• 한국해양공학회지
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• 제20권2호
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• pp.36-40
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• 2006

As large waves enter a harbor, during their propagation, the motions a floating body are large and if may even be damaged by waves. This phenomenon may be caused by harbor resonance, resulting from large motion at low wave frequency, which is close to the natural frequency of a vessel. In order to calculate the motion of a floating body in a harbor, it is necessary to use the wave forces containing the body-harbor interference. The simulation program to predict the motions of a floating body by waves in a harbor is developed, and this program is based on the method of velocity potential contiuation method proposed by Ijima and Yoshida The calculated results are shown by the variation of wave frequency, wave angle, and the position of a floating body.

• 한국항해항만학회지
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• 제36권1호
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• pp.27-34
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• 2012

레저용 플로팅 건축물은 구조물 안전성, 건축물 용도, 건설 및 관리 경제성, 주변 지역이나 도시와 개발 연계성, 해양환경에의 영향 등을 고려할 때 입지선정에 대한 체계적 지침과 합리적 기준이 반드시 필요하다. 그러나 현재 우리나라에는 레저용 플로팅 건축물이 많이 계획되고 설치되는 시점에 있음에도 불구하고 입지선정에 관한 연구나 지침이 전혀 없는 실정이다. 따라서 본 연구는 레저용 플로팅 건축물의 입지선정을 위해 체계적 입지선정프로세스. 합리적 입지선정기준 및 입지평가지침을 제시하는 것이 목적이다. 본 연구에서는 지자체나 민간 기업에서 레저용 플로팅 건축물을 계획할 경우 체계적이고 합리적 입지선정에 활용할 수 있도록 입지선정과정, 입지선정기준, 입지평가항목 및 요인을 그림과 표로 알기 쉽게 제시하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권2호
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• pp.206-218
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• 2014

The wave attenuation by floating breakwaters in high amplitude waves, which can lead to wave overtopping and breaking, is examined by numerical simulations. The governing equations, the Navier-Stokes equations and the continuity equation, are calculated in a fixed Cartesian grid system. The body boundaries are defined by the line segment connecting the points where the grid line and body surface meet. No-slip and divergence free conditions are satisfied at the body boundary cell. The nonlinear waves near the moving body is defined using the modified marker-density method. To verify the present numerical method, vortex induced vibration on an elastically mounted cylinder and free roll decay are numerically simulated and the results are compared with those reported in the literature. Using the present numerical method, the wave attenuations by three kinds of floating breakwaters are simulated numerically in a regular wave to compare the performance.

• Journal of Multimedia Information System
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• 제7권4호
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• pp.269-276
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• 2020

The small craft including jet-board for leisure are commonly smaller than the general commercial vessels. For the floating vessel, the motion analysis is significantly important component to design the shape. It is, however, hardly predicting its behavior by using conventional boundary element method due to violating small amplitude assumption for potential theory. The computational fluid dynamics method can afford to simulate such small craft, but its grid system was not able to calculate motion, because movable body disturbs the grid system by confliction. The dynamics fluid body interaction model with over-set mesh system can be dealt with movable floating body under irregular ocean wave. In this study, several cases were considered to reveal that DFBI is essential method to predict floating body motion. The single phase simulate was conducted to establish the shape perfection, and then the validated vessel was simulated with ocean waves weather DFBI option on or off. Through the comparison, the results between the cases of DFBI on and off shows significantly difference. It was claimed that the DFBI was necessary not only to calculation body motion, but also to predict accurate drag and lift force on the floating body for small size craft.

• 대한조선학회논문집
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• 제46권5호
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• pp.527-535
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• 2009

This paper describes the control system to suppress the load pendulation using tagline for the floating crane. Dynamic equation of motion of the floating crane and the load is derived using Newton's 2nd law and free body model. The floating crane and the load are assumed that they move in center plane. Each rigid body has 3 DOF (surge, heave, pitch), because it moves in two directions and rotates. Then, this system, which is composed of two rigid bodies, has 6 DOF. The gravitational force, the hydrostatic force, the hydrodynamic force and the tension of the wire rope are considered as external forces, which affect to the floating crane. To suppress the pendulation of the load, the tagline, which connects between the load and the float crane, is applied to the system. The tagline is composed of the spring and the wire rope. Proportional and Derivative control is used as a linear control algorithm. The results of the numerical analysis of the 3,600 ton floating crane show that the tagline system is effective to suppress the load pendulation.

