• Journal of Korean Society for Atmospheric Environment
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• v.23 no.4
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• pp.457-465
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• 2007

This study was performed to estimate the gas-particle partitioning of organochlorine pesticides (OCPs) in atmosphere, the samples were collected by PUF high volume air sampler for two years from June, 2000 to June, 2002. The gas phase fraction of ${\alpha/\gamma}-HCH$, heptachlor epoxide, ${\alpha/\gamma}-chlordane$ and trans-nonachlor was over 90%. But the gas phase fraction of ${\beta}-HCH$, p,p'-DDE, endosulfan sulfate, p,p'-DDD and p,p'-DDT was range of 20% through 80%, which means the gas phase fraction of OCPs components described above is sensitive to temperature. The correlation between the gas phase fraction and molecular weight of each OCPs component was not found in this research. The slope of regression line between gas-particle partitioning coefficient(${\log}K_p$) and subcooled liquid vapor(${\log}{P^o}_L$), gal-particle partitioning coefficient(${\log}K_p$) and octanol-air partitioning coefficient(${\log}K_{oa}$) which show -0.54 and 0.43 was not steep. So the equilibrium state between gas and particle was not reached and in this state the particulate fraction was low.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.73-81
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• 2010

The cemented sand and gravel (CSG) method is a construction technique that adds cement and water to rock-like materials, such as rivered gravel or excavation muck which can be obtained easily at areas adjacent to dam sites. This study was performed to evaluate the compaction and compressive strength properties of stress-strain, elastic modulus and fracture mode CSG materials reinforced polypropylene fiber. Polypropylene fiber widely used for concrete reinforcement is randomly distributed into cemented sand. The two types of polypropylene fiber (monofillament and fibrillated fiber) were used and fiber fraction ratio was 0, 0.2 %, 0.4 %, 0.6 % and 0.8 % by the weight of total dry soil. The effect of fiber fraction ratio and fiber shape on compaction and compressive strength were investigated. The optimum moisture contents (OMC) of CSG material increased as fiber fraction increased and the dry density of CSG material decreased as fiber fraction. Also, the maximum increase in compressive strength was obtained at 0.4 % content of monofillament and fibrillated fiber. CSG material behaviour was controlled not only by fiber fraction but also fiber distribution, fiber shape and fiber type.

• Korean Journal of Veterinary Research
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• v.34 no.2
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• pp.249-258
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• 1994

This study was carried out to investigate the inhibitory effects of vitamin E on the oxidative damage of cellular lipids and proteins in free radical reaction induced by $FeCl_3$, and ascorbic acid. In this experiment, a vitamin E treated rat group was administered with 100mg/kg body weight of $dl-{\alpha}-tocophery$ 1 acetate and an untreated rat group was administered with the same volume of corn oil. And then assays of malondialdehyde and carbonyl group in total homogenate, mitochondrial and microsomal fraction of rat liver were carried out at the scheduled time. The results obtained from this study were summarized as follows; 1. Lipid peroxidation levels in vitamin E administered rat liver cells were significantly (p<0.05) decreased at the intervals between 1 hour and 4 hours in liver homogenate, at all times except for 1 hour point in mitochondrial fraction, and also at the intervals between 0.5 hour and 3 hours in microsomal fraction compared with those of the control rat liver cell. 2. Protein oxidation levels in vitamin E administered rat liver cell were also significantly (p<0.05) decreased at the intervals between 1.5 hours and 4 hours in liver homogenate, at over 4 hours in liver mitochondrial fraction, and at the intervals between 0.5 hour and 3 hours in liver microsomal fraction compared with those of the control rat liver cells.

• Korean Journal of Pharmacognosy
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• v.41 no.3
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• pp.210-215
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• 2010

Acute toxicity on the polysaccharide fraction of Pueraria lobata was examined using male and female Sprague-Dawley rats. The polysaccharide fraction of Pueraria lobata was orally administered at a dose of 5 mg/kg, 50 mg/kg, 500 mg/kg, 2,000 mg/kg and 5,000 mg/kg and observed for two weeks. No mortality and abnormal clinical signs were observed at the doses used. There were not any significant differences in parameters of blood biochemical values and urinalysis by the treatment of test material. All rats were appeared to be healthy and normal throughout the observation period. Also there was no difference in net body weight gain and gross pathological findings among the groups rats treated with different doses of the polysaccharide fraction with Pueraria lobata.

• Korean journal of food and cookery science
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• v.13 no.1
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• pp.23-29
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• 1997

The hypoglycemic effect of fractions of methanol extract of Cassia tora was investigated in diabetic rats. Sprague-Dawley male rats weighing 180∼230 g were divided into 6 groups. Diabetes was induced in the male rats by intravenous injection of streptozotocin at a dose of 45 mg/kg dissolved in citrate buffer (pH 4.5). The diabetic animals then had plasma glucose concentration of above 300 mg/㎗. Fractions of methanol extract of Cassia tora were administered orally into the diabetic rats for 14 days after streptozotocin injection. The food intake and body weight gain were monitored and plasma levels of glucose, triglyceride, free fatty acid, HDL-cholesterol, cholesterol and ALT activity were determined. Levels of glycogen, cholesterol and triglyceride in liver were analysed. Weights of liver and kidney were lighter in all the fraction-administered groups than streptozotocin-control group. Plasma glucose level was significantly decreased by the administration of butanol fraction at 14 days. Plasma triglyceride levels were lower in chloroform, butanol and H$_2$O fraction-administered groups compared to streptozotocin-control group. Plasma cholesterol and HDL-cholesterol levels were not significantly different in all groups. Administrations of each of the four fractions have decreased plasma free fatty acid level, ALT activity and liver triglyceride levels in the diabetic rats. Liver glycogen levels in chloroform, butanol and H$_2$O fraction-administered groups were higher than streptozotocin-control group. It is suggested from the results that butanol fraction of methanol extract of Cassia tora may contain the antihyperglycemic compounds.

