• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.153-156
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• 2001

Maximum Power Point Tracking(MPPT) Is used in wind power generation systems to maximize wind power turbin output power, irrespective of wind speed conditions and of the load electrical characteristics. In this paper we do the equivalent modeling the mechanical energy of wind power turbine according to wind speed into the synchronous generator. We analyse the equivalent modeling output part of rectifier into DC/DC converter input part theoretically. We design a control algorithm for variable voltage according to wind speed intensity and density so that load voltage of chopper is controlled steadily using the maximum power point tracking(MPPT) control method. We analyse a battery charging characteristics and a charging circuit for power storage enabling the supply of stable power to the load. We design a system and do the modeling of it analytically so that it supplies a stable power to the load by constructing a DC-AC inverter point. Also we design a charging circuit usable in actual wind power generation system of 30kW and confirm its validity.

• Journal of Radiation Protection and Research
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• 제48권3호
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• pp.124-130
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• 2023

Background: When bipolar junction transistors (BJTs) are used as switches, their switching characteristics can be deteriorated because the recombination time of the minority carriers is long during turn-off transient. When BJTs operate as low frequency switches, the power dissipation in the on-state is large. However, when BJTs operate as high frequency switches, the power dissipation during switching transients increases rapidly. Materials and Methods: When silicon (Si) BJTs are irradiated by fast neutrons, defects occur in the Si bulk, shortening the lifetime of the minority carriers. Fast neutron irradiation mainly creates displacement damage in the Si bulk rather than a total ionization dose effect. Defects caused by fast neutron irradiation shorten the lifetime of minority carriers of BJTs. Furthermore, these defects change the switching characteristics of BJTs. Results and Discussion: In this study, experimental results on the switching characteristics of a pnp Si BJT before and after fast neutron irradiation are presented. The results show that the switching characteristics are improved by fast neutron irradiation, but power dissipation in the on-state is large when the fast neutrons are irradiated excessively. Conclusion: The switching characteristics of a pnp Si BJT were improved by fast neutron irradiation.

• Journal of Power Electronics
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• 제2권2호
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• pp.124-129
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• 2002

Invertigation electromagnetic emissione of inverter power sources resistance welding existing special aspects of EMI measurements in the field of resistance welding machines resulting from the power rating and operation mode of these machines have to be taken into account. The characteristics of the internal switching processes determined by the behavior of the applied power semiconductors, sunbber circuits and constructional aspect exert a great influence on the conducted emission welding inverters.

• KEPCO Journal on Electric Power and Energy
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• 제6권4호
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• pp.433-438
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• 2020

Accurate forecasting of wind power is important for grid operation. Wind power has intermittent and nonlinear characteristics, which increases the uncertainty in wind power generation. In order to accurately predict wind power generation with high uncertainty, it is necessary to analyze the factors affecting wind power generation. In this paper, 6 factors out of 11 are selected for more accurate wind power generation forecast. These are wind speed, sine value of wind direction, cosine value of wind direction, local pressure, ground temperature, and history data of wind power generated.

• 조명전기설비학회논문지
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• 제23권12호
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• pp.90-95
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• 2009

배전계통에서 전력수요의 증가와 분산전원의 증가로 대용량 변압기의 적용이 불가피하게 되었다. 하지만, 대용량 변압기로 교체할 경우 배전계통에 고장발생시 고장전류의 크기가 증가되어 기존에 설치된 차단기 및 보호기기의 차단용량 초과로 인해 교체에 따른 경제적 비용 상승이 우려된다. 따라서, 대용량 변압기의 교체시 고장전류 증가 문제를 해결하기 위한 방안 중 하나로 초전도한류기를 설치하는 방안을 검토하고 있다. 하지만, 초전도한류기는 도입위치에 따라 ��치 발생 시 초전도한류기의 저항 크기가 다르게 되며, 이로 인해 고장전류 제한효과가 다르게 되며 기존의 보호 장치들의 동작에 영향을 주게 된다. 본 논문에서는 모의 배전계통에 초전도한류기를 적용하였을 경우 도입위치에 따라 전류제한효과를 포함하여, 모선 전압강하, 고장제거에 따른 초전도한류기의 회복특성을 실험을 통해 비교 분석하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.460_461
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• 2009

This paper analyzes the steady state characteristics for variable speed wind power system with doubly-fed induction generator(DFIG). This paper explains the equivalent circuit and phasor diagram of DFIG for different operating conditions. It also simulates the torque-slip characteristics with respect to changes of different parameters. Simulation results show the torque-slip characteristics, stator power factor-rotor voltage and stator current-rotor voltage.

