• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.223-231
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• 1999

Carotenoid pigments of echiurid, Urechis unicinctus were investigated during March, April and May as a part of comparative biochemical studies of carotenoid pigments for the marine organisms other than pisces. Total carotenoid contents were found to be 1.19 mg/100 g in March, 0.98 mg/100 g in April and 0.84 mg/100 g in May, indicating that total carotenoid content was negatively affected by the temperature of sea water that echiurid resided. The carotenoid isolated in March composed of $16.3\%$ diatoxanthin monoester, $14.8\%$ $\beta$-carotene and $12.6\%$ cynthiaxanthin monoester, $8.4\%$ cynthiaxanthin diester, $8.2\%$ zeaxanthin monoester, $7.3\%$ diatoxanthin diester $4.2\%$ astaxanthin $2.9\%$ diatoxanthin, $2.4\%$ triol, $2.3\%$ cynthiaxanthin, $1.7\%$ isocrytoxanthin, $1.5\%$ zeaxanthin diester, $0.8\%$ zeaxanthin and $0.5\%$ lutein. The carotenoid isolated in April composed of $21.9\%$ diatoxanthin monoester, $17.2\%$ cynthiaxanthin monoester and $16.6\%$ $\beta$-carotene $10.9\%$ zeaxanthin monoester, $5.6\%$ cynthiaxanthin diester, $4.9\%$ diatoxanthin diester, $3.1\%$ astaxanthin, $2.4\%$ triol, $2.3\%$ diatoxanthin, $1.7\%$ isocrytoxanthin, $1.5\%$ lutein, $1.1\%$ zeaxanthin, $1.0\%$ cynthiaxanthin and $1.0\%$ zeaxanthin diester. Similarly, the carotenoid isolated in May composed of $25.3\%$ diatoxanthin monoester, $19.7\%$ cynthiaxanthin monoester, $13.0\%$ $\beta$-carotene, and $12.6\%$ zeaxanthin monoester, $5.8\%$ cynthiaxanthin diester, $5.1\%$ diatoxanthin, $3.0\%$ astaxanthin, $2.4\%$ triol, $2.2\%$ diatoxanthin, $1.3\%$ isocrytoxanthin, $1.2\%$ zeaxanthin, $1.1\%$ zeaxanthin diester, $1.0\%$ lutein and $0.9\%$ cynthiaxanthin. Based on these data, monoester-type carotenoids ($37.1\~57.6\%$) and diester-type carotenoids ($11.5\~17.2\%$) of total carotenoids in echiurid were the major carotenoids. Meanwhile, when the sea water temperature was elevated and the contents of total carotenoid in echiurids were decreased, the contents of zeaxanthin monoester, diatoxanthin monoester and cynthiaxanthin monoester were increased, but the contents of zeaxanthin diester, diatoxanthin diester and cynthiaxanthin diseter were decreased, indicating that changes in ester-type caroteoids were differently affected by the sea water temperature.

• Journal of Food Hygiene and Safety
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• v.37 no.6
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• pp.400-410
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• 2022

This study was performed to analyze the microbial contamination levels of three non-heated rice cake manufacturers in terms of seasonal manufacturing process and to investigate the effects of summertime soaking on contamination levels and temperature-controlled soaking in water on reduction in microbial levels. The total aerobic bacteria (TAB) ranged from 2.69 log CFU/g to 5.08 log CFU/g in the produce, but the microbial contamination increased sharply during soaking. The levels of TAB and coliforms during summer soaking were 7.01 and 3.96 log CFU/g, respectively, and this was significantly higher than those in other seasons. The contamination level was high in the subsequent freezing, with the TAB level (6.24 log CFU/g) exceeding the legal standard. The temperature of soaking water in summer increased from 19.1℃ to 26.8℃ after 12 h of soaking. The microbial contamination was significantly high commensurate with increased soaking time, and the TAB level in the frozen process exceeded the legal standard from 9 h of soaking. The use of ice packs to prevent the increase in temperature of the soaking water in summer resulted in maintenance of temperature at 20.1℃ for up to 12 h. The average TAB value in the freezing process was 4.42 log CFU/g after 12 h of soaking, and this is 1.77 log CFU/g lower than that before. Based on these results, it was determined that controlling the soaking time and water temperature are essential for the production of a safe unheated frozen rice cake. The safety of the HACCP system could be established by applying these preventive management standards.

