• 제목/요약/키워드: Current spike

검색결과 90건 처리시간 0.027초

한국산 사초속 진퍼리사초절, 까락사초절과 괭이사초절에 관한 분류학적 연구 (A taxanomic study on sections Foetidae, Arenariae, and Multiflorae of Carex L. in Korea(Cyperaceae))

  • 오용자;김지혜
    • 식물분류학회지
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    • 제32권3호
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    • pp.257-292
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    • 2002
  • 한국산 사초속(Carex $Linn{\acute{e}}$) 괭이사초아속(Vignea Ness)의 진퍼리사초절(Foetidae Tuck.) 진퍼리사초(C. arenicola F. Schmidt), 까락사초절(Arenariae Kunth) 바위사초(C. lithophila Turcz.), 괭이사초절(Multiflorae Kunth) 괭이사초(C. neurocarpa Maxim.), 대구사초(C. paxii $K{\ddot{u}k$.), 산괭이사초(C. leiorhyncha C. A. Mey.), 애괭이사초(C. leaevissima Nakai), 양덕사초(C. stipata $M{\ddot{u}}hlenb$.), 도랭이사초(C. nubigena Don. var. albata (Boott) $K{\ddot{u}}k$. ex Masum.)을 대상으로 외부형태학적 형질을 재검토하였고 광학현미경과 주사전자현미경을 사용하여 과낭, 수과와 잎의 표피형을 조사하였다. 결과로 얻어진 정량적 형질(줄기, 잎, 이삭, 비늘조각, 총포 과낭과 수과의 길이 및 너비, 기공복합체의 크기와 빈도)과 정성적 형질(이삭, 비늘조각, 과낭과 수과의 모양, 엽설의 유무, 줄기단면과 비늘조각 윗부분의 모양 또한 과낭, 수과와 잎의 표피형, 기본표피 세포의 모양, 세포벽의 굴곡, 규소체의 모양, 부세포의 모양)이 종을 동정하는데 유용하였다. 본 연구의 결과 줄기, 잎, 포, 비늘조각, 과낭과 과낭부리의 길이와 너비, 줄기단면, 이삭, 과낭, 비늘조각 윗부분의 모양, 과낭 윗부분의 날개의 형태와 유무가 각 절을 구별할 수 있었고, 각 종의 동정에 유용한 형질이 되었다. 진퍼리사초절은 지하경이 옆으로 길게 기어가며 과낭의 날개가 없는 것이고, 까락사초절은 지하경이 옆으로 길게 기어가지만, 과낭에 날개가 있는 것으로 구분되었다. 괭이사초절은 지하경이 짧게 뭉쳐나며, 과낭에 날개가 있거나 없는 것이다. 진퍼리사초절에 속하는 진퍼리사초는 과낭의 날개가 없고, 과낭의 양쪽 끝에 톱니형의 날개가 있는 까락사초절의 바위사초(톱니형)는 괭이사초절과 큰 차이가 있다. 괭이사초절은 과낭에 날개가 있는 괭이사초(반톱니형), 대구사초(좁은형), 양덕사초(좁은형), 도랭이사초(좁은형)가 있으며, 날개가 없는 산괭이사초와 날개가 없거나, 드물게 좁은 날개가 있는 애괭이사초로 나눌수 있다. 이상의 결과로 절과 종 검색표를 정리하였다.

대전력 SCR 초퍼에서 가포하리액터-저항짝의 효과 (A Effect of Saturable Reactor-Resistor Pair on High Power SCR Chopper)

  • 강민구;조규형
    • 대한전기학회논문지
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    • 제37권7호
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    • pp.442-447
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    • 1988
  • Saturable reactor-resistor pair is proposed as a part of snubber and applied to a hard commutation chopper. SCR turn off process is modeled to simulate the hard commutation chopper. State equations are derived for each mode of the chopper and they are solved by Runge-Kutta 4th order method. It is shown that the reverse voltage spike and reverse dv/dt can be minimized by applying saturable reactor-resistor pair to the chopper which controls peak reverse recovery current and damping factor. Saturable reactor-resistor pair can be used to reduced SCR power loss and value of snubber capacitor and can be applied to high power thyristor devices.

