• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.318-323
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• 2014

When a disabled ship is being towed in a seaway, the speed and direction of the towed ship are estimated by using the towing force and direction of the selected tug boats at the predicted sea conditions including the wind and currents. In this paper, prediction method at the towing conditions of the various towing operations for a disabled ship are studied. The proposed calculation method suggests firstly the method to import the speed and resistance of the forward direction of the towed ship calculated by the existing computer program, second, the method to calculate the speed and resistance of the towed direction of the towed ship acquired from the selected tug boats at the initial towing conditions and lastly, the method to calculate the speed and resistance of the towed direction for the towed ship at the stable towing conditions. These calculation methods have been applied to the computer program and this program has been approved to be a useful program, capable of appropriately predicting the towed ship's conditions.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.637-642
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• 2013

In this paper, an analysis results of towing force and towing points which are dominating factors to determine the behavior of towed ship are introduced. The towing force and towing points to achive the desired posture and its position of the towed vessel are derived based on simplified dynamics and linearization method. LQR algorithm for posture control is applied to linearized system and numerical simulation is also executed. Force based on COG(cneter of gravity) and gain of controller to achieve desired posture for target vessel are obtained by using Riccati matrix equation and pseudo inverse matrix is applied to analyze the relation between the derived force and its towing point. Based on this analysis method, towing force need to move the towed vessel from its initial position to target position can be calculated. The towing method including towing point and direction is also considered on this method. Finally, the relation between towing force and towing point is confirmed from the analysis and the results can be applied to arrangement of tug boats during salvage works.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.249-249
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• 2012

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.2
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• pp.159-164
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• 2016

It is one of the important processes to predict the resistance of the towed ship when towing a disabled ship on the sea. Besides the basic resistance of hull itself, there are various added resistance, especially the added resistance due to waves can be considered one of the biggest component. In this paper, the algorithm which predict the added resistance due to waves of a disabled ship by theoretical analysis method of ISO 15016 standard was established, and realized as a computer program. The calculated result for an example ship was compared with existing standard one, and it is considered that this algorithm and computer program are appropriate to use for predicting the resistance and towing force of the disabled ship actually.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.4
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• pp.298-303
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• 2015

When a disabled ship is being towed in a seaway, the resistance increase of the towed ship caused by both the external conditions such as wave and wind and the hull conditions such as drifting angle, should be accurately predicted. Most of the disabled ships cannot be towed in the front direction of hull, but they are usually towed in drifted direction with some drifting angle. In this sense, the resistance increase caused by the drifting angle is not an element to be ignored. In this paper, various methods for prediction of the resistance increase caused by the drifting angle are studied. In addition, new prediction methods such as front-lateral projected ratio method and empirical formula method by multiple regression analysis have been derived. The front-lateral projected area ratio method has been applied to a computer program for prediction of the towing condition, and this method has been approved to be a useful method in practical situations.

• Proceedings of KOSOMES biannual meeting
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• 2008.05a
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• pp.55-59
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• 2008

The tug boat is restricted in her maneuvering ability due to the towed barge, and tug-barge have been strongly affected by the external forces, i.e. the wind, wave, currents, and so on. Therefore it is difficult to get the safety if tug-barge operation. In this study, we propose the basic method to develope the safety towing system for barge using portable GPS which is easily movable and relatively inexpensive. Then we have conducted the test on the real barge and discuss the results.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.833-838
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• 2010

The Supreme Court in Korea judged the conduct of vessels in narrow channel was applied in order to prevent a ship collision in narrow channel, regardless of kind of a ship or weather situation, as application was not excluded as vessel restricted in her ability to manoeuvre without other special circumstances such as receiving the right of keep her course and speed from the other vessel, any priority was not guaranteed for vessel restricted in her ability to manoeuvre in regard to the other vessel following the conduct of vessel in narrow channel. In this judgement, there is concern to cause disorder to interpretation in the rule of narrow channel and responsibility between vessels. Therefore, this study aims to suggest correct interpretation about the rule concerned.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.405-411
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• 2014

It needed the calculation of the required tugboat's power to move the damaged vessel to the safe area for reducing the additional damages. In this paper, it was verified the theoretical calculation method on the required power of tugboat through the 93m real ship tests. From the experiments, it was considered that the theoretical calculation method was sufficient to estimate the required power of tugboat. The resistance of the locked propeller was relatively big portions compared with other static resistances such as air resistance, frictional resistance and residual resistance. And dynamic resistance induced by swing movement and yawing was continuously occurred and it also was great effects on the total resistance. In the future, the safety factor will be considered and the exact prediction of ship's resistance will enhance the efficiency of tugboat because of the minimization of safety factor.