• Journal of Power System Engineering
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• v.14 no.1
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• pp.53-58
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• 2010

A three-dimensional source distribution method is presented for the prediction of motions and vertical bending moments of ships travelling with forward speed in regular waves. Comparisons between theoretical and experimental results are shown for the motion responses and vertical bending moment of the S175 container ship model by Watanabe et al. The model ship was made of synthetic resins so as to simulate bending rigidity of a full scale ship. Numerical results are compared with experimental and numerical ones obtained in the literature. The results of comparison confirmed the validity of the proposed approach.

• Bulletin of the Society of Naval Architects of Korea
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• v.18 no.3
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• pp.1-9
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• 1981

In this paper, it is demonstrated that, with the distribution of lowest order concentrated(discrete) singularities of delta function nature, the solution to the linear free surface problem can be obtained with a remarkable degree of accuracy. The linear boundary value problem is formulated subject to boundary conditions for the determination of strengths of singularities; the simple sources above(not on) the free surface and the vortices on the body surface. Three sample calculation were performed` the flow about a submerged vortex of known strength, the flow past a submerged circular cylinder, and the flow around a hydrofoil section. The convergence of the numerical procedure is achieved with a relatively small number of elements. The final results are compared with those of the published works, and are considered very satisfactory.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.101-107
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• 2006

Recently, with the increase in requirements for marine development, a marine urbanism is being visualized, with more and more huge-scale structures at the scope of the ocean space utilization. In particular, a pontoon-type structure has attracted attention, since The Floating Structures Association of Japan proposed a new concept as the most suitable one of floating airports. The Very Lage Floating Structure (VLFS) is considered a flexible structure, for a quite large length-to-breadth ratio and its geometrical flexibility. The main objective of this study is to makean exact and convenient prediction about the hydro-elastic response on very large offshore structures in waves. The numerical approach for the hydro-elastic responses is based on the combination of the three dimensional source distribution method and the dynamic response analysis method, which assumed a dividing pontoon type structure, as many rigid bodies connected elastic beam elements. The established hydo-elastic theory was applied to the radiation forces caused by motions of a whole structure, formulated using the global coordinate system, which has the origin at the center of the structure. However, in this paper, we took radiation forces, occurred by individual motions of floating bodies, into consideration. The calculated results show good agreement with the experimental and calculated results by Yago.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.65-71
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• 2012

A numerical procedure is described for predicting the dynamic structural responses of tension leg platforms(TLPs) in current and waves. The developed numerical approach is based on a combination of the three dimensional source distribution method and the dynamic structural analysis method, in which the superstructure of the TLPs is assumed to be flexible instead of rigid. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in the dynamic structural analysis. The equations of motion of a whole structure are formulated using element-fixed coordinate systems which have the origin at the nodes of the each hull element and move parallel to a space-fixed coordinate system. The dynamic structural responses of a TLP were analyzed in the case of including the current or not including the one in waves and the effects of current on the TLP were investigated.

• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.83-90
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• 2006

Recently, as the technology of utilization for the ocean space is being advanced, floating structures are asked for being mare and mare huge-scale. A very large floating structure(VLFS) is considered as a flexible structure, because of a quite large length-to-breadth ratio and its geometrical flexibility. The main object of this study is to develop an accurate and convenient method on the hydroelastic response analysis of very large offshore structures on the real sea states. The numerical approach for the hydorelastic responses is based on the combination of the three dimensional source distribution methods, the dynamic response analysis method and the spectral analysis method. A model is considered as many rigid bodies connected elastic beam elements. The calculated results shaw good agreement with the experimental and calculated ones by Ohta.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.360-369
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• 2007

When a large ship is advancing in waves, ship undergoes the hydroelastic response, and this have influence on structural stability and the fatigue destruction etc. of ship. The main objective of this research is to develop an accurate and convenient method on the hydroelastic response analysis of ships on the real sea states. We analyzed hydroelastic responses, which is formulated by finite element method. The numerical approach for the hydroelastic responses is based on the combination of the three dimensional source distribution method, the dynamic response analysis and the spectral analysis method. The calculated results show good agreement with the experimental and calculated ones by Watanabe.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.4
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• pp.123-135
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• 1995

A numerical procedure is described for predicting steady drift forces an multiple three-dimensional bodies of arbitrary shape freely floating in waves. The developed numerical approach is based on combination of a three-dimensional source distribution method, wave interaction theory art the far-field method using momentum theory. Numerical results are compared with the experimental or numerical ones, which are obtained in the literature, of steady drift forces on 33(3 by 11) floating composite vertical cylinders in waves. The results of comparison confirmed the validity of the proposed approach. Finally, the interaction effects are examined in the case of an array of 40(4 by 10) freely floating rectangular bodies in shallow water.

