• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.1
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• pp.47-56
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• 1999

최근 요소망의 구성없이 공학적인 문제의 해석이 가능한 무요소법이 많은 학자들에 의하여 제안되고 이에 관한 집중적인 연구가 이루어지고 있다. 본 연구에서는 갤러킨 정식화에 의한 무요소법을 고체역학적인 문제에 적용하여 이의 특성을 규명하고자 하였다. 특히 일반적으로 사용되고 있는 몇가지 가중 함수를 선정하여 이들이 해석결과에 미치는 특성과 절점 배치방법 및 가중 함수의 영향 영역 변화에 따른 해의 정확도 등을 서로 비교하고 검토하였다. 연구결과로 가중 함수의 형태와 영향 영역의 크기, 기정 함수의 차수와 절점 배치방법 등은 서로 상관관계를 갖고 해의 정확도에 크게 영향을 미침을 확인할 수 있었고 이의 적절한 선정은 무요소해석의 중요한 요건임을 알 수 있었다.

• Journal of Navigation and Port Research
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• v.31 no.9
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• pp.793-799
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• 2007

The effect of seasonal wind on the tidal circulation in Jeju harbor was examined by using a numerical shallow water model. A finite element for analyzing shallow water flow is presented. The Galerkin method is employed for spatial discretization. Two step explicit finite element scheme is used to discretize the time function, which has advantage in problems treating large numbers of elements and unsteady state. The numerical simulation is compared with three cases; Case 1 does not consider the effect of wind, Case 2 and Case 3 consider the effect of summer and winter seasonal wind, respectively. According to result considering effect of seasonal wind, velocity of current vector shows slightly stronger than that of case 1 in the flow field. It can be concluded that the present method is a useful and effective tool in tidal current analysis.

• Water for future
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• v.14 no.2
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• pp.53-62
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• 1981

In the Hydraulic Structure, Such as dam body or levee of river that is constructed with soil, We analyzed a top line of free ground water table. This study is based on the logical reason that the pressure on the free surface is atmospheric and the seepage line is a stream line. In order to research for the unknown seepage line. We analyzed seepage water of steady flow through parous media by Finite Element method based on Galerkin Principle, and compared the comluted value with experimental value. The results show that the computed value was nearly equal to the experimental value. Finally, it noticed that finite Element method was more practical than Experimental Method for Seepage line analysis.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.157-162
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• 1996

A novel nodal method is developed for the two-dimensional multi-group diffusion equations based on the Spectral-Galerkin approach. In this study, the nodal diffusion equations with Robin boundary condition are reformulated in a weak (variational) form, which is then approximated spatially by choosing appropriate basis functions. For the nodal coupling relations between the neighbouring nodes, the continuity conditions of partial currents are utilized. The resulting discrete systems with sparse structured matrices are solved by the Preconditioned Conjugate Gradient Method (PCG) and sweeping technique. The method is validated on two test problems.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.9
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• pp.797-805
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• 2013

In this paper vibration and stability analysis of laminated composite shells based on the first order shear deformation theory(FSDT) for two different boundary conditions(clamped-clamped, simply supported) are performed. Structural model of cross-ply symmetric laminated composite cylindrical shells subjected to a combination of magnetic and thermal fields is developed via Hamilton's variational principle. These coupled equations of motion are based on the electromagnetic equations(Faraday, Ampere, Ohm, and Lorenz equations)and thermal equations which are involved in constitutive equations. Extended Galerkin method is adopted to obtain the discretized equations of motion. Variations of dynamic characteristics of composite shells with applied magnetic field, temperature gradient, laminate thickness-ratio and radius ratio for two boundary conditions are investigated and pertinent conclusions are derived.

• Journal of Korea Water Resources Association
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• v.34 no.2
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• pp.107-118
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• 2001

This study was to develop a tow-dimensional model system for the hydrodynamic analysis and to apply the system on the downstream of Han River. it is performed to design a GIS-based hydrodynamic system for the scientific shallow water profile analysis, and to compare hydrodraulic modeling is the Petrov-Galerkin's finite element method for flow prediction model. This study was to construct a GIS-based river flow system, and it is useful for supporting user's decision making for the on-line status through various analysis. We expect that the results from this study can be used as one of the guidelines for river analysis and management system in order rivers, reservoirs, and estuaries.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.569-574
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• 2020

Though the discontinuous Galerkin (DG) method has been developed and applied to shallow water equations mainly in explicit schemes, they have been criticized for the limitation in treatment of bottom friction terms and severe CFL conditions. In this study, an implicit scheme is devised and applied to some representative benchmark problems. The linear triangular elements were employed and the Roe numerical fluxes were adopted for convective fluxes. To preserve TVD property, the slope limiter was employed. As the case studies, the model is applied to the flow around the cylinders and the dam-break flow. Then, the results are compared with the experimental and numerical data of previous studies and good agreements were observed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4158-4163
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• 2015

In this paper, the solutions of TE(transverse electric) scattering problems by a condutive strip grating over a dielectric layer are analyzed by using the FGMM(fourier galerkin moment method) and PMM(point matching method) known as a numerical method of electromagnetic fileld. The scattered electromagnetic fields are expanded in a series of floguet mode functions, the boundary conditions are applied to obtain the unknown field coefficients, and the conductive boundary condition is used for the relationship between the tangential electric field and the induced surface current density on the strip. The numerical results for the reflected and transmitted power of zeroth mode analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of dielectric layer, and incident angles. Generally, according to the relative permittivity of dielectric layer increased, also the normalized reflected power of zeroth mode increased. To examine the accruacy of this paper, the numerical results of FGMM shown in good agreement compared to those of PMM.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.3
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• pp.159-166
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• 2003

In this study, we develop a finite element model to directly solve the Laplace equation while keeping the same computational efficiency as the models based on the extended mild-slope equation which has been widely used for calculation of wave transformation in shallow water. For this, the computational domain is discretized into finite elements with a single layer in the vertical direction. The velocity potential in the element is then expressed in terms of the potentials at the nodes located at water surface, and the Galerkin method is used to construct the numerical model. A common shape function is adopted in horizontal direction, and the cosine hyperbolic function in vertical direction, which describes the vertical behavior of progressive waves. The model was developed for vertical two-dimensional problems. In order to verify the developed model, it is applied to vertical two-dimensional problems of wave reflection and transmission. It is shown that the present finite element model is comparable to the models based on extended mild-slope equations in both computational efficiency and accuracy.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.1071-1074
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• 2012