• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.737-746
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• 2008

Recently, NDTs (Non-Destructive Techniques) using electromagnetic(EM) properties are applied to the performance evaluation for RC (Reinforced Concrete) structures. Since nonmetallic materials which are cement-based system have their unique dielectric constant and conductivity, they can be characterized and changed with different mixture conditions like W/C (water to cement) ratios and unit cement weight. In a room condition, cement mortar is generally dry so that porosity plays a major role in EM properties, which is determined at early-aged stage and also be affected by curing condition. In this paper, EM properties (dielectric constant and conductivity) in cement mortar specimens with 4 different W/C ratios are measured in the wide region of 0.2 GHz~20 GHz. Each specimen has different submerged curing period from 0 to 28 days and then EM measurement is performed after 4 weeks. Furthermore, porosity at the age of 28 days is measured through MIP (Mercury Intrusion Porosimeter) and saturation is also measured through amount of water loss in room condition. In order to evaluate the porosity from the initial curing stage, numerical analysis based on the modeling for the behavior in early-aged concrete is performed and the calculated results of porosity and measured EM properties are analyzed. For the convenient comparison with influencing parameters like W/C ratios and curing period, EM properties from 5 GHz to 15 GHz are averaged as one value. For 4 weeks, the averaged dielectric constant and conductivity in cement mortar are linearly decrease with higher W/C ratios and they increase in proportion to the square root of curing period regardless of W/C ratios.

• Journal of Food Hygiene and Safety
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• v.15 no.4
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• pp.328-333
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• 2000

This study was carried out to changes in chemical and microbiological properties of spring waters in Tongyeoung area. In this paper, ninety spring water samples were collected from 9 station for 11 month to evaluated chemical and bacteriological water quality. Range and mean values of constituents of the samples are as followed; water temperature 5.2~25.8$^{\circ}C$, 16.3$^{\circ}C$, pH 6.0~7.2, 6.7, total residue 33.6~210 mg/1, 90.6 mg/1, turbidity 0.35~5.48, 1.45NTU, KMnO4 consumed 0.51~4.21 mg/1, 1.39 mg/1, chloride ion 6.23~42.5, 16.7 mg/l, phosphate-phosphorus ND-0.04, 0.02 mg/1, nitrite-nitrogen ND~0.02, 0.01 mg/1, nitrate-nitrogen ND~3.56, 1.42 mg/1, ammonia-nitrogen ND~0.20, 0.14 mg/1, dissolved total nitrogen ND~3.78, 1.57 mg/1, iron 0.04~0.28, 0.13ppm, zinc 0.03~0.66, 0.20ppm, mangan ND~0.01, allumium 0.14~0.58, 0.39ppm, copper ND~0.01, 0.01, lead ND~0.01, 0.01ppm, Arsenic ND~0.01, 0.01ppm, mercury ND~0.02, chrome not detected, cadmium not detetced respectively. The viable cell counts of the spring waters ranged 5.0~760/m1(means 130/m1). Range and mean value of total coliform and focal coliform MPN's of the spring waters were 0~2,400MPN/100 ml, 73MPN/100 ml and 0~540MPN/100 ml, 21MPN/100 ml. Spring water quality was usually poor with viable cell counts exceeding 130 CFU/liter and the coliform counts in spring waters of 73 MPN/liter. Composition of coliform by IMViC reaction was 33.3% E. coli, 15.6% Citrobacter freundii, 35.6% Klebsiella aerogenes and others.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.31-39
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• 2002

Pollutants from industry, mining, agriculture, and other sources have contaminated sediments in many surface water bodies. Sediment contamination poses a severe threat to human health and environment because many toxic contaminants that are barely detectable in the water column can accumulate in sediments at much higher levels. The purpose of this study was to make optimal treatment and disposal plan o( sediment for water quality improvement in small-scale resevoir based on an evaluation of degree of contamination. The degree of contamination were investigated for 23 samples of 9 site at different depth of sediment in small-scale J river. Results for analysis of contaminated sediments were observed that copper concentration of 4 samples were higher than the regulation of hazardous waste (3 mg/L) and that of all samples were exceeded soil pollution warning levels for agricultural areas. Lead and mercury concentration of all samples were detected below both regulations. Necessary of sediment dredge was evaluated for organic matter and nutrient through standard levels of Paldang lake and the lower Han river in Korea and Tokyo bay and Yokohama bay in Japan. The degree of contamination for organic matter and nutrient was not serious. Compared standard levels of Japan, America, and Canada for heavy metal, contaminated sediment was concluded as lowest effect level or limit of tolerance level because standard levels of America and Canada was established worst effect of benthic organisms. The optimal treatment method of sediment contained heavy metal was cement-based solidification/stabilization to prevent heavy metal leaching.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.538-544
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• 1985

