• 제목/요약/키워드: Square cylinder

검색결과 206건 처리시간 0.025초

Computation of unsteady wind loading on bluff bodies using a discrete vortex method

  • Taylor, I.J.;Vezza, M.
    • Wind and Structures
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    • 제2권4호
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    • pp.285-303
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    • 1999
  • A discrete vortex method (DVM) has been developed at the Department of Aerospace Engineering, University of Glasgow, to predict unsteady, incompressible, separated flows around closed bodies. The basis of the method is the discretisation of the vorticity field, rather than the velocity field, into a series of vortex particles that are free to move in the flow. This paper gives a brief description of the method and presents the results of calculations on static and transversely oscillating square section cylinders. The results demonstrate that the method successfully predicts the character of the flow field at different angles of incidence for the static case. Vortex lock-in around the resonance point is successfully captured in the oscillatory cases. It is concluded that the vortex method results show good agreement, both qualitatively and quantitatively, with results from various experimental data.

정전용량 탐침을 이용한 토양수분 측정장치 개발 (Developement of Soil Moisture Meter using Capacitance Probe)

  • 김기복;이남호;이종환;이승석
    • 한국농공학회:학술대회논문집
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    • 한국농공학회 2001년도 학술발표회 발표논문집
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    • pp.65-68
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    • 2001
  • This study was conducted to develop a soil moisture meter using capacitance probe. A parallel cylinder type capacitance probe (C-probe) was fabricated The 5 MHz of crystal oscillator was constructed to detect the capacitance change of the C-probe with moist soil. A third order polynomial regression model for volumetric water content having oscillation frequency changes at 5 MHz as independent variables presented the determination coefficient of 0.979 and root mean square error of $0.031\;cm^{3}cm^{3}$ for all soil samples. A prototype soil moisture meter consisting of the sample container, C-probe, oscillator, frequency counter and related signal procession units presented the correlation coefficient of 0.987 and the root mean square error of $0.032\;cm^{3}cm^{3}$ as compared with the oven drying method for unknown soil samples.

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600dpi 마스터 에프세타 렌즈 가공 및 성능에 관한 연구 (A Study on Processing and Performance of a 600dpi Master F-theta Lens)

  • 박용우;문성민;류성기
    • 한국기계가공학회지
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    • 제19권5호
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    • pp.1-7
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    • 2020
  • This study examines the processing and performance of an f-theta lens, one of the main components used in laser printer and laser scanning systems. To design an f-theta lens, the optical path of the components of the laser scanning unit f-theta lens, cylinder lens, and collimator lens must be identified. The goal after machining the master f-theta lens is to understand the optical properties, root mean square, and peak to valley.

사각 물체가 존재하는 밀폐계의 종횡비 변화에 따른 내부 자연대류 현상에 대한 수치적 연구 (Numerical Simulation of the Natural Convection in Horizontal Enclosure of Different Aspect Ratio with an Array of Square Cylinder)

  • 이재룡;하만영
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.109-114
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    • 2003
  • The physical model considered here is a horizontal layer of fluid heated below and cooled above with a periodic array of evenly spaced square cylinders placed at the center of the layer, whose aspect ratio here varies from unity to twelve. Periodic boundary condition is employed along the horizontal direction to allow for lateral freedom for the convection cells. Two-dimensional solution for unsteady natural convection is obtained using an accurate and efficient Chebyshev spectral multi-domain methodology for a given Rayleigh numbers of $10^{6}$.