• Korean Journal of Ichthyology
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• v.17 no.1
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• pp.64-72
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• 2005

The data for the present study were collected from the both-sides fyke net fishery in coastal Dolsan, Korea, from March 2003 to February 2004 A total of 2,402 individuals (432,42 kg) were collected and identified to 11 orders, 34 families, and 48 species. The most dominant order was the Perciformes, comprising 21 species in 15 families, followed by Scorpaeniformes, 8 species in 5 families, and Pleuronectiformes, 5 species in 3 families, These three orders constituted 67.9% of the total collected fish. The most dominant species, Acanthopagrus schlegeli, accounted for 279 individuals (20.26 kg), followed by Mugil cephalus with 187 individuals (99.61 kg), and Konosirus punctatus with 178 individuals (8.89 kg). The diversity index of the fish catches was 1.6823~2.9105 and was the highest in September 2003 and the lowest in December 2003. The evenness index was 0.6585~0.8872 it was the highest in August 2003 and the lowest in December 2003. The dominance index was 0.2000~0.6852, with the highest in December and the lowest in August 2003.

• Journal of Wetlands Research
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• v.17 no.3
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• pp.320-324
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• 2015

This study was executed to know the effect of three differently controlled temperature conditions on Huanren brown frog (Rana huanrensis )'s growth in 2013. We've collected nine Huanren brown frog egg's sacs on Mt. Surak ($37^{\circ}40^{\prime}55.86^{{\prime}{\prime}}N$, $127^{\circ}05^{\prime}19.99^{{\prime}{\prime}}E$) in Seoul. We put those nine egg sacs in the controlled growth chambers under low temperature (LT, $5{\pm}2^{\circ}C$), medium temperature (MT, $10{\pm}2^{\circ}C$), and high temperature (HT, $13{\pm}2^{\circ}C$) conditions with three egg sacs, respectively. We measured the eggs' hatching rate, their hatching periods, and the size of the hatched individuals. The hatching rate was higher in MT (95.6%) and the rates of the other treatments were relatively lower but very similar such as LT (82.2%) and HT (82.6%). The three hatching periods were 10 days at HT, 14 days at MT and 23 days at LT. The body sizes of the hatched individuals were biggest at MT ($7.62{\pm}0.11mm$), smallest at LT ($6.82{\pm}0.10mm$) and medium at HT ($7.19{\pm}0.15mm$) (P-value ${\leq}0.0001$). From our results, we found that the various water temperatures could be very effective to Huanren brown frog eggs' hatch and growth including their body sizes. We suggest if we study more about the growth of Huanren brown adult frogs under similar temperature conditions for a long term period, it must be very helpful for conservation study about metamorphosis rate and size of adult frog as well as we could understand about the amphibians who are adapting to the climate change.

• Korean Journal of Ichthyology
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• v.13 no.2
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• pp.143-157
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• 2001

