• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.1 s.24
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• pp.1-8
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• 2006

To investigate the variation of marine environments due to set up of artificial structure, we carried out field observations. High temperature and salinity waters near the south frontal area were distributed clearly in the southeastern part of study area during summer season The variation of current structure was also occurred around study area where artificial structure set up. In 2005 after set up of artificial structure, the nutrient concentration increased greater than that in 2002 before set up artificial structures. To illustrate the characteristics of marine environment due to set up of artificial structure, quantitative analyses on the effect of artificial structure are important.

• Magazine of the Korean Society of Agricultural Engineers
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• v.8 no.1
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• pp.1055-1063
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• 1966

Ground water hydrology may be defined as the science of the occnrrence, distribution, and movement of water below the surface of the earth. Geohydrology has an identical connotation, and hydrogeology differs only by its greater emphasis on geology. Ground water referred to with out further specification is commonly understood to mean water occupying all the voids with in a geologic stratum. This saturated zone is tobe distinguished from an unsaturated, or aeration zone where voids are filled \yith water and air. Water contained in saturate:! zones is important for engineering works, geologic studies, and water supply developements Conseqently, the occurrence of water in these zones will be emphasized here. Un-saturated zones are usualiy found above saturated zones and extending upward to the ground surface. Because this water includes soil moisture with in the root zone, it is a major concern of agricultlre, botmy and soil science. No rigid demarcation of waters, between the two zones is possible, for they possess an iriterdependent boundary and water can move from zone to zone in either science, including eology, hydrology, meteorology, and oceanography are concerned with earths water, but ground water hydrology may be regarded as a specialized science combining elements of geology, hydrology, and fluid mechanics. Geology governs the occurrence and distribution of ground water, hydrology determines the supply of water to the ground, and fluid mechanics explains its movement. To provide maximum development of grofnd water resources. for benefical use requires thinking in terms of an entire ground water basin. In order to inorease the natural supply of ground water, man has attempted to artifially recharge ground water basins. Coastal aquifers come in contact with the ocean at seawater of the coastline. Fresh ground water is discharged in to the ocean. the seaward flow of ground water has been decreased or even reversed, Sea water penettating in land in aquifer.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.2
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• pp.139-147
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• 2010

This study monitored a variety of marine fish communities in artificial reefs unit of the total 5 types (Dice type, Octagonal turtle type, Two-stage tube type, Gazebo type, Tetrapod type) which are located in the marine ranching at Jeju island by scuba diving in May, July, October and December 2009. Underwater photographing was accomplished at total 3 phases (condition of artificial reefs photographing, concentric circle movement photographing and line transect photographing). The preservation condition of artificial reefs facility was very good, and the dominant species were Chromis notatus, Sebastes thompsoni, Oplegnathus fasciatus and Halichoeres poecilopterus. Fish abundance was high in May and June, and low in October and December, 2009. Chromis notatus was dominant at the all types of artificial reefs, Halichoeres poecilopterus for Gazebo type and Tetrapod type of artificial reefs, and Sebastes thompsoni for Dice type, Octagonal turtle type and Two-stage tube type of artificial reefs.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.3
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• pp.368-377
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• 2014

Small yellow croaker is one of the important stocks in Korean waters. In this study, we conducted sea trials to estimate optimum height of a drift gill net for effective fishing of small yellow croaker. In the trial using existing net which has 9.2m in height, there was 22 species (1,180 fishes, 99.9kg) caught. The catch (in individuals) of small yellow croaker, especially larger fishes (over 22cm in FL), was higher as part of net height is higher, while the number of species bycaught and the catch of those species were higher as part of net height is lower. In the trial using extension net which has 18.4m in height, there was 27 species (2,030 fishes, 151.7kg). It showed same pattern with existing net in the section I to III, however, in the section IV which is over 13.8m of net height, the catch sharply decreased. The number of species bycaught and the catch of those species using extension net were also same as results using existing net. It showed that section III (9.2-13.8m) where is upper-middle part of the net has caught most of catch and large fishes having over 22cm in length. Through these results, it is judged that the setting depth of the net where is 4.6-13.8m above the sea bottom is the best to reduce bycatch and catch much more large size fishes, and the catch per net is proportional to filtering area of net. Therefore the Fisheries Resource Management Act (the clause 1, article 10) on the amount of usage for offshore drift gill net need to be considered not only length of a net but also net height.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.3
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• pp.286-292
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• 2017

The Coastal VTS will be continuously constructed to prevent marine traffic accidents in the coastal waters of the Republic of Korea. In order to provide the best traffic information service to the ship operator, it is important to understand the navigation risk factor. In this study, we analyzed the navigational hazards of Gunsan coastal area where the coastal VTS will be constructed until 2020. For this purpose, major traffic flows of merchant ships and density of vessels engaged in fishing were analyzed. This study was conducted by Automatic Identification System (AIS) and Vessel Pass (V-PASS) data. The grid intervals are 10 minute ${\times}$ 10 minute (latitude ${\times}$ longitude) based on the section of the sea. A total of 30 sections were analyzed by constructing a grid. As a result of the analysis, the major traffic flows of the merchant vessels in the coastal area of Gunsan were surveyed from north to south toward Incheon, Pyeongtaek, Daesan, Yeosu, Pusan and Ulsan, and from east to west in the port of Gunsan Port, 173-3, 173-6, 173-8, 183-2, 183-5, 183-8, 183-3, 184-1 and 184-2. As a result of the study, the fishing boats in Gunsan coastal area mainly operated in spring and autumn. On the other hand, the main traffic flow of merchant ships and the distribution of fishing vessels continue to overlap from March to June, so special attention should be paid to the control during this period.

