• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.744-752
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• 2007

Recently a fuel oil of the diesel engine in the ship is being changed with low quality as the oil price is higher more and more. Therefore the wear and corrosion in all parts of the engine like cylinder liner ring groove of piston crown, spindle and seat ring of exhaust valve are increased with using of heavy oil of low quality In particular the degree of wear and corrosion in between valve spindle and seat ring are more serious compared to the other parts of the engine due to operating in severe environment such as the high temperature of exhaust gas and repeating impact. Thus the repair weld to the valve spindle and seat ring is a unique method to prolong the life of the exhaust valve in an economical point of view In this study. corrosion property of both weld metal zone and base metal was investigated with some electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram and polarization resistance etc. in 5% $H_2SO_4$ solution. in the case of being welded with some welding methods and welding materials to the exhaust valve specimen as the base metal. In all cases. the values of hardness of the weld metal zone were more high than that of the base metal. And their corrosion resistance were also superior to the base metal. The weld metal of A2F(AC SMAW: 2 pass welding with foreign electrode) showed a relatively good results to the corrosion resistance as well as the hardness compared to the ether welding methods and welding materials. Moreover it indicated that hardness of the weld metal by the domestic electrode was considerably high compared to that of the foreign electrode.

• Journal of Ocean Engineering and Technology
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• v.22 no.3
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• pp.82-88
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• 2008

The diesel engine of the merchant ship has been aperated in severe environments more and more, because the temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing use of heavy oil of law quality, due to the significant increase in the price of oil in recent some years. As a result, the degree of wear and corrosion between exhaust valve and seat ring is more serious compared to other engine parts. Thus the repair welding of exhaust valve and seat ring is a unique method to prolong the life of the exhaust valve, from an economical point of view. In this study, the corrosion property of both weld metal and base metal was investigated using electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and polarization resistance in 5% H2SO4 solution. The test specimen was a part of an exhaust valve stem being welded as the base metal, using various welding methods. In all cases, the corrosion resistance as well as hardness of the weld metal zone was superior to the base metal. In particular, plasma welding showed relatively good properties for both corrosion resistance and hardness, compared to other welding methods. In the case of DC SMAW (Shielded metal arc welding), corrosion resistance of the weld metal zone was better than that of the base metal, although its hardness was almost same as the base metal.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.6
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• pp.1036-1043
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• 2022

This paper discusses about the development of a visual sensor that can be installed in an automatic mooring device to detect the berthing condition of a vessel. Despite controlling the ship's speed and confirming its location to prevent accidents while berthing a vessel, ship collision occurs at the pier every year, causing great economic and environmental damage. Therefore, it is important to develop a visual system that can quickly obtain the information on the speed and location of the vessel to ensure safety of the berthing vessel. In this study, a visual sensor was developed to observe a ship through an image while berthing, and to properly check the ship's status according to the surrounding environment. To obtain the adequacy of the visual sensor to be developed, the sensor characteristics were analyzed in terms of information provided from the existing sensors, that is, detection range, real-timeness, accuracy, and precision. Based on these analysis data, we developed a 3D visual module that can acquire information on objects in real time by conducting conceptual designs of LiDAR (Light Detection And Ranging) type 3D visual system, driving mechanism, and position and force controller for motion tilting system. Finally, performance evaluation of the control system and scan speed test were executed, and the effectiveness of the developed system was confirmed through experiments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2052-2060
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• 2017

The SOLAS ship should carry at least 83 different types of equipment based on the SFI group codes and each of which consists of several to dozens of components. During ship operation, it is necessary to ensure the normal operation of such equipment, and remote maintenance is highly demanded for immediate repair in the event of a equipment fault. This study proposes to find suitable classification system and to derive database structure for remote maintenance of navigation and communication equipment. As a result of this study, the classification system of equipment should be layered into equipment type, model, and component, and main table in the database consists of FMEA, service history, case data through Q&A, Preventive Maintenance. A database was constructed for 140 navigation and communication equipment models and 750 components. In order to evaluate the practical effects, service engineer evaluated the usefulness using the cloud app.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.980-991
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• 2023

To prevent accidents near the quay caused by a ship, ports are generally designed and constructed through navigation and berthing safety assessment. However, unpredictable accidents such as ship collisions with the quay or personal accidents caused by ropes still occur sometimes during the ship berthing or mooring process. Automatic mooring systems, which are equipped with an attachment mechanism composed of robotic manipulators and vacuum pads, are designed for rapid and safe mooring of ships. This paper deals with a displacement and velocity measurement system for the automatic mooring device, which is essential for the position and speed control of the vacuum pads. To design a suitable system for an automatic mooring device, we first analyze the sensor's performance and outdoor environmental characteristics. Based on the analysis results, we describe the configuration and design methods of a displacement and velocity measurement system for application in outdoor environments. Additionally, several algorithms for detecting the sensor's state and estimating a ship's velocity are developed. The proposed method is verified through some experiments for displacement and speed measurement targeted at a moving object with constant speed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.77-82
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• 2004

This study presents reliability assessment of merchant ships with focus on hull girder ultimate limit state, taking into account the time-dependent effects of corrosion, fatigue cracking and local denting. Some considerations for establishing a reliability-based repair and maintenance scheme are also made so as to keep a ship's hull girder strength reliability at an acceptable level even later in life.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.763-765
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• 2015

선박 수리 업무는 각 수리업체가 자체적으로 진행하고 있다. 업무를 진행하는 업체의 특성에 맞추어 업무분류를 산출하고 수리가 진행되고 있다. 따라서 실제 업무를 진행하는 외주업체는 정형화 되지 못한 업무성향에 따라 혼돈이 발생한다. 본 논문에서는 선박수리 업무를 분류하여 수리장비 및 인력정보 표현방법과 이를 활용하는 방법을 상세하여 수리업무의 차질이 발생하지 않도록 한다. 업무분류를 통하여 수리관리업체 및 외주업체는 더욱 밀착된 협력관계를 유지할 수 있도록 한다.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.93-94
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• 2006

The repair welding of small leakage parts on the water pipeline in engine room is often and important factor in standby and emergency condition in a ship. So, the purpose of this study is to evaluate the corrosion characteristics of welding part of leakage water pipe in case of some underwater welding electrodes. The corrosion current density between welding metal and base metal was considerably different according to used underwater welding electrodes. In case of DC welding, its corrosion characteristics was better than that of AC welding.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.4
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• pp.428-434
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• 2014

Dry docks are used to repair warships or Merchant ships based on their life cycles. There are the certain number of dry docks in the ROK Navy, However, the ROK Navy force structure has been changing a lot since the Korean War. The focus of this study is to analyze the queueing problem regarding present dry docks capacities and to forecast the appropriate number of dry docks based on future naval ship structure. The study proposes to obtain an efficient dry dock size using queueing problem and simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.412-415
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• 2014

선박은 항시 수리를 해야 하며 우리나라 역시 선박수리 산업은 발전을 거듭해오고 있다. 그러나 현재 선박 수리 산업의 일정관리는 60~70년대의 수기대장관리에서 벗어나지 못하고 있다. 이러한 불편함을 해결하고자 선박수리 산업에 ICT기반 일정관리가 필요하다. 본 논문에서는 앞서 언급한 문제를 해결하기 위해 선박수리 산업에 일정관리 기능을 부여하며, 부여된 일정관리를 위하여 선박수리 공무담당관의 빠른 의사결정을 지원하는 기법을 제안한다. 제안하는 기법은 다양한 입찰방법에 따른 관리업체 및 외주업체의 인력 그리고 장비의 현황을 근거로 최적의 의사결정을 지원한다.