• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.302-312
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• 2017

Objectives: In this study, an evaluation of the working environment of furnace workers was performed and the work-relatedness of the occupational diseases were examined Methods: In this study, two electric furnaces at a single casting business site producing manganese-based iron alloy were selected, and occupational exposures to hazardous substances were evaluated for furnace workers and furnace worker assistants. Results: As a result, total dust concentration were $0.407{\sim}3.001mg/m^3$ and respirable dust concentration were $0.196{\sim}0.584mg/m^3$. The highest concentration of crystalline silica was $0.079mg/m^3$ In the case of Masato and Sosuckwhoi crystalline silica, they contained 90.85% and 4.17% respectively. Manganese concentration was the highest at a $0.205mg/m^3$ maximum. The average of black carbon is $11.56{\mu}g/m^3$ and the maximum concentration is $604.23{\mu}g/m^3$. PAHs concentration was the highest at a $78.301{\mu}g/m^3$ of naphthalene. The concentration of carbon monoxide was 18.82 ppm(total average 3.89 ppm) during pouring, and the maximum is 131 ppm. The formaldehyde concentration was 0.003 to 0.007 ppm. Conclusions: It seems that conditions in the past were worse, since casting has recently been performed only twice per day for about 20 minutes, reducing the amount of pouring, and local exhaust systems have been installed one-by-one. In addition, it was judged that the past exposure levels were higher considering the points measured on the back-side due to the risk of damage to the individual samples. It was found that operators could be exposed to high concentrations of crystalline silica, and that they were also exposed to high concentrations of metal(fume) and carbon monoxide during pouring. Therefore, there is a risk that occupational diseases such as lung cancer and COPD may occur with long-term work in such a process.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.450-455
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• 2012

The paper includes the utlization of an activated carbon as a potential adsorbent to remove a hazardous fluorescein dye from an aqueous solution. Batch adsorption experiments were carried out for the removal of fluorescein dyes using a granular activated carbon as an adsorbent. The effects of various parameters such as pH, amount of adsorbent, contact time, initial concentration and temperature of the adsoprtion system were investigated. The experimental results revealed that activated carbon exhibit high efficiencies to remove fluorescein dyes from the aqueous solution. The equilibrium process can be well described by Freundlich isotherm in the temperature range from 298 K to 318 K. From adsorption kinetic experiments, the adsorption process followed a pseudo second order kinetic model, and the adsorption rate constant ($k_2$) decreased with increasing the initial concentration of fluorescein. The free energy of adsorption ${\Delta}G^0$), enthalpy ${\Delta}H^0$), and entropy (${\Delta}S^0$) change were calculated to predict the nature adsorption. The estimated values for ${\Delta}G^0$ were -17.11~-20.50 kJ/mol over an activated carbon at 250 mg/L, indicated toward a spontaneous process. The positve value for ${\Delta}H^0$, 33.2 kJ/mol, indicates that the adsorption of fluorescein dyes on an activated carbon is an endothermic process.

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.159-164
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• 2009

Monomers of oxetane high explosives were theoretically examined in terms of reactivity, reaction mechanism and process of polymerization substituted by azido $(-CH_2N_3)$, nitrato $(-CH_2ONO_2)$ and hydrazino $(-CH_2N_2H_3)$ which belong to the 5th class hazardous materials and have explosiveness under acid catalyst using MINDO/3, MNDO, and AMI methods for formal charge, heat of formation, and energy level. Nucleophilicity and base of oxetane high explosives could be explained by negative charge size of oxetane oxygen atom and reactivity of oxetane in the growth stage of polymerization under acid catalyzer could be expected to be governed by positive charge size of axial carbon atom and low LUMO energy of electrophile. It could be estimated that carbenium ion was more beneficial in the conversion process of oxetane high explosives than that of stabilization energy (13.90~31.02 kcal/mole) of oxonium ion. In addition, concentration of oxonium ion and carbenium ion in equilibrium state influenced mechanism and it was also estimated that $S_N1$ mechanism reacts faster than that of $S_N2$ in prepolymer growth stage considering quick equilibrium based on form and calculation of polymerization under acid catalyzer.

