• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.71-84
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• 2003

The metallic shell of soil-steel structures are so weak in bending moment that it should sustain the applied load by the interaction of the backfill soil around the structures. The shell can be subjected to excessive bending moment during side backfilling or under live-load when the soil cover is less than the minimum value. The current design code specifies the allowable deformation and Duncan(1979) and McGrath et al.(2001) suggested the strength analysis methods to limit the moments by the plastic capacity of the shell. However, the allowable deformation is an empirically determined value and the strength analysis methods are based on the results of FE analysis, hence the experimental verification is necessary. In this study, the full-scale tests were conducted on the high-profile arch to investigate its behaviors during backfilling and under static live-loads. Based on the measurements, the allowable deformation of the tested structure could be estimated to be 1.45% of rise, which is smaller than the specified allowable deformation. The comparison between the measurements and the results of two strength analyses indicate that Duncan underestimates the earth-load moment and overestimates the live-load moment, while McGrath et al. predicts both values close to the actual values. However, as the predicted factors of safeties using two methods coincide with the actual factor of safety, it can be concluded that both methods can predict the structural stability under live-loads adequately when the cover is less than the minimum.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.110-122
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• 2012

This study examined the benthic diatom community distribution, land cover/use and water quality in relation to stream shape complexity (SSC) in the Seom River watershed. SSC showed a significant relation to the riparian land cover/use pattern and also water quality variables of the studied streams. Streams with high stream shape complexity (HSC) appeared to have a high proportion of forest and farmland, while streams having a low stream shape complexity (LSC) appeared to have high proportion of city. Streams with lower SSC showed higher nutrients concentration in the stream waters. Benthic diatom species composition and dominant species appeared to be similar regardless of SSC differences among the studied streams, while the variation of diatom density was manifested with SSC. The relative abundance of dominant benthic diatoms varied with SSC. Saprophilic diatoms were dominant in the streams of LSC, while saproxenic diatoms were dominant in the streams of HSC. During the evaluation of biological water quality using the benthic diatom indices, Trophic Diatom Index (TDI) and Diatom Assemblage Index to organic water pollution (DAIpo), the streams of LSC generally showed poorer water quality than those of MSC (Middle stream shape complexity) and HSC. In particular, BOD, TP, and $PO_4$-P showed significant relationships with DAIpo. In conclusion, shape complexity of streams in the Seom River watershed showed a close relation with benthic diatom distribution. This relation seemed to primarily be resulted from the effect of proximate factors, such as water quality, which might be affected by the land use types determining the degree of SSC.

• Restorative Dentistry and Endodontics
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• v.41 no.2
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• pp.91-97
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• 2016

Objectives: The purpose of this ex vivo study was to compare the antifungal activity of a synthetic peptide consisting of 15 amino acids at the C-terminus of human ${\beta}$-defensin 3 (HBD3-C15) with calcium hydroxide (CH) and Nystatin (Nys) against Candida albicans (C. albicans) biofilm. Materials and Methods: C. albicans were grown on cover glass bottom dishes or human dentin disks for 48 hr, and then treated with HBD3-C15 (0, 12.5, 25, 50, 100, 150, 200, and $300{\mu}g/mL$), CH ($100{\mu}g/mL$), and Nys ($20{\mu}g/mL$) for 7 days at $37^{\circ}C$. On cover glass, live and dead cells in the biomass were measured by the FilmTracer Biofilm viability assay, and observed by confocal laser scanning microscopy (CLSM). On dentin, normal, diminished and ruptured cells were observed by field-emission scanning electron microscopy (FE-SEM). The results were subjected to a two-tailed t-test, a one way analysis variance and a post hoc test at a significance level of p = 0.05. Results: C. albicans survival on dentin was inhibited by HBD3-C15 in a dose-dependent manner. There were fewer aggregations of C. albicans in the groups of Nys and HBD3-C15 (${\geq}100{\mu}g/mL$). CLSM showed C. albicans survival was reduced by HBD3-C15 in a dose dependent manner. Nys and HBD3-C15 (${\geq}100{\mu}g/mL$) showed significant fungicidal activity compared to CH group (p < 0.05). Conclusions: Synthetic HBD3-C15 peptide (${\geq}100{\mu}g/mL$) and Nys exhibited significantly higher antifungal activity than CH against C. albicans by inhibiting cell survival and biofilm.

