• 대한기계학회논문집 C: 기술과 교육
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• 제3권2호
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• pp.141-148
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• 2015

본 연구에서는 진공 차단기(Vacuum circuit breaker)의 동적 특성을 모사하기 위해 리커다인을 이용한 다물체 동역학 해석 모델이 개발 되었다. 진공 차단기는 VI(Vacuum interrupter)를 포함한 3 개의 주회로 부와, 구동 메커니즘을 포함한 기구부로 구성된다. 이 해석적 모델의 검증을 위해, 해석 결과와 실측을 통한 실험적 결과를 비교 하였다. 일반적으로, 원활한 사고 전류 차단을 위해서는 0.9~1.1m/s 의 차단속도(Opening velocity)가 필요하다. 차단 속도의 향상을 위해, 다구찌 기법을 이용하여 진공 차단기의 설계 변수 최적화를 수행하였다. 또한 향상된 차단기의 동적 특성을 검증하기 위해, 해석 결과와 개선된 샘플의 실험적 결과를 비교 분석 하였다.

• 한국전기전자재료학회논문지
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• 제25권9호
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• pp.686-691
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• 2012

In this paper, we designed a Chua's chaotic circuit using transcondcutor based nonlinear resistor. Proposed chaotic circuit consist of L, C, R and transcondcutor based Chua's diode. We performed SPICE simulation for chaotic dynamics such as time seriesform, frequency analysis and phase plane of the circuit. Chaotic dynamics of the circuit was analysed according to MOS size variation of the operational transconductance amplifier. Also, we performed SPICE circuit analysis for temperature dependance of the circuit. SPICE results showed that chaotic dynamics of the circuit varied according to the temperature variation and chaotic signals were generated in specific temperature conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.183-185
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• 2002

This paper proposes the test method for the testing of a RLC parallel circuit on the electronic circuit board. This method utilizes a guarding circuit and a phase detection circuit. The guarding circuit separates electrically the tested device or circuit from printed circuit board. Phase detector estimates the phase difference from two signals, voltage and current. This method computes R. L and C value from phase difference($\theta$) and impedance value(Z) obtained by enforcing two other frequence stimulus under the guarding state.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 1997년도 추계학술발표회논문집
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• pp.11-13
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• 1997

Abstract - An electronic starter using MOSFET has been designed to take advantage of ideal preheating and starting features which can extend the lifetime of fluorescent lamps. The preheating circuit of the developed electronic starter is consisted of four parts - afull-wave rectifier circuit, an FET switching circuit a timer circuit for the gate switching, and a circuit for end-of-life protection. The circuit is analyzed by using PSpice simulation, and is improved to give an appropriate starting-time through control of R-C time constant of the timer circuit. And the circuit is also provided with an end-of-life protection feature, which utilizes the negative resistance characteristics of a thermistor that is thermally linked to FET through a heatsink. This also protects the FET from any overheating problems. From the results of simulation it is possible to obtain an appropriate value on the starting time for proper ignition and also it is verified that the limit for resistance of the thermistor is dependant on the value of resistance is the timer circuit

• 센서학회지
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• 제20권6호
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• pp.375-381
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• 2011

Ionic polymer-metal composite(IPMC) consists of an ion conductive membrane plated by metallic electrodes on both surfaces. When it bends, a voltage is generated between two electrodes. Since IPMC is flexible and thin, it can be easily mounted on the various surfaces of a body. The present study investigates a sensor system using IPMC to effectively detect the bending angles applied on IPMC sensor. The paper evaluates several R and C circuit models that describe the physical composition of IPMC and selects the best model for the detection of angles. The circuit models implemented with a charge model describe the relationship between input bending angles and output voltages. The identification of R and C values was performed by minimizing the error between the real output voltages and the simulated output voltages from the circuit models of IPMC sensor. Then the output signal of a sensor was fed into the inverse model of the identified model to reproduce the bending angles. In order to support the validation of the model, the output voltages from an arbitrary bending motion were also applied to the selected inverse model, which successfully reproduced the arbitrary bending motion.