• Analytical Science and Technology
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• v.15 no.3
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• pp.196-213
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• 2002

The alkylphenols, chlorophenols and bisphenol A were determined by gas chromatography/mass spectrometry-selected ion monitoring mode followed by three work-up methods for comparison; EPA method, isoBOC derivatization method and TBDMS derivatization method. Eleven phenols in water samples were extracted with dichloromethane. Also, solid-phase extraction (SPE) with XAD-4 and subsequent conversion to isobutoxycarbonyl derivatives or tert.-butyldimethylsilyl derivatives for sensitive analysis with the selected ion-monitoring (SIM) mode. The recoveries were 85.1~109.9% (EPA method) and 90.3~126.6% (isoBOC derivatization and TBDMS derivatization), respectively. The method detection limit of bisphenol A for SIM were 0.732 ${\mu}g/{\ell}$ (EPA method), 0.002 ${\mu}g/{\ell}$ (isoBOC derivatization) and 0.021 ${\mu}g/{\ell}$ (TBDMS derivatization). The SIM responses were linear with the correlation coefficient varying 0.9755~0.9981 (isoBOC derivatization), and 0.9908~0.9996 (TBDMS derivatization). When these methods were applied to treated wastewater sample from a polyethylene plant, the concentrations of 11 phenols were below the method detection limit.

• Environmental and Resource Economics Review
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• v.17 no.1
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• pp.165-196
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• 2008

This paper reports a quantitative meta analysis of the economic impacts of localized noxious and contaminated sites. Using either hedonic property value or stated preference methods, economists have studied the effects of contamination or noxious activities, or the benefits realized from their elimination, on real estate prices at more than 40 sites. In support of wise public and private investments in environmental quality, most of these studies aim to inform decision makers about the benefits of remediation and cleanup. Their results vary considerably, but there has been no previous systematic effort to analyze the differences and identify shared insights. This study uses established methods of meta analysis to identify points of agreement and differences in this body of literature. The studies are characterized by the type of site, modeling approach, geographic extent of impacts, data features, and other key factors that underlie their value estimates. The impact estimates are normalized as proportional effects on property values. This study attempts to discover whether the estimated economic impacts of contamination or noxious activity differ according to these characteristics of the studies, and whether anything general can be said about the economic consequences of site contamination and remediation. Bivariate, multivariate, and logit techniques are applied to the data. The results suggest that the property value is the most sensitive to water base contamination, published case studies result in systematically greater environmental value than those in unpublished reports, and real estate markets show responses to environmental condition changes.

• Korean Journal of Environmental Agriculture
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• v.19 no.1
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• pp.20-25
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• 2000

Leather processing sludge were amended in sandy loam soil successively to investigate effects on soil properties and radish crop. Total nitrogen concentration of the sludge was $60\;g\;kg^{-1}$, and chromium was $9,048\;mg\;kg^{-1}$. Sludges were treated twice each year for 4 year, and the soils were mixed with sludge to give mixtures equivalent to sludge application rates of 12.5, 25 and $50\;Mg\;ha^{-1}\;yr^{-1}$ in dry matter. Chemical fertilizers $(N-P-K\;:\;280-59-154\;kg\;ha^{-1})$ used as a control. All treated soils were croped to altari and kimjang radish in spring and fall respectively. Organic matter and Cr content in soils were increased with input rate and years of successive application of leather processing sludge, while phosphorous and potassium contents were decreased. Yields of the first harvested altari grown in sludge treated pots were less than control. In the other hand, yields of the first kimjang radish were more than control in proportion with sludge input rates until third year fall. But in fourth year, all sludge treated pot was much less than control in radish yield. Chromium contents of radish in treated soil increased and Cr contents in leaves of radish were higher than roots. Leather processing sludge was considered a potential hazardous resource to soil and crops when it use continuously, because it has high Cr concentration.

