• 한국전산유체공학회지
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• 제7권2호
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• pp.25-32
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• 2002

The velocity and temperature profiles in the cabin of the automobile affect greatly the comfortableness of passengers. In this paper, the three dimensional flow and temperature analysis in the cabin of real automobile have been peformed. The three dimensional Navier-Stokes equation solver was validated by comparing with the other numerical data of a 1/5 scale model. The temperature field of cavity was also analyzed for the validation of energy equation solver. After the code validation, the numerical analysis of real field of flow and temperature of an automobile was peformed and the present result provides the insight of flow and temperature field of the inside of cabin.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.174-180
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• 1998

Numerical study of three-dimensional turbulent flow in a forward curved centrifugal fan is presented. Standard $k-{\varepsilon}$ turbulence model and non-orthogonal curvilinear coordinates are used to consider the turbulent flow field and complex geometry. Finite Volume approach is adopted for discretization scheme and structured grid system is used to help convergence. Multiblock grid system is used for flow field and divided into five domains that are inlet, outlet, impeller, tip clearance and scroll. It is assumed that the flow field is steady state and incompressible. This numerical work is performed with commercial CFD-ACE code developed by CFD Research Corporation, and the results are compared wi th the experimental data

• 한국방재학회 논문집
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• 제5권3호
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• pp.73-82
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• 2005

본 연구에서는 도시하천의 통수능 확보를 위한 방안이 제시되었다 하천 좌우안을 따라 형성된 도로 하부를 통수능으로 사용하기 위해, 2차원 분석에 의해 통수단면의 제원에 따른 흐름특성을 검토하여 적합한 통수단면의 제원을 제시하였다. 주수로와 추가되는 통수단면간의 흐름 분석을 위해 2차원 수치 모형인 SMS를 이용하였고, SMS의 모형의 매개변수를 검정하기 위해 1차원 수치 모형인 HEC-RAS의 결과를 이용하였다. 제시된 통수능 확보 방안은 청계천 복원사업에 적용하였다. 50, 80, 200년 빈도 홍수에 대한 통수단면의 내수배제 능력을 검토하였으며, 적합한 통수단면의 제원을 제시하였다.

• 한국추진공학회지
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• 제4권3호
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• pp.45-54
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• 2000

Ignition transient is a. very rapid process lasting only in the order of 100 milliseconds and therefore it is difficult to measure all relevant ballistic properties. Numerical simulation is thus useful to quantify some of these hard to measure flow and ballistic properties. One-dimensional model was employed to study the effects of aging using simplified aging scenarios for both N-H sustainer and booster motors. Also the effects of newly designed igniter on the ignition of N-H sustainer was simulated. Radiation effects could be significant in terms of energy flux increase to the propellant surface and the energy exchange between the combustion gas itself. One dimension implementation of radiation showed significant effects for rear-mounted igniter. Implementation of radiation effects into 2-D axi-symmetric numerical model was completed and its effects on the N-H sustainer were examined. To have a reliable prediction of computer model on ignition transient, accurate chemical property data on the propellant and igniter gas are required. It was found that such property data on aged N-H motors are not available. Chemical aging model can be used to predict to some degree of accuracy effects of aging on chemical and mechanical properties. Such a model was developed, albeit 2-dimensional, to study migration of moisture through a representative solid rocket motor configuration.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.457-460
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• 2006

This study is to investigate the variation characteristics of run-up height over sandy beach due to the plane distribution of submerged breakwaters. In this study, Three-Dimensional numerical model with Large Eddy Simulation, which is able to simulate directly WAve Structure Seabed interaction (hereafter, LES-WASS-3D) has been newly developed. A comparison between the numerical model and existing experimental results was made to verify accuracy of newly proposed LES-WASS-3D model, and showed fairly nice agreement. In addition, based on the LES-WASS-3D model, the variation characteristics of run-up height over sandy beach are discussed with relation to the offshore distance and opening width of submerged breakwaters.

• International Journal of Naval Architecture and Ocean Engineering
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• 제3권3호
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• pp.216-224
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• 2011

In This study develops a quasi-three dimensional numerical model of wave driven coastal currents with accounting the effects of the wave-current interaction and the surface rollers. In the wave model, the current effects on wave breaking and energy dissipation are taken into account as well as the wave diffraction effect. The surface roller associated with wave breaking was modeled based on a modification of the equations by Dally and Brown (1995) and Larson and Kraus (2002). Furthermore, the quasi-three dimensional model, which based on Navier-Stokes equations, was modified in association with the surface roller effect, and solved using frictional step method. The model was validated by data sets obtained during experiments on the Large Scale Sediment Transport Facility (LSTF) basin and the Hazaki Oceanographical Research Station (HORS). Then, a model test against detached breakwater was carried out to investigate the performance of the model around coastal structures. Finally, the model was applied to Akasaki port to verify the hydrodynamics around coastal structures. Good agreements between computations and measurements were obtained with regard to the cross-shore variation in waves and currents in nearshore and surf zone.

