• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.63-68
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• 2005

In this paper, 6-DOF motion equations of UUV (Unmanned Undersea Vehicles) are derived Moreover, the hydrodynamic maneuvering derivatives are found from the oblique towing tests of the 2m Manta type UUV model.

• Journal of Ship and Ocean Technology
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• v.8 no.3
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• pp.1-7
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• 2004

The current paper deals with the safety of fishing vessels, which needs more speculations than other ship types. The characteristics of accidents of fishing vessels are rather different compared with other commercial vessels. In the context, the methodology of the formal safety assessment, one of the important issues in the maritime world to enhance the safety of marine vehicles, are reviewed and consulted along with other methodologies to see its applicability for fishing vessels. It is anticipated that further effective measures for better safety of fishing vessels can be identified including due considerations of the aspect of human elements, i.e. cultural environment.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.216-221
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• 2017

Diesel engines have the highest brake thermal efficiency among internal combustion engines. Therefore, they are utilized in medium and large transportation vehicles requiring large amounts of power such as heavy trucks, ships, power generation systems, etc. However, diesel engines have a disadvantage of generating large quantities of nitrogen oxides during the combustion process. Therefore, the authors tried to reduce the amount of nitrogen oxides in marine diesel engines using a wet-type exhaust gas cleaning system utilizing the undivided electrolyzed seawater method. In this method, electrolyzed seawater in injected into the harmful gas discharge from the diesel engine using real seawater. The authors investigated the reduction of NO and NOx from the pH value, available chlorine concentration, and the temperature of electrolyzed seawater. The results of this experiment indicated that when the electrolyzed seawater is acidic, the NO oxidation rate in the oxidation tower is higher than that when the electrolyzed seawater has a neutral pH. Likewise, the NO oxidation rate increased with the increase in concentration of chlorine. Further, it was confirmed that the electrolyzed seawater temperature had no effect on the NO oxidation rate. Thus, the NOx exhaust emission value produced by the diesel engine was reduced by means of electrolyzed seawater treatment.

• The Journal of Fisheries Business Administration
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• v.34 no.2
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• pp.91-107
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• 2003

Distribution of fish products from Tongyoung Marine ranching can be classified by three routes such as street-stall, live fish transportation vehicles, and wholesale markets neighboring unloading ports. These methods of distribution, however, have been restricted by limited distribution right, difficulties to differentiate fish prices from other surfaces, simple marketing channels. The ratio of cultured live fish circulated in market is increasing while naturally caught live fish is decreasing and the fresh fish shows a little of increasing rate. Consumers purchasing routes mainly depend on the live fish transportation merchants. For fresh fish traditional market plays an important role in trade. Convenience for consumers and quality of products are main factors in making decision of purchases. Bargaining power, however, belongs to the live fish transportation merchants. The demand of special markets for live fish was very strong, and the convenience and quality are relatively important required factors. Catch from Tongyoung Marine ranching has very good reputation as the possibility of being a good brand. Expecting possibility of quality differentiation was higher than price differentiation specially. The possible conclusion of a contract of a supply was suspicious however. Preliminary quality evaluation revealed that the catch is better than the cultured but worse than naturally grown fish. A merchandising is to be in a better position in the formation of prices by giving $\ulcorner$brand image$\lrcorner$ to potential consumers. The target markets are retail stores such as restaurants for raw fish and final consumers. The staple markets are retail stores. Possible items of products are live fish, fresh fish for cook, and fresh fish for raw fish. It is necessary for the catch to be informed as new functional products that have been improved in safety and quality, since the product positioning is similar but not well known to consumers. To secure a brand it is required to register a trademark, eco-label product design or packing, use real name in tranction, introduce recall system, and put label. Price higher than naturally grown live fish should be targeted. Establishing broad distribution channel, wholesale market, franchise are required. To secure enough catch and control shipment of products facilities of containing live fish are necessary. Instead of dealing with live fish only, it would be better to. sell fresh fish and live fish simultaneous. Strategically promotion focuses on advertisement of Marin ranching at first and then focuses on the catch from the marine ranching.

• Fisheries and Aquatic Sciences
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• v.22 no.11
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• pp.26.1-26.7
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• 2019

Background: The monitoring of pathogens of fishery auction markets is important to obtain safe fishery products regarding hygiene and sanitation. In this study, aerobic, coliform, Escherichia coli, and Vibrio cholerae were monitored in the fishery products and environmental samples obtained from fishery auction markets. Methods: The fishery products (flounder, octopus, skate, rock cod, sea bass, snail, monkfish, flatfish, comb pen shell, corb shell, conger eel, hairtail, croaker, and pilchard) were placed in filter bags, and the environmental samples (samples from the water tanks at the fishery auction markets, seawater from the fishery distribution vehicles, ice from wooden or plastic boxes, and surface samples from wooden and plastic boxes used for fish storage) were collected. Aerobic bacteria, E. coli, and coliform in the samples were enumerated on aerobic count plates and E. coli/coliform count plates, respectively. For V. cholerae O1 and V. cholerae non-O1 quantification, most probable number (MPN)-PCR analysis was performed. Results: Aerobic and coliform bacteria were detected in most samples, but E. coli was not detected. Wooden boxes were contaminated with high levels of aerobic and coliform bacteria in all seasons (spring, summer, and fall). During fall, V. cholerae non-O1 were detected in snails, hairtails, croakers, flatfishes, pilchards, plastic boxes, and water samples. Conclusions: These results indicate an increased prevalence of V. cholerae contamination in fishery products in fall, including food contact samples, which can be vehicles for cross-contamination.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.509-521
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• 2020

