• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.577-577
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• 1989

In this paper, a detail evaluation of ultimate strength of offshore unstiffened tubular members with bending and local denting damage which are subjected to combined axial force and bending moment and to component load is presented through theoretical and experimental approaches. Based upon the results obtained here, the damage effect on the ultimate strength of tubular member under combined loads and component load is investigated.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.77-86
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• 1989

In this paper, a detail evaluation of ultimate strength of offshore unstiffened tubular members with bending and local denting damage which are subjected to combined axial force and bending moment and to component load is presented through theoretical and experimental approaches. Based upon the results obtained here, the damage effect on the ultimate strength of tubular member under combined loads and component load is investigated.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.4
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• pp.44-56
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• 1989

Recently the residual strength of damaged tubulars under axial compression has extensively been investigated. However, in spite of the possibility of damage onto underwater members of offshore structures as results of collisions, dropped objects and other accidental impacts occurring in service or during fabrication or installation, no research works on the structural behaviour of damaged tubulars under combined loadings including hydrostatic pressure have been reported in the literature. In this paper, a numerical method has been proposed to estimate the residual strength of damaged tubulars under combined loadings, and then the proposed method has been substantiated with corresponding test data. A simple design equation has been derived based upon the results of the parametric study using the proposed method. The accuracy of the predictions using the derived equation is found to be a 10.1% COV(Coefficient of Variation) together with an 1. 037 mean comparing with the test data.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.4
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• pp.81-93
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• 1989

The present study attempts to develop the theoretical model for the damage estimation of offshore tubular members which are subjected to the accidental impact loads due to collision, falling objects and so on. For the reasons of the simplicity of the problem being considered, however, this paper postulates that the accidental load can be approximated to be the quasi-static one, in which dynamic effects are negelcted. Based upon the theoretical and experimental results which are obtained from the present study as well as the existing literature, the load-displacement relations taking the interaction effect between the local denting and the global bending deformation into account are presented in the explicit form when the concentrated lateral load acts on the tubular member whose end condition is supposed to be rotation ally free and axially restrained, in which membrane forces develop. Thus, the practical estimation of damage deformation for the local denting and the global bending damage of tubular members against the accidental loads is possible and also the collision absorption capability of the member can be calculated by performing the integration of the area below the given load-displacement curves, provided that all the energy is dissipated to the deforming the member itself.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.103-107
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• 1994

본 연구에서는 원통 프런지 연삭에서 비가공시간을 줄이기 위해, 공연삭시간 단축과 드레싱 신호를 이용한 숫돌 손상상태 검출에 관한 연구를 수행하였다. 연삭기의 심압대에 설치한 AE센터와 숫돌 덮개에 설치한 초음파센서를 이용해 공연삭, 공작물과 숫돌의 근접, 접촉상태를 감시하고 이에 대응해 적절히 이송속도를 제어했다. 그리고 드리싱시 나타나는 AE 신호의 표준편차를 이용해 숫돌의 손상상태를 검출해서, 드레싱 기회에 대한 효과적인 정보를 제공합으로써 비가공 시간을 단축했다.

• Bulletin of the Society of Naval Architects of Korea
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• v.27 no.1
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• pp.24-34
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• 1990

In this paper, the formulation of a new simplified finite element is made to analyze the ultimate strength of damaged tubular members subjected to combined axial force and end moment. A damaged tubular member that has the bending deformation and the local dent is modeled by beam elements. Tangent elastic stiffness matrix of a beam element which contains the effect of the geometric nonlinearity is derived by using the updated Lagrangian approach. Here the contribution of the stiffness in the dented area is neglected since its resistance against the external loads is considered to be small. A fully plastic interaction curve of the element under combined loads taking account of the local dent effect is selected as a yielding criterion at each nodal point. Also tangent elasto-plastic stiffness matrix of the element is formulated by plastic node method. Comparison with the present solution and the existing experimental results is made showing that the present method gives quite an accurate solution.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.118-124
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• 1989

In this paper a design formula has been proposed to predict the residual strength of damaged tubulars subjected to combined axial copression, hydrostatic pressure and end bending loadings. A theoretical analysis method was employed to calculate the residual strengths, in which the geometric configuration of damaged tubulars is realistically described using empirically derived equations. The predictions using this method have been compared with relevent experimental results to demonstrate their validity and accuracy. A rigorous parametric study has been conducted using the method, and then a design formula has been derived based upon the parametric study results.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.618-618
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• 1989

In this paper a design formula has been proposed to predict the residual strength of damaged tubulars subjected to combined axial copression, hydrostatic pressure and end bending loadings. A theoretical analysis method was employed to calculate the residual strengths, in which the geometric configuration of damaged tubulars is realistically described using empirically derived equations. The predictions using this method have been compared with relevent experimental results to demonstrate their validity and accuracy. A rigorous parametric study has been conducted using the method, and then a design formula has been derived based upon the parametric study results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.12 s.243
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• pp.1586-1596
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• 2005

In this paper, a structural damage identification method (SDIM) is developed to identify the line crack-like directional damages generated within a cylindrical shell. First, the equations of motion for a damaged cylindrical shell are derived. Based on a theory of continuum damage mechanics, a small material volume containing a directional damage is represented by the effective orthotropic elastic stiffness, which is dependent of the size and the orientation of the damage with respect to the global coordinates. The present SDIM is then derived from the frequency response function (FRF) directly solved from the equations of motion of a damaged shell. In contrast with most existing SDIMs which require the modal parameters measured in both intact and damaged states, the present SDIM may require only the FRF-data measured at damaged state. By virtue of utilizing FRF-data, one may choose as many sets of excitation frequency and FRF measurement point as needed to acquire a sufficient number of equations for damage identification analysis. The numerically simulated damage identification tests are conducted to study the feasibility of the present SDIM.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2003.10a
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• pp.38-43
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• 2003

증기발생기 전열관의 마멸은 유체 유발 진동(flow induced vibration)에 의한 전열관과 증기발생기 상부 지지구조물 사이에서 발생하게 되며 원통 지지대(stay cylinder)상부의 중앙 공공(central cavity) 주변에 집중적으로 발생되는 것으로 보고되고 있다. 국내에서는 1997년 영광 4호기의 증기발생기에 마멸 손상이 보고된 이후 영광 3호기와 울진 3, 4호기에서도 마멸 손상이 발견되고 있으며, 외국에서는 1992-1993년 기간동안 대략 500∼600 개의 전열관이 마멸에 의해 관막음(p1u99ing)된 것으로 보고되었다.(중략)