• Journal of the Korean Geosynthetics Society
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• v.20 no.3
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• pp.11-20
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• 2021

In this paper, the approximately coupled method of finite element method and boundary element method to obtain efficient and accurate analysis results is proposed for a two-dimensional elasto-static problem with a geometrically abruptly changing part. As the finite element of a two-dimensional problem, three-node and four-node plane stress element is applied, and as the boundary element of a two-dimensional problem, three-node boundary element is applied. In the modeling stage, firstly, an entire analysis target object is modeled as finite elements, and then a geometrically abruptly changing part is modeled as boundary elements. The boundary element is defined using the nodes defined for modeling finite elements. In the analysis stage, finite element analysis is firstly performed on a entire analysis target object, and boundary element analysis is automatically performed afterwards. As for the boundary conditions at boundary element analysis, displacement conditions and stress conditions, which are the results of finite element analysis, are applied. As a numerical example, the analysis results for a two-dimensional elasto-static problem, a plate with a crack, are presented and investigated.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.1-10
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• 2004

Adaptive finite element analysis, in which its solution error meets with the user defined allowable error, is recently used to improve the reliability of finite element analysis results. This adaptive analysis is composed of two procedures; one is the error estimation of an analysis result and the other is the reconstruction of finite elements. In the (p-method, an element size is controlled by relocating of nodal positions (r-method) and the order of an element shape function is determined by the hierarchical polynomial (p-method) corresponding to the clement solution error by the enhanced SPR. In order to show the effectiveness and the accuracy of the suggested rp-method, various numerical examples were analyzed and these analysis results were examined by comparing with those obtained by the existed methods.

• Journal of Ocean Engineering and Technology
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• v.7 no.1
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• pp.3-12
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• 1993

용접부의 파괴특성을 J-적분을 이용하여 유한요소법으로 해석하였다. 용접부 의 열전달 해석 및 응력해석을 수행한후 crack을 도입하여 crack 주위의 자류응력 해석을 통하여 crack tip에서의 J- 적분치를 계산하였다. 이차원 및 삼차원에서의 파괴해석을 위한 modeling 과정을 소개하였으며 대표적인 계산결과를 소개하였다.

• The Journal of Engineering Geology
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• v.25 no.2
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• pp.201-213
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• 2015

Site effects resulting in the amplification of earthquake ground motion are strongly influenced not only by the subsurface soil conditions and structure, but also by the surface topography. Yet, over the last several decades, most studies of site-specific seismic responses in Korea have focused primarily on the seismic amplification associated with geologic and soil conditions. For example, the effects of local geology are now well established and have been incorporated into current Korean seismic design codes, whereas topographic effects have not been considered. To help address this shortcoming, two-dimensional (2D) seismic site response analyses, using finite element (FE) ground modeling with three different slope angles, were performed in order to assess the site effects of surface topography. We then compared our results, specifically peak ground acceleration (PGA) and acceleration response spectrum, to those of one-dimensional (1D) FE model analyses conducted alongside our study. Throughout much of the upper slope region, PGAs and spectral accelerations are larger in the 2D analyses than in the 1D analyses as a result of the topographic effect.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.141-150
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• 1990

Numerical experiments of sballow water equations are performed under various boundary conditions by finite element method to simulate the circulation in estuaries and coastal areas. Galerkin method is employed to discretize spatial domain, and for time integration, finite difference method (Crank-Nicolson scheme) is used. This method is tested in five problems, in which first four cases have analytic solutions. The computed values are well in agreement with the analytic solutions in four experiments and the result of the last 2-dimensional ease is resonable. Implicit and two step Lax-Wendroff schemes in time domain are compared, and the results when using four node bilinear and triangular elements are presented. Consequently it takes very long time for complex problems requiring many elements to integrate all the time steps using the implicit schemes. And the explicit scheme requires careful consideration in selecting the time step and the grid size to obtain the desired accuracy.

