• Journal of Plant Biotechnology
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• v.36 no.3
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• pp.219-223
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• 2009

Oxidative stress derived from excess reactive oxygen species (ROS) is a major damaging factor for plants exposed to environmental stresses. Sweetpotato [Ipomoea batatas (L.) Lam] has a relatively broad adaptability to harsh environmental conditions compared to other staple crops. In this study, to select stress-tolerant sweetpotato cultivars for sources of molecular breeding on marginal lands, we evaluated the ion leakage values in 10 different cultivars after treatment of methyl viologen (MV), an ROS-generating nonselective herbicide, to leaf discs. DPPH radical scavenging activity and the contents of total phenolics were also investigated. The ion leakage of each cultivar showed a diverse value, which is well correlated with DPPH radical scavenging activity of each cultivar. DPPH radical scavenging activity also showed a high corelation with the contents of total phenolic contents. Three cultivars of Yanshu 8, Shinhwangmi and Shinzami showed high antioxidant activity. Our results suggest that a simple and efficient DPPH radical scavenging activity would be a suitable method to select potential cultivars with enhanced tolerance to multiple environmental stress.

• Environmental Engineering Research
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• v.23 no.3
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• pp.339-344
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• 2018

The Cu loading of a cubic $Ce_{0.8}Zr_{0.2}O_2$-supported Cu catalyst was optimized for a single-stage water gas shift (WGS) reaction. The catalyst was prepared by a co-precipitation method, and the WGS reaction was performed at a gas hourly space velocity of $150,494h^{-1}$. The results revealed that an 80 wt% $Cu-Ce_{0.8}Zr_{0.2}O_2$ catalyst exhibits excellent catalytic performance and 100% $CO_2$ selectivity ($X_{CO}=27%$ at $240^{\circ}C$ for 100 h). The high activity of 80 wt% $Cu-Ce_{0.8}Zr_{0.2}O_2$ catalyst is attributed to the presence of abundant surface Cu atoms and the low activation energy of the resultant process.

• Journal of Environmental Health Sciences
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• v.43 no.2
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• pp.157-166
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• 2017

Objectives: Exposure to hazardous air pollutants could be affected by sociodemographic factors such as age, gender and more. Information on time spent in microenvironments has a critical role in exposure assessment. The purpose of this study was to analyze the exposure pathways which influence personal exposure through time-activity patterns and sociodemographic factors. Methods: A total of 379 subjects were collected from the second term of the Korean National Environmental Health Survey. A questionnaire survey in relation to sociodemographic factors and a time-activity diary were carried out for personal exposure to toluene. Focusing on personal exposure to toluene, factors affecting personal exposure were analyzed using multiple regression analysis. Results: Participants spent their time in an indoor house for $16.8{\pm}4.0hr$, workplace or school $2.3{\pm}3.5hr$, and other indoor $2.1{\pm}2.2hr$. Sociodemographic factors were significantly different among each personal exposure and microenvironment. Time of staying at an office turned out to be a main factor from point of exposure in exposure pathway using multiple regression analysis. As a result, this means that exposure may be different according to the time of staying in each microenvironment. Conclusions: Personal exposure to air pollutants might be decided by time-activity pattern indicating when, where, and which activities people pursue, as well as individual sociodemographic factors.

• Proceedings of the Korean Society of Toxicology Conference
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• 2005.05a
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• pp.85-90
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• 2005

Diesel exhaust Particles (DEPs) are known to induce allergic responses in airway epithelial cells, such as the production of various cytokines via nuclear factor-kappa B ($NF-{\kappa}B$). However. the intracellular signal transduction pathways underlying this phenomenon have not been fully examined. This study showed that DEP induced $NF-{\kappa}B$ activity via transforming growth factor-${\beta}$ activated kinase 1 (TAK1) and $NF-{\kappa}B$-inducing kinase (NIK) in L2 rat lung epithelial cells. DEP induced the $NF-{\kappa}B$ dependent reporter activity approximately two-to three-fold in L2 cells. However, this effect was abolished by the expression of the dominant negative forms of TAK1 or NIK. Furthermore, it was shown that DEP induced TAK1 phosphorylation in the L2 cells. These results suggest that TAK1 and NIK are important mediators of DEP-induced $NF-{\kappa}B$ activation.