• 한국전자통신학회논문지
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• 제10권8호
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• pp.945-952
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• 2015

GaN 전력증폭소자를 이용한 전력증폭기의 고효율 특성을 구현하기 위하여 $50{\Omega}$으로 정합된 전력증폭소자는 적용 주파수 대역, 출력전력, 효율 특성 선정의 한계가 있으므로 본 연구에서는 source/load-pull 시험을 통한 측정 데이터를 기반으로 고출력, 고효율 특성의 설계 목적에 맞는 정량적 입력 및 출력 임피던스를 추출하여 고효율 전력증폭기를 구현하였다. 구현된 전력증폭기는 2.7-3.1GHz의 주파수 대역에서 25watt(44dBm), 66-76%의 PAE특성 나타낸다.

• 동력기계공학회지
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• 제19권1호
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• pp.24-30
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• 2015

Geothermal energy is used in various types, such as power generation, direct use, and geothermal heat pumps. Geothermal energy with high temperature have been used for power generation for more than a century. The purpose of the study is to investigate flow and electricity power characteristics of hydraulic turbine for power generation of geothermal heat pump type with closed-system. The differences between the four types of hydraulic turbine, are different from the blade shape, volume, angle and etc. In case of prototype(1), pressure at blade was reduced to 2.1 bar, the kinetic energy of blade increased by increasing flow velocity(4.1 m/s). The increase of flow velocity at the blade edge markedly appeared, to increase the kinetic energy of the rotating shaft. In case that gateway in hydraulic turbine was installed, operating torque and RPM(1,080) of the rotating shaft increased respectively. Although rotational speed of prototype(2) compared to prototype(1) was reduced, the power generation capacity was greater about 3.4 times to 97 W. The most power of 255W was generated from prototype (4).

• 대한임베디드공학회논문지
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• 제11권6호
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• pp.379-392
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• 2016

This paper presents the design and simulation of a laser power beaming (LPB) system for an electric vehicle that establishes an optimal power transmission path based on the received signal strength. The LPB system is possible to transfer power from multiple transmitters to a single receiver according to the characteristics of the laser and the solar panel. When the laser beams of multiple transmitters aim at a solar panel at the same time, the received power is the sum of all energy at a solar panel. Our proposed LPB system consists of multiple transmitters and multiple receivers. The transmitter sends its power characteristics as optically coded pulses with a class 1 laser beam and powers as a high-intensity laser beam. By using the attenuated power level, the receiver can estimate the maximum receivable powers from the transmitters and select optimal transmitters. Throughout the simulation, we verified the possibility that different LPB receivers were achieved their required power by the optimal allocation of the transmitter among the various transmitters.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 추계종합학술대회
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• pp.758-761
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• 2003

전원장치의 소형화 핵심기술인 반도체 스위칭 기술을 이용하여 단일 전원을 사용하는 소형, 경량화 전자기기에 적합한 5 V/500 mA급 트랜스리스형 파워 모듈(transless type power module)을 설계하였다. 파워 모듈은 강압형 chopper 방식을 이용한 스위칭회로, 제어회로, 전압검출회로, 그리고 정전압 회로 둥으로 구성되어 있으며, 하이브리드-집적회로형(hybrid-IC type)으로 제작되었다. 본 연구에서 설계한 스위칭 레귤레이터 전원회로는 5 V/500 mA급 트랜스리스형 파워 모듈의 전기적 특성을 만족하였다.