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Design of A 2KW Soft-Switching ZVT Power Factor Correction Converter With Active Snubbers

  • Park, Kyoung-Soo;Kim, Yoon-Ho
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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    • pp.790-794
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    • 2001
  • In this paper a soft switching ZVT power factor converter using active snubbers is designed to improve efficiency and reduce voltage spike and parasitic ringing. The main switch achieves ZVT and the auxiliary switch performs with ZCS. A 2KW soft switching ZVT converter is designed with switching frequency 100kHz, output voltage 400VDC. Then the designed system is realized and experimental results show that the measured efficiency and power factor are over $97.45\%$ and 0.997 respectively with an input current THD less than $3\%$.

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미래의 사망가능성 감소에 대한 지불의사금액과 통계적 인간생명의 가치 측정 -환경적 피해와 환경정책의 평가를 위한 통계적 인간생명의 가치- (Estimating the Willingness-to-Pay and the Value of a Statistical Life for Future Mortality Risk Reduction : The Value of a Statistical Life for Assessing Environmental Damages and Policies)

  • 신영철;조승헌
    • 자원ㆍ환경경제연구
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    • 제12권1호
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    • pp.49-74
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    • 2003
  • This study used a slightly modified version of contingent valuation questionnaire designed and developed by Krupnick et al.(2000) to estimate the value of mortality risk reduction for environmental policy. Because that environmental policy, especially air pollution policy with some latency main effect on mortality risk reduction of old people with some latency period, respondents were asked about their current WTP for 5/1,000 mortality risk reduction being to take place beginning at 70 over the course of ten years. The annual mean WTP is 233,370 won (standard error 32,570 won) in spike/continuous/interval data model. The implied VSL is 466 million won. The 95% confidence interval is 339 million won~594 million won.

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Zero-Voltage Switching Dual Inductor-fed DC-DC Converter Integrated with Parallel Boost Converter

  • Seong, Hyun-Wook;Park, Ki-Bum;Moon, Gun-Woo;Youn, Myung-Joong
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2008년도 하계학술대회 논문집
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    • pp.523-525
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    • 2008
  • Novel zero-voltage switching(ZVS) dual inductor-fed DC-DC converter integrating a conventional dual inductor-fed boost converter(DIFBC) and a parallel bidirectional boost converter has been proposed. Most of current-fed type boost topologies including dual inductor schemes have crucial defects such as a high voltage spike on the main switch when it comes to turning off, an unattainable soft start-up due to the limited range of duty ratio, above 50%, and considerable switching losses due to the hard switching. By adding two auxiliary switches and an output capacitor on the conventional DIFBC, the proposed circuit can solve mentioned problems and improve the efficiency with simple methods. The operational principle and theoretical analysis of the proposed converter have been included. Experimental results based on a 42V input, 400V/1A output and 50kHz prototype are shown to verify the proposed scheme.

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An Isolated Soft-Switching Bidirectional Buck-Boost Inverter for Fuel Cell Applications

  • Zhang, Lianghua;Yang, Xu;Chen, Wenjie;Yao, Xiaofeng
    • Journal of Power Electronics
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    • 제10권3호
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    • pp.235-244
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    • 2010
  • This paper presents a new isolated soft-switching bidirectional buck-boost inverter for fuel cell applications. The buck-boost inverter combines an isolated DC-DC converter with a conventional inverter to implement buck-boost DC-DC and DC-AC conversion. The main switches achieve zero voltage switching and zero current switching by using a novel synchronous switching SVPWM and the volume of the transformer in the forward and fly-back mode is also minimized. This inverter is suitable for wide input voltage applications due to its high efficiency under all conditions. An active clamping circuit reduces the switch's spike voltage and regenerates the energy stored in the leakage inductance of the transformer; therefore, the overall efficiency is improved. This paper presents the operating principle, a theoretical analysis and design guidelines. Simulation and experimental results have validated the characteristics of the buck-boost inverter.