• Journal of Periodontal and Implant Science
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• v.33 no.4
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• pp.739-745
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• 2003

Interleukine-1(IL-1)은 여러 가지 기능을 가진 싸이토카인으로써 미생물에 대한 면역반응을 일으킨다. IL-1의 유전자 다형성과 치주질환과의 관련성에 대한 많은 연구가 있어왔지만, 대부분이 백인을 대상으로 한 연구였다. 이후 중국인과 일본인을 대상으로 한 연구에서 IL-1의 유전자 다형성의 분포가 인종간에 차이를 보인다는 점이 발견되었다. 이번 연구에서는 치주적으로 건강한 한국인에서 IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN에 대한 유전자형의 분포를 조사하고자 하였다. 서울대학교 치과병원에 근무하는 치과의사, 치과위생사, 간호조무사 및 서울대학교 치과대학 4학년 학생 중 치주낭 깊이와 부착소실이 4mm 이하인 치주적으로 건강한 한국인 65명을 대상으로 하였다. IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN의 유전자 다형성은 분리한 DNA에 각 대립유전자에 특이성을 지닌 primer를 넣고 PCR(Polymerase Chain Reaction)법을 이용하여 증폭시킨후 전기영동법을 이용하여 각 대립유전자의 존재를 확인함으로써 결정하였다. IL-1${\beta}$-511 대립유전자 11, 대립유전자 12, 대립유전자 22의 유전자형에 대하여 각각 23.1%, 49.2%, 26.2%의 분포를 보였다. IL-1${\beta}$+3954의 유전자 다형성은 대립유전자 11, 대립유전자 12의 유전자형에 대하여 각각 89.2%, 10.8%의 분포를 보였으며, 대립유전자 22의 유전자형을 갖는 사람은 한명도 발견되지 않았다. IL-1RN의 유전자형은 5가지의 대립유전자 중에서 1, 대립유전자 2, 대립유전자 4만일 발견되었으며, 대립유전자 11, 대립유전자 12, 대립유전자 14의 유전자형이 86.2%, 12.3%, 1.5%로 분포하였다. 이를 바탕으로 각 대립유전자의 발생빈도 계산한 결과 IL-1${\beta}$-511에서는 대립유전자 1과 2의 비율이 거의 유사하였으나 (47.7%, 52.3%), IL-1${\beta}$+3954, IL-1RN에서는 대립유전자 1이 90%이상 발견되었으며, 또한 대립유전자 1외의 다른 대립유전자가 발견된 경우, 모두 이형접합체였다. 이 연구는 IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN에 대한 유전자형의 분포를 조사한 것으로 한국인에서 이들 유전자의 유전자형의 분포는 백인에서의 분포와 차이를 보이고 있었다. 이후 치주질환자의 유전자형 분포와의 비교로 치주질환과 IL-1${\beta}$-511, IL-1${\beta}$+3954, IL-1RN의 유전자다형성과의 관련성에 관한 추가적인 연구가 필요할 것으로 여겨진다.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.2
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• pp.49-63
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• 1989

Wave drift forces which are small in magnitudes compared to the first order wave exciting forces can cause very large motion of a vessel in waves. In this paper a theoretical and experimental analysis is made of the mean and slowly varying wave dirft forces on the semi-submersible platform. Theoretical calculations are performed by using near field method with three dimensional diffraction theory and model tests are carried out in regular and irregular waves with a 1/60 semi model. Test results are compared with theoretical calculations and the mooring spring effects in the test are discussed.

• Journal of Ocean Engineering and Technology
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• v.18 no.6 s.61
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• pp.16-21
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• 2004

This study presents the wave forces for spar platforms. The advantage of a spar platform is that it is easy to manufacture and has excellent to motion characteristics. It is important to precisely determine the wave force acting on spar platforms for their basic design of them. We measur the wave exciting force for both the classic spar and truss spar models, and accomplish the numerical calculation using diffraction theory. The results show that experimental values have good agreement with theoretical values. However it is difficult to accurately estimate the value considering the heave plate of truss spar due to the viscosity.