• Journal of Soil and Groundwater Environment
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• v.26 no.5
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• pp.20-28
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• 2021

Perfluorinated compounds(PFCs), an emerging environmental pollutant, are environmentally persistent and bioaccumulative organic compounds that possess a toxic impact on human health and ecosystems. PFCs are distributed widely in environment media including groundwater, surface water, soil and sediment. PFCs in contaminated solid can potentially leach into groundwater. Therefore, understanding PFCs partitioning between the aqueous phase and solid phase is important for the determination of their fate and transport in the environment. In this study, the sorption equilibrium batch and kinetic experiment of PFCs were carried out to estimated the sorption coefficient(K_d) and the fraction between aqueous-solid phase partition, respectively. Sorption branches of the PFDA(Perfluoro-n-decanoic acid), PFNA(Perfluoro-n-nonanoic acid), PFOA(Perfluoro-n-octanoic acid), PFOS(Perfluoro-1-octane sulfonic acid) and PFHxS(Perfluoro-1-hexane sulfonic acid) isotherms were nearly linear, and the estimated K_d was as follow: PFDA(1.50) > PFOS(1.49) > PFNA(0.81) > PFHxS(0.45) > PFOA(0.39). The sorption kinetics of PFDA, PFNA, PFOA, PFOS and PFHxS onto soil were described by a biexponential adsorption model, suggesting that a fast transport into the surface layer of soil, followed by two-step diffusion transport into the internal water and/or organic matter of soil. Shorter times(<20hr) were required to achieve equilibrium and fraction for adsorption on solid(F₁, F₂) increased with perfluorinated carbon chain length and sulfonate compounds in this study. Overall, our results suggested that not only the perfluorocarbon chain length, but also the terminal functional groups are important contributors to electrostatic and hydrophobic interactions between PFCs and soils, and organic matter in soils significantly affects adsorption maximum capacity than kinetic rate.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.296-305
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• 2006

The adsorption and persistence of pencycuron {1-(4-chlorobenzyl) cyclopentyl-3-phenylurea} in soils were investigated under laboratory and field conditions to in order to assess the safety use and environmental impact. In the adsorption rate experiments, a significant power function of relation was found between the adsorbed amount of pencycuron and the shaking time. Within one hour following the shaking, the adsorption amounts in the SCL and the SiCL were 60 and 65% of the maximum adsorption amounts, respectively. The adsorption reached a quasi-equilibrium 12 hours after shaking. The adsorption isotherms followed the Freundlich equation. The coefficient (1/n) indicating adsorption strength and degree of nonlinearity was 1.45 for SCL and 1.68 to SiCL. The adsorption coefficients ($K_d$) were 2.31 for SCL and 2.92 to SiCL, and the organic carbon partition coefficient, $K_{oc}$, was 292.9 in SCL and 200.5 inSiCL. In the laboratory study, the degradation rate of pencycuron in soils followed a first-order kinetic model. The degradation rate was greatly affected by soil temperature. As soil incubation temperature was increased from 12 to $28^{\circ}C$, the residual half life was decreased from 95 to 20 days. Arrhenius activation energy was 57.8 kJ $mol^{-1}$. Furthermore, the soil moisture content affected the degradation rate. The half life in soil with 30 to 70% of field moisture capacity was ranged from 21 to 38 days. The moisture dependence coefficient, B value in the empirical equation was 0.65. In field experiments, the half-life were 26 and 23 days, respectively. The duration for period of 90% degradation was 57 days. The difference between SCL and SiCL soils varied to pencycuron degradation rates were very limited, particularly under the field conditions, even though the characteristics of both soils are varied.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.1
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• pp.45-57
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• 2015

Objectives: This study aims to compare the physicochemical characteristics, toxicological data with Occupational Exposure Limits (OELs) of chemicals under the Occupational Safety and Health Act(OSHA) regulated by the Ministry of Employment and Labor of Korea. Methods: Information on chemicals which have OELs on physicochemical characteristics and toxicological data was collected using Material Safety Data Sheet(MSDS) from Korea Occupational Safety and Health Agency(KOSHA) and the Korea Information System for Chemical Safety Management(KISChem) in 2014. Statistical analyses including correlation and simple regression were performed to compare the OELs with chemical characteristics including molecular weight, boiling point, odor threshold, vapor pressure, vapor density, solubility and octanol-water partition coefficient(OWPC) and toxicological data such as median lethal dose($LD_{50}$) and median lethal concentration($LC_{50}$). Results: A total of 656 chemicals have OELs under OSHA in Korea. The numbers of chemicals which have eight-hour time weighted average(TWA) and short term exposure limits(STEL) are 618 and 190, respectively. TWA was significantly correlated with boiling point and STEL was only correlated with vapor pressure among physicochemical characteristics. Solubility and OWPC between "skin" and "no skin" substances which indicate skin penetration were not significantly different. Both $LD_{50}$ and $LC_{50}$ were correlated with TWA, while the $LC_{50}$ was not with STEL. As health indicators, health rating and Emergency Response Planning Guidelines(ERPG) rating as recommended by the National Fire Protection Association(NFPA) and American Industrial Hygiene Association(AIHA) were associated with OELs and reflect the chemical hazards. Conclusions: We found relationships between OEL and chemical information including physicochemical characteristics and toxicological data. The study has an important meaning for understanding present regulatory OELs.

