• 전력전자학회논문지
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• 제19권1호
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• pp.23-30
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• 2014

This paper proposes a single power-conversion ac-dc converter with a dc-link capacitor-less and high power factor. The proposed converter is derived by integrating a full-bridge diode rectifier and a series-resonant active-clamp dc-dc converter. To obtain a high power factor without a power factor correction circuit, this paper proposes a suitable control algorithm for the proposed converter. The proposed converter provides single power-conversion by using the proposed control algorithm for both power factor correction and output control. Also, the active-clamp circuit clamps the surge voltage of switches and recycles the energy stored in the leakage inductance of the transformer. Moreover, it provides zero-voltage turn-on switching of the switches. Also, a series-resonant circuit of the output-voltage doubler removes the reverse-recovery problem of the output diodes. The proposed converter provides maximum power factor of 0.995 and maximum efficiency of 95.1% at the full-load. The operation principle of the converter is analyzed and verified. Experimental results for a 400W ac-dc converter at a constant switching frequency of 50kHz are obtained to show the performance of the proposed converter.

• Transactions on Electrical and Electronic Materials
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• 제14권5호
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• pp.235-241
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• 2013

A low power CMOS control circuit is applied in an integrated DC-DC buck converter. The integrated converter is composed of a feedback control circuit and power block with 0.35 ${\mu}m$ CMOS process. A current-sensing circuit is integrated with the sense-FET method in the control circuit. In the current-sensing circuit, a current-mirror is used for a voltage follower in order to reduce power consumption with a smaller chip-size. The N-channel MOS acts as a switching device in the current-sensing circuit where the sensing FET is in parallel with the power MOSFET. The amplifier and comparator are designed to obtain a high gain and a fast transient time. The converter offers well-controlled output and accurately sensed inductor current. Simulation work shows that the current-sensing circuit is operated with an accuracy of higher than 90% and the transient time of the error amplifier is controlled within $75{\mu}sec$. The sensing current is in the range of a few hundred ${\mu}A$ at a frequency of 0.6~2 MHz and an input voltage of 3~5 V. The output voltage is obtained as expected with the ripple ratio within 1%.

• 한국신뢰성학회지:신뢰성응용연구
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• 제16권4호
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• pp.331-337
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• 2016

Purpose: The purpose of this study is the analysis of the failure mechanisms effect of circuit design characteristics of the ballast for LED Lamp Methods: Recently, electronic circuit of ballasts for LED lamp are being occurred on various failure mechanisms (whiskers, ion migration, heat dissipation problem, switching element damage) because electronic ballast circuit design characteristics are becoming more and more diverse. Results: we analysis failure mechanisms that occurs in accordance with the circuit design characteristics The ballast for LED lamp were divided into three different types (Type A, Type B, Type C) considering circuit design characteristics (thermal design, PCB patten spacing, element material) and it was experimented in the acceleration test conditions ($85^{\circ}C$, 85% R.H). Conclusion: We confirmed that failure mechanism of the ballast for LED Lamp had occurred differently in accordance with the circuit design characteristics.

• Transactions on Electrical and Electronic Materials
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• 제18권1호
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• pp.42-45
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• 2017

In this paper, a transformer type SFCL (superconducting fault current limiter) using an additional magnetically coupled circuit was suggested. Its transient fault current limiting characteristics, due to the winding direction of additional coupled circuit, were analyzed through fault current limiting tests. The suggested transformer type SFCL was composed of the primary winding, and one secondary winding wound on the same iron core together with an additional magnetically coupled circuit. That circuit consists of the other secondary winding together with the other SC (superconducting) element connected in parallel with its other secondary winding. As one of the effective design parameters to affect the transient fault current of the SFCL, the fault current limiting tests of the suggested SFCL were carried out considering the winding direction of its additional coupled circuit. It was confirmed that, through the analysis on the fault current tests of the SFCL, the quench sequence of two SC elements comprising the suggested SFCL could be adjusted by the winding direction of the additional coupled circuit.

