• Journal of Powder Materials
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• v.17 no.3
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• pp.190-196
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• 2010

In this paper, rapid solidified Mg-4.3Zn-0.7Y (at.%) alloy powders were prepared using an inert gas atomizer, followed by a severe plastic deformation technique of high pressure torsion (HPT) for consolidation of the powders. The gas atomized powders were almost spherical in shape, and grain size was as fine as less than $5\;{\mu}m$ due to rapid solidification. Plastic deformation responses during HPT were simulated using the finite element method, which shows in good agreement with the analytical solutions of a strain expression in torsion. Varying the HPT processing temperature from ambient to 473 K, the behavior of powder consolidation, matrix microstructural evolution and mechanical properties of the compacts was investigated. The gas atomized powders were deformed plastically as well as fully densified, resulting in effective grain size refinements and enhanced microhardness values.

• Journal of Wetlands Research
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• v.11 no.1
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• pp.91-97
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• 2009

The fowls manure is using as fertilizers for farmland because of enough nutrients. However, excess nutrients can be washed off during a storm and affected on nearby waterbodies. In this paper, the runoff characteristics from farmland were studied to determine the washoff mass. A lab-scale reactor was designed to estimate the surface runoff and infiltration rates according to the rainfall intensity. Surface runoff water did not occur at 10mm/hr rainfall intensity, but some runoff occurred at 20mm/hr rainfall intensity. At 32.4mm/hr rainfall intensity, it shows the highest pollutant concentrations such as 686mg/L for $BOD_5$ and at 630mg/L $COD_{Mn}$. The pollutant as based on fowls manure compost was highly washed-off by subsurface water at 32.4mm/hr rainfall intensity, however the concentration was largely decreased at 43.2mm/hr rainfall intensity. The summary of the results is that the highest wash-off concentrations value shows at 32.4mm/hr rainfall intensity for $BOD_5$ and at 67.1mm/hr for T-N and T-P.

• Membrane Journal
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• v.19 no.4
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• pp.333-340
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• 2009

This paper is designed with the purpose of improving the efficiency of the sulfonic acid ion exchange membranes by radiation induced graft polymerization. It has been shown that the porous hollow fiber membranes could cause permeability blocking between pores and ion exchanged graft chains. Addition of crosslinker such as N-ethylene glycol dimethacrylate will permit to increase the permeation flux. In this research, the ethylene glycol dimethacrylate (EDMA) and diethylene glycol dimethacrylate (DDMA) with different length are used as crosslinkers. The ion exchanged cross-linked membrane (EDMA, DDMA) containing sulfonic acid group by radiation induced grafted polymerization are sn died for adsorb metal ions (Pb). It has been shown that adsorbed metal ions ($Pb^{2+}$) for the EDMA and DDMA membranes with the density of sulfonic acid groups, 1.40 mmol/g and 2.14 mmol/g, respectively are 13.82 mg/g, 17.37 mg/g, accordingly.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.9-16
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• 2017

In this paper, sub-microwave oscillator sensor is proposed to non-invasively monitor the glucose concentration level of the human biological tissue by oscillation frequency variation. Inductive slot in the ground plane of the microstrip line is combined with the biological tissue, to realize the resonator as a part of the oscillator sensor. The phantom box mimicking the human tissue is introduced for simulation of the resonator which resonance frequency correspondingly shifts up on three step glucose concentration levels(0, 400, 800 mg/dL). Oscillator sensor circuit is fabricated as a prototype. Pig tissues instead of human is used. Oscillation frequency shift of about 14 MHz per glucose level of 400 mg/dL has been successfully measured around 1,100 MHz. This proves that the proposed sensor is applicable to a blood glucose sensor.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.632-637
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• 1999

