• Journal of Digital Convergence
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• v.11 no.9
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• pp.103-111
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• 2013

As the demand-oriented management has been getting important in Supply Chain Management (SCM), various forecasting methods have been suggested including regression analyses. However, dependency structures among variables have been captured by a correlation coefficient, only. It results in inaccurate demand predictions. This paper suggests a new and effective forecasting modeling framework using student's t-copula function. In order to show overall modeling procedures framework, heavy tail typed numerical data and its copula estimations are provided. The suggested methodology can contribute to decrease the bullwhip effect and to stabilize volatile environment in a supply chain network.

• Journal of Korean Home Economics Education Association
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• v.10 no.1
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• pp.95-106
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• 1998

The purposes of this study is to find middle school student's application of Home Economics course and its related variables. The samples are 323 middles school students in Kangneung. For the statistics analysis of this study, frequency, mean, Cronbach's a coefficient, ANOVQ, t-test, Pearson'correlation and multiple regression were calculated. The results of this study are summarized as follows ; 1. It is appeared that middle school student's application of Home Economics course are the food, human development and family relationship family, resources management and the consuming, the clothing. 2. Variables that affect middle school student's application of Home Economics course are the vocation of father, way of learning about home life skill, agreement with educational goal of Home Economic, evaluation of Home Economic teacher, evaluation of education field, participation in class of Home Economic and needs for Home Economics. 3. The explanation degree of these seven variables is 27.7% and needs for Home Economics is the most domineering variables.

• The Journal of Korean Society for School & Community Health Education
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• v.10 no.1
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• pp.47-60
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• 2009

Purpose: The purpose of this study was to determine the effects of infection control education, knowledge, attitude and self-confidence of student nurses, regarding nosocomial infection control. Method: This was a nonequivalent control group nonsychronized design. The participants were 83 student nurses who were conveniently assigned to the experimental or a control group. The data were collected from March 5 to June 11, 2008 and analyzed based on Fisher's exact test and t-test. Result: The 1st hypothesis, "Posttest nosocomial infection control knowledge scores for the experimental group will be higher than scores for the control group" was supported (t=2.057, p=.043). The 2nd hypothesis, "Posttest nosocomial infection control attitude scores for the experimental group will be higher than those for the control group" was not statistically significant (t=.466, p=.643), The 3rd hypothesis, "Posttest nosocomial infection control self-confidence scores for the experimental group will be higher than those for the control group" was not statistically significant (t=2.290 p=.025). Conclusion: This infection control education was effective in increasing the levels of knowledge and self-confidence for student nurses regarding nosocomial infection control.

• Journal of The Korean Association For Science Education
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• v.17 no.4
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• pp.383-393
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• 1997

In order to study the effect of student's conceptions about force and motion into the graph construction in kinematics in college physics course, the tasks of constructing the qualitative graph in the similar problem context used in force conception was asked to the first 74 and third 97 student teacher in teachers' university. The frequencies analysis showed that student teachers had the naive conceptions that the throwing force was still acted to a upwarding ball. They also had the popular Aristotelian views about motion. These naive conceptions coexisted with the scientific conception about gravitational force. In a simple pendulum problem no one had the correct acceleration concepts which varies the direction in swing. This result suggest that student teacher had more difficulties in a acceleration problem than in a velocity problem In v-t and a-t graph construction tasks, the number of categories of a-t graphs were more than that of v-t graphs. There were many graph errors in a sign of velocity and acceleration. The acceleration conceptions without the relations of changes in velocity made the kinematics graphs more various shapes. The force and motion conceptions influenced the ability to construct the kinematics graphs.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.2
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• pp.1-11
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• 2020

This study was carried out to verify how much instructor's communication skill affects the student pilot's study motivation and satisfaction. The instructor's communication styles are classified into 3 groups by pre-analysis. Three types are cooperative type, control type and professional type. Intellectual cause, performance proficiency cause, social cause and stimulation avoidance cause are extracted and analyzed for the cause of study motivation. Cooperative and control type affected all of 4 factors of student's study motivation by influence analysis. Intellectual cause affected control and cooperative type positively, especially more to cooperative type. Performance proficiency cause also had positive influence to control and cooperative type. Stimulation avoidance cause didn't appear to affect all sub-classified 4 factors of instructor's communication type. Influence analysis of student's study satisfaction from instructor's communication style showed that independent variable affected all sub factors positively. Degree of positive influence affected the control type the most, cooperative type was the 2nd, and professional type was the 3rd.

• Korean Journal of Human Ecology
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• v.24 no.2
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• pp.205-218
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• 2015

By examining variables affecting university student's perceptions of marriage, this study aimed to better understand how to promote positive perceptions of marriage among university students. The study sample consisted of 488 university students and their parents in Incheon and Gyeonggi, Korea. For data analysis, t-test, correlation analysis, and hierarchical regression analysis were performed. First, results showed that individual growth, emotional stability, and overall perceptions of marriage varied by gender. And results showed that individual growth, institutional necessity, and overall perceptions of marriage varied by grade. Second, higher levels of perceptions of marriage among university students were significantly correlated with greater university student's identity, better parent's marital relationship. Third, the personal relations was most influential variable on university student's perceptions of marriage, followed by the parent's conflict and authority the mother's duties, followed by the target orientating, gender and grade. Overall, results suggest that parent's marital relationship is important for promotion of positive perceptions of marriage among university students. Also, systematic analysis of university student's identity and programs to address such problems are needed.

