• Journal of Navigation and Port Research
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• v.42 no.3
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• pp.207-216
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• 2018

If empty containers from multiple shipping liners are mixed together in the same bay, then the space utilization increases; however, the expected number of re-handles also increases. Formulas for estimating the expected number of re-handles are derived for various storage strategies and two types of handling equipment. The expected number of re-handles is compared, through numerical experiments, among those cases. The results of the numerical experiments are used to analyze the change in the number of expected re-handles according to the change in the retrieval ratio and repair ratio. The impacts of the change in the bay size and the distribution of the storage and retrieval ratio of containers among multiple vessel liners on the expected number of re-handles are analyzed. It is necessary to study efficient operational strategies considering the expected number of re-handles for empty containers.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1137-1140
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• 2014

Faulty electric motors onboard vessels with anomalies in windings or poor insulation are usually repaired at land based workshops and reinstalled in place by crew hands after receiving the repaired motors. Especially for 3 phase induction motors which need Y-${\delta}$ starters with 6 lead wires, it would happen that the polarities of stator windings cannot be well distinguished if the original tags of these wires are erased or not visible clearly, resulting in subsequent damage to the repaired motor due to extreme current flow when the power is given to the motor the stator windings of which are wrongly connected in the polarity. This study proposes an easy way to make correct connection in winding polarities without failures based on the electro-magnetically induced voltages on windings when a slight DC current is supplied to a winding coil by using an analog multi-tester. The proposed method is applied to actual motors and delves into the applicability for polarity discrimination through a few measurements onboard vessels.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.299-305
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• 2014

In a ship-building, a transporter is the moving equipment to transport ship blocks from a workshop to another in a shipyard. The efficient scheduling of transporters has an important role for the operation of a building ship to be completed on schedule. There are the previous studies on the transporter scheduling for moving blocks in a shipyard. These studies have no consideration for the transporter combination to increase the productivity of moving blocks. This paper presents an efficient transporter scheduling model considering transporter combination explicitly. The objective of this model is to minimize the operational cost and maintain the workload balance among transporters. we also present three heuristics algorithms based on tabu search for finding the solution of the model. The efficiency of the proposed heuristics are verified with several computational tests.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1154-1158
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• 2007

현재 국내 하천에는 수많은 보가 존재하고 있으며, 하천에 설치된 보는 보 주변 지역에 많은 혜택을 제공한다. 보의 규모가 클 경우 소수력 발전을 위한 용도로 사용되거나, 선박 통행을 위한 수심 확보 목적으로 활용된다. 상수원으로서 농업용수와 생활용수를 공급하며, 홍수 시 상부 저수지를 홍수 조절을 위한 목적으로 활용되며, 지역 주민들에게 여가 활용의 기회를 제공한다. 이렇듯 하천에 설치되어 있는 보는 유용한 역할을 수행하지만 사용하고자 하는 용도가 없어지고, 노후화되어 보의 기능이 점차 약화되는 보들이 하천에 계속 남아있게 된다면, 필요 없이 하천을 막아 흐름을 정체시켜 결국 환경이나 생태적인 측면에서 커다란 손실을 가져오게 된다. 최근 농경지 도시화, 경작 방식의 변화, 취수시설물 통폐합, 시설 노후화 등으로 매년 수십 개 이상의 보가 폐기되고 있으나, 폐기된 보는 대부분 철거되지 않고 하천에 남아 여전히 문제를 발생시키고 있으며, 외국의 경우에는 이미 기능 및 용도를 상실한 보 철거는 하천 생태통로 복원 등의 목적을 위해 하천환경복원의 한 방법으로 널리 활용하고 있다. 특히 보의 기능 상실 여부는 단순한 시설물 노후 여부로 따지는 것이 아니라 본래의 기능을 상실하였을 경우에는 시설물이 노후화되지 않았더라도 적극적으로 철거하고 있다. 본 연구는 보 철거를 통한 하천생태통로 복원 기술 개발을 위한 연구의 일환으로 기능을 상실한 보 철거를 위한 보 철거 선정 체계에 대한 시안을 제시하고자 한다. 철거 대상 보 선정을 위해서는 보 관리주체 및 보 주변지역에 거주하는 주민의 역할이 중요하며, 이에 따라 보 철거 선정 체계는 보 철거를 위해서 보 주변 지역 거주민을 설득하며, 하천의 환경 개선을 위한 합리적인 대안 제시를 목적으로 하고 있다. 선정 체계를 바탕으로 주민 협의 및 대안 제시를 통해 결정된 대상 보는 선정 체계 안에서 보 철거 영향 판단 절차에 따라서 보 철거로 인한 수문, 수리, 지형, 수질, 생태 영향을 판단하게 되며, 이와 더불어 사회 경제적인 영향을 평가하게 된다. 평가결과에 따라서 보를 완전히 철거하거나 다른 대안을 고려하여 보를 부분적으로 철거하거나 개량하게 된다.