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왕복운동을 하는 사각채널에서 가열벽면의 수가 열전달에 미치는 효과 (Effect of Number of Heating Walls on Heat Transfer in the Reciprocating Square Channel)

  • 김명호;배성택;안수환
    • Journal of Advanced Marine Engineering and Technology
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    • 제29권2호
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    • pp.161-167
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    • 2005
  • The improvements of the propulsive engine efficiencies could reduce the fuel consumption. Therefore. for a marine main diesel engine the substantial increase of stroke bore ratio. so that the engine speed can be significantly reduced in order to increase the Propulsive efficiency. As a typical example. a Sulzer RTA 60C engine has acylinder diameter of 600 mm and each cylinder is capable of delivering 2.369 kW in the speed range 91-114 rpm. In order to Provide basic data for thermal system of marine engine. this work performs an experimental study of heat transfer in a square channel with one rib-roughened wall under sin91e mode of reciprocating oscillation. A selection of heat transfer measurements illustrates the manner by which the reciprocating channel with two opposite heating walls has the higher heat transfer Performance than with four heating wall.

Effectiveness of different confining configurations of FRP jackets for concrete columns

  • Moretti, Marina L.
    • Structural Engineering and Mechanics
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    • 제72권2호
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    • pp.155-168
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    • 2019
  • This paper presents the results of an experimental investigation on the compressive strength of small scale concentrically axially loaded fiber-reinforced polymer (FRP) confined plain concrete columns, with cylinder concrete strength 19 MPa. For columns with circular (150-mm diameter) and square (150-mm side) cross sections wrapped with glass- and carbon-FRP sheets (GFRP and CFRP, respectively) applied with dry lay-up the effect of different jacket schemes and different overlap configurations on the confined characteristics is investigated. Test results indicate that the most cost effective jacket configuration among those tested is for one layer of CFRP, for both types of sections. In square sections the location of the lap length, either in the corner or along the side, does not seem to affect the confined performance. Furthermore, in circular sections, the presence of an extra wrap with FRP fibers parallel to the column's axis enhances the concrete strength proportionally to the axial rigidity of the FRP jacket. The recorded strains and the distributions of lateral confining pressures are discussed. Existing design equations are used to assess the lateral confining stresses and the confined concrete strength making use of the measured hoop strains.

전기 유변성 클러치를 이용한 회전관성체의 위치제어 (Angular Position Control of a Rotor with Electro-Rheological Clutch)

  • 고봉춘;심현해;김창호;김권희
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1998년도 제28회 추계학술대회
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    • pp.203-211
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    • 1998
  • ER clutch is a device using electro-rheological fluid which is one of so called intelligent materials. Power transmission behavior of an ER clutch can be controlled by electrical field applied tb the fluid. In this work, a new type of servomechanism is developed with two ER clutchs, driven by two electrical motors rotating in reverse directions. The concentric cylinder type ER clutch is operated by PID control. The system shows good angular position control characteristics with respect to sinusoidal and square inputs.

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저마찰 피스톤 패드의 압력특성에 관한 연구 (A Study on the Pressure Characteristics in Low-Friction Piston Pad)

  • 김청균;권영진
    • Tribology and Lubricants
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    • 제8권2호
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    • pp.73-79
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    • 1992
  • The pressure distribution between the piston pad and the cylinder wall is analyzed to reduce the friction and to get the dynamic stability in the low friction piston. The calculated results indicate that the rectangular pad may reduce the friction in comparison to the square one. And the low friction piston can be stabilized when the pressure difference between the top and bottom of the piston skirt is very small.

모서리 절단 효과로 인한 사각주상체의 공기력 특성변화 전산해석

  • 황규관
    • EDISON SW 활용 경진대회 논문집
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    • 제4회(2015년)
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    • pp.553-558
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    • 2015
  • 교량의 주탑, 초고층빌딩과 같이 세장비가 큰 대형구조물의 경우 풍하중에 취약한 특성을 지니고 있어서 바람에 의해 직각 방향으로 발산 진동하는 갤로핑(galloping) 현상이 발생하게 된다. 구조물의 진동을 억제하려는 방안으로 단면 형상에 변화를 주어 공기역학적 불안정성을 감소시키는 방법이 사용되고 있다. 본 논문에서는 Edison_CFD를 이용하여 모서리 절단부의 비율과 받음각에 따른 공기력 특성에 대한 전산해석을 수행하였다.

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