• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.283-287
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• 2004

Arc welding is sometimes used to repair damaged cast iron parts in diesel engine for driving a ship. In this case cola arc welding. is good for. saving the time and results in good repairing. But if some difference in hardness on welding zones made with AWS E Ni-CI and NiFe-CI. happen, repaired parts would be cracked in a short. In order to overcome this default, the study is performed on varying preheating temperature of welding parts, selecting welding rod and welding work way. The result will be used on ship's repair working shop.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.899-908
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• 2021

It is expected that the global market for vessel repair and remodeling will grow up to the scale of about 25 billion dollars by 2023. Korea's shipbuilding industry is leading the world with its international competitiveness in design and production technology. The actual status of vessel repair industry, however, is poor as there are only two or three companies for vessel repair that can deal with large vessels in the area of Gyeongnam. The reason is that civil complaints are filed severely about environmental problems and environment-related regulations are so strict that it is fairly hard to get governmental approval for the operation of a vessel repair workplace. Domestic vessel repair companies mainly target small- and medium-sized vessels. There are only few workplaces that can carry out regular examination or repair work on large vessels such as LNG vessels, and due to the high price of vessel repair, most of the domestic repair work on large vessels including LNG vessels tends to be snatched by markets in Southeast Asia or China. Despite the tremendous domestic demand of Korea that has established the world's first shipbuilding industry and world's sixth biggest harbor infrastructure, its vessel repair industry can be said to be in very poor condition. In order to vitalize vessel repair industry, this study is aimed to analyze the environmental influence of vessel repair workplaces in Gyeongnam where vessel repair companies are concentrated and suggest standard processes by analyzing vessel repair processes precisely.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2489-2496
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• 2014

The existing ship repair tool management system based on hand writing has many problems such as frequent loss of tool and overdue. To solve this problem, same systems have adopted the bar-code system. However, the systems can't cope with a problem to substitute spurious tool for genuine one on bar-code damage. Therefore, additional validation steps are necessary in order to manage expensive ship repair tool. In this paper, we propose an image comparison method for ship repair tool management. To be more concrete, we propose a normalization method and determination conditions for image comparison to use characteristics of mobile device. The normalization method makes use of the characteristics of mobile device that provides functions of real time recording, overlapping and cropping images. The proposed method applies three conditions(sum of inner angles, size of angle, position of corner coordinates) into the comparison module. The implemented system shows good performance on change direction, lighting, size and etc. The accuracy is more than 95%.

• Journal of Ocean Engineering and Technology
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• v.20 no.2 s.69
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• pp.41-45
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• 2006

Arc welding is sometimes used to repair damaged cast iron parts in diesel engine for driving n ship. In this case cold arc welding is good for saving the time and results in good repairing. But if some difference in hardness on welding zones made with AWS E Ni-CI and NiFe-CI happen, repaired parts would be cracked in a short. In order to overcome this default, the study is performed on varying preheating temperature of welding parts, selecting welding rod and welding work way. The result will be used on ship's working shop.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.1-10
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• 2021

Recently, the repair and recycling of damaged mechanical parts via metal additive manufacturing processes have been industrial points of interest. This is because the repair and recycling of damaged mechanical parts can reduce energy and resource consumption. The directed energy deposition(DED) process has various advantages such as the possibility of selective deposition, large building space, and a small heat-affected zone. Hence, it is a suitable process for repairing damaged mechanical parts. The shaft is a core component of various mechanical systems. Although there is a high demand for the repair of the shaft, it is difficult to repair with traditional welding processes because of the thermal deformation problem. The objective of this study is to propose a repair procedure for a damaged shaft using the DED process and discuss its applications. Three types of cases, including a small shaft with a damaged surface, a medium-size shaft with a worn bearing joint, and a large shaft with serious damage, were repaired using the proposed procedure. The microstructure and hardness were examined to discuss the characteristics of the repaired component. The efficiency of the repair of the damaged shaft is also discussed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.339-344
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• 2006

The productivity for container hand1ing in container ship is a important role in container terminal, and it is mainly depended on the productivity of gantry crane. From the failure of gantry crane, the crane will be stopped until the repair of the failure. During the repair, the loading and/or discharging for container ship is suspended, and the productivities of the container ship and the yard is just hold. Thus, the prevention maintenance is importance to make a keep the steady state condition for all equipments in container terminal. In this paper, we deal with a optimal determination method of prevention maintenance interval for gantry crane systems. For verification, we will make a productivity of gantry crane and adapt to total container handling in each ship by simulation.