• Journal of Environmental Science International
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• v.21 no.8
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• pp.977-988
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• 2012

This study analyzed the characteristics of stormwater runoff by rainfall type in orchard areas and transportation areas for 2 years(2010~2011year). Effluents were monitored to calculate the Event Mean Concentrations(EMCs) and runoff loads of each pollutant. The pollutant EMCs by volume of stormwater runoff showed the ranges of BOD 0.9~13.6 mg/L, COD 13.7~45.2 mg/L, SS 4.1~236.4 mg/L, T-N 2.123~21.111 mg/L, T-P 0.495~2.214 mg/L in the orchard areas, and was calculated as BOD 2.3~22.5mg/L, COD 4.4~91.1 mg/L, SS 4.3~138.3 mg/L, T-N 0.700~13.500 mg/L, T-P 0.082~1.345 mg/L in the transportation areas. The correlation coefficient of determination in the orchard area was investigated in the order of Total Rainfall(0.81) > Total Runoff(0.76) > Rainfall Intensity(0.56) > Rainfall Duration(0.46) > Antecedent Dry Days(0.27). Also, in the case of the transportation area was investigated in the order of Total Rainfall (0.55) > Total Runoff(0.54) > Rainfall Intensity(0.53) > Rainfall Duration(0.24) > Antecedent Dry Days(0.14). As the result, comparing valuables relating to runoff of non-pollutant source between orchard areas and transportation areas, orchard area($R^2{\geq}0.5$ : X3, X4, X5) was investigated to have more influence of diverse independent valuables compared to the transportation area($R^2{\geq}0.5$ : X3, X4) and the difference of discharge influence factor by the land characteristics appeared apparently.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.195-206
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• 2017

We described a spatial distribution pattern and floral diversity on the Paspalum distichum community occurring at the ecological parks of Hwamyeong, Daejeo, Samnak, and Maekdo in the Nakdong river estuary. A total distribution area of P. distichum community was $303,462.6m^2$. Its largest area was found in Samnak eco-park ($185,910.1m^2$). The most richness of knotgrass patches in each ecological park was determined Maekdo eco-park (87). Cover class level-5 shows the largest area ($260,663.2m^2$). A total of 73 taxa (34 families, 55 genus, 65 species, and 8 varieties) were listed up on the P. distichum community. A welldeveloped population of knotgrass was found predominantly at sites linked into human impacts at the riverine floodplain, the stream courses flowing through the parks, and the man-made channels and wetlands. Finally we proposed an ecological management strategy for knotgrass population in the study area.

• Korean Journal of Plant Resources
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• v.14 no.2
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• pp.108-115
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• 2001

For determining the effect of extracts exudated from ten industrial plant resources on germination and early growth of shoot and root of radish the allelopathic compounds screened. Germination rate and seedling growth of radish differed depending on plant species and extract concentration. Lower levels of 1% extracts exudated from industrial plant resources promoted the rate of germination of radish while higher levels of 10% extract inhibited the rate of germination. Germination rate, shoot growth and root growth of radish in higher concentration of extract also differed depending on the plant species exudated and extract concentraton of industrial plant resources. Higher concentration of extracts from Xanthium strutnarium L. Angellica gigas Nakai, and Solanum nigrum L. were completely inhibited the germination while those from Cichorium intybus L., and Polygonatum officinale Allioni were not inhibited. Extracts exudated from Xanthium strutnarium L, Angellica gigas Nakai, and Solanum nigrum L. showed the strong inhibition of shoot and root growth of radish while those from Cichorium intybus L., and Polygonatum officinale Allioni did not show the bioactivity in shoot and root growth of radish..

• Research in Community and Public Health Nursing
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• v.10 no.1
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• pp.227-238
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• 1999

The goal of this study is to discover the effect of sex education on sex-related knowledge and attitudes of middle school girls. Non-equivalent control group pretest-posttest design was used. The number of experimental group students was 134 and the number of control group students was 134. A total of 268 second grade middle school girls were selected for a convenience sampling method. This study was carried out in a middle school located in Taegu City, Korea, from February 5 to February 18, 1998. To des cover the needs of sex education, the researcher sent a predesigned questionnaire to 1464 girls in 19 different middle schools. The sex education curriculum was designed on the basis of this survey's results. 'The Sex Education Teaching Plan' (published by the Research Institution of Korean School Health Education) and 'Sex and Happiness' (published by the Seoul City Education Ministry) were used to redesign the sex education curriculum and content. Fifty minute long sex education classes were taught to the experimental group every other day and the total number of classes was five. The contents of the teaching -learning plan for sex education were: 'The Characteristics of Adolescence', 'Pregnancy and Contraception', 'Friendship with the Opposite Sex and Prevention of Sexual Violence', 'Prevention of Venereal Disease', and 'Sex and Society'. To measure the degree of sex knowledge of the subjects, the researcher used the modified sex knowledge tools of Kim(l995) and Han(1997). The reliability values of these sex knowledge tools range from 0.71 to 0.74, using Cronbach's alpha. To measure the degree of sex attitude in the subjects, the researcher used the modified sex attitudes tools of Han(l997). The reliability values of these sex attitude tools range from 0.73 to 0.78 using Cronbach's alpha. The PC-SAS package program was used to analyse the data along with Frequency, Percentage, XLtest, t -test, and a paired t -test The results of this study were as follows; 1. The first hypothesis was accepted. The experimental group showed more change in sex - related knowledge than the control group(t =22. 76, p=0.0001). 2. The second hypothesis was accepted. The experimental group showed more change in sex-related attitudes than the control group (t=11.91, p=0.0001). In conclusion, the level of sex-related knowledge and sex-related attitudes of middle school girls who received sex education was higher than that of the girls who did not receive sex education. According to this research, planned sex education was effective in forming accurate knowlege and appropriate attitudes related to sex. Clearly, we must carry out a well-designed step by step sex education program that is well-suited to the sex education needs and the developmental level of the students.

