• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.68-77
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• 2018

In order to analyze the overall characteristics of the lunar orbiter, the Variable Coast method, which can be launched everyday, is applied to the 3.5 phasing loop transfer trajectory. The mission scenario for the entire process from launching to entering the lunar orbit is set up and performed simulation by selecting the launch pad and launch vehicle. In particular, the SEM(Satellite-Earth-Moon) angle defined in Earth-Moon rotating frame is an important constraint to comprehensively evaluate the 3.5 phasing loop transfer trajectory. The simulation using SEM angle is analyzed from various viewpoints such as launch epoch, coast duration, perigee altitude and ${\Delta}V$ not only trans-lunar trajectory but lunar orbit insertions and the optimum SEM angle is suggested in this study. It is expected that this results will be helpful to evaluate the characteristics of the 3.5 phasing loop transfer trajectory according to the launch vehicle selection by comparison with Fixed Coast analysis results in the future.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1170-1180
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• 2009

Recently this country has carried out the coast reclamation centering on the west and south coast for effective practical use of a country, considering purchase of materials and environmental problem, most reclaiming work is processing to spoil reclamation which is easy to secure the amount of materials. In case of weak ground that is formed by spoil reclamation like this, initial moisture content is high, as slurry state that is rarely revealed ground strength, compressibility and water permeability have been shown nonlinear change by compaction progress. Analysis of weak ground is unreasonable because the existing Terzaghi compaction theory analyzes compaction fixed number to regular invariable number for prediction of compaction state. This study computes the relation with void ratio-effective pressure and void ratio-finite transformation which is the most basic matter to predict finite strain compaction state of the south coast spoil, and analyze the basic feature to predict compaction feature of the south coast spoil reclaimed ground.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.282-287
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• 2018

Due to limitations in responding to oil spill incidents that are urgent or that cover a wide area with only oil spill response vessels, Korea Coast Guard (KCG) patrol vessels are utilized. In this study, we have developed an oil sweep system suitable for small patrol vessels. The equipment consists of three components - fixed support, poles, and slide fixers - and can be fastened with a toggle pin to a fall prevention bar on small patrol vessels without welding or additional efforts for installation. The respective weights of each component - fixed support, poles (2 pcs), and slide fixers (4 pcs) - are approximately 9.2 kg, 6.5 kg, and 3.5 kg. The 3 m-pole, which is rotatable 180 degrees horizontally, is folded deckward when replacing oil absorbents. As the development of this equipment has improved the method of deploying and retrieving oil absorbents on KCG small patrol vessels, we expect that more efficient oil spill cleanup will be possible.

• Animal Systematics, Evolution and Diversity
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• v.31 no.4
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• pp.284-295
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• 2015

Two new species of Leptochelia Dana, 1849 are described from the western coast of Korea. Leptochelia grandidentata n. sp. is similar to L. itoi and L. lusei characterized by pleonites 4 and 5 of subequal lengths and a uropod endopod with 4 articles but differentiated by a cheliped fixed finger longer than the dactylus and with 4 teeth along the incisive margin, a maxilliped basis with 4 distal setae, and pereopod 1 propodus that is much longer than the combined length of unguis and dactylus. Leptochelia suhi n. sp. shares some features of L. myora with the first article of the uropod endopod longer than the second article and a maxilliped endite with 3 spiniform distal setae but can be differentiated by the cephalothorax being longer than the pleon, the relatively longer antennule article 3 compared to article 2, and the cheliped fixed finger with 3 robust teeth along the incisive margin. In this study, full descriptions of L. grandidentata and L. suhi are given, and a comparison with closely related species belonging to the ‘dubia/savignyi group’ is tabulated and discussed.

