• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.481-489
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• 2006

Two dimensional diffusion model test was conducted to investigate the sedimentation properties and consolidation process of reclaimed ground using dredging coarse soil which is composed of passing amount 20 percentage and 45 percentage of #200 sieve size respectively. The passing amount of #200 sieve size affected on sedimentation properties. The coarse soil which is passing amount of 20 percent showed that the sedimentation structure was layered type and passing amount of 45 percentage was wall-partition type according diffusion distance. Furthermore, the water content of surface and section, and distribution of fine soil were changed according to diffusion distance. and the change amount of pore water pressure and strength property when soil is diffused, segregated and accumulated can be applied efficiently in design of dredging and reclamation.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.414-419
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• 2011

Missile am fighter aircraft have been challenged by low restoring nose-down pitching moment at high angle of attach. The consequence of weak nose-down pitching moment can be resulting in a deep stall condition. Especially, the pressure oscillation has a huge effect on noise generation, structure damage, aerodynamic performance and safety, because the flow has strong unsteadiness at high angle of attack. In this paper, the unsteady aerodynamics coefficients were analyzed at high angle of attack up to 60 degrees around two dimensional NACA0012 airfoil. The two dimensional unsteady compressible Navier-Stokes equation with a LES turbulent model was calculated by OHOC (Optimized High-Order Compact) scheme. The flow conditions are Mach number of 0.3 and Reynolds number of $10^5$. The lift, drag, pressure distribution, etc. are analyzed according to the angle of attack. The results at a low angle of attack are compared with other results before a stall condition. From a certain high angle of attack, the strong vortex formed by the leading edge are flowing downstream as like Karman vortex around a circular cylinder. Unsteady velocity field, periodic vortex shedding, the unsteady pressure distribution on the airfoil surface, and the acoustic fields are analyzed. The effects of these unsteady characteristics in the aerodynamic coefficients are analyzed.

• Korean Journal of Hydrosciences
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• v.3
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• pp.61-79
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• 1992

In oder to predict the dispersion of a thermal discharge with strong turbulent and buoyant effects, the development of a numerical model using turbulence model and its application are significantly increased. In this study, a three-dimensional steady-state model for the surface discharge heated water into quiescent water body is developed. For the model closure of turbulent terms the four-equation turbulence model is used. For economic mumerical simulation, the elliptic governing equations are transformed to the partially parabolic equations. In general, the simulated results by the present model agree well with the experimental results by Pande and Rajratnam (1977). The model characteristics are presented in comparison with the predicted results from the two-eqauation turbulence model by McGuirk and Rodi (1979).

• Nuclear Engineering and Technology
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• v.32 no.3
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• pp.235-243
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• 2000

A one-dimensional neutronics formulation is established within the framework of the nonlinear analytic nodal method such that it can result in consistent one-dimensional models that produce the same axial information as their corresponding reference three-dimension81 models. Consistency is achieved by conserving axial interface currents as well as the planar reaction rates of the three-dimensional case. For current conservation, flux discontinuity is introduced in the solution of the two-node problem. The degree of discontinuity, named the current conservation factor, is determined such that the surface averaged axial current of the reference three-dimensional case can be retrieved from the two-node calculation involving the radially collapsed group constants and the discontinuity factor. The current conservation factors are derived from the analytic nodal method and various core configurations are analyzed to show that the errors in K-eff and power distributions can be reduced by a order of magnitude by the use of the current conservation factor with no significant computational overhead.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.91-98
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• 1993

A two-dimensional turbulence model for the surface discharge of heated water into cross-flow field has been developed. The depth-averaged continuity, momentum and temperature equations, are solved by an efficient finite-difference procedure known as SIMPLE. Turbulent stresses and heat fluxes are determined from a depth-averaged version of the $textsc{k}$-$\varepsilon$ equation. Results of test run clearly demonstrate its effectiveness in handling strong turbulent phenomena in very shallow near-field region.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.15-18
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• 2004

A numerical method for simulating two-phase flows including surface force is presented. The method is based on fractional step method of finite volume formulation and the interface is tracked with PLIC VOF method. In the CSF model, as color function, f, representing the location of interface varies steeply in the interface region, we need to use smoothed function f to get accurate unit normal and the curvature. Peskin kernel is used to get smoothed function f. A spherical drop in static equilibrium and three-dimensional merging of gas bubble are tested, resulting in the validation of this method

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.399-402
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• 1999

In this paper, a new method for calculating capacitance in arbitrarily shape structure is Presented. This new approach based on divergence theorem of Gauss\`s law is acheive by Surface-Contacted Element(SCE) for Gaussian surface. To evaluate accurate capacitance value in nonuniform electric field. in two dimensional analysis the interpolation using the elements which contact one nod (PE: Point-Element) or two nod (FE: Face-Element) is employed. Because the elements contacted with surface are very small compared with total elements in analytic model, SCE method has shorter computing time to calculate capacitance. This proposed method is verified by comparing the simulated results with value obtained by analytic method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.1
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• pp.6-14
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• 2012

For integrated complementary metal oxide semiconductor (CMOS) circuits, the lateral spread for two-dimensional (2-D) impurity distributions are very important for the analyzing the devices. The measured two-dimensional SEM data obtained using the chemical etching-method matched very well with the results of the Gauss model for boron implanted samples. But the profiles in boron implanted silicon were deviated from the Gauss model. The profiles in boron implanted silicon were shown a little bit steep profile in the deep region due to backscattering effect on the near surface from the bombardments of light boron ions. From the simulated 3-D data obtained using an analytical model, the 1-D and 2-D data were compared with the experimental data and could be verified the justification from the experimental data. The data of 3-D model were also shown good agreements with the experimental and the simulated data. It can be used in the 3-D chip design and the analysis of microelectro-mecanical system (MEMS) and special devices.

• Water for future
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• v.16 no.4
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• pp.221-236
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• 1983

In semi-enclosed shallow sea areas typified by the Yellow sea and the East China Sea, currents and sea surface variations are predominantly tidal. During the recent years two-dimensional numerical hydrodynamic model of the Yellow Sea and the East China Sea has been developed, based on the vertically-integrated equations of motion and continuity, capable of reproducing amplitudes and phases of the principal components of tides to satisfiable accuracy. As a subsequent development a three-dimensional hydrodynamical nymerical model covering the Yellow Sea and the East China Sea has been formulated to investigate the vertical distribution of horizontal tidal current and the response of the continented to investigate the vertical distribution of horizontal tidal current and the response of the continental shelf sea to steady uniform wind stress field imposed over the surface. Features of the M2 tidal current and the wind-induced three-dimensional current structure determined from the computation have been examined and discussed.

• New Physics: Sae Mulli
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• v.68 no.11
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• pp.1275-1280
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• 2018

We demonstrated transmission direct phase-measuring deflectometry (DPMD) with a specular phase object having discontinuous surfaces by using two displays and a two-dimensional array detector for display and by recording the distorted fringe patterns. Three-dimensional (3D) information was obtained by calculating the height map directly from the phase information. We developed a mathematical model of the phase-height relationship in transmission DPMD. Unlike normal transmission deflectometry, this method supports height measurement directly from the phase. Compared with other 3D measurement techniques such as interferometry, this method has the advantages of being inexpensive and easy to implement.