• Journal of the Society of Naval Architects of Korea
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• v.39 no.2
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• pp.28-33
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• 2002

The characteristics of hull-pieces are large quantity, comparatively large piece-size, and different each shape. For the more, in the forming process(including Line-Heating Process) of curved hull pieces, shape checking processes including initial shape measurement and forming shape measurement of the each pieces are needed to achieve a given accuracy. So, the forming process of large curved hull pieces needs efficient measurement and comparison technique to check the shape and ensure the forming-accuracy In this paper, we try to construct integrated S/W, H/W system for efficient measurement and comparison of large curved hull pieces, which can apply to above forming environment.

• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.159-165
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• 2003

A tubular member with through-gusset plate is often used to transmit axial compression in an electric transmission towers. In current code, the strength of tubular member is evaluated with an effective length factor k=0.9 without considering the deformation of boundary element. A buckling strength of member with end gusset plate is affected by stiffness ratio($\beta$) and the length ratio(G) between main tubular member and end gusset plate. In this study theoretical mechanism based on the elastic buckling behavior was investigated, and finite element analysis was performed to propose a formula for the buckling strength and effective length factor of tubular member in elsatic and inelastic ranges.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.119-128
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• 1994

Deflection estimation at engine room upper deck panel is performed for the actual ship structure. These deflection behaviours are basically investigated from not only the data based on the full series results of nonlinear analysis using Incremental Galerkin's Method but also actual deflection data measured from damaged ship under construction in dry dock. The effects of residual stress, initial deflection and static loading are also included. The computed estimation results of upper deck plate panel including theme effects are shown that upper deck platings of new ship expected less deflection magnitude than damaged ship.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.3
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• pp.301-308
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• 1985

본 논문에서는 불규칙 하중을 받는 부재에 대한 연구의 고초로서 간단한 응력 모델을 설정하고 이들 변동응력이 가해지는 시기를 명확히 구분하여 크랙전파곡선의 거동을 고찰하였다. 특히 부하되는 응력 진폭의 크기에 따라서 크랙선단부의 미시적 인 변화의 크기가 다르고 이로인하여 크랙전파에 대한 피해의 정도가 달라진다고 하면 크랙전파의 지연 및 가속현상이 나타날 것이 예측이 되고 따라서 이때 나타나는 피해 정도의 크기를 미소 경도치로 환산하여 그것과 피로크랙 전파 특성과를 비교 검토 하 였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.2
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• pp.99-112
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• 2013

This paper presents a subspace system identification for estimating the stiffness matrix and flexural rigidities of a shear building. System matrices are estimated by LQ decomposition and singular value decomposition from an input-output Hankel matrix. The estimated system matrices are converted into a real coordinate through similarity transformation, and the stiffness matrix is estimated from the system matrices. The accuracy and the stability of an estimated stiffness matrix depend on the size of the associated Hankel matrix. The estimation error curve of the stiffness matrix is obtained with respect to the size of a Hankel matrix using a prior finite element model of a shear building. The sizes of the Hankel matrix, which are consistent with a target accuracy level, are chosen through this curve. Among these candidate sizes of the Hankel matrix, more proper one can be determined considering the computational cost of subspace identification. The stiffness matrix and flexural rigidities are estimated using the Hankel matrix with the candidate sizes. The validity of the proposed method is demonstrated through the numerical example of a five-story shear building model with and without damage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.567-576
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• 2023

In general, RC beam members are designed as flexural members, considering only the bending load. However, in actual buildings, axial and bending load are simultaneously applied due to the continuity between members. As a result, the bending strength of the RC beam member increases, but the displacement decreases, and cracks are mainly concentrated in the center of the beam. Therefore, in this study, the bending performance of both normal and strengthened RC beam using carbon fiber sheets subjected to combined axial and bending load was experimentally evaluated. The carbon fiber sheets were wrapped around the middle of the specimens, and axial and bending load were applied simultaneously to the beams. The magnitude of the axial force and the effects of carbon fiber sheet reinforcement on the deformed shape, bending strength, deflection, and ductility of the RC beams were analyzed. The results show that as the applied axial force increased, the maximum bending strength increased, but the ductility decreased 64%. The bending strength of the strengthened beams increased up to 27%, the maximum deflection decreased around 8% and the ductility increased by up to 43%.

• Computational Structural Engineering
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• v.10 no.4
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• pp.22-29
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• 1997

본 기사에서는 경사케이블의 자중의 현 방향성분을 고려하여 케이블의 동적 강성 행렬을 유도하였다. 이 동적 강성 행렬로부터 부재 자체의 동적특성을 자세히 파악할 수 있을 뿐만 아니라 다른 구조물과 결합되었을 경우 동해석에 소요되는 시간을 대폭적으로 줄일 수 있고 거동을 예측할 수 있다는 장점이 있다. 유도된 동적 강성값을 다른 연구결과와 비교해본 결과, 실 구조물의 부재롤 사용되는 경사 케이블은 중량이 비교적 크기 때문에 현 방향 자중성분을 무시할 수 없으며 항상 복합 모드 현상을 보인다는 것을 알았다. 또한 이러한 복합 모드형성으로 인해 경사 케이블의 동적 강성값은 기존의 동적 강성값보다 좀 더 큰 값을 보인다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.395-401
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• 2010

The vertical members of structures are shortened as time goes on. Because structures have been high-rising and atypical there should be different axial loads among vertical members and it causes differential column shortenings. The differential column shortening add stresses to connections, make slab tilt, and damage to non-structural components. To reduce these influences compensation is need. The rational compensation means the exact expectation of amounts of column shortenings and the reasonable corrections. The expectation of column shortenings are more exact as researched, however, there is little research about the compensation. This paper presents the average correction method and the constraints for differential column shortenings considering errors due to the construction precision. The relations between constraints and the number of correction groups give an objective criterion for decision of constraints.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.2
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• pp.29-36
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• 1987

In most of the structural members with initial cracks, the strength tends to decrease as the member size increases. This phenomenon is known as size effect. Among the structural materials of glass, metal or concrete, etc., concrete represents the size effect even without initial crack. According to the previous size effect law, the concrete member of very large size can resist little stress. Actually, however, even the large size member can resist some stress if there is no initial notch. This means that the fracture mechanism of very small or very large size member follows strength criterion, but the medium size member follows non-linear fracture mechanics (NLFM). In this study, the empirical models which are derived based on nonlinear fracture mechanics are proposed according to the regression analysis with the existing test data of large size specimens for uni-axial compression test, splitting tensile test and shear test of reinforced concrete beams.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5910-5916
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• 2011

Surface area of the steel member exposed to fire differs according to type and size of the section and the kind of the member, which shows a big difference in the temperature rise of the steel by fire. The section factor ($H_p$/A) is determined by factors such as type, size, and member of the steel and type of the fire protection material, and it is the criteria in determining thickness of the fire protection material. This study showed that the size of the steel increase regardless of the steel type, the section factor decrease. In the results on fire protection thickness of the steel according to the section factor, the efficiency of 1 hour fire protection was lower from 30 to 50% than the criteria. And there is the member, which have the thickness lower the minimum 27% in 2 hour fire protection, but it generally approached in the criteria. In case of H-shape steel, the efficiency of 3 hour fire protection was suitable for the criteria, but rectangular hollow steel section and circular hollow steel section were higher (5.0-17.5%) than the criteria.