• 한국해양학회지
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• v.19 no.1
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• pp.24-30
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• 1984

A numerical experiment was carried out on thee wind-induced coastal upwelling along the east coast of Korea. Only the variability in coastline geometry is considered and an attempt is made to correlate it with the observation previously performed. In order to approximate the coastline geometry as closely as possible, the finite element method with linear triangular grid is employed. Among several fixed locations of upwelling center found in the model, the one in the southeastern coastal area seems to be just what has been observed most frequently.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.5 no.1
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• pp.13-22
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• 1987

The position fixing is the first essential in any offshore activity. At sea, position is almost always related to fixed points on land. The traditional method of the position fixing of a vessel is by double horizontal sextant angles observed between three fixed stations, plotted as a graphical resection using station pointers. Of recent, offshore fixing progresses in simple object of navigation and fishery, and it is tending to use and develop ocean and coast compositly. Therefore, we compared and analyzed deviation of fixed point for more accurate offshore fixing. This paper used only navigation instruments such as NNSS, Loran-C, Omega involved in long range and world wide among the methods of E. P. F. (Electromagnetic Position Fixing).

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.421-428
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• 2011

We conducted modeling experiments to evaluate the residence times and exchange rates of seawater in Gamak Bay, located on the southern coast of the Korean Peninsula. The results revealed that pollutants are more quickly dispersed in a fixed grid rather than in a variable grid system. Pollutant concentrations decayed exponentially with time after release near the mouth of the bay, whereas no exponential variations were seen at the northwest end of the bay. The mean exchange rate of the seawater was 1.58% per day in the variable grid system, and the residence time of pollutants was greater than 288 days in Gamak Bay. Conversely, the exchange rate of seawater in Gamak Bay, as revealed by the particle tracking method, was 65% over a 50-day simulation. The results suggest that the seawater exchange in Gamak Bay is so low that pollutants are likely to remain in the bay indefinitely.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.1
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• pp.78-87
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• 2014

Recently the offshore wind turbine development is requested to be installed off south-west coast and Jeju island in Korea. Reliable and robust support structures are required to meet the demand on the offshore wind turbine in harsh and rapidly varying environmental conditions. Monopile is the most preferred substructure in shallow water with long term experiences from the offshore gas and oil industries. This paper presents an optimum design of a monopile connection with grouted transition piece (TP) for the reliable and cost-effective design purposes. First, design loads are simulated for a 5 MW offshore wind turbine in site conditions off the southwest coast of Korea. Second, sensitivity analysis is performed to investigate the design sensitivity of geometry and material parameters of monopile connection based on the ultimate and fatigue capacities according to DNV standards. Next, optimization is conducted to minimize the total mass and resulted in 30% weight reduction and the optimum geometry and material properties of the monopile substructure of the fixed offshore wind turbine.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.103-113
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• 1996

Two-dimensional finite element hydrodynamic models for long wave simulation usually adopt fixed land boundary. However moving boundary treatment is strongly required in the simulation of tidal flats for west and south coast of Korea. In this study very efficient and realistic moving boundary treatment is applied by considering incident long wave surface slope. Developed STEP-CM (Superior Two-step Explicit Program for Coastal Modeling) ,shows numerically stable results in comparative study for idealized one-dimensional channel. Real application of the model is done for Chonsu Bay where tidal flats are distributed along the coast. Nonlinear tidal current and tidal flat effects are easily simulated in STEP-CM and resulting circulations are detected around headland of Wonsan Island.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.621-628
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• 2013

It is already recognized, the fleet crew of Korean Coast Guard(KCG) have come to perform a wide range of roles that they carry on duties on inferior working conditions. Therefore a research on leadership is seemed necessary to improve organizational effectiveness for them. This study is to examine whether leadership style with transformation is appropriate in organizational commitment for the fleet crew of KCG. In this study transformational leadership is fixed as independent variables and organizational commitment as dependent variables and also five factors as demographic characteristics. Intellectual stimulation is turned out to be the most influential factor in organizational objective(t=6.664, p=0.000) and continuance commitment(t=4.057, p=0.000), but individualized consideration are uninfluential factors concerning organizational commitment.