• 제목/요약/키워드: electromagnetic transient

검색결과 288건 처리시간 0.032초

차량 노면 진동을 이용한 공진형 선형 발전기 시스템의 강건최적설계 (Robust Optimum Design of Resonance Linear Electric Generator for Vehicle Suspension)

  • 최지현;김진호;박상신;서태원
    • 한국생산제조학회지
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    • 제23권4호
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    • pp.403-407
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    • 2014
  • To use vibration energy to generate electricity, a resonance vertical linear electric generator was applied to the suspension of a vehicle in a previous paper. However, the working conditions, including mass change in the vehicle body related to the cargo on board, number of passengers and the temperature difference caused by the operating environment, can influence the permanent magnet, which is the main component of the electric generator. Therefore, a robust optimum design is required to minimize the influences from the diverse operation conditions and maximize the electromotive force of the electric generator. In this paper, a resonance linear electric generator is introduced. Vibration response analysis to find the input velocity of the electric generator and an electromagnetic transient analysis to apply changes in the performance of the permanent magnet are performed. Finally, the optimum value of each design variable is derived using a Taguchi method.

초전도 한류기 투입저항 변화에 따른 여자돌입전류 저감률 분석 (Analysis of Inrush Current Reduction Rate According to Insertion Resistance of the Superconducting Fault Current Limiter)

  • 박세호;서훈철;이상봉;김철환;김재철;현옥배
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 제39회 하계학술대회
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    • pp.257-258
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    • 2008
  • The inrush current of a transformer is a high-magnitude and harmonic-rich current generated when the transformer core is driven into saturation during energizing. The inrush current usually leads to undesirable effects, for example potential damage to the transformer, misoperation of a protective relay, and power quality deterioration in the distribution power system. Inrush current reduction is therefore important for power system operation. In this paper, to reduce the inrush current, the insertion resistance of the Superconducting Fault Current Limiter (SFCL) that is connected in series with the transformer in the distribution system is used. This paper implements the SFCL by using the Electromagnetic Transient Program-Restructured Version (EMTP-RV) to model the SFCL in the distribution system. The simulation results show the beneficial effects of the SFCL for reduction of the inrush current.

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시간영역에서 수직 다이폴의 전파경로손실 특성 해석 (Characteristic Analysis on Radio Propagation Path Loss Characteristics of Vertical Electric Dipole in Time Domain)

  • 홍익표
    • 한국정보통신학회논문지
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    • 제17권7호
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    • pp.1558-1563
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    • 2013
  • 본 논문에서는 시간영역에서 완전도체 접지평면 위 수직 전기 다이폴에서 방사되는 전자기해석을 통해 전파의 거리에 따른 전파경로손실을 해석하였다. 자유공간에서 수직 전기 다이폴의 해석은 시간영역과 주파수영역에서 많은 연구가 이루어졌으나 본 논문에서는 특히 접지면 위 수직 다이폴을 기지국으로 가정한 전파경로손실특성을 시간영역에서 해석하였으며 접지면의 영향으로 나타나는 근접장의 위치변화와 모바일에서 수신되는 과도응답을 관찰하였다. 본 논문의 결과는 지표면 레이더 및 신호처리 분야에 응용될 수 있을 것이다.

공조용 압축기 축 거동 측정용 베어링 내장형 센서 (The built-in sensor bearing to measure shaft behavior of compressor for air-conditioning)

  • 김지운;안형준;김지영;한동철;윤정호;황인수
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 2001년도 제34회 추계학술대회 개최
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    • pp.230-236
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    • 2001
  • We developed a built-in sensor bearing to measure the rotor motion of a rolling piston type compressor for the air conditioner. Because of needs for the high efficiency and long life span of compressor, and the usage of alternative refrigerants, the operating condition of the compressor becomes more severe. The accurate measurement of the rotor motion of the compressor can contribute greatly to the design and analysis of the hydrodynamic bearing. However, it is difficult to measure accurately the shaft behavior of small compressor because of the small space for the sensor mount, high temperature and pressure of compressor, oil mixed with refrigerant, and electromagnetic noise of the motor. To overcome these difficulties, we develop the cylindrical capacitive sensor that is built in the hydrodynamic bearing and calibrate the built-in sensor bearing indirectly through measuring the oil relative permittivity. We measured the rotor motion as well as suction and discharge pressures in various conditions. The several experimental results show that the developed built-in sensor bearing can measure the rotor motion not only in steady state but also in transient state.

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레이저-GMA 하이브리드 용접에서 유동에 의한 기포 및 기공 형성 해석 (Numerical Simulation of Bubble and Pore Generations by Molten Metal Flow in Laser-GMA Hybrid Welding)

  • 조원익;조정호;조민현;이종봉;나석주
    • Journal of Welding and Joining
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    • 제26권6호
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    • pp.67-73
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    • 2008
  • Three-dimensional transient simulation of laser-GMA hybrid welding involving multiple physical phenomena is conducted neglecting the interaction effect of laser and arc heat sources. To reproduce the bubble and pore formations in welding process, a new bubble model is suggested and added to the established laser and arc welding models comprehending VOF, Gaussian laser and arc heat source, recoil pressure, arc pressure, electromagnetic force, surface tension, multiple reflection and Fresnel reflection models. Based on the models mentioned above, simulations of laser-GMA hybrid butt welding are carried out and besides the molten pool flow, top and back bead formations could be observed. In addition, the laser induced keyhole formation and bubble generation duo to keyhole collapse are investigated. The bubbles are ejected from the molten pool through its top and bottom regions. However, some of those are entrapped by solid-liquid interface and remained as pores. Those bubbles and pores are intensively generated when the absorption of laser power is largely reduced and consequently the full penetration changes to the partial penetration.

