• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.33-33
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• 2018

• Bulletin of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.36-39
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• 1995

본고에서는 고속선의 항행 안전성과 관련된 공통의 문제로서 파랑중 조종성능에 관해서 언급하 고자 한다. 파랑중 조종성능이 문제시되는 것은 선박이 추파(following seas) 또는 추사 파(quartering seas)를 받으면서 고속으로 항해할 때이다. 보통의 속도 범위에서 운항되는 일반 선박중에서도 컨테이너선, 어선 등과 같이 비교적 속력이 빠른 선박은 추사파중에서 선수 동 요가 크게 일어나며, 보침을 위한 조타량이 커짐과 동시에 힁동요가 심하게 일어나는 것으로 알려져 있다. 이러한 불안정 현상은 정도의 차이는 있을지언정 고속선에서도 마찬가지 경향을 보이고 있다. 파랑중 조종성능을 요약하면 추파 또는 추사파중에서의 복원성과 보침성 문제에 귀착된다, 추사파중에서의 복원성 문제는 선체 중심이 파정에 위치할 때 복원력 저하로써 설명될 수 있으며, 이러한 현상은 파장과 선체 길이가 거의 같고 선속이 파속과 거의 같은 조건하에서 일어난다고 알려져 있다. 이러한 조건을 만족하는 선속은 Froude수 0.4 정도로서 고속선의 운항 범위에 미달되는 속도이다. 추사파중에서의 보침성 문제는 브로칭(broaching-to) 현상으로써 설명될 수 있으며, 브로칭 현상은 파장이 선체 길이의 2배 정도이고, 선속과 파속이 거의 같은 조건하에서 일어난다고 알려져 있다. 이러한 조건을 만족하는 선속은 Froude수 0.56 정도로서 고속선의 운항 범위와 일치하는 속도이다. 따라서 본고에서는 고속선을 대상으로 하기 때문에 복원성 문제는 다루지 아니하고 브로칭 현상에 관해서만 간략히 기술하기로 한다.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.42-57
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• 1995

An efficient and accurate scheme has been constructed by taking advantages of the hi-quadratic spline scheme and the higher-order boundary element method selectively depending on computation domains. Boundary surfaces are represented by 8-node boundary elements to describe curved surfaces of a ship and its neighboring free surface more accurately. The variation of the velocity potential complies with the characteristics of the 8-node element on the body surface. But on the free surface, it is assumed to follow that of the hi-quadratic spline scheme. By which, the free surface solution is free from numerical damping and has better numerical dispersion property. As numerical examples, steady and unsteady Neumann-Kelvin problems are considered. Numerical results for a submerged spheroid, Series 60($C_B=0.6$) and a modified support the proposed method. Finally, a new upstream radiation condition is derived using a wave equation operator in order to deal with problems for subcritical reduced frequency. The relevance of this operator has been confirmed in the case of unsteady Kelvin source potential.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.955-964
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• 2022

According to the statistics of maritime accidents statistics that have occurred in Korea over the past five years, maritime accidents caused by fishing boats have increased every year from 1,646 in 2016 to 2,100 in 2020. In particular, of the 378 capsizing accidents that have occurred in the past five years, 252 capsizing accidents of fishing boats account for a high proportion of 66.7%, therefore, it is urgent to come up with countermeasures. In this study, to determine the cause of the capsizing accident of fishing boat No. 66 poongsung, data such as stability and seawater inflow routes were collected, and the effects of waterproof, additional wood decks, and windbreakers on stability on were quantitatively analyzed. Additional decks, windbreakers, and waterproof installed in No. 66 poongsung cause initial list, deteriorate stability, and fail to meet fishing boat structural standards. In addition, it was analyzed that the stability was weakened due to the characteristics of the hull shape of No. 66 poongsung. To estimate the stability at the time of the accident, the stability at the time of the working in the fishing ground condition, amount of seawater inflow according to the change in sea conditions, hull oscillation situation, and change in stability due to the hull factor were calculated. As a result, the minimum GoM was satisfied at the time of working in the fishing ground, but it could not be restored at the maximum wave height of 4 m, and the minimum GoM was not satisfied at the maximum wave height of 4 m owing to the influence of seawater inflow and oscillation due to the hull list. However, the minimum GoM was satisfied if additional decks and windbreakers installation was excluded among the factors affecting the stability of No. 66 poongsung.