• 제목/요약/키워드: LossFactor

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통계적 에너지 해석법을 이용한 소형 잔향실의 연성손실계수 측정 (Calculation of Coupling Loss Factor for Small reverberation cabin using Statistical Energy Analysis)

  • 김관주;김운경;윤태중;김정태
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.797-801
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    • 2003
  • The Statistical Energy Analysis is based on the power flow and the energy conservation between sub-systems, which enable the prediction of acoustic and structural vibration behavior in mid-high frequency ranges. This paper discusses the identification of SEA coupling loss factor parameters from experimental measurements of small reverberation chamber sound pressure levels and structural accelerations. As structural subsystems, steel plates with and without damping treatment are considered. Calculated CLFs were verified by both transmission loss values for air-borne CLF case and running SEA commercial software As a result, CLFs have shown a good agreement with those computed by software. Acoustical behavior of air-borne noise and structure-borne noise has been examined. which shows reasonable results, too.

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샌드위치 구조를 가지는 복합재의 손실계수 향상을 위한 설계 (Design for Improving the Loss Factor of Composite with Sandwich Structure)

  • 이창민;전관수;강동석;김병준;김종훈;강명환;서영수
    • 한국소음진동공학회논문집
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    • 제26권3호
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    • pp.235-241
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    • 2016
  • Underwater weapon system is required to structurally strong material, since as it is directly exposed to external shock. It should also be using the lightweight material in order to take advantage of buoyancy. Composite materials meet these requirements simultaneously. Particularly in the case of submarine, composite materials are widely used. It is important to have a high strength enough to be able to withstand external shock, but it is also important to attenuate it. In a method for the shock damping, viscoelastic damping materials are inserted between the high strength composite material as a sandwich structure. Shock attenuation can be evaluated in the loss factor. In ASTM(American Society of Testing Materials), evaluation method of the loss factor of cantilever specimens is specified. In this paper, mode tests of the cantilever are performed by the ASTM standard, in order to calculate the loss factor of the viscoelastic damping material by the specified expression. Further, for verifying of the calculated loss factor, mode test of compound beams is carried out. In addition, the characteristics of the material were analyzed the effect on the loss factor.

무손실 스너버 회로를 이용한 소프트 스위칭 강압형 고역률 컨버터 (Soft switching high power factor buck converter using loss less snubber circuit)

  • 구헌회;변영복;김성철;서기영;이현우
    • 전자공학회논문지S
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    • 제34S권6호
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    • pp.77-84
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    • 1997
  • buck type converter doesn't appear when an input voltag eis lower than an output voltage. This is the main reason the buck converter has not been used for high power factor converters. In this paper, soft switching high power factor buck converter is proposed. This converter is composed of diode rectifier, input capacitor can be small enough to filter input current, buck converter with loss less snubber circuit. Converter is operated in discontinous conduction mode, turn on of the switching device is a zero current switching (ZCS) and high powr factor input is obtianed. In addition, zero voltage switching (ZVS) at trun off is achieved and switching loss is reduced using loss less snubber circuit. The capacitor used in the snubber circuit raised output voltage. Therefore, proposed converter has higher output voltage and higher efficiency than conventional buck type converter at same duty factor in discontinous conduction mode operation. High power factro, efficiency, soft switching operation of proposed converter is veified by simulation using Pspice and experimental results.

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필지 단위 주경사장 산정 및 적용을 통한 범용토양유실공식 지형인자 산정 개선 연구 (A Study to Determine the Slope Length and Steepness Factor of Universal Soil Loss Equation with Determining and Adapting Major Slope Length at Field Scale)

  • 박윤식;박종윤;장원석;김종건
    • 한국농공학회논문집
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    • 제61권6호
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    • pp.55-65
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    • 2019
  • Universal Soil Loss Equation (USLE) is to estimate potential soil loss and has benefit in use with its simplicity. The equation is composed of five factors, one of the factors is the slope length and steepness factor (LS factor) that is for topographic property of fields to estimate potential soil loss. Since the USLE was developed, many equations to compute LS was suggested with field measurement. Nowadays the factor is often computed in GIS software with digital elevation model, however it was reported that the factor is very sensitive to the resolution of digital elevation model. In addition, the digital elevation model of high resolution less than 3 meter is required in small field application, however these inputs are not associate with the empirical models' backgrounds since the empirical models were derived in 22.1 meter field measurements. In the study, four equation to compute LS factor and two approaches to determine slope length and steepness were examined, and correction factor was suggested to provide reasonable precision in LS estimations. The correction factor is computed with field area and cell size of digital elevation model, thus the correction factor can be adapted in any USLE-based models using LS factor at field level.

RUSLE 기법을 이용한 경주지역의 토양침식 위험도 평가 (Risk Assessment of Soil Erosion in Gyeongju Using RUSLE Method)

  • 오정학;유주한;김경태;이우성
    • 환경영향평가
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    • 제20권3호
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    • pp.313-324
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    • 2011
  • The purpose of this study is to present the raw data for establishing the plan of top soil conservation in soil environment and preventing the soil loss by establishing the potential amount of soil loss using RUSLE. The results are as follows. To apply the RUSLE model, we calculated the potential amount of soil loss by using 5 factors; rainfall erosion factor(R), topographical factor(LS), soil erosion factor(K), land cover factor(C) and erosion control factor(P). The assessment map of soil loss was drawn up by classifying 5 grades. According to the soil loss estimation by the RUSLE, it showed that approximately 83.9% of the study area had relatively lower possibility of soil loss which was the 1 ton/ha in annual soil loss. Whereas, the 7.0% of the study area was defined as high risk area which was the 10 ton/ha in annual. Therefore, this area was needed that there was environment-friendly construction of farm land, improvement of cultivation environment and so forth. In future, if we will analyze the amount of soil loss of Gyeongju national park and Hyeongsan river watershed, we will offer the help to establishing the conservation plan of soil environment in Gyeongsangbuk-do.

