• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.3
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• pp.265-274
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• 1990

The temperature inversions were studied on the basis of Digital Memory Bathythermography(DBT) data collected by training ship, Pusan 402, of the National Fisheries University of Pusan in August 23~25, 1986 and Fisheries Reserach and Development Agency of Korea in August, 1986, The results were as follows; Among the 67 stations of studied area, occurrence frequency of temperature inversion was 58.20%, And the frequency of onefold occurrence of temperature inversion at its profile of each station was 13.42%. of twofold occurrence was 20.80%, and of threefold occurrence was 23.88%. In the studied area, the temperature inversion usually occurred below the 40m depth and its layers also located below the thermocline. The temperature range of its inversion was from 14$^{\circ}C$ to 16$^{\circ}C$. The temperature inversion in the study area was oaused by the interaction between Tsushima Warm Current and Korea Coastal Waters.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.2
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• pp.61-71
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• 2009

In this paper, we propose a low-cost and compact motion capture system which enables to play motion games in PS2(Play Station 2). Recently, motion capture systems which are being used as a part in film producing and making games are too expensive and enormous systems. Now days, motion games using common USB camera are slow and have two-dimension recognition. But PSD sensor has a few good points, such as fast and low-cost. In recently year, 3D motion capture systems using 2D PSD (Position Sensitive Detector) optic sensor for motion capturing have been developed. One is Multi-PSD motion capture system applying stereo vision and another is Single-PSD motion capture system applying optical theory ship. But there are some problems to apply them to motion games. The Multi-PSD is high-cost and complicated because of using two more PSD Camera. It is so difficult to make markers having omni-direction equal intensity in Single-PSD. In this research, we propose a new theory that solves aforementioned problems. It can measure 3D coordination if separated two marker's intensity is equal to. We made a system based on this theory and experimented for performance capability. As a result, we were able to develop a motion capture system which is a single, low-cost, fast, compact, wide-angle and an adaptable motion games. The developed system is expected to be useful in animation, movies and games.

• Journal of Information Technology and Architecture
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• v.9 no.2
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• pp.177-186
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• 2012

Navy establishes the Naval Task Forces (TF) for many kinds of maritime operations. Then the TF in the maritime environment performs simultaneous component operations such as ASUW (Anti-Surface Warfare), ASW (Anti-Submarine Warfare), AAW (Anti-Aircraft Warfare), and assault operations. The TF consists of many tactical systems for the completion of missions C4I, VOIP (Voice Over Internet Protocol), DMHS (Digital Massage Handling System), and TDLs (Tactical Data Links) such as LINK-11, 16, ISDL (Inter Site Data Link). When the TF executes naval operations to complete a mission, we are interested in the kill chain for the maritime operations in the TF. The kill chain is a standard procedure for the naval operations to crush enemy defenses. Although each ship has a procedure about a manual for 'how to fight', it leave something to be desired for the TF detailed kill chain currently. Therefore, in this paper, we propose the naval TF's kill chain to perform the naval operations. Then, the operational effectiveness of the TF in the kill chain environment is determined through operation scenarios of TDL system implementation. It is to see the operational information sharing effect to a data link model based on MND-AF OV 6c (statement of tracking operational status) in the maritime operations applied to TDL and is to identify improvements in information dissemination process. We made the kill chain of maritime TF for the effective naval operations.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.2
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• pp.71-81
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• 1987

Nowadays, the high development of industrial technique demands the optimal design of marine structures to be welded under the water, because the underwater welding of the ship hull and marine structures can decrease manpower and cost of production. However there is not available at present any report on fatigue behavior about underwater welded joints. In this paper under tention- tension repeated fatigue stress with frequency of 10 cycles per second by local controlled system, the fatigue strength properties of underwater welded joints of SM41A-2 Plate-to-Plate of 10 mm thickness were experimentally examined. The results obtained were as follows : 1) The fatigue strength of underwater welded joints of SM41A-2 was peaked at the heat input of about 1, 400 joule/mm(180 A, 36 V), while, at the heat input of more than about 1, 100 joule/mm (160 A, 33 V) that of the underwater welds at the higher than cycle of life rather than the lower cycle was higher than that of the base metal but lower than that of the atmosphere welds on account of both cooling and notch effects. 2) The fatigue limit of underwater welds increased with an increase of heat input resulting in a peak of that at the heat input of about 1, 400 joule/mm and then decreased gradually. 3) The fatigue strength at N cycles was peaked between the heat input of about 1, 400 and 1, 700 joule/mm where the strain was rapidly increased. 4) It was confirmed that the optimal zone of heat input condition for obtaining the underwater welds fatigue strength higher than that of the base metal exists, and if out of this zone, the fatigue strength of the underwater welds was lower than that of the base metal because of lack weld penetration, inclusion of slag, voids, etc. 5) By the fatigue test, the underwater welds fractured brittly without visual deformation, so the strain was remarkably less than of the atmosphere welds. 6) The fatigue life factor was peaked at the heat input of about 1, 600 joule/mm (200 A, 36 V) at which the mean strain is a little higher than that of the base metal but quite lower than those of the atmosphere welds, resulting in good underwater welds because both fatigue strength and ductility of the underwater welds are higher than those of the base metal at such heat input.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.911-917
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• 2015

