• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.810-817
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• 2018

In Korea, tuna purse seine fishery is the industry with the highest production volume in domestic deep-sea fishery. Research has been continuously carried out since the late 1980s, and research on modernization of technology has been actively conducted. However, while auxiliary works boats on the fishing vessels play an important role in the purse seine fishing, related research is not sufficient. In this study, we tried to rebuild the propulsion system of the Net-boat from the propeller to the waterjet type and to perform the hull form conversion to improve the resistance performance of the hull part and improve the motion performance. For this, we calculated the change of the fluid performance of the ship through computational numerical analysis. In addition, towing tank tests were carried out to verify the performance of the existing ship and the ship which changed the propulsion system. As a result, resistance performance of the waterjet type compared to the propeller type was improved by approximately 45 %. It was confirmed that this was due to reduction of the wetted surface area by removing net and improvements in hull form.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.605-607
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• 2011

A Study on the flow-structure characteristics of a 3/2 way pneumatic valve is essential for optimizing the performance of ship engines. It is important for the valve to have desirable safety factor am reduced weight from the safety and economic point of view. In this study, we capture flow-structure characteristics of 3/2 way pneumatic valve. This is optimized based on the proper design criteria. The air at a pressure of 30 bar is the working fluid which is made to fill in the tack in short time. This time is defined as the filling time. The flow and structure analysis is performed for three cases under maximum stress and safety factor. In optimum design, considering the flow-structure characteristics, we model twenty seven cases by using DOE(design of experiments) method Here, analysis for each cases is performed and then metamodels are created We obtain optimized parameters and then analysis is repeated to compare with the initial model. Finally, the feasibility of the optimum design is verified.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.79-84
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• 2009

Recently, the degree of navigating vessel's risk is increasing significantly by growing of vessel's volume and increasing of marine facilities, marine bridges and port development etc. As a result, Ministry of Land, Transport and Maritime Affairs generalized formal Maritime Safety Audit as a comprehensive maritime traffic safety management system in order to ensure safety improvements from the planing to maintaining of the development which influence to maritime traffic environment. A MSA is a formal safety performance examination of an existing or future fairway by an audit team. It qualitatively estimates and reports on potential risk of Maritime traffic safety and identifies the measure for improving in safety of human life and preservation of environment. This paper introduced the outline of MSA policy as the guideline for making audit reports is on its developing which is mainly processed by Maritime Safety Research Center, KST in cooperation with KMU, MMU and KORDI.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.139-148
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• 2020

The most important factor affecting the berthing energy generated when a ship berths is the berthing velocity. Thus, an accident may occur if the berthing velocity is extremely high. Several ship features influence the determination of the berthing velocity. However, previous studies have mostly focused on the size of the vessel. Therefore, the aim of this study is to analyze various features that influence berthing velocity and determine their respective importance. The data used in the analysis was based on the berthing velocity of a ship on a jetty in Korea. Using the collected data, machine learning classification algorithms were compared and analyzed, such as decision tree, random forest, logistic regression, and perceptron. As an algorithm evaluation method, indexes according to the confusion matrix were used. Consequently, perceptron demonstrated the best performance, and the feature importance was in the following order: DWT, jetty number, and state. Hence, when berthing a ship, the berthing velocity should be determined in consideration of various features, such as the size of the ship, position of the jetty, and loading condition of the cargo.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.573-586
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• 2022

Corrosion can cause dangerous and expensive damage and failures of ship hulls and equipment. Therefore, it is necessary to maintain the vessel by periodic corrosion inspections. During visual inspection, many corrosion locations are inaccessible for many reasons, especially safety's point of view. Including subjective decisions of inspectors is one of the issues of visual inspection. Automation of visual inspection is tried by many pieces of research. In this study, we propose image preprocessing methods by image patch segmentation and thresholding. YOLOv5 was used as an object detection model after the image preprocessing. Finally, it was evaluated that corrosion detection performance using the proposed method was improved in terms of mean average precision.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.1
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• pp.37-45
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• 2011

