• Journal of Dairy Science and Biotechnology
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• 제39권3호
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• pp.104-112
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• 2021

This study was conducted to evaluate the efficacy of commercial disinfectants at inactivating Enterobacter sakazakii (Cronobacter spp.) in water. Disinfectant I contained 6.15% sodium hypochlorite, and disinfectant II contained both 2.25% n-alkyl dimethylbenzyl ammonium chloride and 2.25% n-alkyl ethylbenzyl ammonium chloride. Disinfectant I was added to distilled water to obtain a range of residual chloride concentrations at 50 ppm intervals with a maximum of 1-1,000 ppm. Disinfectant II was prepared at concentrations ranging from 1-200 ppm with 5 ppm intervals. Exposure time for all solutions was 10 min. In total, 58 E. sakazakii (Cronobacter spp.) strains were tested in this study. Nine isolates were obtained from clinical samples, and 49 isolates were obtained from environmental samples. Seven strains (6 clinical and 1 environmental) were able to survive in 100 ppm disinfectant I, and a maximum of 5 ppm of disinfectant II. Fifty one strains (3 clinical and 48 environmental) were not killed in 10 ppm of disinfectant I and 1 ppm of disinfectant II in water. In conclusion, this study demonstrated that clinical E. sakazakii (Cronobacter spp.) strains displayed 5- to 10-fold higher resistance to disinfectants than environmental E. sakazakii (Cronobacter spp.) strains. Disinfectant II, containing quaternary ammonium compounds, was shown to be more potent in inactivating E. sakazakii (Cronobacter spp.) in water used to clean infant formula manufacturing equipment than disinfectant I.

• Environmental Engineering Research
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• 제13권1호
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• pp.33-40
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• 2008

Levels of arsenic in stream and reservoir waters affected by an abandoned gold mine were examined. The abandoned mine has been left without proper civil and remedial works preventing potential environmental hazards. Field and laboratory chemical analyses revealed that the stream waters downgradient from the mine area were severely contaminated with arsenic and furthermore the reservoir water, 2-3 km away from the mine, also contained substantial levels of As, far exceeding the Korean stream water standard. Relatively higher pH values (6.5-9.4) enhanced mobility of As and mainly sustained substantial As concentration in waters. Chemistries of the stream water, groundwater and reservoir water were dominated by two main factors including effects of mine effluent and anthropogenic agricultural activities. Considering that there has been a substantial As input to the reservoir and the reservoir water has been used for agricultural and domestic uses, immediate remedial works are essentially required.

• 한국식품조리과학회지
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• 제16권6호
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• pp.623-628
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• 2000

The antioxidative effect of mugwort extracts was measured by DPPH and LDL with four different solutions (70% acetone, ethanol, hot water, cold water). Mugwort extracts contained 3.2% of polyphenol, 380 RE/l00 g of vitamin A, 16.2 mg/100 g of vitamin C, and 5.1 ${\alpha}$-TE/100 g of vitamin E. DPPH revealed the effect in the order of 70% acetone, hot water, ethanol, and cold water. In particular, 70% acetone showed outstandingly stronger activity than the control group. Also, when 10 ${\mu}\ell$ was added, the effect was well noticed. But the antioxidative activity was hardly seen at 15 ${\mu}\ell$. LDL exhibited the same order of strength in proportion to mugwort＇s concentration. Against the control group, the activity of 70% acetone was 7 times, hot water and ethanol 6 times, and cold water 2 times. This result is attributable to the antioxidative increase of polyphenol and antioxidative vitamins.

• 한국산업융합학회 논문집
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• 제12권3호
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• pp.137-142
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• 2009

Burning velocity of methane-air mixtures with water vapor have been measured to study the process of flame propagation using schlieren photographs and computation. The computations were carried out for the burning velocity using premix code of Chemkin program to compare the experimental results. The quantity of water vapor contained were changed 5% and 10% of total mixtures, and equivalence ratio of mixtures between 0.8 and 1.2 were tested under the ambient temperature 323K and 373K. The results showed little difference between these two methods, the burning velocity was decreased by increasing the water vapor contents due to the interruption of flame development. And, the effect of ambient temperature was less significant by increasing the water contents on the burning velocity.