• Korean Journal of Environmental Agriculture
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• v.31 no.2
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• pp.170-174
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• 2012

BACKGROUND: Inappropriate discharge of wastewaters and industrial effluents are becoming detrimental to the aquatic environment. The presence of toxic substances on wastewaters can be detected by physicochemical and biological methods. However, physicochemical methods do not give any information about biological toxicity. Therefore, in this study we tried to detect the presence of toxic substance on waters using sulfur-oxidizing bacteria (SOB) as a bioassay. MATERIALS AND RESULTS: The SOB biosensor was first stabilized using synthetic stream water and operated in both continuous and semi-continuous mode. When the SOB biosensor was operated in continuous mode, the effluent electrical conductivity (EC) stabilized at~1.72 dS/m. While in the case of semi-continuous, the EC stabilized at~0.6 dS/m. The SOB system was also operated at different reaction times to ascertain the shortest reaction time for monitoring the toxicity. Finally, the SOB biosensor was fed with nitrite as toxic substance. When 5 mg/L of nitrite was added to the SOB system, the EC decreased immediately. However, the EC recovered after few cycle. CONCLUSION: This study shows that the SOB biosensor can be used as warning system to protect aquatic environment from hazardous materials. Although SOB biosensor can not give specific information about the toxic substances, it can assess whether the water is toxic or not.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.183-192
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• 2016

Silver nanomaterials have been intensively applied in consumer products of diverse industrial sectors because of their strong biocidal properties and reported to be hazardous to aquatic organisms once released in the environment. Nanomaterials including sliver, are known to be different in toxicity according to their physicochemical characteristics such as size, shape, length etc. However studies comparing toxicity among silver nanomaterials with different physicochemical characteristics are very limited. Here, toxicities of silver nanomaterials with different size (50, 100, 150 nm), length (10, $20{\mu}m$), shape (wire, sphere), and coating material (polyvinylpyrrolidone, citrate) using OECD test guidelines were evaluated in aquatic species (zebrafish, daphnia, algae) and compared. On a size property, the smaller of silver nanomaterials, the more toxic to tested organisms. Sphered type of silver nanomaterials was less toxic to organisms than wired type, and shorter nanowires were less toxic than longer ones. Meanwhile the toxic effects of materials coated on silver nanomaterials were slightly different in each tested species, but not statistically significant. To the best of our knowledge, it is first investigation to evaluate and compare ecotoxicity of silver nanomaterials having different physicochemical characteristics using same test species and test guidelines. This study can provide valuable information for human and environmental risk assessment of silver nanomaterials and guide material manufacturers to synthesize silver nanomaterials more safely to human and environment.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.65-72
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• 2010

We used fluorescence detector to analyse total aflatoxins (G1, G2, B1, B2) with TFA (Trifluoroacetic acid) derivation method and PHRED (Photochemical reactor enhanced detection) method. PHRED method was superior in reproduction and convenience, but TFA derivation method was superior in selectivity and sensitivity. The recovery rate of aflatoxin B1, B2, G1 were more than 80%, and G2 was more than 70%. The detection limit of B1, B2, G1 and G2 were respectively 0.05, 0.05, 0.2 and $0.1\;{\mu}g/kg$. Confirmed method was used to analyse total aflatoxins in total 316 items as 9 kinds 137 dried fruits and 10 kinds 179 spices. By the result, Aflatoxins were detected in 27 dried fruits (19.7%) and in 87 spices (48.6%).

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.88-94
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• 2013

The hexavalent chromium (Cr(VI)) is well known as a hazardous ion, presumably inducing dermatic diseases and if serious cancer. The present study concerns the binding capacity of Cr(VI) ions in the cement powder and matrix for a quantitative technique of Cr(VI) ions in cement to influence human health. Both the water-soluble and acid-soluble Cr(VI) ions present in 3 types of ordinary Portland cement (OPC), pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS), and silica fume (SF) were measured using the spectrophotometer. As a result, it was found that the concentration of water-soluble Cr(VI) ion in cement ranged from 10.5 to 18.9mg/kg-cement, and in the additional materials a very low value of Cr(VI) ion was measured. Acid-soluble Cr(VI) ion was even higher than water-soluble Cr(VI) ion, ranging from 172.4 to 318.2mg/kg-cement. Nevertheless, the concentration of acid-soluble Cr(VI) ion is not proportional to addition of acid. It depends rather the variable pH of solvent involving cement paste. As enough cement hydration occurs, the binding capacity of Cr(VI) ion increases, inhibiting this ions from leaching out in the presence of hydration products such as ettringite or tri-calcium aluminate which bind Cr(VI) ion by ion-exchange.