• Journal of Korea Foundry Society
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• v.35 no.2
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• pp.36-43
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• 2015

In this study, the influences of aluminum and tin additions (individual and combined) on corrosion behavior of magnesium alloy have been determined. The studied alloys were fabricated by permanent mold casting method to measure the corrosion properties, a potentiodynamic test, hydrogen evolution test and immersion test were carried out in a 3.5% NaCl solution at pH 7.2. From the results of microstructure analysis, the Mg-9Al-1Zn alloy was found to be composed of ${\alpha}$-Mg and rod-like $Mg_{17}Al_{12}$ phase and the Mg-5Sn-5Al-1Zn alloy was found to be composed of ${\alpha}$-Mg, rod-like $Mg_{17}Al_{12}$ and $Mg_2Sn$ phases. In the case of the Mg-9Sn-1Zn alloy, the microstructure was composed of ${\alpha}$-Mg and eutectic $Mg_2Sn$ phase. With Sn addition (individual and combined), the corrosion resistance of the Mg alloys improved.

• Communications for Statistical Applications and Methods
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• v.17 no.1
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• pp.79-88
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• 2010

Introductory statistic class proposes two tests for the equality of two population means according to the homogeneity of their variances. However, in practice, the variances are also unknown and practitioners often test their homogeneity before they do two sample t-test. This is also true in many popular statistical packages such as SAS and SPSS. In this paper, we study the type I error of this two stage procedure and propose a procedure to control it at a given significance level.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.498-504
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• 1992

In order to investigate the antimutagenicity of the sweet potato enzymatic browning reaction products (SPEBRP) were studied the DNA breaking action, spore rec assay and Ames test. In the DNA breaking action of reaction mixture of SPEBRP and polyphenol compounds with an agarose horizonal electrophoresis, catechol (CAT)-SPEBRP and hydroxyhydroquinone (HHQ)SPEBRP inhibited DNA breaking effect in the presence of $Fe^{2+}$. In the spore ree assay using Bacillus subtilis H17(rec+) and M45(rec-), 3,4-dihydroxytoluene (DHT)-SPEBRP showed strong antimutagenic effects on MNNG. In the Ames test using Salmonella tYPhimurium TA 98 and TA 100, pyrogallol(PYR)-, 3,4-dihydroxytoluene (DHT)- and hydroxyhydroquinone (HHQ)-SPEBRPs suppressed about 67%, 71% and 63% in the mutagenesis induced by Benzo($\alpha$)Pyrene(B($\alpha$)p).

• Korean Journal of Materials Research
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• v.7 no.6
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• pp.510-516
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• 1997

반응성RF 마그네트론 스퍼터링 법으로 상온에서 c-축으로 우선 배향된 AIN 박막을 여러 기판 위에 증착하였다. SiO$_{2}$/Si, Si$_{3}$N $_{4}$Si, Si(100), Si(111)그리고 $\alpha$-AI$_{2}$O$_{3}$(0001) 기판에서 AIN(0002)로킹커브 피크의 표준편차는 각각 2.6˚, 3.1˚2.6˚, 2.5˚ 그리고 2.1˚ 의 값을 나타내었다. $\alpha$-AI$_{2}$O$_{3}$(0001) 기판에 증착된 AIN박막은 epitaxial 성장을 나타내었다. Si기판에 증착된 AIN박막에서 측정된 비저항과 1MHz 주파수에서 측정된 유전상수의 값은 각각 $10^{11}$Ωcm와 9.5였다. IDT/AIN/$\alpha$-AI$_{2}$O$_{3}$(0001)구저를 갖는 지연선 소자의 표면 탄성과 특성을 측정하였다. 상 속도, 전기기계 결합계수 그리고 전파손실은 H/λ가 0.17-0.5 범위에서 각각 5448-5640m/s, 0.13-0.17% 그리고 0.41-0.64dB/λ의 값을 나타내었다.다.

