• Korean Journal of Ichthyology
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• v.21 no.4
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• pp.262-272
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• 2009

Upstream behavior of glass eels was examined in an experimental eel-ladder at a laboratory of the National Fisheries Research and Development Institute from March to May in 2008. The study was made under various environmental factors and conditions affecting the upstream migration of glass eels in order to design a functional ladder that would allow the passage of glass eels. The experimental eel-ladder consisted of an upper freshwater chamber and a lower sea water chamber; glass eels in sea water can move up to the upper freshwater chamber through the slope (eel-ladder) between them. The optimal condition of the eel-ladder was estimated by comparing the number of glass eels that moved upstream depending on various conditions. Since the glass eels actively moved up the slope to river water rather than to reservoir water or tap water, the experiment was realized using river water. A significantly higher number of glass eels moved up during the spring tide than during the neap tide, and during night than during the day. Upstream movement was significantly higher during high tide than during low tide. Glass eels effectively moved up through a slope of less than $30^{\circ}$ and water-flow velocity lower than 0.4 m/sec. The fish preferred a coarser ladder bed covered with small gravels, brush or carpet.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.21-28
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• 2012

The combined effects of water temperature and salinity on the settlement rate and density (spats/$cm^2$) of Crassostrea gigas pediveliger larvae were studied under the hatchery conditions. Four water temperatures (20.0, 23.0, 26.0 and $29.0^{\circ}C$) were tested at three salinities (20.0, 30.0 and 40.0). The optimum water temperature by salinity conditions were $29.0^{\circ}C$ and 20.0, 30.0 which significantly (P < 0.05) the highest mean (${\pm}S.D$) larval settlement rate of $43.1{\pm}0.1%$, $42.1{\pm}0.1%$, respectively. But the combination of water temperatures and salinities for settlement density was not effected, but each factor as water temperature ($29.0^{\circ}C$), salinity (40.0) was shown significantly high and low settlement density, respectively (P < 0.05). The statistics result of settlement density frequency was appeared: mode ($1.2-2.3spats/cm^2$), Mean ($1.9-2.4spats/cm^2$), Range ($3.0-5.8spats/cm^2$) and the lowest variance was obtained 0.4 at water temperature $20.0^{\circ}C$ by salinity 30.0, but $29.0^{\circ}C$ by 20.0 was the highest (1.1). The best condition at this results for the larvae setting under the artificial seed collection of C. gigas was $29.0^{\circ}C$ and 20.0-30.0.

• Journal of Korea Water Resources Association
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• v.30 no.6
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• pp.761-768
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• 1997

A numerical model is developed to analyze the incompressible unsteady flow induced by the pump trip-out in the cooling water discharge culvert of thermal power plants. The numerical models has various features to deal concureently with the overall behavior of complicated unsteady flow due to the presence of cooling water internal system, seal well, air chamber, culvert, manholes, open channel and sea water. A leap-frog finite difference scheme is employed to solve governing equations, and the model is tested for a simple case of two tanks connected with a pipe. A fixed free surface boundary condition used earlier at the downstream end of culvert for large water body is investigated.

• Journal of Environmental Science International
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• v.15 no.7
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• pp.623-634
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• 2006

In this study, characteristics of fog at Mokpo as the west coastal area of Jeonnam were investigated, using statistical analysis of observed fog and meteorological data. Higher frequency of the fog occurrence at Mokpo was showed in spring(32%) and summer(34%) due to the seasonal high atmospheric pressure. Regional characteristics as radiation cooling, advection of fog and water vapor from surrounding sea and Yeongsan lake, and frontal fog had major effect on the coastal fog at Mokpo on the meteorological conditions of north-west/south wind and calm($0{\sim}2m/s$). Also, as the results of analyzing data of before and after the construction of Yeongsan dam, the frequency of annual mean fog days increased 41 %, specially increased 178% in autumn. The increase of fog days mainly resulted from evaporation during colder seasons and from temperature inversion during warmer seasons over the water surface of Yeongsan lake. The construction of Yeongsan dam had a little effect on the meteorological conditions concerning fog occurrence, because Yeongsan dam which only supplies the water for use do not always carry out outlet of the cold water. In addition, the sea fog at Heuksando located in offshore had not effect on the occurrence of fog at Mokpo.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.299-307
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• 2016

This study aims to investigate effects of the length of the buoy and sand bag line on the loss of webfoot octopus pot. A numerical modeling and simulation was carried out to analyze the process that the pot gear affected by wave using the mass spring model. Through the simulation, tensions of sand bag line under various condition were investigated by length of buoy and sand bag line. The drag force and coefficient k of an artificial shell used in the webfoot octopus pot was obtained from an experiment in a circular water channel, and the coefficient k was applied to the simulation. To verify the accuracy of the simulation model, a simple test was conducted into measuring a rope tension of a hanging shell under flow. Then, the test result was compared with the simulation. The lengths of the buoy line in the simulation were 1.12, 1.41, 1.80, 2.23, 2.69, and 3.17 times of water depth. The lengths of sand bag line were 10, 20, 30, and 40 meters, and conditions of water depth were 8, 15, 22 meters. 4 meter height and 8 second period of wave were applied to all simulations. As a results, the tension of the sand bag line was decreased as the buoy and sand bag line were increased. The minimum tension of the sand bag line was appeared in conditions that the length of the buoy line is twice of water depth and the sand bag line length is over 40 meters (except in case of depth 8 meters.).

