• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.71-79
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• 1999

As part of an on-going project investigating flux of materials in the Keum River Estuary, we have monitored seasonal variations of nutrients, suspended particulate matter (SPM), chlorophyll, and salinity since 1997. Meteorological data and freshwater discharge from the Keum River Dike were also used, Our goal was to answers for (1) what is the main factor for the seasonal fluctuation of nutrients in the Keum River Estuary? and (2) are there any differences in nutrient distributions before and after the Keum River Dike construction? Nitrate concentrations in the Keum River water were kept constant through the year. Whereas other nutrients varied with evident seasonality: high phosphate and ammonium concentrations during the dry season and enhanced silicate contents during the rainy season. SPM was found similar trend with silicate. During the rainy season, the freshwater discharged from the Keum River Dike seemed to dilute the phosphate and ammonium, but to elevate SPM concentration in the Keum Estuary. In addition, the corresponding variations of SPM contents in the estuarine water affected the seasonal fluctuations of nutrients in the Estuary. The most important source of the nutrients in the estuarine water is the fluvial water. Therefore, the distribution patterns of nutrients in the Estuary are conservative against salinity. Nitrate, nitrite and silicate are conservative through the year. The distribution of phosphate and ammonium on the other hand, display two distinct seasonal patterns: conservative behavior during the dry season and some additive processes during the rainy days. Mass destruction of freshwater phytoplankton in the riverine water is believed to be a major additive source of phosphate in the upper Estuary. Desorption processes of phosphate and ammonium from SPM and organic matter probably contribute extra source of addition. Benthic flux of phosphate and ammonium from the sediment into overlying estuarine water can not be excluded as another source. After the Keum River Dike construction, the concentrations of SPM decreased markedly and their role in controlling of nutrient concentrations in the Estuary has probably diminished. We found low salinity (5~15 psu) within 1 km away from the Dike during the dry season. Therefore we conclude that the only limited area of inner estuary function as a real estuary and the rest part rather be like a bay during the dry season. However, during the rainy season, the entire estuary as the mixing place of freshwater and seawater. Compared to the environmental conditions of the Estuary before the Dike construction, tidal current velocity and turbidity are decreased, but nutrient concentrations and chance of massive algal bloom such as red tide outbreak markedly increased.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.513-523
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• 2017

We evaluated the viability of phytoplankton along the salinity gradient in the flood and ebb tides of spring tide of February and the ebb tide of neap tide of March 2017 in the Seomjin River Estuary. Additional laboratory experiments were also conducted to determine the reason of the pH changes along the salinity gradient using the field natural sample in February. In field, saltwater was well mixed at downstream vertically and the salinity gradient was horizontally appeared toward upstream of freshwater zone. There were strong negative correlations between salinity and nutrient (nitrate + nitrite R=0.99, p<0.001, and silicate R=0.98, p<0.001), implying that those two nutrients of freshwater origin were gradually diluted with mixing the saltwater. On the other hands, relatively high phosphate concentration was kept in the stations of saltwater over 15 psu, indicating that it was caused by resuspended sediments of Gwangyang Bay and downstream by tidal water mixing.Among phytoplankton community structure in winter, Eucampia zodiacus have occupied to be c.a. 70 % in the most stations. Based on the field survey results for survivability of phytoplankton by phytoPAM instrument, there was positive correlations between salinity and chlorophyll a (R=0.82, p<0.001) and, salinity and active chlorophyll a (R=0.80, p<0.001), implying that the dominant marine diatom species may have significantly damaged in low salinity conditions of upstream. Also, maximum mortality rate of phytoplankton caused by low salinity shock was appered to be 75% in the upstream station. In particular, the pH in spring tides of February had tended to increase with high phytoplankton accmulated stations, suggesting that it was related with absorption of $CO_2$ by the photosynthesis of dominant diatom. In laboratory experiments, phytoplankton mass-mortality caused by low salinity shock was also occurred, which is confirmed with reducing the photosynthetic electron transport activity. Following the phytoplankton mass-mortality, bacteria abundance was significantly increased in 24 hours. As a result, the mass-proliferating bacteria can produce the $CO_2$ in the process of biodegradation of diatoms, which can lead to pH decrease. Therefore, marine phytoplankton species was greatly damaged in freshwater mixing area, depending on along the salinity gradient that was considered to be an important role in elevating and reducing of pH in Seomjin River Estuary.

