• Nuclear Engineering and Technology
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• 제49권7호
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• pp.1388-1395
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• 2017

The Helically coiled tube Once-Through Steam Generator (H-OTSG) is a key piece of equipment for compact small reactors. The present study developed and verified a thermal-hydraulic design and performance analysis computer code for a countercurrent H-OTSG installed in a small pressurized water reactor. The H-OTSG is represented by one characteristic tube in the model. The secondary side of the H-OTSG is divided into single-phase liquid region, nucleate boiling region, postdryout region, and single-phase vapor region. Different heat transfer correlations and pressure drop correlations are reviewed and applied. To benchmark the developed physical models and the computer code, H-OTSGs developed in Marine Reactor X and System-integrated Modular Advanced ReacTor are simulated by the code, and the results are compared with the design data. The overall characteristics of heat transfer area, temperature distributions, and pressure drops calculated by the code showed general agreement with the published data. The thermal-hydraulic characteristics of a typical countercurrent H-OTSG are analyzed. It is demonstrated that the code can be utilized for design and performance analysis of an H-OTSG.

• Journal of Electrical Engineering and Technology
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• 제6권4호
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• pp.466-473
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• 2011

This paper proposes a protection algorithm for a wind turbine generator (WTG) in a large wind farm. To minimize the outage section, a protection relay for a WTG should operate instantaneously for an internal fault or a connected feeder fault, whereas the relay should not operate for an internal fault of another WTG connected to the same feeder or an adjacent feeder fault. In addition, the relay should operate with a delay for an inter-tie fault or a grid fault. An internal fault of another WTG connected to the same feeder or an adjacent feeder fault, where the relay should not operate, is determined based on the magnitude of the positive sequence current. To differentiate an internal fault or a connected feeder fault from an inter-tie fault or a grid fault, the phase angle of the negative sequence current is used to distinguish a fault type. The magnitude of the positive sequence current is then used to decide either instantaneous operation or delayed operation. The performance of the proposed algorithm is verified under various fault conditions with EMTP-RV generated data. The results indicate that the algorithm can successfully distinguish instantaneous operation, delayed operation, or non-operation depending on fault positions and types.

• Journal of Magnetics
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• 제17권1호
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• pp.19-26
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• 2012

This paper deals with the performance analysis and estimation of the electrical parameters of a permanent magnet synchronous generator (PMSG) for hydrokinetic energy conversion applications using vortex induced vibration (VIV). The analytical solutions for the magnetic fields produced by permanent magnets (PMs) and stator winding currents are obtained using a 2D polar coordinate system and a magnetic vector potential. An analytical expression for the 2D permeance is also derived, which takes into account stator skew effects. Based on these magnetic field solutions and the 2D permeance function, electrical circuit parameters such as the backemf constant and the air-gap inductance are obtained analytically. The performances of the PMSG are investigated using the estimated electrical circuit parameters and an equivalent circuit (EC). All analytical results are validated extensively using 2D finite element (FE) analyses. Experimental measurements for parameters such as the back-emf and inductance are also presented to confirm the analyses.

• 에너지공학
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• 제24권4호
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• pp.159-165
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• 2015

본 논문에서는 EMP 차폐를 위한 WBC 배열이 설치된 대형 비상발전기 연도의 최적형상을 결정하는 것을 목표로 연구를 진행하였다. 시뮬레이션은 WBC 배열의 외부관경이 800, 850, 900, 1050mm 및 1250mm를 대상으로 하였으며 기본연도와의 접속길이를 150, 300, 450 mm, 연도의 유속은 15, 20, 25m/s로 하였다. EMP 차폐를 위한 WBC 배열을 연도에 설치하는 경우 WBC 배열의 외부관경, Main 연도와의 접속길이가 배기가스 흐름에 큰 영향을 미치는 것으로 나타났다. WBC 배열의 외부관경이 1050, 1250mm이고 접속길이가 300, 450mm이면 도파관 배열에서 배기가스의 평균속도와 최고속도를 만족시키는 것으로 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2170-2172
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• 1999

A low energy large aperture(LELA) pulsed electron beam generator of a cold cathode type has been developed for environmental applications, for example, waste water cleaning, flue gas cleaning, and pasteurization etc. The operational principle is based on the emission of secondary electrons from cold cathode when ions in the plasma hit the cathode, which are accelerated toward exit window by the gradient of an electric potential. We have fabricated the LELA electron beam generator with the peak energy of 200keV and beam diameter of 200mm and obtained the large aperture electron beam in air. The electron beam current density has been investigated as a function of glow discharge current, accelerating voltage and radial distribution in front of the exit window foil. The plasma density and electron temperature have been measured in order to confirm the relation with the electron beam current density. We are going to upgrade the LELA electron beam generator in the electron energy, electron beam current and stability of operation for various applications.