• Journal of the Korean Statistical Society
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• v.33 no.4
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• pp.411-433
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• 2004

The shrinkage preliminary test ridge regression estimators (SPTRRE) based on Wald (W), Likelihood Ratio (LR) and Lagrangian Multiplier (LM) tests for estimating the regression parameters of the multiple linear regression model with multivariate Student's t error distribution are considered in this paper. The quadratic biases and risks of the proposed estimators are compared under both null and alternative hypotheses. It is observed that there is conflict among the three estimators with respect to their risks because of certain inequalities that exist among the test statistics. In the neighborhood of the restriction, the SPTRRE based on LM test has the smallest risk followed by the estimators based on LR and W tests. However, the SPTRRE based on W test performs the best followed by the LR and LM based estimators when the parameters move away from the subspace of the restrictions. Some tables for the maximum and minimum guaranteed efficiency of the proposed estimators have been given, which allow us to determine the optimum level of significance corresponding to the optimum estimator among proposed estimators. It is evident that in the choice of the smallest significance level to yield the best estimator the SPTRRE based on Wald test dominates the other two estimators.

• ETRI Journal
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• v.39 no.5
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• pp.662-671
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• 2017

Coronary artery disease (CAD) is a major cause of death in the world. As a non-invasive imaging modality, computed tomography angiography (CTA) is now usually used in clinical practice for CAD diagnosis. Precise quantification of coronary stenosis is of great interest for diagnosis and treatment planning. In this paper, a novel cluster method based on a Modified Student's t-Mixture Model is applied to separate the region of vessel lumen from other tissues. Then, the area of the vessel lumen in each slice is computed and the estimated value of it is fitted with a curve. Finally, the location and the level of the most stenoses are captured by comparing the calculated and fitted areas of the vessel. The proposed method has been applied to 17 clinical CTA datasets and the results have been compared with reference standard degrees of stenosis defined by an expert. The results of the experiment indicate that the proposed method can accurately quantify the stenosis of the coronary artery in CTA.

• The Korean Journal of Financial Studies
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• v.11 no.1
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• pp.157-176
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• 2005

본 연구는 KOSPI자산 포트폴리오에 대한 VaR를 다양한 ARCH류 모형을 사용하여 추정하고 이들의 예측능력을 평가하였다. 활용된 모형은 우선 기본적인 GARCH(1,1)모형과 레버리지 효과를 감안한 TGARCH모형, 다양한 ARCH모형을 포괄할 수 있는 PGARCH모형, 변동성의 영속성을 고려한 IGARCH모형이 포함되었다. 모형 상호간의 성과비교에 추가하여 ARCH류 모형에서 수익률예측오차의 분포에 따라서 VaR의 예측성과가 얼마나 차이가 발생하는가를 확인하기 위하여 정규분포와 Student-t분포의 성과를 비교하였다. 마지막으로 VaR 추정시에 조건부평균을 무시하는 관례가 어느정도 타당성이 있는지를 확인하기 위하여 1시차 자기회귀과정에 입각한 조건부 평균을 감안한 결과를 검토하였다. ARCH류 모형에서 모형 설명력은 보다 정교한 모형인 TGARCH모형이나 PGARCH모형이 우월하게 나타났지만, VaR의 예측능력 우월성으로 이어지지는 않았다. Student-t분포를 가정한 경우 VaR모형 사후검증성과는 정규분포를 가정한 경우보다 모든 신뢰수준에서 개선되었으며, 조건부평균의 제거는 Student-t분포 가정하에서는 적합하지 않은 것으로 나타났다. ARCH류 모형에서 가장 단순한 형태인 IGARCH모형의 예측성과가 다른 모형들에 비하여 뒤떨어지지 않으며, 더욱 제약된 형태인 RiskMetrics의 EWMA모형이 사후검증에서 우수한 성과를 보여 단순한 모형의 유용성을 확인시켜주고 있다.

• Human Ecology Research
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• v.52 no.1
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• pp.63-73
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• 2014

The purpose of this study is to investigate early childhood student teachers' practicum anxiety on the basis of the teacher's image and self-efficacy during their practicum. The participants of this study were 499 student teachers who were enrolled in the department of early childhood education in a college or a university and had completed the practicum in Daejeon metropolitan city or the Chungcheong area. The instruments for this study were the Teacher's Image Scale, Practicum Anxiety Scale, Self-efficacy Scale, and a questionnaire for socio-demographic variables. The collected data were analyzed by using a t -test, F test, Pearson's partial correlation, and multiple regression with SPSS software (version 20.0). The results were as follows: First, the student teachers expressed higher practicum anxiety in a provincial area than in metropolitan city, and their self-efficacy was higher in public kindergarten than in private kindergarten. Further, the highest level of the teacher's image was obtained in the case of student teachers who enrolled in a 2- or 3-year college program and completed the practicum in the metropolitan city. Second, there was a significant negative correlation between the sum of student teachers' practicum anxiety and their professional skills of teacher's image as well as significant correlations between the sum of student teachers' practicum anxiety and their self-efficacy, except self-control efficacy. Finally, the student teachers' practicum anxiety was found to be 17.5%-24.4% and was explained the most by the confidence of self-efficacy.