• 한국지구물리탐사학회:학술대회논문집
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• 2003.11a
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• pp.661-668
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• 2003

This paper presents Lattice-Boltzmann simulation techniques for single-phase and two-phase fluid flow in porous media. Numerical experiments were performed in a digital rock sample from X-ray microtomography. Computed results showed very good agreement with laboratory measurements of permeability and relative permeability. Two applications using these simulation techniques show the potential of the Lattice-Boltzmann flow simulation to solve many difficult problems coupled with fluid flow in porous media.

• Journal of information and communication convergence engineering
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• v.5 no.3
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• pp.281-284
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• 2007

We have analyzed the short pulse generation using heterodyne techniques. The numerical model for semiconductor lasers under the heterodyne technique is based on the Lang's equation and has been extended in order to take into account the simultaneous injection of the multiple sidebands of the current-modulated laser. The unselected sidebands will affect the optical and RF-spectral characteristics even when the semiconductor laser is locked to the target sidebands.

• 한국전산유체공학회:학술대회논문집
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• 2002.10a
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• pp.84-87
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• 2002

When computing the flow around complex three dimensional configurations, the generation of grid is the sunt time consuming part of any calculation. The object of this study is to develop the grid duster techniques capable of resolving complex flows with shock waves, expansion waves, shear layers, and cursive shapes, The Dot insert method of Non-Uniform Rational B-Splines is described as a id control method.

• 한국전산유체공학회:학술대회논문집
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• 1995.04a
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• pp.44-68
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• 1995

In the present paper, visualization techniques in fluid dynamic experiments such as Schlieren photograph are numerically simulated so that the same output as the experimental flow visualization can be obtained from the computed results for the fair comparison. Numerical methods to simulate optical visualizations, that are Schlieren photograph, shadowgraph and interferogram, are considered. Some examples of pictures obtained by the present methods show the importance of the simulations of visualization techniques for the correct comparisons of the computations and experiments.

• Proceedings of the Korea Society for Simulation Conference
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• 1994.10a
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• pp.1-2
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• 1994

With the prevalence of computers in modern organizations, simulation is receiving more atention as an effectvie decision -making tool. Simualtion is a computer-based numerical technique which uses mathmatical and logical models to approximate the behaviror of a real-world system. However, iptimization of synamic stochastic systems often defy analytical and algorithmic soluions. Although a simulation approach is often free fo the liminting assumption s of mathematical modeling, cost and time consiceration s make simulation the henayst's last resort. Therefore, whenever possible, analytical and algorithmica solutions are favored over simulation. This paper discussed the issues and procedrues for using simulation as a tool for optimization of stochastic complex systems that are dmodeled by computer simulation . Its emphasis is mostly on issues that are speicific to simulation optimization instead of consentrating on the general optimizationand mathematical programming techniques . A simulation optimization problem is an optimization problem where the objective function. constraints, or both are response that can only be evauated by computer simulation. As such, these functions are only implicit functions of decision parameters of the system, and often stochastic in nature as well. Most of optimization techniqes can be classified as single or multiple-resoneses techniques . The optimization of single response functins has been researched extensively and consists of many techniques. In the single response category, these strategies are gradient based search techniques, stochastic approximate techniques, response surface techniques, and heuristic search techniques. In the multiple response categroy, there are basically five distinct strategies for treating the responses and finding the optimum solution. These strategies are graphica techniqes, direct search techniques, constrained optimization techniques, unconstrained optimization techniques, and goal programming techniques. The choice of theprocedreu to employ in simulation optimization depends on the analyst and the problem to be solved. For many practival and industrial optimization problems where some or all of the system components are stochastic, the objective functions cannot be represented analytically. Therefore, modeling by computersimulation is one of the most effective means of studying such complex systems. In this paper, after discussion of simulation optmization techniques, the applications of above techniques will be presented in the modeling process of many flexible manufacturing systems.

• Journal of applied mathematics & informatics
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• v.10 no.1_2
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• pp.175-191
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• 2002

The equations of a polar fluid of hydromagnetic fluctuating through a porous medium axe cast into matrix form using the state space and Laplace transform techniques the resulting formulation is applied to a variety of problems. The solution to a problem of an electrically conducting polar fluid in the presence of a transverse magnetic field and to a problem for the flow between two parallel fixed plates is obtained. The inversion of the Laplace transforms is carried out using a numerical approach. Numerical results for the velocity, angular velocity distribution and the induced magnetic field are given and illustrated graphically for each problems.

• Journal of applied mathematics & informatics
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• v.8 no.2
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• pp.539-550
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• 2001

In the present investigation, we study the influence of a transverse magnetic field through a porous medium. Laplace transform techniques are used to derive the solution in the Laplace transform domain. The inversion process is carried out using a numerical method based on Fourier series expansions. Numerical computations for the temperature, the microrotation and the velocity distributions as well as for the induced magnetic and electric fields and carried out and represented graphically.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.591-593
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• 2007

최근 에너지효율이 높은 고출력 HF 레이저에 대한 관심이 다시 높아지고 있다. 레이저점화방식의 최적설계와 출력특성의 향상을 위해 정확한 이론해석 모델이 필요하다. 따라서 본 연구에서는 최신의 반응정수를 적용한 HF 화학레이저 모델을 구축하였다.

• Journal of Ocean Engineering and Technology
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• v.14 no.3
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• pp.35-40
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• 2000

SMAC method is, one of the numerical simulation techniques, modified from the original MAC for the time-dependent variation of fluid flows. The Navier-Stokes equation for incompressible time-dependent viscous flow is applied and, also marker particles which move with the fluid are used. Two-dimensional numerical computations of fluid flow are carried out in a virtual water tank. This paper has shown very well the movements of marker particles using SMAC method.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.205-210
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• 2000

An optimum design algorithm of PSC box girder bridges using design sensitivity analysis is proposed in this paper. For the efficiency of the proposed algorithm, approximated reanalysis techniques using design sensitivity analysis are introduced. And also to save the numerical efforts, an efficient reanalysis technique through approximated structural responses is proposed. A design sensitivity analysis of structural response is executed by automatic differentiation(AD). The efficiency and robustness of the proposed algorithm, compared with conventional algorithm, is successfully demonstrated in the numerical example.