• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.371-380
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• 2022

Objectives: To ensure that employers handling petroleum compounds understand whether petroleum-based UVCB (unknown or variable composition, complex reaction products, or biological materials) substances contain hazardous substances and comply with the Occupational Safety and Health Act, petroleum-based UVCB substances were analyzed and the results from samples were compared with MSDS (Material Safety Data Sheet) contents. Methods: Twenty-one petroleum samples were analyzed using GC-MS (Gas Chromatography-Mass Spectrometry), targeting ten volatile organic compounds regulated by the Occupational Safety and Health Act. Results: The target chemicals were detected in 13 out of 21 samples. All 13 samples were in the naphtha (low boiling point naphthas (gasolines)) group. There were also naphtha group samples containing 2% benzene. Some naphtha samples used as solvents contained about 1% benzene. Conclusions: This study shows that naphtha group petroleum substances contain hazardous chemicals in many cases. In particular, if benzene, n-hexane, and toluene with low occupational exposure limits are contained above the limit concentration. Such information should be delivered in the article on MSDS legal regulations.

• Korean journal of food and cookery science
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• v.16 no.2
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• pp.173-181
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• 2000

To understand the influences of NaCl concentration and fermentation temperature on the ripening process of low salt fermented squids, squid with 5%, 7% and 9% salt were fermented at 10$\^{C}$ and 20$\^{C}$. The result of the changes of volatile basic nitrogen and free amino acids during the fermentation of squids are as follows. As a result of the observations on the changes of physicochemical components during the fermentation process of the low-salted squids, all the pH, VBN and NH$_2$-N were increased and therefore the fermentation was promoted. Considering the changes of net components according to the fermentation, ATP (Adenosine triphosphate) and ADP (Adenosine diphosphate) lost and could not be detected among the nucleotides and their related compounds. Besides, AMP (Adenosine monophosphate) existed only in the initial stage and inosine, hypoxanthine were the main components of nucleotides and their related compounds. Nonvolatile organic acids are mainly lactic acid, acetic acid and also they occupied more than 80%. Seeing the composition of free amino acid, the major amino acids are proline, arginine, methionine, alanine and glutamic acid.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.10
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• pp.1024-1030
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• 2006

Genus Nitrospira and Nitrobacter species are the key nitrite-oxidizing bacteria(NOB) in nitrifying wastewater treatment plants. It has been hypothesized that genus Nitrospira are K-strategists(low $K_6$ value) that can exploit low amounts of nitrite more efficiently than Nitrobacter. In contrast, Nitrobacter species are r-strategists(high $V_{max}$) that can grow faster than Nitrospira. It has also been known that the availability of organic compounds and dissolved oxygen as well as nitrite affects the distribution of NOB. In this study, we determined the distribution and competition of NOB in wastewater nitrification systems where nitrite, organic compounds, and dissolved oxygen concentrations were compositively varied. For the purpose, several compounds of the laboratory-scale nitrificaiion bioreactor and full-scale $A_2O$ wastewater treatment plant and their distribution of NOB were analyzed and compared. The analysis showed that Nitrobacter was the dominant NOB in nitrification bioreactor where average nitrite was maintained at 5 mg-N/L with very low organic concentration in aerobic condition, whereas Nitrospira was the dominant NOB in full-scale $A_2O$ plant where nitrite was maintained very low and organic compounds were maintained relatively high in alternating aerobic-anoxic condition. The result indicates that nitrite concentration is more critical factor than organics and dissolved oxygen which determines the dominant NOB in nitrification system and it is confirmed that Nitrospira and Nitrobacter showed the characteristics of r-strategist and K-strategist, respectively.

• Journal of the Korean Chemical Society
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• v.12 no.1
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• pp.35-38
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• 1968

Radio iodination of various aromatic derivatives (aniline, toluene, iodobenzene, acetanilide, benzene, benzoic acid) were achieved at low temperature by a chloroamine-T procedures in presence of polar solvent(dioxane). Organic base (piperidine) was used as the catalyst. Iodine replacement reaction had occured on the aromatic or alicyclic ring by this reaction, and the kind and ratio of iodinated products were proved to be different from those of usual iodide reaction in organic solvent at low temperature. The reactivity of various aromatic or alicyclic compounds towards the present iodination system was evaluated and the scope and limitation of the present procedures in the preparation of radio pharmaceuticals were discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.211-212
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• 2023

Polishing tiles among porcelain tiles are more durable and aesthetic than ceramic tiles, so their demand has recently increased. In particular, since polishing tiles have a very low absorption rate, organic adhesives with chemical bonds are mainly used. However, organic adhesives have low economic efficiency and some volatile organic compounds (TVOCs). Therefore purpose of this study was to evaluate the performance of polishing tile adhesion by developing organic-inorganic adhesives, which have chemical bonds and mechanical bonds. As a result, since the amorphous chain and chemical bonds of the polymer in the tile adhesives, both tensile and shear adhesion strength were satisfied with the KS L 1592, KS L 1593, and the rate of length change itself in the thermal cycling was lower than organic adhesives. So it is thought that it is possible to replace some organic adhesives.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.11a
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• pp.57-59
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• 1998