Critical Length Estimation of Counterpoise Subjected to Lightning Stroke Currents

  • Lee, Bok-Hee;Yoo, Yang-Woo;Kim, Jong-Ho
    • 조명전기설비학회논문지
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    • 제25권8호
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    • pp.106-113
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    • 2011
  • The conventional grounding impedance of a counterpoise is calculated as a function of the length of the counterpoise by use of the distributed parameter circuit model with an application of the EMTP(Electromagnetic Transient Program). The adequacy of the distributed parameter circuit model is examined and verified by comparison of the simulated and the measured results. The conventional grounding impedance of the counterpoise is analyzed for the first short stroke and subsequent short stroke currents. As a result, the simulated results show that the minimum conventional grounding impedance gives at a specified length of the counterpoise. The shorter the time taken to reach the peak of injected currents, the shorter the length of the counterpoise having the minimum conventional grounding impedance. We also present the critical lengths of the counterpoise for short stroke currents as a function of soil resistivity. Based on these results, it is necessary to compute the length of the counterpoise in a specified soil resistivity which satisfies both the low conventional grounding impedance requirement whilst also providing a suitable ground resistance in order to obtain an economical design and installation of the counterpoise.

The Overview of a Digital Power System Simulator for Large Power System Analysis

  • Kim, Tae-Kyun;Kim, Yong-Hak;Shin, Jeong-Hoon;Choo, Jin-Boo
    • KIEE International Transactions on Power Engineering
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    • 제3A권2호
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    • pp.93-99
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    • 2003
  • This paper deals with the development and testing of a large-scale, realtime digital power system simulator for the Korean Electric Power Corporation. The KEPS Simulation Center is located at KEPCO's research center (KEPRI) in Taejon, South Korea and has been operated since September 2001. The KEPS Simulation Center includes a wide range of off line power system simulation and analysis tools, as well as an advanced realtime digital simulator for the study of large scale AC and DC system performance. Because the application scope of the KEPS realtime simulator is broad and because the network models being considered are significantly larger and more complex than in traditional realtime simulator applications, many developments and tests have been required during the course of the project. In this paper, the authors describe some of these developments and present results from various benchmark tests that have been performed.

유한요소법을 이용한 전동지게차용 3상 유도전동기 특성 해석 연구 (The Study on the Characteristic Analysis of Three Phase Induction Motor For Electric Forklift Truck Using Finite Element Method)

  • 김광수;임종빈;이상훈;원성홍;구대현;이주
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2007년도 제38회 하계학술대회
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    • pp.1059-1060
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    • 2007
  • In this paper analysis of the characteristics in the three phase induction motor for the electric forklift truck is researched. There are two kinds of the Finite element analysis method. First thing is time domain analysis by the time transient method. Second thing is frequency domain analysis by method which assumes applied voltage and current sinusoidal. Especially in case of the characteristic studies, electromagnetic analysis is performed about each prototype motors. The obtained results are compared and the result of the test is examined. We could know characteristics of each prototypes and verify the design program of the motor through FEM. Finally this paper shows the factors of discord results of the analysis.

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대전력 시험전압 측정방법에 대한 고찰 (The study of test voltage measuring system for high-power testing laboratory)

  • 노창일;나대열;김선구;정흥수;김원만;이동준
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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    • pp.1038-1040
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    • 2005
  • This paper describes the optimal design, construction and performance evaluation of voltage divider used in high power testing laboratory for voltage measuring system. These dividers, which are of R, C, R&C type voltage dividers, the voltage to be measured range from voltage to several ten kilovolts, the frequency of the signals has a bandwidth from DC to megaHertz Measuring transient voltage and currents in the high voltage power laboratory is generally accompanied by electromagnetic interface and induced noise. above all, the measuring capabilities of voltage measuring system are dependent upon short response time and it must be as free as possible of inductive effects. In this paper presents both characteristic of voltage divider and design of voltage measuring system.

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Sensing and Vetoing Loud Transient Noises for the Gravitational-wave Detection

  • Jung, Pil-Jong;Kim, Keun-Young;Oh, John J.;Oh, Sang Hoon;Son, Edwin J.;Kim, Young-Min
    • Journal of the Korean Physical Society
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    • 제73권9호
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    • pp.1197-1210
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    • 2018
  • Since the first detection of gravitational-wave (GW), GW150914, September 14th 2015, the multi-messenger astronomy added a new way of observing the Universe together with electromagnetic (EM) waves and neutrinos. After two years, GW together with its EM counterpart from binary neutron stars, GW170817 and GRB170817A, has been observed. The detection of GWs opened a new window of astronomy/astrophysics and will be an important messenger to understand the Universe. In this article, we briefly review the gravitational-wave and the astrophysical sources and introduce the basic principle of the laser interferometer as a gravitational-wave detector and its noise sources to understand how the gravitational-waves are detected in the laser interferometer. Finally, we summarize the search algorithms currently used in the gravitational-wave observatories and the detector characterization algorithms used to suppress noises and to monitor data quality in order to improve the reach of the astrophysical searches.