• 한국자동차공학회논문집
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• 제8권2호
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• pp.33-40
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• 2000

In order to investigate the exhaust structure and secondary oxidation of unburned hydrocarbon (HC) in the exhaust port, a numerical simulation was performed with 3-dimensional flow model and oxidation mechanism optimized for port oxidation. To predict the exhaust and oxidation process with consideration of flow, mixing, and temperature, 3-dimensional flow model and HC oxidation model were used with a commercial computational program, STAR-CD. The flow model were with moving grid for valve motion, which could predict the change of flow field with respect to valve lift. Optimization was performed to predict the HC oxidation with temperature range of 1200~1500K, low HC and oxygen concentration, existence of intermediate species, as typical in port oxidation. The constructed model could predict the port oxidation process with oxidation degree of 14~48% according to the engine operation conditions.

• Journal of Ship and Ocean Technology
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• 제5권4호
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• pp.44-50
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• 2001

Large container carriers are suffering from lack of knowledge on reliable correlation allowances between model tests and full-scale trials, especially at fully loaded condition, Careful full-scale sea trial with a full loading of containers both in holds and on decks was carried out to clarify it. Model test results were analyzed by different methods but with the same measuring data to figure out appropriated correlations factors for each analysis methods, Even if it is no doubt that model test technique is one of the most reliable tool to predict full scale powering performance, its assumptions and simplifications which have been applied on the course of data manipulation and analysis need a feedback from sea trial data for a fine tuning, so called correlation factor. It can be stated that the best correlation allowances at fully loaded condition for both 2-dimensional and 3-dimensional analysis methods are fecund through the careful sea trial results and relevant study on the large size container carriers.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.409-413
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• 2005

Even though the relative importance of length scale of flow system allow us to simplify three dimensional flow problem to one or two dimensional representation, many systems still require three dimensional analysis. The objective of this study is to develop an efficient and accurate finite element model for analyzing and predicting three dimensional flow features in natural rivers and to offend to model spreading of pollutants and transport of sediments in the future. Firstly, three dimensional Reynolds averaged Navier-Stokes equations with the hydrostatic pressure assumption in generalized curvilinear coordinates were combined with the kinematic free-surface condition. Secondly. to simulate realistic high Reynolds number flow, the model employed the Streamline Upwind/Petrov-Galerkin(SU/PG) scheme as a weighting function for the finite element method in conjunction with an appropriate turbulence model(Smagorinsky scheme for the horizontal plain and Mellor-Yamada scheme for the vertical direction). Several tests is performed for the purpose of validation and verification of the developed model. A simple rectangular channel, 5-shaped and U-shaped channel are used for tests and comparisons are made with RMA-10 model. Runs for each case is converged stably without a oscillation and calculated water-surface deformation, longitudinal and transversal velocities, and velocity vector fields are in good agreement with the results of RMA-10 model.

• 대한토목학회논문집
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• 제34권2호
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• pp.403-413
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• 2014

스트럿-타이 모델 방법을 이용한 콘크리트 구조부재의 설계 시 가장 중요한 요소 중 하나는 콘크리트 스트럿의 유효강도를 정확하게 결정하는 것이다. 콘크리트 스트럿의 유효강도를 결정하기 위한 많은 연구가 진행되어 왔으며, 여러 종류의 스트럿의 유효강도 값 및 산정식이 제안되었다. 그러나 이들은 2차원 콘크리트 구조부재의 스트럿-타이 모델 설계를 위한 것으로, 그 값을 3차원 콘크리트 구조부재의 설계에 적용하는 것은 적절하지 않다. 이 연구에서는 콘크리트 스트럿이 위치한 곳의 3축 응력 상태, 콘크리트의 3차원 파괴기준, 스트럿 길이의 영향, 스트럿과 압축 주응력 흐름과의 불일치의 영향, 콘크리트 압축강도의 영향, 그리고 철근에 의한 콘크리트 스트럿의 구속의 정도 등을 고려하여 3차원 콘크리트 스트럿의 유효강도를 일관성 있게 결정할 수 있는 방법을 제안하였다. 제안한 방법의 타당성을 검증하기 위해 기존 연구자들에 의해 파괴실험이 수행된 115개의 철근콘크리트 파일캡 시험체의 극한강도를 평가하였으며, 그 결과를 실험결과 및 현행 설계기준에서 제안한 스트럿의 유효강도 값을 이용하여 평가한 결과와 비교분석하였다.

