• Journal of Power Electronics
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• v.8 no.2
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• pp.148-155
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• 2008

In this paper, a cost-effective PDP driving circuit using the transformer network is proposed. Compared with the previous works, the half-bridge type energy recovery circuit recovers the reactive energy not to the capacitor but to the source. A single sustain board architecture removes the blocking switches which are placed on the discharge path in parallel, thus reducing the number of devices. A simple reset circuit generates the same waveforms as the previous approaches. The circuit configuration and modified driving waveforms are compared with the previous works. The validity of the proposed simplified driver is verified through tests using a 6-inch panel.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.369-373
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• 2010

Modem electronic circuits are of importance for the function of communication, traffic systems and security systems. An intentional threat to these systems could be of big casualties and economic disasters. This paper has shown damage effect of microcontroller device with coupling caused by UWB-HPEM(Ultra Wideband-High Power Electromagnetics). The UWB measurements were done at an Anechoic Chamber using a RADAN UWB voltage source, which can generate a transient impulse of about 180 kV. The susceptibility level for microcontroller has been assessed by effect of various operation line lengths. The results of susceptibility analysis has showed that the effect of the reset line length on the MT(Ma1function Threshold) is larger than the effect of the different line length(Data, Power, Clock). With the knowledge of these parameters electronic system can be designed exactly suitable concerning the system requirements. Based on the results, susceptibility of microcontroller can be applied to protection plan to elucidate the effects of microwaves on electronic equipment.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.1-9
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• 2010

This paper summarizes an education and training system for the auto-reclosing of power transmission system using a real time digital simulator. The system is developed to understand the principle of reclosing and the sequence of automatic reclosing schemes, and practice the effects of reclosing actions to power system in real-time simulator. This study is concentrated into the following two parts. One is the development of real time education and training system of automatic reclosing schemes. For this, we use the RTDS(real time digital simulator) and the actual digital protective relay. The mathematical relay model of RTDS and the actual distance relay which is equipped automatic reclosing function are also used. The other is the user friendly interface between trainee and trainer. The various interface displays are used for user handing and result display. The conditions of automatic reclosing which is a number of reclosing, reclosing dead time, reset time, and so on, can be changed by the user interface panel. A number of scenario cases are reserved for the education and training. Through the test, we verified that the proposed system can be effectively used to accomplish the education and training of automatic reclosing.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.527-532
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• 2012

Recently, in power system, even though the needs of protective IED(Intelligent Electronic Device) is highly increased, there are some problems in the field when use the IED. When the IED is in the fluctuated overload condition, because of the existing algorithm calculate the trip time only with the measured current of just previous measuring stage, the calculated trip time is not a proper value for the overload protection at this kind of condition, and when the load current fluctuate between overload and normal condition, because of the instantaneous reset characteristic of existing algorithm the IED dose not trip. And the non linear loads using power electronic elements seem to be increased. These non linear loads require a counterplan about various harmonics incoming to electric power systems. So we will give solutions about these problems.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.563-564
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• 2015

Recently, distributed generation using renewable energy resources have increased due to the limitation of conventional energy. To utilize these energy source effectively, a method of applying the energy storage system(ESS) in distribution system has been considered. In this paper, we simulated the one line-to-ground fault in power system with ESS. Based on these simulations, we analyzed the effect on Over Current Relay(OCR) operation. As a result, ESS operation modes result fault current fluctuation. Thus, OCR need to reset the pick up current. This paper analyze effect of ESS in distribution system according to OCR setting by using ElectroMagnetic Transient Program(EMTP).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.423-432
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• 2012

We design a control circuit that can switch input power between a rechargeable battery and a sensor communication device (mote) depending on the operating state of a solar cell as well as the active and sleep mode of a sensor MAC protocol. A mote that simply combines a solarcell and a rechargeable battery may die if there is not sunlight long. A battery is recharged if sunlight is sufficient and a device is in a sleep mode, and it supplies power if sunlight is low and the mote is in an active mode. A mote can switch its input power between solar cell and battery depending on the output level of a solar cell. During this switching, a mote may lose its state information due to the reset of a microprocessor by the transient power-off. A capacitor is used to cope with this phenomenon and also supplies power to a mote during a sleep mode. Experimental results show that the solar cell based mote operates in a very stable manner against the lack of sunlight long.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.64-73
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• 2001

This paper presents a Zero Voltage and Zero Current Switching (ZVZCS) 3-Level DC/DC converter. This converter overcomes the drawbacks presented by the conventional Zero Voltage Switching(ZVS) 3-Level converter, such as high circulating energy, severe parastic ringing on the rectifier diodes, and limited ZVS load range for the inner switches. The converter presented in this paper uses a phase shift control with a flying capacitor in the primary side to achieve ZVS for the outer switches. Additionally, the converter uses an energy recovery snubber to reset the primary current during the free-wheeling stage to achieve ZCS for the inner switches. The proposed converters are analyzed and verified on 6kW, 39kHz experimental prototype.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.376-377
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• 2010

In this paper, novel unidirectional auxiliary resonant commutated pole is proposed to improve the performance of zero-voltage soft-switching inverter. The proposed circuit keeps the advantages of the original soft-switching inverter, while providing more effective resetting capability in magnetizing current. Based on the advanced reset mechanism, auxiliary switches operate under a complete zero-current condition. The operating principle and steady-state analysis are presented theoretically, according to its operating modes. Accordingly, it proves the fact that the proposed unidirectional auxiliary resonant commutated pole breaks an unwanted magnetizing current loop effectively. The performance of the proposed circuit is verified by several simulation results.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2209-2211
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• 1999

본 논문은 새로운 방식의 리셋회로를 적용한 MPC(Magnetic Pulse Compressor)방식의 펄스파워 발생장치에 관한 것이다. 개발된 펄스파워 발생장치는 MPC를 구성하는 코아에 대하여 별도의 리셋회로를 구성할 필요가 없고, 리셋과정은 메인 파워가 전달될 때 이루어지도록 설계되어 있어서 코아의 체적을 최적화하고 시스템을 간단히 구현할 수 있는 장점이 있다. 스위칭 소자로서는 반도체 소자인 싸이리스터만을 채택하여 긴 수명과 높은 신뢰성을 기대할 수 있게 하였고, DSP를 이용한 Controller를 구현하여 출력전압의 크기와 주파수 변경을 가능하도록 하였다.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.168-171
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• 2005

The conception of the passive lossless snubber with the simpler is presented. Thus a necessity condition of the passive lossless soft switching converter with the simplest topology is directed. A novel passive regenerative snubber called soft snubber applied to a hard switching converter is proposed. The passive snubber consists of a snubber inductor, two snubber rectifiers, and a snubber capacitor. The losses are reduced by inserting a snubber inductor in the series path of the rectifier during it's turn off. It is so simple that can make energy reset or capacitor discharged directly without producing any current circulation. To show the superiority of this converter is verified through the experiment with a 640W, 100kHz prototype converter.