• Journal of Ocean Engineering and Technology
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• v.30 no.5
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• pp.400-404
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• 2016

This paper presents experimental results for the vibration characteristics of the small unmanned underwater vehicle (UUV) OPKO 300, which was designed and manufactured by Daewoo ship and Marine Engineering Ltd. The autonomy of UUVs has led to an increase in their use in scientific, military, and commercial areas because their autonomy makes it possible for UUVs to be utilized instead of humans in hazardous missions such as mine countermeasure missions (MCM). Since it is impossible to use devices based on electromagnetic waves to gather information in an underwater environment, only sonar systems, which use sound waves, can be used in underwater environments, and their performance can strongly affect the autonomy of a UUV. Since a thruster system, which combines a motor and propeller in a single structure, is widely used as the propulsion system of a UUV and is mounted on the outside of a UUV’s stern, it can generate vibration, which can be transferred throughout the shell of the UUV from its stern to its bow. The transferred vibration can affect the performance of various sonar systems such as side-scan sonar or forward-looking sonar. Therefore, it is necessary to estimate the effect of the transferred vibration of the UUV on the sonar systems. Even if various numerical methods were used to analyze the vibration problem of a UUV, it would be hard to predict the vibration phenomena of a UUV at the initial design stage. In this work, an experimental study using OKPO 300 and an impact hammer was carried out to analyze the vibration feature of a small real UUV in the air. The frequency response function of the vibration based on the experimental results is presented.

• Journal of Ship and Ocean Technology
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• v.5 no.1
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• pp.1-13
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• 2001

As Indonesia determines to increase its marine fishery production, the development of tradi-tional boatyards has to be included in the agenda as it will give the local fishing communities a better chance to compete with large capital intensive fishing companies. It will also spread job opportunities evenly throughout the country instead of concentration fishing vessel con- struction in a few large shipyards located primarily on the highly populated island of Java. However development every single boatyard in indonesia would not only be prohibitively ex-pensive, but it would also create social tensions as the introduced technology would not be immediately accepted by the rural societies whose own traditions are still culturally signif-icant. Both these problems can be reduced by developing a collaborative scheme between traditional boatyards and a larger shipyard. The shipyard, with modern facilities, can develop work packages containing knock down components which are then assembled in the tradi-tional boatyards. The work packages are planned and designed so that every component can be assembled with relatively simple tools. Radical changes can be avoided as new techniques can be introduced gradually, responding to the boatyard\\`s own requirements and aspirations. While this manufacturing procedure is conceptually straightforward its efficient implemen-tation is in practice complicated by the fact that each traditional boatyard has unique char-acteristics in terms of labour resources, technological capability, and transportation links. By developing a computer model to simulate the interaction between the main shipyard and small traditional a computer model to simulate the interaction between the main shipyard and small traditional boatyards work packages can be designed that ensure that activities at all manufacturing locations are efficient.

• Composites Research
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• v.19 no.5
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• pp.12-19
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• 2006

In this paper, conceptual structural design of the main wing for a small scale WIG(Wing in Ground Effect) among high speed ship projects, which will be a high speed maritime transportation system for the next generation in Rep. of Korea, was performed. The Carbon/Epoxy material was selected for the major structure, and the skin-spar with a foam sandwich structural type was adopted for improvement of lightness and structural stability. As a design procedure for the present study, firstly the design load was estimated through the critical flight load case study, and then flanges of the front and rear spars from major bending loads and the skin and the spar webs from shear loads were preliminarily sized using the netting rule and the rule of mixture. Stress analysis was performed by a commercial FEA code, NASTRAN. From the stress analysis results for the first designed wing structure, it was confirmed that the upper skin between the front spar and the rear spar was unstable fer the buckling. Therefore in order to solve this problem, a middle spar and the foam sandwich type structure at the skin and the web were added. After design modification, the structural safety and stability for the final design feature was confirmed. In addition to this, the insert bolt type structure with eight high strength bolts to fix the wing structure to the fuselage was adopted for easy assembly and removal as well as in consideration of more than 20 years fatigue life.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.3
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• pp.202-210
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• 2013

