• Economic and Environmental Geology
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• v.37 no.3
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• pp.335-345
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• 2004

Total and extractable contents of heavy metals were measured in sediment and seafood from Bukhang and Boggil-ri tidal flats along the Mokpo coastal area, south-western part of Korean peninsular in order to assess the degree of metal pollution, metal bioavailability and metal hioaccumulation. The metal concentrations, except Pb were found to be greater than the background concentrations of sediments indicating the progress of cumulative contamination by anthropogenic origin of metals. The order of extractable metal concentrations in sediments were Mn(32-53 mg/kg)＞Zn(14-42 mg/tg)＞Cu(2.5-17.0 mg/kg)＞Pb(2.4-6.8 mg/kg)＞Cd(0.5-0.7 mg/kg). However, the amount of metals associated with extractable fraction of sediments were significantly high in Bukhang relative to Boggil-ri. Significant bioaccumulation of all metals, except Pb were observed in seaweed and benthos. The order of bioaccumulation of metals were: in concentration; all biota commonly, Mn(129-374 mg/kg)＞Zn(19-106 mg/kg)＞Cu(6-87 mg/kg)＞Cd(4.6-7.6 mg/kg)＞Pb(0.2-3.7 mg/kg), in BCF; Enteromorpha, Cd＞Mn＞Cu＞Zn＞Pb, Ilyoplax deschampsi, Cu＞Cd＞Mn＞Zn＞Pb, Urechis unicinctus, Cd＞Zn＞Mn＞Cu＞Pb. Some metal concentrations of Enteromorpha, especially Cu, Zn, weakly Pb in bukhang, Mn, Cd in boggili-ri, were correlate well with concentrations in sediment, indicating relatively more contaminated by the anthropogenic origin of metals in each tidal flat. The results clearly indicate that the seafood of bukhang, even of Boggili-ri known as clean area, are contaminated with metals.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.1
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• pp.1-13
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• 2011

The Yellow Sea Cold Water (YSCW) is formed by cold and dry wind in the previous winter, and is known to spread southward along the central trough of the Yellow Sea in summer. Water characteristics of the YSCW and its movement in the northern East China Sea (ECS) are investigated by analyzing CTD (conductivity-Temperature-Depth) data collected from summertime hydrographic surveys between 2003 and 2009. By water mass analysis, we newly define the North Western Cold Water (NWCW) as a cold water mass observed in the study area. It is characterized by temperature below $13.2^{\circ}C$, salinity of 32.6~33.7 psu, and density (${\sigma}_t$) of 24.7~25.5. The NWCW appears to flow southward at about a speed less than 2 cm/s according to the geostrophic calculation. The newly defined NWCW shows an interannual variation in the range of temperature and occupied area, which is in close relation with the sea surface temperature (SST) over the Yellow Sea and the East China Sea in the previous winter season. The winter SST is determined by winter air temperature, which shows a high correlation with the winter-mean Arctic Oscillation (AO) index. The negative winter-mean AO causes the low winter SST over the Yellow Sea and the East China Sea, resulting in the summertime expansion and lower temperature of the NWCW in the study area. This study shows a dynamic relation among the winter-mean AO index, SST, and NWCW, which helps to predict the movement of NWCW in the northern ECS in summer.

• Agribusiness and Information Management
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• v.9 no.1
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• pp.7-17
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• 2017

