• 전력전자학회논문지
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• 제3권1호
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• pp.70-76
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• 1998

본 연구에서는 고역률로 동작하면서 입력전류의 고조파성분을 크게 억제시키는 AC/DC 스위치모드 콘버어터의 기본적인 동작을 해석하고, 이를 기초로 수학적모델을 도출하여 전체 회로의 동작을 나타내는 모의실험방법을 제시한다. 제시된 모의실험모델로써 필터나 부스트인덕터 등의 회로구성요소의 정격을 결정하거나 정상 및 고장 운전조건하에서의 동작을 해석할 수 있음으로써 전체회로의 설계기준을 정할 수 있을 것이다. 모의실험결과가 실제 실험결과와 거의 일치함을 보임으로써 제시한 모의실험모델의 타당성을 입증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.203-203
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• 2010

The proton exchange membrane fuel cell (PEMFC) is different from the normal power supply, and it is a nonlinear, multi-input, strong coupling, the complex dynamic system with large time delay. At present, many studies on the content of the fuel cell fuel cells focus on a static process, this paper analyzed in subsequent sections of the process of fuel cell dynamic response time of transition, and then it found the method to reduce the response time during the process of load change to ensure that the stability of output power.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.693-696
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• 2005

We propose a robust adaptive fuzzy controller for the transient stability and voltage regulation of a single-machine inflnite bus power system. The proposed control scheme is based on the input-output linearization to eliminate the system nonlinearities. To deal with uncertainties due to a parameter variation or a fault, we introduce fuzzy systems with universal function approximating capability which estimate the uncertainties on-line.

• 설비공학논문집
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• 제13권6호
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• pp.514-523
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• 2001

The thermal performance characteristics of gas-loaded heat pipe(GLHP) were investigated by using transient diffuse-front model. Numerical evaluation of the GLHP is made with water as a working fluid and Nitrogen as control gas in the stainless steel tube. The transient vapor temperature and wall temperature were obtained. It is found that the temperature profiles and gas mole fraction distribution have been mainly influence by the diffusion between working fluid and noncondensable control gas in the condenser of GLHP. It is also found that he large power input make the diffusion region smaller.

• Journal of Advanced Marine Engineering and Technology
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• 제23권2호
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• pp.159-167
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• 1999

This paper presents a new transient voltage blocking device(TOBD)which low power and high frequency bandwidth to protect info-communication facilities from transient voltages. Conventional protection devices have some problems such as low frequency bandwidth low ener-gy capacity and high remnant voltage. in order to improve these limitations a hybrid type TOBD which consists of a gas tube avalanche diodes and junction type field effect transistor (JFETs) is developed. The TOBD differs from the conventional protection devices in configuration and JFETs are used as an active non-linear element and a high speed switching diode with low capacitance limited high current. Therefore the avalanche diode with low energy capacity are protected from the high current and the TOBD has a very small input capacitance. From the performance test using combination surge generator which can produce $1.2/50{\mu}m$ 4.2 kV/max, $8/20{\mu}m$ 2.1 kAmax it is confirmed that the proposed TOBD has an excellent protection per-formance in tight clamping voltage and limiting current characteristics.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.358-362
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• 1995

Precision electronic equipments are composed of sophisticated microcircuits that are extremely vulnerable to lightning-caused voltage spike. This transient voltage spike may cause upset, latent failure or interference on electronic equipments. In order to develop efficient lightning protection measures on AC power lines for a road traffic controller, experimental surge immunity tests were conducted according to IEC standard 801-5. The combination of gas tube arrester and metal-oxide varistor was installed at the input of AC power lines and the silicon avalanche suppressor installed at the output of DC power supply as lightning protection measures.

• 한국안전학회지
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• 제36권2호
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• pp.111-119
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• 2021

Multi-dimensional analysis of reactor safety-KINS standard (MARS-KS) is a thermal-hydraulic code to simulate multiple design basis accidents in reactors. The code has been essential to assess nuclear safety, but has mainly focused on light water reactors, which are in the majority in South Korea. Few previous studies considered pressurized heavy water reactor (PHWR) applications. To verify the code applicability for PHWRs, it is necessary to develop MARS-KS input decks under various transient conditions. This study proposes an input model to simulate small-break loss of coolant accidents for PHWRs. The input model includes major equipment and experimental conditions for test B9802. Calculation results for selected variables during steady-state closely follow test data within ±4%. We adopted the Henry-Fauske model to simulate break flow, with coefficients having similar trends to integrated break mass and trip time for the power supply. Transient calculation results for major thermal-hydraulic factors showed good agreement with experimental data, but further study is required to analyze heat transfer and void condensation inside steam generator u-tubes.

• Journal of Power Electronics
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• 제18권3호
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• pp.766-777
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• 2018

In this paper, a sliding mode and proportional plus integral (SM-PI) control combined with self-sustained phase shift modulation (SSPSM) for LLC resonant converters is presented. The proposed control scheme improves the transient response while preserving good steady-state performance. An averaged large signal model of an LLC converter with the ZVS modulation technique is developed for the SM control design. The sliding surface is obtained based on the input-output linearization concept. A system identification method is adopted to obtain the transform function of the LLC resonant converter, which is used to design the PI control. In order to reduce the inherent chattering problem in the steady state, the combined SM-PI control strategy is derived with fuzzy control, where the SM control is responsive during the transient state while the PI control prevails in the steady state. The combination of SSPSM and the SM-PI control provides ZVS operation, robustness and a fast transient response against step load variations. Simulation and experimental results validate the theoretical analysis and the attractive features of the proposed scheme.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.771-774
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• 2009

불규칙입력에너지 발전시스템에 이차여자 권선형 유도기를 적용하고 그의 해석에 대하여 다루었다. 불규칙적으로 변화하는 입력에너지에서 안정된 출력에너지를 얻기 위하여 시스템의 과도적 상태를 해석할 필요가 있다. 이에 본 연구에서는 교류기해석에 사용되는 2축 이론으로 1, 2차 측 전류, 전압, 출력 등 변수의 값을 해석할 수 있게 하였다. 최종적으로 전압전원형 인버터를 마이크로프로세서를 이용하여 안정된 출력을 얻는데 성공하였다.

• Journal of Biosystems Engineering
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• 제27권6호
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• pp.479-490
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• 2002

A dynamic model of a power shuttle transmission was developed and its validity was verified using the experimental data obtained from a transmission test bench. A 40㎾, 4WD tractor was also modeled using an application software EASY5 to investigate parameters and their effects on the power shifting performance. For a tractor model, the manual reverse gear was replaced by a power shuttle transmission. The tractor model also included an engine, main-gears for transmission, wheels, differentials and planet gears. Using the tractor model, the effects of the parameters such as modulating pressure and time, engine speed, tractor speed. tractor weight. reverse to forward speed ratio and torsional damper on the transient characteristics at starting and shuttle shifting were investigated by the computer simulation. The transient characteristics were represented by variations in clutch pressure, torque transmitted to input shaft and driving wheels, and power transmission capacity of the clutch. It was found that the modulating pressure and time affected most significantly the torque transmission and shifting time. The input torque, axle torque, power transmission capacity of the clutch and transmission time all increased with increase in engine speed, tractor speed. tractor weight and ratio of reverse to forward speeds. However, the axle torque decreased with tractor speed. Both the axle torque and power transmission capacity of the clutch also decreased with the ratio of reverse to forward speeds.