• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.3
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• pp.117-123
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• 2006

The water quality before and after a typhoon was investigated as a part of a study on the increase of organic matter and on the fundamental measures to counter chemical oxygen demand (COD) in the eutrophic Soho coastal seawaters of Gamak Bay. The dissolved oxygen (DO) saturations were <54% when water column was stratified. The DO saturation was similar at surface and in the bottom layer after a typhoon $(78\sim88%)$, and a very high DO saturation (234%) was observed in the surface water after mass phytoplankton growth. The highest values of $NH_4-N,\;NO_3-N,\;PO_4-P$, and $SiO_2-Si$ were 18.22, 38.90, 1.58, and $52.10{\mu}M$, respectively, when freshwater entered after heavy rainfall events. In addition, high concentrations of $NH_4-N,\;PO_4-P$, and $SiO_2-Si$ were detected with low DO saturations in bottom water (>5m). A maximum chlorophyll (Chl.) concentration of $311.0{\mu}gl^{-1}$ was observed after typhoon, when a high-density Scrippsiella trochoidea red tide occurred with cell density of 42,000 cells $ml^{-1}$. The algal growth potential (AGP) was high after the typhoon. Nitrogen was always a limiting nutrient for phytoplankton growth. The highest COD level was $10.55mgl^{-1}$, and the main reason of the variation in COD was likely to be phytoplankton growth $(r^2=0.612,\;p=0.000)$. Organic matter, which entered the water column when the typhoon stirred the sediments, seems to have little effects on COD increase.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.3
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• pp.163-170
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• 2009

Several species of the genus Pseudo-nitzschia produce the neurotoxin domoic acid (DA) known to be responsible for amnesic shellfish poisoning. In spite of the potentially toxic effects on marine ecosystem, even the representative Pseudo-nitzschia species occurring in Korean coastal waters have not been clearly reported. Plankton samples from several outer coastal sites of Tongyeong were collected fortnightly from May to November 2008 and the presence of diatoms of the genus Pseudo-nitzschia was examined using light and scanning electron microscopy. Thirteen species were observed, including P. americana, P. brasiliana, P. caciantha, P. calliantha, P. cuspidata, P. delicatissima, P. micropora, P. multiseries, P. multistriata, P. pseudodelicatissima, P. pungens, P. subfraudulenta, and P. subpacifica. The number of Pseudo-nitzschia species observed were only four in May, which was minimum during this survey, and then gradually increased attaining maximum, twelve, in September. After September it began to decrease again and got to five in November. Of these, P. americana, P. brasiliana, P. caciantha, P. calliantha, P. micropora, and P, pseudodelicatissima are new records for the Korean coastal waters and P. calliantha, P. cuspidata, P. delicatissima, P multiseries, P. multistriata, and P. pungens have been reported as DA producers around the world, but the potential toxicity of these species was not ascertained in Tongyeong area.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.1
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• pp.57-69
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• 2001

The chemical, elemental and biochemical components of the suspended particulate matter (SPM) were investigated in order to quantify particulate organic matter (POM) and assess diet quality for suspension feeders in the southern coastal bay systems of Korea where the marine farming of the suspension feeders are most active, The intense field observation program was carried out seasonally in the three coastal bay systems of Chinhae, Gosung and Kangjin bays, The SPM was characterized as collective properties of organic carbon (POC), nitrogen (PON), phosphorus (PP) and more refined collective properties of protein (PPr), carbohydrate (PCHO) and chlorophyll a (Chl a) compound. Although the three coastal bays are regarded as phytoplankton based ecosystem, the SPM is not composed entirely with phytoplankton cells. Due to the shallow water depth, resuspension of bottom sediment contributes significantly to some of the regions. Therefore, concentration of SPM in the surface water did not co-vary with Chl a or PPr, PCHO. In general, temporal variation of POC, PON and Chl a contents in seawater were closely associated with phytoplankton biomass in the three coastal bays, However, PPr and PCHO contents in seawater were higher in Chinhae bay than in Gosung and Kangjin bays and Chl a PPr-N ratio was higher in Chinhae bay than in Kosung and Kangjin bays, since Chinhae bay is more eutrophicated than other bays. Average C : N ratios from regressions of POC and PON of SPM were 6.6, 6.6 and 5.0 in Chinhae, Gosung and Kangjin bays, respectively. SPM in Chinhae and Gosung bays appears to be made of largely phytoplankton cells and SPM in Kangjin bay appears to be contributed from the bacterial biomass due to the shallow water depth. N : P ratios from regressions of PON and PP of SPM were 10.8 and 14.7 in spring, and 18.2 and 24.6 in Chinhae and Gosung bays, respectively. With respect to the hypothetical Redfield molecule, phytoplankton appears to be limited by the lack of N and f in spring and summer, respectively, in the two bays, In Kangjin bay, N : P ratios from regressions of PON and PP of SPM were varied from 6.3 to 12.8 throughout the year. The low N : P ratio with resepct to the hypothetical Redfield molecule, phytoplankton growth appears to be limited by the lack of N-nutrients.