• 한국도로학회논문집
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• 제10권1호
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• pp.1-9
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• 2008

도로기하설계의 기준이 되는 요소에는 시거(視距), 차량의 안정성, 운전자의 안락감, 배수, 경관 등이 있으며, 이 중 선형 결정에 있어서 가장 결정적인 요소는 시거이다. 도로와 그 위를 주행하는 운전자의 관찰 행위는 분명히 입체적인 특성을 가지고 있다. 그러나, 현행의 도로설계는 과정상 여러 가지 제약조건으로 인해 평면과 종단을 분리하여 2차원적으로 시거를 분석하여 설계시 적용하여 왔다. 입체시거의 계산이 까다롭고 2차원적인 시거가 실제의 입체시거와 크게 차이가 나지 않는 것도 그 원인에 포함된다. 하지만 최근의 도로안전에 관한 연구에서 도로일관성이 대두되었고, 이러한 일관성 평가를 위해서는 안전요소들의 안전여유(safety of margin)를 계산할 수 있어야 한다. 따라서 시거에 관한 정확한 안전여유를 계산하기 위해서는 정확한 입체시거의 적용이 필요하다고 할 수 있다. 본 연구는 임의의 평면선형과 종단선형의 합성으로 이루어진 도로선형에서 입체시 거를 계산할 수 있는 모형을 유도하는데 초점을 두었다. 제시되는 모델을 이용하여 도로선형을 가정한 후 시거분석을 실시해 보았으며 2차원적 시거와의 단순비교를 통하여 두 경우의 시거에 차이가 있음을 확인하였다. 제안된 모델은 3차원 도로선형에 대한 설계기준을 정량화 하거나 입체시거 분석이 요구되는 도로안전의 연구에 기여할 수 있을 것으로 기대된다.

• Advanced Composite Materials
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• 제18권1호
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• pp.1-20
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• 2009

This paper describes the results of experiments and numerical simulation studies on the impact and indentation damage created by low-velocity impact subjected onto honeycomb sandwich panels for application to the BIMODAL tram. The test panels were subjected to low-velocity impact loading using an instrumented testing machine at six energy levels. Contact force histories as a function of time were evaluated and compared. The extent of the damage and depth of the permanent indentation was measured quantitatively using a 3-dimensional scanner. An explicit finite element analysis based on LS-DYNA3D was focused on the introduction of a material damage model and numerical simulation of low-velocity impact responses on honeycomb sandwich panels. Extensive material testing was conducted to determine the input parameters for the metallic and composite face-sheet materials and the effective equivalent damage model for the orthotropic honeycomb core material. Good agreement was obtained between numerical and experimental results; in particular, the numerical simulation was able to predict impact damage area and the depth of indentation of honeycomb sandwich composite panels created by the impact loading.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.107-108
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• 2008

The temperature rise of GIS (Gas Insulated Switchgear) busbar system is a vital factor that affects its performance. In this paper, a two-dimensional model is presented by commercial code CFX11 for the evaluation of natural convection in the busbar system. In the model, SF6 (Sulfur Hexafluoride) is used to insulate the high voltage device and improves the heat transfer rate. The power losses of a busbar calculated by the magnetic field analysis are used as the input data to predict the temperature rise by the nature convection analysis. The heat-transfer coefficients on the boundaries are analytically calculated by applying the Nusselt number considering material property and model geometry for the natural convection. The temperatures of the tank and conductors from CFX simulation and the experiment were compared. The results show a good agreement. In the future, we will calculate the 3-D model and try to reduce the temperature by adjusting some dimensional parameters.

• 한국정밀공학회지
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• 제13권5호
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• pp.115-121
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• 1996

Recently, the Z-Map model has been used widely to represent the three dimensional geometric shape and to achieve the cross-section and point evaluation of the shape. In this paper, the CNC cutting planning and simulation modules for product with three dimensional geometric shape are realized based on the Z-Map model. The realized system has the various capabilities related to the automatic generation of tool path for the rough and finish cutting processes, the automatic elimination of overcut, the automatic generation of CNC program for a machining center and the cutting simulation. Especially, the overcut-free tool path is obtained by using the CL Z-Map models which are composed of the offset surfaces of the geometric shape of product.