• Journal of the Korean Society of Safety
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• v.7 no.4
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• pp.55-61
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• 1992

An engineer designing a tunnel in an urban area should be to predict the magnitude and distribution of ground movements which are important to Investigate the potential damage to the existing structures around tunnel. The present study examines available theories and emprical equations, and tries to investigate quantativily ground movements around tunnel with tunnel progressing. Approcaches to the problem of ground movements associated with twin tunnel was and elasto - plastic finite element method. Typical section in Seoul Subway were selected in numerical study. The analysis and study was done with respect. to surface, subsurface and crown settlements with varying ground conditions, tunnel geommetry and construction conditions.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.280-282
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• 2006

Prediction and control of the thermal distortion is particularly important for the design and manufacture of welded thin plate panel. In this study, experiments and computations are peformed to analyze how hole configuration and the size of the specimen effect on distortion. In addition, this study aims to develop a thermal elasto-plastic simulation using finite element method to predict distortion, with particular emphasis on buckling deformation generated in attachments welded around hole.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.163-168
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• 1994

Zinc coated steel sheets have been widely used in automotive industry. High power laser welding has been used as an excellent welding means for thin sheets. The welding residual stress, which was brought in laser welding, causes making weak the mechanical strength. The purpose of this study is to get the residual stress distribution in various laser welding condition by FEM and verify the results by X-Ray diffraction. Welding residual stresses have been calculated by thermal elasto-plastic analysis using finite element method. Form the results, it can be known that the laser welding condition affects to distribution of the residual stress.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.93-100
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• 2002

Vertical reinforcement of soft soils using the deep mixing method has received increasing applications. In this study, the theory of elasticity and plasticity including the upper bound theorem of limit analysis were used to derive the equations for obtaining composite elastic properties and shear strength parameters. The developed equations were validated using the finite element computer program SAGE CRISP. The analysis involved 4 different cases-two different type of soil and replacement ratios. Tile results of the analysis show that the proposed equations could determine the properties of composite material for practical applications.

• Journal of Welding and Joining
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• v.25 no.5
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• pp.72-77
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• 2007

Prediction and control of the thermal distortion is particularly important for the design and manufacture of welded thin metal structure. In this study, numerical computations are performed to analyze effect of structure section shape and weld line location on distortion. In addition, this study aims to develop a thermal elasto-plastic simulation using finite element method to predict distortion, with particular emphasis on bending deformation generated in outline welding of a thin box structure. From the numerical analysis, it was revealed that the section shape and weld line location play an important role on the welding distortion. Among 3 types of section shape design proposed in this study, the least deformation remained in the two path welded structure.

• The Journal of Engineering Geology
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• v.8 no.3
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• pp.225-234
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• 1998

The behavior of the underground opening depends mainly on the magnitude of the initial stress existing before excavation and on the stress redistribution due to the excavation. In the case of elasto-plastic materials such as rock mass, as the structural behavior of surrounded opening due to excavation depends on the stress path, methods and sequence of excavation have influences on the results of numerical analysis. Therefore, in order to design underground openings with large cross-section such as underground nuclear power plants, radioactive waste disposal cavems, oil storage caverns, and so on more reasonably it is desirable to consider the effect of the excavation sequence in the analysis. In this paper, the underground structure is analyzed using the finite element method and the distinct element methods with a view to review the the effect of the excavation sequence. Based on the results of the analysis the followings are discussed : influence of excavation shape and sequence, effect of structural reinforcements, influence of multi caverns.

• Journal of the Korean Geosynthetics Society
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• v.21 no.2
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• pp.39-48
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• 2022

Unlike the horizontal strut, the corner strut causes bending behavior by the installation angle when soil pressure occurs, so there is a limit to its application as a elasto plastic method that requires only the axial stiffness of struts. Therefore, this study attempted to approach a method of modifying axial stiffness data to present an analysis method for corner struts in elasto plastic method, and linear elasticity analysis was used for this. And, through Linear elasticity analysis, axial stiffness data for corner struts installed at the actual site were calculated. The behavior of the retainingwall was confirmed by applying the calculated axial stiffness data of corner struts to elasto plastic method, and its applicability was evaluated by comparing it with the measurement results and the finite element analysis results. As a result of the study, when the axial stiffness data of the corner struts was applied using Linear elasticity analysis(Case 1, Case 3), the axial stiffness data decreased to 9% to 17% compared to the general method of applying the axial stiffness of the struts(Case 2, Case 4), and the displacement of the retainingwall increased to 25.33% to 64.42%. Comparing this result with the measurement results, when Linear elasticity analysis was used(Case 1, Case 3), the behavior of the retainingwall during the elasto plastic method was better shown.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.490-496
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• 2006

In order to design accurately plastic board drain (PBB) method, it is important to determine the equivalent circle of PBD. In this paper, a series of numerical analyses on soft ground improved by PBD were carried out, in order to investigate the resonable equivalent circle of PBD considering consolidation behavior of improved soft ground by PBD. The applicability of numerical analyses, in which an elasto-viscoplastic three-dimensional consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of soft ground improved by PBD. And, through the results of the numerical analyses, consolidation behaviors of soft ground during consolidation was elucidated, together with the equivalent circle of PBD considering consolidation behaviors.

• Journal of Welding and Joining
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• v.32 no.4
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• pp.69-74
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• 2014

Welding distortions of large steel structures had mainly been estimated with some simplified formula obtained by lots of experience and numerical analyses for small steel structures. However, the large structures would have different characteristics of distortion with welding because of their own stiffness coming from the size itself. Therefore, in order to find some measures for preventing welding distortion of large structure, it is requite in advance to precisely analysis thermal stress and distortion during welding of the structure. Numerical analysis for larger structure has been known to take large amount of calculation time and have a poor convergency problem during the thermo-elasto-plastic calculation. In this study, a hybrid method is proposed to analysis the thermal stress and distortion of a large steel plate with the finite element analysis by incorporating with temperature distribution of the plate calculated by an analytical solution. The proposed method revealed that the thermo-mechanical analysis for welding of the large structure could be performed with a good convergence and produced precise results with much reduced time consumption.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1551-1562
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• 1991

최근까지 발표된 유한 요소법을 이용한 압연 해석 관련 주요 논문들을 정리해 보면 다음과 같다. Li와 Kobayashil는 강소성 유한 요소법(rigidplastic finite element method)을 여러가지 마찰조건에 대하여 해석하였다. 이때 압연롤은 강체 (rigid body)로 시편은 가공경화(workhardening)를 동반한 강소성체로 모델링하였다. Hwang과 Kobayashi는 강소성 유한 요소법을 이용한 평면 변형 압연에서 재료 손실을 최소화하는 예비 성형체(preform)의 설계에 대한 연구를 수행하였다. 이 경우에도 역시 압연롤은 강체로 시편은 가공 경화를 동반한 강소성체와 완전 소성체로 모델링 되었으나, 고착(sticking) 마찰 조건에 대해서만 해석을 수행하였다. Mori와 Osak- ada 그리고 Oda는 약간 압축성이 있는 재료의 평면 변형 압연에 대하여 연구하였다. 이때 압연롤은 강체로 시편은 가공 경화를 동반한 강소성체로 모델링 되었으며 경계 면에서는 Coulomb 마찰을 고려하였다. 이밖에도 오일러(Eulerian) 수식화를 이용한 Dawson과 Thompson, Berman의 해석 결과가 있으며, 또 폭 방향의 변형까지를 고려한 Li와 Kobayashi, Mori와 Osakada의 3차원 해석 결과가 있다.