• Title/Summary/Keyword: Floating Body

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Impact onto an Ice Floe

  • Khabakhpasheva, Tatyana;Chen, Yang;Korobkin, Alexander;Maki, Kevin
    • Journal of Advanced Research in Ocean Engineering
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    • v.4 no.4
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    • pp.146-162
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    • 2018
  • The unsteady problem of a rigid body impact onto a floating plate is studied. Both the plate and the water are at rest before impact. The plate motion is caused by the impact force transmitted to the plate through an elastic layer with viscous damping on the top of the plate. The hydrodynamic force is calculated by using the second-order model of plate impact by Iafrati and Korobkin (2011). The present study is concerned with the deceleration experienced by a rigid body during its collision with a floating object. The problem is studied also by a fully-nonlinear computational-fluid-dynamics method. The elastic layer is treated with a moving body-fitted grid, the impacting body with an immersed boundary method, and a discrete-element method is used for the contact-force model. The presence of the elastic layer between the impacting bod- ies may lead to multiple bouncing of them, if the bodies are relatively light, before their interaction is settled and they continue to penetrate together into the water. The present study is motivated by ship slamming in icy waters, and by the effect of ice conditions on conventional free-fall lifeboats.

A Study on the Physical Model Establishment of Hydraulic Secondary Conversion Device of Wavestar Type Wave Power Generator (WAVESTAR형 파력발전장치의 유압식 2차변환장치의 물리모델 구축에 관한 연구)

  • Lee, Jung-Hee;Oh, Jaewon;Ha, Yoon-Jin;Park, Ji-Yong;Cheon, Ho-Jeong;Kim, Kyong-Hwan
    • Journal of the Korean Society of Industry Convergence
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    • v.23 no.6_2
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    • pp.999-1006
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    • 2020
  • This study was conducted to develop an efficiency prediction program of a hydraulic secondary energy converter for calculating annual power generation of a Wavestar type wave power generator. Using the period and wave height obtained from the frequency domain analysis, the behavior of the floating body was obtained by assuming the sin function. The piston displacement and speed of the hydraulic cylinder were calculated considering the behavior of the floating body and the shape of the mechanism. The numerical simulation of the hydraulic system was performed by physically modeling the hydraulic cylinders, check valves, hydraulic motors, which are the main devices. In the future, this analysis program will be used to develop a program for estimating annual power generation of a moveable body type wave power generation device.

A study on the conceptual design of oceanographic buoy systems (해양 관측용 부이의 개념 설계 연구)

  • 조규남;이우섭
    • Journal of Ocean Engineering and Technology
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    • v.11 no.4
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    • pp.205-212
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    • 1997
  • The major subject of this paper is the conceptual design of a cable-buoy system based on mechanics of floating bodies and mooring lines. The goal is to present a systematic relevant analysis procedure for the conceptual design of oceanographic buoy systems. The dynamics of a free floating body with an anchoring line is studied and a model is proposed through the primary engineering.

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The Hydrodynamic Interaction Effects between Two Barges on the Motion Responses (상호작용을 고려한 두 바아지의 운동응답)

  • S.P.,Ann;K.P.,Rhee
    • Bulletin of the Society of Naval Architects of Korea
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    • v.24 no.1
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    • pp.29-34
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    • 1987
  • In this paper, a three dimensional singularity distribution method is applied to investigate the hydrodynamic interactions between two barges floating on a free surface of a deep water. The results show that the hydrodynamic interaction forces are important in the calculation responses of two barges floating in each other's vicinity. Furthermore the trends of hydrodynamic forces due to the motion of body itself are different from those of a single barged, and the motions of the seaward barge can sometimes exceed those of the seaward barged.

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NUMERICAL METHOD IN WAVE-BODY INTERACTIONS

  • MOUSAVIZADEGAN S. H.;RAHMAN M.
    • Journal of applied mathematics & informatics
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    • v.17 no.1_2_3
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    • pp.73-91
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    • 2005
  • The application of Green's function in calculation of flow characteristics around submerged and floating bodies due to a regular wave is presented. It is assumed that the fluid is homogeneous, inviscid and incompressible, the flow is irrotational and all body motions are small. Two methods based on the boundary integral equation method (BIEM) are applied to solve associated problems. The first is a low order panel method with triangular flat patches and uniform distribution of velocity potential on each panel. The second method is a high order panel method in which the kernels of the integral equations are modified to make it nonsingular and amenable to solution by the Gaussian quadrature formula. The calculations are performed on a submerged sphere and some floating spheroids of different aspect ratios. The excellent level of agreement with the analytical solutions shows that the second method is more accurate and reliable.

