• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.557-566
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• 1996

An ecological study on pathogenic vibrios was done in the aquatic environments of southern coast of Korea during summer in 1995, to investigate the distribution and relationship between pathogenic vibrio and zooplankton. Furthermore, special emphasis was given to study on the efforts of zooplankton existence on the wintering of Vibrio cholerae in the aquatic region in Korea. During the study period, pathogenic vibrios were isolated from the samples such as V. parahaemolyticus, V. vulnificus, V. mimicus, and V. cholerae non O1, but V. cholerae O1 was not detected in any sample submitted in this study. Adsorption ratio of V. parahaemolyticus onto zooplankton was higher than that of E. coli. The efficiency of adsorption was found to be on the concentration of NaCl and other ions found in sea water. For example, adsorption ratio of V. parahaemolyticus were $75\%\;at\;5\%_{\circ}$ of NaCl solution and $55\%$ at same salinity of diluted sea water, but those were decreased as $20\%\;and\;7\%\;at\;15\%_{\circ}$ salinity of NaCl solution and diluted sea water, respectively. In addition, survival period of pathogenic vibrio was extended in the presence of live copepods at $25^{\circ}C$, but zooplankton existence has no significant effect on the survival rate at $5^{\circ}C$ in closed microcosm and also microalgae and dead copepods do not affect on the survival of V. parahaemolyticus. According to these experimental results, zooplankton has positive effects on the growth and survival rate of pathogenic vibrios in sea water during the summer season, but copepods have no significant effects on the growth and survival rate of them in winter season in Korea. Finally, authors suggest that V. cholerae is not able to over winter with zooplankton in adjacent sea water in Korea.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.214-226
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• 2013

To understand the changing patterns in phytoplankton communities, we conducted 12 surveys along the Nakdong River, its estuary, and adjacent coastal areas between January 2011 and October 2012 (during the period of barrage construction and sediment dredging). Monthly precipitation ranged from 0 to 502 mm during the survey period, and salinity ranged between 0.1 psu and 0.3 psu in the Nakdong River, regardless of the depth, indicating no seawater influence, while salinity showed large seasonal fluctuations in the estuarine and coastal station, ranging from 0.1 psu to 34.8 psu. A total of 402 phytoplankton species were identified, 178 species from the river and 331 species from the estuary and coastal areas. Phytoplankton standing crop increased in 2012 compared to that in 2011, and was found to be highest in the river, followed by the estuary and coastal areas. Among the top 20 species in frequency of occurrence and dominance, Stephanodiscus spp., Aulacoseira granulata, and Aulacoseira granulata var. angustissima and Pseudo-nitzschia spp. were important species along the river-estuary-coastal areas. Diatoms were the major taxonomic group inhabiting the Nakdong river-estuary-coastal areas. A comparison of seasonal dominant phytoplankton species revealed a slight decrease over the years, from 13 species in 2011 to 10 species in 2012. However, no significant difference was found in the diversity of phytoplankton species between the two survey years, although lightly greater diversity was observed in the coastal areas than in the river and estuary. Cluster analysis with community composition data revealed that the community structure varied significantly in 2011 depending on the time of survey, while in 2012, it hardly showed any variation and was simpler. An increase in the phytoplankton standing crop, fewer dominant species, and simpler community structure in 2012 compared to those in 2011 are probably due to the rapid environmental changes along the Nakdong River. To investigate these ecological relationships, it is necessary to conduct further studies focusing on integrated analyses of biocenosis, including phytoplankton with respect to the changes in nutrient distribution, variation of freshwater discharge, and effect area of freshwater in the Nakdong estuary and adjacent coastal areas.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.457-467
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• 2019

To investigate the long-term variation characteristics of nutrients in the east coast of Korea, water temperature, salinity, dissolved oxygen, and nutrients were measured at three stations of Sokcho, Jukbyeon and Gampo coasts for five years from 2013 to 2017. For five years, the water temperature of the East Sea coast was in the range of $1.2{\sim}28.8^{\circ}C$, the salinity was in the range of 30.63~34.79 and the dissolved oxygen (DO) was in the range of 3.53~7.64 mL/L. Distribution and variation of the water environment factors in the study area were determined by the vertical stratification of water column and distribution of water temperature. The high DO concentration in Sokcho coast From 2015 to August 2016 is presumed to be the result of the southward inflow of North Korean Cold Water (NKCW). Concentrations of dissolved inorganic nitrogen (DIN, $NH_4-N+NO_2-N+NO_3-N$) ranged $0.11{\sim}24.19{\mu}M$, phosphate concentration ranged $0.01{\sim}1.75{\mu}M$, and silicate ranged $0.17{\sim}32.80{\mu}M$. The N:P ratio was in the range of 0.7~54.3 (mean 15.2) and the N:P slope was in the range of 11.67~13.75. The N:P ratios in this study were lower than the Redfield ratio (16), indicating that nitrate did act as a limiting factor in phytoplankton growth. The correlation ($R^2$) of total N:P ratio was as high as 0.95, indicating that the effect of the surrounding land or non-point sources was not significant. In conclusion, the spatial and temporal variation of nutrients in the east coast of Korea was determined by the vertical mixing of water mass with thermocline and mainly affected by physical factors such as influx of external water masses and coastal upwelling, and the influences from inflows from the land were minimal.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.176-186
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• 2000

