• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.133-133
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• 2004

박막이나 초미세 구조체의 경도 및 탄성계수 측정을 위한 나노 압입실험에서는 Oliver ＆ Pharr가 제안한 하중-변위 측정 나노압입법이 널리 쓰이고 있다 위 실험법에서, 나노경도(nano-hardness; H$_{n}$)는 최대하중을 계산된 접촉면적 (A$_{c}$)으로 나누어 평가하고, 압입자 및 박막의 탄성성질을 포함하는 환산 탄성계수 (reduced modulus ; E$_{r}$)는 하중제거곡선의 초기 기울기인 접촉탄성강성 (S)를 이용하여 계산한다. 그러나, 하중-변위 측정 나노압입법에서는 탄성 및 소성변형만이 고려되고 시간 의존적 변형거동 (time dependent deformation; TDD)은 고려되지 않는다.(중략)

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.2
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• pp.161-169
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• 1999

이방성체의 평면내 직선균열에 대한 균열선단부근의 응력과 변위의 분포는 어떠한 균열체의 형상 및 하중조건에 대해서도 응력확대계수라는 하나의 매개변수로서 나타낼 수 있다고 하는 것이 파괴역학에서 보편화되어 있다. 그러나 많은 경우에 있어서 급수전개식의 이어지는 항은 정량적으로 중요하다. 따라서 본 연구에서는 이러한 항을 유도하고 이것이 균열진전방향에 미치는 영향에 대하여 검초하였다. 이를 위하여 단축하중을 받는 직방성균열체의 해석을 수행하며 재료는 균질이방성체라고 가정하였다. 급수전개식에서 2차항의 영향을 고려하기 위하여 균열선단에서의 응력의 분포를 재해석하였으며, 2차항의 사용은 정확한 균열진전방향의 결정을 위해서 매우 중요함을 보였다. 초기균열진전각도의 결정을 위해서 수직응력비이론을 적용하였다.

• Computational Structural Engineering
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• v.11 no.1
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• pp.179-190
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• 1998

A geometrically nonlinear finite element formulation of spatial cable networks is presented using two cable elements. Firstly, derivation procedures of tangent stiffness and mass matrices for the space truss element and the elastic catenary cable element are summarized. The load incremental method based on Newton-Raphson iteration method and the dynamic relaxation method are presented in order to determine the initial static state of cable nets subjected to self-weights and support motions. Furthermore, static non-linear analysis of cable structures under additional live loads are performed based on the initial configuration. Challenging example problems are presented and discussed in order to demonstrate the feasibility of the present finite element method and investigate static nonlinear behaviors of cable nets.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.359-364
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• 1996

'93.4월에 고리원자력 4호기 운전중(원자로 출력 100%, 발전기 출력 975MWe) 주증기 차단밸브 (MSIV)의 닫힘으로 인해 발전소가 정지되었다. 밸브분해 점검결과 밸브스템이 Back Seat Ring 조립부위 Notch 부위에서 Steam Flow와 평행한 방향으로 절단되어, 밸브스템의 손상원인을 규명하기 위한 본 연구에서는 피로해석절차도에 따라 S-N 곡선에 근거하여 피로해석을 수행하였다. 피로해석결과 밸브스템의 초기균열 생성원인은 Stem Notch 부위의 제작결함과 발전소 정지시 밸브를 급속히 닫을 때 작용하는 충격하중등에 의해 발생된 것으로 추정되며 인장평균응력과 관내 유체의 진동하중의 변동응력이 조합하여 피로균열을 가속시켜 파손을 일으킨 것으로 사교된다.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.855-858
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• 2008

The lightweight bubble mixture soil are lightweight soft ground rear, which is used with the material filling. However, comparing with the general soil, it is not valuably useful from domestic. The utilization of the general soil which initial public corporation holds mainly few. The overlay method of general soil decreasing the number of layers increases according to use research study. From the research which consequently, BOX mechanical behavior materials rear executed LCC analyses the general soil which is a material filling and lightweight bubble mixture soil, discussed two kind alternatives and presents the analysis will be able to support the decision-making which is rational from the economics. The expense, which results from the resultant of lightweight bubble mixture soil maintenance, was fewer and was then analyzed with the fact that, will be able to secure an economical efficiency within 6 years.