• Development and Reproduction
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• v.13 no.3
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• pp.163-172
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• 2009

Some organotin compounds such as butyltins and phenyltins are known to induce impo-sex in various marine animals and are considered to be endocrine disruptors. In this study, the effect of organotins on follicular steroidogenesis in amphibians was examined using ovarian follicles of Rana dybowskii and Rana catesbeiana. Isolated follicles were cultured for 6 or 18 h in the presence and absence of frog pituitary homogenate (FPH) or various steroid precursors, and the levels of product steroids in the culture media oassay. Among the butyltin compounds, tributyltin (TBT) strongly and dose-dependently inhibited the FPH-induced synthesis of pregnenolone ($P_5$) and progesterone ($P_4$) by the follicles. TBT also strongly suppressed the conversion of cholesterol to $P_5$ and partially suppressed the conversion of $P_5$ to $P_4$. A high concentration of dibutyltin (DBT) also inhibited steroidogenesis by the follicles while monobutyltin and tetrabutyltin had negligible effects. The toxic effect of TBT or DBT was irreversible and a short time of exposure (30 min) was enough to suppress steroidogenesis. All the phenyltin compounds significantly inhibited FPH-induced $P_5$ synthesis by the follicles. The effective dose of 50% inhibition by diphenyltin was $0.04\;{\mu}M$ and those of monophenyltin and triphenyltin were $0.24\;{\mu}M$ and $0.3\;{\mu}M$, respectively. However, none of the phenyltin compounds significantly suppressed the conversion of $P_4$ to $17{\alpha}$-hydroxyprogesterone ($17{\alpha}$-OHP) (by $17{\alpha}$-hydroxylase), $17{\alpha}$-OHP to androstenedione (AD) (by $C_{17-20}$ lyase), or AD to testosterone by the follicles. Taken together, the data show that among the steroidogenic enzymes, P450scc in the follicles is the most sensitive to organotin compounds and that an amphibian follicle culture system can be a useful screening model for endocrine disruptors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.5 no.1
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• pp.25-30
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• 1976

In this investigation, the physico-chemical properties of Korean cattles milk and Holstein cows milk are studied. The results of the milk -protein of F-1, F-2, and F-4 hybrid are interested in this studied. 1. The physico-chemical properties of Korean cattle and Holstein cows milk is summarized at Table 1, Table 2. 2. The electrophoretic milk protein fraction of Korean cattle is identified : Lactoalbumin 1.74mg%. Alpha-1 globulin 1.19mg%, Alpha-2 globulin 0.68mg%, Beta-globulin 2.57mg%, Gamma-globulin 0.93mg%. 3. The electrophoretic milk protein fraction of Holstein cow : Lactoalbumin 1.23mg%, Alpha-1 globulin 0.93mg%, Alpha-2 globulin 0.86mg%, Bata-globulin 2.56mg%, Gamma-globulin 1.74mg% have been identified. 4. The electrophoretic milk protein fraction of hybrid F-1, F-2, and F-4 between Korean cattle(female) and Holstein(male) is obtained the following : F-1 hybrid : Lactoalbumin 1.38mg%, Alpha-1 globulin 1.58mg%, Alpa-2 globulin 2.46mg%, Beta-globulin 1.39mg%. F-2 hybrid : Lactoalbumin 1.57mg%, Alpha-1 globulin 1.74mg%, Alpha-2 globulin 2.19mg%, Beta-globulin 1.74mg%. F-4 hybrid : Lactoalbumin 2.46mg%, Alpha-1 globulin 1. 24mg%, Alpha-2 globulin 1.57㎎%, Beta-globulin 1.74mg%.

• Proceedings of the Korean Society of Crop Science Conference
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• 1988.07a
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• pp.16-17
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• 1988

• Archives of Pharmacal Research
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• v.17 no.1
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• pp.5-10
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• 1994

From the methanolic extract of aerial parts of Clematis koreana var. umbrosa, one new triterpenoidal saponin, 3-O-${\beta}$-D-xylopyranosyl(1-3)-${\alpha}$-L-arabinopyranosyl oleanolic acid 28-O-${\alpha}$-L-rhamnopyranosyl(1-4)-${\beta}$-glucopyranosyl(1-6)-${\beta}$-glucopyranosyl ESTER, along with five known aromatic compounds and two known triterpenoidal saponins were isolated.

• Journal of Industrial Technology
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• v.6
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• pp.13-17
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• 1986

The effect of supersaturation on morphology of silicon carbide by chemical vapor deposition using $CH_3SiCl_3-H_2$ gas mixture system was investigated. The experimental results show that the final structure of silicon carbide deposits is coarser as total pressure increases or ${\alpha}$-ratio decreases. It is believed because supersataration of Si-source decreases as total pressure increases or ${\alpha}$-ratio decreases.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.23-23
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• 2003

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and other aryl hydrocarbon (AhR) ligands suppress 17${\beta}$-estradiol (E)-induced responses in the rodent uterus and mammary tumors and in human breast cancer cells. Treatment of ZR-75, T47D and MCF-7 human breast cancer cells with TCDD induces proteasome-dependent degradation of endogenous estrogen receptor ${\alpha}$ (ER${\alpha}$).(omitted)