• Journal of Fisheries and Marine Sciences Education
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• v.11 no.1
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• pp.24-42
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• 1999

I have studied historical transition process of fisheries industries, fisheries Institute in abreast of developing fisheries industries of west coast of Korea since 1910 year with regard to the Gogunsan Is. The results were summarized as follows. In 1910 year, fishery industry has been carried out shifting fishing gear e.g set-net in shallow waters, small stow net, small seine net adapting to the tophorgrapical feature, shape of coast, oceanic condition, however, the fishing gear and fishing method were undeveloped, so that, Japanese fishermen had been exploited fisheries resources penetrating the fishing ground. Most important species were lot of captured croaker, cod, spanish mackeral, sea abream, herring in coastal sea. nowaday, squid, anchovy, shrimp, crab, pompret were much captured. The species were captured in 18 century were not captured. It is rarely than that period. Fishereis aquatic culture had been not farmed till 1960 year, but sea laver, shrimp, crab, had been breeded 1970 year also, the fresh water fish e.g. eel, cat-fish had been breeded activately. The fisheries processing industry were composed of salt. icing, dry, method. the salted fish industry had been prevailed at Gangyng, Kwangchon, Kunsan, Julpo comparatively. The fisheries institute had been established at Kunsan at first, but institute established in other region had been abolished in a short time. This phenomenon was related with development of fisheries resources. The western coast fisheries industries had been wasted of decreasing of fisheries resources, variation of environment. Accordingly, the study of preserving the marine resources. educated man power who engaged in fisheries field have to accomplish. Sea was dying with reason of loss of mud in west coast factory waste, waste of life the increase of accident of sea polluted, each illegal fishing industry physical and chemical reason etc. in this respect, Kusan maritime college, fisheries developing agency, institute have to take important role for developing fishing industry.

• Journal of Surface Science and Engineering
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• v.45 no.6
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• pp.278-283
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• 2012

This investigation evaluated the effect of cavitation condition on electrochemical characteristics of 304 stainless steel, which is widely used for marine environment. The cavitation test with time were conducted on 304 stainless steel in seawater solution. Surface morphologies of specimen were observed by scanning electron microscope (SEM) and 3D microscope. Pitting depth, weight loss and damage rate were analyzed after each cavitation experiment. The surface damage was more severe as the current density increased. A dramatical increase in the damage depth and weight loss was observed after 7 hours of cavitation experiment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1726-1734
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• 2004

Response surface methodology on sensory evaluation was used to optimize cooking condition of cooked short grain rice (CSR) and cooked short grain rice containing grainy sea-tangle patch (CSTR). Texture profile analysis and nutritional evaluation were also performed. For maximizing overall acceptability, it can be predicted sea-tangle patch 14%, added water 1.67 times of rice and sea-tangle amount and steeping time 47 min as optimum cooking conditions from sensory evaluation conducted by the forties panelist. Hardness of pressure cooked short grain rice containing grainy sea-tangle patch (CSTR) were lower than cooked short grain rice (CSR), but it showed similar as CSR in adhesiveness, chewiness and higher in springiness and cohesiveness. In addition CSTR was delayed retrogradation compared with CSR. The nutritional Quality of CSTR showed higher level in total dietary fiber, protein, ash than CSR, but lower in protein digestibility, C-PER, gelatinization degree compared with CSR.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.12
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• pp.1089-1096
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• 2015

A marine helicopter should remain sufficiently upright to permit safe evacuation of all personnel with a flotation system. And the rule requires that after ditching in water, the adequate flotation time will allow the occupants to leave the rotorcraft. To this end, stability test of the emergency flotation system for Korean marine helicopter was performed by using "Froude scaling method" in water tank. Test configuration and conditions were determined in consideration of the helicopter loading condition and related specifications. Test results meet the stability requirements at sea state code 4 and sea state code 2 with puncture conditions.

• Journal of information and communication convergence engineering
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• v.7 no.4
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• pp.580-585
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• 2009

Harmful Algal Blooms (HABs), caused by Cochlodinium polykrikoides that causative fishery mortality, impact on aquaculture and economic loss appear particularly in summer and fall seasons in the Korean seas. It was studied on characteristics of HABs in the South Sea of Korea by using satellite and in-situ data. The in-situ data encompassed oceanic and meteorological data from July to October 2002-2008 and satellite data from July to October 2002-2006. Chlorophyll concentrations were calculated using Seaviewing Wide Field-of-view Sensor images by an Ocean Color (OC4) algorithm, and HABs were estimated using the Red tide index Chlorophyll Algorithm (RCA). The HAB occurrences were dominant when water temperature was $22.6-28^{\circ}C$ in August. The frequency of the individual numbers during 2002-2008, the HABs more than 1000 cells/ml (alert condition), were 73.57 %. In meteorological data from July to September during 2002-2008, the average precipitation, the mean air temperature, the mean wind speed and direction, and the sunshine were 9.31 mm/day, $24.07^{\circ}C$, 2.34 m/s and easterly, and 1-11 h, respectively. Our results suggest that the upwelling is caused by southwesterly wind in summer season and the Tsushima Warm Current which have influenced on the dispersion and moving of HAB (chlorophyll). In addition, the fresh water from Nakdong River, as the source of nutrients, also influences the occurrence of HABs.