• 한국멀티미디어학회논문지
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• 제10권6호
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• pp.770-778
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• 2007

Fish schooling or group moving in cyber underwater is a part of beautiful and familiar ecosystem. It is not so easy to present the behavior of fish crowd naturally as a computer animation. Thanks to development of computer graphics in entertainment industry, the numbers of digital films and animations is increased and the scenes of numerous crowd are shown to us. Though there are many studies on the techniques to process the behavior of crowd effectively and the developments of crowd behavioral systems, there is not enough study on the development for an efficient crowd behavioral simulator. In this' paper, we smartly present the types offish behavior in cyber underwater and make up for the weak points of time and cost. We develop the fish schooling behavior simulator for the contents of cyber underwater, automating fish behavioral types realistically and efficiently.

• 한국전자통신학회논문지
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• 제1권1호
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• pp.27-35
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• 2006

가상 해저 환경 속에서 군중 행동은 영화, 게임 등의 엔터테인멘트 산업에서 많은 장면으로 연출된다. 컴퓨터 그래픽스 기술의 발달로 인하여 디지털 영화나 애니메이션이 점차 증가함에 따라 다수의 캐릭터들이 등장하는 장면을 쉽게 접할 수 있다. 가상 환경에서 군중의 행동을 효율적으로 처리하는 기술에 관련해서 군중 장면 처리 및 군중 행동 시스템의 구현에 관한 연구는 있었으나, 자연스러운 군중 행동 시뮬레이터를 개발하는 연구는 아직 미흡한 편이다. 본 논문에서는 가상 해저환경에 존재하는 다수의 물고기들의 행동유형을 스마트하게 표현하여 시간과 비용이 많이 소요되는 단점을 보완하며 fish 군중행동 유형을 자동화하면서 사실적이면서 효율적인 가상 해저 환경 콘텐츠 제작을 구현하기 위한 fish 군중행동 시뮬레이터를 개발한다.

• 한국전자통신학회논문지
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• 제2권3호
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• pp.157-162
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• 2007

The goal of researching a proper crowd animation is to design system that is satisfied with the reality of scenes, performance of system, and interaction with users to show the crowd vividly and effectively in virtual underwater world. In this paper, we smartly expressed the behavior patterns for flocks of fish in virtual underwater and we made up for the weak points in spending time and cost to produce crowd animation. We compared with the number of mesh, the number of fish, the number of frame, elapsed time, and resolution and analyzes them with the fish behavior simulating system. We developed a virtual underwater simulator using this system.

• 한국전자통신학회논문지
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• 제2권1호
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• pp.25-33
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• 2007

가상 해저 환경 속에서 군중 행동은 영화, 게임 등의 엔터테인멘트 산업에서 많은 장면으로 연출된다. 컴퓨터 그래픽스 기술의 발달로 인하여 디지털 영화나 애니메이션이 점차 증가함에 따라 다수의 캐릭터들이 등장하는 장면을 쉽게 접할 수 있다. 가상 환경에서 군중의 행동을 효율적으로 처리하는 기술에 관련해서 군중 장면 처리 및 군중 행동 시스템의 구현에 관한 연구는 있었으나, 자연스러운 군중 행동 시뮬레이터를 개발하는 연구는 아직 미흡한 편이다. 본 논문에서는 가상 해저환경에 존재하는 다수의 물고기들의 행동유형을 스마트하게 표현하여 시간과 비용이 많이 소요되는 단점을 보완하며 fish 군중행동 유형을 자동화하면서 사실적이면서 효율적인 가상 해저 환경 콘텐츠 제작을 구현하기 위한 fish 군중행동 시뮬레이터를 개발한다.

• 한국해양공학회지
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• 제19권3호
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• pp.31-38
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• 2005

Ocean developments gradually move to deep-sea in the 21 century. A deep-sea unmanned underwater vehicle is one of important tools for ocean resource survey. A marine cable plays an important role for the safe operation and signal transmission of a deep-sea unmanned underwater vehicle. The umbilical cable of a deep-sea unmanned underwater vehicle is excited by surface vessel motion and shows non-linear dynamic behaviors. A numerical method is necessary for analysing the dynamic behavior of a marine cable. In this study, a numerical program is established based on a finite difference method. The program is appled to 6000m long cable for a deep-sea unmanned underwater vehicle and shows good reasonable results.

