• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.2
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• pp.1-18
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• 1999

The purpose of this study was to compare performances of two analytical methods, the OSHA 42 and the NIOSH 5522, of quantifying total isocyanates in air. These methods were compared in terms of accuracy and precision and the detection limits using four(4) spiked samples in each of four(4) concentration levels which ranged from 0.25 to 2.0 times of the ACGIH TLV-TWA. In addition, two methods were used to as sess airborne concentrations of total isocyanates at the following processes including autobody spray painting, furniture spray painting, polyurethane foaming, urethane adhesion, UV coating, and pigment mixing. The results of this study showed that the NIOSH 5522 method was better than the OSHA 42 method in terms of accuracy, precis ion, and detection limit for quantifying airborne total isocyanates. It was also clear that the NIOSH method was capable of detecting not only monomeric but also non-monomeric isocyanates. The results of air concentrations of total isocyanates among processes studied indicate that some processes may exceed the recommended level of isocyanates. In addition, to evaluate toxicological effects of total isocyanates, it is recommended to consider additive effects of isocyanates present in mixtures.

• The Journal of Natural Sciences
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• v.8 no.2
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• pp.21-26
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• 1996

Commercially available Chines oriental lacquer was treated to get two fractions, hexane soluble fraction and hexane insoluble fraction. Hexane soluble fraction was subjected to thermal curing process. Films obtained from the lacquer under normal conditions and obtained from thermal curing were compared. The compounds in hexane soluble fraction were copolymerized with 1,6-diisocyanohexane, and toluendiisocyanate(TDI). Films obtained by thermal curing were highly brittle and hydrophobic while the films obtained under normal conditions were hydrophilic. Curing reaction did not occur when oxygen was not available.Some of the major component in the lacquer was isolated by HPLC and UV spectrum of each compound was recorded.

• Textile Coloration and Finishing
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• v.23 no.2
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• pp.131-139
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• 2011

This study surveyed on the synthesis of one-step type hydrophilic non-porous PU resin and the physical property of the coated fabric for the garment. Three kinds of chain extender such as MEG, 1,4-BD and NPG were used for the preparation of one-step type hydrophilic non-porous PU resin in order to examine the effect of chain extender on the physical properties of PU-coated fabric. And the effects of isocyanate on the physical properties of PU coated fabric were surveyed by mixing with various TDI and MDI ratios. In addition, the physical properties of the coated fabric treated with one-step type hydrophilic non-porous PU resin were examined according to the pre-treatment conditions such as cire finishing. Finally, the washing durability of the coated fabrics was assessed. The coated fabrics treated with PU resin synthesized with PEG1000, MEG and TDI/MDI (6/4) showed the best physical properties. Considering the pre-treatment conditions, best performance of hydraulic pressure, water vapor permeability, and water repellency were obtained with top roller rotation ratio of 150% under 50 ton pressure at $170^{\circ}C$.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.95-106
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• 2009

The Shihwa constructed wetland was established for the treatment of severely poluted water from Banwoul, Donghwa and Samhwa streams. This study was focused on investigating the structure of epiphytic diatom communities on reed (Phragmites communis) planting area at Banwoul high wetland (3 stations) and low wetland (3 stations) from March to October 2005. The concentration of T-N of inlet stations from the streams were decreased by flowed through the wetland, but the concentration of T-P were increased at outflow part. Epiphytic diatoms on the reed were a total 109 taxa which were composed of 103 species, 5 varieties, 1 unidentified species. The standing crops were rapidly decreasing tendency from spring to autumn but chlorophyll-a concentration were showed a very irregulated changes. Dominant species were 6 taxa which were Achnanthes minutissima in the early investigation, and were changed to the genus Navicula and the genus Nitzschia in the summer. DAIpo were ranged the values of $20.2{\sim}51$, which were mesosaprobic states at the high wetland and ranged the values of $12.4{\sim}52$, which were polysaprobic to mesosaprobic states at the low wetland. TDI were ranged the values of $28.8{\sim}94.5$, which were oligotrophic to eutrophic state at the high wetland and ranged the values of $33.3{\sim}89.7$ which were mesotrophic to eutrophic states at the low wetland. The healthy assessment (DAIpo and TDI) of water ecosystem were showed clean-bad from spring to autumn. These epiphytic diatom communities were determinated by the biological factor such as the growth of reed and the physical factors such as water temperature, light penetration and SS and so on.

