• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2668-2670
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• 2002

The generators of a small size below 100Kw are often used as power suppliers for emergency only in most domestic telecommunication companies. Serious twisted waves occur due to the inflow of harmonies from the generator into a S-type rectifier. And the increasing by stages of load upon the rectifier end up a stoppage of power supply during the serious hunting, which makes it difficult to supply power securely on the other part as well as that of communications. In case of long time of power failure the generators of a small size will be essential because the battery for emergency has a limit in capacity. Therefore it is necessary to solve the problems concerning the generators. This study is focused on the identifying and solving the problem including use of SCR elements connected to the generators.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.671-672
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• 2006

Recently the development of small hydropower generation with using water pipes is revitalized by the water works facilities. However, when the tubine generator is in case of emergency stop by the internal and external accidents, it causes water hammer in water pipes and suspension of water supply. To prevent these problems of small hydropower generator, we has analyzed water supply patterns, installation position and water pipe systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1005-1007
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• 2005

Small wind turbines are becoming a viable technology option to supply electricity to landowners. These systems provide energy security, product relatively no environmental harm, and in an appropriate setting can be quite cost-competitive with traditional electricity options. This paper is dealing with the methods how to overcome such inconvenience and with the analysis of characteristic and a field test with a prototype of the stand alone wind turbine was performed. The method applies to small systems, equipped with a coreless axial-flux permanent magnet(AFPM) generator in the turbine, a dc-dc converter and batteries. The analysis concentrates on the effect of the load on the power-wind speed curve of the turbine. The system is designed for direct driven, coupled with turbine and generator with a rated power of, 3kW.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.949-951
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• 2002

Permanent-magnet (PM) synchronous generator is feasible for use with a wind turbine, because the generator for wind power requires variable-speed generation, light weight, and high torque. In this paper, basic design and construction of an axial-flux permanentmagnet generator with power output at 60 [Hz], 300 [r/min] for wind energy system is introduced. Finite-element method (FEM) is applied to analyze generator performance. In order to save time, equivalent analysis model is developed. The performance of the proposed generator at no-load and resistive load are compared, and power output and voltage at various speed and loads are compared as well. The results of FE analysis show that this PM generator is a useful solution for small-scale wind-turbine applications.

• 전기학회논문지
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• 제58권5호
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• pp.929-935
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• 2009

As modem industrialized society progresses, the demand for electric power is increasing rapidly. The electric power system is getting amazingly bigger and complicated, which can easily induce serious troubles from the potential of large fault problems and/or system failure. The monitoring and diagnosis of the electric machine for the fault detection and protection has been important part in the electric power system. Most faults in the generator appear in the winding. This paper presents the air-gap magnetic flux characteristic of a small-scale 2-pole synchronous generator according to the faults in the field winding to protect the generator from the fault. The magnetic flux patterns in air-gap of a generator under various fault conditions as well as a normal state are simulated by using finite element method. These results are successfully applied to the detection and diagnosis of the short-circuit condition in rotor windings of a high capacitor generator.

• 대한방사선기술학회지:방사선기술과학
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• 제24권2호
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• pp.5-11
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• 2001

Most of X-ray generator had used rectifier type transformer with high tension generator which is supplied in a clinical diagnosis. Because the ripple rate of tube voltage is high, X-ray generating efficiency is very low. In these days, high tension generator for inverter type X-ray generator is being supplied from a broad which uses semi-conductor switching element for the electric power that have a high speed switching ability to solve these problem. But, semi-conductor element with large capacity is used with X-ray tube's large consumption power and diffusion is difficult in the small size hospital because production cost is going up by doing digital control through DSP. Therefore, this paper designed and manufactured CR type voltage divider for feedback control of tube voltage with high frequency resonance type inverter and for high tension transformer with high frequency. It was to make economical diffusion type X-ray generator which has wide output voltage and load extent. It was preyed that the X-ray generator had the stability of X-ray tube's output characteristics.

• 한국가스학회지
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• 제10권3호
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• pp.1-6
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• 2006

본 연구는 석탄을 가스화한 저발열량 합성가스 연료의 가스엔진과 소형가스발전기로의 적용가능성을 보여준다. 석탄을 가스화한 저발열량 합성가스를 가스엔진의 연료로 사용하기 위해 상용 LPG엔진을 부분적으로 변경하였다. 석탄가스화 연료에 적합한 연료공급시스템 -공기유량조절 오리피스, 가스믹서, 기화기, 예열히터, 레귤레이터, 연료탱크-이 집중적으로 변경되었다. 엔진 운전 결과에서 비록 석탄가스화 연료의 엔진 출력이 LPG연료에 비해 다소 떨어지지만 석탄가스화 연료를 사용하는 엔진이 공회전 조건에서부터 교축밸브를 완전 개방한 전부하조건까지 잘 운전됨을 보여주었다. 또한 본 연구에서 개발된 가스엔진발전기는 다양한 부하에서도 잘 작동됨을 보여주었다.

• 한국수소및신에너지학회논문집
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• 제23권3호
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• pp.236-242
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• 2012

This study has been carried out the experiment for the possibility of biogas reforming using waste heat. The source of this waste heat is the exhaust gas from a small-sized gas engine generator. For recovering the waste heat, Two-stage heat exchanger is manufactured. The two-stage heat exchanger is composed of a heat exchanger for the exhaust gas and a heat exchanger for the water. This two-stage heat exchanger is used for reforming the biogas by means of on-site hydrogen production at the small-sized gas engine generator. The two-stage heat exchanger is coupled with the biogas reformer which is a kind of catalytic reformer. To confirm a heat recovery efficiency of the two-stage heat exchanger, temperature differences of inlet and outlet locations are measured. Also, the variations of syngas concentrations with various biogas flow rates are investigated. As a result using manufactured two-stage heat exchanger, the biogas can be reformed from waste heat recovery. This experiment suggests that the exhaust gas heat exchanger is available for reforming the biogas.

• Journal of Advanced Marine Engineering and Technology
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• 제32권7호
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• pp.1044-1050
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• 2008

Most of developed countries, the consumption of fossil fuels has been serious problems that cause serious environment pollution like acid rain, global warming. Also, we have faced that limitation fossil fuels will be exhausted. Currently, small hydropower attracts attention because of its small, clean, renewable, and abundant energy resources to develop. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Tubular-turbine among small hydraulic power generation can be used at low-head. The purpose of this study is to research turbine's efficiency due to runner vane angle using CFD analysis.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.908-914
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• 2008

The world is facing a serious energy problem which destroying the environment. In addition, fossil fuel such as oil and coal that caused global warming and the environmental problems due to acid rain had been gradually exhausted. To solve this problem that has crisis of energy, it is necessary time and effort for research and development of renewable energy in the future. As alternative energy, small hydropower generation which has output of less or equal to 100kW is attracting considerable attention. This is because of its small, simple, renewable, and large amount of energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use reducing of a valve at the end of the pipeline, is collected by turbine in the small hydropower generator. In this study, we investigated the influence of the number of runner vanes on the characteristics of tubular-type hydroturbine.