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스펙트랄요소법(SEM)을 이용한 파랑-조류 상호작용 현상 수치해석 연구
성홍근(Hong Gun Sung),홍기용(Key Yong Hong),경조현(Jo Hyun Kyung),홍사영(Sa Young Hong) 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.3 No.1
본 논문에서는 Freak Wave의 생성원인에 대하여 간략히 논의하였으며, 이 중 파랑-조류 비선형 상호작용에 대한 이론 및 수치적 해석기법의 역사와 장단점 등을 기술한다. 본 연구에서는 파랑-조류 상호작용에 대한 수치모델링 및 해석 기법을 개발하고 있다. 개발 중인 수치해석 기법은 공간적으로 불균일한 조류와 파랑의 비선형 상호작용을 해석하기 위하여 Navier-Stokes 방정식을 이용하여 유동현상을 모델링하였으며, 이산화를 위하여 스펙트랄요소법(Spectral Element Method; SEM)을 이용하였다. 또한 자유표면의 운동을 효과적으로 기술하기 위하여 ALE(Arbitrary Lagrangian-Eulerian)기법을 사용하였다. 본 연구의 유동 모델과 수치해석기법의 과정과 특성, 그리고 장점 등에 대하여 논의하였으며, 초기적인 수치해석 결과를 제시하였다. 이를 바탕으로 개발된 수치해석기법의 정확성 및 수렴성을 확인할 수 있다. In this paper, generation mechanisms of ocean freak waves are briefly introduced in the context of wave-current interaction phenomena. The present model of the fluid motion is based on the Navier-Stokes equations incorporating velocity-pressure formulation because of need to model the nonlinear wave interaction with spatially non-uniform current field. In order to deal with the free surface motion, an Arbitrary Lagrangian-Eulerian (ALE) description is adopted. As on accurate and efficient numerical tool, the spectral element method is presented with general features and specific treatment for the wave-current interaction problem. As an intermediate stage of development, solution procedure and characteristic aspects of the present modeling and numerical method are addressed in detail, and preliminary numerical results prove its accuracy and convergence.
파랑-조류 상호작용에 의한 Freak Wave 발생기전 수치해석 기초연구
성홍근(Hong Gun Sung),홍기용(Key Yong Hong),홍사영(Sa Young Hong) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this paper, generation mechanisms of ocean freak waves are briefly introduced in the context of wave-current interaction phenomena. As an accurate and efficient numerical tool, the spectral method is presented with general features and specific treatment for the wave-current interaction problem. Accuracy and convergence of the developed spectral method is proved to be very promising. Due to the preliminary numerical results for a linear wave-maker problem, the numerical stability of the present method is reliable. It is therefore believed that the present numerical method seems to be very promising for the understanding and analysis of the freak wave generation mechanism due to wave-current interaction.
홍도천,홍사영,성홍근,Hong, Do-Chun,Hong, Sa-Young,Sung, Hong-Gun The Society of Naval Architects of Korea 2010 大韓造船學會 論文集 Vol.47 No.3
A three-dimensional time-domain calculation method is of crucial importance in prediction of the motions and wave loads of a ship advancing in a severe irregular sea. The exact solution of the free surface wave-ship interaction problem is very complicated because of the essentially nonlinear boundary conditions. In this paper, an approximate body nonlinear approach based on the three-dimensional time-domain forward-speed free-surface Green function has been presented. The Froude-Krylov force and the hydrostatic restoring force are calculated over the instantaneous wetted surface of the ship while the forces due to the radiation and scattering potentials over the mean wetted surface. The time-domain radiation and scattering potentials have been obtained from a time invariant kernel of integral equations for the potentials which are discretized according to the second-order boundary element method (Hong and Hong 2008). The diffraction impulse-response functions of the Wigley seakeeping model advancing in transient head waves at various Froude numbers have been presented. A simulation of coupled heave-pitch motion of a long rectangular barge advancing in regular head waves of large amplitude has been carried out. Comparisons between the linear and the approximate body nonlinear numerical results of motions and wave loads of the barge at a nonzero Froude number have been made.
황성철(Sung-Chul Hwang),이병혁(Byung-Hyuk Lee),박종천(Jong-Chun Park),성홍근(Hong-Gun Sung) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.5
The Floating storage and re-gasification unit (FSRU), which has large cargo storage tanks, is a floating liquefied natural gas (LNG) import terminal. The sloshing motion in tanks that are partially filled with LNG can cause impact pressure on the containment system and affect the global motion of the FSRU. Therefore, the accurate prediction of sloshing motion has been a significant issue in the offshore gas production industry. In this paper, a particle method based on the moving particle semi-implicit (MPS) method proposed by Koshizuka and Oka (1996) has been modified to predict sloshing motion accurately in a rectangular tank with the filling ratio of water. The simulation results, including the violent sloshing of the fluid, were validated by comparison with the original MPS method.
길상인(Sang In Keel),윤진한(Jin Han Yun),김석준(Seock Joon Kim),김우현(Woo Hyun Kim),이정규(Lee Jung Kyu),강창구(Chang Gu Kang),성홍근(Hong Gun Sung),정노택(Rho-Taek Jung) 한국해양환경·에너지학회 2004 한국해양환경공학회 학술대회논문집 Vol.2004 No.-
Marine debris incineration system was designed for the thermal treatment of contaminated wastes excepted in the recycle or resources. The design of this system was focused on the perfect gas cleaning including dioxin removal and the strengthening of furnace structure for the foundation on the barge mounted plate. Excellent performance data and the dioxin value of 0.06ng-TEQ/S㎥ mean that the improvement of ocean environment can expected. And also this system can play an important role in the problems of island's municipal waste treatment.
길상인(Sang-In Keel),윤진한(Jin Han Yun),성홍근(Hong Gun Sung),전태병(Tae Byung Chun),정노택(Rho-Taek Jung),김선동(Seon Dong Kim),강창구(Chang Gu Kang) 한국해양환경·에너지학회 2005 한국해양환경공학회 학술대회논문집 Vol.2005 No.11
Considering the durability of FRP(Fiber Reinforced Plastic) vessels and the reduction of fishing boats in great quantities, development of waste FRP vessel treatment technique must be settled without a moment's delay. This experimental research is focused on the establishment of a basic design technique for the composition of a practical system. In the developed waste FRP vessel treatment system, the pre-treatment process composed of cutting and multi-step crushing, and melting process, which uses the heat energy of epoxy resin, were adopted in order to stabilize the glass fiber component. The resulting byproduct of direct melting is generally known as slag, which may be utilized as construction material such as brick, block, etc. Through the experimental setup and high temperature melting tests, this direct melting method is proved to be an environmental and economical method for the practical usage.
선수파 중 슬로싱을 고려한 병렬배치된 두 부유체의 거동 특성에 관한 실험 연구
조석규(Seok-Kyu Cho),성홍근(Hong-Gun Sung),홍장표(Jang-Pyo Hong),홍사영(Sa-Young Hong),홍석원(Seok-Won Hong) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.6
The motions and drift forces of side-by-side moored FSRU and LNGC including the sloshing effect, were studied using experiments. The FSRU and LNGC contained LNG cargo tanks and the LNG sloshing could effect the motions and drift forces of the structures due to its coupling with floating body motion. The effect of coupling can vary with the LNG filling level, and the effect of the filling level was investigated. The coupling effect was stronger at lower filling level. It was confirmed that longitudinal sloshing influenced the surge and surge mean drift force in head sea. In addition, gap flow affected the sway and mean drift forces. Sloshing attenuated the sway and yaw excited by gap flow in side-by-side configuration.