Agricultural water management has gained enormous attention in the developing world to alleviate poverty, reduce hunger and conserve ecosystems in small-scale production systems of resource-poor farmers. The story of food security in the $21^{st}$ century in India is likely t o be closely linked to the story of water security. Today, the water resource is under severe threat. The past experiences in India in general and in Andhra Pradesh in particular, indicated inappropriate management of irrigation has led to severe problems like excessive water depletion, reduction in water quality, water logging, salinization, marked reduction in the annual discharge of some of the rivers, lowering of ground water tables due to pumping at unsustainable rates, intrusion of salt water in some coastal areas etc. Considering the importance of irrigation water resource efficiency, Krishna Western Delta (KWD) of Andhra Pradesh was purposively selected for this in depth study, as the farming community in this area are severely affected due to severe soil salinity and water logging problems and hence, adoption of different water saving crop production technologies deserve special mention. It is quite disappointing that, canals, tube wells and filter points and other wells could not contribute much to the irrigated area in KWD. Due to less contribution from these sources, the net area irrigated also showed declining growth at a rate of -6.15 per cent. Regarding paddy production, both SRI and semi-dry cultivation technologies involves less irrigation cost (Rs. 2475.21/ha and Rs. 3248.15/ha respectively) when compared to transplanted technology (Rs. 4321.58/ha). The share of irrigation cost in Total Operational Cost (TOC) was highest for transplanted technology of paddy (11.06%) followed by semi-dry technology (10.85%) and SRI technology (6.21%). The increased yield and declined cost of cultivation of paddy in SRI and semi-dry production technologies respectively were mainly responsible for the low cost of production of paddy in SRI (Rs. 495.22/qtl) and semi-dry (Rs. 532.81/qtl) technologies over transplanted technology (Rs. 574.93/qtl). This clearly indicates that, by less water usage, paddy returns can be boosted by adopting SRI and semi-dry production technologies. Both the system-level and field-level interventions should be addressed to solve the issues/problems of water management. The enabling environment, institutional roles and functions and management instruments are posing favourable picture for executing the water management interventions in the State of Andhra Pradesh in general and in KWD in particular. This facilitates the farming community to harvest good crop per unit of water resource used in the production programme. To achieve better results, the Farmers' Organizations, Water Users Associations, Department of Irrigation etc., will have to aim at improving productivity per unit of water drop used and this must be supported through system-wide enhancement of water delivery systems and decision support tools to assist farmers in optimizing the allocation of limited water among crops, selection of crops based on farming situations, and adoption of appropriate alternative crops in drought years.

• Journal of Korean Society on Water Environment
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• v.18 no.4
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• pp.341-354
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• 2002

Heavy metal concentration/distribution in sediments and bivalves from the tidal flats in Saemankeum coastal area, western Korea, were investigated, Among 6 sampling sites, S2, S5 and S6 showed the higher levels of Zn, Cr, Ni, Cu and Cd contamination and S1 did the higher level of Pb contamination than other sites, while S-4 showed the lowest levels of these metal contamination. Overally, the levels of Zn, Cu and Pb concentrations in Sinonovacula constricta were estimated to be relatively high. The shell lengths of the collected mussels were linearly related to their dry weights of the whole soft parts, but the mussels collected from S3 were in a poor nutrition, resulting in the distinctively high levels of metal concentrations in the body. It was shown that in S. constricta, Cr, Ni, Cu and Zn are distributed equally into the whole soft parts or a little more into the flesh, after absorption, while Fe, Cd, Pb and Mn are transferred more into the non-flesh parts than into the flesh parts. In S. constricta, the heavy metal concentrations in the flesh increase with those in the whole soft parts. The bioaccumulation factors(heavy metal concentration in S. constricta/heavy metal concentration in sediment) showed that, of the examined metals, Cd is the most cumulative in the body of S. constricta, followed by Zn and Cu, while Mn, Cr, Ni and Pb are not cumulative.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.376-385
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• 2017

This study was conducted to understand the relationships between fish and zooplankton of distribution in the coastal waters of the East Sea from May to August 2016 using hydroacoustic. To distinguish between fish and zooplankton, we used the time varied threshold (TVT) method at the frequency of 120 kHz. As a result, the mean nautical area scattering coefficient (NASC) of fish was highest at $913m^2/n.mile^2$ in June and lowest at $315m^2/n.mile^2$ in July. The mean NASC of zooplankton was highest at $247m^2/n.mile^2$ in May and lowest at $70m^2/n.mile^2$ in July. The mean NASC of fish and zooplankton showed a significant difference (P < 0.05) with high correlation ($R^2=0.84$). In addition, there was no significant difference in the mean NASC of fishes and zooplankton by depth (t-test, person correction = -0.17, p > 0.05).

• Journal of fish pathology
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• v.13 no.1
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• pp.67-73
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• 2000

This study was carried out to elucidate the preliminary ecosystem of the heterotrophic bacterial flora in Kunsan Bay located in western costal area of Korea. Samples were collected at 5 sampling stations. Among 123 bacterial isolates, 9 genera of bacteria were appeared as follows; Vibrio spp.(44 isolates/35.7%), Pseudomonas spp.(42 isolates/34.1%), Aeromonas spp.(11 isolates/8.9%), Moraxella spp.(9 isolates/7.3%), Enterobacteria spp.(6 isolates/4.8%), Bordetella spp.(3 isolates/2.4%), Alkaligenesis spp.(3 isolates/2.4%), Flavobacterium spp.(2 isolates/1.6%), and Staphylococcus spp.(3 isolates/2.4%) respectively. Total viable heterotrophic bacteria was ranged from $5{\times}10^3$ to $1{\times}10^5$ CFU/ml and the most abundant viable counts of bacterial population were showed at the stations 2 and 3. This result indicates that the coastal area around Kunsan bay is getting to contaminate far more by municipal wastewaters and industrial byproducts. and so the outbreak of the bacterial diseases will be increased in fish farms.