• Korean Journal of Environmental Biology
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• v.22
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• pp.71-77
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• 2004

Alkylphenols (8), chlorophenols (2), bisphenol A, eoprostanols (2) and cholesterol compounds were analyzed in the surface water and surface sediment taken from Gwangyang Bay and surrounding streams in 2001. Among the target analytes, nonylphenol and dihydrocholesteyol compounds were detected with high concentration and high frequency. t-Octylphenol, bisphenol A and coprostanols were detected only in some sediment samples from the stream. The highest concentration of nonylphenol was determined in stream sample, and concentrations of nonylphenol in the inner part of Gwangyang Bay were higher than those in the out part. Nonylphenol concentrations in the surface seawater and surface sediment samples ranged from 4.0 to 74.0 ng l$\^$-1/ and from 3.1 to 74.3 ng g$\^$-1/ dry wt., respectively. Partition coefficient (LogK$\_$oc/) of nonylphenol between sediment and water was 4.8. Nonylphenol nnd dihydrocholesteol concentrations in the stream surface sediment samples ranged from 4.6 to 808.6 and from 78.4 to 1133.6 ng g$\^$-1/ dry wt., respectively. Relatively high concentrations of nonylphenol were found in the stream samples which aye flowing through industrial complex area, while dihydrocholesterol concentration was relatively high in the stream samples which are flowing through only municipal area. Seaward decreasing tyend in nonylphenol concentration was observed from the Seomjin River estuary to the Gwanyang Bay. Such trend was best supported by the strong correlation between nonylphenol concentration and salinity in water samples.

• Journal of Pharmaceutical Investigation
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• v.27 no.4
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• pp.287-293
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• 1997

To make a stable o/w emulsion, the effects of egg lecithin as an emulsifier and polyvinylpyrrolidone (PVP) as an auxiliary emulsifier on the physical stability of emulsion were investigated. The oil-in-water emulsion system was manufactured by microfluidizer and evaluated the physical stability. Average particle size and size distribution of emulsion was measured by dynamic light scattering analyzer and interfacial tension was measured. From the interfacial tension tested, critical micelle concentration of the egg lecithin was 0.1 %w/v and optimal concentration for the preparation of emulsion was 1.0 %w/v. The mean particle size was about $0.2\;{\mu}m$ which was suitable for injections. The short-term accelerated stability studies were conducted by centrifugation, freeze-thaw method and shaking of the emulsion samples. The addition of PVP was caused the reduction in the particle size and improved the physical stability of emulsion. These results suggested that a mixed interfacial film comprising the egg lecithin and PVP was formed at the o/w interface and it was effective in preventing phase separation under thermic or mechanical stress. We used antineoplaston A10 (A10) as a model drug which is peptide and amino acid derivative having a action to the living organism against the development of neoplastic growth by a nonimmunological progress. It has a poor solubility in water and there may be a difficulty in formulation of A10. Emulsion formulation study about A10 was performed. Solubility of A10 in emulsion was about five times as high as that in water. From the results of solubility and partition coefficient, almost A10 molecules in o/w emulsion exist in the interface between oil and water.

• Journal of Educational Research in Mathematics
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• v.17 no.1
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• pp.33-50
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• 2007

Positive attitude toward mathematics is gaining bigger recognition as an important contributing factor to mathematical ability. As a strategy for strengthening affective domain and betterment of mathematics teaching and loaming, classifying students by their causes for liking or disliking mathematics can be an effective way In this study the author tried to devise methods to classify students by their types of math disliking and investigate correlations between mathematical achievements and these math-disliking types from a sample group of 8th graders. To identify the types of reasons why 8th graders dislike mathematics, a questionnaire with 30 items was made firstly. Then by applying the 'Factor analysis' of SPSS, the 30 items were divided into five partitions. Through abstraction of each partition, five math-disliking types, 'Competences', 'Basics', 'Confidences', 'Usefulness', and 'Teachers' were defined. They are expected to help teachers for describing each student's tendency of math-disliking. Further, correlation coefficients between mathematical achievements and each of the five math-disliking type were investigated against 4 groups which were made from sample group by the discrimination of gender and two levels (high and low) of mathematical achievements in cognitive area. As results, the following facts were found. (i) The trends of correlations between cognitive achievement and the five math disliking types were different across the 4 groups at statistically meaningful degrees. (ii) Most of the male students who had math-disliking types were proved to be in the low achievement level. But for the female students, only 50% of students who had math-disliking types were in the low achievement level. (iii) Compared to male students, higher portion of female students had math-disliking types despite their high achievement in cognitive area.

• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.177-182
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• 1990

The changes in the partition coefficient of model proteins (lysozyme, myoglobin, conalbumin, bovine serum albumin) in an aqueous two·phase system formed by polyethylene glycol and dextran were examined in order to improve the capacity of counter current distribution (CCD) for the protein fractionation and concentration . The protein distribution pattern in CCD with 30 tubes varied with the pH (4.5, 5.5, 6.5, 9.0, 12.0) and KCl concentration (0mM, 50mM, 250mM, 500mM) of the system. From the mixture of model proteins, pure myoglobin was appeared at the upperphase of 14th tube having 50mM of KCl at pH 5.5 and the upper-phase of 13th tube having 250mM of KCl at pH 6.5. Similarly pure BSA was obtained at the 14th tube having KCl 250mM with pH 4.5, pure lysozyme at the 19th tube having 500mM of KCl at pH 4.5 and the upper-phase of 16th tube 50mM of KCl at pH 5.5.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.8
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• pp.829-835
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• 2006

The composition, source, and regional concentration of polybrominated diphenyl ethers(PBDEs) were measured in pine needles with several sites in Korea. Homologs specific analysis confirmed that hepta-BDE(bromodiphenyl ethers) through deca-BDE were predictive indicator for total PBDEs concentration(Pearson's correlation coefficient r>0.96, p<0.001). Deca-BDE were detected in relatively very high concentration compared to other PBDE congeners in all samples. The similarity of between congeners profile to those of Bromkal 70-5DE and DE-71, the commercial mixture of PBDEs, indicates these mixtures are source of PBDEs observed in these sites. Also, BDE-47, -99, -100, -206, -207, and -209 were the dominant congeners in all samples, suggesting that the widely used commercial penta- and deca-BDE technical mixture were the original sources. However, Pearson's correlation coefficients of between BDE-209 and BDE-47, -99, -100 were insignificant, which implied that tetra-BDE and penta-BDE may originate from secondary sources such as air-plant partition in manner similar to that of the PCBs, while deca-BDE formulation still has primary sources.

• The Korean Journal of Pesticide Science
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• v.17 no.2
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• pp.84-93
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• 2013

Validated analytical methods for isopyrazam are meager or lacking. In the present study, a single residual analytical method was developed for isopyrazam in selected commodities. Isopyrazam was analyzed in brown rice, soybean, green pepper, mandarin, cucumber, and Korean melon. We tried different solvents and methods through extraction, partition and purification steps to obtain best analytical results. For isopyrazam samples were extracted with acetonitrile, concentrated and partitioned with n-hexane, clean-up using florisil with n-hexane/ethylacetate (70/30) and analyzed with HPLC/UVD. The limit of quantitation (LOQ) for isopyrazam was 1.0 ng (S/N > 10) and method LOQ (MLOQ) was 0.04 mg $kg^{-1}$. Recovery ranged through 81.0~105.3% (syn-isomer) and 80.8~105.6% (anti-isomer) at fortification level of 0.04 (MLOQ), 0.4 (10 ${\times}$ MLOQ), and 2.0 (50 ${\times}$ MLOQ). The coefficient of variation (CV) for isopyrazam was less than 10% regardless of sample types. These results were further confirmed with LC/MS, respectively. The proposed method is highly reproducible and sensitive and is suitable for routine analysis.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.471-477
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• 2004

Exposure to elevated temperatures, chemical (active oxigen), or physical stress (UV light) induces immediate physiological response, the expression of heat shock proteins in cells. Thus, cells with elevated Heat Shock Protein levels become more tolerant to stress conditions that are otherwise lethal. First, we studied on the new function of glucuronic acid (GA) as preventive material of skin aging. The application of the GA shows significant induction of Heat Shock Protein 70 kDa (HSP 70 kDa) in contrast to cells without it. GA at the concentration which can induce HSP 70 kDa, protects the cell death induced by second stress (heat shock and hydrogen peroxide) in NIH3T3 cells. Second, we studied on in vitro transdermal permeation characteristic of GA through the excised mouse skin. In this study, we compared the skin permeability of GA in water with O/W emulsion. As a result, skin permeation parameters of GA shows lag time 1.2 h, partition coefficient 0.114, permeation flult rate $0.83114 mg/cm^2/h.$ In case of lag time, O/W emulsion containing GA increase 2.48 h. Also, the total accumulation permeation content decreased in contrast to GA solution after 24 h. But it has long-term permeability of glucuronic acid. These results suggest that glucuronic acid could be a good cosmetic active ingredient.