• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.483-488
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• 2014

The nucleophilic substitution reactions of Y-aryl methyl (8) and Y-aryl propyl (10) chlorothiophosphates with X-pyridines are studied kinetically in acetonitrile at $35.0^{\circ}C$. The Hammett and Bronsted plots with X in the nucleophiles for both substrates exhibit biphasic concave upwards with a break region between X = 3-Me and H. The obtained values of the cross-interaction constants (${\rho}_{XY}$) are negative with 8 while positive with 10 despite the same free energy correlations with X for both substrates. A stepwise mechanism with a rate-limiting bond formation is proposed with 8, whereas a stepwise mechanism with a rate-limiting leaving group departure from the intermediate is proposed with 10 based on the sign of ${\rho}_{XY}$, negative and positive with 8 and 10, respectively. A frontside nucleophilic attack is proposed with strongly basic pyridines based on the considerably great magnitudes of ${\rho}_X$ and ${\beta}_X$ values while a backside attack is proposed with weakly basic pyridines based on the relatively small magnitudes of ${\rho}_X$ and ${\beta}_X$ for both substrates.

• The Korean Journal of Applied Statistics
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• v.26 no.6
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• pp.915-922
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• 2013

Quantile regression can estimate multiple conditional quantile functions of the response, and as a result, it provide comprehensive information of the relationship between the response and the predictors. However, when estimating several conditional quantile functions separately, two or more estimated quantile functions may cross or overlap and consequently violate the basic properties of quantiles. In this paper, we propose a new stepwise method to estimate multiple non-crossing quantile functions using constraints on the kernel coefficients. A simulation study are presented to demonstrate satisfactory performance of the proposed method.

• Korean Journal of Human Ecology
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• v.17 no.5
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• pp.807-819
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• 2008

The purpose of this study was to find out the factors which were related to the delinquent behaviors among 2nd years high school in Geoje, Korea. The subjects were 618 high school students. Data were collected by self-reported questionnaires from March to April, 2007. Data were analyzed by SPSS WIN 12.0 program with mean, standard deviation, t-test, ANOVA, Kruskal-Wallis test, Scheffe's test, Pearson's correlation, and stepwise multiple regression. Students' delinquent behaviors differed by experience of smoking, experience of drinking, harmony of family, mother's education, father's smoking mother's smoking, academical class, satisfaction of school-life, friends who smoked, drank alcohol, did drugs, and punished friends. Students' stress and depression had positive correlation with their delinquent behaviors. The result of stepwise multiple regression showed that punished friends, experience of smoking, depression, father's smoking satisfaction of school-life were significant related factors to delinquent behaviors among high school students. It is necessary for home, school, and community to cooperate with each other in preventing high school students from delinquent behaviors.

• Korean Journal of Health Education and Promotion
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• v.21 no.2
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• pp.187-198
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• 2004

The purpose of this study was to investigate knowledge, attitudes and the ability of women toward breast self-examination and to identify factors that may influence the ability of breast examination. The subjects for this study were 105 women in a community health center located in Busan. Data was collected during the period from September I to 20, 2002 by means of a structured questionnaire. The data was analyzed using the SPSS WIN 10.0 program and included descriptive statistics, Pearson correlation coefficient and stepwise multiple regression. The results of study are as follows： 1. The mean knowledge score for the total sample was 9.62 and the mean attitude score was 62.95. The mean self- practice score was 5.79. 2. Women's knowledge about breast self-examination was significantly related to attitudes and the ability of women toward breast self-examination (p＜0.05). 3. The ability of women toward breast self-examination was significantly related to attitudes about breast self-examination (p＜0.05). 4. According to the results of stepwise multiple regression analysis, factors affecting women's ability of breast self-examination were practice of breast self-examination and level of education and explained 19.7％ of variance. From the results of this study it can be said that women need to be taught proper breast self-examination so that they can become more proficient in detecting breast abnormalities.

• Korean Journal of Community Nutrition
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• v.8 no.6
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• pp.910-918
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• 2003

The purposes of this study were to develop a model for university foodservices and to provide management strategies for reducing costs, and increasing productivity and customer satisfaction. The results of this study were as follows : 1) The demands in university food services varied depending on the time series. A fixed pattern was discovered for specific times of the month and semesters. The demand tended to constantly decrease from the beginning of a specific semester to the end, from March to June and from September to December. Moreover, the demand was higher during the first semester than the second semester, within school term than during vacation periods, and during the summer vacation than the winter. 2) Pearson's simple correlation was done between actual customer demand and the factors relating to forecasting the demand. There was a high level of correlation between the actual demand and the demand that had occurred in the previous weeks. 3) By applying the stepwise multiple linear regression analysis to two different university food services providing multiple menu items, a model was developed in terms of four different time series(first semester, second semester, summer vacation, and winter vacation). Customer preference for specific menu items was found to be the most important factor to be considered in forecasting the demand.