Development of Aerodynamic Analysis Technology for Wind Turbines using a Multibody Dynamic Analysis Software (다물체 동력학 해석 프로그램을 이용한 풍력발전기 공력해석 기술개발)

  • Rim, Chae Whan;Bang, Je Sung;Cho, Huije;Moon, Seok Jun;Chung, Tae Young
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.180.2-180.2
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    • 2010
  • Simulation technology for dynamic analysis of wind turbine is developed. The Aerodyn and the DAFUL are chosen for aerodynamic analysis and multi-body and flexible body dynamics respectively. Subroutines and variables of Aerodyn developed by NREL are analyzed with hub-height wind data, full field turbulent wind data and Airfoil data. The interface to perform coupled analysis between AeroDyn and DAFUL, GUI for modeling several parts of wind turbines are developed. The program will be extended to analyze the coupled analysis of aerodynamic and hydrodynamic behavior for floating offshore wind turbines.

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Numerical Analysis of Hydrodynamic Forces on a Floating Body in Two-layer Fluids (밀도가 상이한 두 유체층에서 부유체 동유체력 특성의 수치적 해석)

  • Kim, Mi-Geun;Koo, Weon-Cheol
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.3
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    • pp.369-376
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    • 2010
  • In this study, a radiation and a diffraction problems of a floating body in two-layer fluids were solved by the Numerical Wave Tank(NWT) technique in the frequency domain. In two-layer fluids, two different wave modes exist and the hydrodynamic coefficients can be obtained separately for each mode. The two-domain Boundary Element Method(BEM) in the potential fluid using the whole-domain matrix scheme was used to investigate the characteristics of wave forces, added mass and damping coefficients. The effects of the ratio of density and water depth in the lower domain were also evaluated and compared with given references.

A Capacitorless 1-Transistor DRAM Device using Strained-Silicon-on-Insulator (sSOI) Substrate (Strained-Silicon-on-Insulator (sSOI) 기판을 이용한 Capacitorless 1-Transistor DRAM 소자)

  • Kim, Min-Soo;Oh, Jun-Seok;Jung, Jong-Wan;Lee, Young-Hie;Chung, Hong-Bay;Cho, Won-Ju
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.95-96
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    • 2009
  • A fully depleted capacitorless 1-transistor dynamic random access memory (FD 1T-DRAM) based on a sSOI strained-silicon-on-insulator) wafer was investigated. The fabricated device showed excellent electrical characteristics of transistor such as low leakage current, low subthreshold swing, large on/off current ratio, and high electron mobility. The FD sSOI 1T-DRAM can be operated as memory device by the floating body effect when the substrate bias of -15 V is applied, and the FD sSOI 1T-DRAM showed large sensing margin and several milli seconds data retention time.

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On the Time-Mean Drift Force Acting on a Floating Offshore Structure in Wave (부유식 해양구조물에 작용하는 시감평균 파표류력에 관한 고찰)

  • 홍도천
    • Journal of Ocean Engineering and Technology
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    • v.16 no.3
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    • pp.8-18
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    • 2002
  • Formulation of the far-field method for the prediction of time-mean hydrodynamic force and moment acting on a 3-D surface-piercing body in waves is reviewed. It is found that the inequality between the weight of the floating body and its buoyancy force permits the replacement of the fluid particles inside the control surface by the fluid particles outside the control surface. Under such circumstances, momentum exchanges across the control surface make the time-mean value of the time rate of the momentum of the fluid inside the control surface non-vanishing. It is a second-order quantity which is hard to calculate by the far-field method. The drift forces and moments on half-immersed ellipsoids are calculated by both the far-field method and the near-field method. The discrepancy between two numerical results is presented and discussed.

A study on Motion Characteristics of VLCO by Draft (Simple floating body) (가변진동수주장치의 흘수변화에 따른 운동특성연구 (단일 부유체))

  • Lee, Seung-Chul;Bae, Sung-Yong
    • Journal of Power System Engineering
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    • v.18 no.5
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    • pp.16-21
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    • 2014
  • The structure of the variable liquid column oscillator(VLCO) is analogous to that of the tuned liquide column damper used to suppress oscillatory motion in large structures like tall buildings and cargo ships. VLCO is the technology to absorb high potential energy made by process of accelerated motions to occur the effect of an air spring by installation of inner air chamber. So, the application of VLCO can obtain to improve efficiency of energy than wave energy converters made in Pelamis Company. In this research, the experiments were carried out for the motion characteristics of simple floating body by varying the amount of internal fluid. The experimental results were compared with the calculated results.