• 상하수도학회지
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• 제13권3호
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• pp.56-60
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• 1999

In this study the feasibility of usage of raw sludge (sludge from water treatment plant) and chalk from schools and institutes was investigated to remove the phosphorus in water and wastewater. In this study phosphorus removal efficiencies of sludge and chalk were investigated by changing various factors. The time to reach the equilibrium using chalk and raw sludge under different pHs was obtained. Based on this result, Freudlich adsorption isotherm was applied. Results showed that a portion of phosphorus was removed by adsorption to chalk and raw sludge. The phosphorus removal efficiency using calcinated chalk was about three times higher than that of chalk. It means that some portion of $CaCO_3$ contained in chalk was converted to CaO by calcination and this was proved by X-ray diffraction experiment. About 90% phosphorus removal was observed using sludge and calcinated chalk respectively while about 20% phosphorus removal efficiency was achieved using chalk from the water sample in Lake Sihwa.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2547-2555
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• 2023

Amberlite IRN-78 resin was incorporated with iron to make a hybrid resin for the removal of silica from the borated water of nuclear power plants. The hybrid resin contained 0.84 wt % iron compounds upon pyrolysis. In batch experiments carried out at room temperature, 1 g of the hybrid resin removed ~60 ㎍ silica from 1 ppm borated water in ~120 min. The efficiency of the hybrid material increased with the resin quantity, decreased with silica concentration, and remained unchanged at different pH values. Freundlich and Temkin isothermal adsorption dominated the silica removal process and followed the pseudo-first-order and intra-particle diffusion mechanism simultaneously. The concentration of the leached iron remained appreciably under the safe limits of 200 ㎍/l during the experiments. This detailed study suggests the use of hybrid resin for the removal of silica from borated water streams and other similar systems.

• 한국식생활문화학회지
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• 제16권3호
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• pp.235-242
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• 2001

Chemical properties of the different parts of watercress(Oenanthe javanica D.C.) grown and harvested from the culture fields under different cultivating methods were studied. In proximate analyses of watercress in parts, moisture contained more in stem than in root or in leaf, but crude protein and crude lipid contents were lower in stem than in root or in leaf. Crude ash in root contained up to about double amount in leaf or stem. Major mineral elements detected in watercress were Fe, Mg, Ca, and K, and their contents in root was higher than those in stem or leaf. Especially, Fe in root was significantly higher than that in stem or in leaf. Total free sugar composed mainly with fructose and glucose, was the highest in watercress from Hwasoon and followed the watercress from Jeonju and Donggok in order. Free sugar content was highest in leaf and the lowest in root. Major water-soluble vitamins were vitamin C, thiamin and biotin and the content of vitamin C was higher than others. These vitamins contained more in leaf than in stem or root. Niacin contained 6.09 mg/100 g in leaf of watercress from Hwasoon, which was much higher than others, but it was not detected in stem of watercress from Jeonju. Organic acids detected were oxalic acid, citric acid and malic acid and other 12 organic acids were not detected. In fatty acid composition, there were significant differences among watercresses from different parts and different culture fields. Linoleic acid, linolenic acid and palmitic acid were major fatty acids contained in watercress and it took about 80% of the total content. Amino acid content in leaf was higher than that in root and in stem. Glutamic acid and proline were major amino acids in stem of watercress from Jeonju and in stem of watercresses from Hwasoon and Donggok, respectively. In leaves of all three watercresses glutamic acid content was the highest.

• 한국식품저장유통학회지
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• 제8권4호
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• pp.469-474
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• 2001

대나무 줄기 및 잎의 열수추출물의 영양학적 가치를 검토코자 화학성분을 분석하였다. 대나무 줄기와 잎 추출물의 고형분은 줄기가 3.0-3.5%, 잎이 2.6-2.9%로 줄기에서 더 높은 함량을 보였고, 조단백질은 0.56-0.69% 범위로 왕대의 줄기와 잎 추출물에서 모두 0.69%로 가장 높은 함량을 보였으며, 조지방은 0.28-0.58% 범위였는데, 솜대의 밀이 0.58%로 가장 높은 함량을 나타내었다. 무기성분의 함량은 K, P, Mg 순으로 높았으며 K와 P의 함량은 왕대의 줄기 추출물이 각각 658.7, 94.0mg%로 가장 높았는데, 특히 K의 함량은 모든 죽종의 줄기 추출물에 잎 추출물에 비해 현저히 높은 함량을 보였다. Mg은 맹종국줄기 21.2mg%, 솜대줄기 13.5 mg%, 왕대줄기 13.3mg%이고, 맹종죽잎 25.3mg%, 솜댓잎 23.0mg%, 왕댓잎 35.0mg%로 해당 죽종의 줄기 추출물이 잎 추출물에 비해 낮은 함량을 보였다. 추출물의 유리당 함량은 sucrose가 맹종죽줄기에서 1.1%, fructose는 솜대줄기에서 0.51%, glucose는 왕대줄기에서 0.6%의 함량으로 가장높았는데 전체적으로 줄기 추출물이 밀 추출물에 비해 높은 함량을 보였다. 추출물들의 유기산 함량은 malic acid 및 acetic acid가 높게 나타났으며, 왕대 줄기에서 magic acid 44.2m7% 및 acetic acid 54.0mg%로 가장 높은 함량을 보였다. 총아미노산 함량은 줄기 추출물에서는 aspartic acid가 가장 높은 함량을 보였는데, 왕대 42.2mg%, 솜대 39.9mg%, 맹종죽 34.6mg% 순이었다. 잎 추출물에서는 glutamic acid의 함량이 가장 높았으며 맹종죽 19.3mg%, 왕대 18.5mg%, 솜대 15.7mg% 순이었다.