• Childhood Kidney Diseases
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• v.11 no.1
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• pp.24-31
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• 2007

Purpose : Nitric oxide(NO) is a very potent vasodilator synthesized from L-arginine by endothelial cells. We investigated whether urinary NO excretion was altered in various renal diseases in children and whether urinary NO excretion could be used in predicting pathologic causes and fibrosis in renal diseases in children. Methods : We recruited 48 patients(32 minimal change nephrotic syndrome[MCNS] and 16 vesicoureteral reflux[VUR] patients from the pediatric renal clinic in Korea University Guro Hospital. We measured the concentration of nitrite$(NO_2)$ and nitrate$(NO_3)$ by Griess reaction and that of creatinine(Cr) by Jaffe method in randomized spot urines. We then analyzed the urinary$(NO_2+NO_3)/Cr$ ratios and compared the values between each patient group. Urinary $(NO_2+NO_3)/Cr$ ratios were also evaluated according to the recurrence and the degree of proteinuria at sampling in the MCNS group and compared according to the presence of renal scarring and the grade of reflux in the VUR group. Results : The ratios of urinary$(NO_2+NO_3)/Cr$ were significantly increased in the VUR and MCNS groups, as compared to the control group. In the MCNS group, a higher level of urine $(NO_2+NO_3)/Cr$ was observed In frequent relapse patients(relapse over four times within one year after first diagnosis) and the patients with severe proteinuria at sampling, respectively. The VUR group with renal scars also showed a higher level of urinary$(NO_2+NO_3)/Cr$ compared to that without scars. Conclusions : In summary, VUR may play a role in the pathogenesis of VUR and MCNS. NO also seems to affect proteinuria and renal scar formation. (J Korean Soc Pediatr Nephrol 2007;11:24-31)

• Journal of Preventive Medicine and Public Health
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• v.32 no.2
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• pp.170-176
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• 1999

Objectives: To evaluate the protective effects of glutathione (GSH) on the cytotoxicity of mercurial compounds$(CM_3HgCl,\;HgCl_2)$ or cadmium chloride$(CdCl_2)$ in EMT-6 cells. Methods: The compounds investigated were $CH_3HgCl,\;HgCl_2,\;CdCl_2$, GSH, buthionine Sulfoximine(BSO), L-2-oxothiazolidine-4-carboxylic acid(OTC). Cytotoxicity analysis consist of nitric oxide(NO) production, ATP production and cell viability. Results: Mercurial compounds and cadmium chloride significantly decreased cell viability and the synthesis of NO and cellular ATP in EMT-6 cells. GSH was not toxic at concentrations of 0-1.6 mM. In the presence of GSH, mercurial compounds and cadmium did not decrease the production of ATP and nitrite in EMT-6 cells. The protective effects of GSH against the cytotoxicity of mercurial compounds and cadmium depended on the concentration of added GSH to the culture medium for EMT-6 cells. We evaluated the effects of intracellular GSH level on mercury- or cadmium-induced cytotoxicity by the pretreatment experiments. Pretreatment of GSH was not changed ${NO_2}^-$ and ATP production, and pretreatment of BSO was decreased in dose and time-dependent manner. Pretreatment of OTC was increased ${NO_2}^-$ and ATP production in dose- and tine-dependent manner. Because intracellular GSH level was increased by OTC pretreatment, the protective effect on mercury- and cadmium-induced cytotoxicity was increased. Conclusions: These results indicated that sulfhydryl compounds had the protective effects against mercury-induced cytotoxicity by the intracellular GSH levels.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.9
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• pp.1035-1043
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• 2007