• Research in Community and Public Health Nursing
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• v.13 no.3
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• pp.523-531
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• 2002

Purpose: The purpose of this study was to assess the importance and sensitivity to nursing interventions of six sensitive nursing outcomes selected from the Nursing Outcomes Classification. The outcomes in this study were Self-Care: Activities of Daily Living, Self-Care: Instrumental Activities of Daily Living, Treatment Behavior: Illness or Injury, Knowledge: Health Promotion, Caregiver Performance: Direct Care, and Caregiver Physical Health. Method: Data were collected from 97 visiting nurses working in public health centers located in a province and a capital city. The Fehring method was used to estimate outcomes and indicators for content validity. Simultaneous multiple regression and stepwise regression were used to evaluate relationships between each outcome and its indicators. Results: Results confirmed the importance and nursing sensitivity of the outcomes and their indicators. Multiple regression revealed key indicators of each outcome. Self-Care: Instrumental Activity of Daily Living needed to be revised. Neither all of the indicators nor the indicators showing the highest importance and contribution ratio were selected as independent variables for the stepwise regression model. The R2 of the regression models ranged from 29 to 56% in importance by selected indicators and from 56 to 83% in contribution. Conclusion: Further research is needed for the revision of outcomes and their indicators.

• Research in Community and Public Health Nursing
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• v.23 no.4
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• pp.366-375
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• 2012

Purpose: The purpose of this study was to identify predictors of drinking problems in Korean international students in the United States. Methods: The subjects involved this study were 190 Korean international students in the United States. Data were measured using a drinking problems questionnaire, an acculturative stress scale for international student, and the CES-D. The collected data were analyzed using the SPSS/WIN 17.0 program to calculate mean, standard deviation, ANOVA, Sheff$\acute{e}$ test and pearson's correlation coefficient. and stepwise multiple regression. Results: 1) The mean score of the degree of perceived acculturative stress was $2.15{\pm}0.63$, of depression was $17.67{\pm}9.85$, and of drinking problems was $15.03{\pm}15.52.2$) There were significant correlations between acculturative stress and drinking problems (r=.506, p<.001), between depression and drinking problems (r=.6726, p<.001), and between acculturative stress and depression (r=.453, p<.001). 3) In stepwise multiple regression analysis the most powerful predictor of drinking problems were acculturative stress (${\beta}$=.243, p<.001), and depression (${\beta}$=.562, p<.001). Conclusion: Based on the results, practical implications for reducing the acculturative stress and improving the psychological well-being of Korean students were discussed.

• Research in Community and Public Health Nursing
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• v.24 no.4
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• pp.480-487
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• 2013

Purpose: The purpose of this study was to investigate the relationship among family functioning, empathy and aggression by high school students. Methods: This was a descriptive study. The survey participants were 467 high school students from M city. Data were collected from November 29 to December 7, 2012 and self-report questionnaires including a Family Adaptability Cohesion Evaluation Scale, Interpersonal Reactivity Indexes, and an Aggression Questionnaire. The collected data were analyzed by descriptive statistics, independent-samples t-test, ANOVA, stepwise multiple regression. Results: The majority of the subjects were 2nd graders (42.0%) and female (57.2%). 59.7% of the subjects had religion, 84.8% were living together with parents. The mean ages of their fathers and mothers were $49.90{\pm}0.20$ and $46.85{\pm}0.19$ respectively. Aggression was found to have a statistically negative correlation with family functioning and empathy. Stepwise multiple regression analysis revealed that the most powerful predictor of aggression was empathic concern. Empathic concern, family cohesiveness, perspective taking, personal distress and gender accounted for 16.7% of the variances. Conclusion: It is necessary to provide aggressiveness reduction programs for high school students that consider their family functioning and empathy.

• Journal of Korean Public Health Nursing
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• v.22 no.1
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• pp.84-96
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• 2008

Purpose: To consider how college students' adjustment to college life is related to peer attachment and self-esteem. Method: The subjects were 183 female college students attending one university. The study data were collected with the inventory of peer attachment-revised version, the self-esteem inventory, and the inventory for adjustment to college life. The data were analyzed by t-test, ANOVA, Pearson correlation coefficient and stepwise multiple regression. Results: There were significant differences in self-esteem according to residence type. There were significant differences in the adjustment to college life according to monthly income. There was a significantly positive correlation between peer attachment and adjustment to college life. There were significantly positive correlations between self-esteem and adjustment to college life and all of the subscales of adjustment to college life. Stepwise multiple regression analysis showed that 28.6% of the adjustment to college life was significantly explained by self-esteem and monthly income. Conclusion: Based on these findings, peer attachment is a very important factor influencing self-esteem which is itself a very important factor influencing adjustment to college life in female college students. Therefore, an alternative program designed to increase the self-esteem and peer attachment of female college students should be a planned program based on the study results.

• Journal of Korean Academy of Nursing
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• v.32 no.5
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• pp.684-693
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• 2002

This study was conducted to detect the correlations and the main factors influencing self-directedness in learning of nursing students. Method: The samples were composed of 224 nurse students who were from three nursing department in Seoul, Chungnam & Kyunbook. The reliability of 4 instruments was tested with Cronbach's $\alpha$ from .63 to .86. The data was analyzed using a SAS program for descriptive statistics, Pearson correlation coefficients and stepwise multiple regression. Result: The results were as follows: 1. The mean self-directedness score was 91.23 which was slightly high. The self-directedness in learning was influenced significantly by grade, perception of self-level, self-study in majoring and self-study except for majoring(F= 3.33-7.14, p<.05). 2. There were significant correlations between all the predictive variables and the self-directedness(r=.27-48, p<.01). 3. Stepwise multiple regression analysis showed that 35% of the self-directedness in learning of nursing students were significantly explained by self-esteem(23%), locus of control(6%), self-study except for majoring(2 kind, 2%), self study in majoring(good, 2%), and self-study except for majoring( above 3 kind, 2%). Conclusion: Based upon these findings, sociopsychological variables like self-esteem and locus of control are very important factor influencing self-directedness in learning of nursing students.