• Ocean Systems Engineering
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• v.9 no.2
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• pp.157-177
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• 2019

Studies on motion response of a vessel is of great interest to researchers, since a long time. But intensive researches on stability of vessel during motion under dynamic conditions are few. A numerical model of vessel is developed and responses are analyzed in head, beam and quartering sea conditions. Variation of response amplitude operator (RAO) of vessel based on Strip Theory for different wave heights is plotted. Validation of results was done experimentally and numerical results was considered to obtain effect of damping on vessel stability. A scale model ratio of 1:125 was used which is suitable for dimensions of wave flume at National Institute of Technology Calicut. Stability chart are developed based on Mathieu's equation of stability. Ince-Strutt chart developed can help to capture variations of stability with damping.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.810-819
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• 2017

The purpose of this study is to evaluate port use and the distribution of risk factors in 15 major ports in Korea, delineating the risk of each port after classifying the ports into four risk groups based on estimated risks. The placement of response vessels is then analyzed accordingly. Based on the results, danger was estimated to be especially high in ports where large-scale petrochemical facilities are located, such as Yeosu Gwangyang ports (1.85), Ulsan port (1.33) and Daesan port (1.25). The ports showing the next highest degree of danger were Pusan (0.95) and Incheon (0.83), which have significant vessel traffic, followed by Mokpo (0.71) and Jeju (0.49), which expanded their port facilities recently and saw an increase in large vessel traffic. Next is Masan (0.44), for which many fishing permits in the vicinity. When the relative ratios of each port were graded based on the Yeosu Gwangyang Ports, which showed the highest risk values, and risk groups were classified into four levels, the highest risk groups were Yeosu Gwangyang, Ulsan, Daesan and Pusan, with Incheon, Mokpo, Jeju, and Masan following. Pyeongtaek Dangjin, Pohang, Gunsan, and Donghae Mukho were in the mid-range danger group, and the low risk groups were Samcheonpo, Okgye, and Changsungpo. Among these, all response vessel placement ports specified by current law were above the mid-range risk groups. However, we can see that ports newly included in mid-range risk group, such as Mokpo, Jeju, and Donghae Mukho, were excluded from the pollution response vessel placement system. Therefore, to prepare for marine pollution accidents these three ports should be designated as additional response vessel placement ports.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.491-500
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• 2020

The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.2
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• pp.64-72
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• 1998

Dynamic response analysis is carried out for slender marine structures such as tensioned risers and tethers of tension leg platform, which are subjected to floating vessel motions as well as environmental forces arising from ocean waves. A mumerical analysis procedure is developed by using finite element model of the structural member. Dynamic analses are performed in the time domain for regular waves. Parameter studies are carried out to highlight the effects of surface vessel motions on the lateral dynamics of the structures. Example results of displacements, bending stresses are compared for various in water depth, environmental condition and vessel motion. Some instability conditions of the structures due to time-varying tension by vessel heave motion are discussed through the example analyses. As the results, the interaction between vessel surge and heave motions amplifies the total structural response of a riser. In the case of a tether, the effect of vessel heave motion during heavy storm is seemed to be quite significant to lateral response of the structure.

• Journal of Navigation and Port Research
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• v.33 no.2
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• pp.111-117
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• 2009

On May 12th, 2007 a merchant vessel of Golden Rose (South Korea) sank into near 38 mile from Yentai in China after the vessel collided with a container vessel of Jinsung (China), leaving all 16 sailors, including seven South Koreans, missing. According to the official report. The Chinese vessel, authorities, and South Korean government did not coordination q rescue and salvage for the sailors and vessel properly as follows: 1) The Chinese vessel left the scene without rescue and salvage of the sailors, 2) Chinese authorities failed to comply with law of the sea that required them to report the collision to South Korea immediately after confirming the accident, and 3) The South Korean government is also being criticized for its slow response to the incident since the government did not set up a response team until 21 hours after the incident. In order to reduce this number of sailor missing in future incidents, this research is studied regarding assembling conferences, assigning SRR in ASEAN+3, simplicity to enter other territory waters and cooperative training and education for the SAR.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.139-139
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• 2017

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.140-140
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• 2017

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.141-141
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• 2017

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.6
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• pp.604-609
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• 2012

Our country has experienced some difficulties with clean up operation of massive marine oil pollution due to the lack of oil spill response equipments. And there was the case that a fishing vessel performed clean up operation had not received any proper payments because of its inefficient oil spill response operation. Thus, it is important to develop an efficient oil recovery equipment for small vessel and adopt it as a part of oil pollution prevention policy. These efforts could prepare oil spill response equipment in advance and use a fishing vessel registered in the affected area by massive marine oil pollution. Therefore, this study examines and adopts a suitable subject vessels as a first step for developing oil recovery system fitting with small vessels for national use.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.367-375
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• 2018

The present paper considers the contact between energy-saving device of ice-class vessel and ice block. The main objective of this study is to clarify the tendency of the ice impact force and the structural response as well as interaction effects of them. The contact analysis is performed by using LS-DYNA finite element code. The main collision scenario is based on Finnish-Swedish ice class rules and a stern duct model is used as an energy-saving device. For the contact force, two modelling approaches are adopted. One is dynamic indentation model of ice block based on the pressure-area curve. The other is numerical material modelling by LS-DYNA. The authors investigated the sensitivity of the structural response against the ice contact pressure, the interaction effect between structure and ice block, and the influence of eccentric collision. The results of these simulations are presented and discussed with respect to structural safety.