• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.614-621
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• 2007

The fishing boat propulsion system employing the modified stern shape and the tunnel to protect a propeller is developed to increase the cruise speed and reduce he problem resulting from the open propeller accidentally catching the waste net and able on the sea. Using 3 different tunnel types, the model test was performed in the circular water channel and the panel method based on the potential theory is applied to analyze the open water performance of the propeller. In the numerical analysis using he potential-based panel method, it calculates the hydrodynamic interaction between the propeller and the tunnel and evaluates the effect of the tunnel geometry. From the numerical and experimental results differing tunnel geometries, the propulsion efficiency is increased by the larger diameter of the inlet than the outlet of the tunnel and the smaller gap between the propeller tip and the tunnel internal surface. These results provide the information of the propeller system with the tunnel and the hydrodynamic interaction between the propeller and the tunnel.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.1 s.145
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• pp.119-127
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• 2006

Recently as a result of excessive development. pollution of the coast and occurrence of a typhoon year after year, fishermen suffer heavy losses in fish farming which is the one of the most important earnings ways. For solution of these problems, we need to go out into the open sea from an inland sea. In this study we suggested new fish cage which makes up for the structural weakness of existing wooden fish cages. It can farm fishes in the open sea of high wave and current with no damages from a typhoon. We substituted TPU(Thermoplastic Polyurethane) air chamber for existing styrofoam flotage which was harmful to the environment and impermanent. We used PE(Polyethylene) pipes for the maintenance of formation and the prevention of buoyancy loss caused by a breakdown of flotage. PE b rackets were designed to combine PE pipes with TPU air-chamber flotage. It has good strength and light weight. As a result of modeling test. it is great in buoyancy, strength and flexibility against wave. Because it can control buoyancy arbitrarily, moreover, we expect that it will reduce damages of a red water by applying it as semi-submerged fish cages.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.6
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• pp.497-504
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• 2018

Platform Support Vessels operated in the Arctic Ocean support diverse operations of offshore plant in the sea, and the PSV is also needed to support works to exploit the oil and gas in the Arctic Ocean. Both of the ice breaking and the open sea performance have been considered together to secure the enhanced operational performance at the harsh environment in the Arctic Ocean and the open sea as well. In this study, One of the design requirements of a PSV is to guarantee continuous icebreaking performance with 3 knots at 1 m thickness of level ice, where the design draft is 7.5m and the engine power is 13 MW. Three hull forms were designed, and the ice resistance based on empirical formulas was estimated to select the initial hull form having an outstanding performance. The full scale performance of the designed hull forms was predicted by the ice model test conducted in the ice model basin of Korea Research Institute of Ships & Ocean Engineering(KRISO). The analysed results show that the selected hull form satisfies the above design requirement.

• Journal of the Korean Institute of Navigation
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• v.21 no.2
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• pp.11-17
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• 1997

In this paper, we studied to improve Inoue's[1] and Kijima's[2] model used to predict ship's manoeuvrability in initial design stage. To perform this work, we had PMM(Planar Motion Mechanism) test and rudder open water test for 12 Models of low-speed blunt-ship which have horn type rudder and bulb in afterbody. Using MMG(Mathematical Modelling Group) model, we analyzed hydrodynamic and MMG experimetnal coefficidnts used to search sensitivities and to estimate ship's manoeuvrability, adn the results are performed by the regression analysis of principle parameters. We varified them to analyze ship's manoeubbrability , had simulate manoeubrability to check revised MMG model and compared them wiht Inoue's method. the result of PMM test and sea trial. Then it is found that the revised method can predict the maneuverability more accurately even for an unstable ship.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.87-95
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• 2006

The performance of a microwave missile seeker and radar operating in an air-to-air look-down mode is strongly influenced by the presence of ground clutter In order to correctly account for the effects of ground clutter, it is required to develop a model capable of representing clutter characteristics as a function of range and/or frequency. In this paper, a program to estimate the clutter reflectivity for various ground conditions is developed, using the actually measured data and the data available from open literatures. In addition, clutter characteristics measured for various ground conditions such as sea, agricultural area, urban city and industrial area through the captive flight tests are presented.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.10-18
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• 2022

