• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.292-292
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• 2014

Wide band gap semiconductors, such as III-nitrides (GaN, AlN, InN, and their alloys), SiC, and diamond are expected to play an important role in the next-generation electronic devices. Specifically, GaN-based high electron mobility transistors (HEMTs) have been targeted for high power, high frequency, and high temperature operation electronic devices for mobile communication systems, radars, and power electronics because of their high critical breakdown fields, high saturation velocities, and high thermal conductivities. For the stable operation, high power, high frequency and high breakdown voltage and high current density, the fabrication methods have to be optimized with considerable attention. In this study, low ohmic contact resistance and smooth surface morphology to AlGaN/GaN on 2 inch c-plane sapphire substrate has been obtained with stepwise annealing at three different temperatures. The metallization was performed under deposition of a composite metal layer of Ti/Al/Ni/Au with thickness. After multi-layer metal stacking, rapid thermal annealing (RTA) process was applied with stepwise annealing temperature program profile. As results, we obtained a minimum specific contact resistance of $1.6{\times}10^{-7}{\Omega}cm2$.

• Korean Journal of Medicinal Crop Science
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• v.21 no.1
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• pp.54-60
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• 2013

According to previous reports, antioxidant activities of Codonopsis lanceolata could be increased by a steaming process. This study was performed to improve its antioxidant activity and skin whitening activities of C. lanceolata by high pressure and stepwise steaming complex process. The complex processed C. lanceolata showed highest free radical scavenging acitivity as 45.21%, and for phenol and flavonoid contents, complex processed C. lanceolata contained higher than those from conventional extraction process or steaming process alone. The Cytotoxicity of all C. lanceolata extracts also showed low cytotoxicity against human fibroblast cell (CCD-986sk) as 4.49 ~ 10.40%. In whitening activity, high inhibition of tyrosinase activity was estimated as 25.08% by adding the extracts from complex process. We found that whitening and antioxidant activity of complex processed C. lancolata extract was higher than those obtained from conventional extraction and a steaming process because various kinds of antioxidant compounds could be easily released by combined process, compared to one of each process.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.276-282
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• 2003

The geoscientific study on geological disposal for radioactive wastes has established the stepwise site characterization program, methods and investigation technology. However the intrinsic properties of geological material such as heterogeneity and scale dependent properties make difficulty on satisfactory understanding of geological conditions. To avoid unnecessary time delay and unexpected extra-cost for site investigation, the accurate and complete site investigation program should be established in a stepwise manner and the QC programs for investigation methods and procedures. Moreover, the technical requirements and preferences for a repository should be distinguished and be assessed at the end of each investigation step.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2828-2836
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• 2015

Evaluation items were deducted by based on literature materials to supplement the evaluation system of rock cut-slope in national road. Delphi survey of experts were conducted to review the final evaluation items. As a result of reviewing the significance through stepwise multiple linear regression, all of deducted items were statistically significant because these had lower P-value than 0.05. And It was confirmed that the items were selected appropriately as they had relatively similar levels of the weight. In consideration of CVR and reliability both suggested items and existing items, the exclusible items was selected and new items can complement existing evaluation system were added. Finally 18 rock cut-slope evaluation items was deducted.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.269-273
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• 2006

Multiple linear regression analysis was conducted to interpretate the relationship between sesame grain yield and its components under early sowing cropping condition. The t test showed that stem length, number of capsules per plant, 1000 seeds weight and seed weight per plant gave significant contribution to sesame grain yield, therefore those variables were assumed to mostly influenced components to grain yield of sesame. In the stepwise regression analysis, the predicted equation for sesame grain yield per square meter (Y) was Y = -7.900 + 0.150X1 + 0.461X5 + 15.553X6 + 8.543X7. Meanwhile, F value showed that stem length, number of capsules per plant and seed weight per plant gave significant contribution to sesame grain yield, while 1000 seeds weight did not significantly show. Based on the results, it is reasonable to assume that high yield. potential of sesame under early sowing cropping condition would be obtained by selecting breeding lines with long stem length, number of capsules per plant, and seed weight per plant, which was different result at the late sowing cropping condition in which days to flowering and maturity were assumed to be more affected factors to the sesame grain yield.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.1
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• pp.143-153
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• 2003

This study was conducted in order to provide basic study material for children's garment design. The subjects of this study are fifth and sixth grade elementary school girls, who demonstrate rapid growth and the differences among individual somatic types are apparent. Their bodies are studied, categorized into patterns and the characteristics are examined. 1 The increase of height and length measurements according to age increase are much larger than that of breadth, depth and girth menasurments. 2. Eight factors are drawn upon factor analysis and the rate of factors comprisedare 78.68%. 3. The shapes of lower body of higher grades girls in elementary school are classified into three categories. The first type is slender in lower body and the second type is more contoured around waist area with longer length and higher height than the average elementary school girls. The third type is heavy in the lower body. 4. Eighteen items important for somatic categorization are selected through stepwise discriminant analysis and the exactitude rate of these items is 93.3%.