The purposes of this study is to investigate the effect of Rhus chinensis gall extract on liver function, plasma lipid composition and antioxidant system in the obese rats with high fat diet for seven weeks. Thirty two male rats of Sprague Dawely strain were divided into four groups. they are normal group (basal diet), control group(high fat diet), III group(high fat diet with Rhus chinensis gall extract 25mg/kg body weight per day) and IV group(high fat diet with Rhus chinensis gall extract 250mg/kg body weight per day). Rats in III group and IV group were administered with Rhus chinensis gall extract accordingly. Weight gains showed a tendency to decrease in rat with Rhus chinensis gall extract group but showed no differences among treatment groups. Food intake and Food efficiency ratio were not significantly different among treatment groups. Plasma total cholesterol showed a tendency to decrease in Rhus chinensis gall extract group. HDL cholesterol showed a tendency to decrease in 25mg/kg of Rhus chinensis gall extract group. However, in the 250mg/kg of Rhus chinensis gall extract group, these values showed no significant difference compared to the control group (p<0.05). GPT activities showed no significant difference among treatment groups. GOT activities showed a tendency to decrease in the groups of Rhus chinensis gall extract groups. Lipid peroxide level was significantly higher in control group than those of normal group. In Rhus chinensis gall extract groups, lipid peroxide level showed a tendency to decrease, but glutathione peroxidase activity was progressively increased. Results of our research in this paper show that Rhus chinensis gall extract might improve liver function, antioxidant system and plasma lipid composition in rats with high fat diet.

• Journal of Ginseng Research
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• v.18 no.1
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• pp.32-38
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• 1994

Male rats aged 15 months, which had been over-trained with 12 arm radial maze up to the criterion of 1 or 2 errors an average per trial, were divided into two groups and 7 months after the over-training and were studied the effect of red ginseng trial saponin fraction (PT) on the spatial memory function. The rats which could be improved the performance of 9.75$\pm$1.26 (within 185$\pm$8.2 1 sec) were classified into "normal group" (n=4) and the ones, which showed R-maze performance of 7.0$\pm$2.87 within 300 sec, "deteriorated memory group" (n=5). PT was dissolved in distilled water and injected into the deteriorated memory group intraperitoneally at 30 min before R-maze for 3 consecutive days. The injected amount of PT on the 1st day was 10mg/rat, 1mg/rat both on the 2nd the 3rd day. As results, the performance was restored to 9.4$\pm$2.0 after stopping ginseng administration, although the lower performance values (1.4$\pm$0.89, 2.8$\pm$0.83, 3.8$\pm$0.84, respectively) were exerted during the three days of PT administration than before PT administration (7.0$\pm$2.87) since 1 day after administratitan of PT. The restored performance values were continuously maintained up to the level of the "normal group". However, any lower performance values were not observed when PT was administered via intraperitoneal route to the normal group in about of 2 mg/rat except 10mg1ra1. The number of errors when the foods in arms were put at only 6 places was clearly reduced during the 9 days of consecutive administration of PT as compared with untreated control. These results indicated that PT administration may enhance their cognitive function after a long lapse of time not only in the memory deteriorated rats but also in normal ones. The reason exerted lower performance values during PT administration in this paper was discussed as compared with the results of T-maze behavior of another 3-month-aged rats. of another 3-month-aged rats.

• YAKHAK HOEJI
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• v.4 no.1
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• pp.8-11
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• 1959

The method for the estimation of trace elements in hair is studied on this paper modifying the circular paper chromatography method shown by Giri and Balakrishnan for the estimation of vitamins from the multivitamin preparation. The elements studied are Ni, Al, Mn, Mg, Zn, Ca, Co, Cu, and Fe. The content of the element is estimated quantitatively by comparison the size and the color density of spots of the standard chromatogram prepared by the known amount of each standard substance and the chromatogram prepared from sample solution, after checking those chromatogram qualitatively. The comparative study has been made between the results from this method and the results from the other methods which are applying routinely at this laboratories. The experimental errors at each elements were within 10% limits. There was no interference between each elements. It is recommendable that this method can be applied to treat numerous speciemens saving times within experimental error of 10%.

