• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.821-827
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• 2014

The 4major river project has caused changes in flow and water quality patterns in major rivers in Korea including the Nakdong River where several toxicant release accidents have had occurred. Three dimensional hydrodynamic model, the Environmental Fluid Dynamics Code (EFDC), was applied to evaluate the effect of geomorphological change of the river on the advection and dispersion patterns of a conservative toxic pollutant. A hypothetical scenario was developed using historical data by assuming a toxic release from an upstream location. If there is a toxic release at the Gumi Industrial Complex, the toxic material would be detected after 2.22 and 9.83 days at Chilgok and Gangjung weir, respectively, in the new river system. It was estimated that they took at least 12 times longer than those with the river conditions before the project. Effect of relocation of intake towers for Daegu Metro City to upstream of Gumi City was also evaluated using the developed modeling system. It was observed that hydraulic residence time would be increased due to decreased flow rate and thus due to lowered water level. However, peak concentration differences were found to be about 2% lower in both places due to increased dispersion effect after the relocation.

• Korean Journal of Environmental Biology
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• v.34 no.2
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• pp.116-123
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• 2016

The ecotoxicity tests for metal plating wastewater were conducted using Daphnia magna (D. magna) and Euglena agilis (E. agilis). Evaluation for sources of toxicity was performed by 1) Correlation analysis between the concentration of individual metals in the metal plating wastewater and the toxic effects on D. magna, 2) Toxicant identification evaluation methods including graduated pH method, EDTA procedure and sodium thiosulfate procedure, 3) Comparison of toxic effect value ($EC_{50}$ or $LC_{50}$) of individual metal on D. magna and it's concentration in the metal plating wastewater. To evaluate the possibility of E. agilis, a Korean domestic organism, as a test model organism for metal plating waste water, E. agilis toxicity test was also assessed using on-line euglena ecotoxicity system (E-Tox system). Based on toxicant characterization test using D. magna, it was expected that SS, oxidants and heavy metals are responsible for toxicity of metal plating waste water. Especially Cu, Hg, and Ag were the major cationic metals that caused toxicity. E. agilis is less sensitive than D. magna based on the $EC_{50}$ value however it shows prompt response to toxic test substances. E. agilis shows even a significant effect on the cell swimming velocity within 2 min to toxic metal plating wastewater. Our study demonstrates that E. agilis test can be a putative ecotoxicity test for assessing the quality of metal plating waste water.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2003.05a
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• pp.150-151
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• 2003

Benzoyl peroxide is a high production volume chemical, which was produced about 1,375 tons/year in Korea as of 2001 survey. Most of them are used as initiators in polymerization, catalysts in the plastics industry, bleaching agents for flour and medication for acne vulgaris. The substance is one of the sever chemicals of which human and environmental risks are being assessed by National Institute of Environmental Research under the frame of OECD SIDS Program. It has a melting point of 104-106 $^{\circ}C$ and has solubility of 9.1 mg/1 in water at 25 $^{\circ}C$. The substance was readily biodegradable (83 % after 21days) and had toxic effects to aquatic organisms. The range of 72 hr-EbC50 (biomass) for algae was 0.07-0.44 mg/1 and 48 hr-EC50 for daphnia was 0.07-2.91 mg/1. The LC50 of acute toxicity to fish was 0.24-2.0 mg/1. Although the toxic effects of benzoyl peroxide to aquatic organisms were investigated, environmental monitoring data were not studied. In this study, distribution of the chemical among multimedia environment was estimated using EQC model based on the physical-chemical properties to evaluate the risk of benzoyl peroxide in environment. In level I, II calculation the chemical was distributed to soil (68.3 %) and water (28.7 %). In level III calculation it was primarily distributed to soil (99.9 %) and overall residence time of 3.4 years was estimated. Benzoyl peroxide could be persistent in environment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.3
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• pp.119-128
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• 1988

The purpose of this research is to quantify the effects of water content(0.3~1.255%) and temperature ($4{\sim}40^{\circ}C$) on the equilibrium distribution of toxic organic pollutant in unsaturated soil. The priority pollutants, Dichloromethane and 1, 1, 1-Trichloroethane were selected as toxic organic pollutants and the Korean decomposed granite soil as the experimental soil media. Two models were developed on the basis of shapes of soil water distribution in unsaturated soil and compared; complete surface coating(model I) vs. spot clustering (model II). From the experiment, a large decrease in the values of effective partition coefficient ($K_{eff}$) was observed as the water content increased. As the temperature increased, the $K_{eff}$ values decreased, and this effect was magnified at lower water contents. The values of $K_{eff}$ were correlated better with the estimated values using model II. Thus it was experimentally proved that the soil water tends to enclose the soil grain partly at lower water contents.

