• 제목/요약/키워드: Loss Factor

검색결과 2,760건 처리시간 0.044초

배전계통의 역률보상 콘덴서의 최적 위치 및 용량 산정 (The Optimal Condenser Position & Capacity for Power Factor Compensation in Distribution System)

  • 장정태;전영수
    • 대한전기학회논문지:전력기술부문A
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    • 제48권10호
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    • pp.1190-1197
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    • 1999
  • The management of power factor(PF) in the distribution line is treated according to the measurement a month about the feeder unit at the substation. In Korea, we have not researched into power factor in distribution system due to it's less weight. The reactive power in advanced countries is controlled automatically by the compensative condenser switch on/off under the monitoring. This paper first presents the optimal condenser position and proper capacity by lagrangue factor ${\lambda}_{Q}$ which is the line loss index about reactive power unit. Therefore, the largest ${\lambda}_{Q}$ node is the condenser injection point and we find out the best condenser capacity when the line loss is saturated by the moderation of condenser volume. By this method, we suggest 0.6% uprising PF by injection of 15 kVA condenser. Additionally, PF is analysed into 5 areas; large city, middle city, small city, farm village, fishing village by the use of Power Platform which is classified the same concept of the low load management in KEPCO. Two feeders of each area are selected by the worst results of PF in specified areas.

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새로운 고역률 승압형 AC-DC 컨버터의 입력전류 파형분석에 관한 연구 (A Study on Waveform Analysis of Input Current for Novel Boost AC-DC Converter of High Power Factor)

  • 곽동걸
    • 조명전기설비학회논문지
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    • 제19권8호
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    • pp.102-108
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    • 2005
  • 본 논문에서는 소프트 스위칭에 의한 새로운 고역률 승압형 AC-DC 컨버터가 제안되고 입력전류의 파형 및 고조파분석에 대해 상세히 해석된다. 시비율 일정의 전류불연속 제어에 의해 동작되는 제안된 컨버터의 입력전류는 교류 입력전압의 크기에 비례한 불연속적인 펄스열의 정현파 형태로 되어 입력역률을 개선시킨다. 또한 제안된 컨버터는 소프트 스위칭을 위한 공진동작에 의해 무손실 스너버 커패시터의 입력측 에너지 유입에 따른 역률증대의 효과를 가지며, 기존의 고역률 승압형 AC-DC 컨버터와 비교되어 입력전류의 수학적 분석과 컴퓨터 시뮬레이션, 실험결과 등에 의해 그 우수성이 입증된다.

GIS기반 무선 센서노드 배치에서 경로손실을 고려한 위치 보정 방법 (A Position Revision Method by Path-Loss Factor in GIS based Wireless Sensor Node Deployments)

  • 배명남;권혁종;강진아;이인환
    • Spatial Information Research
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    • 제19권6호
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    • pp.111-121
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    • 2011
  • 본 논문은 GIS를 기반으로 도시 무선 통신환경에서 지형 공간 요소를 활용하고, 전파 손실에 영향을 미치는 대표 간섭 요인을 고려한 무선 센서노드 배치 알고리즘을 제안하였다. 먼저, 경기도 고양시 일산의 주요 도로에서 전파 손실 실험을 수행하고, 얻어진 실험 결과는 지리정보 시스템으로 부터 추출 가능한 주변 환경 정보와의 상관관계를 정의하였다. 다음으로, 이의 활용을 통해 무선 센서노드의 무선 커버리지 결정 및 배치 시스템 구현에 필요한 세부 동작에 대해 기술하였다. 그 결과, 전파에 영향을 많이 미치는 건물이나 도로의 선형 구조의 반영을 통해, 5dB 이하의 오류 수준으로 경로손실을 평가할 수 있었다. 그리고 이를 기반으로 센서노드 배치를 보정할 수 있는 방법을 제시하였다.

범프 타입 포일 스러스트 베어링의 정하중 구조 강성 및 손실 계수 차이에 관한 실험적 연구 (On the Bearing-to-Bearing Variability in Experimentally Identified Structural Stiffnesses and Loss Factors of Bump-Type Foil Thrust Bearings under Static Loads)

  • 이성진;류근;정진희;류솔지
    • Tribology and Lubricants
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    • 제36권6호
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    • pp.332-341
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    • 2020
  • High-speed turbomachinery implements gas foil bearings (GFBs) due to their distinctive advantages, such as high efficiency, lesser part count, and lower weight. This paper provides the test results of the static structural stiffnesses and loss factors of bump-type foil thrust bearings with increasing preload and bearing deflection. The focus of the current work is to experimentally quantify variability in structural stiffnesses and loss factors among the four test thrust bearings with identical design values and material of the bump and top foil geometries using the same (open-source) fabrication method. A simple test setup, using a rigidly mounted non-rotating shaft and thrust disk, measures the bearing bump deflections with increasing static loads on the test bearing. The inner and outer diameters of the test bearings are 41 mm and 81 mm, respectively. The loss factor, best-representing energy dissipation in the test bearings, is estimated from the area inside the local hysteresis loop of the load versus the bearing deflection curve. The measurements show that structural stiffnesses and loss factors of the test bearings significantly rely on applied preloads and bearing deflections. Local structural stiffnesses of the test bearings increase with applied preloads but decrease with bearing deflections. Changes of loss factors are less sensitive to applied preloads and bearing deflections compared to those of structural stiffnesses. Up to 35% variability in static load structural stiffnesses is found between bearings, while up to 30% variability in loss factors is found between bearings.

