• Title/Summary/Keyword: Experimental formula

검색결과 1,066건 처리시간 0.028초

철도에서의 선로용량 산정에 관한 연구 (Line Capacity Estimation in Railways)

  • 김동희;김봉선
    • 대한안전경영과학회:학술대회논문집
    • /
    • 대한안전경영과학회 2002년도 춘계학술대회
    • /
    • pp.257-262
    • /
    • 2002
  • There are two methodologies to increase transport capacity of railway. The one is to invest railroad equipment or vehicles, and the other is to improve operation efficiency through optimization. All of these is intended to increase transport capacity by improving line capacity So far, we treat line capacity as the criteria for evaluating investment alternatives or for restricting tram frequencies, and this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that change dynamically according to operational condition, so there is a need of new line capacity estimation system. The Purpose of this paper is to present a new line capacity estimation system based on the probability simulation and its applications.

  • PDF

프리캐스트 Girder-Beam 접합부에서 Girder Ledge의 전단내력에 관한 실험적 연구 (An Experimental Study on Shear Strength of Girder Ledge of Precast Girder-Beam Connection)

  • 배준우;박성무
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 1996년도 가을 학술발표회 논문집
    • /
    • pp.408-415
    • /
    • 1996
  • This study is aimed to define the behavior of the girder ledge of precast girder-beam joint in rame type precast concrete construction method. The variable of this study is followed : 1) The change of the maximum shear strength depended on the transformation of concrete compressive strength 2) The change of the behavior of ledge depended on the transformation of shear-span ratio 3) The change of maximum shear strength and ductility by the type of reinforcement. The results of this study show the behavior of ledge is affected by shear-span ratio and the maximum shear strength is depended on the concrete compressive strength, reinforcement ratio and effective section area. In addition, through the investigation of the established study, the results of this study suggest the shear friction formula of Raths.

  • PDF

Variability in bridge frequency induced by a parked vehicle

  • Chang, K.C.;Kim, C.W.;Borjigin, Sudanna
    • Smart Structures and Systems
    • /
    • 제13권5호
    • /
    • pp.755-773
    • /
    • 2014
  • The natural frequency of a bridge is an important parameter in many engineering applications such as bridge seismic design and modal-based bridge health monitoring. The natural frequency of a bridge vibrating alone may differ from that vibrating along with a vehicle. Although such vehicle-induced variability in bridge frequency is revealed in several experimental and numerical simulation studies, few attempts have been made on the theoretical descriptions. In this study, both theoretically and experimentally, the variability in the bridge frequency induced by a parked vehicle is verified, and is therefore suggested to be considered in bridge-related engineering, especially for those cases with near vehicle-bridge resonance conditions or with large vehicle-to-bridge mass ratios. Moreover, the variability ranges could be estimated by an analytical formula presented herein.

Inclination angle influence on noise of cavitating marine propeller

  • Bal, Sakir
    • Ocean Systems Engineering
    • /
    • 제10권1호
    • /
    • pp.49-65
    • /
    • 2020
  • In this study, the effects of inclined shaft angle on the hydro-acoustic performance of cavitating marine propellers are investigated by a numerical method developed before and Brown's empirical formula. The cavitating blades are represented by source and vortex elements. The cavity characteristics of the blades such as cavitation form, cavity volume, cavity length etc., are computed at a given cavitation number and at a set advance coefficient. A lifting surface method is applied for these calculations. The numerical lifting surface method is validated with experimental results of DTMB 4119 model benchmark propeller. After calculation of hydrodynamic characteristics of the cavitating propeller, noise spectrum and overall sound pressure level (OASPL) are computed by Brown's equation. This empirical equation is also validated with another numerical results found in the literature. The effects of inclined shaft angle on thrust coefficient, torque coefficient, efficiency and OASPL values are examined by a parametric study. By modifying the inclination angles of propeller, the thrust, torque, efficiency and OASPL are computed and compared with each other. The influence of the inclined shaft angle on cavity patterns on the blades are also discussed.

자계가속법에 의한 유도 전동기의 전력회생 구동 (Power Regenerating Drive of a Induction Motor by Field Acceleration Method)

  • 홍순일;홍정표;정승환
    • Journal of Advanced Marine Engineering and Technology
    • /
    • 제31권4호
    • /
    • pp.417-424
    • /
    • 2007
  • This paper presents a solution that an analytical model for an induction motor and the formula of regenerative power and instantaneous torque are derived. based on the spiral vector. The torque is controlled linearly through variations of the slip angular velocity, based on the field acceleration method (FAM). And also PWM inverter fed induction motor drives is schemed to be easily a regenerative drive. The voltage source inverter fed induction motor drives that regenerative power occurs with back current type is presented, to easily controlled the feedback power and to proper the adaption of energy shaving drives. The experimental tests verify the performance of the FAM, proving that food behavior of the drive is achieved in the transient and steady state operating condition, and are discussed to save the power that regenerative power is measured at the operating acceleration or deceleration of servo system.