To determine seasonal fluctuations in abundance and species composition of the fishes, samples were collected by bottom trawl off Kohung Penisula from February to December 1999. A total of 7,197 fishes were sampled and identified into 123 species, 54 families, 13 orders and 2 classes. Of the 13 orders, Perciformes, Scorpaniformes, Pleuronectiformes and Tetraodontiformes accounted for approximately 82.9% of the total. Gobiid fishes were dominant, representing 13 species. Leiognathus nuchalis, Konosirus punctatus, Engraulis japonicus, Ilisha elongata, Trichiurus japonicus, Argyrosomus argentatus, Ditrema temmincki, Takifugu niphobles, Hexagrammos otakii and Lateolabrax japonicus accounted for 71.4% of the number of individuals. Mugil cephalus, Sebastes schlegeli, Lateolabrax japonicus, Konosirus punctatus, Hexagrammos otakii, Conger myriaster, Liparis tanakai, Seriola quinqueradiata, Trichiurus japonicus, Sebastiscus marmoratus and Limanda yokohamae accounted for 50.7% of the total biomass. The number of species showed a seasonal variation, higher in spring, summer and autumn than in winter. The Largest numbers of individuals and greater biomass were observed in August. The economic fishes of this area were Konosirus punctatus, Engraulis japonicus, Mugil cephalus, Sebastes inermis, Sebastes schlegeli, Sebastes oblongus, Sebastiscus marmoratus, Platycephalus indicus, Hexagrammos agrammus, Hexagrammos otakii, Lateolabrax japonicus, Epinephelus akaara, Epinephelus septemfasciatus, Seriola quinqueradiata, Pagrus major, Acanthopagrus schlegeli, Argyrosomus argentatus, Oplegnathus fasciatus, Trichiurus japonicus, Pampus echinogaster, Paralichthys olivaceus, Kareius bicoloratus, Limanda yokohamae and Takifugu porphyreus.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.721-728
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• 2008

DBPs(Disinfection By-Products) are most formed through the reactions between chlorine and NOM(Natural Organic Matter) in water treatment. In this study, occurrence of DBPs including THMs(Trihalomethanes) is evaluated. Also, influencing factors by the seasons and raw water quality were investigated for correlation among them and the characteristics of THMs formation by prechlorination process. This study investigated the operation condition for THMs removal depending on raw water quality. Water treatment plant from intake station to gauging well flows for about 10 hours in Y Water Supply Office. It is limited to control of THMs formation because of excessive reaction time between chlorine and THMs precursors in the intake station. Therefore, as multi-points prechlorination from intake station to gauging well, THMs formation was decreased in the water treatment, and it was willing to prevent overdosage of chlorine. The concentration of THMs was 0.021 mg/L in the summer, 0.015 mg/L in the winter, respectively. Also, THMs formation showed that 0.013 mg/L in the water of gauging well after prechlorination, 0.014 mg/L in the flocculation/sedimentation/filtration, 0.016 mg/L in the water after postchlorination, respectively. THMFP(Trihalomethane Formation Potential) removed 42.7% and 50% through the flocculation/sedimentation and filtration, respectively, and it is similar TOC removal efficiency. In this study, multi-points prechlorination from intake station to gauging well decreases in contact time and concencrations of NOM and chlorine. Also, it decreases in THMs and amount of chlorine uesd. In the result of multi-points prechlorination in the summer, the concentration of THMs was 0.013mg/L in the treated water. In view of these facts, THMs formation can be decreased approximately 50%.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.152-159
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• 2002

The seasonal variations of nitrifying bacterial population sampled from 3 sites in Moon-Chon reservoir were analyzed by in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes from August 2000 until July 2001. In addition, physico-chemical parameters such as temperature, pH, chi-a and DOC were measured to determine correlations between those factors and the size of nitrifying bacterial populations. Total bacterial numbers varied in the range of $0.8{\sim}1.5{\times}10^6\;cells/ml$ independent of sites and had the maximal values in March at all 3 stations. The ratio of eubacteria to total bacteria ranged from 44.9% to 79.5%, and the ratio of each nitrifying bacteria to eubacterial numbers reached only $1.0{\sim}7.4%$. The variations of ammonia-oxidizing bacteria ranged from $1.1{\times}10^4$ to $3.0{\times}10^4\;cells/ml$ without noticeable peak values whereas those of nitrite-oxidizing bacteria varied in $1.3{\sim}5.7{\times}10^4\;cells/ml$ with the increasing tendency in winter regardless of the sites. Moreover it was observed that the numbers of nitrite-oxidizing bacteria were higher than those of ammonia-oxidizing bacteria. Total bacterial numbers correlated with water temperature (r = 0.355, p<0.05) and DOC (r = 0.58G, p<0.01) positively whereas nitrite-oxidizing bacteria correlated with temperature (r = -0.416, p<0.05) and pH (r = -0.568, p = 0.001) negatively. In addition, DOC represented good correlations with eubacterial numbers (r = 0.448, p<0.01). These results indicate that temperature, DOC and pH might be one of the main factors affecting variations of bacterial populations in the aquatic ecosystem. It was also suggested that FISH method is a useful tool for detection of slow growing nitrifying bacteria.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.6
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• pp.511-522
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• 1984