• Journal of The Korean Society of Grassland and Forage Science
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• v.22 no.4
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• pp.233-240
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• 2002

Hairy vetch(Vicia villosa Roth) which is legume fur winter cover crop can supply nitrogen for companion crop and soil. The purpose of this study was to improve the forage quality and productivity using forage crop and hairy vetch in winter season fer three years. The results of this experiments were summarized as follows. Plant height of rye was decreased but hairy vetch was increased. The heading stage of rye did not show difference among the treatments. The content of dry mater(DM) was decreased with increased ratio of hairy vetch/rye but it did not show significant difference between seeding methods. Crude protein(CP) content tended to increase in mixture plots. Acid detergent fiber(ADF) and NDF(neutral detergent fiber) content of mixture plots were lower than that of rye mono-cultivated. In vitro dry matter digestibility(IVDMD) and TDN(total digestible nutrient) content were showed inverted tendency. The highest DM yield was in rye mono-cultivated, but it was similar between mono-cultivated and mixture I (P<0.05). In the CP yield, it did not show the significant difference between rye mono-culture and mixture I . The content of total nitrogen in soil showed slight increase as 0.06∼0.08%. Conclusively, mixture I showed equal or superior productivity and quality comparing with rye mono-cultivated, mixture I would be recommended to produce higher yield and to conserve soil environment.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.189-200
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• 2005

Biological nitrogen fixation is an important process for academic and industrial aspects. This review will briefly compare industrial and biological nitrogen fixation and cover the characteristics of biological nitrogen fixation studied in Azotobacter vinelandii. Various organisms can carry out biological nitrogen fixation and recently the researches on the reaction mechanism were concentrated on the free-living microorganism, A. vinelandii. Nitrogen fixation, which transforms atmospheric $N_2$ into ammonia, is chemically a reduction reaction requiring electron donation. Nitrogenase, the biological nitrgen fixer, accepts electrons from biological electron donors, and transfers them to the active site, FeMo-cofactor, through $Fe_4S_4$ cluster in Fe protein and P-cluster in MoFe protein. The electron transport and the proton transport are very important processes in the nitrogenase catalysis to understand its reaction mechanism, and the interactions between FeMo-cofactor and nitrogen molecule are at the center of biological nitrogen fixation mechanism. Spectroscopic studies including protein X-ray crystallography, EPR and $M{\ddot{o}}ssbauer$, biochemical approaches including substrate and inhibitor interactions as well as site-directed mutation study, and chemical approach to synthesize the FeMo-cofactor model compounds were used for biological nitrogen fixation study. Recent research results from these area were presented, and finally, a new nitrogenase reaction mechanism will be proposed based on the various research results.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.665-675
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• 2010

The effects of chemical binders (ladle slag, ordinary portland cement (OPC), hydroxyapatite and calcium hydroxide) on the solidification/stabilization of heavy metals (Cd, Cu, Ni, Pb, Zn) in sewage sludge were evaluated by chemical leaching tests such as EDTA extraction, TCLP and sequential extraction. The results of EDTA extraction showed that heavy metal concentrations in sewage sludge were highly reduced after solidification/stabilization with slag, cement or calcium hydroxide. However, EDTA interrupted solidification/stabilization of heavy metals by hydroxyapatite. The TCLP-extracted heavy metal concentrations in sewage sludge after solidification/stabilization with chemical amendments were highly reduced. However, Cu concentration in the sewage sludge solidified/stabilized with slag, cement or calcium hydroxide increased because the pH of TCLP solution was higher than 7. Mixtures of sludge 1 : slag 0.2 : calcium hydroxide 0.1 (wt ratio) showed the least leachability in batch TCLP and EDTA extraction. The results of sequential extraction (SM&T, formaly BCR) indicated that the distribution of heavy metals changed from exchangable and carbonate fractions to strongly bound organic fraction. It was found that maximum leachate concentrations of Ba, Cd, Cr and Pb from sewage sludge amended with slag and calcium hydroxide were far below US EPA TCLP regulations.