• Journal of fish pathology
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• v.20 no.3
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• pp.201-209
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• 2007

Viral hemorrhagic septicemia (VHS) is one of the most serious viral disease of farmed rainbow trout and some marine fishes in Europe and North America. It has been reported in various marine fish species of Asian countries and induced cause mass mortality in Japanese flounder (Paralichthys olivaceus) culturing in Korea. The aims of this study were to monitor VHSV in wild marine fishes and to give critical information for controling the disease through prophylactic methods. Prevalence of the viral disease, geological distribution and reservoir of the virus were investigated using wild marine fishes captured in southern coast and east china sea for two years. (Reverse Transcriptase Polymerase Chain Reaction) RT-PCR results showed that VHSV were detected in 17 (10.6%) out of 160 fish. G gene sequences of viral strains isolated in this study were closely related to that of a reference strain, KVHS01-1, belonging to VHSV genotype Ⅰ. The results suggest that some of wild marine fishes are VHSV carriers and may spread the pathogen directly to fish farmed in coastal area.

• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.69-79
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• 2019

The coastal area forms various sedimentary layers according to the environmental conditions such as the topography and geological features of the upper region of the river, ocean currents, and river mouth. Therefore, identifying the characteristics of the marine clay deposited in the coastal area plays a key role in the investigation of the formation of soft ground. In general, alluvial grounds are formed by a variety of factors such as changes in topography and natural environment, they have very diverse qualities depending on the deposited region or sedimentation conditions. The most important thing for the construction of social infrastructures in soft ground areas is economical and efficient treatment of soft ground. In this study, the author collected data from diverse laboratory and field tests on five areas in western and southern offshore with relatively high reliability, and then statistically analyzed them, thereby presenting standard constants for construction design. Correlation between design parameters such as over consolidation ratio, preconsolidation pressure was analyzed using linear and non-linear regression analyses. Also, proposed distribution characteristics of design parameters in consideration of each region's uncertainty through statistical analyses such as normality verification, outlier removal.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.179-183
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• 2001

Shortnecked clam, Ruditapes philippinarum, is one of the very important shellfish produced in south-western coast of Korea. But it's ready to be polluted and have sand in flesh because it mainly inhabit in silt at the inside of coastal area. This study was carried out to obtain informations about the elimination of sand in shortnecked clam harvested from western coast of Korea. During rearing shortnecked clams in water tank, the elimination rates of sand from them at 6, 13, 23, $28^{\circ}C$ were 59.0, 88.2, 97.9, $96.1^{\circ}C$ after 48 hours, respectively. The sand was eliminated above $95^{\circ}C$ from the shellfish at 32,9 to $40\%_{\circ}$ of salinity after 48 hours. But the sand elimination from them was incomplete and inconsistent at 10 to 20 of salinity. The sand was eliminated rapidly at pH 1.9 to 9.0 however, its elimination was not effective at neutral or acidity range, It was found that the sand elimination was most effective at $23^{\circ}C, 35\%_{\circ}$ salinty and pH 9.0. Reasonable flow rate for sand eliminate in shortnecked clam was above 150 L/min./shellfish $m^3$ under both 3,000 and 4,000 L/shellfish $m^3$, and above 100 L/min,/shellfish $m^3$ under both 6,000 and 8,000 L/shellfish $m^3$ in water tank.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.184-189
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• 2001

Surf clam, Mactra veneriformis, is a important shellfish produced in south-western coast of Korea. But it's ready to be contaminated and have sand in flesh because it mainly inhabit in silt at tHe inside of coastal area. We determined optimum conditions for the sand elimination and microbial depuration in the shellfish harvested from western coast of Korea. It was found that the most effective conditions of process water for the sand elimination were $23^{\circ}C$, $32.9-35.0\%_{\circ}$ salinity and pH $7.9\~9.0.\;A$ surf clam contained about 210 mg of sand whose $94\%$ was eliminated after 24 hours in natural sea water ($32.9\%_{\circ}$ , pH 7.9) controlled at $23^{\circ}C$. To eliminate both sand and microorganisms contaminated in surf clam, the process water should be run during at least 36 hours for the former and 24 hours for the latter at 150 L/minute/$m^3$of shellfish, when its volume was above 4,000 L/$m^3$ of shellfish in 2 tons of tank.