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공기챔버 위치에 따른 폰툰형 초대형 구조물 유탄성응답 해석
홍사영(SA-YOUNG HONG),경조현(JO-HYUN KYOUNG),김병완(BYOUNG-WAN KIM) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.1
A numerical investigation ts made on the effects of the location and shape of the front wall of an OWC (Oscillating Water Column) chamber on the hydroelastic response of a VLFS. Most of the studies on the effects of an OWC chamber on the response of a VLFS have assumed the location of the OWC chamber to be at the front of the VLFS. In the present study, an OWC-chamber is introduced at an arbitrary position in relation to a VLFS to determine the influence of the location and shape of the OWC chamber on the hydroelastic response of the VLFS. A finite element method is adopted as a numerical scheme for the fluid domain. or the finite element method, combined with a mode superposition method, is applied in order to consider the change of mass and stiffness The OWC chamber in a piecewise constant manner or the facilitated anefficient analysis of The hydroelastic response of the VLFS, as well as the easy modeling of different shape and material properties for the structure. Reduction of hydroelastic response of the VLFS is investigated for various locations and front wall shapes of the OWC chamber.
홍사영(Hong, Sa-Young),경조현(Kyoung, Jo-Hyun),조석규(Cho, Seok-Kyu),김병완(Kim, Byoung-Wan) 한국소음진동공학회 2007 한국소음진동공학회 논문집 Vol.17 No.1
In this paper, the modified direct method employing beam transformation technique is proposed in order to efficiently calculate hydroelastic responses of floating structure. Since the proposed method expresses the displacements of three-dimensional structure with those of transformed beam which leads to small number of equations of motion, the method is numerically efficient compared to the conventional direct method. To verify the efficiency of the proposed method, a 500 m-long floating structure under wave loads is considered in numerical example. Displacements, bending moments, torsion moments and shear forces are calculated and computing time is examined. The results are also compared with those of the conventional direct method.
초대형 부유식 해상구조물의 유탄성 응답 저감을 위한 진동수주형 방파제 적용
홍사영(Sa Young Hong),경조현(Jo Hyun Kyoung) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
A numerical analysis is made to investigate the hydroelastic response of pontoon-type VLFS with OWC-type breakwater. A OWC(Oscillating Water Column)-type breakwater which is installed in the middle of the VLFS is considered to reduce the hydroelastic response. To analyze the coupled hydroelastic response of VLFS with OWC-type breakwater the mathematical formulation is made in the scope of the classical potential theory. Localized finite element method based on the classical variational principle is adopted as numerical scheme for fluid domain. To analyze the elastic motion of VLFS the mode-superposition method is adopted. The coupled hydroelastic response of VLFS is investigated for the combinations of main parameters of OWC-type breakwater such as location and shape of OWC chamber, bending rigidity variation of VLFS and OWC chamber.
홍사영(Sa Young Hong),김병완(Byoung Wan Kim) 한국해양환경·에너지학회 2021 한국해양환경·에너지학회 학술대회논문집 Vol.2021 No.10
기후온난화의 지구적 어젠다는 다양한 리소스의 신재생 에너지 개발 및 이용에 강력한 추동력을 주고 있다. 그 중에서 바람과 태양광을 이용한 시도가 주를 이루고 있다. 그런데, 풍력발전은 소음문제, 태양광발전은 빛의 반사 및 산림의 훼손으로 인한 환경피해로 인해 해양으로의 진출로 방향이 바뀌고 있으며 자원의 대규모 이용 및 리소스의 고품질 등의 긍정적인 요소가 대규모 해상 신재생 에너지 개발을 부추기고 있다. 전통적인 부유식 해양구조물의 형태인 스파플랫폼이나 반잠수식 시추선 형태의 구조물을 기반구조물로 하는 해상풍력발전에 비해 저수지 등의 내수면 태양광 발전단지를 해상으로 확장하는 문제는 기술적으로 리스크가 상대적으로 많다고 볼 수 있다. 더욱이 태양광발전에 있어 정부의 조급하고 과도한 신재생 에너지 추진 정책과 내수면에서의 일천한 경험이 공학적으로 명백한 위험요소에 대한 의도적 회피와 무지로 인한 문제점 해결의 핵심을 놓칠 수 있다는 우려가 있다. 또한 최근의 언론의 보도를 보면 우리나라의 대규모 태양광 발전단지 후보지가 철새 도래지에 인접하여 새똥으로 인한 예상치 못한 운영상의 어려움이 수면에 떠오르고 있다. 본 연구에서는 그동안 내수면 이용을 대상으로 하여 고려되지 않았던 해상에서의 부유식 수상태양광 구조물의 공학적 핵심 요소에 대해 살펴보고 이에 대한 해결 방안을 논의하고자 한다. 이를 위해서는 MW급 구조물의 특징을 반영한 유탄성 해석 기반의 설계 및 해석, 해상파로 인한 여러 가지 추가적인 고려사항 등을 살펴볼 것이다. 마지막으로 MW 규모의 부유식 태양광 구조물에 대한 설계/해석 예를 보일 것이다. The global agenda of climate warming is giving a strong impetus to the development and use of renewable energy from various resources. Among them, attempts using wind and sunlight are predominant. However, wind and solar power generations are changing their direction to enter the ocean due to environmental damage caused by wind turbine induced noise, reflection of light and damage to forests, while wind and solar energy has positive factors such as large-scale use of resources and high quality of resources. It promotes the development of ocean renewable energy. Compared to offshore wind power generation using traditional floating offshore structures such as spa platforms or semi-submersible rig-type structures, the problem of expanding inland floating solar power generation complexes to the sea has rather a technically high risk. Moreover, there is concern that the government"s hasty and excessive renewable energy promotion policy in solar power generation in GW scale, and its meager experience in inland waters may miss the key to solving problems due to intentional avoidance and ignorance of obvious engineering risk factors at the sea. In addition, according to recent media reports, as the candidate sites for large-scale solar power generation complexes in Korea are adjacent to migratory bird habitats, unexpected operational difficulties due to bird droppings are rising to the surface. In this study, we intend to examine the engineering key elements of floating solar power structures in the sea, which had not been considered for the use of inland waters, and discuss solutions. To this end, we will examine the design and analysis based on the hydroelastic analysis that reflects the characteristics of MW-class structures, and various additional considerations due to sea waves. Finally an example of integrated design and analysis practice of a MW scale photovoltaic power generation plant structure.
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.
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.