때문에 전도 손실을 줄이기가 어려우며 경부하 시 ZVS를 유지하기 어렵다. 이러한 문제점을 해결하기 위해 작은 순환 에너지와 작은 Turn off 스위칭 손실을 가지며 경부하 시에도 ZVS를 유지할 수 있는 LLC 공진형 컨버터를 설계 및 제작하고 500 kHz의 고주파에서 높은 전력밀도를 얻을 수 있음을 검증하였다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.28-30
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• 2020

본 논문에서는 위상천이 풀브릿지(PSFB) 컨버터에 적용할 수 있는 새로운 클램핑 회로를 제안한다. 제안하는 회로가 적용된 PSFB 컨버터는 정류기 다이오드의 전압 발진을 완전히 제거되면서도, 영전압 스위칭(ZVS)을 위한 전류를 보장하기 때문에 전도 손실과 스위칭 손실을 모두 개선하여 고효율을 달성할 수 있다. 뿐만 아니라, 출력 인덕터 부피와 듀티 손실 측면에서도 장점을 갖기 때문에 기존에 제안된 여러 클램핑 회로들에 비해서도 높은 효율과 높은 전력밀도를 갖는다. 제안된 회로의 타당성은 385V 입력, 270-420V 출력의 3.3kW 전기차 충전기 프로토타입으로 검증되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.1
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• pp.53-58
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• 2001

The main noise sources in SMPS are divided into three parts: the switching devices, the rectifiers in secondary part, the output transformer and choke coil. In this paper we performed the noise analysis with respect to bobbin type and winding method, and designed an optimized transformer focusing on the transformer. For the comparison. we measured four parameters for each cases, including EMI conducted emission noise. signal from the switching devices, output ripple/noise voltage and leakage current. As the result, the transformer using a vertically-typed bobbin and a parallel, sandwich winding method showed the best performance. We confirmed that the SMPS developed in this research is satisfied with the IEC 601-1 international standard for the medical instrumentation. by testing its electrical characteristics and safety.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.10-16
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• 2004

In this thesis, improved full wave mode ZVT(Zero-Voltage-Transition) PMW DC-DC Converters are presented to maximize the regeneration ratio of resonant energy by only putting an additional diode In series with the auxiliary switch. The operation of the auxiliary switch in a half wave mode makes it possible soft switching operation of all switches including the auxiliary switch whereas it is turned off with hard switching in conventional converter. The increase of the regeneration ratio to resonant energy results in low commutation losses and minimum voltage and current stresses. The operation principles of the improved ZVT PWM DC-DC Converters are theoretically analyzed using the boost converter topology as an example. Both theoretical analysis and experimental results verify the validity of the PWM boost converter topology with the improved full wave mode ZVT PWM converters.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.173-178
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• 2009

We have investigated the electrical properties of oxide metal thin film device. The device has been fabricated top-top electrode structure and its transport properties are measured in order to study the resistance change. Electrical properties with linear voltage sweep on a electrodes are used to show the variation of resistance of oxide metal thin film device. Fabricated oxide metal thin film device with MIM structure is changed from a low conductive Off-state to a high conductive On-state by the external linear voltage sweep. The $Si/SiO_2/MgO$ device is switched from a high resistance state to a low resistance state by forming. Consequently, we believe oxide metal is a promising material for a next-generation nonvolatile memory and other electrical applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.235-240
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• 2020

This study evaluated the improvements for circuits of a combat vehicle distribution box to reduce the noise generated in electromagnetic compatibility (EMC) testing. An analysis of the distribution boxes that failed the standard revealed the conducted noise generated from the converter and semiconductor switching elements on the circuit board. The distribution box transfers power from the generator and battery to the cooling system of a combat vehicle to keep turning the air conditioner on and off. Two methods were proposed to overcome this problem: a passive filter was added to the circuit board for the first method, and the converter and switching elements were replaced with the relays for the second method. Both methods were effective in reducing noise, but a greater improvement was obtained from the second method. The second method was applied to a combat vehicle system and was found to be suitable according to the EMC standards.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.2
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• pp.41-48
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• 1997

Nowadays, EMI emission characteristics, which causes harmful effect on power distribution system and other equipments, have been studied in field of Power electronics, vigoriously. So, in this paper, the conducted EMI emission is measured and compared for 3-phase diode rectifier and PWM converter according to switching frequency variation and current control method change using LISN(Line Impedance Stabilization Network) and spectrum analyzer.