• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.5-8
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• 2018

Recently, global warming and tropical nights have caused the use of electric fans to explode. Under these circumstances, running the fan for long periods of time is not only a risk of explosion due to overloading the power but also a small amount of electricity and environmental pollution. Therefore, the research was conducted to develop devices that automatically turn fans on and off according to room temperature, reducing the risk of explosion as well as saving energy. This study suggested that electric fans turn on and off automatically and display temperature in mobile applications. The ability to turn on and off allows the fan to turn on itself if the indoor temperature rises above a certain level. Conversely, if the indoor temperature drops below a certain level, the fan should be turned off. Second, the temperature display function checks indoor temperature through mobile applications. The automatic on/off capabilities proposed in this study could contribute to reducing the risk of explosion and saving energy. However, if the indoor temperature rises above a certain temperature even though there is no one inside, the fan can be turned on. The expectation from this study is that the ability of fans to operate and turn off at appropriate temperatures can reduce the risk of explosion, electrical charges, and environmental pollution.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.147-148
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• 2006

Sl-Thyristor는 기존의 Power semlconductor인 단일 IGBT,MOSFET과 비교하여 높은 정격 전압과 대전류의 소호가 가능하며 빠른 turn on swithcing time을 가지는 특성이 있다. 하지만 게이트 드라이버를 이용한 Sl-Thyristor의 turn on 구동시에는 전압구동의 특성과 turn 0ff시에는 전류 구동의 특성에 가까운 구동 특성이 요구되기 때문에 스위칭 요구 특성에 맞는 게이트 드라이버의 설계 및 제어가 쉽지 않다. 본 논문은 펄스 파워 어플리케이션으로 Sl-Thyristor(PT-201 5kV/100A)를 사용하여 pulsed power moduiator용 Sl-Thyristor의 게이트 드라이버의 요구인 빠른 turn on switching 특성과 turn off 시 Si-Thyristor 내의 전하를 빨리 제거하기 위한 조건을 제시하고 있다.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.395-400
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• 2014

We proposed a method for fast turn-off switching of a vertically-aligned liquid crystal cell by low-temperature curing of the polymer structure. We confirmed that the turn-off times of the fabricated cells were reduced significantly as the curing temperature was lowered to $-20^{\circ}C$. We accounted for the effect of low-temperature curing on the turn-off time by using a mathematical model and by observing images obtained via scanning electron microscopy. We also confirmed that low-temperature curing is more effective in reducing the response time when the device is operated at a low temperature.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.232-234
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• 2005

In this paper, A fuzzy logic based turn-off angle compensator for torque ripple reduction in a linear switched reluctance motor is proposed. The turn-off angle, as a complex function of motor speed and current, is automatically changed for a wide speed range to reduce torque ripple. Simulation results are presented that show ripple reduction when the turn-off angle compensator is used.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.428-432
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• 1998

A passive energy recovery snubber for high-power-factor boost rectifier, in which the main switch is implemented with a MOSFET, is described in terms of the equivalent circuits that are operational during turn-on and turn-off sequences. The main switch combined with proposed snubber can be turned on with zero current and turned off at limited voltage stress. The high-power-factor boost rectifier with proposed snubber is implemented, and the experimental results are presented to confirm the validity of proposed snubber.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1023_1024
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• 2009

In this paper, a novel 10kV, 50A, 50kHz pulsed power supply based on IGBT stacks is proposed. Proposed scheme consists of series connected 12 IGBT to generate maximum 10kV output pulse and 10kW full bridge phase-shifted zero voltage switching converter to charge DC capacitor voltage. Each IGBTs are sustain the 830V of capacitor voltage at turn off interval. By turn on the each IGBT for the same time it gives the path for the series connection of charged capacitor. From above turn on and off procedure, high voltage repetitive pulse is applied to the load. The synchronization of gating signal is important of series operation of IGBTs. For gating signal synchronization, specially designed gate power circuit using full bridge inverter and pulse transformer is developed to generate IGBT gating signal.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1061-1062
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• 2006

This paper represent improved On-line Turn off, commutation Angle control schemes for switched reluctance motors based on current control. For the purpose of the finding optimal commutation switching angle point, it is utilized turn on and turn off position calculation with inductance vs. current vs. flux linkage analysis method. The goal of proposed paper is the maximization of the energy conversion per stroke and maximizing efficiency and obtaining approximately flat-topped current waveform. The proposed control scheme is demonstrated on a simulation experimental result.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.177-180
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• 2020

This paper focuses on the 1,200-V level reverse conducting-insulated gate bipolar transistor (RC-IGBT). The structure of the RC-IGBT has an n+ collector at the collector terminal. The breakdown voltage, V_th, V_ce-sat, and turn-off time, and the electrical characteristics of a field-stop IGBT (FS-IGBT) and RC-IGBT are compared and analyzed using simulations. Based on the results, the RC-IGBT obtained a turn-off time of 320.6 ㎲ and a breakdown voltage of 1,720 V, while the FS-IGBT obtained a turn-off time of 742.2 ㎲ and a breakdown voltage of 1,440 V. Therefore, RC-IGBTs have faster on/off transitions and a higher breakdown voltage, which can reduce the size of the element.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.376-378
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• 1994

The turn-off behavior of the GTO Thyristor by its nature differs very much from that of other power f semiconductor switching devices. So canful attention should be paid in designing the GTO snubber circuit. This paper presents the effect of turn-off snubber circuit elements on the switching characteristics of the GTO, and describes considerations and criteria for the selection of the snubber component values.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1445-1453
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• 2017

In this study, a new zero-voltage transition (ZVT) buck converter with coupled inductor using a synchronous rectifier and a lossless clamp circuit is proposed. The regular buck converter with tapped inductor has extended duty cycle for high step-down applications. However, the leakage inductance of the coupled inductor produced considerable voltage spikes across the switch. A lossless clamp circuit is used in the proposed converter to overcome this problem. The freewheeling diode was replaced with a synchronous rectifier to reduce conduction losses in the proposed converter. ZVT conditions at turn-on and turn-off instants were provided for the main switch. The synchronous rectifier switch turned on under zero-voltage switching, and the auxiliary switch turn-on and turn-off were under zero-current condition. Experimental results of a 100 W-100 kHz prototype are provided to justify the validity of the theoretical analysis. Moreover, the conducted electromagnetic interference of the proposed converter is measured and compared with its hard-switching counterpart.