• Journal of Korea Water Resources Association
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• v.51 no.10
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• pp.863-874
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• 2018

The purpose of this study is to evaluate the future climate change impact on stream aquatic ecology health of Han River watershed ($34,148km^2$) using SWAT (Soil and Water Assessment Tool) and random forest. The 8 years (2008~2015) spring (April to June) Aquatic ecology Health Indices (AHI) such as Trophic Diatom Index (TDI), Benthic Macroinvertebrate Index (BMI) and Fish Assessment Index (FAI) scored (0~100) and graded (A~E) by NIER (National Institute of Environmental Research) were used. The 8 years NIER indices with the water quality (T-N, $NH_4$, $NO_3$, T-P, $PO_4$) showed that the deviation of AHI score is large when the concentration of water quality is low, and AHI score had negative correlation when the concentration is high. By using random forest, one of the Machine Learning techniques for classification analysis, the classification results for the 3 indices grade showed that all of precision, recall, and f1-score were above 0.81. The future SWAT hydrology and water quality results under HadGEM3-RA RCP 4.5 and 8.5 scenarios of Korea Meteorological Administration (KMA) showed that the future nitrogen-related water quality in watershed average increased up to 43.2% by the baseflow increase effect and the phosphorus-related water quality decreased up to 18.9% by the surface runoff decrease effect. The future FAI and BMI showed a little better Index grade while the future TDI showed a little worse index grade. We can infer that the future TDI is more sensitive to nitrogen-related water quality and the future FAI and BMI are responded to phosphorus-related water quality.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.777-789
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• 2019

The purpose of this study is to evaluate changes in water quality and aquatic ecosystem health by additional dam release of stream maintenance flow from multipurpose dams in Han river basin ($34,148km^2$) using SWAT (Soil and Water Assessment Tool). The period of additional release was spring (April to June) and autumn (August to October) to evaluate the changes with the data of aquatic ecosystem health survey. The amount of additional release was set proportional to the present dam release, and the maximum release amount was controlled not to exceed the officially notified stream maintenance flow from dam. The 10 percent to 50 percent additional releases showed that the stream water quality (T-N, $NH_4$, T-P, and $PO_4-P$) concentrations except $NO_3-N$ decreased in spring while increased in autumn period. Using the stream water quality results and applying with Random Forest algorithm, the grade of aquatic ecosystem health index (FAI, TDI, and BMI) was improved for both periods especially in the downstream of basin. This study showed that the additional release of stream maintenance flow was more effective in spring than autumn period for the improvement of water quality and aquatic ecosystem.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.531-537
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• 2012

The information about the physicochemical environments, the species distribution and community of the epilithic diatom cells in Pyengchang river and inflow streams of Gangwon-do were studied for assessment of biological water quality from June 2008 to October 2010. Total 112 diatom taxa were identified with 2 orders, 9 families, 26 genera, 95 species and 17 varieties. Among the total taxa identified, 13 taxa, 52 taxa and 15 taxa represented the family Achnanthaceae, Naviculaceae and Bacillariaceae, respectively. The pH values of the water was found to be neutral to alkaline due to the limestone grounds of Pyengchang river and inflow streams. The 13 taxa including Epithemia adnata, belonged to alkaline-water diatoms, and three species - Cymbella japonica, Eunotia major and Fragilaria capitellata - are known to be acidic-water species. The species, Hannaea arcus, known as a cryophilic and mountain periphyton was identified at IF2, IF3 and IF4 in low water temperature environments at high altitudes, being a dominating species in P1 and IF1. Four saproxenous species - Achnanthes convergens, Cocconeis placentula var. lineata, Cymbella turgidula and Hannaea arcus - were dominant at some sampling sites. For biological water quality assessment, IF2, IF3 and P3 showed low water quality class. The values of DAIpo and TDI were 10.6 ~ 98.0 and 13.8 ~ 94.2, respectively. Therefore, biological water quality in Pyengchang river and inflow streams was relatively desirable.

