• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.3
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• pp.241-248
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• 2002

The combined hydroacoustic and demersal trawl surveys to investigate the distribution characteristics of fish schools in the Yellow Sea and the East China Sea were carried out during the spring of 1997 by the training ship "Nagasaki Maru" of Nagasaki University. Fish samples were collected by bottom trawling from 9 trawl stations randomly selected in the survey area, and the species and length compositions of trawl catches are examined. Hydroacoustic data were collected by using a Furuno FQ-50 scientific echo sounder operating at 50KHz and the data stored in field were later processed in the laboratory. The results obtained can be summarized as follows ：1. In the 9 trawl surveys conducted in the Yellow Sea and the East China Sea, 78 species including 80 species of fishes, 4 species of Cephalopoda and 6 species of Crustacea, were identified. The most abundant species in these stations were swimming crab(Portunus trituberculatus), Japanese horse mackere(Trachurus japonicus), redlip croaker(Larimichthys polyactis) and the catch per one hour in each station ranged 7.7 to 182.5 kg/hour. 2. The mean volume backscattering strength for the entire water column and the bottom layer of the 0-10 m from bottom friction were -74.6 ㏈ and -68.2 ㏈, respectively. That is, the mean volume backscattering strength for the bottom layer was 6.4 ㏈ higher than that for the entire water column 3. In the surveys during the spring of 1997, the geographical distribution characteristics of fish schools suggests a trend of decreasing fish abundance toward the coast area of Korea and the highest demersal concentrations appeared in waters between the Cheju Island and the Tsushima Island 4. The distribution density of fish school in the East China Sea and Yellow Sea during the 1997 acoustic survey were estimated to be 6.65$\times$10$^{-5}$ kg/㎥ in the entire water column and 2.86$\times$l0$^{-4}$ kg/㎥ in the bottom layer, respectively.pectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.644-655
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• 2020

This study focuses on the margin of human error when a navigator is embarrassed by the psychological fear of collision in a close-quarter situation (CQS) and is unable to perform as per the prescribed collision avoidance measures. The purpose of the study is to identify the effects of the navigator's personal characteristics or factors in relation to on-board career (OC), license rating (LR), and age on the perceived collision risk (PCR) in CQSs. In order to obtain quantified data regarding the collision risk perceived by the navigator in four typical CQSs between their own ship and a target ship, this study measured and collated the heart rate variability of 30 navigators on their own ship when two ships approached each other at a speed of 10 knots from 2.5 nautical miles to a collision situation. According to a multiple regression analysis of the measured values, the navigators' OC and LR factors had negative effects on the PCR, while the age factor had no significant effect on PCR. The t-test results showed that the PCR value was significantly higher for navigators with an OC ≤ 4 years than for those with an OC ≥ 5 years, and the LR factor was significantly higher for a class 4~6 group than for a class 2~3. This finding may be applied to the development of collision risk warning systems, particularly for navigators.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.4
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• pp.23-36
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• 2000

Bottom sea waters in eight stations including from inner bay to outer bay to understand the importance of the submarine groundwater discharge for the environmental assessment of Chinhae Bay was collected in August 1999 and January 2000. Generally, /sup 222/Rn is very useful tracer to assess the submarine groundwater discharge because it is 2-4 orders of magnitude more concentrated in groundwater compared to surface water. The /sup 222/Rn activities ranged between about 33 to 182 dpm/100kg within the bay. Higher activities more than 100 dpm/100kg were found at the inner bay. The /sup 226/Ra activities, its parent, however, were little different between stations. /sup 222/Rn activities at the same station varied with season. It suggests that the major source of /sup 222/Rn is not from the bottom sediment, but from the change of submarine groundwater discharge by precipitation. The contents of Cl/sup -/ and SO/sub 4//sup 2-/ in the groundwater of Wonjeon-ri were very high as 1,312 and 369 ppm, respectively, indicating that this groundwater along the Chinhae coast was affected by seawater. Therefore, the submarine groundwater in the inner Bay may discharge to the overlying water. It indicates that these submarine groundwater discharges may play an important role as another important source of nutrients in the Chinhae Bay, because groundwater around the Chinhae Bay showed high concentration of dissolved inorganic nutrients (average , nitrate>174 μM, silicate>262 μM). Therefore, further studies are required to assess the contribution by the submarine groundwater discharge in the biogeochemical processes of the Chinhae Bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.4
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• pp.298-306
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• 2010