The objective of this work focuses on the analysis of injection rate and macroscopic spray behavior characteristics with injection pressures as well as combustion and exhaust emission characteristics with injection timing and injection pressure by using a common rail single-cylinder diesel engine. The injection rate was measured by applying the Bosch method, and macroscopic spray behavior characteristics were analyzed with a constant-volume vessel and a high-speed camera. In addition, combustion and emission characteristics were analyzed in a common-rail single-cylinder diesel engine with precise control of fuel injection timing and pressure. For injection pressures of 30MPa and 50MPa, the injection rate was higher at 50 MPa, and the spray development (penetration) was also higher in the same elapsed time. The peak in-cylinder pressure and rate of heat release showed a tendency to decline as injection timing was delayed, and the peak in-cylinder pressure and rate of heat release were slightly higher for higher injection pressures. Higher injection pressures also reduced the mean effective pressure, while the indicated mean effective pressure and torque increased as injection timing was delayed to TDC. Nitrogen oxides had a peak level at injection timings of $BTDC20^{\circ}$(30MPa) and $BTDC15^{\circ}$(50MPa); carbon monoxide emissions were reduced by delaying injection timing from $BTDC30^{\circ}$.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.744-753
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• 2015

This paper presents the results of research on developing marine unified communications to provide VoIP service based on marine satellites. With the recent popularity of smart-phones and other mobile devices, the demand for Internet-based wired and wireless unified technology has been growing in marine environments, and increasing interest is being directed to VoIP products and service models with high price competitiveness and the ability to deliver a variety of services. In this regard, this research designed three instruments, developed their unit modules, and verified their performances. These three instruments included the following: (1) a marine VoIP module equipped with an analogue gateway that can be linked to the existing devices used in vessels, which is more than 80% smaller than that of a land system; (2) a text/voice/video engine for marine satellite communications that runs on technology that minimizes communication data usage, which is a core technology for a marine VoIP service; and (3) a unified communication service that can support multilateral cloud-based message conversations, telephone number-based call functions, and voice/video calling between a private space in a ship and shore.

• Journal of Navigation and Port Research
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• v.33 no.10
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• pp.723-734
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• 2009

Container Vessel is becoming larger and faster thanks to the rapid growth of global trade and development of technology. Therefore, 15,000TEU vessel is expected to be ordered in near future. Every nations in north-east Asia are facing strong competition to be logistics hub to get the initiatives of logistics in response to the rapid change of logistics environment. According to the globalization of economy and major ports in this region also are trying to catch big shipping line for their survival. Considering above circumstances of the advent of ultra-large container vessel and spoke-and-hub strategy, it is inevitably necessary to make a fast and accurate vessel job in the terminal in order to be a leading port To meet this objective, current vessel planning system has to be improved innovatively. Therefore, this thesis propose multi distributed vessel planning system which enables multi loading/discharging planning with several planner simultaneously for faster and more accurate than existing planning and enhances quality of planning through information sharing among planners. Also this thesis uses simulation through Arena to verify the efficiency of this multi-distributed vessel planning system.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.217-225
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• 2014

The system that covers gathering, integrating, exchanging, presenting and analyzing of information within ships and shores for the safety and security in Marine Environment is known as e-Navigation Policy. Northern Europe has been conducting research and development. It came up into a concept that deals with ship's route information between vessels as well as vessels to shores which is better known as route exchange system. The research showed substantial advantages on navigational safety by exchanging the route information between vessels in vicinity and vessels to shores. Therefore, upon the adaptation of route exchange System as a major function in integrated navigational system, the existing procedures in VTS could be changed for betterment. In this study, it was verified the effectiveness of route exchange system by the adaptation of a recent collision accident occurred in Korean coast and suggested that route exchange system which would be carried out by the discretion of VTS center in VTS area. Finally, it proposed the new functions for outstanding services and procedures of integrating traffic organization services on coastal VTS for an effective route exchange system in Korean coastal area.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.655-662
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• 2016

This study proposes that a diving supervisor, who can perform the role of both a field manager and a supervisor, be introduced in the national qualification system. The goal was achieved by surveying the general status of the commercial diving sector, including the statistics of an underwater construction company, commercial diving equipment operation condition, diver working hours, diver supply and demand status, and underwater construction market size. The national qualification and national competency standard (NCS) systems were also analyzed to deduce the role definition and work scope of the diving supervisor. Consequently, the following proposition is made: the diving supervisor should be an "on-site manager with the highest job skill in the commercial diving field, who can perform the on-site process management as well as guide, supervise, and educate project participants and serve as an intermediary between the contractor and the workers." The responsibilities of the diving supervisor are proposed to include "diving planning and operation of the diving team," "diving with surface-supplied air and mixed-gas diving system," "chamber operation," "underwater construction," and "ship salvage." The persistent issues in commercial diving sectors, such as diver career development, management, and worker supervision, are expected to be largely resolved with the introduction of this qualification.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.535-545
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• 2019

The PBA of ship weapon system should be installed and operated under harsh environmental conditions and so it should be highly reliable to endure the mission profiles during its entire lifetime. In the case of PBA failure during operation, rapid maintenance is highly likely to be difficult due to problems such as supply of parts, which can have a devastating effect on the mission. In order to validate the reliability of PBA, a series of tests are performed with PBA samples, but they require time, testing facilities, samples, expenses and failure analysis if failed. The reliability of PBA is predicted on the basis of specifications such as MIL-HDBK-217F, but this specification does not take into account failure mechanisms for specific design details, environment and usage, interconnects and its characteristics that drive many failures of PBA in the field. Therefore, this study predicts the reliability of PBA using an RPA tool and proposes the RPA methodology as a validation process at the design stage. With RPA, it is now possible to achieve design validation including inherent failure mechanism, identification of weakest link, alternative design options, and test plan development.