• Journal of Dairy Science and Biotechnology
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• v.27 no.1
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• pp.1-12
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• 2009

In 2008, baby formula containing melamine was found to be responsible for a large outbreak of renal failure in infants in China. A total of 294,000 infants were hospitalized, and at least 6 babies died due to ingestion of the tainted formula. Melamine contains high levels of nitrogen (>60%), which is used as an indicator of protein content. Therefore, high levels of melamine in infant formula were thought to be the result of deliberate contamination m an attempt to increase its apparent protein content. Following inspections by China's national inspection agency, assorted products from at least 22 dairy manufacturers across China were found to have varied levels of melamine (range: 0.096196.61 mg/kg). Melamine co-exposure with cyanuric acid can induce acute melamine-cyanurate crystal nephropathy, which can lead to renal failure at much lower doses than if either compound were ingested alone. However, currently, there are very few data on melamine analogues other than cyanuric acid. At an expert meeting of the WHO and FAO held to review toxicological aspects of melamine and cyanuric acid on December 14, 2008, a new tolerable daily intake (TDI) of melamine was established that could be applied to the entire population, including infants. Therefore, a risk assessment of the various theoretical melamine contamination levels in infant formula and selected representative foods (other than infant formula and sole-source nutrition products) is urgently needed for Korean babies and children up to 7 years of age. Although the undetectable level regulation for infant formula may be low enough to guarantee the safety of babies under the age of 1 year (including premature babies), the melamine standard of 2.5 ppm for foods other than baby formula could be insufficient to protect the 95th percentile population aged 1~2 years because of this demographic's high consumption of milk, yogurt, and soy milk (hazard index = 1.79). Because TDIs are chronic values intended to protect an individual over his/her lifetime, occasional modest ingestion in excess of the TDI is not likely to be a health concern. However, children aged 1~2 years may have renal systems that are comparatively more sensitive to the crystallization of melamine and its analogues. Therefore, governmental jurisdictions may need to practice more prudent management of food items that could raise the melamine exposure for this population.

• Korean Journal of Environmental Biology
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• v.29 no.3
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• pp.180-194
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• 2011

In this study, We were investigated the interrelationships between epilithic diatom communities and physico-chemical factors at Banbyeon stream, Gilan stream and Nakdong river in the Lake Imha basin from September 2008 to June 2009. Epilithic diatom communities were identified a total 120 taxa which were composed to 2 Orders, 3 Suborders, 7 Families, 22 Genera, 108 species and 12 varieties. The dominant species were 4 taxa, which were Achnanthes alteragracillima, A. convergens, A. minutissima and Fragilaria construens var. venter during the investigation periods at 8 sites. Correlation coefficients between epilithic diatom communities and physicochemical factors were from -0.94 to 0.97. Correlation coefficients (r) between turbidity, QHEI and density, species number and indices of diatom communities were from -0.18 to 0.42 which was showed lower values than the values of chemical factors. Correlation coefficients (r) between QHEI and Epilithic diatom communities were showed the low values. Correlation coefficients (r) between TP and diatom indices (DAIpo, TDI) were 0.79 and 0.78, respectively. Therefore, epilithic diatom communities were greatly influenced by TP.

• Polymer(Korea)
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• v.24 no.6
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• pp.744-750
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• 2000

Oil gelling agent was synthesized with PPG, PTMG and TDI at 7$0^{\circ}C$ for 4hours. PPGs and PTMGs having various average molecular weights (M$_{n}$: 1000, 2000, 3000) were employed to investigate the ratio of oil gelation and water gelation. As M$_{n}$ of PPG, in result, was decreased from 3000 to 1000, the ratio of oil gelation was increased from 130% to 290% for PPG and from 250% to 310% for PTMG. Ratio of oil gelation was increased approximately two times when EG was added. As the amount of hydrophilic compound in the prepolymer was increased, ratio of oil gelation was increased from 290% to 1120% for PPG and increased from 310% to 1310% for PTMG, due to the increased dispersion of prepolymer in the water/oil mixture.ure.