• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.13-18
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• 1999

Recently among after-treatment devices which have high possibility of utility diesel oxidation catalyst(DOC) is concerned over the world. DOC oxidizes pollutants by means of activate-reaction during by-passing in the catalyst in doing so conversion efficiency of PM, CO and HC is high and this device does not have an effect on engine performance because back pressure is not nearly increased, But as a small amount of sulfur content in fuel is oxidized it makes sulfate which is absorbed on the surface of catalyst. So in this study the experiment is carried out by means of using ordinary fuel(0.1wt%) and low sulfur fuel(0.05wt%) with DOC and the emission gas of diesel engine is measured.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.381-388
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• 1999

Several large scale reclamation projects are being underway along the coastal line in Korea. Therefore the large quantity of economical backfill material is necessary to cope with the shortage of dredged soil. In this study, the amount of volume reduction of dredged soil from detention basin was evaluated based on the laboratory tests. The percentage of soil particles in dredged organic soil is about 12.5∼21.9% by weight. The content of heavy metal and environmental effect for dredged soil itself and solidified dredged soil were analysed and the results are far below than those of environmental requirement.

• The Korean Journal of Ecology
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• v.17 no.2
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• pp.143-148
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• 1994

The relationships between microbial activity and physico-KDICical characteristics of soils were investigated in three golf courses of Kwanak, Gold and Korea Country Clubs, with different open years. The soil samples were collected in tee, fairway and rough. There were ranges of 4.80-5.55 in pH, $25.55-98.50{\mu}S$ / cm in conductivity, 10.96-16.73% in moisture content, 0.18-0.36g / g in water holding capacity, 3.68-5.39% in organic matter, and 0.10-0.25% in total nitrogen. Dehydrogenase activity(DHA) as an index of soil microbial activity was determined. DHA values of soil were $69.83-314.43{\mu}$g / g in three courses and showed the order of Kwanak>Gold>Korea Country Club with open year. This indicates that DHA was affected by several fertilizer treatments rather than herbicide and pesticide treatments. DHA was significantly different with golf clubs as well as golf courses and positively correlated with water holding capacity and total nitrogen.

• The Korean Journal of Ecology
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• v.19 no.1
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• pp.47-53
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• 1996

Effects of group breeding of herons on pine community were studied at Pomaeri, in Yangyang, Kangwon Province, Korea. This site has been protected as a Natural Monument (No. 229) since 1970. Herons have used this habitat as a breeding site from] anuary to October every year. In 1995, more than 500 herons were observed in this habitat. Many big pine trees are dying or already dead due to group inhabitation of herons, and no pine saplings were found at forest floor in this habitat. Nutrient contents of soil in this habitat were much higher than those in control plot. This must be due to the addition of feces from herons and of thin twigs and other organic materials from the canopy and bird nests. Species composition of herb layer in this habitat was quite different from that in control plot. Breeding site was dominated by Humulus japonicus. Persiearia perJohata, Persicaria thunbergii. and Commelina communis. which are indicator species of soil eutrophication.

• The Korean Journal of Ecology
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• v.8 no.1
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• pp.7-14
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• 1985

Biomass, carbon, nitrogen and phosphorus standing crops of bethic community were estimated at the trophic levels in the intertidal zone of Kum river estuary. Annual mean biomass of zoobenthos was 130.5g/$m^2$, body fraction 26.7g/$m^2$ and shell fraction 103.8 g/$m^3$. Biomass estimated as ash-free dry weight was total 28.9g/$m^2$, body fraction 20.2g/$m^2$ and shell fraction 8.7g/$m^2$ Carbon standing crops of zoobenthos were 15.9gC/$m^2$, in which organic carbon content was 7.0gC/$m^2$ and carbonate carbon was 8.9gC/$m^2$. Production efficiency by carbon standing crops from sediment to herbivores and carnivores and 10.6% and 16.0% in phosphorus, respectively. Annual primary production of benthic algae was crudely estimated to 329g.dw/$m^2$/yr by using the biomass and turn-over rate of benthic algae.