As incomes increase, interest in ocean leisure picks up. As a result, a lot of research and developments on hull form design and production of planing boats, mostly used for ocean leisure, are needed. Analysis in researches on resistance of planing boats shows that resistance characteristic of planing boats is different from resistance characteristic of general boats because the former is fast, and its wetted surface is very small. Using Savitsky formula widely used in the calculation of effective horse power in shipbuildingyards, and propulsion system and engine manufacturers, this study calculated total resistance of a research planing boat. Then it analyzed the flow characteristics of the planing boat through theoretical analysis and wind tunnel experiment, and computed air resistance and lift force by changes of speed and trim angle. It also compared and analyzed result of theoretical analysis and experiment of the ratio of air resistance to total resistance under variations of velocity and trim angle. When the study is used to estimate more accurate effective horse power, it is expected to remedy abuses of unnecessarily installing high-powered engine. As nature disasters due to abnormal changes of weather increase, interest in greenhouse gas grows. International Maritime Organization (IMO) legislated Energy Efficiency Design Index (EEDI) and Energy Efficiency Operational Indicator (EEOI) to reduce ship greenhouse gas emissions. But this index will be applied to over 400 tons ships, small ships, emitting more greenhouse gases than larege ships per unit power, will dodge the regulations. Thus, this study indicated a problem by calculating greenhouse gas emissions of an ocean leisure planning boat (a small ship), and suggested the need for EEDI of small ships.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.2
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• pp.173-180
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• 2018

Marine casualties of small fishing vessels (SFV) of less than 20 tons are frequent in Korea. The analysis was conducted to identify the cause and then prepared reduction plan using the marine casualty statistics of fishing vessels for the last five years from 2012 to 2016 by the Korean Maritime Safety Tribunal to reduce the marine casualties of SFV. According to the analysis of the type of whole vessels occurring marine casualty, fishing vessels accounted for an average 68.0 %; moreover, except for 2014 when M/V SEWOL ferry capsizing occurred, the rate of death and missing due to marine casualties occurred from 68.3 % to 91.2 % in fishing vessels, and an average 79.5 % was found to be urgent need of a measure. Marine casualties occurrence depending on the gross tonnage of fishing vessel was found that the most occurred at less than 5 tons, followed by the order of 5 to 10 tons or less. However, crews who boarded on SFV do not have any training program for them, except for the fishing safety training of fisher who carry out fishing for shipowners and crew of the coastal and offshore fishing vessel in accordance with the safety regulations for fishing vessels in the Fisheries Cooperative Association. Therefore, it is necessary to revise the training program so as to improve the preventive action and then emergency response including the fishing safety compliance with each fishery, safe navigation, machinery inspection and emergency response. Also, an SFV of less than 5 tons of 56,000 vessels is boarded by unqualified fishers. It would also be possible to consider subdividing small boat operator's certificate to enhance their qualifications. It is expected that marine casualties of SFV will be reduced if active efforts are made to improve the safety consciousness of fisher and shipowners as well as the reorganization of fishing safety training and the small boat operator's certificate system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.3
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• pp.480-490
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• 2018

Recently, The MRV (monitoring, reporting and verification) regulation, which measures, reports and verifies the emission gas of vessel to head for member countries of Europe Union (EU), is being implemented. As part this reason, we develop a system that estimates simple fuel consumption and recommends optimized stop-over ports of vessel, to calculate amount of carbon emission. To do this, we analyze fuel, distance and time consumption between port and the other port based on stored voyage data for over 10 years of real-ship, and implement a simple fuel consumption estimation module using analyzed result. Also, we design and implement the optimized route recommendation algorithm, existing navigation route display function including comparison with the optimized routes and user custom route plan function. Therefore, we expect the developed system is helpful when makes a navigation route and so on by reference indexes and we anticipate the system to have a sense for future research which learns and predicts for accuracy result.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.12
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• pp.1577-1588
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• 2018