This study analyzed the relationship between the community structure of benthic macroinvertebrates and habitat changes in open estuaries among the sites included in the national estuary monitoring program. The estuary survey was conducted under the "Guidelines for Investigation and Evaluation of Biometric Networks" and classified by sea area, 80 places in the East Sea, 102 places in the South Sea, and 19 places in the West Sea were investigated. In a total of 201 open estuaries, benthic macroinvertebrates were identified with 4 phyla, 9 classes, 41 orders, 139 families, 269 species and 196 species in the East Sea, 182 species in the South Sea, and 90 species in the West Sea. The highest population densities were Insecta in the East Sea, the Malacostraca in the South Sea, and the Annelida in the West Sea. Through SIMPER analysis, species contributing to the similarity of benthic macroinvertebrates communities in each sea area were identified. Some species greatly influenced the similarity of clusters. The benthic community in the East Sea was affected by the salinity, so the contribution rate of freshwater species was high. On the other hand, the benthic communities of the South and West Seas showed species compositions are influenced by the substrate composition. As results, the benthic macroinvertebrate community in Korean estuaries was impacted by salinity and substrate simultaneously, and the close relationship with geographical distance was not observed. The result of this study is expected to be used to respond to environmental changes by identifying and predicting changes in the diversity and distribution of benthic macroinvertebrates in Korea estuaries.

• The Transactions of the Korea Information Processing Society
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• v.3 no.5
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• pp.1027-1036
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• 1996

X.500 Directory is an application level protocol in the Open Systems Interconnection(OSI) 7 layer's reference model adopted by the international Standards Organization (ISO). It manages effectively needed information for the communication service, and is a service to support the functions that the user can approach conveniently. Tourist information is distribution on several locations. The access of distributed information is similar to X.500 directory service. Therefore, we design of Tourist Information System(TIS) and directory schema using X.500 directory services. To define tourist information, we also propose Directory Information Tree(DIT) of locality architecture and several new object classes, such as museum, mountain, sea, hotel, etc.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.2
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• pp.176-184
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• 2014

Nowadays, consumption of fisheries products is increasing. There are several factors, one of which is a quantitative development through aquaculture. Another factor is an increase qualitative consumption of fish which require that fish be supplied alive. This requires a lot of technical effort to transport the live fish that have low survival rate (c.f. tuna and mackerel) in coastal waters and in the open sea. To develop a towing cage for transporting the live fish, model test in a circulate water channel and simulation by computer tool were carried out. In order to spread vertically, floats were attached at the upper part of the cage, and iron chains attached at the lower part of the cage. For horizontal spreading, kites were attached on the cage. The tension and spreading performance of the cage were measured. The result shows that the tension and reduction ratio of inside volume of the cage were tended to increase with increased towing speeds. The suitable operation condition in towing cage was 1.0 m/s towing speeds with vertical spreading force 8.7 kN, horizontal spreading force 5.6 kN; in this case the reduction ratio of inside volume of the cage was estimated as 25%.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.165-180
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• 1999

Static load tests were performed for open-ended piles, closed-ended piles, piles with grouted toe, and base-grouted piles by using calibration chamber. Then vertical bearing capacities determined from load tests were compared with each other. The stability of base-grouted pile during a simulated seaquake was investigated by changing the penetration depth. Also, static load tests and seaquake tests for 2-piles and 4-piles group were performed. The bearing capacity of the pile grouted inside the toe was 11.2~30.8% less than that of open-ended pile because of reduction of base resistance due to disturbance of base soil under pile toe. The bearing capacity of a base-grouted pile was 23.8~33.9% more than that of an open-ended pile and was similar to that of a closed-ended pile. The bearing capacity of base-grouted group pile was increased ; the bearing capacity of base-grouted 2-piles group increased 14.6~31.8% compared to that of open-ended 2-piles group, and that of base-grouted 4-piles group increased 15.3~22.4% compared to that of open-ended 4-piles group. During the simulated seaquake in deep sea, stability of base-grouted pile was found to be dependent on the pile penetration depth. During seaquake motion, single long base-grouted pile longer than 20m was stable and short base-grouted pile shorter than 12m failed. But relatively long base-grouted pile longer than 12m kept mobility state. Bearing capacity of base-grouted group pile with penetration depth less than 7m was degraded a little bit ; so, base-grouted group pile could maintain mobility condition.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2007.12a
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• pp.141-142
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• 2007

In recent years, the rate of mean sea level rise is increasing rapidly from the phenomena of global warming, together with the increasing trend of the storm scale. The issue of sea level rise is multifaceted and produces a range of environmental problems. Especially, high tides and the tidal currents become higher, and wave base increases, so the energy received at the coastal boundary may increase. This brings that many coastal environments go into disequilibrium, such as damages to the structures, erosion, and deposition Similarly it was known that the problems of nearshore processes and damage of berth and counter facilities during storm period had appeared at the small fishery port. Here we try to analyze the impact of the rearrangement of counter facilities and berth layout adopted for tranquility of its'inner harbor. Because this harbor is being connected to channel and open sea, the rearrangement of the structures might affect to the current speed and direction and wave height, so do to the sea bottom undulation. Therefore, we made model test for the several layouts of the berth and breakwater in this area.