Reduction of ship's rolling is the most important performance requirement for improving the safety of the crew on board and preventing damage to cargo as well as improving the comfort of the ride. It is a common experience for mariners, to see that steering with a rudder generally induces rolling of the ship, though the original aim of the rudder is to keep the ship's heading to the required course. At the first stage, when a rudder is steered, usually a ship heels in an inward direction, due to the roll moment acting on the rudder. At the next stage in steering, the main heel may change to an outward. This coupling between rudder and roll motion has become an attractive problem from the point of view of roll stabilization using the rudder, because it is a natural in sight that if the rudder action is skillfully related to the change of roll as well as to the course deviation, the roll can be reduced to a certain degree. The main aim of this paper is to discuss the results of the actual full-scale sea trials carried out on steer gear No.1 and No.1 2, the individual quartermaster and to make clear their statistical properties, using the actual data which included measurement of roll angle, roll rate and the comparative tests were carried out immediately after each other, in order to minimize any statistical variation in sea conditions. It can be concluded that the steer gear No. 1 2 reduced the roll motion on average by about 21% in comparison with the No.1 and confirmed the some difference as per a ability of quarter-master's maneuver.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.7-12
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• 2005

A ship can be considered as a large human-machine system and the interaction between worker and system affects the work performed and its efficiency. Inside the bridge of a ship, there exist many auditory signals as well as visual signals. However, only a few studies have been performed related to human recognition to alarm systems in bridge. In this study, auditory icons and abstract sounds are compared to find more effective means of alarm systems. the study result shows tint auditory icons are recognized faster than abstract sounds. This result is expected to be used as a basic data for developing performance criteria of auditory display inside bridge and for designing integrated ship bridge alarm system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.1
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• pp.83-90
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• 2022

About 90.5 % of barge-towing tugs weigh less than 200 gross tonnage and most are served by the master alone. They are also not subject to the regulations on the working hours and manning levels stipulated in the Seafarers' Act. Therefore, the master of barge-towing tugs cannot take sufficient rest during the navigational watch. Moreover, barge-towing tugs do not satisfy the human seaworthiness due to the inevitable performance of the navigational watch which must be alternately undertaken with an unqualified person, called the "Boatswain". Furthermore, there are many cases in which the master or owner of a tug fails to comply with the additionally required minimum manning levels stipulated in the Ship Of icers' Act when a tug tows a barge. This study reviews the following: (1) the regulations on the working hours and manning levels that are stipulated in the Seafarers' Act, (2) the regulations on the minimum manning levels for ship of icers of the tug's deck part that are stipulated in the Ship officers' Act, (3) marine accidents in the barge-towing tugs. As a result I suggested that one additional deck officer should be on board when a tug tows a barge through the revision of the minimum manning level for ship of icer on the deck part in order to prevent marine accidents of tugs effectively. Especially, the Act on the Punishment, etc. of the Serious Accident came into effect on January 27, 2022. If marine casualties occur continuously at sea due by the same cause, and the cause of such marine casualties would be turned out by the fatigue of the ship of icer caused by insufficient institutional arrangements, the administrator of competent Authorities of Maritime and Port could be punished, so it seems to prepare for it.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.3
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• pp.70-75
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• 1997

This paper concerns with a safe and efficient transportation method of hot-coils on cargo ship. An automatic loading and unloading system of hot-coils by cassettes, which secure the geometrically unstable cargo, hot-coil, by supporting with wedges on both sides, is considered efficient and profitable. Safety of hot-coil on cassette and subsequently safety of total cargo ship are directly affected by the wedge angle of cassette. For optimal design of the cassette wedge angle, a dynamic model of hot-coil/cassette cargo is developed with constraint of no relative motions between the coil and the cassette. Force equilibrium conditions between resultant alternating inertia forces on hot-coil due to motions of cargo ship in waves and reactions forces from cassette wedge surfaces are derived and consequently a numerical simulation code is implemented. Cassette wedge angle of 37 degree is taken as optimal by considering dynamic stability of hot-coil and strength of cassette structure. Performance of the designed cassette wedge angle is investigated by scaled bench test.

• Proceedings of the KWS Conference
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• v.43
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• pp.213-215
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• 2004

Water jet propulsion system has high efficiency on middle to high speed, and it provides better safety than conventional screw propeller because it has not projected propeller and rudder. So many leisure boat and high-speed ferries use this propulsion system. We developed water-jet propulsion unit for small planning boat, and launched that in the boat, after that we tested water-jet unit in the lake. As a result, we certify heat dissipation at the bearing housing and reverse duct's shape for neutral position are important at the design, and alignment water-jet unit and keel line are important at the launching, and ship's resistance performance and jet's propulsion performance also are needed to consideration.