This study was carried cut to evaluate the water quality of spring waters in Pusan area(see Fig. 1). In this experiment, twenty-five water samples were collected from 5 stations from December 1983 to August 1984. Range and mean values of constituents of the samples are as follows: pH $5.80{\sim}7.25$, 6.60; water temperature $6.0{\sim}23.0^{\circ}C,\;12.9^{\circ}C$; total residue $33.0{\sim}325mg/l$, 121.2mg/l; alkalinity $4.75{\sim}51.6mg/l$, 24.1mg/l; hardness $9.47{\sim}85.0mg/l$, 30.3mg/l; electrical conductivity $0.495{\sim}2.750{\times}^2{mu}{\mho}/cm,\;1.239{\times}10^2{\mu}{\mho}/cm$;turbidity $0.54{\sim}7.80$NTU, 2.04NTU; $KMnO_4$ consumed $0.51{\sim}8.47mg/l$, 1.96mg/l; chloride ion $4.91{\sim}36.0mg/l$, 12.55mg/l; fluoride ion ND-0.30ppm, 0.08ppm; nitrate-nitrogen ND-8.94mg/l, 1.94m:g/l; nitrite-nirogen ND-0.10mg/l, 0.03mg/l; ammonia-nitrogen ND-0.16mg/l, 0.03mg/l: phosphate-phosphorus ND-0.09mg/l, 0.03mg/l; silicate-silicious $0.42{\sim}22.7ng/l$, 7.96mg/l; copper ND-10.5ppb, 2.46ppb; lead ND-22.7ppb, 3.54ppb; zinc ND-103ppb, 21.33ppb; iron $20.3{\sim}2,800ppb$, 801.72ppb, respectively. Arsenic, cyan, cadmium, manganese, mercury, chrome and phenol were not detected. Total residue, electrical conductivity, turbidity and chloride ion of station 1 (Milrakdong) were higher than others as 178.1mg/l, $2.127{\times}10^2{\mu}{\mho}/cm$, 3.16NTU and 16.32mg/l. The concentration of silicious had a great influence on precipitation. The concentration of fluoride ion of spring waters was lower as 0.08ppm than the criterion for drinking water as 1ppm, while iron was exceed 2.7 times as 801.72ppb.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.4
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• pp.476-483
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• 2005

This experiment was planned to develop a functional supplement by food resources to prevent and lessen the deleterious effects caused by environmental pollutants such as polluted food, air, water and heavy metals. The goal of this study was to investigate the effects of peking-duck extracts supplemented with six kinds of medicinal herbs (DJ) on the intoxication of lead and mercury in rats. Sprague-Dawley rat weighing $150g\pm15g$ g, were randomly assigned to 5 groups, basal diet only (NCG), heavy metal without DJ injection (HCG), heavy metals and DJ (3 mg/mL) injection (HMLD), heavy metal and DJ (30 mg/mL) injection (HMMD), heavy metal and D] (300 mg/mL) injection (HMHD). Mecury (Hg) and lead (Pb) injected at the level of 50 ppm for 17 days. Also DJ oral feeding was continued for 31 days. The result of this study were as follows; Food intake and body weight gain in heavy metal administered groups were lower than those of control group (NCG). The activities of GOT, GPT and BUN level were significantly reduced in DJ-treated groups as compared to HCG. DJ was shown to suppress the accumulation of Hg and Pb in serum. The results suggest that DJ might have protective effect on Hg and Pb intoxication.

• Journal of Food Hygiene and Safety
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• v.16 no.4
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• pp.324-332
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• 2001

Foods constitute a large portion of heavy metal exposure toward general population and attract a deep concern with respect to assuring human health. This study summarized published data in Korea on the content, and dietary intake of heavy metals and assessed their risk potential in comparison with foreign data. An analysis for the yearly fluctuation of metal contents including arsenic, cadmium, mercury and lead by flood group (marine fishes, coastal shellfishes, freshwater fishes, cereal grains) exhibited a decreasing trend from the 1970s to the 1990s. When compared with domestic standards of heavy metals, their mean contents were below the limit and their maximum values seldom exceeded the limit. The data on the dietary intake of heavy metals by Koreans showed a decreasing trend from the 1980s to the 1990s. The average intakes offs and Hg were 6∼8% and those of Cd and Pb were 50∼80% of PTWI(provisional tolerable weekly intake), all of which were below the tolerance. As the extreme intakes of these metals may exceed the PTWI, a careful assessment for them may be necessary. Dietary intakes of Cd, Hg and Pb by Koreans lie in the mid-level among countries cited in the GEMS/Food monitoring data. As fishery foods are suspecious of contamination with Hg, Cd and As, and floods in general are with Pb, it is necessary to establish legal limits for these metals and monitor any progress of their contamination. Furthermore, overall assessment of exposure to heavy metals from all sources including floods, air, drinking water and occupation should be made in order to confirm the dietary risk factors and to assure the safety of food resources.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.906-914
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• 2020