• 한국습지학회지
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• 제9권1호
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• pp.79-89
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• 2007

This paper provides a comprehensive overview of the present status of several environmental problems caused by emerging toxic substances such as persistent organic pollutants (POPs), endocrine disrupting chemicals (EDCs), and arsenic in various environmental media in Vietnam. Monitoring data reported during the 1990s demonstrated elevated contamination of DDTs in most of these compartments in Vietnam. Studies in frame of the Asia-Pacific Mussel Watch Program revealed that fish, mussels and resident birds from Vietnam contained higher concentrations of DDTs as compared to other countries in region, suggesting the role of Vietnamese environment as a significant emission source of DDT in the Southeast Asian region. The estimated dietary intakes of PCBs and DDTs for Vietnamese were relatively high among Asian developing countries, suggesting potential risk for humans posed by thesechemicals. Widespread contamination of some endocrine active compounds such as alkylphenols and phthalates was observed at various sites along the coasts of northern and middle Vietnam. The presence of significant source of bisphenol-A along Red River estuary was revealed with the concentrations comparable to those reported for developed nations. A case study on seasonal variation of alkylphenols and phthalates in surface water of river delta and estuary of north and middle Vietnam indicated the differences in distribution of these compounds between dry and rainy seasons. Higher concentrations of alkylphenols and phthalates were found in dry season in estuary; while the contrasting pattern was observed in the river delta, showing elevated residues in rainy season. This result suggests the different behavior of alkylphenols and phthalates in river delta and coastal environment. From ecotoxicological perspectives, concentrations of bis-phenol A and di(2-ethylhexyl)phthalates [DEHP] in surface water from some locations in Vietnam exceeded the guideline values for Ecotoxicological Effects and the Environmental Risk Limit, respectively, suggesting potential for toxic implications on aquatic wildlife. Widespread and elevated arsenic contamination was discovered inour recent surveys in groundwater in a large area of suburban areas of Hanoi city, the capital of Vietnam. The most recent investigation in 4 villages showed about more than 50 % of groundwater samples contained As concentrations exceeding 50 g/L (the WHO and Vietnamese standard). In particular, in Son Dong villages, 58 % of samples analyzed contained As concentrations higher than 200 g/L. Good correlations were found in As concentrations in water and hair and urine of peoples in corresponding families, suggesting the chronic exposure to As by people living in As-contaminated ground water areas. In Son Dong village, As levels in hair (mean: 1.7 mg/kg dry wt) and urine (g/g creatinine) exceeding the reference values recommended by WHO, suggesting potential for human risk posed by long term accumulation of As in human body. Future studies should be focused on the time trends of POPs and EDCs in biota in Vietnam in order to predict future trend of contamination and to reveal new clues for understanding possible toxic impacts on aquatic organisms. The issues of arsenic contamination in groundwater and their chronic toxic implications on human health should be systematically investigated in the future.

• 한국태양에너지학회 논문집
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• 제31권4호
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• pp.27-33
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• 2011

To find effective way of the production of distilled water for drought and flood with solar radiation, three boxes were made same base each 1000mm ${\times} $1000mm and tops are 45 degree. Individual boxes contained the sea water, rain water and surface water were placed at the same location and same time. Condensation of each box has been compared. On clear day production of distilled water in the box with sea water was 36% and 32% less than boxes with rain water and surface water. The maximum condensation reached when the temperature of the top and bottom parts are equal. As concentration of sea water increased production of distilled water was decreased. In the box with sea water, the surface temperature was lower than 3cm below the surface. Optimum collector area for producing distilled water 2000ml of these three boxes were $3.75m^2$