• The Journal of Fisheries Business Administration
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• v.4 no.1_2
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• pp.19-57
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• 1973

Laver io one of the most necessary and seasonal items in Korean food from oldtimes. Laver is lagely eaten in dried form, and its supply depends entirely upon culture weeds. The history of laver culture in Korea about sixty or seventy years is older than in Japan. Significance of laver culture is divided into two aspects, one is food supply in the nation, and the other is export to other countries. Houses engaged in laver culture are about foully thousands, and laver production in 1972 is estimated as 1, 3 bitten sheets. (1 sheet is a dried laver of 20 cm sq, in the shape of paper) Especcially meaning of layer production is the concentration of labour input, and systematic management of labour. From around 1920, the method of laver culture was introduced by Japanese Imperialism for mono culture in shallow seas, and mass products of laver is provided to Japan market, DOMESTIC MARKET Fundamental consume function calculates at below, $D_{(68_71)}$=16354 $Y^{0.471}$ $P^{-1.0662}$ where D is total layer demand, Y income variable, P price variable. It means income elasticity is 476. in the whole country, and price elasticity is 1, 07. But generally income elasticity is higher in urban area than in rural area, as shown at 1, 3 in Seoul city. Expence of laver in house expenditure is mutually correlated with another expence, See Table 12 about the relative function. See Table 14 and 16 about the relation between the gathering and the changes of price in auction, wholesale and retail price support system is for two effects, one of which is constraint of the upper price, the other is rise of the lower price. Before the system control, the equation in three year average calculated as below, $Y_{b}$ ＝18, 907.7455＋15435.9364 t (r=0.89) where the origin t＝0 is the November and the units are month. Post the system control, $Y_{p}$ =30, 047.9636+1, 631.1721t (r＝0.97) therefore, this system has an effect only on the rise of lower price, Average annual margins of laver products at four market levels according to the consumer spent is below. EXPORTING MARKET Japanese demand function of laver products is, Log D=5, 289+1, 108 Log Y-1, 395 Log P (r=0.987) where D is Japanese laver demand, Y income variable, P price variable. according to which income elasticity is 1. 1 and price elasticity is 1.4. Laver production in 1970 tile highest record till then, is estimated as six billion sheets. But the recent improvement of laver culture techniques, the production of seeds and freezing storage of seeds has been stabilized. Futher new culture farms have been developed by means of break- water fences or by floating culture method. These improvements have been backed up with increased demand of laver products. Import quantity and price of Korean laver products are restrained by three organizations, that is producer, distributor and consumer. This relationship calculated by regression equation shows that import is influenced only producer organization, at the sacrifice of consumer profit. For increase to export of laver products, we urgently require to open foreign trade of laver products for Japanese consumer, .and Japan has political responsibility to solve Korean laver structure. But with long run timeseries, as regards Japanese production and import quantity, importing function shows increasing trend as below, 250 million sheets ＜3, 947.1674+0.005 $L_{g}$ ＞) 600 million sheets where $L_{q}$ is relative production quantity of laver in Japan. (unit; 100 thousand sheets) Our Export effort should be put on the highly processed products whithin the restraind quote.ote.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.2
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• pp.90-100
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• 1975

