• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.237-246
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• 2002

Tamjin Dam is built in the upper reaches of the Tamjin River which flows through the Janghung-gun and Gangjin-gun of the Jeollanamdo, Korea. In order to map out a preservation strategy of the fish community from dam construction, We studied the distribution of fish distribution and changes of the habitat environment. we found 49 fish species inhabiting in the downstream and upstream of the Tamjin Dam. Among them, migratory fish were two species sweet smelt, Plecoglossus altivelis and freshwater eel, Anguilla japonica. The Coreoperca kawamebari which designated as a species to be protected by The Ministry of Environment of Korea was also observed. After the dam construction, reservoir would be filled with water and running water system will change to standing water system. Then the habitat and spawning space for mountain torrent fish will be reduced and the migration of migratory fish to upstream will be blocked. Through our study, we proposed several ways to protect fish community. In order to preserve the reduced habitat and spawning area of mountain torrent fish, a fishway has been diagnosed to be built in the shallow reservoir in the entrance of the upriver. The establishment of artificial spawning ground on the riverside has been recommended. In addition, We propose a creation of a shelter for fresh water eel, Anguilla japonica in areas where the depth of the water is about l0m by laying rocks. Since it is difficult for a spawning ground to be formed naturally in the reservoir due to the year-round changes in water level, We suggested a floating spawning facility using an artificial fixture. In the downstream of the dam, a waterway-style habitat and spawning ground in the river and increasing the diversity and abundance of fish fauna in the Tamjin River. A low-cost and highly efficient operational fishway has been recommended so that migratory fish such as Plecoglossus altivelis (sweetfish) can migrate from the lower reaches to the upper reaches of the river.

• Korean Journal of Ecology and Environment
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• v.35 no.3 s.99
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• pp.160-171
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• 2002

The impact of summer monsoon on water quality of the lower Nakdong River was evaluated during the summer (June-August) in 1997. Several limnological variables were measured in the interval of $1{\sim}3$ day using an automatic monitoring system (Hydrolab $Recorder^{TM}$) to detect water quality changes caused by rainfall on onehour basis. During the monsoon period (from late June to mid July), 5 times of major rainfall events of >50 mm were recorded in the river basin. Dynamic changes of water quality were observed during the monsoon, and the first rainfall event (June$25{\sim}27$) had a significant influence on the water quality at the lower part of the river. All Parameters were largely changed due to the first rain event, and the changed level was maintained until the end of monsoon period. Nutrient concentrations and turbidity increased and values of the other parameters were declined as a result of water dilution. This rainfall event, Changma, is a meteorological phenomenon caused by the East-Asian monsoon climate. The magnitude and frequency of the rainfall during the early monsoon play an important role in change of water quality and ecosystem characteristics of large river systems.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.319-331
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• 2004

This study was conducted to evaluate the ecological impact of freshwater bivalve (Corbiculidae) on plankton communities in experimental enclosure systems (2 m ${\times}$ 2 m ${\times}$ 2 m). During the acclamation period of one month, cyanobacteria, including Microcystis viridis and Microcystis aeruginosa, dominated in both control and treatment enclosures with no noticeable density difference. After the addition of 100 mussels, dominant species of phytoplankton shifted from Microcystis to Scenedesmus in concert with slight decrease in the cell density and the increase of N/P ratio. However, cell density in the control quickly increased, accompanied with changes of dominant species to Oscillatoria spp. With the introduction of additional 500 musseles in the treatment enclosure, dominant phytoplankton species in both enclosures were replaced with Selenastrum spp. and Cryptomonas sp. In the initial stage, the total zooplankton abundance in the control was higher than that of treatment, but it was reversed after the addition 100 mussels. After mussel density increased up to 600 indivisuals, zooplankton density in the treatment decreased with dominance of small taxa, such as rotifers and nauplius. However, abundance and carbon biomass of large zooplankton, such as Bosmina longirostris and Diacyclops thomasi were maintained in a high level compared with those of control. During the study period, Chl. a concentration in mussel treatment and control increased with DIP and $NH_3-N$, respectively. Due to the increase of $NH_3-N$, especially after the introduction of additional 500 mussels, nitrogen limitation did not occur in the treatment enclosure in contrast with strong nutrient limitation occurred in the control. These results indicate that filter-feeding Corbicula could exert important impact on nutrient recycling and plankton community structure in a freshwater ecosystem, through direct feeding and competition for the same food resource as zooplankton on one hand, and through alteration of nutrient availability on the other.

• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.147-152
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• 2015

Nitrogen (N) loading from domestic, agricultural and industrial sources can lead to excessive growth of macrophytes or phytoplankton in aquatic environment. Many studies have used nitrogen stable isotope ratios to identify anthropogenic nitrogen in aquatic systems as a useful method for studying nitrogen cycle. In this study to evaluate the precision and accuracy of Kjeldahl processes, two reference materials (IAEA-NO-3, N-1) were analyzed repeatedly. Measured the ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values of IAEA-NO-3 and IAEA-N-1 were $4.7{\pm}0.2$‰ and $0.4{\pm}0.3$‰, respectively, which are within recommended values of analytical uncertainties. Also, we investigated spatial patterns of ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ in effluent plumes from a waste water treatment plant in Han River, Korea. ${\delta}^{15}N-NO_3$ and ${\delta}^{15}N-NH_4$ values are enriched at downstream areas of water treatment plant suggesting that dissolved nitrogen in effluent plumes should be one of the main N sources in those areas. The current study clarifies the reliability of Kjeldahl analytical method and the usefulness of stable isotopic techniques to trace the contamination source of dissolved nitrogen such as nitrate and ammonia.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.403-411
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• 2007

The purpose of the study was to evaluate fish community, based on conventional at Shannon-Weaver diversity index (H'), and ecological health, based on the Index of Biological Integrity (IBI) using fish assemblage in the eight sites of Nakdong River during June${\sim}$August 1999. Total number of species sampled was 19 species, and two sensitive species of Zacco temminckii (51%) and Rhynchocypris oxycephalus (28%) dominated the fish community. Also, trophic guild analyses showed that insectivore was 87% of the total and omnivore was rare, indicating that the ecological health is well maintained in the system. The pattern of spatial variation in the diversity index(H') was very similar to patterns of the species number and individual number, whereas the pattern of H' was not matched with the tolerance and trophic guild data. The diversity index (H') showed highest (1.56) in Site 6 where the proportion of sensitive species and tolerant species was minimum and maximum, respectively, and where the insectivore and omnivore were minimum and maximum. In other words, the diversity index was not matched at all with the trophic and tolerant guilds, indicating that the conventional index did not reflect the ecological characteristics of fish community in the system. In the mean time, the ecological health (IBI) averaged 33.5 (n=8), indicating "good${\sim}$fair condition" and the IBI values matched with trophic and tolerance guilds. Maximum IBI occurred in Site 2 where the sensitive and msectivore species were nearly maximum, and the tolerant and omnivore species were almost minima, indicating that IBI values were closely associated with the ecological functions and health conditions. Overall data suggest that the conventional diversity index may not effective for a evaluation of fish community, and that in contrast the IBI approach may be a useful tool for diagnosis of stream community.

• Journal for History of Mathematics
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• v.22 no.2
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• pp.27-52
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• 2009

This article discusses the contributions of the leader Oswald Veblen, who was the president of AMS during 1923-1924. In 2006, Korea ranked 12th in SCIE publications in mathematics, more than doubling its publications in less than 10 years, a successful model for a country with relatively short history of modern mathematical research. Now there are 192 four-year universities in Korea. Some 42 of these universities have Ph.D. granting graduate programs in mathematics and/or mathematical education in Korea. Rapid growth is observed over a broad spectrum including a phenomenal performance surge in International Mathematical Olympiad. Western mathematics was first introduced in Korea in the 17th century, but real significant mathematical contributions by Korean mathematicians in modern mathematics were not much known yet to the world. Surprisingly there is no Korean mathematician who could be found in MaC Tutor History Birthplace Map. We are at the time, to have a clear vision and leadership for the 21st century. Even with the above achievement, Korean mathematical community has had obstacles in funding. Many people thinks that mathematical research can be done without funding rather unlike other science subjects, even though they agree fundamental mathematical research is very important. We found that the experience of early American mathematical community can help us to give a vision and role model for Korean mathematical community. When we read the AMS Notice article 'The Vision, Insight, and Influence of Oswald Veblen' by Steve Batterson, it answers many of our questions on the development of American mathematics in early 20th century. We would like to share the story and analyze its meaning for the development of Korean Mathematics of 21st century.

