• The Korean Journal of Applied Statistics
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• v.21 no.1
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• pp.141-149
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• 2008

Recently we frequently analyze multivariate data with quite large number of variables. In such data sets, virtually duplicated variables may exist simultaneously even though they are conceptually distinguishable. Duplicate variables may cause problems such as the distortion of principal axes in principal component analysis and factor analysis and the distortion of the distances between observations, i.e. the input for cluster analysis. Also in supervised learning or regression analysis, duplicated explanatory variables often cause the instability of fitted models. Since real data analyses are aimed often at multiple purposes, it is necessary to reduce the number of variables to a parsimonious level. The aim of this paper is to propose a practical algorithm for selection of a subset of variables from a given set of p input variables, by the criterion of minimum trace of partial variances of unselected variables unexplained by selected variables. The usefulness of proposed method is demonstrated in visualizing the relationship between selected and unselected variables, in building a predictive model with very large number of independent variables, and in reducing the number of variables and purging/merging categories in categorical data.

• Korean Security Journal
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• no.41
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• pp.123-151
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• 2014

The purpose of this study was focused on the relationship between private guards' job embeddedness and dual commitment. In this study, job embeddedness is selected as an independent variable and dual commitment is selected as a dependent variable one. job embeddedness was divided into three sub-factors such as "fit", "links", and "sacrifice", and dual commitment is again composed with organizational commitment, and career commitment. Moreover sex, age, academic background, service period, and income were selected as a control variable. To test the hypotheses, survey data from private guards in Kyungpook are collected and analyzed. Principal component method is used to see which items cluster together in each factor and to calculate factor scores. Multiple regression analysis identifies several factors which have significant effects on dual commitment. Key finding can be summarized as follow. Fist, the factor of "fit" have significant effects on organizational commitment, and career commitment. Second, the factor of "links" have significant effects on organizational commitment, and career commitment. Third the factor of "sacrifice" have significant effects on organizational commitment, and career commitment. Finally, when all the variables with significant effects are included in the final model, "links" disappear, while "fit" and "sacrifice" remain statistically significant. Based on these finding, this study suggests some policy issues to promote private guards' dual commitment.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.4101-4101
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• 2001

Information of body composition (fat and protein) in living animal is important to determine the nutrients requirement. Deuterium oxide (D2O) dilution techniques, as one of isotope dilution techniques have been useful for the prediction of body composition. However, the determination of D2O concentration is time consuming and complicated. Therefore this study was conducted to develop a new method to predict D2O concentration in plasma using near infrared spectroscopy technique (NIRS). Four dairy cows in early lactation were used. They were fed total mixed ration containing conr silage, timothy hay, and concentrates to make 17.0%CP and 14.0 MJDE/kgDM. Dosing D2O was at week 1,3 and 5 after parturition. After dosing D2O, the blood was collected from hour 0 to 72. Blood samples were then centrifuge at 3,000 rpm for 10 minutes to obtain plasma. D2O concentration was analyzed by gas chromatograph (deuterium oxide analyzable system, HK102, Shokotsusyou) after extracted from plasma by liophilization. Plasma sample was scanned by NIRS using Pacific Scientific (Neotec) model 6500 (Perstorp Analytical, Silver Spring, MD) in the range of wavelength from 1100 to 2500 nm. Calibration equation was developed using multiple linear regression. Sample from one animal (cow #550; n: 74) was used for developing the calibration while the rest three animals were used for validating the equation. The range, R and SEC of the calibration set samples were 135-925 ppm, 0.93 and 48.1 ppm, respectively. Validation of the calibration equation for three individual cows was done and the average of NIR predicted value of D2O at each collection time from three weeks injection showed a high correlation. The range, r and 53 of plasma from cow #474 were 322-840 ppm,0.93 and 53.1; cow #478 were 146-951 ppm,0.95 and 39.8; cow #942 were 313-885 ppm,0.95 and 37.2, respectively. Judgement of accuracy based on ratio of standard deviation and standard error in validation set samples (RPD) for cow #474, #478 and #942 were 2.2,4.3 and 3.4, respectively. The error in application due to the variation between individual was considered smaller than the bias from collection period, however, this prediction can be overcome with correction of standard zero-minute concentration of blood. The results of this preliminary study on the use of NIRS for determination of D2O in plasma showed very promising as shown by a convenient and satisfy accuracy. Further study on various physiological stage of animal should be done.