• 한국통신학회논문지
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• 제22권2호
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• pp.318-324
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• 1997

Chua 회로는 간단한 전기 및 전자 회로를 구성하여 카오스 현상을 나타내는 회로로 자율, 3차계, 가역성(Reciprocal)이며 1개의 비션형 소자인 3구분 선형 저항과 4개의 선형 소자인 (R, L, $C_1,\;C_2$)로 구성되는 발진회로이다. 본 논문에서는 Chua 회로의 병렬 LC 공진기를 단락하여 시간 지연을 갖는 무손실 전송선로로 치환하고 특성 곡선법을 써서 파라미터 변화에 의한 카오스 운동과 주기운동이 있음을 위상공간과 분기도(Bifurcation diagram)로 확인 하였으며 무손실 전송선로가 원래의 Chua 회로와 유사한 어트렉터가 존재함을 확인하였다.

• 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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.707-710
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• 2002

A 120kV/70A high voltage switch has been installed at Korea Atomic Energy Research Institute in Taejon to supply power with Korea Superconducting Tokamak Advanced Research (KSTAR) Neutral Beam Injection (NBI) system. NBI system requires fast cutoff of the power supply voltage for protection of the grid when arc detected and fast turn-on the voltage for sustaining the beam current. Therefore the high voltage switch and arc current detection circuit are important part of the NBI power supply and there are much need for high voltage solid state switches in NBI system and a broad area of applications. This switch consisted of 100 series connected MOSFETs and adopted the proposed simple and reliable gate drive circuit without bias supply, Various results taken during the commissioning phase with a 100kW resistive load and NBI source are shown. This paper presents the detailed design of 120kV/70A high voltage MOSFETs switch and simple gate drive circuit. Problems with the high voltage switch and gate driver and solutions are also presented.

• 한국안전학회지
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• 제28권2호
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• pp.26-30
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• 2013

The purpose of this study is to find risk factors by analyzing the operation principle of a photo coupler (P/C) used to remove the noise of electronic devices and establish a base for the performance improvement of developed products. It was found from the P/C circuit analysis of normal products that they were equipped with an electrolytic condenser of $0.1{\mu}F$ to smooth system signals. Due to the epoxy resin packing the external part of the P/C, this study experienced a limit to visually examine the damage to it. It could be seen from the analysis of electric characteristics of the P/C that the forward voltage ($V_f$) and reverse current ($I_r$) were 1.3 V and 10 uA, respectively. In addition, it is required that the breakdown voltage (VCE) between the collector (C) and emitter (E) be maintained at less than 35 V. The and of the damaged product #1 were comparatively good. However, the measurement of was 100.0 uA. From this, it is thought that a short circuit occurred to the internal circuit. Moreover, from the fact that the of the damaged product #2 was open circuit and the measurement of was 0.0 uA, it is thought that the collector and emitter was separated or insulation resistance was significantly high. Furthermore, from the fact that the of the damaged product #3 was open circuit and the measurement of was 0.0 uA, it is thought that the space between the collector (C) and emitter (E) failed to meet the design standard or that they were separated. Therefore, it is thought that fabricating the P/C by increasing the reverse current 10 mA to 50 mA will prevent its malfunction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.808-810
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• 2002

Higher current-rating and improved thermal performance are being sought for existing medium-voltage vacuum circuit breakers(VCB) in order to meet market needs which require to be compact and downsized. In this paper, thermal performance of medium voltage vacuum circuit breaker was investigated through experiments and numerical analysis. We changed several major parameters of current-rating and heat sink affecting on thermal behaviors in the breaker and observed the results. To predict the temperature distribution in complex three-dimensional (3-D) VCB components and gas, the commercial package was used to simulate conjugate heat transfer. Although some assumptions and simplifications were introduced to simulate the model, results from the computational model were in good agreement with actual temperature rise measurements obtained from experiments.