• 한국해양공학회지
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• 제32권4호
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• pp.222-227
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• 2018

Most underwater acoustic arrays for low frequency operation are deployed vertically, but a mid-range frequency horizontal array system is being developed by the Korea Research Institute of Ships and Ocean Engineering (KRISO). The horizontal array platform is deployed underwater and kept in place by weather vaning mooring. This is essential because it is nearly impossible to keep a submerged body at a given position in the water without any external force. Hence, the horizontal array platform can maintain the desired position in the presence of a weak tidal current. The objective of this study is to design an underwater platform that can maintain its horizontal position in a weak current. First, the authors investigated various virtual models, selected one of the models, and performed a small model test of the selected model at a basin. We calculated the external forces associated with the 2D motion, and then we conducted a large basin test followed by a circulation water channel test for the manufactured array platform. The results of the simplified 2D motion calculation essentially matched the results of the underwater test.

• Coupled systems mechanics
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• 제7권3호
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• pp.333-351
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• 2018

In the present paper, the behavior of the Karaj double curvature arch dam is studied focusing on the effects of structural nonlinearity on the responses of the dam body when an underwater explosion occurred in the reservoir medium. The explosive sources are located at different distances from the dam and the effects of the cavitation and the initial shock wave of the explosion are considered. Different amount of TNT are considered. Two different linear and nonlinear behavior are assumed in the analysis and the dam body is assumed with and without contraction joints. Radial, tangential and vertical displacements of the dam crest are obtained. Moreover, maximum and minimum principal stress distributions are plotted. Based on the results, the dam body responses are sensitive to the insertion of joints and constitutive model considered for the dam body.

• 한국해양공학회지
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• 제1권2호
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• pp.67-73
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• 1987

The feasibility for a practical use of underwater wet arc welding process is experimentally investigated by using low hydrogen and high oxide type electrodes and TMCP steel plates. Main results are summarized as follows: 1)The absorption speed of the coated low hydrogen and high titanium oxide type eletrodes becomes constant after about 30 minutes in water, and more steeping time in water does not influnce welding arc behavior. 2) By bead appearance and X-ray inspection, the high titanium oxide type electrode is better than the low hydrogen type in underwater arc welding process. 3) The mechanical properties of underwater wet arc welds depend upon welding conditions more than those of in-air welds, and the optimum welding condition can be obtained. 4) Because of quenching effect by rapid cooling rate in underwater wet welding, the maximum hardness of HAZ is increased relatively higher in underwater wet welding, process.

• Journal of Advanced Research in Ocean Engineering
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• 제3권1호
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• pp.25-31
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• 2017

Generally, underwater gliders do not have separate propellers for their forward movement. They derive a propulsive force due to the difference between their buoyancy and gravity. The attitude of an underwater glider is controlled by changing the relative position of the buoyancy center and mass center. In this study, we derived nonlinear 6-DOF dynamic and mathematical models for the motion controller and buoyancy controller. Using these equations, we performed dynamic underwater glider simulations and verified the suitability of the design and dynamic performance of the proposed underwater glider.

• 한국해양공학회지
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• 제32권5호
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• pp.324-332
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• 2018

It is known that damages to the subsea cables used for electric power transmission between islands and countries, including renewable energy from offshore wind power, current, tides, etc., cost much to restore, which causes social and economic losses. Various types of fishing rigs and anchors have been reported to be the greatest hazards to subsea cables. It is possible to design and construct a suitable protection facility for a subsea cable by precisely estimating the underwater behavior of such hazardous apparatuses. In this study, numerical simulations of the underwater behaviors of various hazardous apparatuses were carried out using fluid-structure interaction (FSI) analysis as a basic study to simulate the actual behavior phenomena of hazardous apparatuses in relation to a subsea cable. In addition, the underwater drop characteristics according to the types of hazardous apparatuses were compared. In order to verify the accuracy of the FSI analysis method used in this study, we compared the test results for underwater drops of a steel ball bearing. Stock anchors, stockless anchors, and rocket piles, which were actually reported to be the cases of damage to subsea cables along the southwest coast of Korea, were considered as the hazardous apparatuses for the numerical simulations. Each hazardous apparatus was generated by a Lagrangian model and coupled with the fluid domain idealized by the Eulerian equation to construct the three-dimensional FSI analysis model. The accuracy of the numerical simulation results was verified by comparing them with the analytical solutions, and the underwater drop characteristics according to the types of hazard apparatuses were compared.