• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.4
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• pp.439-450
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• 2023

In this study, the impact load resulting from collision with the fuel rods of surrogate spent nuclear fuel (SNF) assemblies was measured during a rolling test based on an analysis of the data from surrogate SNF-loaded sea transportation tests. Unfortunately, during the sea transportation tests, excessive rolling motion occurred on the ship during the test, causing the assemblies to slip and collide with the canister. Hence, we designed and conducted a separate test to simulate rolling in sea transportation to determine whether such impact loads can occur under normal conditions of SNF transport, with the test conditions for the fuel assembly to slide within the basket experimentally determined. Rolling tests were conducted while varying the rolling angle and frequency to determine the angles and frequencies at which the assemblies experienced slippage. The test results show that slippage of SNF assemblies can occur at angles of approximately 14° or greater because of rolling motion, which can generate impact loads. However, this result exceeds the conditions under which a vessel can depart for coastal navigation, thus deviating from the normal conditions required for SNF transport. Consequently, it is not necessary to consider such loads when evaluating the integrity of SNFs under normal transportation conditions.

• Journal of the Korean Institute of Navigation
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• v.23 no.2
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• pp.23-27
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• 1999

When a ship is running in following and quartering seas and on a crest with the ship′s length being nearly the same as the wave length, ship′s stability will be lost most; "T" shape crests with highly concentrated energy will appear during the process of transformation from irregular waves to regular ones, and the ship may be under continuous impact of large waves for a long period of time; Synchronism will also appear when the ship′s natural period of rolling and period of encounter are close to each other. For safe navigation, proper stability should be well ensured, proper speed and course chosen with speed under 1.8L1/2 kn (L is the ship′s length), initial listing avoided, special attention paid to steering.

• The KSFM Journal of Fluid Machinery
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• v.16 no.2
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• pp.42-47
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• 2013

Ship stability prediction is very complex in reality. In this paper, risk based approach is applied to predict the probability of a certified ship, which is effected by the forces of sea especially the wave loading. Safety assessment and risk analysis process are also applied for the probabilistic prediction of ship stability. The survival probability of ships encountering with different waves at sea is calculated by the existed statistics data and risk based models. Finally, ship capsizing probability is calculated according to single degree of freedom(SDF) rolling differential equation and basin erosion theory of nonlinear dynamics. Calculation results show that the survival probabilities of ship excited by the forces of the seas, especially in the beam seas status, can be predicted by the risk based method.

• 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 Fisheries and Ocean Technology
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• v.47 no.3
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• pp.248-256
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• 2011

The inherent efficiency of a ship would be prior to any other quality factors in ship's safety, because lack of it may give rise to a serious sea casuality even if it were a light mistake in operation. And the representative casualty comes from a deficiency of stability and an operating error combined would be capsizing. The Korean offshore large purseiner looks to have a structural weak point with small range of stability in spite of her big initial metacentric height, and have various type of roll reduction devices in order to cover up the defect. The aim of this study is to grasp for the roll reduction characteristics of the purseiner with bilge keel only and a stern keel additionally attached. The results are summarized as follows; The rolling angle of the model ship was increased in accordance with increase of the wave period and height, especially at close to the natural wave period of her, and the trends were more distinguished in the situation of bilge keel only installation than in the stern keel additionally installed. And stern keel has not noticeable effect on the reduction of the roll in the light ship condition, but has a little effect in full load condition.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.37-41
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• 1995

In order to analyze the rolling motion of a ship in random beam waves we use the partial stochastic linearization method. The quadratic damping and the nonlinear restoring moments given by the odd polynomials up to the 11th order are added to a single degree of freedom linear equation of roll motion. The irregular excitation moment is assumed to be the Gaussian white noise. The statistical characteristics of the response by the partial stochastic linearization method is compared with results by the equivalent linearization method and Monte Carlo simulation. It is fecund that the partial stochastic linearization method is not necessarily superior to the equivalent linearization method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.1014-1023
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• 2014

In this paper the real life operation of ULCS (Ultra Large Container Ships) is presented from the point of view of shipmasters. The paper provides interpretation of results of questionnaire filled by masters of large container ships during Tools for Ultra Large Container Ships (TULC) EUI FP7 project. This is done in a way that results of questionnaire are further reviewed and commented by experienced master of ULCS. Following phenomena are subject of questionnaire and further discussed in the paper: parametric rolling, slamming, whipping, springing, green water and rogue waves. Special attention is given to the definition of rough sea states as well as to measures that ship masters take to avoid them as well as to the manoeuvring in heavy seas. The role of the wave forecast and weather routing software is also discussed.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.39-45
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• 1993

In order to analyze the rolling motion of a ship in random beam waves we have used the equivalent linearization method. The quadratic nonlinear damping, the cubic and quintic nonlinear restoring moments were added to a single degree of freedom linear equation of roll motion. The irregular excitation moment was assumed to be the Gaussian white noise. The statistical characteristic of the response by the equivalent linearization method was compared with the simulation result.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.4
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• pp.398-408
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• 2016

Based on non-completely hybrid flow line scheduling of panel block in shipbuilding, several uncertain factors influencing the problem were analyzed in a real environment, and a nonlinear integer programming model was built for each sub-scheduling problem. To narrow the difference between theory and application, rolling horizon and rescheduling methods are proposed. Moreover, with respect to the uncertainty of processing time, arriving time and due time, we take the minimizing of the early and delayed delivery costs as the objective, and establish an evaluation with a global penalty function. Finally, numerical experiments and a simulation analysis were undertaken to demonstrate the effectiveness of the model and algorithm.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.3
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• pp.62-68
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• 2010

In the engineering field, sloshing in rolling vessel is a hot issue because of the connection with ship stability problem. The sloshing phenomena also can be utilized in the field of structure or facility vibration damper. This paper explores the possibility which sloshing of multi-particles can be used to dissipate energy in a rolling container. This energy dissipation can be utilized to the application of rotating damper. Some of the parameters expected to dissipates energy, such as vessel size, particle size, mass fraction and ramp height, have been experimentally and theoretically studied.