Recently, many researches are progressing to support the operation and maintenance works of vessels using analyzed result based on various information of equipment. The interfaces of communication equipment are standardized very well, but the interfaces of machinery and other parts are not standardized yet. For that reason, there has limitations for data exchange and management. To solve the problem, the ISO is establishing new standards which are ISO 19847 for shipboard data servers th share field data at sea and ISO 19848 for standard data for shipboard machinery and equipment. In this paper, we developed a data management platform for shipboard machinery equipment, and tested the field data exchanging using the developed platform based on the standards. To do this, we analyzed the requirements of the standards and related researches, and designed an architecture of shipboard data platform that satisfied the requirements. Also, we developed components of the designed platform architecture and verified the effectiveness for it.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.73-78
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• 2004

For the preliminary stages of ship design it is necessary to develop a basic design, which specifies the main particulars of the vessel. based on the requirements given by the owner. An efficient design enables the shipyard to make a rough estimate of the construction costs and to put forward a favourable quote during the call for tenders. The parametric determination of the main particulars of the vessel involves the application of empirical formulae. These formulae have been created after detailed tests and research by maritime research institutions and researchers had been carried out. Here, the design of a medium sized Bulk Carrier (26000t dwt) with a service speed of 17 knots for carrying rice and rock phosphate has been illustrated. Medium sized Bulk Carriers (25,000t dwt - 50,000t dwt) are in steady demand among small shipping companies. They have a size advantage, in that port size restrictions do not affect their design tremendously. Nevertheless, structurally. they are one of the most difficult to build. During design, the rules of the maritime regulatory bodies were strictly adhered to.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1404-1409
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• 2003

The sway control problem of the pendulum motion of the container crane hanging on the trolley, which transports containers from the container ship to the truck, is considered in this paper. In the container crane control problem, the main issue is to suppress the residual swing motion of the container at the end of the acceleration, deceleration or the case of that the unexpected disturbance input exists. For this problem, in general, the trolley motion control strategy is introduced and applied to real plants. In this paper, we suggest a new type of swing motion control system for a crane system in which a small auxiliary mass is installed on the spreader. The actuator reacting against the auxiliary mass applies inertial control forces to the spreader of the container crane to reduce the swing motion in the desired manner. In this paper, we consider that the length of the rope varies is we design the anti-sway control system based on LMI(linear matrix inequality) approach. And, it will be shown that the proposed control strategy is useful and it can be easily applicable to the real world. So, in this study, we investigate usefulness of the proposed anti-sway system and evaluate system performance from simulation and experimental studies.

• Corrosion Science and Technology
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• v.19 no.5
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• pp.250-258
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• 2020

Recently, 5000 series and 6000 series Al alloys have been used as hull materials for small and medium-sized ships because of their excellent weldability, corrosion resistance, and durability in marine environments. Al ships can navigate at high speed due to their light weight. However, cavitation-erosion problems cause reducing durability of Al ship at high speed. In this investigation, 5052-O, 5083-H321, and 6061-T6 Al alloy materials were used to evaluate the damage characteristics with amplitude (cavitation strength). As a result of the electrochemical experiments, the corrosion current density and corrosion potential of 6061-T6 in seawater were 8.52 × 10-7 A/㎠ and -0.771 V, respectively, presenting the best corrosion resistance. The cavitation-erosion experiment showed that 5052-O had the lowest hardness value and cavitation-erosion resistance. 5052-O also had a very short incubation period. As the experiment progressed for 5052-O, pitting formed and grew in a short time, and was observed as severe cavitation-erosion damage that eliminated in large quantities. Among the three specimens, 5083-H321 presented the highest hardness value and the damage rate was the smallest after the initiation of pitting.