• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.70-81
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• 2019

An improved three dimensional Rankine source method is developed to solve numerically water wave problems in time domain. The free surface and body surface are both represented by continuous panels rather than a discretization by isolated points. The integral of Rankine source 1/r on free surface panel is calculated analytically instead of numerical approximation. Due to the exact algorithm of Rankine source integral applied on the free surface and body surface, a space increment free surface source distribution method is developed and much smaller amount of source panels are required to cover the fluid domain surface than other numerical approximation methods. The proposed method shows a higher accuracy and efficiency compared to other numerical methods for various water wave problems.

• 한국해양공학회지
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• 제8권2호
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• pp.80-92
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• 1994

The dynamic response characteristics of a floating ocean city are examined for presenting the basic data for the design of huge offshore structures supported by a large number of floating bodies in waves. The numerical approach which is accurate in linear system is based on combination of a three dimensional source distribution method, wave interaction theory and the finite element method of using the space frame element. The hydrodynamic interactions among the floating bodies are taken into account in their exact form within the context of linear potential theory in the motion and structural analysis. The method is applicable to an arbitrary number of three dimensional bodies having any individual body geometries and geometrical arrangement with the restriction that the circumscribed, bottom-mounted. Imaginary vertical cylinder for each body does not contain any part of the other body. The validity of this procedure was verified by comparing with experimental results obtained in the literature.

• 동력기계공학회지
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• 제14권5호
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• pp.48-55
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• 2010

When a large ship is advancing in waves, ship undergoes the hydroelastic response, which has influences on structural stability and the fatigue destruction etc. of the ship. Therefore, to predict accurate hydroelastic response, it is necessary to analyze hydroelastic response including fluid-structure interaction. In this research, a ship is divided into many hull elements to calculate the fluid forces and wave exciting forces on each elements using three-dimensional source distribution method. The calculated fluid forces and wave exciting forces are assigned to nodes of hull elements. The neighbor nodes are connected with elastic beam elements. We analyzed hydroelastic responses, and those are formulated by using finite element method. Particularly, to estimate the influence of forward speed on the hydroelastic responses, we use two different methods : Full Hull Rotation Method(FHRM) and Sectional Hull Rotation Method(SHRM).

• 동력기계공학회지
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• 제14권2호
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• pp.48-54
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• 2010

An improved numerical scheme, to which the hydroelastic method is adapted, is introduced for predicting the motion and structural responses of tension leg platforms(TLPs) in regular waves. The numerical approach in this work is based on a combination of the three dimensional source distribution method and the finite element method. The hydrodynamic interactions among TLP members, such as columns and pontoons, are included in the motion and structural response analysis. The drag forces on the submerged slender members, which are proportional to the square of relative velocity, are included in order to estimate the responses of members with better accuracy. Comparisons with other results verify the works in this paper.

• 한국해양공학회지
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• 제7권1호
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• pp.133-146
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• 1993

A numerical procedure is described for predicting the motion and structural responses of tension leg platforms (TLPs) in waves. The developed numerical approach is based on combination of a three dimensional source distribution method and the dynamic response analysis method, in which the superstructure of TLPs is assumed flexible instead of the rigid body assumption used in usual two-step analysis method, proposed by Yoshida et. al. .The hydrodynamic interactions among TLP members, such as columms and pontoons, are included in the motion and structural analyses. Numerical results are compared with the experimental and numerical ones, which are obtained in the literature, of the motion and structural responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.

• 한국해양공학회지
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• 제13권4호통권35호
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• pp.19-27
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• 1999

To design a very large floating structure, such as a floating airport, we have to estimate the hydroelastic responses of a very large floating structure (VLFS) exactly. We developed the numerical method for estimating the hydroelastic responses of the VLFS. The developed numerical approach is based on a combination of the three-dimensional source distribution method, the wave interaction theory and the finite element method for structurally treating the space frame elements. The Numerical results of the hydroelastic responses and steady drift forces of a somisubmersible type offshore structure, which is supported by the 33(3 by 11) floating bodies, with various bending rigidities are illustrated.

• 한국해양공학회지
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• 제9권1호
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• pp.161-172
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• 1995

A numerical procedure is described fro predicting the motion and structural responses of tension leg platforms(TLPs) in waves. The developed numerical approach is based on a combination of a three dimensional source distribution method and the dynamic response analysis method, in which the superstructure of TLPs is assumed flexible instead of the rigid body assumption used in tow-step analysis method. Both the hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural whole structure are formulated using element-fixed coordinate systems which have the origin at the node of the each hull element and move parallel to a space-fixed coordinate system. Numerical results are compared with the experimental and numerical ones, which are obtained in the literature, concerning the motion and structural responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.

• 한국해양공학회지
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• 제11권4호
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• pp.76-89
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• 1997

The hydrodynamic interaction characteristics between multiple floating bodies of semisubmersible type are examined to present the basic data for the design of huge offshore structures supported by a large number of the floating bodies in multi-directional irregular waves. The numerical approach is based on a combination of a three-dimensional source distribution method, the wave interaction theory and the spectral analysis method. The effects of wave directionality on the wave exciting forces acting on multiple floating bodies in multi-directional irregular waves also have been pointed out.

• 동력기계공학회지
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• 제8권4호
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• pp.49-56
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• 2004

To design very large ships, such as very large drillships, we have to estimate the hydroelastic responses of the very large ships in waves. A numerical procedure is described for estimating the hydroelastic responses of very large ships advancing with slow speed in waves. The developed numerical approach is based on a combination of the three-dimensional source distribution method and the finite element method, including fluid-structure interaction by regarding a very large ship as many hull elements connected with elastic beam elements. Numerical results are compared with experimental and numerical ones obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

• 대한조선학회논문집
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• 제29권3호
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• pp.33-44
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• 1992

2차원 및 3차원 sloshing 문제의 해석을 위해 수치기법들을 적용하여 보았다. 2차원 탱크 내의 유동을 source 분포법과 유한차분법을 이용해 해석하였고 실험과 선형해의 결과와 비교하였다. 이 방법들의 계산결과에는 큰 차이를 발견하지 못하였고, 다만 유한차분법을 이용하는 경우 탱크 내의 내부재에 대한 고려가 용이하나 계산시간이 많이 소요되었고 source 분포법을 이용하여 해석하는 경우에는 3차원으로의 확장이 용이하나 내부재의 고려와 대진폭 운동에 대해서는 적용하기 힘들 것으로 판단된다. 3차원 문제는 source 분포법을 이용하여 해석하였고 계산모델은 사각형 및 구형탱크이다. 그러나, 이러한 sloshing 해석기법을 보다 실용적으로 사용하기 위해서는 유체의 충격력에 대한 많은 연구가 있어야 할 것으로 사료된다.