• Journal of Korea Port Economic Association
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• v.38 no.3
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• pp.69-86
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• 2022

This study analyses the necessity of the large-size shipyard and explores competitiveness factors of it. Furthermore, the competitiveness is evaluated and the economic feasibility of building and operation of shipyard is examined. As a result of AHP analysis of the determining factors of the competitiveness of the repairing shipyard, the importance of the factors was found in the order of arrival and departure safety, repair technology, dock and wharf facilities, repair cost, repair period (on time delivery), and repair parts supply. Moving distance, repair service quality, repair parts supply, arrival and departure safety, repair technology, dock and quay wall facilities, and repair period (on time delivery) were identified as key factors in the AHP analysis for competitiveness of the Busan Port repair shipyard to be built in the future. As a result of the analysing economic feasibility, the net present value of the Busan Port repair shipyard construction and operation investment project was KRW 435.6 billion, and the internal rate of return was 9.8%, higher than the social discount rate (4.5%), and the cost-benefit ratio (B/C) was high at 1.167. As a result of the study, the necessity and economic feasibility of the Busan Port repair shipyard are sufficiently ensured, and the competitiveness assessment was highly positive.

• Journal of Navigation and Port Research
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• v.32 no.2
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• pp.121-126
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• 2008

This paper presents hull stress monitoring system installed in LNGC damaged by a Typhoon Elongation/contraction of removed areas has been assessed in terms of possible residual stress that will take place in replaced blocks when the applied load is removed. The bending moment of a vessel changes actually in terms of loss of longitudinal members and the change of weight distribution in repair procedure. The change of bending moment affects mainly in hull stress of longitudinal members. Hull stress monitoring system was installed on upper deck to prove LNGC stable in the criteria to be less than 40MPa during the period of repair procedure. A temperature measuring system was also installed to exclude the additional stress due to thermal effect from the measured hull stress. As a result, the hull stress was modified with the data measured by the temperature measuring system. This hull stress considering thermal effect was used as a guide stress to check the safety of LNGC during the period of repair procedure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.5
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• pp.709-718
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• 2021

As regulations on environmental pollution of ships have been strengthened, interest in smart ships such as electric propulsion ships equipped with hybrid power systems is increasing. Since batteries used in electric propulsion ships have a larger capacity than batteries used in vehicles, the price is high and maintenance is considered important. The ship's battery is manufactured as an integral type and is managed by the battery management system, and the maintenance and repair of the battery is performed through the replacement of the battery. we design and implement a battery module and a control algorithm using pre-cell for easy battery management. In addition, a controller is designed to transmit the data necessary for the electric propulsion ship power system control to the power control system. When a battery to which the corresponding spare-cell is applied is used, the stability of the ship and the battery system is increased, and it can have an advantage in terms of maintenance and repair.

• Special Issue of the Society of Naval Architects of Korea
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• 2008.09a
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• pp.10-15
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• 2008

The proper docking block arrangement, loading condition and structural reinforcement are required to ensure structural safety of ship, when she is in re-docking and launching for inspection or repair. The large reaction force due to narrow bottom tangent area, heavy weight and ballast loading are occurred at aft body and fore body of ship. Especially, in case of LNGC, the strength evaluation is necessary for cargo hold areas including mid-body because tank hydro test is performed in dry-dock. The analysis results and experiences to confirm structural safety for docking of conventional LNGC$(138K{\sim}151.7K)$ are introduced in this paper.