• 제목/요약/키워드: Dimensional Characteristics

검색결과 5,256건 처리시간 0.031초

기판 위에 분포된 발열블록 주위의 3차원 혼합대류 열전달 해석 (Analysis of Three-Dimensional Mixed Convection Flow About Uniformly Distributed Heat-Generating Blocks on a Conductive Wall)

  • 윤병택;최동형
    • 대한기계학회논문집B
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    • 제23권1호
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    • pp.1-11
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    • 1999
  • The three-dimensional laminar mixed convection flow between the conductive printed circuit boards. on which the heat generating rectangular blocks are uniformly distributed, has been examined in the present study. The flow and heat-transfer characteristics are assumed to be pseudo periodic in the streamwise direction and symmetric in the cross-stream direction. Using an algorithm of SIMPLER, the continuity equation. the Navier-Stokes equations and the energy equation are solved numerically in the three-dimensional domain Inside the channel. The convective derivative terms are discretized by the QUICK scheme to accurately capture the flow field. The flow and the heat transfer characteristics are thoroughly examined for various Re and Gr.

SVD를 기반으로 한 고차원 데이터 및 질의 집합의 생성 (An SVD-Based Approach for Generating High-Dimensional Data and Query Sets)

  • 김상욱
    • 정보기술과데이타베이스저널
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    • 제8권2호
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    • pp.91-101
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    • 2001
  • Previous research efforts on performance evaluation of multidimensional indexes typically have used synthetic data sets distributed uniformly or normally over multidimensional space. However, recent research research result has shown that these hinds of data sets hardly reflect the characteristics of multimedia database applications. In this paper, we discuss issues on generating high dimensional data and query sets for resolving the problem. We first identify the features of the data and query sets that are appropriate for fairly evaluating performances of multidimensional indexes, and then propose HDDQ_Gen(High-Dimensional Data and Query Generator) that satisfies such features. HDDQ_Gen supports the following features : (1) clustered distributions, (2) various object distributions in each cluster, (3) various cluster distributions, (4) various correlations among different dimensions, (5) query distributions depending on data distributions. Using these features, users are able to control tile distribution characteristics of data and query sets. Our contribution is fairly important in that HDDQ_Gen provides the benchmark environment evaluating multidimensional indexes correctly.

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지표면의 특성을 고려한 대기경계층내의 열수지 parameter 추정 -열수지 parameter를 이용한 중규모 순환의 수치예측- (Estimation of the Heat Budget Parameter in the Atmospheric Boundary Layer considering the Characteristics of Soil Surface)

  • 이화운;정유근
    • 한국환경과학회지
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    • 제5권6호
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    • pp.727-738
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    • 1996
  • An one dimensional atmosphere-canopy-soil interaction model is developed to estimate of the heat budget parameter in the atmospheric boundary layer. The canopy model is composed of the three balance equations of energy, temperature, moisture at ground surface and canopy layer with three independent variables of Tf(foliage temperature), Tg(ground temperature), and qg(ground specific humidity). The model was verilied by comparative study with OSUID(Oregon State University One Dimensional Model) proved in HAPEX-MOBILHY experiment. Also we applied this model in two dimensional land-sea breeze circulation. According to the results of this study, surface characteristics considering canopy acted importantly upon the simulation of meso-scale circulation. The factors which used in the numerical experiment are as follows ; the change for a sort of soil(sand and peat), the change for shielding factor, and the change for a kind of vegetation.

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CFD에 의한 2차원 후향계단에서의 재부착 유동특성에 관한 연구 (A Study on Flow Characteristics of Two-Dimensional Backward-Facing Step by CFD)

  • 최영도;이영호
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 1998년도 추계 학술대회논문집
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    • pp.127-132
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    • 1998
  • The present study is aimed to investigate flow characteristics of Two dimensional backward-facing step by numerical approach. A convection conservative difference scheme based upon SOLA algorithm is used for the solution of the two-dimensional incompressible Navier-Stokes equations to simulate the laminar, transitional and turbulent flow conditions at which the experimental data can be available for the backward-facing step. The twenty kinds of Reynolds number are used for the calculations. In an effort to demonstrate that the reported solutions are dependent on the mesh refinement, computations are performed on seven different meshes of uniformly increasing refinement. Also to investigate the result of inflow dependence, two kinds of the inflow profile are chosen for the laminar flow. As criterion of benchmarking the result of numerical simulation, reattachment length is used for the selected Reynolds numbers.

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2차원 채널 충돌제트에서 난류강도의 변화에 대한 유동 및 열전달 특성 (A Characteristics of Flow and Heat Transfer for Variation of Turbulence Intensity In the Two-Dimensional Channel Impinging Jet)

  • 윤순현;김동건;김문경
    • 대한기계학회논문집B
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    • 제23권6호
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    • pp.753-760
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    • 1999
  • Experiments were conducted to investigate the effect of the initial turbulent intensity on the flow and heat transfer characteristics for a two-dimensional impinging jet. A square rod was installed at the nozzle exit to increase initial turbulent intensity. A hot wire probe and thermochromic liquid crystal technique were used to measure the turbulent intensity and the surface temperature. All measurements were made over a range of nozzle-to-plate distance from 1 to 10 at Re=20,000. When the rod is not installed, the maximum stagnation point Nusselt number is occurred at H/B=9. A higher initial turbulent intensity enhanced the heat transfer on the surface. A correlation between stagnation point Nusselt number and turbulent intensity are presented.