A leachate containing an elevated concentration of organic and inorganic compounds has the potential to contaminate adjacent soils and groundwater as well as downgradient areas of the watershed. Moreover high-strength ammonium concentrations in leachate can be toxic to aquatic ecological systems as well as consuming dissolved oxygen, due to ammonium oxidation, and thereby causing eutrophication of the watershed. In response to these concerns landfill stabilization and leachate treatment are required to reduce contaminant loading sand minimize effects on the environment. Compared with other treatment technologies, leachate recirculation technology is most effective for the pre-treatment of leachate and the acceleration of waste stabilization processes in a landfill. However, leachate recirculation that accelerates the decomposition of readily degradable organic matter might also be generating high-strength ammonium in the leachate. Since most landfill leachate having high concentrations of nitrogen also contain insufficient quantities of the organic carbon required for complete denitrification, we combined a shortcut biological nitrogen removal (SBNR) technology in order to solve the problem associated with the inability to denitrify the oxidized ammonium due to the lack of carbon sources. The accumulation of nitrite was successfully achieved at a 0.8 ratio of $NO_2^{-}-N/NO_x-N$ in an on-site reactor of the sequencing batch reactor (SBR) type that had operated for six hours in an aeration phase. The $NO_x$-N ratio in leachate produced following SBR treatment was reduced in the landfill and the denitrification mechanism is implied sulfur-based autotrophic denitrification and/or heterotrophic denitrification. The combined leachate recirculation with SBNR proved an effective technology for landfill stabilization and nitrogen removal in leachate.

• Food Science of Animal Resources
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• v.30 no.3
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• pp.435-442
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• 2010

The study analyzed the effects of salt concentration [high salt (HS) and low salt (LS)] and sodium nitrite ($NaNO_2$), which are typically utilized in Korean processing facilities, on fatty acid composition, free amino acids, microbial counts and sensory characteristics of processed dry-cured ham. Four different treatments were considered: three hams (11.30 kg) salted with 92 g/kg salt (w/w) (HS), three hams (10.65 kg) treated with HS and 100 ppm $NaNO_2$ (HS+$NaNO_2$), three hams (11.42 kg) salted with 62 g/kg salt (w/w) (LS), and three hams (10.62 kg) treated with LS and 100 ppm $NaNO_2$ (LS+$NaNO_2$). Fatty acid composition analysis revealed significantly (p<0.05) higher saturated fatty acid and lower (p<0.05) unsaturated fatty acid in the HS+$NaNO_2$ group compared with the other groups. Glutamate, alanine and lysine free amino acids were higher than the other free amino acids. The processing conditions did not significantly affect the free amino acids of biceps femoris muscles, except for the proline content (p>0.05). In sensory evaluation, the fermentation aroma of the LS group was higher than that of the HS group. The aerobic counts consistently ranged from from $2.3{\times}10^2$ to $1.11{\times}10^4$ CFU/g. Escherichia coli including strain O157:H7, Staphylococcus aureus, and Salmonella spp. were not detected.

• Korean Journal of Food Science and Technology
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• v.33 no.5
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• pp.507-513
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• 2001

An effective extraction methods of a garlic were investigated in order to improve the functional properties of the extracts. The solid yield, electron donating ability (EDA), nitrite-scavenging effects (NSE), peroxide value (POV) and total thiosulfinates contents of garlic extracts were determined. In order to improve the functional properties of extracts prepared with several organic solvents and acids, concentration and pH adjustment of the selected solvent and addition of acids and salts to solvents were also examined. Among the solvents tested, the methanol and ethanol extracts were found to be the most effective on the base of functionality and solid yields. The highest EDA, NSE and thiosulfinate value were obtained with 50% ethanol. The pH control of solvent and addition of citric acid, NaCl and phosphates to 50% ethanol did not affect on the functionality of the extracts. Therefore the optimal solvent for the best functional properties of garlic extract was 50% ethanol.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.7
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• pp.980-988
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• 2014