• Environmental Engineering Research
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• v.13 no.2
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• pp.73-78
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• 2008

For a given soil-contaminated site, a level of soil contamination is characterized and decisions on risk may be made from the risk assessment. The study evaluated critical design factors for the determination of sample size in the sampling design plan and the assessment of soil contaminant- leaching to groundwater. Two variables, the minimum relative detectable difference (T) and coefficient of variation (CV) were evaluated for the sample size determination. The minimum number of samples can be appropriately determined by CV under a T value greater than or equal to 0.2. Soil-contaminant leaching to groundwater was evaluated by using the Soil Screening Level equation of U.S. Environmental Protection Agency and the Risk Based Screening Level equation of American Society for Testing and Materials, with the same input parameters. The groundwater concentrations estimated from soil contaminant concentrations were significantly affected by the Darcy velocity of groundwater and the organic content of soil.

• Journal of Environmental Health Sciences
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• v.15 no.2
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• pp.33-40
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• 1989

Dichromate reflux method for COD analysis is one of the useful and precise way to solve the organic content of the wastewater. But the standard procedure for COD is not entirely satisfactory for sample containing appreciable amounts of inhibiting substance, especially chloride ion. Under the conditions of the established test, a big disadvantage of the method is that dichromate oxidizes chloride quantitatively to chlorine. When it is necessary to use silver sulfate as a catalyst in the COD procedure, chloride must be removed before the addition of the catalyst. Silver sulfate and mecuric sulfate forms a precipitate of AgCl and HgCl$_{2}$ separately which is not completely oxidized during the test and, therefore, cannot be corrected for. So, we evaluate and compensate the amount of chloride oxidation in the absence of chemicals during the experimental procedure. Calculation of COD is made using the following reviced formula: real COD = tested COD - 0.2277Cl.

• Microbiology and Biotechnology Letters
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• v.24 no.3
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• pp.364-370
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• 1996

Sediments collected from the Jungnang-cheon and its tributaries were used to enumerate anaerobic bacteria by most probable number (MPN) methods. A simple method was developed to detect ferrous ion in the culture fluid in order to count the number of iron ion reducers, and sulfate-reducing bacteria (SRB) and methanogens were detected by the presence of FeS precipitate in the culture or methane in the head space, respectively. The numbers of iron reducer was in the range of 10$^{7}$ - 10$^{8}$ /g in the sediment of the stream containing higher organic content than the tributaries. The sediments of tributaries were analyzed to contain iron reducers less than 10$^{7}$ cells/g. With one exception the numbers of SRB and methanogens were less than 10$^{3}$ cells/g in the sediment. From these results it is concluded that organics in the sediment support the growth of iron reducers, which out-compete SRB and methanogens.

• Journal of Food Hygiene and Safety
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• v.10 no.1
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• pp.33-39
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• 1995

The antibacterial and antifungal effect of grapefruit seed extract(GFSE) was investigated for its purpose of application to a diverse spectrum of field as sanitizers, disinfectants and preservatives. GFSE showed coparatively high content of such flavoniods as naringin and hesperidin and ascorbic acid. GFSE containing a low level of organic acids is a heavy viscous and water-soluble liquid. As a result of the antimicrobial test of GFSE, Bacillus subtilis and Aspergillus oryzae did not survive at detectable levels when treated with more than 100 ppm of GFSE. The minimum inhibitory concentrations of GFSE for a wide variety of pathogenic and putrefactive bacteria, fungi and yeasts were 100 ppm and 250 ppm, respectively. In the comparable electron micrograph of microbial cells treated with GFSE or not, we could conclude that GFSE destroy microorganisms by disrupting the functions of the cell wall membrane and microbial spores.

• Food Science and Preservation
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• v.6 no.1
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• pp.61-65
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• 1999

This study was carried out to investigate change in the components according to drying methods of jujube. Raw jujube was dried with five methods such as sun-drying, hot-air drying after pretreated with sunlight, blanching, microwave treatment, respectively. The contents of soluble sugar and protein in sun-dried jujube were higher than those of other drying methods. The free sugars of dried jujube were consisted of sucrose, glucose and fructose. And the contents of free sugar was not different by drying methods. The major organic acids of dried jujube were oxalic acid, citric acid and malic acid. The contents of glutamic acid, glycine and alanine were higher than those of other amino acids, and the content of each amino acid was not different by drying methods.