The headspace method has been acknowledged as a cost-effective and convenient method to analyze volatile organic compounds(VOCs) in soil. The headspace analysis is based on equilibrium partitioning of VOCs among water, air and soil in a closed system. However, the headspace method cannot be applied to soils where most of the VOCs remain sorbed even at high temperature. In this study, it was investigated how the sorption characteristics of VOCs varied with soil with different organic carbon contents and temperature. This study showed that all the VOCs were volatilized, not sorved, only in the soil with 5% organic carbon at 45$^{\circ}C$ or higher. Some fraction of VOCs remained in soil with 8% organic carbon at $65^{\circ}C$ of higher. Most of the VOCs remained sorbed in soil with 12% organic content even at 95$^{\circ}C$. This result suggested that the headspace method can be applied only to soils with little organic carbon content (less than 5%). In this case, 45$^{\circ}C$ seems to be high enough to volatilize all the VOCs from soil. Large particles still showed a significant sorption capacity for VOCs from soil. Large Particles still showed a significant sorption capacity for VOCs despite of their low level of organic carbon content. It was also shown that the organic carbon sorption coefficients (Koc) of VOCs varied with soils with different organic carbon content. This suggests that not only the organic matter content of soil but also the property of the organic matter in soil influence the sorption of VOCs to soil.

• Journal of Environmental Science International
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• v.15 no.10
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• pp.929-933
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• 2006

Indoor air quality is the dominant contributor to total personal exposure because most people spend a majority of their time Indoors. Especially when indoor environments have sources of contaminants, exposure to in-door air can potentially pose a greater threat than exposure to ambient air. In this study, estimations of volatile organic compounds and formaldehyde omission rate in indoor environments of new apartments were carried out using mass balance model in indoor environment, because indoor air quality can be affected by source generation, outdoor air level, ventilation, decay by reaction, temperature, humidity, mixing condition and so on. Considering the estimated emission rate of volatile organic compounds and formaldehyde, it Is suggested that new apartment should be designed and constructed in the aspect of using construction materials to emit low hazardous air pollutants.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.58-61
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• 2002

An alternative to pump and treat groundwater remediation is the use of reactive barriers. Zero valent iron (ZVI) is particularly useful as a reductant of chlorinated hydrocarbons because of its low cost and lack of toxicity ZVI can drive the dechlorination of chlorinated organic compounds and the reduction of chromium from the Cr(Ⅵ) to the Cr(III) state. The contaminants in subsurface environment usually exist as the mixed compounds. Therefore, the objective of this research is to study the effect of the other compounds on TCE removal by ZVI. The removal mechanism of TCE by ZVI is separated the dechlorination and sorption. TCE removal by ZVI slightly increased in presence of naphthalene as the non-reduced compound. TCE removal by ZVI remarkable decreased in presence of carbon tetrachloride, nitrate, and chromate as the reduced compounds. This research suggests that the effect of the coexisted compounds on the removal chlorinated compounds by reactive barrier technology should be considered for practical application.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1508-1512
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• 2004

A gas chromatography/mass spectrometric (GC/MS) method has been developed for the determination of trace mono-n-butyltin (MBT), di-n-butyltin (DBT), and tri-n-butyltin (TBT) compounds in sediments. Samples were extracted by 10% acetic acid in methanol containing 0.03% tropolone and were then derivatized for GC/MS analysis. Ethylation by sodium tetraethylborate and phenylation by sodium tetraphenylborate were evaluated as a derivatization reaction of the organotins in sample extract. n-Hexane was added into reaction media in the beginning of the reaction for the continuous extraction of derivatized organotins. Ethylation requires less than 2 hours to get proper derivatization yields for MBT, DBT, and TBT altogether and produces relatively low amounts of side reaction products. Compared to ethylation, phenylation requires much longer time but provides relatively lower yield and produces considerable amounts of side reaction products. Therefore, the ethylation reaction was applied for the analysis of organotin compounds in sediment. An isotope dilution mass spectrometric (IDMS) method based on GC/MS has been applied to the accurate determination of DBT compounds in the sediments. The IDMS results from the analyses of sediment samples showed a reasonable repeatability and a good agreement with the values obtained by IDMS based on liquid chromatography/induced coupled plasma/mass spectrometry.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.727-733
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• 2007

In this study, a newly developed biotrickling system, combined with a non-thermal plasma reactor, was investigated to effectively treat gaseous contaminants such as VOCs (Volatile Organic Compounds). Three kinds of non-thermal plasmas (NTPs) such as a rod type dielectric barrier discharge (DBD) plasma, a packed bead type DBD plasma and a gliding arc (GA) plasma, were tested and compared in terms of power consumption. The rod type DBD plasma was selected as one for integration with biotrickling system due to its relatively high VOC removal efficiency, low power consumption and low pressure drop. Toluene and xylene as representatives of VOCs were used as test gases. The experiment results showed that the efficiency of biotrickling system was especially very low at the high gas concentration and high flow rate and the removal efficiencies of VOCs were considerably enhanced in the biotrickling system, when the DBD plasma was worked in front of that even at the high gas concentration and high flow rate.