• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1716-1720
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• 2000

To develop the code of predicting flow-field and aeroacoustic noise by a electrical cable, a combined CFD-acoustic analogy approach is selected. The two-dimensional, unsteady, incompressible Reynolds-Averaged Navier-Stokes solver with a ${\kappa}{\omega}$, ${\kappa}{\omega}$ SST turbulence modeling is used to calculate the near-field around electrical cable. Near-field results are then coupled with two-dimensional Curle's integral formulation based upon Lighthill's acoustic analogy with an assumption of acoustic compactness. To validate this code, numerical results are compared with experimental data for a circular cylinder. The simulation shows an overprediction on acoustic amplitudes, but overally speaking, the spectrum pattern of sound pressure agrees well with experiment in an acceptable amount of error. In addition, various cross sections of a cable were selected and compared with each other in terms of drag and radiated noise.

• Water Engineering Research
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• 제4권1호
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• pp.45-58
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• 2003

Two-dimensional depth-averaged advection-dispersion equation was simulated using FEM. In the straight rectangular channel, the advection-dispersion processes are simulated so that these results can be compared with analyti-cal solutions for the transverse line injection and the point injection. In the straight domain the standard Galerkin method with the linear basis function is found to be inadequate to the advection-dispersion analysis compared to the upwind finite element scheme. The experimental data in the S-curved channel were compared with the result by the numerical model using SUPG(Streamline upwind Petrov-Galerkin) method.

• Computers and Concrete
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• 제33권6호
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• pp.671-688
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• 2024

The modeling efficiency of concrete meso-models close to real concrete is one of the important issues that limit the accuracy of mechanical simulation. In order to improve the modeling efficiency and the closeness of the numerical aggregate shape to the real aggregate, this paper proposes a method for generating a two-dimensional concrete meso-model based on pixel matrix and skeleton theory. First, initial concrete model (a container for placing aggregate) is generated using pixel matrix. Then, the skeleton curve of the residual space that is the model after excluding the existing aggregate is obtained using a thinning algorithm. Finally, the final model is obtained by placing the aggregate according to the curve branching points. Compared with the traditional Monte Carlo placement method, the proposed method greatly reduces the number of overlaps between aggregates by up to 95%, and the placement efficiency does not significantly decrease with increasing aggregate content. The model developed is close to the actual concrete experiments in terms of aggregate gradation, aspect ratio, asymmetry, concavity and convexity, and old-new mortar ratio, cracking form, and stress-strain curve. In addition, the cracking loss process of concrete under uniaxial compression was explained at the mesoscale.

• Journal of applied mathematics & informatics
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• 제26권1_2호
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• pp.365-374
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• 2008

We study a mathematical modeling for development of film negative and concentrate the bulk reaction problem. We prove nonnegativeness of developer, coupler and dye function in two dimensional case. Also we prove stability of our numerical scheme. Finally, we discuss numerical example which have specified constants.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.548-551
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• 1989

Two dimensional numerical analysis program of power VDMOSFET structure has been developed. Modeling and analysis on the electrical characteristics of the device are presented These are available for the device structure optimization and physical understanding of the behavior of the device

• JSTS:Journal of Semiconductor Technology and Science
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• 제7권4호
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• pp.287-298
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• 2007

A two-dimensional treatment of the potential distribution under the depletion approximation is presented for poly-crystalline silicon thin film transistors. Green's function approach is adopted to solve the two-dimensional Poisson's equation. The solution for the potential distribution is derived using Neumann's boundary condition at the silicon-silicon di-oxide interface. The developed model gives insight into device behavior due to the effects of traps and grain-boundaries. Also short-channel effects and drain induced barrier lowering effects are incorporated in the model. The potential distribution and electric field variation with various device parameters is shown. An analysis of threshold voltage is also presented. The results obtained show good agreement with simulated results and numerical modeling based on the finite difference method, thus demonstrating the validity of our model.

• 지질공학
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• 제6권3호
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• pp.119-130
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• 1996

경계요소법을 이용한 2차원 전기비저항 모델링을 위한 이론적 전개와 수치계산 기술이 주어졌다. 균질 지하모델과 층상구조 지하모델에 대한 점전류전원에 대한 전위분포가 경계요소법을 이요하여 계산되으며, 그 결과는 동일 모델에 대해서 수행된 유한차분법, 유한요소법의 수치 결과와 비교 연구되었다. 경계요소법을 사용한 2차원 전기모델링은 저장용량, 계산속도 및 정확도에서 유한요소법이나 유한차분법에 비해 효율적임이 입증되었다.

• 터널과지하공간
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• 제7권4호
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• pp.334-340
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• 1997

Alpha center theory which was first proposed by Stefanescu has been proved to be effective for the detection of the location of the conductive orebody. A numerical forward modeling was conducted to verify the effectiveness of this method. Field works were carried out along the three profiles in two different areas for the purpose of finding fractured zone which might be accompanied with the presence of the groundwater. And the results were modeled by alpha center method, which was later testified by wellproven 2-dimensional finite difference inversion scheme. Field data could be successfully modeled with this alpha center algorithm, especially for the smooth-varying resistivity models. For the abrupt change of the resistivity values, the alpha center coefficients have a tendency to be negative to simulate the steep resistivity gradients. This method is quite simple and easy for the future applications. The numerical calculation can be performed very quickly with the personal computers.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.22-27
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• 2006

This paper describes the development of the stream-tube based dispersion model for modeling contaminant transport in open channels. The operator-splitting technique is employed to separate the 2D contaminant transport equation into the pure advection and pure dispersion equations. Then the total variation diminishing (TVD) schemes are combined with the second-order Lax-Wendroff and third-order QUICKEST explicit finite difference schemes respectively to solve the pure advection equation in order to prevent the occurrence of numerical oscillations. Due to various limiters owning different features, the numerical tests for 1D pure advection and 2D dispersion are conducted to evaluate the performance of different TVD schemes firstly, then the TVD schemes are applied to experimental data for simulating the 2D mixing in a straight trapezoidal channel to test the model capability. Both the numerical tests and model application show that the TVD schemes are very competent for solving the advection-dominated transport problems.

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1519-1528
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• 2018

The objective of the present study is the development of a comprehensive air chemical kinetic model that includes 11 species and 54 chemical reactions for the numerical investigation of air nonequilibrium inductively coupled plasmas. The two-dimensional, compressible Navier-Stokes equations coupled with the electromagnetic-field equations were employed to describe the fundamental characteristics of an inductive plasma. Dunn-Kangs 32 chemical-reaction model of air was reconstructed and used as a comparative model. The effects of the different chemical kinetic models on the flow field were analyzed and discussed at identical/different working pressures. The results theoretically indicate that no matter the working pressure is low or high, the use of the 54 chemical kinetic model presented in this study is a better choice for the numerical simulation of a nonequilibrium air ICP.