• Korea-Australia Rheology Journal
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• v.13 no.2
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• pp.83-87
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• 2001

The morphology and mechanical properties of the blends of a syndiotactic polystyrene (SPS) and poly-styrene-block-poly(ethylene-co-butylene)-block-polystyrene copolymers (SEBS) with various polystyrene block contents are studied. Mechanical properties, especially elongation at break and impact strength (IS), of the blend depend upon the morphology and interfacial adhesion, which in rum are affected by the viscosity ratio of constituent components and the styrene block content in SEBS. The IS of a blend was affected by the combined effect of rubber content and the interfacial adhesion. A maximum IS was found for a blend with the weight fraction of the PS block in an SEBS of 0.18. The IS of blends with smaller weight fractions of the PS block exhibited lower due to poor interfacial adhesion between SPS/SEBS in spite of a larger amount of rubber block. On the other hand, the IS of blends with larger weight fraction of the PS block becomes smaller due to lower amounts of rubber block in spite of better interfacial adhesion.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.769-779
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• 2020

This study investigates the selective fractionation of lignin with uniform structures and lower molecular weight. Lignin solubilization was first performed using a solution of acetic acid (AA) and hydrogen peroxide (HP) (4:1, (v/v)) to form peracetic acid (PAA), which is a strong oxidant. After the PAA-induced solubilization that occurred at 80℃, totally soluble lignin was extracted by ethyl acetate (EA) and divided into organic- and water-soluble fractions. The EA fraction was then fractionated by open-column using three solutions (chloroform-ethyl acetate, methanol, and water) sequentially. With an increase in the solvent polarity during the fractionation step, the molecular weight of the lignin-derived compounds in the fraction increased. Remarkably, some lignin fractions did not have aromatic structures. These fractions were identified as carboxylic acid-containing polymers like poly-carboxylates. These results conclude that the selective production of lignin-derived polymers with specific molecular weight and structural characteristics could be possible through open-column fractionation.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.37-46
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• 2007

The service life of agricultural concrete structures is designed in about 30 to 100 years, but actual service lift is estimated in an average 18 years. Therefore, as the service life of the agricultural concrete structures increases, necessity of repair by aging from various environment condition exposure increases. This study was to determinate the optimum mix proportion of latex modified repair mortar and to improve the durability performance of agricultural concrete structures. The physical and mechanical tests of latex modified repair mortar were performed. Tests of flow, compressive strength, flexural strength and bond strength tests were conducted. Test results show that the optimum nex proportion of latex modified repair mortar, when used in 5% latex volume fraction (weight of cement), 1.5% antifoaming agent (weight of latex), 0.2% PVA fiber volume fraction, 1:2 (binder-sand ratio), 10% silica fume replacement ratio (weight of cement), could result in best performance for the repair of agricultural concrete structures.

• The Journal of Korean Medicine
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• v.17 no.1 s.31
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• pp.132-145
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• 1996

Ethyl ether fractions of Ferula Resina(EFR) and Lithospermi Radix(ELR) and hexane fraction of Salviae miltiorrhizae Radix(HSR) exerted an inhibitory effect on cell adhesion of A549 to extracelluar matrix most effectively in vitro cell adhesion assay. Thus, with above fractions for the evaluation of antitumor activity, T／C% was monitored in ICR bearing S-180 and for antimetastatic effect, pulmonary colonization assay, weight of organs, changes of WBC and platelet were studied. In pulmonary colonization assay incidence rate to control was 73 % 42 %, 14 % in ELR, HSR and EFR-treated groups repsectively. Gain of lung weight was significantly inhibited in all groups while spleen weight was significantly reduced only in SMR group, but no changes in kidney and liver as compared with control. Number of platelet was significantly increased in all groups to normal range as compared with thrombocytopenic contol. WBC was significantly reduced only in LR group. These results suggest that ethyl ether fraction of Ferula Resina has more effective antimetastatic activity.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.1
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• pp.31-38
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• 2008

The primary objective of this study was to evaluate the variation of the molecular size distribution by granular activated carbon (GAC) adsorption. GAC adsorption was assessed by using the rapid small-scale column test (RSSCT) and high-performance size-exclusion chromatography (HPSEC) was used to analyze the molecular size distribution (MSD) in the effluent of GAC column. RSSCT study suggested that GAC adsorption exhibited excellent interrelationship between dissolved organic carbon (DOC) breakthrough and MSD as function of bed volumes passed. After GAC treatment, the nonadsorbable fraction which was about 25percents of influent DOC corresponded to the hydrophilic (HPI) natural organic carbon (NOM) of NOM fractions and was composed entirely of <300 molecular weight (MW) in the HPSEC at the initial stage of the RSSCT operation. The dominant MW fraction in the source water was 1,000~5,000daltons. At the bed volumes 2,500, MW <500 of GAC treated water was risen rather than it of source water. After the bed volumes 7,300 of operation, the MW 1,000~3,000 fraction was closed to about 80percents of DOC found in the GAC influent. The Number-average molecular weight (Mn) value determined using HPSEC for the effluent of GAC column was gently increased as DOC breakthrough progress. The quotient p(Mw/Mn) can be used to estimate the degree of polydispersity was shown greatest value for the GAC effluent at the initial stage of the RSSCT operation.