접선유입식과 축상유입식 사이클론의 집진효율 비교 (Comparisons of Dust Collection Efficiency on the Tangental Entry and Axial-vane Type Cyclone)

  • 이중섭;이치우
    • 한국기계가공학회지
    • /
    • 제10권6호
    • /
    • pp.115-121
    • /
    • 2011
  • This study is about comparison of tangental entry type cyclone dust collector with axial vane type cyclone dust collector. Cut diameter and dust collection efficiency of both collector was compared by theory and experiment. Cut diameter was calculated by an quasi-empirical formula by Lapple and Shepherd. Measurement of cut diameter was conducted by particle counter through dust generator. As the result, cut diameter obtained by experiment was a little larger than that by theory. But the error is within $0.5{\mu}m$ in both type of collector, so it could be confirmed that theoretical value and experimental value were almost identical. And, as flow rate increased, dust collection efficiency was increased. Also axial vane type showed higher dust collection efficiency than tangental entry type. Therefore, it can be said that axial vane type cyclone dust collector has higher performance than the other.

철도투자 및 운영을 위한 용량분석에 관한 연구 (Capacity Analysis for the Railway Investment and Operation)

  • 김동희;홍순흠;김재희
    • 대한안전경영과학회:학술대회논문집
    • /
    • 대한안전경영과학회 2004년도 추계학술대회
    • /
    • pp.197-203
    • /
    • 2004
  • Railway system is consisted of various resources such as rail-line, signal, and railcar. It is necessary to efficiently utilize these limited and expensive resources as much as possible up to given line capacity. So far, we treat the line capacity as the criteria for evaluating investment alternatives or for restricting train frequencies, and this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that changes dynamically according to operational conditions, so there is a need of new line capacity estimation system. In this paper, we present an improved systematic line capacity model. The proposed model has three main components ; TPS(lain performance simulator), PES(parameter evaluation simulator), LCS(line capacity simulator). The concept of each sub-component is described, including the evaluation method of capacity parameters. And capacity parameter evaluation and estimation results using sample line section data are presented.

  • PDF

철도시스템 개선을 위한 용량분석에 관한 연구 (A Study on the Capacity Analysis for improving Railway Systems)

  • 김동희;김성호
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2003년도 춘계학술대회 논문집
    • /
    • pp.272-279
    • /
    • 2003
  • There are two methodologies to increase transport capacity of railway. One is to invest railroad equipment or vehicles, and the other is to improve operation efficiency through optimization. All of these is intended to increase transport capacity by improving the line capacity, So far, we treat the line capacity as the criteria for evaluating investment alternatives or for restricting train frequencies, and this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that changes dynamically according to operational conditions, so there is a need of new line capacity estimation system. Korea Railroad Research Institute(KRRI) proposed a new line capacity estimation system based on the probability simulation method. In this research. we perform analysis of line capacity for the railway improvement alternatives, and to represent the results.

  • PDF

확률실험에 의한 선로용량 추정체계에 관한 연구 (A study on the Estimation System of Line Capacity using Probability Simulation)

  • 김동희;홍순흠
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2002년도 춘계학술대회 논문집
    • /
    • pp.122-127
    • /
    • 2002
  • There are two methodologies to increase transport capacity of railway. The one is to invest railroad equipment or vehicles, and the other to improve operation efficiency through operation optimization. All of these is intended to increase transport capacity by improving line capacity. So far, we treat line capacity as the criteria for evaluating investment alternatives or for restricting train frequencies, and this criteria is calculated statical and experimental numerical formula. But, line capacity has special attribute that change dynamically according to operational condition, so there is a need of new line capacity estimation system. The Purpose of this paper is to present a new line capacity estimation system based on the probability simulation and its applications.

  • PDF

트란스레스 부전압 회로 (Transless Voltage Doubler)

  • 이영근;김성립
    • 대한전자공학회논문지
    • /
    • 제12권4호
    • /
    • pp.46-49
    • /
    • 1975
  • Mallory의 회로를 변형하여 변압기를 사용하지 않은 새로운 배전압회로를 구성하였고 직류출력전압의 regulation에 있어서 Mallory의 회로보다 훨씬 우수한 결과를 얻었다. 또 출력파형을 해석하고, 직류출력전압과 출력전류와의 관계를 간결한 반사식으로서 표현하였고 이 관계식이 실험결과와 잘 부합되어 있음을 보였다. In this paper, a new transless voltage doubler circuit which is a modification of Mallory circuit is proposed, Regulation characteristics of the new circuit is much superior to that of Mallory's. The analysis of output waveform is applied, an4 a simple and practical relation between dc output voltage and dc output current is derived. It is shown that this formula is coincide with the experimental results.

  • PDF