• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.865-875
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• 1988

A two-dimensional stepped wall jet was numerically investigated by applying three different models : One is the standard k-.epsilon. and the other is the modified k-.epsilon. model which takes account of the streamline curvature effect by modifying the Reynolds shear stress and a source term in the dissipation equation, and a third is curvature dependent third-order correlation model. In order to test the influences of the numerical result, both the upwind scheme and the skew-upwind scheme were sued for the computations. By comparing the numerical results with available experiments, it was found that the modified k-.epsilon. model gives best overall prediction accuracy only when the numerical diffusion is eliminated by using the skew-upwind scheme. The numerical scheme was found to have more pronounced effect on the accuracy of the turbulence computation than the turbulence models.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.135-140
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• 2006

Numerical computations are made to predict wave loads on a vertical cylinder in an extreme wave. To generate the extreme wave, a frequency-focused unidirectional wave is adopted in three-dimensional numerical wave tank. The mathematical formulation is wide in the scope of the potential theory with fully nonlinear free surface conditions. As a numerical method, finite element method based on variational principle is applied. Comparisons between the present numerical results and the previous computation data. show a good agreement.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.85.1-85.1
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.69-70
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• 2012

• Journal of the Korean Mathematical Society
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• v.31 no.4
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• pp.633-643
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• 1994

Let us consider the initial-value problem of dimension m: $$ \frac{d\tau}{d}y(\tau) = f(\tau, Y(\tau)), y(0) = y_0, \tau \geq 0, (1.1) $$ Where $ = (f_1, f_2, \cdots, f_m) and y = (y_1, y_2, \cdots, y_m)$.

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.389-390
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• 2006

• 한국전산유체공학회:학술대회논문집
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• 2006.05a
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• pp.209-210
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• 2006

• Journal of Applied and Pure Mathematics
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• v.5 no.5_6
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• pp.291-301
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• 2023

In this paper, we investigate the zeros of the fully modified q-poly-tangent polynomials of the first type.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.819-827
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• 2007

A numerical algorithm for estimating precise backscattering coefficients of rice fields is proposed and its accuracy is verified in this paper. After a bunch of rice plants above water surface is modeled with a bunch of randomly oriented lossy dielectric bodies above an impedance surface and the equivalent volume currents of the lossy dielectrics are computed using the moment method. Then, the scattered fields of a rice field with many bunches are computed with a Monte Carlo method, and consequently the backscattering coefficient of the rice field is computed for various incidence angles and polarizations. Finally, the backscattering coefficient of a rice field is measured at 1.85 GHz using an R-band scatterometer system, and these experimental data are used to verify the numerical algorithm proposed in this paper. It is found that the numerical computation results agree well with the measurement data.

• Structural Engineering and Mechanics
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• v.87 no.5
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• pp.461-473
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• 2023

This study aims to solve for nonlinear cylindrical shell systems with a semi-analytical and numerical approach implementing the P-T method. The procedures and conditions for such a study are presented in practically solving and analyzing the cylindrical shell systems. An analytical model for a nonlinear thick cylindrical shell (TCS) is established on the basis of the stress function and Reddy's higher-order shear deformation theory (HSDT). According to Reddy's HSDT, Hooke's law in three dimensions, and the von-Kármán equation, the stress-strain relations are developed for the thick cylindrical shell systems, and the three coupled nonlinear governing equations are thus established and discretized as per the Galerkin method, for implementing the P-T method. The solution generated with the approach is continuous everywhere in the entire time domain considered. The approach proposed can also be used to numerically solve and analyze the nonlinear shell systems. The procedures and recurrence relations for numerical solutions of shell systems are presented. To demonstrate the application of the approach in numerically solving for nonlinear cylindrical shell systems, a specific nonlinear cylindrical shell system subjected to an external excitation is solved numerically. In numerically solving for the system, the present approach shows higher efficiency, accuracy, and reliability in comparison with that of the Runge-Kutta method. The approach with the P-T method presented is practically sound especially when continuous and high-quality numerical solutions for the shell systems are considered.