• 대한기계학회논문집B
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• 제26권10호
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• pp.1436-1444
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• 2002

A three dimensional numerical model was developed to analyze the mold filling and solidification processes straightforwardly in a casting processes. On the basis of the SIMPLER algorithm, the VOF method and the Equivalent Specific Heat method were adopted to deal with the free surface behavior and the latent heat evolution. The complete model has been validated using exact solutions and experimental results. The importance of three-dimensional effects has been highlighted by comparing the results from the three-dimensional analysis with those given by a two-dimensional analysis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.396-399
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• 1995

In this study, Acquisition system is proposed to acquire 3 dimensional data of the free surface model using direct pulse control to machining center. Todo this, I/F to connect between manual operating handle and computer is made, and 3 dimensional shape measuring algorithm using Z-map is applied. The 3 dimensional shape data of the free surface model measured by laser displacement sensor and electric touch probe are achieved directly. Performance of the proposed system is evaluated through measurement of various shape model.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.405-408
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• 2004

The current design procedures of ACI 318-02, CE3-FIP and NZS 3101 for interior beam-column joints do not provide engineers with a clear understanding of the physical behavior of beam-column joints. In this paper, the failure strengths of the interior beam-column joint specimens tested to failure were evaluated using the 3-dimensional strut-tie model approach, design criteria of ACI 318-02, ACI-ASCE committee 352 and Park and paulay, and softened strut-tie model approach. The analysis results obtained from the 3-dimensional strut-tie model approach were compared with those obtained from the other approaches, and the validity of the approach implementing a 3-dimensional strut-tie model was examined.

• 산업기술연구
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• 제27권A호
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• pp.85-94
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• 2007

This study, regarding curved channel, was performed to compare and analyze hydraulic characteristics and the speed of water and water level for left bank and right bank through hydraulic model experiments and numerical analysis. Real channels that had characteristics of curved channel were selected as objectives. In order to easily operate one and two dimensional numerical analysis and comparison for total 2.4Km model channel, measuring point was set up as 200m. HEC-RAS model was applied as one dimensional numerical analysis program and SMS model was used as two dimensional numerical analysis program. In respect of speed of water, the average speed of water for right bank recorded 8.33m/s in a model experiment and 3.08m/s, 8.57m/s were average speed of water for right bank in one dimensional and two dimensional numerical analysis. The average speed of water of two dimensional numerical analysis was quite similar to that of model experiments. Also, as for water level, maximum observational errors between one and two dimensional numerical analysis for right and left bank of model experiments were 0.66m, 0.84m and 0.28m, 0.48m for each. It was found that two dimensional numerical analysis had a similar result to hydraulic model experiments. Accordingly, from the result of this study, two dimensional numerical analysis should be used rather than one dimensional numerical analysis, when numerical analysis for curved channel is conducted.

• 한국지반공학회지:지반
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• 제12권6호
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• pp.127-138
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• 1996

배수재가 설치된 연약지반의 현장거동은 3차원적인 특성을 나타낸다. 그러므로 보다 효율적인 2차원 평면변형률 수치모델을 이용하여 적절하게 해석하기 위해서는 현장지반의 3차원적인 흐름특성을 평면변형률 모델의 층류흐름으로 전환할 필요성이 있다. 본 논문에서는 배수재가 설치된 연약지반의 3차원적인 거동특성을 고려하기 위하여 등가의 효과적인 모델방법이 유한요소법에 적용되었다. 2차원 등가모델은 등가투수계수와 배수재의 강성토를 고려한 등가폭을 가진다. 제안된 등가모델을 검증하기 위하여 ABAQUS 프로그램을 이용한 3차원 압밀해석을 수행하였으며, 3차원 해석결과와 2차원 해석결과를 비교하였다. 제안된 등가모델을 적용한 2차원 평면변형률 수치해석방법은 현장지반의 3차원적인 거동특성을 비교적 정확히 예측할 수 있다.

• 한국자동차공학회논문집
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• 제3권3호
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• pp.97-108
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• 1995

A 3-dimensional double track vehicle model, that has 12-degress-of-freedom, was proposed to analyze handling and riding behaviours of an automotive car. Nonlinear characteristics of the suspension and steering systems of the vehicle model were considered in its equations of motion, which were solved by using the 4th-order Runge-Kutta integration method. Computer simulations for lane change, steady-state handling, and running-over-bump manoeuvres were made and verified by vehicle tests on proving ground. The computed results of the proposed model showed better agreement with test results than those of the conventional 2-dimensional single track model did. Especially they showed good accuracy near the characteristic speed and in high lateral accelerated manoeuvres.