• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.791-799
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• 2022

Among excursion and ferry boats, small boats with a length of less than 12 m are exempted from the stability standard according to the ship safety act. The boarding capacity of these small excursion and ferry boats is calculated by the seating area according to the excursion ship and ferry business act. Many excursion and ferry boats have installed deck structures such as awnings after launching. Therefore, this study attempted to analyze the cause of the accident by estimating the stability based on the case of an actual ferry boat capsizing accident. The analysis results indicated that passengers stood up to disembark at the same time while the boarding capacity was exceeded. However, even if the ferry boat complied with the boarding capacity, a possibility of capsize existed if the passengers on one side of the boat stood up. Therefore, the following were suggested to improve the safety: calculating the boarding capacity using the stability test and recommending the maximum total weight for the boarding capacity.

• Journal of Navigation and Port Research
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• v.47 no.6
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• pp.376-385
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• 2023

Fishing boat capsizing accidents account for more than half of all capsize accidents. These can occur for a variety of reasons, including inexperienced operation, bad weather, and poor maintenance. Due to the size and influence of the industry, technological complexity, and regional diversity, fishing ships are relatively under-researched compared to commercial ships. This study aimed to predict the rolling motion time series of fishing boats using an image-based deep learning model. Image-based deep learning can achieve high performance by learning various patterns in a time series. Three image-based deep learning models were used for this purpose: Xception, ResNet50, and CRNN. Xception and ResNet50 are composed of 177 and 184 layers, respectively, while CRNN is composed of 22 relatively thin layers. The experimental results showed that the Xception deep learning model recorded the lowest Symmetric mean absolute percentage error(sMAPE) of 0.04291 and Root Mean Squared Error(RMSE) of 0.0198. ResNet50 and CRNN recorded an RMSE of 0.0217 and 0.022, respectively. This confirms that the models with relatively deeper layers had higher accuracy.

• Journal of the Korean Institute of Navigation
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• v.11 no.2
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• pp.61-72
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• 1987

When a ship is running in following seas, the encounter frequency is reduced to a very low one. In that case broaching, surfiding and capsizing phenomena are most likely to occur due to wave exciting forces acting on a ship in following seas. In this paper, the emphasis is mainly laid upon transverse stability of ships following seas, which is related to capszing phenomenon. The authors take the case that ship speed is equal to the wave celerity, i.e., the encounter frequency is zero. Hydrostatic force and moment due to Froude-Krylov hypothesis are calculated by line intergral method. Transverse stability is evaluated from hydrostatic force and moment. Through the application of present calculation method to box-shaped vessel, it is confirmed that the transversestability of a vessel can be reduced to critical level at wave crest.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.2
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• pp.45-55
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• 1999

The majority of fishing vessels(under 20 tonnages) in Korea have a high casualty accident of the flood and capsizing occurred by lack of stability. Actually, it is so difficult to make out the data of inclining and stability tests of small fishing vessels after building, because most of them were built on experiences of manufacturer. According to above reasons, the aim of this study is an attempt to propose a stability criteria of small fishing vessels as follows: Firstly, it is examined that the stability is driven from a transverse metacenter height of actual ships, which is able to obtain a basic drawing and stability data. Secondly, it is examined the heeling at high-speed turning, and the period of rolling according to B/D(breadth/depth). Finally, it is suggested the stability criteria by using a dynamic state which is applied in passenger boat and fishing vessels over 24 meters.

• Journal of the Korean Professional Engineers Association
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• v.41 no.5
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• pp.41-44
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• 2008

Ships on the sea are exposed to the danger such as collision, stranding, sinking, capsizing and disaster and so on. So, we discuss the factors and the countermeasures for prevention a lot of marine casualty caused on the ship navigation. It is necessary to construct of cooperation system among all organizations relating to salvage on the sea. In order to prevent the marine casualty. it is important to reinforce the crew with safety education and to improve on navigation aids for ships in fairway.

• Bulletin of the Society of Naval Architects of Korea
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• v.22 no.2
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• pp.1-11
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• 1985

Generally, the non-uniform flow with varying speed distribution ca be formed near narrow straits or waterways. One of the most dynamic modes of capsizing can occur as a result of manoeuvring of ships in non-uniform flow. This paper covers the investigation into the factors affecting the likelihood of server ship motions in non-uniform flow. Digital simulation of manoeuvring is carried out in order to predict conditions which could lead to serve ship motions in non-uniform flows. Hydrodynamic force derivatives of a container ship are used. Finally, possible conditions of severe ship motions are suggested and guidelines for reducing the liability to capsize are given both for the ship operator and the naval architect.

• Ocean Systems Engineering
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• v.1 no.3
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• pp.249-261
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• 2011

The stochastic nonlinear dynamic behavior and probability density function of ship rolling are studied using the nonlinear dynamical systems approach and probability theory. The probability density function of the rolling response is evaluated through solving the Fokker Planck Equation using the path integral method based on a Gauss-Legendre interpolation scheme. The time-dependent probability of ship rolling restricted to within the safe domain is provided and capsizing is investigated from the probability point of view. The random differential equation of ships' rolling motion is established considering the nonlinear damping, nonlinear restoring moment, white noise and colored noise wave excitation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.1
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• pp.15-21
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• 2013

The safety and stability of 5MW class offshore wind turbine Jack-up platform was investigated through ocean basin experiment. For simulating the environmental condition of yellow sea in the South Korea, diverse waves, winds and currents were performed based on Froude's number. Regular wave and irregular wave based on Froude's number were applied to the wind turbine structure. In experiments, the height and period of regular wave type were scaled down as the 1:50 ratio of real wave condition. Irregular wave type was simulated with TMA(Texel Storm, Marsen and Arsloe)spectrum. The vertical reaction force, resonance period and wave pressure applied to multi-supporters of wind offshore structure were measured experimentally. Finally, the results showed that the capsizing situation of the offshore structure was generated by the severe environmental condition.

• Selected Papers of The Society of Naval Architects of Korea
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• v.1 no.1
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• pp.37-44
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• 1993

Deck wetness phenomenon has long been considered as one of the factors that degrade the performance of a ship In waves. In rough weather, the frequent skipping of water may give rise to the capsizing of the ship. Therefore an appropriate above water bow shape design is an important asset to a ship of which successful performance in rough weather is a prerequisite such as a warship. In this paper an experimental technique for estimation of deck-wetness frequency is presented. The results of the model tests are compared with those of computations using Ochi's formula. Finally the applicability of Ochi's formula is discussed.

• Journal of Hydrospace Technology
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• v.1 no.1
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• pp.57-65
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• 1995

For the mechanism of ship capsizing, we can generally consider that it\`s caused due to pure loss of stability, parametric oscillation(low cycle resonance) of ship in waves and the broaching phenomena. Among them, low cycle resonance occurs due to the dynamic change of righting arm with respect to the relative position of ship to waves. The dynamic change depends on the encounter period of a ship in following waves. This paper discusses the following items : (1) An analytical expression of GZ curve varying with respect to the relative position of ship to waves, (2) Non-linear equation of motion describing low cycle resonance, (3) The effects of righting arm, stability range and encounter period on low cycle resonance.