The present study was carried out to clarify the structure and dynamics of copepod community and the relationship between this community and environmental factors during the period from February 1998 to July 1999. Copepods consists of 21 genera and 32 species, monthly variations of number of species were 15 species in May, 1998 and 2 species November, 1998. The number of species were 22 species in station 12 and station 1, 2, 3 occurred nauplii of copepoda only. Average abundance ranged from $8,330\;ind./m^3$ (in June, 1999) to $177\;ind./m^3$ (in November, 1998). Relationships between water temperature and number of species were as follows: 20 species occurred from 20.1 to $25.0^{\circ}C$ and nuplii of copepoda only occurred from 0.0 to $5.0^{\circ}C$. The number of species by salinity range were 19 species in $20.1{\sim}25.0%_o$ and 9 species in $0{\sim}0.5%_o$. The number of species by trophic state index (TSIm) of chlorophyll a were 25 species in oligotrophic state and 9 species in eutrophic state. Relationships between pH and number of species were as follows: 20 species occurred from 7.6 to 8.0 and from 9.1 to 9.5 was none. The number of species by DO range were 22 species in 6.5 to 7.5 mg/l and 1 species in 14.5 to 15.5 mg/l. The percentage calculated effect by stepwise multiple regression of the pearson correlation coefficient value of environmental factors and copepoda abundance (station 1-station 4) revealed that positive effect was 15.49% in COD, 25.86% in $Cl^-$, 19.75% in $NO_2-N$ and negative effect was 28.30% in $NO_3-N$. Also, Positive effect (station 5-station 12) revealed that 29.49% in water temperature, 28.27% in $NO_3-N$, 22.87% in $NO_2-N$ and negative effect was 30.18% in conductivity and 13.53% in DO.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.68-76
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• 2008

This study examined the inhibition effects of a freshwater bivalve (Unio douglasiae) and a submerged plant (Potamogeton crispus) on the cyanobacterial bloom (Oscillatoria sp.). The experiment were conducted in aquarium $(50cm{\times}65cm{\times}120cm)$ with lake sediments in the bottom of the aquarium in 10 cm thick. Before the experiments, artificial cyanobacterial bloom was induced with the addition of lake sediment and CB medium. Total 12 transparent acrylic cylinders (${\Phi}19cm$, height 40 cm) were placed in the aquarium, and within which bivalves and plants were placed in various conditions such as the control (C), plant addition (P:5 stems), mussel addition (U:2 individuals), and both mussel and plant addition (PU: the same quantity as used in each treatment). The experiment was conducted in triplicate during 7 days. pH, dissolved oxygen (DO), electric conductivity (EC), salinity, cyanobacterial cell density, chlorophyll-${\alpha}$ concentration, and mussel filtering rate were monitored daily. At the end of the experiment, total phosphorus (TP), total nitrogen (TN), and plant height and weight were measured. Overall, a large degree of cyanobacterial growth inhibition appeared in both P and U treatments, and the effect was highest in the U treatment, followed by P and PU. The combined treatment of both U and P did not show any synergic effects compared to the effect in separated treatment. In all enclosures of the treatments chlorophyll-${alpha}$ (Chl-${alpha}$) concentration decreased until 36 hours after the additions of the plants and mussels. In contrast, Chl-${alpha}$ concentrations increased in PU enclosures after 36 hours. The same trend was shown in the cell density of Oscillatoria. pH and DO gradually decreased until 120 and 144 hours, respectively, in the P and PU enclosures. TP concentration increased in the mussel enclosures (U and PU), while TN concentration largely decreased in the plant enclosures (P and PU). Our results suggest that applied bivalve (Unio) and submerged plant (Potamogeton) seemed to have a potential effect on the growth inhibition of cyanobacteria, but their combined application may have an antagonistic effect to diminish the degree of the inhibition.

• Culinary science and hospitality research
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• v.18 no.3
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• pp.163-179
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• 2012