• 한국전기전자재료학회논문지
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• 제13권4호
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• pp.273-279
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• 2000

Electrical repair method which has replaced laser repair method can replace defective cell by redundancy’s in the redundancy scheme of conventional high density memory. This electrical repair circuit consists of the antifuse program/read/latch circuits, a clock generator a negative voltage generator a power-up pulse circuit a special address mux and etc. The measured program voltage of made antifuses was 7.2~7.5V and the resistance of programmed antifuses was below 500 Ω. The period of clock generator was about 30 ns. The output voltage of a negative voltage generator was about 4.3 V and the current capacity was maximum 825 $mutextrm{A}$. An antifuse was programmed using by the electric potential difference between supply-voltage (3.3 V) and output voltage generator. The output pulse width of a power-up pulse circuit was 30 ns ~ 1$mutextrm{s}$ with the variation of power-up time. The programmed antifuse resistance required below 44 ㏀ from the simulation of antifuse program/read/latch circuit. Therefore the electrical repair circuit behaved safely and the yield of high densitymemory will be increased by using the circuit.

• 대한의용생체공학회:의공학회지
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• 제26권1호
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• pp.49-54
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• 2005

This paper presents a design of 1-channel active dry electrode module for EEG from one's forehead. The IA(instrumentation amplifier) circuit inside the module is based on the configuration sown on the paper MettingVanRijn et al. We analyze the IA circuit to find out the related equation, and then compare its simulated characteristic with the result obtained from the real active dry electrode circuit. With the active dry electrode and the wet(Ag/AgCI) electrode connected to the separated analog processing module on one's forehead at the same time, their real time and FFT outputs of EEG are examined for comparison. The active dry electrode module has advantages over the wet electrode and its analog processing module: 1) The size of the analog processing circuit of the active dry electrode module is smaller than that of existing EEG analog processing module; 2) the total cost required to make the proposed analog processing circuit is much lower than that of the existing circuit, since the designed circuit needs smaller parts; 3) the electrical characteristic is comparable to the general EEG analog processing module even if the designed module has simpler circuit configuration.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.227-227
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• 2009

To prevent such accidents, molded case circuit breakers with improved short-circuit current interrupting capacity are needed. This paper is focused on understanding the interrupting capability with respect to double contact structure and puffer assisted self quenching that are based on the shape of the contact system in the current molded case circuit breaker. The new arc quenching structure for increasing the interrupting capacity of molded case circuit breakers is investigated by simulation and experiment.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.601-604
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• 2004

In this paper, we propose a driving circuit that can be operated with a lower voltage than that of the conventional circuit without reducing the discharge voltage. the circuit proposed in this paper has a merit to improve the electrical characteristics because it can be composed of switching devices with low voltage. The operation and efficiency using real devices. The features of the circuit proposed in this paper are as follows; the power loss can be decreased by the use of low voltage, the cost if the driving circuit for PDP can be reduced by the use of switching devices operated with low voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.355-357
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• 1996

With the wide-spread use of rectifier in electronic equipments, such problems as electronic components failures or equipment disorders have been occurred due to current harmonics. To overcome these problems, power factor correction circuits employing boost converter have been used. The switching stress of boost converter can be reduced by snubber circuit. Recently, research activities in snubber circuits have been directed to energy recovery snubber for improving the efficiency of power converter. In this study, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The circuit operation is confirmed through simulation.

• 한국전자통신학회논문지
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• 제9권3호
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• pp.335-342
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• 2014

본 논문에서는 하이브리드 궤도회로(Hybrid Track Circuit : HTC)의 실용화를 위한 시험방법과 그 절차에 대하여 연구하였다. 침목이나 도상 등 다양하고 특수한 선로 환경과 RFID 태그와 리더기, 안테나 구조를 고려한 시험방법을 제시함으로서 하이브리드 궤도회로의 서울메트로 구간 시범설치와 고속열차 구간 적용 연구에 활용이 가능하다. 또한 하이브리드 궤도회로 개발 프로젝트의 산출물 간 인터페이스와 설치방법 및 시험절차 등 안전하고 신뢰성 높은 결과를 도출하기 위한 방법을 제시하였다.