• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1816-1819
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• 2002

Nowadays, CO2 lasers are used widely in many applications such as materials fabrication, communications, remote sensing and military purpose etc. It is important to control the laser output power in those fields. In this paper, current resonant half-bridge inverter and Cockcraft-Walton circuit are used to vary the laser output power. This laser power supply is designed and fabricated which has less switching losses and compact size. Also we used an IGBT(Insulated Gate Bipolar Transistor) as a switching device of a power supply and PIC one-chip microprocessor are used to control the gate signal of the IGBT precisely. We investigated the output characteristics of this CO2 laser. As a result, the maximum laser output power of 26[W] is obtained at the resonant frequency of about 13[kHz].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.176-179
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• 2002

Nowadays, CO2 lasers are used widely in many applications such as materials fabrication. communications, remote sensing and military purpose etc. It is important to control the laser output power in those fields. In this paper, current resonant half-bridge inverter and Cockcraft-Walton circuit are used to vary the laser output power. This laser power supply is designed and fabricated which has less switching losses and compact size. Also we used an IGBT(insulated Gate Bipolar Transistor) as a switching device of a power supply and PIC one-chip microprocessor are used to control the gate signal of the IGBT precisely. We investigated the output characteristics of this CO2 laser. As a result. the maximum laser output power of 26 [W] is obtained at the resonant frequency of about 13 [kHz].

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.394-400
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• 2007

This thesis aims the development of power supply for the BTS of Mobile Telecommunication system. Specially, it receives AC power and it can be possible both supply the uninterrupted and stabile DC Power to BTS and simultaneously maintain full charging the back-up battery that is used in case failing AC power supply. In addition, easy maintenance is also the main purpose of it regardless of front and left side except rear side. In these days, it needs more small size power supply system in order to comply with the user needs regarding more easy maintenance and more less space as become smaller main telecommunication systems. This system can be installed close to wall and support more easy maintenance and it was considered easy expansion in case when it needs.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.222-223
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• 2013

본 논문은 Z-소스 능동전력필터를 이용하여 계통의 고조파를 보상하고 동시에 DC전원 공급이 가능한 능동전력필터를 제안하였다. 제안된 시스템은 Z-소스 네트워크 망에 의해 출력 전압의 여유가 있어 정상적인 보상이 힘든 출력 구간에서도 정상적으로 보상이 가능한 시스템이다. 제안된 방식은 시뮬레이션 및 실험을 통하여 타당성을 검증하였다.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1495-1502
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• 2017

The Theory of operation of switched reluctance motors (SRM) depends on the reluctance torque, where energy is transferred to stator winding only. Although its construction is simple, the electrical design is complex, due to the switching configuration needed to deliver power to stator coils. However, because of the nonlinearly of magnetic circuit, SRM has torque ripple. This paper proposes a new strategy to drive SRM from a single-phase AC supply. Each stator winding is connected to AC-DC or AC-AC converters, which is called branch. All branches are connected in parallel to a single-phase AC supply. A shaft encoder allows current production in stator winding during the positive torque production region and terminates it during the negative torque production region. A magnetic flux is produced between stator poles when current is supplied from AC supply to stator coil and repeats many cycles as long as the rate of change of stator inductance is positive. Different possibilities for the configurations of AC-AC or AC-DC converters are introduced to drive SRM from the single-phase AC supply. A case study is presented for a SRM fed from AC supply through semi-controlled AC-DC converter is presented. A simulation model is introduced and verified by experimental rig for two-phase SRM.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.236-238
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• 2012

본 논문은 저전력 데이터센터에 사용되는 DC 서버를 위한 고효율 DC UPS 결합형 전원분배장치의 구현과 설계에 관한 내용이다. 본 논문이 제안한 노드 준위 UPS 결합형 전원분배장치의 전력효율은 96%에 이르며 저전력 볼륨 서버의 전원공급장치(PSU)와 UPS를 대체할 수 있는 기술이다.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.5
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• pp.389-396
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• 2003

This paper describes a novel ac/dc power converter suitable for frequent output short-circuit faults. The output dc power of the proposed converter can be disconnected from the load within several hundred microseconds at the instant of short-circuit fault. The rising time of the dc load voltage is as small as several hundred microseconds, and there Is no overshoot of the dc voltage because the dc output fillet capacitors stay at a undischarged state. The proposed converter has the characteristics of a simplified structure, reduced cost, weight, and volume compared to the conventional power supplies for frequent output short-circuit. Analysis, simulations, and experiments are carried out to investigate the operation and usefulness of the proposed scheme.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.899-904
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• 2012

In recent years, a lot of research was done for earth fault protection in ungrounded dc power supply system. As a result, selective-breaking integrated protective relaying system is developed in progress and is currently field-testing are planned. Algorithm on a PC using PSCAD done a lot of testing before performing field tests, but in this study developed algorithms and functions needed to determine whether they were operating normally. Therefore, simulated system is similar to the actual situation was required and made. selective-breaking algorithm verification and validation was performed with simulator.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.192-194
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• 1998

This paper proposes a power supply for welding machine of reducing conduction Losses. To improve the conventional Phased-Shift FB DC-DC converter's problems that the copper loss in the high frequency transformer and conduction losses in the 1st terms bridge switch device because the leakage energy in the high frequency transformer and inducing of circulating current. This paper suggested a new topology of FB PWM DC-DC converter for welding machine to minimize a circulating current.

• Proceedings of the KIEE Conference
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• 2007.11b
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• pp.92-94
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• 2007

This article describes a thermoelectric converter, which is powered by thermoelectric (TE) power modules. This system uses TE devices that directly convert heat energy to electricity to power a converter using direct methanol fuel ceil (DMFC) system. The characteristics of the TE module were tested at different temperatures. A boost BC-DC converter was designed and controlled by a power-supply controller chip. Efficiency of about 80% can be achieved and because the thermoelectric converter system has not moving parts and has a small volume, the system can be carried about easily and conveniently to supply portable electric equipment and this is very important for some mobile equipment.