A sanitary survey was conducted to evaluate the water quality and mussel (Mytilus edulis) conditions of two administrative shellfish growing waters: those designated as shellfish growing water for export, and adjacent waters on the east coast of Changseon Island, Namhae, Korea. In all, 1,656 seawater and 166 mussel samples were collected at 46 stations for seawater and five stations for the shellfish from January 2007 to December 2009. Both seawater and mussels were examined for total coliforms and fecal coliforms. The standard plate count and most probable number of Escherichia coli were also determined for the shellfish samples. The range of the geometric means and the estimated 90th percentiles of fecal coliform for seawater samples at each station were <1.8-4.1 MPN/100 mL and <1.8-22.3 MPN/100 mL, respectively. The sanitary conditions for both shellfish growing areas, the designated shellfish growing area and adjacent area in Changseon, met the 'Approved area' criteria of the United States National Shellfish Sanitation Program. The range of E. coli detected in mussels in these areas was <20-500 MPN/100 g; and only 3 of 166 samples exceeded 230 MPN/100 g, the European standard for the consumption of raw bivalves. Therefore, the mussel farms in the Changseon area are classified as 'Class A' according to criteria set in European Community regulations. However, the levels of E. coli in mussels in parts of the designated shellfish growing area and adjacent area exceeded the bacterial limits after rainfall exceeding 45 mm. Further studies are needed to fully define the conditions leading to a temporary closure to harvest after a rainfall event.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.129-138
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• 2020

This study recognizes problems in the current system of providing navigation safety information (NSI), which is centered on merchant ships, to prevent maritime accidents of fishing boats and small vessels in coastal areas. The system proposed in this study is an effective method of providing NSI to support the safe navigation of small vessels such as fishing boats. First, the status and characteristics of recent maritime accidents were examined, and NSI service targets were identified. Second, the limitations of the current NSI system were determined, and measures were proposed to establish an NSI Integrated Platform (NSIP) that ensures the integration, accessibility, and usability of NSI for a substantial portion of the public. Third, to utilize the NSIP, various NSIs are applied as additional information for the electronic chart system used in the e-navigation ship terminals being developed in connection with the Korean e-navigation project. Functions that set the audiovisual alarm function to automatically operate when a ship enters a navigation risk zone is proposed. These functions are technically achieved by reviewing expert opinions of related organizations and professional producers. The results of this study suggest that NSI can be applied to small vessels such as fishing boats, through the Korean e-Navigation project, to prevent maritime accidents caused by the human error of navigators.

• Ocean and Polar Research
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• v.35 no.4
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• pp.299-312
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• 2013

This study analyzed the species composition and density of a macrobenthic community according to variations in the thermal discharge volumes of a nuclear power plant before, during, and after the shutdown of the nuclear power plant during two periods. In this study, 369 macrobenthic fauna species were collected, and their mean density was 1,712 ind. $m^{-2}$. The number of species and diversity of macrobenthic fauna decreased with distance from the thermal discharge area, regardless of whether the nuclear plant shutdown or not. Many macrobenthic taxa appeared near the thermal discharge area, but polychaetes species were more prominent in outer areas than at the discharge area. The density of macrobenthic fauna decreased with distance from the thermal discharge area during a plant shutdown in the fall of 2011, but increased, except at two sites, near the discharge area in the winter of 2012. Cluster analysis indicated that the spatial distribution of the macrobenthic community changed in areas near the nuclear power plant after a shutdown period; that is, the station group I, in areas near the nuclear power plant, became narrower after the shutdown, but it recovered to previously occupied areas after the nuclear power plant began operating again. Opportunistic species, such as the polychaetes Lumbrineris longifolia (= Scoletoma longifolia) and Mediomastus californiensis, which were present in high densities near thermal discharge areas, decreased after the shutdown but recovered after the plant re-opened. The number of species and diversity of the macrofauna and the density of dominant species showed a significant correlation with temperature, except in winter periods. The results of this study revealed that changes in the amount of thermal discharge before and after the shutdown of a nuclear power plant could exert an influence on the structure of macrobenthic community within the thermal discharge areas depending on the season.