HID 램프의 스파이크 전류를 제어하기 위한 새로운 2단 전자식 안정기의 디지털 제어. (Digital control of a novel two-stage electronic ballast for spike current control of HID lamps)

  • 정우진;유창규;이우철
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2010년도 하계학술대회 논문집
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    • pp.212-213
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    • 2010
  • 본 논문에서는 고압 방전등을 위한 2단 저주파식 구형파 전자식 안정기를 제안한다. 안정기는 저주파수 구형파 전류를 램프에게 공급하기 위해 인버터와 PFC 단으로 이루어져 있다. 저주파수로 구동하기 때문에 음향 공진 현상은 발생하지 않는다. 그러나 저주파수 극성 반전시 스파이크 전류가 발생하게 되는데 램프전류에 더해져서 흐르기 때문에 램프의 정격 전력 특성에 나쁜 영향을 미치게 된다. 이에 대한 대책으로 새로운 제어 방식이 안정기를 제안하였다. 제안된 안정기는 HID 램프를 위해 150W의 프로토타입 안정기로부터 시뮬레이션 및 실험적인 결과들에 의해 검증하게 된다.

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최소 윈도우 기법을 이용한 강인한 지형 복원 (Robust Terrain Reconstruction Using Minimal Window Technique)

  • 김동규;우동민;이규원
    • 대한전기학회논문지:시스템및제어부문D
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    • 제52권3호
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    • pp.163-172
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    • 2003
  • A stereo matching has been an important tool for the reconstruction of 3D terrain. The current state of stereo matching technology has reached the level where a very elaborate DEM(Digital Elevation Map) can be obtained. However, there still exist many factors causing DEM error in stereo matching. This paper propose a new method to reduce the error caused by the lack of significant features in the correlation window The proposed algorithm keeps the correlation window as small as possible, as long as there is a significant feature in the window. Experimental results indicate that the proposed method increases the DEM accuracy by $72.65\%$ in the plain area and $41.96\%$ in the mountain area over the conventional scheme. Comparisons with Kanade's result show that the proposed method eliminates spike type of errors more efficiently than Kanade's adaptive window technique and produces reliable DEM.

능동 스너버를 갖는 2KW 소프트 스위칭 ZVT 역률 보정 컨버터 설계 (Design of A 2KW Soft-Switching ZVT Power Factor Correction Converter with Active Snubbers)

  • 박경수;김윤호;박경수
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2001년도 전력전자학술대회 논문집
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    • pp.677-680
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    • 2001
  • In this paper a soft switching ZVT power factor converter using active snubbers is designed to improve efficiency and reduce voltage spike and parastic ringing. The main switch achieves ZVT and the auxiliary switch performs with ZCS. A 2KW soft switching ZVT converter is designed with switching frequency 100kHz, output voltage 400VDC. Then the designed system is realized and experimental results shows that the measured efficiency and power factor were over $97.45\%$ and 0.997 respectively with an input current THD less than $3\%$.

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GTO 다이리스터의 미시적 모델링과 거시적 모델링에 의한 변환기 시뮬레이션 (Converter Simulation by the Micro Modeling and Macro Modeling of GTO Thyristor)

  • 서영수;백동현;김영춘;조문택;서수호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1993년도 하계학술대회 논문집 B
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    • pp.781-783
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    • 1993
  • The GTO model is based on the Ebers-Moll equation extened to include the three-junction devices and a detailed description of the implementation of the model equation as well as defferent tests are discussed. Problems to be considered for the snubber design, such as voltage spike reduction, maximum GTO anode current, and switching power, were discussed using the calculation model. The macro model is very useful for simulation of GTO circuit and high power circuit switch in high frequency and complex structure.

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