• Journal of the Ergonomics Society of Korea
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• v.30 no.1
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• pp.251-257
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• 2011

When designing a ship, ergonomic considerations are crucial when minimizing a navigator's fatigue due to the burden of work, and to appropriately operate the navigational equipment for each given situation by helping the operator to understand the surroundings as well as the physical functions of the ship. However, insufficient consideration of ergonomic elements in the actual design of ship Bridges is lowering the performance of safe navigation and allows for the possibility of operation or readout errors. Consequently, these errors lead to an increase in maritime accidents. Therefore, this study conducted a usability evaluation on the importance of and the usage frequency of navigational equipment, their influence on actual navigation, and the possibility of error upon operation or readout between training ship officers, to derive an optimized layout that includes the consideration of ergonomic factors for on-Bridge navigational equipment, which are currently arranged differently according to their type or size. The optimized layout of on-Bridge navigational equipment was carried out based on the evaluation results, using the Lingo program. Through the process of optimization, revised layouts of on-Bridge navigational equipments(control and display device) were suggested, considering emergency situations(ship collision, stranding, fire and explosion, sinking, etc.) during navigation.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.119-127
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• 2011

Overhaul and repair service means the sequential processes of disassembly, repair and reassembly for a product which has been used for a long time. Overhaul is required for the companies producing airplanes, ships, trains, military weapons and heavy industrial equipments which are very expensive and have a long life cycle. The most important performance measure of the overhaul repair shop is usually the lead time. Thus, how to design the manufacturing system to meet the delivery date is a major concern in overhaul repair shop. This paper introduces the case study of an overhaul repair shop producing military weapon systems with the 3D simulation tool, $QUEST^{TM}$. At first, the characteristics of overhaul shop and what should be considered for simulation modeling are explained. Then, various simulation scenarios including two types of disassembly systems, one is flow line system and the other is cell system, are discussed with the results of simulation experiments.

• Journal of Ocean Engineering and Technology
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• v.26 no.5
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• pp.63-72
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• 2012

The product lifecycle of a marine vessel can be classified into the design-production, operation-maintenance, and disposal phases. During the operation and maintenance phase, status data should be gathered from the major machinery and instruments installed on the marine vessel in order to perform efficient maintenance work. Although a PLM (product lifecycle management) system can manage the product information during the design and assembly stage, a PLM based on asset management technology is more appropriate for product information management during the operation stage. Product embedded information devices (PEIDs) are suggested for gathering real-time maintenance information during the operation and maintenance lifecycle. A PEID allows PLM to provide the capability of offering active information exchange between the lifecycle management system and equipment. This study designed a PEID to effectively obtain information and interact with a PLM system. It consists of sensors, wireless communication, and a micro-processor, which allow it to accumulate status data on the PLM system. The embedded information device and PLM enable the seamless information flow, tracking, and updating of MRO (maintenance repair and overhaul) information for a product throughout the middle of the product lifecycle.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1162-1167
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• 2006

The discharge of ballast water from the marine vessel without proper treatment causes the ecological disruption. Therefore, International Marine Organization(IMO) has the plan to force the proper treatment of ballast water before its discharge to open sea. To satisfy the IMO's criteria, several processes such as filtration, UV irradiation, and ozonation etc., were introduced. Since the disinfection of ballast water should be conducted within very short hydrolic retention time, electrochemical treatment can be a promissing process. The DSA(dimensional stable anode) electrode for the electrochemical treatment was prepared by thermal deposition method. The disinfection rate of microorganisms increased with the increasing current density and reaction time under low pH condition. The morphology of sterilized microorganisms was shown by SEM and Microscopy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3806-3813
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• 2012

The coastal environment is affected by Cu and Zn contamination through diverse routes, including antifouling agents, industrial wastewater, and domestic activities. In this study, Crassostrea gigas and Littorina brevicula were used to examine the distributions of Cu and Zn, which are related to the increase in the use of new antifouling agents that have been used for ships since the TBT ban in 2003. The average Cu and Zn concentrations in the samples were 231.8 ${\mu}g/g$ and 492.6 ${\mu}g/g$, respectively. Both the Cu and Zn concentrations were highest in the shipyard samples, followed by the harbor sample for Cu and the industrial area sample for Zn. The results indicated that the Cu concentration was affected by the antifouling agents, and the Zn concentration was affected by both the antifouling agents and industrial wastewater. The areas that need intensive control to address the Cu and Zn contamination in major Korean coasts were identified.

• 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.