• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.4
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• pp.449-456
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• 2015

In this paper, attaching various damping plates to the cylindrical structure and performing numerical simulations try to study heave RAO and natural period for cylinder. Most of all, we identified heave RAO of the cylinder by simulations of the motion and the wave. And then, we performed numerical simulations by changing the size and shape of heave damping plate attached to the cylinder and reviewed the heave RAO and natural period for each case. The conclusions of this research are as follows. Firstly, the natural period of cylindrical structure is increased by attached to the cylinder with heave damping plate and the heave RAO of cylindrical structure is reduced in the peak period for incident wave by attached to the cylinder with from the size of 1.30D for heave damping plate. Secondly, circular plate has long natural period than Y-type plate in all of these sections. Finally, the motion response spectrum considering the marine environment of Piranema field was identified as the heave motion of cylindrical structure is remarkably reduced with both circular plate and Y-type plate in the peak period for incident wave.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.447-452
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• 2010

A very good seakeeping vessel is able to operate effectively even in high sea states and also the passengers and the cargos are ensured in good conditions. The motions of a high speed boats are highly influenced by speed and dynamic forces even in encounter frequencies so that the assessment of seakeeping ability of the design craft in an early stage needs to be calculated for all three motions and for all ralative wave headings. In this paper, it concludes that RAO and RMS values of the catamaran's 3 motion are calculated according as the variation of Beafort scales and ship's speed. The ship motion response of the catamaran based on the RAO and RMS by encounter angles and speed was calculated.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.953-961
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• 2013

In this study, the analyzed turbine is a 5MW upwind-type wind turbine. This conceptual model was made to compare the results of the numerical analysis program in the IEA Annex23 Subtask2 OC3 project. The numerical analysis program used in this study is FAST developed by NREL and AQWA of ANSYS. Motion characteristics, such as RAO, average motion, significant motion and average amplitude of 1/10 highest motion were obtained through the numerical analysis. The results of the numerical analysis were compared with the results of other numerical analyses and the experimental results, and all the results agreed with one another. The results will help resolve the fundamental design trade-offs between basic floating system concepts.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.41-42
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• 2018

This study is about the prediction of ship's roll motion characteristic which has been used for evaluating ship's seakeeping performance. In order to obtain the ship's roll RAO during voyage, this paper utilized machine learning-based surrogate model. By comparing the prediction result data of surrogate model with test data, we suggest the best approximation technique and data sampling interval of the surrogate model appropriate for predicting the ships' roll motion characteristic.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.956-964
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• 2017

This study contributes to deepening understand of the characteristics of fishing vessel rolling motions to improve the development of capsizing alarm systems. A time domain rolling motion simulation was performed. In order to verify capsizing alarm systems, it is necessary to carry out experiments assuming a capsizing situation and perform actual fishing vessel measurements, but these tasks are impossible due to the danger of such a situation. However, in many capsizing accidents, a close connection with rolling motion was found. Accordingly, the rolling motion of a fishing boat, which is the core of a fishing vessel capsizing alarm system, has been accurately measured and a time domain based on a rolling motion simulation has been performed. This information was used to verify the algorithm for a capsizing alarm system. Firstly, the characteristics of rolling motion were measured through a motion experiment. For small vessels such as fishing vessels, it was difficult to interpret viscosity due to analytical methods including CFD and potential codes. Therefore, an experiment was carried out focusing on rolling motion and a rolling mode RAO was derived.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.4
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• pp.397-402
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• 2013

In this study, numerical hull form development of a platform supply vessel, a full scale with the overall length of 26.75m, was performed to predict a bare-hull resistance and a large scale of model tests with a 1/10 scaled model were conducted to verify the success of numerical results. Numerical analysis on heave and pitch motion as a function of encounter frequency and ship's speed for the prediction of seakeeping characteristics are also presented. The experiment results of resistance agreed well with numerical analysis. As a result in the motion response characteristics, the heave RAO indicates high values with the range of encounter frequency 1.8~2.0. The Pitch RAO indicates high motion response characteristics at Beaufort scale No. 3 and 4 in rough seas.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.122-124
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• 2013

최근 쌍동형 선박의 운동성능이 우수함에 따라 대형화가 이루어지고 있으며, 이에 따른 다양한 해상상태 변화에 따른 운동성능의 평가를 요구하고 있다. 쌍동형 선박의 경우 횡동요에서 매우 우수한 운동성능을 나타내고 있으나 선박규모의 대형화에 따른 운동성능의 추가적인 계산이 필요하다. 본 연구에서는 60피트급 쌍동형 선박의 종운동성능을 선속과 파랑조건에 따라 추정 및 성능검토를 수행하고자 한다. 선수 및 선미 형상변화가 종운동성능에 미치는 영향을 알아보기 위하여 Pitch 운동성능을 추정하였으며 그 결과를 분석하고자 한다. 이를 위해 사례선을 적용하고 이를 기반으로 성능검토를 수행하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.5-7
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• 2011

LNG 운반선이 대형화 됨에 따라 슬로싱의 동적거동에 대한 영향에 대한 관심이 증가하고 있다. 본 연구에서는 시간영역에서 슬로싱 현상과 FPSO와 LNG운반선의 거동을 동적으로 연성하여, LNG 슬로싱이 두 부유체의 global performance에 미치는 영향을 시간영역에서 시뮬레이션하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.236-237
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• 2017

In this research, experimental seakeeping results of Warped hull form 2 on the regular waves were compared with numerical results of strip method and CFD. In case of ship's speed, there are 3 cases (3.4m/s, 4.6m/s, 5.75m/s) for numerical simulation, and they are belong to semi-planing and planing condition. Consequently, in case of strip method, it is shown that the resonance phenomena occurred from around ${\lambda}/L_{OA}=2$ to 4 and RAO value were significantly higher than that of other. this is different from experimental results. In case of CFD, overall trends were similar with experimental values except there are somewhat excessive RAO values around ${\lambda}/L_{OA}=0.5$ to 2.5. these phenomena is confirmed that it became larger as the ship's speed increased, and it was considered that the error occurred because the number of mesh in vertical direction of wave height at ${\lambda}/L_{OA}=0.5$ to 2.5 were relatively less than those of wave height at ${\lambda}/L_{OA}=2.5$ to 5.2.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.6
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• pp.485-491
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• 2017

An experimental study on the reduction of vertical motion of floating body using floating-submerged body interaction was performed in a two-dimensional wave channel. The system consisting of a floating and submerged body that only move vertically was modeled. This experiment was designed based on the results of theoretical analysis of two-body interaction. The results showed a tendency to significant reduction of heave RAO of floating body due to submerged body. Various connection line stiffness and dimension of the submerged body were applied to investigate the effect of two-body interaction on the vertical motion of the bodies, Heave RAOs of the floating-submerged body were compared with those of single body. From the comparison study, we obtained an optimum condition of connection line and dimension of submerged body for maximum heave reduction at the resonant period of single body.