• Journal of the Korean Society of School Health
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• v.16 no.2
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• pp.1-11
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• 2003

PURPOSE: The aim of our study was to assess the prevalence of respiratory symptoms and to determine their environmental risk factors in school children living in a city where traffic is particularly heavy. METHODS: From November 12th to November 19th, 2002, we sent questionnaires to parents for children's health and environmental factors, and ninety eight percent (516) of parents responded. RESULTS: The lifetime prevalence of chronic respiratory illness was 12.2% and 13.2% for wheeze, and 6.6% for physician diagnosed asthma. Using multiple logistic regression model, we found that family history of asthma(OR=3.47, 95% CI 1.36-8.78), atopy dermatitis(OR=5.48, 95% CI 2.37-12.66), and pets at home(OR=3.22, 95% CI 1.26-8.23) were associated with chronic respiratory illness in last 12 months. We also found that family history of asthma(OR=3.28, 95% CI 1.16-9.31), atopy dermatitis(OR=2.89, 95% CI 1.11-7.54), and short distance between the house and road(OR=2.85, 95% CI 1.03-7.87) were associated with asthma in last 12 months. CONCLUSIONS: Elementary school children in a city had a relatively high prevalence of chronic respiratory illness and symptoms. In addition to genetic factors, pets at home and outdoor air pollution are associated with respiratory illness and Symptoms in school children.

• Research in Community and Public Health Nursing
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• v.10 no.2
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• pp.330-346
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• 1999

This descriptive correlational study was conducted to identify the variables related to a health promoting lifestyle in high school students. 304 high school students and 189 vocational high school students living in Taegu city were selected by a convenience sampling method. The data were collected by self-reported questionnaires from August 24 to September 4, 1998. Pender and others' Health Promoting Lifestyle Profile, Shere et al's. Self-Efficacy scale, Wallston et al.'s Internal Health Locus of Control scale, Wares' Health self rating scale and Cohen & Hoberman's Social support scale were used. The data were analyzed by using descriptive statistics, Pearson correlation coefficient, t-test, MANOVA, ANOVA. Tukey verification and Stepwise multiple regression with an SAS program. The results of this study were as follows: 1. The average score of a health promoting lifestyle performance was 2.38(SD=.36) of a 4 point scale .Self-actualization (mean = 2.80. SD = .60). interpersonal support(mean = 2.73, SD=.47), health responsibility (mean=1.53, SD=.47), nutrition(mean=2.64, SD=.63), exercise(mean=2.71. SD=.72) and stress management(mean=2.37, SD=.58) were also analyzed. 2. The combination of self-efficacy, social-support, internal health locus of control. father's educational level and perceived health status explained 37.97% of the variance in health promoting lifestyles. 3. A Health promoting lifestyle showed significant positive correlations with self efficacy(r=.5173. p=.0011), perceived health status(r=.254, p=.001) and internal health locus of control(r=.321. p=.001). 4. According to sex(t=7.38. p=.006). economic state(F=6.62, p=.00l), Father's educational level(F=4.25, p=.005), mother's educational level(F=6.94. p=.000l), the grade of educational performance(F=3.74, p=.024), sleeping hours(F=3.47. p=.032) and social support(F=40.76, p=.0001). there were significant differences and modifying factors in health promoting lifestyles. On the basis of the above findings. self-efficacy in cognitive factors, and social support in modifying factors were identified as the variables which explained most of Pender's health-promotion model. Nursing strategies enhancing self-efficacy and social support which have a more significant effect on health promoting lifestyles should be developed. Further research is required to find out the factors influencing health pormoting lifestyle of high school students.

• Journal of the Korean earth science society
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• v.22 no.5
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• pp.415-422
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• 2001

Studies of atmospheric general circulation in the troposphere and stratosphere are very important to understand the influence of human activities on the global climate and its change. Recently, the existence of an annual cycle in the circulation has been reported by a number of studies. In this study, the residual mean meridional circulation is calculated by the TEM momentum and continuity equations for the period from December 1985 to November 1995 (10 years), and the long-term variations of the circulation and mass fluxes across the 100hPa surface are examined. The multiple regression statistical model is used to obtain quantitatively the long-term variations. This study is focused especially on mean meridional circulation in the troposphere and stratosphere associated with ENSO (El Ni${\tilde{n}}$o-Southern Oscillation) which is known as a cause of the unusual weather, global climate, and its change. The results show that the global scale troposphere-stratosphere mean meridional circulation is intensified during El Ni${\tilde{n}}$o event and QBO (quasi-biennal oscillation) easterly phase and weakened during La Ni${\tilde{n}}$o event and QBO westerly phase. The signal of Mount Pinatubo volcanic eruption in June 1991 is obtained. Due to the volcanic eruption the global scale troposphere-stratosphere mean meridional circulation is abruptly intensified.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.221-237
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• 2005

