• Title/Summary/Keyword: 수치계산

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Application Study of Design Fire Curves for Liquid Pool Fires in a Compartment (구획실 내 액체 풀화재에 대한 디자인 화재곡선 적용 연구)

  • Baek, Bitna;Oh, Chang Bo;Lee, Eui Ju;Nam, Dong-Gun
    • Fire Science and Engineering
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    • v.31 no.4
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    • pp.43-51
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    • 2017
  • In this study, new design fire curves were suggested for the utilization in fire simulations. Numerical simulations with the Fire Dynamics Simulator (FDS) were performed for the n-octane and n-heptane pool fires in the ISO 9705 compartment to evaluate the prediction performance of the previous quadratic, exponential design fire curves and newly suggested ones. The numerical results were compared with the experimental temperature and concentrations of $O_2$ and $CO_2$. The numerical results with the previous quadratic and exponential curves showed slow increase and decrease trend than experiments. However, the numerical results with the newly suggested 2 design fire curves showed more similar variation trend in temperature, $O_2$ and $CO_2$ concentrations than the quadratic and exponential curves. It was found that the newly suggested design fire curves can be possibly used in the numerical simulation of fires in a practical respect.

A Study on the Flow Characteristics around a Hull Form of Coast-Canal Going Pusher-Barge (연안-운하 연계수송용 푸셔-바지 선형주위의 유동특성에 관한 연구)

  • Kim, Sung-Yong;Lee, Young-Gill;Lee, Seung-Hee
    • Journal of the Society of Naval Architects of Korea
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    • v.38 no.1
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    • pp.9-26
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    • 2001
  • In this paper. the development of a pusher-barge hull form which enables the continuous transportation along the coast and canal is performed. For the design stage of the hull forms. these are developed for Kyungin canal which is will be drawn up as the next contribution project of the Korean government are adopted. The model tests for the designed ship are carried out in the Inha University Towing Tank and the numerical simulations are done with a finite difference method based on MAC scheme. At first, the experiments are performed with designed model ships from low speed to high speed including service speed(6knots) among the corresponding designed speed. Resistance characteristics of designed ships are compared with experimental results of other several pusher-barge hull shapes. Next, the numerical simulations are performed for three cases, that is pusher only, barge only and pusher-barge condition in the designed speed. Each calculations are carried out in deep and restricted water condition. The flow characteristics around hulls in the latter condition are compared with those in the former condition.

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Accelerated Numerical Computations of Antennas Using OpenMP, MPI, CUDA (OpenMP, MPI, CUDA를 이용한 안테나 수치 계산 가속화)

  • Cho, Yong-Heui
    • Proceedings of the Korea Contents Association Conference
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    • 2014.11a
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    • pp.41-42
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    • 2014
  • 대형 안테나 해석에서 큰 화두는 안테나 수치 계산 속도를 높이는 것이다. 현재 인기를 얻고 있는 병렬 처리 방식인 OpenMP, MPI, CUDA를 이용하여 안테나 수치 계산을 병렬화할 경우 발생하는 단점을 제시하고, 각 병렬 처리법의 장점도 소개한다.

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An Expermental and Numerical Study of Natural Convection in the Annuli between Horizontal Confocal Elliptic Cylinders (수평동심 환원사이의 환상공간에서의 자연대류에 관한 수치 및 실험적 연구)

  • Lee, J. H.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.6 no.2
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    • pp.160-168
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    • 1982
  • 수평으로 놓여진 2개의 동심타원 사이의 환상공간에서의 자연대류현상이 수치계산 및 실험적으로 연구되었다. 수치적 연구는 정상 2차원 층류유동영역에서 수행되었으며 유선 및 등온선이 구하여 졌다. 또한 특수한 경우로서 수평동심원 사이의 환상공간에 관한 기존연구와 비교하여 좋은 일치 를 보았다. 실험적 연구에서는 3개의 실험모델을 제작하였으며 마하젠더 간섭계에 의한 간섭사진 으로부터 등온선 분포를 얻었으며 아울러 유동에 관한 정보도 얻을 수 있었다. 실험과 수치계산 결과는 상당히 좋은 일치를 보였으며 기존 동심원환상공간에 편심율이 추가된 이론전개 및 수치 계산방법의 적합성을 알 수 있었고 이로서 환상공간에서의 자연대류에 관한 연구를 확장시켰다.

만기형 별의 SiO 메이저에 대한 1차원 수치계산

  • Yun, Yeong-Ju;Park, Yong-Seon
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.2
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    • pp.69.1-69.1
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    • 2010
  • 장주기 Mira 변광성의 외피층에서 발생하는 SiO 메이저에 대해 non-local한 1차원 수치계산 결과를 처음으로 제시한다. 별의 유체역학적인 맥동모델에서 얻은 시간에 따른 별 주위 가스의 속도, 온도, 밀도 분포를 사용하여 계산하였다. 임의의 속도장을 갖는 구형 분자운에서의 복사전달문제를 풀었던 이전 연구에서 개발한 수치계산코드를 이용하였고, 특정 구간에서 급격한 변화를 겪는 물리량을 잘 반영할 수 있도록 수정하였다. 또한 계산에 사용되는 거대희소행렬을 압축희소행렬로 변환하여 메모리를 절약하였고 비선형방정식의 자코비안을 해석적으로 구하여 계산속도를 향상시켰다. v=1, J=1-0, J=2-1과 v=2, J=1-0 SiO 메이저의 공간분포, 상대세기 등에 대해 이전의 LVG 모델을 이용한 연구결과와 정성적으로 비교 논의한다.

