• Food Science and Biotechnology
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• v.15 no.1
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• pp.24-27
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• 2006

A simple HPLC quantification method was developed for genistein, genistin, daidzein, and daidzin in soybeans and soybean products. The procedure used a $4.6{\times}100\;mm$ $Chromolith^{(R)}$ RP-18e column with a mobile phase of 1% HOAc in 20% MeOH to 1% HOAc in 80% MeOH for 10 min. The injection volume was $2\;{\mu}L$ at a flow rate of 2 mL/min. Detection was carried out under UV at 254 nm. Under these conditions, the major isoflavones daidzein, daidzin, genistein, and genistin in soybean and soybean pastes were eluted within 7 min with baseline separation. Optimal extraction of the above four major isoflavones was achieved when 40 g of soybean or soybean paste was refluxed in 100 mL of 95% ethanol for 2 hr. Ten different soybean cultivars and nine commercial soybean pastes were analyzed by this method. The total isoflavone content was highest in the cultivar Somyung ($2,497\;{\mu}g/g$ dry weight). The isoflavone content in soybean pastes varied widely from manufacturer to manufacturer (an almost five-fold difference between the highest and lowest values). Such variations were presumably due to differences in fermentation conditions, type of soybeans used, and levels of such additives as starch and salt.

• Korean Journal of Medicinal Crop Science
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• v.20 no.2
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• pp.136-139
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• 2012

This study is part of research to develop the technology for managing major medicinal crops after harvest. We studied the optimal germination conditions of $Cynanchum$ $wilfordii$ (Maxim.) Hemsl. The mean germination time (MGT) of $C.$ $wilfordii$ seeds was higher after soaking for 4 days after storage at $5^{\circ}C$ for 8 weeks, than with germination at $25^{\circ}C$ (3 days). However, the germinative energy (GE) decreased as the number of days soaking increased. The greatest germination rate ($83.3{\pm}8.8%$) was at $25^{\circ}C$ with no soaking of seeds stored at $-20^{\circ}C$ for 8 weeks. Based on these results, we characterized the germination conditions of a major medicinal crop.

• Korean Journal of Medicinal Crop Science
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• v.20 no.2
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• pp.85-88
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• 2012

This study evaluated the germination rate of $Rheum$ $palmatum$ L. in Korea as affected by storage temperature, germination temperature, and a soaking treatment. The germination rate of $R.$ $palmatum$ L. stored at various conditions for 8 weeks was > 60%. The highest germination rate occurred at $25^{\circ}C$. The germination point of $R.$ $palmatum$ L. with soaking was started 1 day after application, and non soaked seeds germinated in 2 days. When $R.$ $palmatum$ L. was soaked with water, the germination rate was lower, but mean germination velocity was the highest. These results may help our understanding of variations in germination characteristics for seeds treated under different germination conditions.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.855-862
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• 2013

Although antioxidant activities of Korean traditional fermented foods were reported by many researchers, study on antioxidant activity of microorganism originated from Korean traditional fermented foods was little. Therefore, we improved condition for antioxidant production by a bacterium isolated from home-made Chungkookjang. We selected a bacterial strain, which showed the highest antioxidative activity, from Chungkookjang and then named GJ. The selected GJ strain was identified as Bacillus methylotrophicus by alignment data of 16S rRNA gene nucleotide sequences. Improved medium compositions for DPPH radical scavenging activity were 0.25% sucrose, 1% peptone, 0.01% $MgSO_4{\cdot}7H_2O$ and initial pH 6.5, respectively. Optimal culture conditions were $30^{\circ}C$, 200 rpm and 4% inoculum volume, respectively. In improved conditions, DPPH radical scavenging activity of GJ reached to 91% in a short time. The strain GJ also possessed ACE inhibition and other antioxidative activities; ACE inhibition activity (49.4%), ABTS radical scavenging activity (99.8%), metal chelating activity (67.9%), SOD-like activity (36.5%) and reducing power ($A_{700}$ = 5.982) were observed, respectively. Therefore, our results suggest that B. methylotrophicus GJ strain may be potential candidate for functional foods, cosmetic products for anti-aging and medicine for diseases caused by oxidative stress.