• Korean Journal of Health Education and Promotion
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• v.21 no.4
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• pp.109-119
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• 2004

This study was conducted to examine factors influencing mental health of middle-aged adults(N=203) in relation to sociodemographic variables, health behaviors, and social support. The survey with questionnaire was carried out for the subjects of the residents in two communities of a local city located in Gangwon-do, Korea from September 3 to 15, 2003. Data analysis procedure included stepwise multiple regression using mental health as the dependent variable, and sociodemographic variables, health behaviors, and social support as independent variables. There were significant differences in the mental health by birth place(t=-1.67, p<0.10), religion (t=2.27, p<0.05) and subjective economic status(F=2.29, p<0.10). Mental health showed significant positive correlations with both health behavior (r=0.462, p<0.001) and social support (r=0.142, p<0.05). Stepwise multiple regression analysis for mental health revealed that the most powerful predictor was health behavior(β=0.453, p<0.001). Health behavior and religion explained 24％ of the variance. The results suggest the necessity of a intervention that considers the health behaviors should be included in middle-aged adults so as to promote mental health.

• The Korean Journal of Rehabilitation Nursing
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• v.17 no.2
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• pp.97-103
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• 2014

Purpose: This study was conducted to identify the knowledge, attitude, and preventive health behavior of cancer in middle-aged men and to provide data for education program regarding cancer prevention. Methods: This study was a descriptive research using a questionnaire, which included 20 items for knowledge, 10 items for attitude, and 18 items for preventive health behavior of cancer. Data were collected from 140 middle-aged men. Descriptive statistics, t-test, one-way ANOVA and Pearson's correlation coefficients, and stepwise multiple regression analysis were used with SPSS/WIN 18.0 to analyze the data. Results: The mean score for knowledge of cancer was 11.58 (range 0~20), for attitude, 37.52 (range 5~50), and for preventive health behavior of cancer, 58.85 (range 18~90). Preventive health behavior of cancer showed a significantly positive correlation with knowledge (r=.27, p=.001) and attitude (r=.31, p<.001) toward cancer. In stepwise multiple regression analysis, knowledge and attitude toward cancer were significant factors affecting preventive health behavior of cancer. Those variables explained 12.5% of cancer preventive behavior. Conclusion: In order to develop a cancer prevention education program for middle-aged men, accurate knowledge and improving attitude should be considered. Furthermore, it is necessary to do further study with a larger random sample according to lifespan.

• KIEE International Transactions on Power Engineering
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• v.2A no.3
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• pp.121-128
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• 2002

This study proposes a new method for transmission system expansion planning using fuzzy integer programming. It presents stepwise cost characteristics analysis which is a practical condition of an actual system. A branch and bound method which includes the network flow method and the maximum flow - minimum cut set theorem has been used in order to carry out the stepwise cost characteristics analysis. Uncertainties of the permissibility of the construction cost and the lenient reserve rate and load forecasting of expansion planning have been included and also processed using the fuzzy set theory in this study. In order to carry out the latter analysis, the solving procedure is illustrated in detail by the branch and bound method which includes the network flow method and maximum flow-minimum cut set theorem. Finally, case studies on the 21- bus test system show that the algorithm proposed is efficiently applicable to the practical expansion planning of transmission systems in the future.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.350-353
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• 2001

This study proposes a new method for the transmission system expansion planning using the fuzzy integer programming. It presents stepwise cost characteristics analysis which is a practical condition of an actual systems. A branch and bound method which includes the network flow method and the maximum flow-minimum cut set theorem has been used in order to proceed the stepwise cost characteristics analysis. Uncertainties of the permission of the construction cost and not strict reserve rate and load forecasting of expansion planning have been included and also processed using fuzzy set theory in this study. In order to proceed the latter analysis, the solving procedure is illustrated in detail by branch and bound method which includes the network flow method and maximum flow-minimum cut set theorem. Finally, case studies on 21-bus test system show that the algorithm proposed is efficiently applicable to the practical expansion planning of transmission systems in future.