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Numerical Computation of Laminar Flow over a Backward Facing Step (Beckward Facing Step의 층류 유동 수치계산)

  • Van, Suck-Ho
    • Journal of Ocean Engineering and Technology
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    • v.7 no.2
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    • pp.150-161
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    • 1993
  • 원초변수를 이용한 Navier-Stokes 방정식의 수치계산기법을 개발하고, 이를 응용하여 backward facing step의 층류 유동을 계산하였다. 직교좌표계에서의 비압축성 Navier-Stokes방정식을 풀기위해 시간과 공간항을 2차 정도의 유한 차분을 사용하여 이산화하였고 비교차격자계를 사용하여 양해법으로 수치 계산하였다. 운동량방정식과 연속방정식으로 부터 유도된 압력방정식(pressure-poisson equation)을 이용하여 무발산 조건을 만족시켰ㄲ다. Backward facing step의 층류 유동을 100.$\leq$R$_e$$\leq$1000 범위에 대해서 수치 계산하였으며 실험결과와 잘 일치하는 결과를 구할 수 있었다. 특히 step뒤에서 생기는 박리구간의 길이는 다른 계산결과들보다 실험치에 가까운 값을 얻을 수 있었으며, Re가 600보다 클때는 위쪽 벽에 또 다른 박리 유동이 발생되는 현상이 예측되었다.

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An Experimental and Numerical Sutdy oft Restraint Effects of Deformation in Model Foundation(1) (연약지반의 변형억제 효과에 대한 2차원 모형실험 및 수치계산)

  • 박병기;남진희
    • Geotechnical Engineering
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    • v.6 no.3
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    • pp.53-64
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    • 1990
  • Load tests for ten small-scale foundation models combined with geotextile and sand mat were conducted to study the effect of geotextile, sand mat, and foundation types on deformation of foundation soils. In addition, the experimental results were compared with those obtained from numerical analysis using a software program. The main conclusions were summarized as follows : 1. The restraint effect on GIT is more outstanding on the lateral displacement than on the vertical one. 2. The only use of SIM has better effect for the restraint of lateral displacement than vertical ogle. 3. The use of both SIM and GIT are required for the restraint of lateral and vertical displacement.

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Numerical Analysis of 2D, Steady, Inviscid Transonic Flow Through Stationary Compressor Cascade (2차원 직선 정지 익렬에서의 비점성 천이음속유동에 관한 수치적 해석)

  • 최인환;이진호;조강래
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.14 no.5
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    • pp.1244-1253
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    • 1990
  • Time-Marching methods solving Euler equations are used for calculation of two-dimensional, steady, inviscid flow through a stationary compressor cascade. Calculation method is based on the Denton`s opposed difference scheme. A smoothing in the axial direction is used to increase the stability of solution. The computational grid consists of quadrilateral elements, one of which has four nodes at each corner and the grid points on the upper periodic boundaries are located one pitch away from those on the lower boundaries to satisfy the periodicity condition. Results of calculation show good agreement with other computational and experimental results, proving that the present method of calculation should be applied with confidence for the cascade flow with shock wave.

Scattering of a Normally Incident Monochromatic Light by Optically Active Concentric Double Cylinders: II. Numerical Result (광학활성 동축 이중 원통을 수직하게 비추는 단색 빛의 산란 : II. 수치 계산 결과)

  • Kim, Hyun-Woo;Kim, Jin-Seung
    • Korean Journal of Optics and Photonics
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    • v.20 no.6
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    • pp.375-380
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    • 2009
  • The scattering of a normally incident monochromatic light by optically active concentric double cylinders is studied by using a numerical method. A numerical code is developed on the basis of the analytical solutions, and the angular distributions of the intensity and the polarization of the scattered light are computed for some specific cases. The numerical code can be used to non-invasively determine the size, structure, and composition of a double cylinder with high accuracy by measuring the angular distribution of the scattered light by an experiment.

A CFD Study of the Supersonic Ejector-Pump Flows (초음속 이젝터 펌프 유동에 관한 수치해석)

  • 이영기;김희동;서태원
    • Journal of the Korean Society of Propulsion Engineers
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    • v.3 no.4
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    • pp.58-66
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    • 1999
  • The flow characteristics of supersonic ejectors is often subject to compressibility, unsteadiness and shock wave systems. The numerical works carried out thus far have been of one-dimensional analyses or some Computational Fluid Dynamics(CFD) which has been applied to only a very simplified configuration. For the design of effective ejector-pump systems the effects of secondary mass flow on the supersonic ejector flow should be fully understood. In the present work the supersonic ejector-pump flows with a secondary mass flow were simulated using CFD. A fully implicit finite volume scheme was applied to axisymmetric compressible Navier-Stokes equations. The standard two-equation turbulence model was employed to predict turbulent stresses. The results obtained showed that the flow characteristics of constant area mixing tube types were nearly independent of the secondary flow rate, but the flow fields of ejector system with the second-throat were strongly dependent on the secondary flow rate due to the effect of the back pressure near the primary nozzle exit.

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