The Nagdong is one of the biggest rivers in Korea, which is very important water source not only for tap water of Pusan city but also for the industrial water. Therefore, authors tried to check the water quality year by year. In this experiment one hundred and twenty water samples collected from August 1983 to July 1984 were analyzed bacteriologically and physiologically. Fifteen sampling stations were established between near Samrangjin and estuary of the river. To evaluate the water quality, temperature, pH, chloride ion, salinity, chemical oxygen demand (COD), electrical conductivity, nutrients, total coliform, fecal coliform, fecal streptococcus, viable cell count and bacterial flora were observed. The variation of water temperature was ranged $-1.5{\sim}29.0^{\circ}C$ (Mean value $13.9{\sim}16.5^{\circ}C$), it in spring was higher as $10{\sim}15^{\circ}C$ about $10^{\circ}C$ than in winter and it in autumm was very stabilized as about $20^{\circ}C$ at each station. The pH variation of the samples was ranged $6.68{\sim}9.15$. The range of concentration of chloride ion and salinity varied $7.4{\sim}l,020.5$ mg/l and $1.05{\sim}33.0\%0$, respectively. Especially, salinity of the 3rd water war was the higher than others as $25.76{\sim}31.58\%0$. COD was ranged $1.45{\sim}14.94$ mg/l and the lower part of the Nagdong River was heavily contaminated by domesitc sewage and waste water from the adjacent factor area. The range of electrical conductivity was $1.360{\times}10^2{\sim}5.650{\times}10^4{\mu}{\mho}/cm$ and that was by far higher the estuary than the upper. Concentration of nutrients were $0.008{\sim}0.040$ mg/l (Mean value $0.019{\sim}0.068$ mg/l) for $NO_2-N,\;0.038{\sim}5.253$ mg/l ($0.351{\sim}2.347$ mg/l) for $NO_3-N,\;0.100{\sim}2.685$ mg/l($0.117{\sim}1.380$ mg/l) for $NH_4-N,\;0.003{\sim}0.084$ mg/l($0.014{\sim}0.065$ mg/l) for $PO_4-P$ and $0.154{\sim}6.123$ mg/l ($1.165{\sim}3.972$ mg/l) for $SiO_2-Si$, respectively. Usually nutrients contents of the water in the upper part(included station 1 to 5) were higher than those of the estuarine area. The bacterial density of the samples ranged 7.3 to 460,000/100 ml for total coliforms, 3.6 to 460,000/100 ml for fecal coliform, $0{\sim}46,000/100ml$ for fecal streptococcus and $<30{\sim}1.2{\times}10^5/ml$ for viable cell count. Composition of coliform was $28\%$ Escherichia coli group, $18\%$ Citrobacter freundii group, $31\%$ Enterobacter aerogenes group and $22\%$ others. Predominant species among the 659 strains isolated from the samples were Pseudomonas spp. ($42\%$), Flavobacterium spp. ($20\%$) and Moraxella spp. ($12\%$).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.3
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• pp.154-163
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• 2005