• Journal of the Korean Society of Safety
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• v.23 no.3
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• pp.87-92
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• 2008

A finite element method which is discontinuous in time is developed for the solution of the classical parabolic model of heat conduction problems. The approximations are continuous with respect to the space variables for each fixed time, but they admit discontinuities with respect to the time variable at each time step. The method is superior to other well-known approaches to these problems in that it allows a wider range of moving boundary value problems to be dealt with, such as are encountered in complex engineering operations like ground freezing. The method is applied to one-dimensional and two-dimensional heat conduction problems in this paper, although it could be extended to more higher dimensional problems. Several example problems are discussed and illustrated, and comparisons are made with analytical approaches where these can also be used.

• Journal of the Korean Magnetics Society
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• v.24 no.5
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• pp.152-159
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• 2014

Magnetic gear can transmit torque without any mechanical contact among rotational parts in rotating mechanical systems. Especially, magnetic gear using rare-earth PMs can be used in variety of industry application because of their great power efficiency. Thus, recent trend shows that magnetic gear can be replaced with common mechanical gear. This paper deals with comparison and torque analysis for magnetic gears with parallel and Halbach magnetization according to various design parameters. Using a two dimensional (2D) finite element (FE) analysis, suitable gear ratio is selected. We performed analysis for magnetically connected inner and outer torque with respect to various design parameters including thickness of inner and outer PM, steel pole angle, segments of Halbach array and magnetization pattern of inner and outer PMs. Finally, we can obtain improved design model having parallel and Halbach magnetization with larger torque, compared with an initial design model.

• Composites Research
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• v.25 no.1
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• pp.1-8
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• 2012

In order to predict the thermoelastic behavior of porous composites, poroelastic parameters are measured by using micromechanics-based finite element models. The expanding deformation caused by pore pressure, and the degradation of homogenized elastic moduli with pores are calculated for the assessment of the poroelastic parameters. Various representative volume elements considering the shape, size, and array pattern of pores are modeled and analyzed by a finite element method. The effects of porosity and material anisotropy, and the distribution of stain energy density are investigated carefully. In addition, the measured poroelastic parameters are verified by predicting the thermo-pore-elastic behavior of carbon/phenolic composites.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.201.1-201.1
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• 2016

전주된 Invar (Fe-35%Ni) 박판 위에 증착된 Cu 박막은 스퍼터 전력량이 증가할수록 증착속도가 증가하였다. Cu/Invar 박판이 Invar 박판보다 면저항 값이 34%로 작았다. Invar 박판 위에 Cu가 증착되면 최대자화와 투자율은 각각 40.3, 65.0 [%] 감소하였다. Cu 박막의 탄성하강강성도, 마찰계수, 피로한계는 각각 45, 0.130, 0.093 이었다. 동적 나노 압침법으로 얻은 Invaar/Cu 박막의 하중-시간-변위 곡선의 가장 큰 차이는 탄성하강강성도(elastic stiffness) 이었다. 미세경도와 나노경도의 실험적 관계식은 $Y[GPa]=9.18{\times}10^{-3}X[Hv]$ 이었다. 나노압침선단의 하중분포를 이차원 선형 및 비선형 유한요소해석을 통하여 1.0 [mN] 의 정적하중을 가한 Cu 박막은 486 [mN] 으로 예측되었다. 이는 표면탐침현미경으로 관찰한 압흔의 변형정도와 유사한 경향을 보였다.

• Journal of Korean Society of Steel Construction
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• v.18 no.3
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• pp.373-383
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• 2006

In a steel structural system, noncomposite form deck one-way slab is the plate element supported by four-edged steel beams with unequaled stiffness. However, design criterion has analyzed the one-way slab as the continuous beam. Because the end beams that support the one-way slab have elastic supports t hat cause different deflections according to the support conditions and locations, the bending moments corresponding to the support ic support effect is not considered in the design criterion. Accordingly, to conduct a reasonable estimation of approximate moment coefficients considering the unequaled elastic support conditions, this study analyzes and estimates various models with varia bles for the ratios of live load to dead load and pattern arangements of live loads and span lengths. The analytical methods considering the finite three-dimensional plate element, the two-dimensional elastic support and the infinite stifnes suport are performed.