The estimation of the pre-processing condition of oyster is of great importance for distributors and processors. This study was attempted to establish the basic data for evaluating the processing suitability of oyster, which is the most important shellfish for domestic use and export. The data were analysed by measuring the condition index, chemical composition and heavy metal content of oysters. In order to eliminate the manual work that has to be done on a tightly closed oyster shell and avoid shrinkage in the oyster meat which is attendant on the steaming process, chemical means to open oyster were examined. finding the method of pretreatment of polyphosphate for frozen oysters were attempted to improve the product quality. The prevention of undesirable color change of the canned oyster meat is another problem to solve. The important results are as follows : 1. The ratio of meat volume and meat weight to the holding capacity by shells may be useful as an index to measure the condition index of oysters. 2. As a whole, monthly changes of moisture and fat content in oysters were reversely correlated. Protein content slightly decreased from April and rapidly decreased in July, and again rapidly increased in August but from September to November decreased slightly. In April, the content of glycogen was 4 percent. From this period to September, glycogen was rapidly decreased. From July to September, it was only 0. 7 to 1 percent but increased from October. There were little seasonal changes in pH value. The pH value of oyster meat was 6.0 to 6.2. The crude ash content was slightly decreased from June to August. 3. The range of monthly change of heavy metal content are as follows: Total mercury was 0 to 0.019 ppm, cadmium was 0.026 to 0.053 ppm, copper was 0.111 to 0.594 ppm, and lead_was 0.061 to 0.581 ppm. 4. By the results of condition index, chemical composition and heavy metal content of oysters, the suitable harvest season as raw materials for processing was the end of December to the end of May of next year. 5. The pretreatment of 10 percent polyphosphate in 5 percent salt solution of oyster meat appeared effective to reduce thawing drip during cold storage. 6. The pretreatment of $Na_2EDTA$ and BHA did not show the color prevention effect to the canned oyster meat during storage. 7. Magnesium chloride affected to open the valves of oysters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.1
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• pp.17-26
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• 2005

There are several problems in the commercial pound net in the heavy tide ; the breaking and loss of net, steeply variation of net shape and decreasing of fishing efficiency, etc. In order to solve these problems, we introduced method of added sinker used to coastal cultivating cage of Japan and investigated the possibility of application to the Korean pound net. The results are obtained as follows; 1. In case of the upperward flow with fish court net, tension of the frame line was increased about 10${\sim}$25% than that of prototype according to the added sinker from 1.3gf to 5.2gf. The tension of A-type and B-type was similar to the case of the prototype, the tension of C-type and D-type was increased about 10${\sim}$15% than that of prototype. 2. The variation of deformed angle of fish court net was from 0$^{\circ}$ to 70$^{\circ}$ and that of the slope net was from 0$^{\circ}$ to 64$^{\circ}$ and that of the second bag net was from 0$^{\circ}$ to 46$^{\circ}$ and the depth of the second bag net was increased about 10% when the added sinker was changed from 1.3gf to 5.2gf. The depth of the first bag net and the second bag net were decreased about 50% than that of initial depth. 3. For the deformed angle of fish court net according to the attached point of the added sinker, A-type and B-type were decreased about 25% and 10% than the prototype, respectively. C-type was similar to the case of the prototype and D-type was increased about 15% than that of the prototype. The depth of slope net became deep in turn of A-type, B-type, C-type and D-type. For the depth of the second bag net, A-type, B-type, C-type and D-type were increased about 10${\sim}$15% than that of prototype. The depth of the slope net was changed from 0$^{\circ}$ to 63$^{\circ}$ and that of the second bag net was changed from 0${\sim}$44$^{\circ}$ according to the increase of velocity. 4. The optimal weight of added sinker was about 2.6${\sim}$3.6gf and the optimal attached point of added sinker was the case of C-type and D-type.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.3
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• pp.154-160
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• 1989

To obtain basic data on food components of triploid fish, we undertook the analysis of free amino acid, nucleotide, total creatinine, betaine, trimethylamine oxide(TMAO) and their related compounds in diploid and triploid carps(Cyprinus carpio). The contents of total free amino acid and its related compounds in belly and dorsal muscles of triploid carp were 346.1mg/100g and 333.4mg/100g. Histidine occupied $45.1\%\;and\;46.9\%$ in belly and dorsal muscles, and followed by taurine, lysine and glycine in order. As for the compositions of nucleotide and its related compounds in those muscles of triploid carp, IMP were revealed $73.9\%\;and\;65.8\%$ of total nucleotide and its related compounds. The major component of the other organic base in those muscles of triploid carp was total creatinine, but betaine and TMAO were poor. The contents of taste compounds such as free amino acid, nucleotide, total creatinine, betaine, TMAO and their related compounds were less in triploid carp than in diploid carp of nonspawning season, while were more in triploid carp than in diploid carp of spawning season. Total amino acid contents were more in diploid carp of nonspawning season than in triploid carp, but mineral contents were more in triploid carp than in diploid carp of spawning season. Therefore, it is believed that triploid carp is very worthy for a tasty and nutritional food source.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.267-273
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• 1977