• Korean Journal of Construction Engineering and Management
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• v.10 no.6
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• pp.40-47
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• 2009

The lightweight bubble mixture soil is used for soft ground rear-filling material by applying reduced weight on structure. However, comparing with the general soil, it is not applied in domestic because of initial phase cost of construction. General soil, which has lower initial phase cost is usually used for rear-filling, but the use of overlay method of general soil is reduced as the number of layers increases. Especially box structure placed in soft ground or the overlay method when gap near pier rear-filling can be replaced with temporary alternative method, however, it can't be a solution to gap by generation of extra weight of thickness of overlaying. Therefore, execute LCC analysis of two alternative-the general and the lightweight bubble mixture soils, which are rear-filling material of box structure- and present economical analysis in order to make resonable decision from the economics. As a result, although the lightweight bubble mixture soil takes higher initial phase cost than the general soil, it has been analyzed to procure economical efficiency by having less cost of maintenance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4216-4222
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• 2011

In this study the inelastic behavior of the existing school buildings with infilled masonry walls is analysed by pushover method. The shear stiffness and strength of masonry wall is calculated from the prior experimets and verified by inelastic analysis. The height of infilled masonry wall affects the structural behavior. The higher the masonry wall height, the higher the initial shear stiffness and strength of masonry wall. As the cracks are developed, the strength of masonry wall is much decreased. The proposed inelastic analysis method shows similar results with the experiments and can be used as inelastic analysis model of reinforced concrete buildings with infilled masonry walls.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.317-324
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• 2022

In this paper, an analysis method that considers the initial static displacement of structural members using an equivalent single-degree-of-freedom system is presented. Newmark's dynamic analysis algorithm was improved to consider the effect of the initial static displacements of structural members. The effect of the initial static displacement on the maximum response according to the assumed duration of the blast load and natural period of the member was investigated. The effects of positive and negative static displacements on the maximum dynamic responses of structural members subjected to a positively applied blast load were also studied. Modified response charts for the shock-type and pressure-type waves are presented so that static displacements can easily be considered. Using a design example, we demonstrate the significance of the modified response chart that considers the static displacement. Based on the results of this study, the maximum response of a the structural member can be easily obtained whilst considering its initial static displacement. The modified response chart presented in this study can be used for the structural design of plants and military facilities.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.2
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• pp.86-90
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• 1994

This paper attempts to incorporate the initial crack damage effect into the existing idealized plate unit. For this purpose, a new concept which indicates the equivalent, reduced material properties due to initial cracks at the structural unit level, not at he microscopic aspect, is suggested, and a simplified mechanical plate model for the initially cracked plate in axial tension is formulated as a function of initial crack length, based on the finite-element solutions obtained by crack propagation analysis.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.2
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• pp.1-14
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• 2009

Ductility-based seismic design is strongly required for the rational and cost-effective design of RC piers, and a reliable evaluation of shear strength is indispensable for its success. Unlike the flexural behavior of RC columns, shear behavior is highly complex, due to its many effects such as size, aspect ratio, axial force, ductility and so on. To address this, many design and empirical equations have been proposed considering these effects. However, these equations show significant differences in their evaluation of the initial shear strength, and the reduction in strength with the increase of ductility. In this study, the characteristics of initial shear strength of hollow sectional columns were investigated using experiments with the parameters of aspect ratios, void ratios, web area ratios and load patterns. The test results were analyzed through a comparison with the values predicted by empirical equations. On the basis of the mechanical characteristics and test results, a new empirical equation was proposed, and its validity was assessed.