• The Korean Journal of Malacology
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• v.22 no.1 s.35
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• pp.63-86
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• 2006

A list of species of bivalve mollusks, their local distributions and relative abundance in Yeongil Bay were analysed. Species richness ranging from 1 to 37 species was low (less than 10) in some stations at the entrance and in the central part of the bay. Fifteen species (Acila insignis, Nucula tenuis, Yoldia notabilis, Mytilus galloprovincialis, Arca boucardi, Axinopsida subquadrata, Felaniella usta, Mactra chinensis, Raeta pulchella, Nitidotellina hokkaidoensis, Theora fragilis, Alvenius ojianus, Callithaca adamsi, Ruditapes philippinarum and Laternula anatina) were most frequently encountered, and seven of them were most abundant numerically (per sample): Th. fragilis in the inner bay, A. insignis, N. tenuis, and A. ojianus in the outer bay, and C. adamsi, A. subquadrata, R. puichella in both parts. Local distributions of common species were described and presented in plotted data, and three distribution patterns were recognized. Biogeographical analysis shows that a majority of species (55%) belongs to the subtropical group, tropical-subtropical species (16%) play a relatively significant role, and the percentage of boreal (temperate) and boreal-arctic species is 18% which characterizes the whole fauna as subtropical. Zonal-biogeographical composition and number of species in families in Yeongil Bay are compared with those of some Japanese (Wakasa and Mutsu) and Russian (Peter the Great, Possjet and Amursky) bays of the East Sea. The absence of a number of typical warm-water embaymental mollusks in Yeongil Bay found in the north further East Sea and Japan, and the similar zonal-biogeographical structure of the inner and outer bay faunas are explained by active water exchange due to the openness of the bay, relatively low summer temperatures, and presence of upwelled cold waters.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.211-215
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• 2010

The genus Perkinsus are parasitic protozoans that cause massive inflammatory responses in infected marine shellfish worldwide. This ultimately leads to great economic losses. This study examined the effects of water temperature and salinity on the formation of prezoosporangia and zoosporangia in order to understand the ecology of the pathogens. The induction of prezoosporangia from trophozoites occurred readily at higher water temperatures (20 and $30^{\circ}C$) and they had larger diameters than those incubated at lower temperatures (4 and $10^{\circ}C$). The formation of zoospores in prezoosporangia was also strongly influenced by water temperature and salinity; prezoosporangia exposed to water temperatures of 20 and $30^{\circ}C$ and salinities of 20 and 30 ppt had high rates of zoosporulation, while no or very low rates of zoosporulation were observed at temperatures below $10^{\circ}C$ or salinity below 10 ppt. Our data will be useful for the development of strategies to counter P. olseni proliferation in Korean waters.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.3
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• pp.475-482
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• 2019

Over 3,200 large baleen whales including 3,173 fin whales, 7 blue whales and 28 humpback whales were hunted by Japanese whaling companies in the Yellow Sea during Japanese colonial period (1916~1944). As a result, these large baleen whales are under the endangered state in the Yellow Sea. The Yellow Sea had good living conditions for large baleen whales in the water temperature ($4{\sim}26^{\circ}C$) and food supply. The whaling on the large baleen whales was carried out mainly from early winter to late spring. The possibility of large scale whaling was caused by the migration of these baleen whales from other areas for the feeding on abundances of Euphausia pacifica in the surface layer during these seasons. During summer and autumn season, the baleen whales moved to other areas (good feeding ground as Woolsan offshore waters), because Euphausia pacifica stayed below the strong themocline which was formed from June to October in the Yellow Sea.

• Journal of Navigation and Port Research
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• v.43 no.2
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• pp.93-100
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• 2019

In 2001, about 20 years after the introduction of the standard buoys, the natural environment and maritime traffic flow changes in the waters near Korea and the necessity of improvement of the AtoN (Aids to Navigation) maintenance was suggested. The IALA provides guidelines for maintenance and management of AtoN, and Korea provides guidelines for the management and operation of standard buoys by means of the Enforcement on the AtoN laws. The objective of this study was to investigate the installation status and the repair status of the standard type buoys by sea area in order to improve the management and operation of the steel standard buoys. In addition, a survey was conducted on the improvement of the steel buoy fouling and the improvement of the lifting inspection cycle towards on the AtoN managers and producers of the representative authority by sea area. In the case of LL-26 (M) buoy type, the standard type buoy installation status of Korea in 2017 was 57.1%, and the LL-26 (M) type was 58.9% showing the highest repair rate. According to the results of the survey on buoys fouling, 51.2% were caused by the attachment of shellfish, and 43.2% were caused by bird feces. The results of the survey on the improvement of the regular buoy inspection cycle showed that the measures are to maintain the current inspection period of 2 years regardless of the characteristics of the sea area (water depth, inside and outside port, buoy size, etc.).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.4
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• pp.306-314
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• 2018

Species composition and seasonal variation of aquatic organism at Baekryeong-do, Korea were investigated using pots in 2016. A total of 42 species, 90,050 individuals and 2,351,666 g of aquatic organism were collected. Among them, there were 12 species and 3,826 individuals of fish, 15 species and 51,237 individuals of crustaceans, 2 species and 54 individuals of cephalopods, 7 species and 33,981 individuals of gastropods, 2 species and 757 individuals of echinodea, 2 species and 187 individuals of shellfish, and 1 species and 8 individuals of holothuroidea. The dominant species in number of individuals were Pagurus ochotensis, Neptunea cuming, Cancer gibbosulus, and Buccinum yokomaruae, which accounted for 70.0% of the total number individuals collected. The dominant species in biomass were Neptunea cuming, Portunus trituberculatus, Cancer gibbosulus, and Pagurus ochotensis, which accounted for 65.3% of the total biomass collected.