• Journal of Environmental Impact Assessment
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• v.9 no.3
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• pp.203-214
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• 2000

Health risk assessment is applied to streamlining LCA(Life Cycle Assessment) using Monte carlo simulation for probabilistic/stochastic exposure and risk distribution analysis caused by data variability and uncertainty. A case study was carried out to find benefits of this application. BTC(Benzene, Trichloroethylene, Carbon tetrachloride mixture alias) personal exposure cases were assumed as production worker(in workplace), manager(in office) and business man(outdoor). These cases were different from occupational retention time and exposure concentration for BTC consumption pattern. The result of cancer risk in these 3 scenario cases were estimated as $1.72E-4{\pm}1.2E+0$(production worker; case A), $9.62E-5{\pm}1.44E-5$(manger; case B), $6.90E-5{\pm}1.16E+0$(business man; case C), respectively. Portions of over acceptable risk 1.00E-4(assumed standard) were 99.85%, 38.89% and 0.61%, respectively. Estimated BTC risk was log-normal pattern, but some of distributions did not have any formal patterns. Except first impact factor(BTC emission quantity), sensitivity analysis showed that main effective factor was retention time in their occupational exposure sites. This case study is a good example to cover that LCA with probabilistic risk analysis tool can supply various significant information such as statistical distribution including personal/environmental exposure level, daily time activity pattern and individual susceptibility. Further research is needed for investigating real data of these input variables and personal exposure concentration and application of this study methodology.

• Environmental Analysis Health and Toxicology
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• v.23 no.2
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• pp.67-77
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• 2008

It has been observed that the linear relationship between the logarithm of bioconcentration factor (log BCF) of highly hydrophobic chemicals and their log $K_{ow}$ breaks when log $K_{ow}$ becomes greater than 6.0. Consequently, super hydrophobic chemicals were not thought to cause baseline toxicity as a single compound. Researchers often call this phenomenon as "hydrophobicity cutoff" meaning that bioconcentration or corresponding baseline toxicity has a certain cutoff at high log $K_{ow}$ value of hydrophobic organic pollutants. The underlying assumption is that the increased molecular size with increasing hydrophobicity prohibits highly hydrophobic compounds from crossing biological membranes. However, there are debates among scientists about mechanisms and at which log $K_{ow}$ this phenomenon occurs. This paper reviews three hypotheses to explain observed "cutoff": steric effects, kinetic or physiological limitations, and chemical activity cutoff. Although the critical molecular size that makes biological membranes not permeable to hydrophobic organic chemicals is uncertain, size effects in combination with kinetic limitation would explain observed non-linearity between log BCF and log $K_{ow}$. Chemical activity of hydrophobic chemicals generally decreases with increasing melting point at their aqueous solubility. Thus, there may be a chemical activity cutoff of baseline toxicity if there is a critical chemical activity over which baseline effects can be observed.

• Journal of Korean society of Dental Hygiene
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• v.10 no.5
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• pp.887-895
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• 2010

Objectives : In this study, 233 dental hygiene students in Seoul and Gyeonggi areas were surveyed in order to provide the basic data for more effective clinical practice by investigating the stress they experience during the clinical practice and how they cope with stress; Methods : 5 areas in stress factors as environmental factor, interpersonal factor, role and activity, ideal and value, and the amount of BEPSI and 4 areas in their coping methods as problem-oriented, social support, emotion-oriented, and wishful thinking were measured by Liker 5-point scale. Results : 1. The satisfaction level of subjects on their major was the highest as 'generally satisfied (50.6%),' and their satisfaction level of clinical practice was also the highest as 'generally satisfied (32.6%).' 2. The clinical practice stress was 2.76 points on average, and their stress factors were ideal and value (3.18), environmental factor (2.98), role and activity (2,70), the amount of BEPSI (2.55), and interpersonal factor (2.37). And the way how they cope with stress were 3.29 points on average, wishful thinking (3.71), social support (3.36), problem-oriented (3.13), and emotion-oriented (2.95). 3. The clinical practice stress according to clinical training institutions showed significant differences: university dental hospitals and general hospitals (2.83), dental clinics (2.65), and dental hospitals (2.63). 4. The clinical practice stress showed a negative correlation between the satisfaction level of major and the satisfaction level of clinical practice (p<0.01), and the more satisfaction they had in their major and clinical practice, the less stress during the clinical practice. 5. In the correlation between each subordinate factor of the stress in clinical practice and how to cope with it, interpersonal factor and emotion-oriented factor, the amount of BEPSI and wishful thinking showed a positive correlation (p<0.05). Conclusions : In this study, it is necessary to develop clinical practice program that is to increase satisfaction and provide motivation in order to reduce the stress during clinical training.