사다리꼴 fin: 사각 fin과의 열손실 비교와 열손실에 미치는 경사요소의 효과 (Trapezoidal Fin : Comparison of Heat Loss with Rectangular Fin and the Effect of Slope Factor on the Heat Loss)

  • 강형석;윤세창
    • 산업기술연구
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    • 제21권A호
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    • pp.33-40
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    • 2001
  • Heat loss from the trapezoidal fins haying different upper side slope and that from a rectangular fin are investigated by the three dimensional analytic method. It is shown that the trapezoidal fins having different upper side slope become an approximate rectangular fin by inst adjusting the slope factor. The comparison of the heat loss between a rectangular fin and an approximate rectangular fin is represented as a function of the non-dimensional fin length, fin width and Biot number to make sure that the analysis on the trapezoidal fins having different upper side slope is countable. One of the results is that the relative value of heat loss between a rectangular fin and an approximate rectangular fin is less than 1.5% for given ranges of non-dimensional length and width in case of Bi = 0.1.

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쓰레기 관로운송 시스템의 운송에너지 손실에 관한 수치해석적 연구 (Computational Study of Energy Loss in a Pipe of Refuse Collecting System)

  • 이종길;최윤;홍기철;최영돈
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2009년도 하계학술발표대회 논문집
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    • pp.421-426
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    • 2009
  • This paper describes on energy loss in a pipe of refuse collecting system. Analysis energy loss in a pipe is the decisive factor in a design for refuse collecting system. From the analysis energy loss, we can determine the capacity of turbo blower. The flow characteristics in the pipe with the refuse bag are analyzed by three-dimensional Navier-Stokes analysis. The refuse bag is modeled using the actual measurement. We obtain friction factor by changing refuse bag's size and mixing ratio and Reynolds number. And From the result we calculate energy loss by using compressible flow analysis.

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현장조사를 통한 4대강 유역의 보전관리인자 산정 연구 (A Study to Define USLE P Factor from Field Survey in the Four Major Watersheds)

  • 유나영;신민환;서지연;박윤식;김종건
    • 한국농공학회논문집
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    • 제60권2호
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    • pp.37-44
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    • 2018
  • Universal soil loss equation (USLE) had been employed to estimate potential soil loss since it was developed from the statewide data measured and collected in the United States. The equation had an origin in average annual soil loss estimation though, it was modified or improved to provide better opportunities of soil loss estimation outside the United States. The equation has five factors, most studies modifying them to adapt regional status were focused on rainfall erosivity factor and cover management factor. While the conservation practice factor (USLE P factor) is to represent distinct features in agricultural fields, it is challenging to find studies regarding the factor improvements. Moreover, the factor is typically defined using slopes. The factor defining approach was suggested in the study, the approach is a step-by-step method allowing USLE P factor definition with given condition. The minimum condition is slope and field location to provide an opportunity for using in any GIS software and to reflect regionally distinct features. If watershed location, slope, crop type, and mulching type on furrows are given, detailed definition of the factors are possible. The approach was developed from field survey in South-Korea, it is expected to be used for potential soil loss using USLE in South-Korea.

PFC 스위칭 정류기에서 손실인자에 의한 내부손실과 효율분석에 관한 연구 (A Study on the Internal Loss and Efficiency Analysis by Loss Factors in PFC Switching Rectifier)

  • 안태영
    • 반도체디스플레이기술학회지
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    • 제23권2호
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    • pp.50-54
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    • 2024
  • In this paper, we propose a theoretical method to systematically analyze the power conversion efficiency of a single-phase PFC switching rectifier. Boost-type PFC was organized in order of highest correlation with load current using steady-state analysis results and introduced the concept of loss factor. The loss factors for each major element are summarized and presented in a table. This paper makes it easier to understand the internal loss and power conversion efficiency of the rectifier for loss factors. Lastly, to confirm the validity of the efficiency analysis results reflecting the loss factors, loss and efficiency analysis of the 2.5kW PFC rectifier was performed. The results were compared with data from a 2.5kW PFC circuit for evaluation. As a result, the usefulness of power conversion efficiency analysis reflecting the loss factors proposed in this paper was confirmed.

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다자유도 곡선 맞춤법과 RKU 기법을 이용한 점탄성 감쇠재의 탄성 및 손실계수 추정방법 연구 (Study of the Measurement of Young's Modulus and Loss Factor for a Viscoelastic Damping Material Using a Multi Degree of Freedom Curve Fitting Method and RKU Equation)

  • 민천홍;박한일;배수룡;전재진
    • 한국해양공학회지
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    • 제25권1호
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    • pp.67-72
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    • 2011
  • Offshore structures, such as a platform, a buoy, or a floating vessel, are exposed to several dynamic loads, and viscoelastic damping material is used to reduce the vibration of offshore structures. It is important to know the properties of viscoelastic materials because loss factor and Young's modulus of the viscoelastic damping material are dependent on frequency and temperature. In this study, an advanced technique for obtaining accurate loss factor and Young's modulus of the viscoelastic damping material is introduced based on a multi degree of freedom curve-fitting method and the RKU (Ross-Kerwin-Ungar) equations. The technique is based on a modified experimental procedure from ASTM E 756-04. Loss factor and Young's modulus of the viscoelastic damping material are measured for different temperatures by performing the test in a temperature-controlled vibration measurement room where temperature varies from 5 to 45 degrees Celsius.