This study was prepared to develop American sauce with different amounts of salt through high pressure extraction and examined difference in its mechanical and sensory characteristics. Furthermore, it aimed to provide practical materials for the mass production of American sauce and other crustacean sauce products and to contribute to the development of products with superior quality and functionality by standardizing traditional cooking techniques in the food service industry. In American sauce, salt content did not have a significant effect on water content and ash content but had a significant effect on color, pH and salinity. Na and K contents increased with increasing salt content. In addition, Mg and P contents were highest in J4 containing 0.4% of salt, but they did not show any regular tendency according to salt content. For total free amino acids, 29 kinds were detected in J0 and J1, 30 in J2, 31 in J3, and 33 in J4. Detection was highest in J3 containing 0.3% of salt, and the content level was highest particularly for arginine among essential amino acids, for glutamic acid, alanine, serine, ${\beta}$-alanine and ${\alpha}$-aminoadipic acid among flavor enhancing amino acids, and for ${\gamma}$-Aminoisobutyric acid among other amino acids. We measured lipid peroxidation in American sauce using lipid extracted from a mouse brain and confirmed that the amount of antioxidant substances extracted was largest in J0 containing no salt. The results of measuring lipid peroxidation and DPPH showed that the antioxidant effect was high when salt was not contained. In the results of the sensory test, overall quality was highest in J3 containing 0.3% of salt, showing that the addition of salt affects the evaluation of overall quality. Summing up the presents of this study as presented above, we cannot expect an effect of antioxidant functionality; however, according to the results of the mechanical quality evaluation and the sensory test, American sauce containing 0.3% of salt is considered the optimal product in terms of quality. Using these results as practical materials for the mass production of crustacean sauce products, we expect to standardize traditional cooking techniques in the food service industry and to develop products with high quality and functionality.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.1
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• pp.66-69
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• 2000

The common harpacticoida copepod species Tigriopus japnnicus was often obseued in the mass culture of marine rotifer tanks of sea farming stations. In this study, we investigated the co-existing effect of T. iaponicus to the rotifer Brachionus rotundiformis population growth. The culture conditions as temperature, salinity, culture volume, photo period, culture period and observation interval were 25{\circ}C, 22ppt, 40ml, 12L:12D, 16 deys$ and every two days during the experimental period, respectively. Nannochloropsis oculata was used as the food for the two testing organisms. After counting the growth of rotifer and copepod, they were transferred to new culture tank with N. oculata at the density of $7{times}10^5\;cells/ml$. The population growth of B. rotundiformis was suppressed by T. japonicus when these two organisms were mix-cultured comparing to single culture of B. rotundiformis. But population growth of T, japomcus was not affected by the presence of B. rotundiformis. The interspecific relationships of prey-predation and food competition were not observed in the combination culture of rotifer B. rotundiformis and copepod T japonicus.

• Food Science and Preservation
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• v.16 no.6
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• pp.915-923
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• 2009

For preparation of high-quality salted mackerel using enzymatic extracts from Ecklonia cava (EEC) to process fresh mackerel caught off Jeju Island, the optimal concentration of EEC was investigated. There were no differences in proximate composition, salinity, Escherichia coli level, pH, volatile basic nitrogen content, histamine level, or peroxide value between salted mackerel samples prepared with different concentrations of EEC. However, the antiradical properties of salted mackerel, assayed by scavenging of DPPH free radicals, hydroxyl radicals, hydrogen peroxide, and alkyl radicals, increased with increasing concentrations of EEC. The optimal concentration of EEC for preparation of high-quality salted mackerel was 2% (w/w). Salted mackerel soaked in 2% (w/w) EEC was superior to commercial salted mackerel in antiradical properties, biogenic amine content, and other relevant chemical properties.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.4
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• pp.227-234
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• 2009

Using a finite volume ocean circulation model based on an unstructured grid (FVCOM), we studied the structure of a fresh water bulge that influences on the Region Of Freshwater Influence. Fresh water discharged a river forms a coastal boundary current to the righthand side and a cyclonically circulation freshwater bulge that grows with time. In the middle of the bulge, vertical motions bring fresh water to the bottom. When tidal motions are included, the bulge disappears while the boundary currents becomes wider. Through a simple comparison of areas occupied low salinity water we quantified vertical and horizontal mixing due to the tide and showed that the tidal motion enhances the vertical mixing. During the first few tidal cycles right after the onset of the river discharge, due to tidal excursion the horizontal mixing becomes stronger. The vertical mixing by the tide mixes the fresh water After a certain time the water around the river mouth is well mixed and the horizontal excursion of the fresh water near the river mouth does not have much effect on the horizontal mixing. When there is no tidal motion horizontal mixing is mainly by the inertial instability at the surface and the horizontal mixing becomes stronger over time.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.5
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• pp.860-866
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• 2015

Three types of Korean style fried rice sauce, 'Kimchi-tomato sauce', 'Doenjang butter sauce', and 'Seafood sauce' were developed in this study. Physicochemical properties such as pH, soluble solid content, acidity, salinity, and texture of sauces were analyzed after application of three different sterilization conditions ($110^{\circ}C/50min$, $115^{\circ}C/30min$, and $121^{\circ}C/20min$). However, no trend was observed in physicochemical properties of each sauce by sterilization conditions. The lightness (L-value) of doenjang butter sauce was higher than the other two sauces. Redness (a-value) and yellowness (b-value) of doenjang butter sauce and seafood sauce were greater than those of kimchi-tomato sauce due to different ingredients. Total viable cells were not detected under all sterilization conditions of the three types of sauce. The sensory evaluation results showed that $121^{\circ}C/20min$ of sterilization scored better than $110^{\circ}C/50min$ or $115^{\circ}C/30min$ sterilization in terms of overall preference of kimchi-tomato sauce and doenjang butter sauce. Overall, the preference of the three types of sauce showed that seafood sauce was best, followed by doenjang butter sauce and kimchi-tomato sauce.