• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.192-197
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• 1995

소재의 손실을 최소한 줄이면서 원하는 형상의 제품을 가공하는 가장 기본적인 금속 가공 방법은 금형을 이용하는 금속 성형(metal forming)이다. 본 논문에서는 준정적 금속 성형 문제 해석 에대한 외연적 시간 적분 유한 요소법의 적용성을 평가 하기 위하여 변형모드가 복잡한 박판튜브 (thin-walled tube)의 좌굴문제를 해석하여 변형과정이 이론 및 실험결과와 비교적 잘 일치하는지 살펴보기로 한다. 또한 준정적 금속 성형 문제 해석에 외연적 시간 적분 유한 요소법을 사용할 때 계산 시간을 줄이기 위하여 많이 사용되는 가압속도 조절법(loading velocity control technique) 의 타당성을 평가하기 위하여 박판 튜브와 중실 실린더(solid cylinder)의 변형 속도에 따른 변형 모드의 변화를 비교 관찰하여 기하학적 형상에따른 가압속도 조절법의 적용 가능 여부를 분석하여 보겠다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.424-429
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• 2000

In this paper, the characteristics of the asymmetric coupled microstrip(ACM) lines with finite metalization thickness are investigated using the quasi-static analysis in the multilayered structure. By mode-matching method as the quasi-static analysis. the characteristic impedances and effective dielectric constants in ACM lines are obtained as a function of metalization thickness. The numerical results show that the propagation characteristics of ACM lines in the single and multilayered structure will be changed by the variation of metalization thickness.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.402-407
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• 2001

Sensitivity analysis scheme is developed in the elasto-plastic finite element method with explicit time integration using direct differentiation method. The direct differentiation is concerned with the time integration, constitutive relation, shell element with reduced integration and the contact scheme. Sensitivity analysis results are mainly examined with the highly nonlinear and quasi-static problem with the complicated contact condition. The result shows stable sensitivity especially in the sheet metal forming analysis.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1990.06a
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• pp.389-392
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• 1990

• Tunnel and Underground Space
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• v.12 no.3
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• pp.179-188
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• 2002

This study is to understand the effect of the vibration and the stress changes due to the excavation of 2 arch parts of a tunnel, which is a Gyungbu Express Railway tunnel, on the tunnel itself and adjacent slopes in advance, and to analyze the stability. For the estimation of ground conditions, borehole tests, borehole camera logging and seismic logging were performed. Ground properties at a specific location were determined as input constants by performing 2 dimensional analyses with possible ranges of uncertain ground properties. Static and pseudo-static (due to blasting vibration) factors of safety were calculated. The behavior of the tunnel and its vicinity due to the tunnel excavation were predicted by 3 dimensional analyses. It was also tested whether the support system was proper.

• Journal of the Korea Convergence Society
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• v.4 no.2
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• pp.21-27
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• 2013

Spot welding is automation of assembly process, without increasing the vehicle weight and economy, there is a fuel economy improvement of motor vehicles and to widely used in the automotive industry. But By irregular load from the road surface while at the vehicle is running, stress concentration occurs in the weld point, fatigue failure occurs frequently. Considering change of stiffness is the essential fatigue life of the evaluation spot weld. In this paper, by performing a linear static analysis was to understand the vulnerable part. Acquire to the fatigue properties of the spot weld, take the load history of the three levels in the time domain, was performed by setting as a condition of quasi-static fatigue analysis. and Fatigue life prediction method of the spot weld was by applying the method according to the fatigue damage accumulation and the conventional method was compared analyzed with the results shown.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.1
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• pp.13-25
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• 2012

The purpose of this study was to investigate the seismic behavior of hollow circular reinforced concrete bridge columns with confinement steel, and to develop improved seismic design criteria. Three hollow circular columns were tested under a constant axial load and a quasi-static, cyclically reversed horizontal load. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. The numerical method used gives a realistic prediction of the seismic performance throughout the loading cycles for the several test specimens investigated. Based on the experimental and analytical results, design recommendations are presented to improve current practice in the design and construction of hollow circular reinforced concrete bridge columns.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.81-90
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• 2011

The purpose of this study was to investigate the seismic performance of reinforced concrete bridge columns with interlocking circular hoops. Three interlocking columns were tested under a constant axial load and a quasistatic, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. The used numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated. Based on the experimental and analytical results, design recommendations are presented to improve the existing practice in the design and construction of reinforced concrete bridge columns with interlocking circular hoops.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.3
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• pp.47-55
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• 1990

This paper presents the quasi-static mooring analysis model for a vessel moored at the quay. The results of this analysis will aid the designer in determining the mooring configuration for the surface vessels subjected to wind, current and wave forces. And it will also help him in selecting the equipment for the fixed mooring system. The cumulative elastic behavior of the mooring lines invokes a complicated nonlinear problem since the mooring lines are relatively short and hang in air as noncoplanar configurations. This nonlinear mooring problem is solved in this paper by the load increment technique in which the external load is increased step by step taking all sources of nonlinearity into account.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.691-697
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• 2011

In this study, the vessel collision protective structure and the vessel were modeled numerically and the quasi-static collision analysis was performed to evaluate the maximum protection capacity. In the modeling process of protective structure, the nonlinear behaviors of structure and the supporting conditions of ground including pull-out action were considered. In that of collision vessel, the bow of vessel was modeled precisely, because of the nonlinear behaviors were concentrated on it. For the efficient analysis, the mass scaling scheme was applied, also. To evaluate the differences and efficiency, the dynamic analyses were performed for the same model, additionally. Based on the obtained energy dissipation curves of the structure and the vessel, the moment that the collision force affected to the bridge substructures was determined and the maximum allowable collision velocity was evaluated. Because of the energy dissipation bound can be recognized clearly, this scheme can be used efficient in engineering work.