• Journal of fish pathology
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• v.36 no.2
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• pp.415-422
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• 2023

In veterinary medicine for mammals, studies are being conducted to confirm the effects of antioxidants using pathological toxicity model studies, and are also used to confirm the effect of mitigating liver or kidney toxicity of specific substances. It was considered necessary to study such a toxicity model for domestic farmed fish, so thioacetamide (TAA), a toxic substance that causes tissue damage by mitochondrial dysfunction, was injected into rainbow trout (Oncorhynchus mykiss), a major farmed freshwater fish species in Korea. The experiment was conducted with 40 rainbow trout (Oncorhynchus mykiss) weighting 53 ± 0.6 g divided into two groups. Thioacetamide(TAA) 300mg/kg of body weight was intraperitoneally injected into rainbow trout and samples were taken 1, 3, 5, 7 days after peritoneal injection. As a result, in serum biochemical analysis, AST levels related to liver function decreased 3 and 5 days after intraperitoneal injection and increased after 7 days, and ALT levels also increased after 7 days. In addition, creatinine related to renal malfunction increased 3 and 5 days after TAA injection. In histopathological analysis, pericholangitis and local lymphocyte infiltration were observed in the liver from 1 day after intraperitoneal injection of TAA, and hepatic parenchymal cell necrosis was also observed from 3 days after intraperitoneal injection. Hyaline droplet in renal tubular epithelial cell was observed from 1 day after TAA injection, and acute tubular damage such as tubular epithelial cell necrosis appeared from 3 days after TAA injection. Accordingly, it is thought that it will be able to contribute to studies that require a toxicity model.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2175-2185
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• 2000

Respiration rate should be a reasonable state variable for the activated sludge and could be used to simulate the performance of the activated sludge process. Toxic materials are classified into three groups, competitive, noncompetitive and uncompetitive. They increase/decrease the half saturation coefficient or specific growth rate. that means decreasing of the substrate removal capacity. In this research, a pilot-scale activated sludge process was operated under extended aeration method, and a representative noncompetitive inhibitor, acidic wastewater was applied to establish a respirometry-based toxicity model. Using this model. the correlation coefficient between measured and calculated respiration rate was 0.96 when acidic wastewater(pH 3.9~5.5) was introduced continuously to the aeration tank. Even though respiration rate was decreased by toxic effect of acidic wastewater, effluent substrate concentration represented to COD was deteriorated just a little bit. It might be caused by the low ratio of readily biodegradable substrate in the input substrate. Reduction of respiration rate by decreasing of input substrate concentration was much lower than that by acidic wastewater, and hence it was estimated that the possibility of false toxic alarm caused by decreasing of substrate concentration should be low.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.2
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• pp.84-91
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• 2000

Mycopasma contamination of tissue culture cells easily evades detection and, thus, represents a continous therat to cell biologists. In case where infected cell can not simply be replaced, attempts have to be made to eradicate mycoplacma from the tissue culture cells. A variety of anti-microbial agents have been shown to be toxic to mycoplasma strains ; however, cell associated mycoplasma are often protected from antibiotics at concentrations shown to be effective in vitro. Antibiotic concentrations high enough to be lethal to cell as sociated mycoplasmas frequently are also detrimentrations to the host cells, while moderately increased antibiotic levels tolerated by the host cells often lead to only temporary growth suppression and/or to the emergence of mycoplasma strains resistanct even to high concentrations of the antibiotis applied. Hare, a genetic approach for the elimination of mycoplasma from tissue culture cells that overcomes thens limitations is described. By expression of a selection marker conferring resistance to an otherwise toxic agent, Acholeplasma laidlawii infected BHK-21 cells used as the model system were enabled to temporarily tolerate antibiotic concentrations high enough to be lethal to cell associated mycopalsma while leaving the host cells unharmed. Upon successful mycoplasma eradicated, cultvation of the cured host cells in the absence of the selective agent yielded revertant cell clones that had regained susceptibillity to the toxic agent. Cressation of the selection marker expression was shown to result from the loss of the selection marker DNA, which is a consequence of the fact that the stable and permanent integration of foreign DNA in eucaryotic cell chrosomes is highly inefficient. Thus, the cells were cured from mycoplasma yet remained biochemically unaltered.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.867-874
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• 2021

Epalrestat (EPS) is a brain penetrant aldose reductase inhibitor, an approved drug currently used for the treatment of diabetic neuropathy. At near-plasma concentration, EPS induces glutathione biosynthesis, which in turn reduces oxidative stress in the neuronal cells. In this study, we found that EPS reduces neurodegeneration by inhibiting reactive oxygen species (ROS)-induced oxidative injury, mitochondrial membrane damage, apoptosis and tauopathy. EPS treatment up to 50 µM did not show any toxic effect on SH-SY5Y cell line (neuroblastoma cells). However, we observed toxic effect at a concentration of 100 µM and above. At 50 µM concentration, EPS showed better antioxidant activity against H₂O₂ (100 µM)-induced cytotoxicity, ROS formation and mitochondrial membrane damage in retinoic acid-differentiated SH-SY5Y cell line. Furthermore, our study revealed that 50 µM of EPS concentration reduced the glycogen synthase kinase-3 β (GSK3-β) expression and total tau protein level in H₂O₂ (100 µM)-treated cells. Findings from this study confirms the therapeutic efficacy of EPS on regulating Alzheimer's disease (AD) by regulating GSK3-β and total tau proteins phosphorylation, which helped to restore the cellular viability. This process could also reduce toxic fibrillary tangle formation and disease progression of AD. Therefore, it is our view that an optimal concentration of EPS therapy could decrease AD pathology by reducing tau phosphorylation through regulating the expression level of GSK3-β.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.513-517
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• 2007

This study is to establish the appliance model for the automatic fire alarm system in clean room within the framework of the performance based design. Because of the environmental and dimensional characters of clean room, this space is exposed to fire and toxic damage, so it is very important to notify the occupants of these dangerous situations.

• Korean Journal of Plant Tissue Culture
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• v.27 no.5
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• pp.395-399
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• 2000

The phytoremediation of trinitrotoluene, nitroglycerine, pentaerytritoltetranitrate in plant tissue cultures of Solanum aviculare, Rheum palmatum and Populus simonii were studied. All above mentioned explosives were degradated to to less toxic products and finally mineralized or bound to the cell wall.