• Journal of Wetlands Research
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• v.6 no.1
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• pp.57-72
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• 2004

Macrobenthic fauna were studied on a tidal flat in Garolim Bay in July 2002, in order to understand their spatial distribution with the surface sediment types. Forty-nine stations were set on the tidal flat. A total of 147 species was sampled with the mean density of $1,140ind./m^2$ and the mean biomass of $157.2g/m^2$. The polychaetes were speices- and density-dominant faunal group with 64 species and the mean density of $791ind./m^2$. Mollusks were biomass-dominant faunal group with $132.0g/m^2$. Major dominant species were two polychaetes, Mediomastus californiensis with the mean density of $374ind./m^2$ and Heteromastus filiformis with $224ind./m^2$. Also mollusks such as Umbonium thomasi, Batillaria cumingi and Ruditapes philippinarum was relatively high in the mean density, showing the density of 45, 42, $32ind./m^2$ respectively. Especially, U. thomas was distributed in the mouth of the bay, where sediment grain size is rather coarse, and R. philippinarum at near tidal channel. Based on the cluster analysis, the macrobenthic community on the tidal flat was classified into seven station groups depending on the benthic environmental parameters(sediment types). Compared with other Korean tidal flats, species richness of Garolim tidal flats is more and less low.

• Korean Journal of Remote Sensing
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• v.32 no.6
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• pp.639-645
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• 2016

Yeongjong-do is seventh largest island in the west coast of Korea which is 4.8 km away in the direction of south-west from Incheon. The mudflat area around the Yeongjong-do has variable dimension according to tide level. In addition, Yeongjong-do is important area with high environmental value as wintering sites for migratory birds. The mudflat of Yeongjong-do is also meaningful region because it is used as place of education and tourist attraction. But, there are increasing concerns about preservation of mudflat area caused by artificial development such as land reclamation project and Incheon airport construction. In this paper, mudflat area was detected using Landsat 7 ETM+ images that United States Geological Survey (USGS) is providing the data in 16 days period. The false color composite was made from band 7, 5, and 3 that could dividing boundary between water and land for the purpose of appearance of boundary line in mudflat region. This area was calculated using results of classification based on false color composite images and was digitized through repetitive algorithm during research of period. Therefore, the change of northeastern area in Yeongjong-do was detected according to tide level during 16 years from 2000 to 2015 on the basis of providing period at tide station. This paper will expect as indicator for range of area in same tide level prior to the start of the research for preservation of mudflat. It will be also scientific grounds about change of mudflat area caused by artificial development.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.180-189
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• 2001

This study was conducted to investigate the macrobenthic community in Ulsan Bay and Onsan Bay, in November of 1997. The density of benthic animals was 535 md./m2, and the number of species was 117. Polychaeta was the most dominant faunal group, comprising a total of 63 species, and its density was 380 md./m2 The most dominant benthic macrofauna was Cirratulrus cirratulas (2.7%), and followed by Tharyx sp. (16.6%), Ruditapes philippinarum (16.1%), Lumbrineris longifolia (10.3%) and so on. The dominant species occupied their distinct unique distribution area. Tharyx sp., R. philippinarum and Grandidierella sp.1 occurred mainly in Ulsan Bay, L. longifolia and Euchone sp. in Onsan Bay, and C. cirratulas and Cirriforimia tentaculata in both bays. By cluster analysis, study area was divided into 4 station groups: Northern Ulsan Bay (Al), the middle area of Ulsan Bay (Bl), offsea area between Ulsan Bay and Onsan Bay (Bll), and Onsan Bay (C). Northern Ulsan Bay was characterized by low species number and high density. The dominant species were C. cirratulas R. philippinarum and Tharyx sp. The middle area of Ulsan Bay was by low species number and density, and its characteristic species was Grandidierella sp.1. The offsea area between Ulsan and Onsan Bay was by high species number and low density. Onsan Bay was by high species number and high density, and its important species were L. longifolia and Euchone sp.

• Journal of Korea Water Resources Association
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• v.40 no.7
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• pp.571-583
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• 2007

The effects of climatic changes owing to urbanization, geographical and topographical conditions on Penman-Monteith reference evapotranspiration, and energy and aerodynamic terms of Penman-Monteith reference evapotranspiration have been studied. In this study, 56 climatological stations including the Seoul metropolis in South Korea have been selected, and the area of study site was set at $314\;km^2$. The climatological station is centrally located In the study area with a 10 km radius. The geographical and topographical characteristics of these sites were examined using GIS analysis. Land use status of the study area was also examined to estimate the extent of urbanization. The study results indicated that the variation of reference evapotranspiration rate is closely related to urbanization in most climatological stations. The level of change in reference evapotranspiration was higher in areas with higher urbanization rates. The change in reference evapotranspiration appears to be caused by temperature rises following heat island phenomena due to urbanization, and by the decrease in humidity, wind speed and sunshine duration due to the Increase in residential areas in urban districts. Especially, the humidity decrease causes a significant decrease in evapotranspiration rate. The study results showed that climatic change due to urbanization and proximity to the coast had the greatest effect on reference evapotranspiration.