• Journal of Life Science
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• v.32 no.8
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• pp.633-640
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• 2022

Recently, kenaf (Hibiscus cannabinus L.) has been highlighted due to its rapid growth in dry, infertile land and its versatile applications in textiles, paper, feed, food, medicine, and phyto-remediation. In Korea, a new cultivar, 'Jangdae', which has the merit of feasible seed-gathering, was established in 2013. However, most of the kenaf seeds used are still imported, and a comparison study of useful bio-activities between Jangdae and imported seeds has not been conducted. In this study, anti-thrombosis, antioxidant and anti-diabetic activities of the ethanol extracts of the Jangdae seed (E-JS) and 8 imported cultivar seeds (E-ICS) were investigated. The E-JS has 14.4 mg/g of total polyphenol and 5.3 mg/g of total flavonoids, whereas the E-ICS has 5.9~8.7 mg/g and 0.7~1.5 mg/g, respectively. Among the 9 kenaf seed extracts, IT 181215 and IT 207877 seed extracts showed 1.92 and 1.88-folds extended thrombin time (TT), and IT 207886 seed extracts showed 3.04-folds extended activated partial thromboplastin time (aPTT). All extracts, except Hong-ma seed, showed 1.36~1.56-folds extended prothrombin time (PT). The E-JS showed strong anti-thrombosis activities with 1.46-folds (TT), 1.38-folds (PT) and 2.37-folds (aPTT) compared to those of solvent controls. The E-JS has the strongest antioxidant activities among the seed extracts, with 0.48 mg/ml of RC₅₀ for ABTS cation and 0.27 mg/ml of RC₅₀ for nitrite scavenging. Meanwhile, the E-JS and IT 181215 extracts showed strong inhibition against α-glucosidase with 10.3~10.6% inhibition at 0.5 mg/ml. Our results suggest the E-JS has potential as an anti-thrombosis, antioxidant and anti-diabetic agent.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.3
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• pp.198-205
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• 2014

The present paper investigates the leaching property of coal fly ash (FA) using distilled water as solvent and its performance of mineral carbonation. The highest leaching efficiency is obtained at 100 min after leaching begins and the overall leaching efficiencies of Ca and Na via five consecutive leachings were calculated to be 25.37% and 7.40%, respectively. In addition, because $Ca(OH)_2$ produced during the leaching reacts with $SiO_2$ which is the major component of FA, the Pozzolanic reaction may occur and thus reduces leaching efficiency. Total carbonation capacity of FA by absorbing $CO_2$ into FA leachates is 6.08 mg $CO_2/g$ FA and the contribution of alkali substances such as Ca, Na, Mg and K to this value is calculated to be 5.19 mg $CO_2/g$ FA. Carbonation efficiencies of Ca and Na based on leachates are 85.62% and 77.70%, respectively. On the other hand, the ratios of Ca and Na in raw FA to participate in carbonation are calculated to be 9.04% and 5.26%, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.662-671
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• 2020

Recently, for the purposes of reducing carbon dioxide(CO₂) emissions in the island area, countermeasures to decrease the operation rate of diesel generator(DG) and to increase one of renewable energy sources(RES) is being studied. In particular, the demonstration and installation of stand-alone micro-grid(MG) system which is composed of DG, RES and energy storage system(ESS) has been implemented in some island areas such as Gapa-do, Gasa-do and Ulleung-do island. However, many power quality(PQ) problems may be occurred due to an intermittent output of RES including photovoltaic(PV) system and wind power(WP) system in a normal operating of constant voltage & constant frequency(CVCF) inverter-based MG system. Therefore, this paper presents a modeling of the 30kW scale MG system using PSCAD/EMTDC, and also implements a 30kW scale CVCF inverter-based MG system as test devices to analyze normal operating characteristics of MG system. From the simulation and test results, it is confirmed that the proposed methods are useful and practical tools to improve PQ problems such as under-voltage, over-voltage and unbalanced load in CVCF inverter-based MG system.