• 한국태양에너지학회 논문집
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• 제23권4호
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• pp.37-43
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• 2003

The aim of this research is to study the feasibility of the solar(hot fluid) driven $NH_3/H_2O$ absorption chiller, made by re-manufacturing of Gas fired $NH_3/H_2O$ absorption chiller. This experimental study is performed with the temperature of the inlet hot fluid of generator. In order to determine the inlet temperature of the generator, which gives maximum COP, the experimental data are obtained with various hot fluid supply temperature in range of $130\sim170^{\circ}C$. Remodeled chiller is operated with periodical cooling effect, which due to mixture subcooled pool boiling, then the COP is evaluated in average. The maximum COP$(\sim0.36)$ is at $160^{\circ}C$. The temperature is stable operation temperature range of typical vacuum collector. It offers a feasibility of solar driven $NH_3/H_2O$ absorption chiller.

• 한국압력기기공학회 논문집
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• 제13권1호
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• pp.54-60
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• 2017

When a sudden rupture occurs in high energy lines, ejection of inner fluid with high temperature and pressure causes blast wave as well as thrust forces on the ruptured pipe itself. The present study is to examine pipe whip behaviors and blast wave phenomena under postulated pipe break conditions. In this context, typical numerical models were generated by taking a MSL (Main Steam Line) piping, a steam generator and containment building. Subsequently, numerical analyses were carried out by changing break locations; one is pipe whip analyses to assess displacements and stresses of the broken pipe due to the thrust force. The other is blast wave analyses to evaluate the broken pipe due to the blast wave by considering the pipe whip. As a result, the stress value of the steam generator increased by about 7~21% and von Mises stress of steam generator outlet nozzle exceeded the yield strength of the material. In the displacement results, rapid movement of pipe occurred at 0.1 sec due to the blast wave, and the maximum displacement increased by about 2~9%.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 춘계학술대회
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• pp.275-278
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• 2017

차량의 교류발전기는 성능 및 효율에 따라 자동차의 연비와 배기가스에 많은 영향을 준다. 효율을 개선시키고 연비를 향상시키려는 노력은 자동차업체및 업체를 중심으로 계속되고 있다. 본논문은 A교류 발전기의 설계절차를 정리하고 같은 크기의 교류발전기에서 출력을 최적화하는 인자를 발굴하여 실차의 조건에서 충방전 Simulation을 통해 Energy Balance를 검증하였다.

• 설비공학논문집
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• 제26권6호
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• pp.287-293
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• 2014

Internal combustion engines release 30~40% of the energy from fossil fuels into the atmosphere in the form of exhaust gases. By utilizing this waste heat, plenty of energy can be conserved in the auto industry. Thermoelectric generation is one way of transforming the energy from engine's exhaust gases into electricity in a vehicle. The thermoelectric generators located on the exhaust pipe have been developed for vehicle applications. Different experiments with thermoelectric generators have been conducted under various test conditions as following examples: hot gas temperature, hot gas mass flow rate, coolant temperature, and coolant mass flow rate. The experimental results have shown that the generated electrical power increases significantly with the temperature difference between the hot and the cold side of the thermoelectric generator and the gas flow rate of the hot-side heat exchanger. In addition, the gas temperature of the hot-side heat exchanger decreases with the length of the thermoelectric generator, especially at a low gas flow rate.

• 조명전기설비학회논문지
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• 제22권10호
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• pp.24-33
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• 2008

본 논문에서는 유한요소법(Finite Element Method)을 기반으로 하는 직접 구동형 영구자석 풍력발전기를 DEAS(Dynamic Encoding Algorithm for Searches)를 이용하여 연간 최대에너지 생산량(Annual Energy Production : AEP) 최대화를 목표로 최적설계 하였다. 특히, 풍력발전기의 전 운전영역을 고려하기 위하여 해당풍속에서의 통계적 확률밀도와 연간 운전시간을 적용하여 연간 최대에너지 생산량을 산정 하였으며, 여기서 발생한 과도한 해석수행 연산시간을 줄이기 위해서 전역 최적화 알고리즘인 DEAS를 적용하여 풍력발전기 최적설계를 수행하였다.