• The Korean Journal of Ecology
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• v.16 no.2
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• pp.191-198
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• 1993

The relationships between microbial activity and disturbance level of soil were investigated from 15 parks in Seoul and undisturbed area. The physico-chemical characteristics of soil and dehydrogenase activity(DHA) as an index of soil microbial activity were analysed. There were ranges of 3.84~7.37 in pH, 9.63~40.33% in moisture content, 3.41~21.49% in organic matter, 0.36~0.79g/g in water holding capacity and 0.03~0.53% in total nitrogen investigated sites. DHA values of soil were 8.64~$146.76{\mu}g/g$ in park soil and 545.14~$1, 198.80{\mu}g/g$ in undisurbed area. DHA of park soil with high traffic density and contamination source from human activities was much lower than that of undisturbed area. DHA was positively correlated with moisture content, organic matter, water holding capacity and total nitrogen.

• Nutrition Research and Practice
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• v.1 no.3
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• pp.189-194
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• 2007

This study investigated in vitro antioxidant activity of Sonchus oleraceus L. by extraction solvent, which were examined by reducing power, hydroxyl radical-scavenging activity(HRSA) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. 70% MeOH extract had the greatest reducing power while EtOH extract had the greatest HRSA. The antioxidant activity of S. oleraceus extracts was concentration dependent and its $IC_{50}$ values ranged from 47.1 to $210.5\;{\mu}g/ml$ and $IC_{50}$ of 70% MeOH, boiling water and 70% EtOH extracts were 47.1, 52.7 and $56.5\;{\mu}g/ml$, respectively. 70% MeOH extract of S. oleraceus contained the greatest amount of both phenolic and flavonoid contents. The extracts tested had greater nitrite scavenging effects at lower pH conditions. The cytotoxic activity showed that EtOH extract had the best activity against the growth of stomach cancer cell. These results suggest that S. oleraceus extract could be used as a potential source of natural antioxidants.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.2
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• pp.115-123
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• 1996

Methanolic aqueous extracts of 100 plants were screened for antioxidative activity using Fenton's reagen/ethyl linoeate system and free radical scavenging activity using DPPH free radical generating system. The results suggest that at least six plants including Eugenia caryophyllata, Alpinia offiicinarum, Rhus verniciflua, Curcuma longa, Rheum palmatvm and Evodia officinalis may be the potential sources of antioxidant, But only one plant, Cornus officinalis, may be the potential source of free radical scavenger from natural plants.

• The Korean Journal of Food And Nutrition
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• v.21 no.2
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• pp.157-164
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• 2008

This study examined the antioxidant activity of methanol and water extracts from Orostachys japonicus A. Berger according to harvest times, by measuring electron donating ability(EDA), reducing power, superoxide dismutase(SOD)-like activity, thiobarbituric acid reactive substances(TBARS) and antioxidant activity within a linoleic acid emulsion. EDA increased proportionally with the extract concentration and the methanol extract had slightly stronger effects than the water extract. And reducing power and SOD-like activity were highest in the methanol extract. Overall, based on the data, the methanol extract of O. japonicus A. Berger harvested during $August{\sim}October$ presented the highest level of antioxidative activity and may be a good candidate as a natural antioxidant source.

• Mycobiology
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• v.49 no.1
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• pp.89-94
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• 2021

Forty-three (n = 43) endophytic fungi with different morphologic characteristics were from a medicinal plant Sceletium tortuosum, were utilized to investigate their antifungal effectiveness against pathogenic fungi. All fungal isolates exhibited antifungal activity against one or more pathogens in the dual culture test whereas only 33 fungal culture filtrates (77%) showed decent antifungal effect. Fusaria and Aspergillus were the dominate genus that displayed significant antifungal activity. Isolates GG02, GG09, ND15, and ND17 showed the broadest spectrum of antifungal activity. Furthermore, culture filtrate of Fusarium sp. DR08 exhibited a broad range of antifungal activity against all the pathogens. The results suggest endophytic fungi isolated from medicinal plant might be a source of novel bioactive molecules. To the best our knowledge, this is the first report on endophytic fungi isolated from native kougoed exhibiting antifungal activity against plant fungal pathogens.

• Journal of Radiation Protection and Research
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• v.33 no.1
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• pp.21-26
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• 2008

When the calibration on Liquid Scintillation Counter using the Solid $^3H$ Standard Source of 200,000DPM is executed, the uncertainty due to activity and geometry difference, exists. Therefore, this paper intends to evaluate environmental samples comparatively accurately as decreasing this uncertainty existing in the process of calibration. For this, measurements on samples manufactured by $^3H$ Standard Source and sensitivity study were performed. Also, this paper verified calibration results using Radioactivity-Error-Analysis Method, and evaluated quantitatively the effect by geometry and activity difference based on verification result. According to the result of sensitivity study, in case of using the exposure time of 75 sec and Repeat method, the measuring accuracy and precision of about $1{\sim}3%$ were increased in comparison with the existing method. By analysis result, the effect by activity difference did not appear, and a plastic cell existing into Teflon vial made a role as reflector. The less the effect of plastic cells are decreased, the more activity is high, and the effect of those can be neglected at the activity of 200,000 DPM.

• Progress in Medical Physics
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• v.15 no.4
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• pp.192-196
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• 2004

The activity of Ir-192 sources for high dose rate (HDR) Brachytherapy in Korea were measured by using the well-type chamber and using the calibration Jig with the Farmer-type ionization chamber to compare the manufacturer certificated source strength which is supplied with each new Ir-192 source. The activity of two different source models used in six hospitals were measured. The range of measured activities to the manufacturer's suggested ones was -2.40% to +3.31% for the calibration Jig and -3.12% to 0.00% for the well-type chamber system. The source strength values given by the manufacturer for the 6 sources were within ${\pm}5%$ for the two different measuring equipment. Our results demonstrate that well-type chamber as wall as Farmer-type chamber system are appropriate system for the routine source calibration procedures in HDR brachytherapy. Whenever a new source is installed to use in clinics, a source calibration should be carried out.

• Proceedings of the Korean Nuclear Society Conference
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• 2003.05a
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• pp.303.2-303.2
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• 2003

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2019.05a
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• pp.195-196
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• 2019

• Journal of Microbiology and Biotechnology
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• v.21 no.1
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• pp.37-42
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• 2011

A new versatile acrylonitrile-bioconverting strain isolated from a petroleum-contaminated sludge sample and identified as Rhodococcus ruber AKSH-84 was used for optimization of medium and biotransformation conditions for nitrilase activity to produce acrylic acid. A simple and rapid HPLC protocol was optimized for quantification of acrylic acid, acrylamide, and acrylonitrile. The optimal medium conditions for nitrilase activity were pH of 7.0, temperature of $30^{\circ}C$, agitation of 150 rpm, and inoculum level of 2%. Glycerol as a carbon source and sodium nitrate as the nitrogen source provided good nutritional sources for achieving good biotransformation. Nitrilase activity was constitutive in nature and was in the exponential growth phase after 24 h of incubation under optimal conditions without addition of any inducer. The substrate preference was acrylonitrile and acetonitrile. The present work demonstrates the biotransformation of acrylonitrile to acrylic acid with the new strain, R. ruber AKSH-84, which can be used in green biosynthesis of acrylic acid for biotechnological processes. The nitrilase produced by the isolate was purified and characterized.