Irregular discharges of freshwater through the water gates of the Keum River Estuarine Weir, Korea, whose construction had been completed in 1998 with its water gates being operated as late as August 1994, drastically modified the estuarine environment. Sharp decrease of salinity along with the altered concentrations of inorganic nutrients are accompanied with the irregular discharges of freshwater into the estuary under the influence of regular semi-diurnal tidal effect. Field sampling was carried out on the time of high tide at 2 fixed stations(St.1 near the Estuarine Weir and St.2 off Kunsan Ferry Station) every other day for 4 months from mid-February 2004 to investigate into the semi-weekly variation of spring phytoplankton community in relation to the freshwater discharges from Keum River Estuarine Weir. CV(coefficient of variation) of salinity measurements was roughly 2 times greater in St.1 than that in St.2, reflecting extreme salinity variation in St.1 Among inorganic nutrients, concentrations of N-nutrients($NO_3^-,\;NO_2^-$ and $NH_4^+$) were clearly higher in St.1, to imply the more drastic changes of the nutrient concentrations in St.1. than St.2 following the freshwater discharges. As a component of phytoplankton community, diatoms were among the top dominants in terms of species richness as well as biomass. Solitary centric diatom, Cyclotella meneghiniana, and chain-forming centric diatom, Skeletonema costatum, dominated over the phytoplankton community in order for S-6 weeks each (Succession Interval I and II), and the latter succeeded to the former from the time of <$10^{\circ}C$ of water temperature. Cyanobacterial species, Aphanizomenon Posaquae and Phormidium sp., which might be transported into the estuary along with the discharged freshwater, occupied high portion of total biomass during Succession Interval III(mid-April to late-May). During this period, freshwater species exclusively dominated over the phytoplankton community except the low concentrations of the co-occurring 2 estuarine diatoms, Cyclotella meneghiniana and Skeletonema costatum. During the 4th Succession Interval when the water temperature was over $18^{\circ}C$, the diatom, Guinardia delicatula, was predominant for a week with the highest dominance of $75\%$ in discrete samples. To summarize, during all the Succession Intervals other than Succession Interval III characterized by the extreme variation of salinity under cooler water temperature than $18^{\circ}C$, the diatoms were the most important dominants for species succession in spring. If the scale and frequency of the freshwater discharge could have been adjusted properly even during the Succession Interval III, the dominant species would quite possibly be replaced by other estuarine diatom species rather than the two freshwater cyanobacteria, Aphanizomenon flosaquae and Phormidium sp.. The scheme of field sampling every other day for the present study was concluded to be the minimal requirement in order to adequately explore the phytoplankton succession in such estuarine environment as in Keum River Estuary: which is stressed by the unpredictable and unavoidable discharges of freshwater under the regular semi-diurnal tide.

• The Korean Journal of Malacology
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• v.32 no.2
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• pp.95-102
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• 2016

This study investigated the growth characteristics of juvenile abalone when has been rearing as other different feed rates by the commercial abalone formulated feed on indoor tank, during the winter period that was maintaining on the low water temperature. Experimental abalones were use to 1 year old (shell length $29.14{\pm}2.56mm$, wet weight $2.9{\pm}0.6g$), and it has cultured at six feeding rate groups (0.75 DFW, 1.50 DFW, 2.25 DFW, 3.00 DFW, 3.75 DFW, 4.5 DFW) that were set up the daily feeding rate about total weight (DFW), and two replicated. The average water temperature in the experiment period was $9.7{\pm}3.27^{\circ}C$. In the monthly change absolute growth rate (AGRSL) and specific growth (SGRSL) of shell length, at January, 3.00 DFW was significantly higher than all feeding rate groups (P < 0.05). And in the monthly change of weight change and weight gain (WG), at March, 3.75DFW was significantly higher than all feeing rate groups (P < 0.05). The growth coefficient of thermal units (TGC) was decreased rapid since January, and 3.75 DFW was show significantly higher than all feeding rate groups (P < 0.05). In monthly change of feed efficiency (FE), at December, the 0.75 DFW was significantly higher than all feeding rate groups (P < 0.05), and in February and March, there was no significant difference between all feeding period. Therefore, In this study, was show that juvenile abalones can do to maintain or increasing from weight to supply commercial artificial diet during winter period when rearing into the indoor tank.