• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.33-34
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• 2005

The internal state of an automotive engine is very severe. A piston exposes burnt gas of over $2000^{\circ}$ nd is shocked by high pressure at the time of explosion. Furthermore strong friction is caused by high speed motion. A study on the cooling of the piston requires because the cooling and lubrication of the piston has an effect on the life and efficiency of engine directly. The previous system of oil jet cooled only the bottom of the piston. In order to improve the cooling efficiency, the oil gallery is made inside the piston, and oil flows into the oil gallery. The flow rate of oil at the entrance of oil gallery is important because of the cooling efficiency. The purpose of this study is the investigation of fluid flow characteristics of oil jet and flow rate into the oil gallery.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.7
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• pp.879-888
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• 2003

Swirling air flow in a horizontal round tube was experimentally studied for its visualization. The present investigation deals with swirl angle, flow visualization studies and accompanying vortex core behavior by using oil smoke and a hot wire anemometer for Re = 40,000 and 50000 at X/D = 41, 59 and 71. In the swirl air flow, a vortex core was formed at high swirl intensity along the test tube. The swirl angle and the vortex core depended on the swirl intensity along the test tube. The results of swirl angles measured by flow visualization and hot wire reasonably agree with those of previous studies.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.218-224
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• 2006

Experimental results for pressure gradient of HCs refrigerants R-290. R-600a. R-1270 and HCFC refrigerant R-22 during condensing inside horizontal double pipe heat exchangers are presented. The test sections which have the tube inner diameter of 10.98mm. and the tube inner diameter of 8mm are used for this investigation. Hydrocarbon refrigerants have higher pressure drop than R-22 in both test sections with the diameters of 12.70mm and 9.52mm. Pressure drop increased with the increase of the mass flux. These results form the investigation can be used in the design of heat transfer exchanger using hydrocarbons as the refrigerant for the air-conditioning systems

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.549-556
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• 2002

An investigation on the fully developed heat transfer and friction factor characteristics has been made in rectangular ducts with one-side roughened by five different shapes. The effects of rib shape geometries as well as Reynolds numbers are examined. The rib height-to-duct hydraulic diameter, pitch-to-height ratio, and aspect ratio of channel width to height are fixed at e/De=0.0476, P/e=8, and W/H=2.33, respectively. To understand the characteristics of heat transfer enhancements, the friction factors are also measured. The data indicates that the triangular type rib has a substantially higher heat transfer performance than any other ones.

• Journal of Fisheries and Marine Sciences Education
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• v.23 no.1
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• pp.56-66
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• 2011

The purpose of this study is in analyzing factors related to a teacher's nursery efficacy. In order to achieve its purpose, a study includes investigation about levels of 748 teachers' interest and knowledge in a child nursery from multi-cultural families, teachers' efforts for understanding the children from multi-cultural families, availability of experience with a child care from multi-cultural families, a teacher's multi-cultural nursery efficacy and general nursery efficacy. As a result of investigation, a study found out that 4 factors (interest, knowledge, efforts, and experience) are related to nursery efficacy and the fact that a teacher's general nursery efficacy is highly associated with multi-cultural nursery efficacy. For this result, providing information about a child care from multi-cultural families and supporting general nursery efficacy play a critical role in supporting teachers' competency about a child care from multi-cultural families.

• Transactions of Materials Processing
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• v.20 no.3
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• pp.236-242
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• 2011

The two objectives of this study were, first, to determine the optimal friction welding process parameters using finite element simulations and, second, to evaluate the mechanical properties of the friction welded zone for large piston rods in marine diesel engines. Since the diameters of the rod and its connecting part are very different, the manufacturing costs using friction welding are reduced compared to those using the forging process of a single piece. Modeling is a generally accepted method to significantly reduce the number of experimental trials needed when determining the optimal parameters. Therefore, because friction welding depends on many process parameters such as axial force, initial rotational speed and energy, amount of upset and working time, finite element simulations were performed. Then, friction welding experiments were carried out with the optimal process parameter conditions resulting from the simulations. The base material used in this investigation was AISI 4140 with a rod outer diameter of 280 mm and an inner diameter of 160 mm. In this study, various investigation methods, including microstructure characterization, hardness measurements and tensile and fatigue testing, were conducted in order to evaluate the mechanical properties of the friction welded zone.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.2
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• pp.19-27
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• 2002