• Korean Journal of Environmental Agriculture
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• v.42 no.3
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• pp.193-202
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• 2023

Residue monitoring of propiconazole (PCZ) in cabbage, shallot, and spinach was conducted under multi-trial greenhouse conditions. This study aimed to understand the fate of the applied fungicide in these vegetables. Furthermore, the associated health risk of PCZ in leafy vegetables was assessed through dietary risk assessment. Commercially available PCZ (22% suspension concentrate) was administered thrice according to the OECD fungicide application interval guideline. The plant samples were extracted using a slightly modified QuEChERS technique and analyzed using gas chromatography-tandem mass spectrometry. The average PCZ recovery was between 84.5% and 117.6%, with a <5% coefficient of variance. The dissipation of PCZ residue in cabbage, shallot, and spinach after 14 days was 96%, 90%, and 99%, respectively, with half-lives of <5 days. Meanwhile, dietary risk assessments of PCZ residues in the studied vegetables using the risk quotient (RQ) were significant < 100 (RQ < 100). Thus, the population groups considered in this study were not at substantial risk from consuming leafy vegetables sprayed with PCZ following critical, good agricultural practices.

• Korean Journal of Child Studies
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• v.30 no.1
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• pp.11-25
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• 2009

This study aimed to investigate protective factors and risk factors in elementary students' life satisfaction. Participants were 2844 (1524 boys, 1320 girls) children who grades were 4th, 5th, 6th in KYPS (Korea Youth Panel Survey). Data mining decision tree model was performed with sex, appearance, delinquency, family income, attachment to parents, parental monitoring, attachment to teachers, academic achievement, peer delinquency, and attachments to peer. The results revealed that : (1) For 4th graders, academic achievement, attachment to parents, and appearance were significant predictors for life satisfaction. (2) For 5th graders, attachment to parents, academic achievement, parental monitoring and appearance were significant predictors for life satisfaction. (3) For 6th graders, attachment to parents, appearance, parental monitoring and delinquency were significant predictors for life satisfaction. Protective factors and risk factors were changed according to interactions between significant independent variables. These results suggest that children's diverse conditions should be considered individually in programs for children's life satisfaction.

• Journal of Applied Reliability
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• v.12 no.3
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• pp.187-199
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• 2012

In general, accelerated life testing is performed to reduce testing time. But it is difficult to apply accelerated life testing to a system besides components. This paper developed a software which estimates reliability measures of the system from results of accelerated life testing of components building the system. This software can handle the system with a large number of components and complex topology. Multiple failure modes of a component were also considered in this software. Based on the software, reliability measures of a gearbox example at several conditions were estimated from the accelerated life testing results of three components of the gearbox.

• Communications for Statistical Applications and Methods
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• v.6 no.2
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• pp.423-432
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• 1999

Accelerated life testing of product is commonly used to reduced test time and costs. In this papers is considered when the product is a two component system with lifetimes following the bivariate exponential distribution of Sarkar(1987) using inverse power rule model. Also we derived the maximum likelihood estimators of parameters for asymptotic normality. We compare the mean square error of the proposed estimator for the life distribution under use conditions stree through Monte Carlo simulation.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.643-647
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• 2003

Power plant Piping operating at elevated temperature often fails prematurely by the growth of microcracks under creep conditions. Therefore, the life assessment of high temperature components that contain cracks is an important technological problem. The mechanisms of crack growth in simple metals and alloys have been investigated using both mechanical and microstructural approaches. In this study, life prediction accounting for creep, crack growth and thermal stress is analyzed.

• Corrosion Science and Technology
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• v.4 no.5
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• pp.171-177
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• 2005

A comprehensive framework for numerical simulation of time-dependent performance change of reinforced concrete (RC) structures subjected to chloride attack is presented in this paper. The system is composed of simplified computational models for transport of moisture and chloride ions in concrete pore structure and crack, corrosion of reinforcement in concrete and mechanical behavior of RC member with reinforcement corrosion. Service-life of RC structures under various conditions is calculated.