• Journal of Food Hygiene and Safety
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• v.21 no.4
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• pp.250-257
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• 2006

The purpose of this study is to evaluate microbiological contamination of leafy vegetables. Total aerobic bacteria and coliforms were monitored to get the contamination levels and Staphylococcus aureus, Bacillus cereus, Clostridium perfringens, Escherichia coli, Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Listeria monocytogenes, Yersinia enterocolitica, Campylobacter jejuni to detect pathogens with risk of foodpoisoning from fresh vegetables. The colony count of total aerobes and coliforms was also performed to determine the efficacy of washing with tab water by common consumers. 124 samples which are divided into 8 kinds of vegetables - Sesame leaf, Dropwort, Chinese cabbage, Korean leek, Lettuce, Crown daisy, Pimpinella brachycarpa, Chicory were sampled in 2 wholesale markets in Incheon. Mean counts of total aerobic bacteria for individual vegetables ranged from $2.2\times10^6\;CFU/g\;to\;6.0\times10^7\;CFU/g$ and total coliforms were from $4.1\times10^5\;CFU/g\;to\;9.8\times10^6\;CFU/g$. Both show the peaks in summer on this study from March to September. Decrease rates after washing with tab water averaged 81.0% and 82.5% in total aerobic bacteria and coliform counts respectively. Staphylococcus aureus was isolated 8.1%, Bacillus cereus 14.5%, Clostridium perfringens 5.6%, Escherichia coli 18.5%. 11 samples showed overlapped bacterial contamination. For respective vegetables Staphylococcus aureus isolated from 0.0% to 22.2%, Bacillus cereus from 0.0% to 29.4%, Clostridium perfringens from 0.0% to 23.1 %, Escherichia. coli from 0.0% to 35.0%. Escherichia coli O157:H7, Salmonella spp., Vibrio parahaemolyticus, Listeria monocytogenes, Yersinia enterocolitica, Campylobacter jejuni were not isolated. This study is expected to be available as the reference for the basal data of pathogens in fresh vegetables.

• Journal of Food Hygiene and Safety
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• v.21 no.4
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• pp.213-217
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• 2006

The halophilic bacterium Vibrio vulnificus is known to be a foodborne pathogen that causes septicemia in human. V. vulnificus infection is characterized by the high fatality rates and the primary attack against a person who have underlying diseases such as liver cirrhosis. However, there is no effective treatment for V. vulnificus septicemia except for classical treatments such as antibiotics. Recently, it has been known that lipoprotein (LDL) plays a major role in the protection against infection and inflammation. Consequently in this paper we analyzed the effects of LDL on V. vulnificus septicemia. We purified V. vulnificus cytolysin, a major virulent factor of V. vulnificus infection and measured inhibitory effects of mouse serum, cholesterol, and LDL on its hemolytic activity. Next experiments were performed to investigate whether LDL has a protective role against septicemia induced by V. vulnificus in mice. Intraperitoneal injection of LDL (1mg as protein) into mice 3hr before V. vulnificus $(1\times10^6\;CFU)$ injection, and V. vulnificus -induced lethality was determined. For the determination the relationship between LDL or cholesterol and prognosis, we determined serum levels of cholesterol and lipoprotein from V. vulnificus septicemia patients (n=15) who had visited the Chonbuk National University Hospital in Chonju. V. vulnificus cytolysin -induced hemolysis of mice erythrocytes was completely inhibited by serum, cholesterol, and low-density lipoprotein. V. vulnificus- induced lethality of mice injected with LDL showed only 40% compared to 100% of control. In survival groups (n=4) of V. vulnificus septicemia patients (n=15), their serum LDL and cholesterol revealed normal levels ($153.3{\pm}40.7,\;LDL;\;190.8{\pm}16.3$, Total cholesterol). However, in death groups (n=11) showed very low levels ($35.6{\pm}13.9,\;LDL;\;59.2{\pm}15.1$, Total cholesterol). Our study indicates that cholesterol and LDL are a prognosis indicator of V. vulnificus septicemia as well as an inhibitor of virulent action of V. vulnificus cytolysin. We suggested that the serum levels of cholesterol or LDL would be major index in the treatment and prevention of V. vulnificus septicemia.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2004.11a
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• pp.59-70
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• 2004