• 대한기계학회논문집A
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• 제36권6호
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• pp.681-689
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• 2012

본 연구에서는 병렬 연결된 해상 크레인을 이용하여 5,000ton 이상의 기가 블록급 대형 중량물을 인양할 때 해상 크레인과 대형 중량물 사이에 연결된 와이어 로프에 작용하는 장력을 계산하기 위해 다물체계 동역학 시뮬레이션을 수행하였다. 이를 위해, 해상 크레인, 바지선, 대형 중량물은 각각 6 자유도 운동을 하고, 이들 사이에는 서로간의 구속에 의한 연성을 가지도록 모델링 하였다. 또한 해상 크레인 및 바지선에 작용하는 외력으로 유체 정역학 힘과 유체 동역학 힘을 고려하였고, 각각의 물체에 독립적으로 작용한다고 가정하였다. 본 시뮬레이션 결과, 향후 해상크레인을 병렬 연결하여 대형 중량물을 인양하는 공법의 안정성을 확인하고 공학적인 지침을 마련할 수 있는 근간이 될 수 있으리라 예상한다.

• 한국항해항만학회지
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• 제35권5호
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• pp.401-406
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• 2011

경제적 여유와 함께 사람들의 요구가 다양화 되면서 해양 레저에 대한 관심이 증가하고 있다. 삼면이 바다인 우리나라는 바다를 이용한 해양 레저의 잠재력이 매우 높기 때문에 해양 리조트 개발이 증가할 것으로 예상된다. 그러나 이미 포화상태에 이르렀으며 또한 환경문제를 내포하고 있는 매립에 의한 개발은 상당한 어려움이 따를 것으로 예상된다. 이에 대한 대안으로 플로팅 건축에 의한 개발이 확대될 것으로 기대되지만 플로팅에 의한 해상호텔에 대한 연구는 아직 초보적인 단계에 있으며 이용객의 쾌적성에 직접적인 영향을 미치는 공조 설비 용량을 선정하기 위한 부하계산에 대한 연구는 전무하다고 할 수 있다. 본 연구에서는 육상의 일반적인 호텔과 선박의 공조부하 계산법을 비교 분석함으로써 해상호텔의 공조부하계산방법에 대해 검토한다.

• 한국해양공학회지
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• 제34권6호
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• pp.394-405
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• 2020

To assess the station-keeping performance of floating structures in the Arctic region, the ice load should be considered along with other environmental loads induced by waves, wind, and currents. However, present methods for performance evaluation in the time domain are not effective in terms of time and cost. An ice load generation module is proposed based on the experimental data measured at the KRISO ice model basin. The developed module was applied to a time domain simulation. Using the results of a captive model test conducted in multiple directions, the statistical characteristics of ice loads were analyzed and processed so that an ice load corresponding to an arbitrary angle of the structure could be generated. The developed module is connected to commercial dynamic analysis software (OrcaFlex) as an external force input. Station-keeping simulation in the time domain was conducted for the same floating structure used in the model test. The mooring system was modeled and included to reflect the designed operation scenario. Simulation results show the effectiveness of the proposed ice generation module and its application to station-keeping performance evaluation. Considering the generated ice load, the designed structure can maintain a heading angle relative to ice up to 4°. Station-keeping performance is enhanced as the heading angle conforms to the drift direction. It is expected that the developed module will be used as a platform to verify station-keeping algorithms for Arctic floating structures with a dynamic positioning system.

• 한국해양공학회지
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• 제5권2호
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• pp.156-156
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• 1991

A numerical procedure is described for predicting the dynamic responses of combined systems of floating breakwaters and huge offshore structures supported by a large numer of the floating bodies in waves. The hydrodynamic interactins among tatal floating bodies are taken into account in their exact form within the context of linear potential theory. Wave control effects are discussed with both hydrodynamic interactions and hydrodynamic-structure interaction effects. The method presented is applicalbe to combined systems of floating breakwaters and huge structures for ocean space utilization for which a number of practical uses are seen in the future.

• International Journal of Ocean System Engineering
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• 제2권3호
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• pp.176-184
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• 2012

Installing floating structures in a coastal area requires careful observation of the finite-depth effect. In this paper, a Rankine panel method that includes the finite-depth effect is developed in the time domain. The bottom boundary condition is satisfied by directly distributing Rankine panels on the bottom surface. A stepwise analysis is performed for the radiation diffraction problems and consequently freely-floating motion responses over different water depths. The hydrodynamic properties of two test hulls, a Series 60 and a floating barge, are compared to the results from another computation program for validation purposes. The results for both hulls change remarkably as the water depth becomes shallower. The important features of the results are addressed and the effects of a finite depth are discussed.