Analysis of Transport Characteristics for FinFET Using Three Dimension Poisson's Equation

  • Jung, Hak-Kee;Han, Ji-Hyeong
    • Journal of information and communication convergence engineering
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    • 제7권3호
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    • pp.361-365
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    • 2009
  • This paper has been presented the transport characteristics of FinFET using the analytical potential model based on the Poisson's equation in subthreshold and threshold region. The threshold voltage is the most important factor of device design since threshold voltage decides ON/OFF of transistor. We have investigated the variations of threshold voltage and drain induced barrier lowing according to the variation of geometry such as the length, width and thickness of channel. The analytical potential model derived from the three dimensional Poisson's equation has been used since the channel electrostatics under threshold and subthreshold region is governed by the Poisson's equation. The appropriate boundary conditions for source/drain and gates has been also used to solve analytically the three dimensional Poisson's equation. Since the model is validated by comparing with the three dimensional numerical simulation, the subthreshold current is derived from this potential model. The threshold voltage is obtained from calculating the front gate bias when the drain current is $10^{-6}A$.

전기강판의 회전자계 하에서의 2차원 자계특성 측정 (Measurement of Two Dimensional Magnetic Properties of Electrical Steel Sheets under Rotating Magnetic Fields)

  • 음영환;홍선기;신판석;고창섭
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제55권12호
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    • pp.617-622
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    • 2006
  • It is necessary to measure precisely the magnetic characteristics of electrical steel sheets under rotating magnetic fields, to obtain an accurate numerical performance analysis of electric machines made of electrical steel sheets. In this paper, the two dimensional magnetic characteristics of an electrical steel sheet are measured and explained under rotating magnetic fields using a two-axes-excitation type single sheet tester (SST). Through experiments, the magnetic properties, under rotating magnetic fields, of a non-oriented and grain oriented electrical steel sheet were measured respectively. In addition, the iron losses due to not only the alternating magnetic fields, but also rotating magnetic fields were measured. These experimentally measured results can evidently be applied to the analysis of iron losses in electrical machines.

3차원 입체요소를 사용한 정밀 전자부품의 사출성형 해석 (Numerical Analysis for Injection Molding of Precision Electronics Parts Using Three-Dimensional Solid Elements)

  • 박근;박제현;최상련
    • 소성∙가공
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    • 제11권5호
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    • pp.414-422
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    • 2002
  • Most of numerical analyses for injection molding have been based on the Hele Shaw's approximation: two-dimensional flow analysis. In some cases, that approximation causes significant errors due to loss of geometrical information as well as simplification of the flow characteristics along the thickness direction. The present work covers numerical analyses of injection molding using three-dimensional solid elements. The accuracy of the analysis results has been verified through some numerical examples in comparison with the classical shell-based approach. The Proposed approach is then applied to predict product defects and to improve flow characteristics for a precision electronics part. In addition, design of experiment has been utilized in order to find the optimal process conditions for better product quality.

3차원 입체요소를 사용한 정밀 전자부품의 사출성형해석 (Numerical Analysis for Injection Molding of Precision Electronics Parts using Three-Dimensional Solid Elements)

  • 박근;박제현;최상련
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2002년도 금형가공 심포지엄
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    • pp.68-75
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    • 2002
  • Most of numerical analyses for injection molding have been based on the Hele Shaw's approximation: two-dimensional flow analysis. In some cases, that approximation causes significant errors due to loss of geometrical information as well as simplification of the flow characteristics along the thickness direction. The present work covers numerical analyses of injection molding using three-dimensional solid elements. The accuracy of the analysis results has been verified through some numerical examples in comparison with the classical shell-based approach. The proposed approach are then applied to predict product defects and to improve flow characteristics for a precision electronics part. In addition, design of experiment has been utilized in order to find the optimal process conditions for better product quality.

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다차원 스펙트럼 해석법을 이용한 엔진소음의 전달특성 규명에 관한 연구 (Identification of Transfer Characteristics of Engine Noise by Multi-Dimensional Spectral Analysis)

  • 김동규;송재은;백문열;오재응
    • 한국자동차공학회논문집
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    • 제4권3호
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    • pp.40-49
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    • 1996
  • With the advance of the standard of living, the demand on automobile goes beyond the simple transportion equipment, therefore the interior noise reduction has been the important factor for improvement of the ride quality. Idling noise is a major vehicle characteristic determining occupant comfort. In the present research two approaches for noise source identification based on theory for multi-input system have been investigated. The concept of the frequency response function and the multi-dimensional spectral analysis were used to estimated the spectra of the noise source.

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