연성 평판 진동에 대한 파워흐름해석법의 실험적 연구 (Experimental Study On Power Flow Analysis of Vibration of a Coupled Plate)

  • 이규형;길현권;황성국;홍석윤
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2006년도 추계학술대회논문집
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    • pp.797-800
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    • 2006
  • The power flow analysis(PFA) can be effectively used to predict structural vibration in medium-to-high frequency ranges. In this paper, vibration experiment has been performed to observe the analytical characteristics of the power flow analysis of the vibration of a plate. In the experiment, the loss factor of the plate and the input mobility at a source point have been measured. The data for the loss factor has been used as the input data to predict the vibration of the plate with PFA. The frequency response functions have been measured over the surface of the plate. The comparison between the experimental results and the predicted results for the frequency responsefunctionshasbeenperformed.

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고공 강하용 수직풍동의 개념설계에 관한 연구 (A Study on the Concept Design of Vertical Wind Tunnel for Skydiver)

  • 조환기
    • 한국항공운항학회지
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    • 제26권2호
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    • pp.83-90
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    • 2018
  • This paper describes a case study on the design factor analysis of vertical wind tunnel for skydiver's training or experiencing of paradropping exercise in the air. The case study of vertical wind tunnel design is to provide the knowledges on effects of parameter's variation when it is applied to overall or partial duct of tunnel circuit. The analysis of design parameters based on pressure loss are produced one by one through the tunnel components from the flight chamber because the wind tunnel must satisfy the requirement of flight chamber such as flow speed, quality and quantity. Results shows the various effects of parameter variation with pressure loss in the wind tunnel circuit. Pressure loss should be based on the determination of fan and power system which can be selected from market or new design.

비구속형 점탄성 제진층을 갖는 보의 제진층 길이 최적화 (Length Optimization for Unconstrained Visco-elastic Damping Layer of Beams)

  • 이두호;황우석
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 추계학술대회논문집
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    • pp.665-671
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    • 2003
  • Length of an unconstrained viscoelastic damping layer on beams is determined to maximize loss factor using a numerical search method. The fractional derivative model can describe damping characteristics of the viscoelastic damping material, and is used to represent nonlinearity of complex modulus with frequencies and temperatures. Equivalent flexural rigidity of the unconstrained beam is obtained using Ross, Ungar, Kerwin(RUK) equation. The loss factors of partially covered unconstrained beam are calculated by a modal strain energy method. Optimal lengths of the unconstrained viscoelastic damping layer of beams are obtained with respect to ambient temperatures and thickness ratios of beam and damping layer.

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온도 및 주파수 변화에 따른 프린트 배선기판의 유전특성 연구 (A Study on Dielectric Properties of Printed Circuit Board Materials with Variation of Frequency and Temperature)

  • 박종성;김종헌;이준웅
    • 한국전기전자재료학회논문지
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    • 제11권10호
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    • pp.773-777
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    • 1998
  • This paper presents the results of measured permittivity of PCB sheet material in the frequency range of 0.1 ~ 2[㎓] and temperature range of 25~ 85[>$^{\circ}C$]. Microstrip lines with different physical length are implemented to measure the attenuation and phase shift of the signals through these lines. The loss factor of glass-epoxy and teflon could by calculated with the measured dielectric constant and the attenuation. From the experiment, the glass-epoxy was more influenced by temperature and frequency than teflon. The average dielectric constants of glass-epoxy and teflon within the measured frequency range are 4.48 and 2.18, respectively.

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손실을 고려한 전력시장 균형점과 손실계수 적용에 대한 연구 (A Study on Electricity Market Equilibrium with Transmission Loss and Application of The Loss Factor)

  • 김상훈;이광호
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2007년도 제38회 하계학술대회
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    • pp.838-839
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    • 2007
  • 전력산업의 시장구조는 과점형태의 불완전 경쟁의 구조로 해석하는 것이 일반적이다. 또한 전기의 물리적 특성상 송전선로에서는 전력손실이 발생하게 되는데, 본 논문은 과점시장 모델로서 쿠르노(Cournot)모델을 사용하여 손실을 포함한 내쉬 균형점을 해석한다. 지역별 한계가격(Locational Marginal Price ; LMP)와는 달리 계통한계가격(System Marginal Price ; SMP)는 손실에 대한 가격신호를 시장에 반영하기 어렵기 때문에 손실과 함께 한계송전손실계수(Marginal Loss Factor ; MLF)를 적용하여 균형상태의 시장거래가치를 비교분석한다.

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SEA 파라미터(연성손실계수)를 이용한 선박의 진동 파워흐름해석 (Vibration Power Flow Analysis of Ship Structures Using SEA Parameter(Coupling Loss Factor))

  • 박영호;홍석윤;박도현;서성훈;길현권
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 추계학술대회논문집
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    • pp.291-300
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    • 2000
  • This paper proposes the new hybrid analysis of vibration in the medium to high frequency ranges including PFA and SEA concept. The core part of this method is the applications of coupling loss factor(CLF) instead of power transmission, reflection coefficients in boundary condition. This method shows very promising compared to the classical PFA for the various damping loss factors and wide ranges of frequencies. Besides this paper presents the applicable method in Power Flow Finite Element Method by forming the joint element matrix with CLF. These hybrid concepts are expected to improve SEA and PFA methods in vibration analysis.

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