Rainbow trout were reared in a small indoor aquarium which was equipped with a simple recirculating biofilter combined with a small amount of inflowing water for 199 days from April 25 to November 10, 1977 in Busan where very hot summer air temperature is encountered, and results obtained were promissing as following; 1. The aquarium has dimensions of $1m\;\times\;1m\;\times\;67cm(depth)$, and a bottom center sedimentation chamber of conical type through which out-flowing water is pushing fecal matter and other detritus outward. The conical sedimentation chamber measures 20 cm depth and 20 cm diameter at its upper mouth and tapers to the bottom end which is connected to 4 cm diameter draining pipe. The draining pipe goes through under the tank and then is elevated on the side. The water depth was maintained at about 40 cm depth by adjusting the heigh of draining pipe. The filter bed contained 16 l of $3\~5\;mm$ zeolite gravels, and water circulation rate was about 1030 l/hr. 2. Continuous inflowing water resulted in a good elimination of waste materials through its outflowing water thus reducing waste loading in the filter. 3. Mean temperature of water in the rearing aquarium containing about 400 l water volume was maintained at around 20 to $22^{\circ}C$ by 0.59 l/min of the inflowing well water which usually maintained the temperature of $17^{\circ}C$ during the hot summer season from the first of July to the first of October when the 10-days-mean air temperature ranged from $20^{\circ}\;to\;27.3^{\circ}C$ $(total\;mean\;24.6^{\circ}C) $ and under this condition the fish continued normal growth. 4. The production per 1 l/min of inflowing water with this simple biofilteration reached 30 hg. 5. The total cost including all feed and power during this experimental rearing period fell well within the economic establishment and if the feed and filteration system are improved the benefit-cost ratio will be much increased.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.423-428
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• 1998

The effective extraction methods and chemical components of crude polysaccharides of ascidian tunics were investigated. Tow extraction conditions, autoclaving or enzyme treatment, were applied. The proximate composition of ascidian tunics was not much different between those dried in raw (containing pigments) and those acetone treated and dried (decolorized), showing $50\%$ of carbohydrate and $40\%$ of protein. It was possible to extract up to $10\%$ of crude polysaccharides from ascidian tunics regardless of the extraction methods, autoclaving or enzyme treatment. In case of the latter the extraction yield by neutrase was higher than that with alkalase (Novo co.) or mixture 2000 (Pacific chemical co.). The most effective enzyme concentration and extraction time appeared to be 24 hrs of extraction with $3\%$ neutrase. On the other hand, in autoclave treatment, 6 hrs extraction showed most desirable extraction yield, about $9.7\%$. The compositions of amino acid of decolorized ascidian tunic (acetone treated group) and the crude polysaccharide from the autoclaving (water solubles) or neutrase treatment (enzyme digestibles) were similar to each other. Histidine was the highest both in the neutrase and autoclave treatment group and the yield were $29.2\%,\;20.4\%$, respectively, followed by aspartic acid and glutamic acid. Among the minerals, the content of Ca was significantly high, followed by Mg and Na.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.429-436
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• 1998

A bacteriological study of sea water and oyster in Charan Bay was conducted to evaluate sanitary conditions of the bay and compliance of waters with the recommended bacteriological criteria for the designated area of shellfish cultivation, The Samples were collected at 23 sampling stations(Fig. 1 and Fig. 2) estaslished once a month from January 1997 to December 1997, During the study period, temperature ranged from 4.7 to $25.6^{\circ}C$, transparency ranged from 3.3 to 6.2m chemical oxygen demand ranged from 1.67 to 2.18 mg/$\ell$, dissolved oxygen demand ranged from 5.4 to 10.0 mg/$\ell$ dissolved nitrogen ranged from 1.65 to 7.88 $\mu$g-at/$\ell$, phosphate ranged from 0.15 to 1.16 $\mu$g-at/$\ell$, Chlorophylla-a ranged from 0.95 to 12.69mg/$\ell$. The coliform group and fecal coliform MPN's of sea water were ranged from <1.8$\~$l,600 and <1.8$\~$540, respectively. The coliform group and fecal coliform MPN's of oysters were ranged from <18$\~$16,000 and <18$\~$1,400, respectively. The viable cell counts in oyster ranged from $1.5\times10^2$ to $7.5\times10^3$. The bacteriological criteria of sea water in shellfish growing area should be less than 70 per 100 ml of sea water for median value of coliform MPN, and below $10\%$ of the samples which contain over than 230 for coliform MPN or over than 43 for fecal coliform MPN. The sea water from 432 samples were complied water coliform criteria recommended for designated shellfish growing area. The coliform group, fecal coliform, classification of coliform group with IMViC reactions and pathogenic vibrios were analyzed. During the study period, infectious bacteria such as Vibrio cholerae, Salmonella sp, and Shigella sp, were not detected from the samples, but detection ratios of Vibrio parahaemolyticus and Vibrio vulnifirus were $7\~17\%$ in summer months.