For developing the site-specific fertilizer management strategies of crop, it is essential to know the spatial variability of soil factors and to assess their influence on the variability of crop growth and yield. In 2002 and 2003 cropping seasons within-field spatial variability of rice growth and yield was examined in relation to spatial variation of soil properties in the· two paddy fields having each area of ca. $6,600m^2$ in Suwon, Korea. The fields were managed without fertilizer or with uniform application of N, P, and K fertilizer under direct-seeded and transplanted rice. Stable soil properties such as content of clay (Clay), total nitrogen (TN), organic mater (OM), silica (Si), cation exchange capacity (CEC), and rice growth and yield were measured in each grid of $10\times10m$. The two fields showed quite similar spatial variation in soil properties, showing the smallest coefficient of variation (CV) in Clay $(7.6\%)$ and the largest in Si $(21.4\%)$. The CV of plant growth parameters measured at panicle initiation (PIS) and heading stage (HD) ranged from 6 to $38\%$, and that of rice yield ranged from 11 to $21\%$. CEC, OM, TN, and available Si showed significant correlations with rice growth and yield. Multiple linear regression model with stepwise procedure selected independent variables of N fertilizer level, climate condition and soil properties, explaining as much as $76\%$ of yield variability, of which $21.6\%$ is ascribed to soil properties. Among the soil properties, the most important soil factors causing yield spatial variability was OM, followed by Si, TN, and CEC. Boundary line response of rice yield to soil properties was represented well by Mitcherich equation (negative exponential equation) that was used to quantify the influence of soil properties on rice yield, and then the Law of the Minimum was used to identify the soil limiting factor for each grid. This boundary line approach using five stable soil properties as limiting factor explained an average of about $50\%$ of the spatial yield variability. Although the determination coefficient was not very high, an advantage of the method was that it identified clearly which soil parameter was yield limiting factor and where it was distributed in the field.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.343-352
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• 2018

This study was conducted to identify the factors influencing patient safety behavior and performance of infection control in nursing students. This study was a descriptive survey based on data collected from August 28, 2017, to September 22, 2017 from 174 third and fourth year nursing students at E university located in S city of Gyeonggi. The collected data were analyzed using the PASW 23.0 program to conduct an independent t-test, one-way ANOVA, post-hoc Scheffe's test, Pearson's correlation, and multiple regression. The average scores of patient safety behavior and performance of infection control were $4.00{\pm}0.55$ and $4.31{\pm}0.50$, respectively. Patient safety behavior and performance of infection control showed a strong positive correlation. Patient safety behavior was positively influenced by confidence levels of patient safety and awareness of the infection control, and the explanatory power of the model (R2)[ED highlight - should this be R2? If so, change throughout the paper.] was 55.1%. Predictors of the performance of infection control were patient safety knowledge, confidence levels regarding patient safety, and awareness of infection control, and the R2 was 68.1%. Common factors influencing patient safety behavior and infection control performance were patient safety confidence and development of effective clinical practicum education programs to increase confidence in patient safety and infection control.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.460-469
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• 2020

The purpose of this study was to examine the predictive factors for health promotion behaviors of older adults in rural areas. A theoretical substruction was constructed to test hypothetical models based on Pender's health promotion model. The data was collected from 199 older adults aged 65 years or older, who resided in G city, by using a structured questionnaire. The questionnaires contained items on individual characteristics, health literacy, self efficacy and health promoting behavior. The data was analyzed with a t-test, ANOVA, Pearson's correlation coefficients and hierarchical multiple regression analysis using SPSS 20.0 for Windows. The predictive factors for the health promotion behavior were the number of health information channels (β=.16, p=.031) and self efficacy (β=.53, p<.001). The total explanatory power of these factors was 30.8%. A nursing intervention plan for improving health promoting behaviors of older adults should be developed and applied, with a focus on self-efficacy and health information channels. Further longitudinal studies are needed to help confirm relevant measurement of the level of health promoting behaviors of older adults.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5715-5721
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• 2011

This research analyzed the cognitive factors affecting stroke patient's activity of daily living performance and suggests the approaches which can contribute to the effective activity of daily living performance in the rehabilitation treatment of stroke patients. In this study, Seoul Computerized NeuroCognitive Function Test (SCNT) and MBI have been performed for 21 patients under extensive rehabilitation treatments, hospitalized in the rehabilitation clinic of A hospital after being diagnosed as a stroke caused by cerebrovascular disorders. To assess the effectiveness of the cognitive factors which affect the stroke patient's activity of daily living performance, activity of daily living performance values were set as dependent variables and 10 cognitive factors were included in the model to carry out analysis of the multiple regression analysis. The results show that stroke patient's activity of daily living performance have statistically significant correlations with divided attention, motor control and selectivir attention. In addition, cognitive factors explained 69.8% of the stroke patient's activity of daily living performance. Consequently, if divided attention and motor control are considered as a focal point of training in the rehabilitation treatment of stroke patients, we can effectively promote the improvement of the activity of daily living performanceroutine activities.