To investigate the usefulness of natural plants, physicochemical characteristics, functional components and physiological activities of dodder(Cuscuta australis R.Brown) were experimented. The extraction of dodder was carried out at 60℃ in shaking bath with 10 times of distilled water for three hours. Harmful metals such as lead, cadmium and arsenic were not detected, but the content of mercury from dodder was 0.0004ppm in acceptable standards. The extraction yield was 23.45%, total content of phenolics equivalent to gallic acid was 699.8 mg/100g and total content of flavonoid equivalent to naringin was 373.8 mg/100g. 28 kinds of free amino acids were detected with the contents of 252mg/100g in the dodder extract, and the contents of anserine and sarcosine were analysed highest in all amino acids. From the comparison of physiological activities of dodder extract with those of ascorbic acid, total reducing power, electron donating ability based on DPPH radical scavenging and ferric reducing antioxidant power was equivalent to 88%, 56% and 40%, respectively, of ascorbic acid. The nitrite scavenging activity of dodder extract was 78% of ascorbic acid on pH 1.5, but the antioxidant index of dodder on perilla oil was about 4 times greater than that of ascorbic acid.

• Macromolecular Research
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• v.9 no.5
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• pp.267-276
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• 2001

In order to endow with new bioactive functionality from demineralized bone particle (DBP) as natural source to poly(L-lactide) (PLA) synthetic biodegradable polymer, porous DBP/PLA as natural/synthetic composite scaffolds were prepared and compared by means of the emulsion freeze drying and solvent casting/salt leaching methods for the possibility of the application of tissue engineered bone and cartilage. For the emulsion freeze drying method, it was observed that the pore size decreased in the order of 79$\mu\textrm{m}$ (PLA control) > 47$\mu\textrm{m}$ (20% of DBP) > 23 $\mu\textrm{m}$ (40% of DBP) > 15$\mu\textrm{m}$ (80% of DBP). Porosities as well as specific pore areas decreased with increasing the amount of DBR. It can be explained that DBP acts like emulsifier resulting in stabilizing water droplet in emulsion. For the solvent casting/salt leaching method, a uniform distribution of well interconnected pores from the surface to core region were observed the pore size of 80 ∼70 $\mu\textrm{m}$ independent with DBP amount. Porosities as well as specific pore areas also were almost same. For pore size distribution by the mercury intrusion porosimeter analysis between the two methods, the pore size distribution of the emulsion freeze drying method was broader than that of the solvent casting/salt leaching method due to the mechanism of emulsion formation. Scaffolds of PLA alone, DBP/PLA of 40 and 80%, and DBP powder were implanted on the back of athymic nude mouse to observe the effect of DBP on the induction of cells proliferation by hematoxylin and eosin staining for 8 weeks. It was observed that the effect of DBP/PLA scaffolds on bone induction are stronger than PLA scaffolds, even though the bone induction effect of DBP/PLA scaffold might be lowered than only DBP powder, that is to say, in the order of DBP only > DBP/PLA scaffolds of 40 and 80% DBP > PLA scaffolds only for osteoinduction activity. In conclusion, it seems that DBP plays an important role for bone induction in DBP/PLA scaffolds for the application of tissue engineering area.

• Journal of Food Hygiene and Safety
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• v.25 no.2
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• pp.83-90
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• 2010

This study was conducted to investigate the residue amount of harmful materials on the 153 commercial medical herbs in Gwangju area. It was performed using the GC-ECD, GC-NPD, GC-MSD and the LC-UVD, LC-FLD, LC-MSD to analyze 200 pesticides. The heavy metals were determined using a Mercury analyzer and AAS. The sulfur dioxides were analyzed by modified Monnier-Williams method. The residual pesticides were detected in 7 samples, and were over MRLs (Maximum Risk Levels) in 2 samples (1.3%). The mean values of heavy metal contents (mg/kg) were Pb, 0.570; Cd, 0.081; As, 0.082; Hg, 0.0093. The measured values of Pb, As, Hg showed within MRLs. The excess samples of MRLs were 3 samples (changchul 2, cheongung 1) on Cd. The sulfur dioxides were over MRLs in 7 samples (4.6%), hwanggi and gugija. These results will be used to establish on the regulation of commercial medical herbs in Gwangju area.

• Polymer(Korea)
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• v.30 no.6
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• pp.525-531
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• 2006

In this study, Sulfonated PONF-g-styrene ion exchange fibers were synthesized by radiation induced graft copolymerization. And also, hybride ion exchange fibers, which was combined sulfonated PONF-g-styrene fibers and cationic ion exchange resin, were fabricated by hot melt adhesion method and then their adsorption properties were investigated. ion exchange capacity and water content of hybrid ion exchange fibers increased as compared with those of bead and ion exchange fiber. Their maximum values were 4.76 meq/g and 23.5%, respectively. Adsorption breakthrough time for mercury of hybrid ion exchange fiber was slower than those of bead resin and fibrous ion exchanger. It's value was 130 minutes. Their breakthrough time become short as increasing of pH, and concentration. The initial breakthrough time was observed before and after 10 minutes as increasing of concentration. The adsorption of hybrid ion exchange fibers for $Hg^{2+}\;Pb^{2+},\;Cd^{2+}$ among heavy metals in the mixed solution was observed before 20 min. And also, The adsorption for $Hg^{2+}$ among the heavy metals by hybride ion exchange fibers was observed.