• 기계와재료
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• 제10권4호통권38호
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• pp.97-110
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• 1998

플라이휠 에너지 저장시스템은 입력되는 잉여전기에너지를 플라이휠의 관성을 이용, 회전 운동에너지로 변환하여 저장하고 필요시 전기에너지로 순시에 출력하는 장치로 배터리와 같은 화학적 에너지 저장장치에 대비되는 기계적 에너지 저장방식 (Electro-mechanical Battery)이다. 플라이휠 시스템은 많은 에너지를 단시간에 저장하고 이를 순발적으로 활용할 수 있는 고효율, 장수명, 무공해의 청정 에너지저장/재생장치로 선진국에서는 무공해 교통수단(전기자동차 등)의 차세대 보조 동력원을 비롯한 각종 민수용, 국방용으로 응용연구가 활발히 진행되고 있다(전력저장용, 인공위성의 태양광 에너지 저장 및 자세제어용, 무소음 적진침투용 차세대 전차의 보조동력원 등). 고효율의 에너지 저장 및 재생을 위해 플라이휠 에너지 저장시스템은 크게 .고속화, 고에너지저장을 위한 복합재 플리이휠 로터.공기 마찰손실 저감용 자가 진공펌프(Self Vacuuming system).지지부 접촉마찰로 인한 에너지 손실 저감용 자기베어링/제어부.플라이휠 구동 및 발전을 위한 Motor/generator.고효율 에너지 입출력 제어부 등의 첨단기술부품으로 구성되어 있는 바, 본 논문에서는 이러한 플라이휠 에너지 저장기술의 국내외 개발현황을 소개하고 현재까지 파악된 기술적 문제점 및 향후 기술개발 전망에 대해 논하고자 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.354-355
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• 2018

Flywheel energy storage system (FESS) operates motor or generator by utilizing the stored kinetic energy in the rotating mass. Thus, the FESS can support the frequency control of the power system. However, the FESS is disabled when the rotor speed reaches to its minium value. Thus, the second frequency dip occurs in the power system. This paper proposes the frequency control scheme of FESS based on a variable gain depending on the rotor speed and frequency deviation. The proposed scheme prevents the second frequency dip because the variable gain decreases depending on the stored in the FESS. The performance of the proposed scheme is investigated for the IEEE 14-bus system.

• 대한전기학회논문지:전력기술부문A
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• 제54권6호
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• pp.315-322
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• 2005

In this article, 1 would like to explore the estimation method of time-varying voltage sags in large industrial systems considering the short circuit contributions of rotating machines. For the power distribution system of KEPCO(Korea Electric Power Corporation), the magnitude of initial symmetrical short circuit current is generally not changed. However, in industrial systems which contain a number of rotating machines, the magnitude of voltage sag is generally changed from the initial to the clearing time of a fault due to the decreasing contribution of rotating machines for a fault current. The time-varying characteristics of voltage sags can be calculated using a short circuit analysis that is considered the time-varying fault currents. For this, the prediction formulations of time-varying voltage sags are proposed using a foreign standard. The proposed method contains the consideration of generator and motor effects. For the test of proposed formulations, a simple system of industrial consumer is used for the comparison conventional and proposed estimation method of voltage sag characteristics.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권4호
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• pp.161-169
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• 2003

The applications of SRM(Switched Reluctance motor) are dramatically increasing due to a simple mechanical structure, a high efficiency and a high speed drive characteristics. Energy recovery in the regenerative region is very important when SRM is used in traction drive. This is to reduce energy loss during mechanical braking and/or to have a high efficiency drive. To control excitation voltage during motoring and regenerating voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation. The proposed method is verified through simulations and experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
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• pp.184-190
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• 2005

The railway characteristic, which is concerned, as most utilities is unbalance produced by the large single-phase loads. Here are two theoretical concerns associated with unbalanced loads. First, generator rotor heating resulting from unbalanced current flow, Second, there is the possibility of motor overheating in industrial plants, due to the unbalanced voltage. Therefore, the exact assessment of the voltage unbalance must be carried out preferentially as well as load forecast at stages of designing and planning for the electric railway system. This paper proposes a new analysis model to more effectively estimate voltage unbalance. Numerous distributed circuits in the electric railway system are composed by components. The entire system can be easily modeled by the combination of four-port representation of each component in parallel and/or series. Simulation results using the model are compared with field data, and it verifies the accuracy of the proposed model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.568-570
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• 1995

Nowdays, voltage stability is well recognized as an important problem. It is well known that voltage stability is influenced by the characteristics of load. Up to present,voltage stability researches were done by the static load modeling, but it is needed that the precise analysis by the view point of dynamic load modeling. In this paper, with induction motor as dynamic load, using modal performance measure, optimal value of tcsc is determined.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.25-28
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• 2001

This paper introduce a millimeter-wave radar system. As Fig 1 shows, This system consists of millimeter-wave radar front-end and digital signal processing parts through receive waves regarding up-coming obstacles. The system works as follow process; (1) Generate regular tripodal waves using the FMCW pulse generator (2) Transmit/Receive waves regarding up-coming obstacles (3) Analog filtering (4) FIFO memory interface (5) FFT(Fast Fourier Transform) (6) Calculation of distance / speed between cars (7) Object display and calibration. We have progress to solve the problem like as increase of traffic accidents causing damage and injuries due to the increased number of motor vehicles and long distance driving, and Need for a device to help drivers who are in trouble due to bad weather conditions. We are expect to Take the lead as a core technology in the ITS industry and to develop circuit and signal processing technologies related to millimeter-wave bandwidth.

• 대한전기학회논문지:전력기술부문A
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• 제52권4호
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• pp.161-161
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• 2003

The applications of SRM(Switched Reluctance motor) are dramatically increasing due to a simple mechanical structure, a high efficiency and a high speed drive characteristics. Energy recovery in the regenerative region is very important when SRM is used in traction drive. This is to reduce energy loss during mechanical braking and/or to have a high efficiency drive. To control excitation voltage during motoring and regenerating voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation. The proposed method is verified through simulations and experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.337-339
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• 2001

High speed brushless permanent magnet (PM) machines are a key technology for electric drives and motion control systems for many application, since they are conductive to high efficiency, high power density small size and low weight. Proposed slotless PM machine is constructed without stator winding slots. Its stator magnetic material is in the form of a ring and winding have a toroidal configuration and its rotor consists of a 4-pole Halbach array or radially magnetized PM rotor.

• 전기학회논문지
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• 제58권9호
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• pp.1750-1756
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• 2009

In this paper, 5 kWh class Superconductor Flywheel Energy Storage System (SFES) was constructed including motor/generator, superconductor magnetic bearing(SMB), composite rotor and electromagnetic damper(EMD) system. High speed rotation test was performed after levitating flywheel rotor only using EMD without SMB. the PD controller of EMD was designed. the control system is constructed using xPC which is real time digital control system. the results of high speed rotation test showed that proposed EMD system have sufficient damping in cylindrical mode and conical mode, and vibration of wheel was suppressed below 10 ${\mu}m$.