This paper deals with the experimental investigation on the hydrodynamic behavior of the submerged artificial seabed system in regular waves. This system can function as a basis of seaweed forest which will cultivate coastal fishing ground and enhance coastal productivity. The experiment was conducted with the submerged rectangular plates of different length and depth in 2-D wave flume of KRISO/KORDI. The wave exciting forces, mooring line tension and 2-D motion response are measured and analyzed to figure out the design strategy.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.5
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• pp.1211-1220
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• 2015

There exists dead zone from the aspects of health equity and health medical equity for maritime personnel. They could not have been benefited from disease prevention and health promotion in comparison with shore personnel due to the restricted medical accessibility caused by long voyage ship operation. Furthermore, the system of health management and medical assistance for maritime personnel is insufficient, the continuous health monitoring system does not exist, nor health diagnosis system, maritime industrial accidents and occupational disease control systems are adequate. The International Maritime Organization and the International Labour Organization recommend their Member Governments to take necessary measures in the management of seafarers' health and diseases through conducting continuous and systematic investigation. Thus, this study intends to propose action strategy and tasks for introducing marine telemedicine system aiming to provide seafarers with health management service for the years to come. The conclusions of this study can be given as follows. First, it is required that a systematic medical service system needs to be provided to promote seafarers' health. Second it is recommended to establish the marine telemedicine system incorporating U-Health technology. Third, it is necessary to revise the relevant laws and regulations to introduce the marine telemedicine system. Fourth, it is also necessary to provide various assistance system at the national level in the furtherance of global marketing of marine telemedicine system.

• Corrosion Science and Technology
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• v.14 no.5
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• pp.226-231
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• 2015

In spite of highly advanced paint coating techniques, corrosion damage of marine metal and alloys increase more and more due to inherent micro-cracks and porosities in coatings formed during the coating process. Furthermore, flowing seawater conditions promote the breakdown of the protective oxide of the materials introducing more oxygen into marine environments, leading to the acceleration of corrosion. Various corrosion protection methods are available to prevent steel from marine corrosion. Cathodic protection is one of the useful corrosion protection methods by which the potential of the corroded metal is intentionally lowered to an immune state having the advantage of providing additional protection barriers to steel exposed to aqueous corrosion or soil corrosion, in addition to the coating. In the present investigation, the effect of flow velocity was examined for the determination of the optimum corrosion protection current density in cathodic protection as well as the corrosion rate of the steel. It is demonstrated from the result that the material corrosion under dynamic flowing conditions seems more prone to corrosion than under static conditions.

• ALGAE
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• v.37 no.3
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• pp.239-247
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• 2022

Enzyme-assisted hydrolysis is frequently used as a cost-effective and efficient method to obtain functional ingredients from bioresources. This study involved the enzyme-assisted hydrolyzation and purification of fucoidan from Ecklonia maxima stipe and the investigation of its anti-inflammatory activity in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Fucoidans of Viscozyme-assisted hydrolysate from E. maxima (EMSFs) harvested in Jeju, Korea. Structural and chemical characterizations were performed using fourier transform infrared spectroscopy, scanning electron microscope, and monosaccharide analysis. Among fucoidans, EMSF6 was rich in fucose and sulfate and had a similar structural character to commercial fucoidan. EMSF6 showed a strong inhibitory effect on nitric oxide generation in LPS-induced RAW 264.7 cells and significantly decreased the production of LPS-induced pro-inflammatory cytokines, including interleukin-6, interleukin-1β, and tumor necrosis factor α. The anti-inflammatory potential of EMSF6 was mediated through the downregulation of inducible nitric oxide synthase and cyclooxygenase-2 expression. Thus, fucoidans from E. maxima stipe are promising candidates for functional food products.