Seungmagalgeuntang (SG) is broadly used in traditional Oriental medicine especially in Korea, China, and Japan, for its many pharmacological effects. This study was carried out to investigate the antioxidative, antimicrobial, and anticytotoxic activities of SG and fermented seungmagalgeuntang (FSG). DPPH radical scavenging activities of SG and FSG were 70% and 74%, respectively, which increased slightly by fermentation. Nitrite scavenging activities were strongly altered at pH 1.2, (36.4% in SG and 38.3% in FSG) by addition of $200{\mu}g/g$. Superoxide dismutase-like activities were from 21.5% to 23.3% at a concentration of 0.4 mg/mL, and the highest value were observed in FSG. Total flavonoid contents of SG and FSG were 47.1 and $52.1{\mu}g/L$, respectively which shows an increase upon fermentation. In the antimicrobial activity test, $MIC_{50}$ values of SG and FSG were $800{\mu}g/mL$ for Candida albicans and 3,200 and $1,600{\mu}g/mL$ for Staphylococcus epidermidis and Staphylococcus aureus, respectively. Antibacterial effects were higher in FSG compared to SG. Anticytotoxic cadmium toxicities ranged from 63.5% to 76.1% at $10{\mu}g/mL$ of SG and FSG, and the highest value was observed in FSG. In the sensory evaluation, color, flavor, and overall preference values were higher in FSG.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.6
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• pp.684-690
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• 2008

To investigate the applicability of hot water extract (PLW) and ethanol extract (PLE) from Phellinus linteus as functional food and cosmeceutical materials, its total flavonoids content, total phenolics content, electron donating ability (EDA), nitrite-scavenging ability (NSA), SOD-like activity, inhibitory effect of tyrosinase and elastase were examined. Total flavonoids contents of PLW and PLE were 17.31 mg/g and 42.61 mg/g, respectively, and total phenolics contents were estimated as 149.92 mg/g for PLW and 432.42 mg/g for PLE. The EDA of PLW and PLE were $6.49{\sim}92.98%$ and $22.61{\sim}94.28%$. The EDA and total phenolics contents had a high correlation of 0.83. The NSA was pH dependent, and was highest at pH 1.2 and lowest at pH 6.0. The NSA of PLE was higher than that of PLW. The SOD-like activities of PLW and PLE were $14.36{\sim}35.21%$ and $17.27{\sim}81.84%$, respectively, and the activity was dependent on the sample concentration. The tyrosinase inhibitory activity was the highest in PLE ($10.51{\sim}80.93%$) while that of PLW was $4.77{\sim}43.69%$. Finally, the elastase inhibitory activity was $10.01{\sim}76.02%$ at PLE. Based on the above results, we deemed that the ethanol extract of Phellinus linteus was the most pertinent for use as functional food and cosmeceutical materials.

• Korean Journal of Plant Resources
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• v.22 no.5
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• pp.403-411
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• 2009

This study was conducted to gather the basic data on the increase of utilization for the Japanese staunton vine (Stauntonia hexaphylla), native plants which were grown in the southern districts in Korea. We have also determined their partial physical and chemical compositions and their physiological activities. Vitamin C contents in fruit skin was 85.23 mg/100 g, and that in flesh was 61.67 mg/100 g. Total amino acids contents in fruit skin increased much more by 762.72 mg/100 g DW compared to that in flesh by 434.05 mg/100 g DW. Inorganic matter contents were more increased in the fruit skin (108.48 mg/$\ell$) and its main components were K (76.53 mg/$\ell$), Ca (20.20 mg/$\ell$) and Mg (6.22 mg/$\ell$). Total phenol compound and flavonoid contents in 1,000 mg/$\ell$ methanol extracts were 7.3-9.6 mg/$\ell$ and 5.1-6.7 mg/$\ell$. Nitrite radical scavenging activity in 4,000 mg/$\ell$ methanol extracts of fruit skin and flesh for Stauntonia hexaphylla were 79.5% and 77.8%, however, that in seeds was 17.1%. Overall mushroom tyrosinase inhibition activity (% of control) was less than 10.8%. Anti-microbial activities of methanol extracts from the fruit skin against the gram negative and positive microbial strains were not significant in the lower concentration of extracting solution, however, that from flesh and seeds in terms of the inhibition diameter were $8.91{\sim}12.25\;mm$.