A randomized double-blind placebo-controlled study was conducted on 63 subjects to determine the antihypertensive effect of a vegetable drink in which sardine protein hydrolysates containing a dipeptide, Valyl-Tyrosine (VY), were incorporated. The subjects, consisting of people with mild hypertension, high-normal blood pressure and normal blood pressure, were randomly divided into test (male/female=25.6, average age 50.1${\pm}$10.4 years old) and control groups (26/6, 49.0${\pm}$5.0). Each subjects in the test group was given 195g of the vegetable drink containing 0.5g of sardine peptides (sardine protein hydrolysates) with 0.4 mg of VY (test drink) once a day for 13 weeks in a row, and subjects in the control group were given the same amount of the vegetable drink without sardine peptides (control drink) in the same manner. In the test group, 40 subjects with mild hypertension of high-normal blood pressure (130 mmHg${\leq}$systolic blood pressure (SBP)<160 mmHg and/or 80 mmHg${\leq}$diastolic blood the start of the test to 134.4${\pm}$11.1 mmHg during the first week of the test period, after which similar values were seen throughout the test period (13 weeks). Compared to the control group, the difference in SBP from vaseline was statistically significant in the test group throughout the intake period. DBP also decreased significantly from 88.0${\pm}$7.9 mmHg at baseline to 83.5${\pm}$8.6 mmHg after 13 weeks. In the control group, SBP and DBP were 140.8${\pm}$8.4 mmHg and 90.5${\pm}$6.6 mmHg respectively at the start of the test, and neither decreased during the test period. In subjects with normal blood pressure, neither those in the test group nor those in the control group showed a significant change in SBP and DBP during the test period. An excessive ingestion test was performed on 25 subjects with hypertension, mild hypertension, high-normal blood pressure, and normal blood pressure by giving 585g (3 times the recommended amount of intake) of the test drink for 14 days in a row. As a result, a significant decrease of blood pressure was observed in the hypertension, mild hypertension and high-normal blood pressure groups, but no excessive decline in blood pressure or any side-effects were associated with any subjects during the test period. In the groups with normal blood pressure, the excessive ingestion of the test drink did not affect blood pressure. In these two studies, physical check-ups and biochemical analyses of blood and urine were also conducted in all subjects, and no abnormalities were observed. These results suggest that the test drink containing sardine protein hydrolysates exhibited the antihypertensive effect in only the subjects with mild hypertension or high-normal blood pressure. No adverse effects were observed in either hypertensive of normotensive subjects.

• Journal of Food Hygiene and Safety
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• v.27 no.4
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• pp.420-426
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• 2012

The purpose of this study was to identify control points through microbiological hazard analysis in the manufacturing processes of starch noodles. Samples were collected from the ingredients, manufacturing processes, equipment and environment. Microbiological hazard assessments were performed using aerobic plate counts (APC), Enterobacteriaceae (EB), E. coli and five pathogens including B. cereus, E. coli O157:H7, L. monocytogenes, Salmonella spp., and S. aureus. The APC levels in raw materials were from 2.12 to 3.83 log CFU/g. The contamination levels after kneading were 4.31 log CFU/g for APCs and 2.88 log CFU/g for EB counts. APCs decreased to 1.63 log CFU/g and EB were not detected after gelatinization, but their levels slightly increased upon cooling, cutting, ripening, freezing, thawing, and separating. The reuse of cooling and coating water would be a critical source of microbial increase after cooling. After drying, APCs and EB counts decreased to 5.05 log CFU/g and 2.74 log CFU/g, respectively, and the levels were maintained to final products. These results suggest that the cooling process is a critical control point for microbiological safety, and the cooling water should be treated and controlled to prevent cross contamination by pre-requisite program.