• Environmental Analysis Health and Toxicology
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• v.14 no.1_2
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• pp.45-54
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• 1999

Quantitative strucrure-activity relationships between the toxicity (LD$\_$50/) and molecular properties of amine and nitro compounds were tested. The all 19 compounds showed low correlations below 0.500 to their LD$\_$50/ values. When amine or nitro compounds were taken separately, the correlation between the calculated chemphysico parameters and LD$\_$50/ were also poor (r$^2$=0.4911, 3967 repectively). The overall relationships among the QSAR parameters were investigated. Molecular weight shows a high correlation with total surface area (r$^2$=0.9287); 0.9090 for zero-order connectivity and second-order connectivity : 0.8784 for bioconcentration factor and second-order connectivity. When amine compounds were taken to perform the statistical treatment, the relationships between parameters were as follows: 0.8436 for volume-negentropy; 0.8925 for volume-bioconcentration factor; 0.9929 for zero-order connectivity-Kow; zero-order connectivity-bioconcentration factor; 0.9141 for zero-order connectivity-solubility; 0.9718 for solubility-bioconcentration factor; 0.9894 for solubility-bioconcentration factor and 0.9319 for Kow-bioconcentration factor. On the other hand, nitro compounds showed different relationships as follows: 0.8952 for volume-I/O character; 0.9520 for volume-total surface area: 0.9351 for volume-molecular weight; 0.9351 for volume-MW; 0.9961 for Kow-Koc; 0.8455 for Kow-bioconcentration factor; 0.8879 for Koc-bioconcentration factor; 0.9987 for MW-total surface area respectively.

• Food Science and Biotechnology
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• v.17 no.2
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• pp.367-372
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• 2008

Cellular protection against carcinogens could be achieved by the induction of phase 2 detoxifying and antioxidant enzymes such as glutathione S-transferase (GST), NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase 1 (HO1). Nuclear transcription factor E2-related factor 2 (Nrf2) binds to antioxidant response element (ARE) in the promoter region of these genes and the resulting transactivation occurs. In the present study the effect of gujeolcho (Chrysanthemum zawadskii) roots on the Nrf2-ARE pathway were investigated. C. zawadskii root extract was fractionated with a series of organic solvents and their ability to induce Nrf2-ARE pathway was examined. We separated the most potent dichloromethane (DCM) fraction into 12 sub-fractions and found several sub-fractions with strong effects on the Nrf2-ARE pathway. Fraction 4 strongly induced the ARE-reporter gene activity as well as Nrf2 expression. Sitosterol was isolated as a major compound in fraction 4 although its activity was not as potent as its mother fraction. These results indicate that C. zawadskii roots might be used as a potential natural chemopreventive source.

• Mycobiology
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• v.47 no.1
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• pp.50-58
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• 2019

Agarum clathratum, a brown macroalgae species, has recently become a serious environmental problem on the coasts of Korea. In an effort to solve this problem, fungal diversity associated with decaying A. clathratum was investigated and related ${\beta}$-glucosidase and endoglucanase activities were described. A total of 233 fungal strains were isolated from A. clathratum at 15 sites and identified 89 species based on morphology and a multigene analysis using the internal transcribed spacer region (ITS) and protein-coding genes including actin (act), ${\beta}$-tubulin (benA), calmodulin (CaM), and translation elongation factor (tef1). Acremonium, Corollospora, and Penicillium were the dominant genera, and Acremonium fuci and Corollospora gracilis were the dominant species. Fifty-one species exhibited cellulase activity, with A. fuci, Alfaria terrestris, Hypoxylon perforatum, P. madriti, and Pleosporales sp. Five showing the highest enzyme activities. Further enzyme quantification confirmed that these species had higher cellulase activity than P. crysogenum, a fungal species described in previous studies. This study lays the groundwork for bioremediation using fungi to remove decaying seaweed from populated areas and provides important background for potential industrial applications of environmentally friendly processes.