This study aims to propose a mid- to long-term fostering plan for the hydrogen industry customized to Changwon City by reviewing the government's policy and the status of the domestic and foreign hydrogen industry. The adopted methodologies were policy analysis, literature review, field investigation, and committee operation that could consider institutions, knowledge (technology), and networking between activity subjects. The short-term projects and long-term projects for the fostering plan are established using these methodologies. The short-term projects were structured so that the ongoing hydrogen industry fostering plan leads to a successful result, and the hydrogen mobility field is expanded to not only land vehicles but also marine and air vehicles. The long-term projects consist of a high proportion of the hydrogen utilization field to take advantage of the industrial strength of Changwon City, and a support system for new and turning companies for localization of parts was added to provide industrial competitiveness.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.892-901
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• 2020

We used a numerical method to estimate the hydrodynamic maneuvering derivatives for the heave-pitch coupling motion of an underwater glider. It is very important to assess the hydrodynamic maneuvering characteristics of a specific hull form of an underwater glider in the initial design stages. Although model tests are the best way to obtain the derivatives, numerical methods such as the Reynolds-averaged Navier-Stokes (RANS) method are used to save time and cost. The RANS method is widely used to estimate the maneuvering performance of surface-piercing marine vehicles, such as tankers and container ships. However, it is rarely applied to evaluate the maneuvering performance of underwater vehicles such as gliders. This paper presents numerical studies for typical experiments such as static drift and Planar Motion Mechanism (PMM) to estimate the hydrodynamic maneuvering derivatives for a Ray-type Underwater Glider (RUG). A validation study was first performed on a manta-type Unmanned Undersea Vehicle (UUV), and the Computational Fluid Dynamics (CFD) results were compared with a model test that was conducted at the Circular Water Channel (CWC) in Korea Maritime and Ocean University. Two different RANS solvers were used (Star-CCM+ and OpenFOAM), and the results were compared. The RUG's derivatives with both static drift and dynamic PMM (pure heave and pure pitch) are presented.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.1-7
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• 2020

In recent years, cargo lashing has received much importance, to help prevent the sinking of passenger ships due to the failure of vehicle and cargo lashing during the transshipment of cargo. Consequently, the standards for lashing equipment and the structure of car ferries have been revised. According to the current standards, all vehicles loaded on a car ferry sailing in smooth sea areas must be secured if the wind speed and wave height exceed 7 m/s and 1.5 m, respectively. In this study, we measured the roll and pitch of a passenger ship sailing in smooth sea areas, and compared the measurements with the results of the New Strip Method (NSM). The vessel had a maximum pitch of 1.41° and a maximum roll of 1.37° at a wind speed of 6-8 m/s and a wave height of 0.5-1.0 m, and a maximum pitch of 1.49° and a maximum roll of 2.43° at a wind speed of 10-12 m/s and a wave height of 1.0-1.5 m. A comparison of the external forces due to the motion of the hull and the bearing capacity without lashing indicated that the bearing capacity was stronger. This suggests that vehicles without lashing will not slip or fall due to weather conditions. In future, the existing vehicle lashing standards can be revised after measuring the hull motions of various ships, and comparing the external force and bearing capacity, to establish more reasonable requirements.

• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.80-87
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• 2011

Autonomous underwater vehicles (AUVs) present the important advantage of being able to approach the seafloor more closely than surface vessel surveys can. To collect bathymetric data, bottom material information, and sub-surface images, multibeam echosounder, sidescan sonar (SSS) and subbottom profiler (SBP) equipment mounted on an AUV are powerful tools. The 3000m class AUV URASHIMA was developed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). After finishing the engineering development and examination phase of a fuel-cell system used for the vehicle's power supply system, a renovated lithium-ion battery power system was installed in URASHIMA. The AUV was redeployed from its prior engineering tasks to scientific use. Various scientific instruments were loaded on the vehicle, and experimental dives for science-oriented missions conducted from 2006. During the experimental cruise of 2007, high-resolution acoustic images were obtained by SSS and SBP on the URASHIMA around the northern Kumano Basin off Japan's Kii Peninsula. The map of backscatter intensity data revealed many debris objects, and SBP images revealed the subsurface structure around the north-eastern end of our study area. These features suggest a structure related to the formation of the latest submarine fan. However, a strong reflection layer exists below ~20 ms below the seafloor in the south-western area, which we interpret as a denudation feature, now covered with younger surface sediments. We continue to improve the vehicle's performance, and expect that many fruitful results will be obtained using URASHIMA.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.7
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• pp.931-941
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• 2020

There is a growing interest this paper for ocean sensing where autonomous vehicles can play an essential role in assisting engineers, researchers, and scientists with environmental monitoring and collecting oceanographic data. This study was conducted to develop a rigid sail for the autonomous sailing drone. Our study aims to numerically analyze the aerodynamic characteristics of curvy twin sail and compare it with wing sail. Because racing regulations limit the sail shape, only the two-dimensional geometry (2D) was open for an optimization. Therefore, the first objective was to identify the aerodynamic performance of such curvy twin sails. The secondary objective was to estimate the effect of the sail's spacing and shapes. A viscous Navier-Stokes flow solver was used for the numerical aerodynamic analysis. The 2D aerodynamic investigation is a preliminary evaluation. The results indicated that the curvy twin sail designs have improved lift, drag, and driving force coefficient compared to the wing sails. The spacing between the port and starboard sails of curvy twin sail was an important parameter. The spacing is 0.035 L, 0.07 L, and 0.14 L shows the lift coefficient reduction because of dramatically stall effect, while flow separation is improved with spacing is 0.21 L, 0.28 L, and 0.35 L. Significantly, the spacing 0.28 L shows the maximum high pressure at the lower area and the small low pressure area at leading edges. Therefore, the highest lift was generated.