• Journal of The Korean Association For Science Education
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• v.21 no.4
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• pp.710-724
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• 2001

The purpose of this study was to regression analysis for variables on effect of development of scientific thinking. The subjects sampled in this study was 117 5th grade students, 131 8th grade students, and 127 11th grade students. The students were administered test of 10 questionnaires. The GALT(group assessment of logical thinking), FIT(figured intersection test), and GEFT(group embedded figural intersection test) were used which developed previous researchers. And other questionnaires were modified. The result of this study showed that cognitive variables, psychological variables, home variables and learning environment variables made effects on scientific thinking. Cognitive variables, psychological variables, home variables, and learning environment variables explained 60%, 10%, 5% and 10% to scientific thinking. All of those variables explained around 86%. Overall, 5th, 8th and 11th grade models were similar but with some differences in the effects of contextual variables with in the models.

• Communications of the Korean Mathematical Society
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• v.22 no.3
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• pp.441-452
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• 2007

The exact distributions of X + Y, XY and X/(X + Y) are derived when X and Y are independent generalized Planck random variables.

• Bulletin of the Korean Mathematical Society
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• v.45 no.2
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• pp.339-353
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• 2008

The distributions of products and ratios of random variables are of interest in many areas of the sciences. In this paper, the exact distributions of the product |XY| and the ratio |X/Y| are derived when X and Y are independent Pearson type VII random variables.

• Korean Journal of Logic
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• v.22 no.1
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• pp.183-209
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• 2019

In this paper, I first examine Reiss'(2005) arguments for the causal instrumental variable. Second, I argue that the conditions for causal transitivity I consider meet what the causal instrumental variables and the interveners of the manipulation theory of causation are intended to hold. Reiss shows that two conditions for instrumental variables are not sufficient for causal significance of independent variables for dependent variables. Reiss articulates and reformulates the conditions for instrumental variables in terms of the conditions on causality, while naming his instrumental variables as causal instrumental variables. Reiss argues that the causal instrumental variables are similar to the interveners of the manipulation, or intervention theory of causation. He further argues that the causal instrumental variables do a better job the interveners do. I argue that the conditions for causal transitivity I consider meet the goal the conditions for the causal instrumental variables and the conditions for the interveners both are intended to achieve.

• Journal of the Korean housing association
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• v.25 no.6
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• pp.39-47
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• 2014

The background of this study is to examine the structure of housing price of which characteristics are not equal but hierarchical in the apartment complexes. So, the purpose of this study is to analyze the influences of apartment complex characteristics on the housing price within the same regional boundary by HLM. The data used as dependent variables were the market prices of 938 units from 29 apartment complexes by stratified sampling. The 2nd level independent variables is the Housing complex characteristics which are composed of the housing complex & locational variables and the 1st level independent variables are the unit characteristics. The results are as follows. First, the first model shows that the 2nd level variables explains 68% of the housing prices. Second, the influential variables of the 1st level unit variable are 'dwelling exclusive area', 'floor of dwelling' and 'direction of dwelling'. Third, the influential variables of the housing complex variables in the 2nd level are 'lot area', 'the building-to-land ratio', 'the number of unit', 'the number of parking lots per unit', 'Green space area' and 'open space area per unit'. The last, the influential variables of the housing locational variables in the 2nd level are 'distance to subway and park' and the number of school and park within a radius of 1km.

• Journal of Agricultural Extension & Community Development
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• v.8 no.2
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• pp.201-208
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• 2001

The purpose of this study was to review the current studies on community attachment and its related variables to suggest directions for community attachment studies in Korea. Specific objectives of the study were to search the current studies on community attachment, to search for the significant variables related to community attachment, and to draw implications for community development in Korea. The major findings of the study were as follows; 1) Current studies on community attachment used individual characteristic variables such as length of residence in the community, age, size of population and density as major independent variables. 2) Studies on community attachment used community participation, social and cultural environment as major dependent variables, however, both independent variables and dependent variables were used interchangeably in many cases. 3) Recent studied on community attachment employed community economic and cultural variables, however, studies on community attachment in Korea was relatively limited in terms of quantity as well as quality. 4) Further research on community attachment should be conducted by utilizing various independent and dependent variables in various communities to increase the community attachment in rural and urban communities to further strengthen community development in Korea.

• Health Policy and Management
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• v.4 no.2
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• pp.58-76
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• 1994

In order to study factors affecting the use of the ambulatory physician services. Andersen's model for health utilization was modified by adding the health behavior component and examined with three different approaches. Three different approaches were the multiople regression model, logistic regression model, and LISREL model. For multiple regression, dependent variable was reported illness-related visits to a physician during past one year and independent variables are variaous variables measuring predisposing factor, enabling factor, need factor and health behavior. For the logistic regression, dependent variable was visit or no-visit to a physician during past one year and independent variables were same as the multiple regression analysis. For the LISREL, five endogenous variables of health utiliztion, predisposing factor, enabling factor, need factor, and health behavior and 20 exogeneous variables which measures five endogenous variables were used. According to the multiple regression analysis, chronic illness, health status, perceived health status of the need factor; residence, sex, age, marital status, education of the predisposing factor ; health insurance, usual source for medical care of enabling factor were the siginificant exploratory variables for the health utilization. Out of the logistic regression analysis, health status, chronic illness, residence, marital status, education, drinking, use of health aid were found to be significant exploratory variables. From LISREL, need factor affect utilization most following by predisposing factor, enabling factor and health behavior. For LISREL model, age, education, and residence for predisposing factor; health status, chronic illess, and perceived health status for need factor; medical insurance for enabling factor; and doing any kind of health behavior for the health behavior were found as the significant observed variables for each theoretical variables.

• Journal of The Korean Association For Science Education
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• v.19 no.3
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• pp.471-478
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• 1999

In this study, the relationships among learners' cognitive variables, motivational variables, and conceptual understandings in learning with analogy were investigated. The instruments regarding analogical reasoning ability, field dependence-independence, mental capacity, and logical thinking ability were administered. Some subtests (self-efficacy, expectancy, self-concept of ability, and value) of the Patterns of Adaptive Learning Survey were administered. After students learned with a worksheet that included analogy, a conception test regarding 'stoichiometry that included limiting reagent' was also administered. It was found that learners' conceptual understandings were significantly correlated with the logical thinking ability and the field dependence-independence among the cognitive variables, and the self-efficacy and the self-concept of ability among the motivational variables. The multiple regression analysis of the cognitive variables on conceptual understandings revealed that the logical thinking ability was the most significant predictor. The field dependence-independence also had predictive power. In the analysis of the motivational variables, the self concept of ability was the only significant predictor.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2084-2093
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• 2022

Probabilistic safety assessment is widely used to quantify the risks of nuclear power plants and their uncertainties. When the lognormal distribution describes the uncertainties of basic events, the uncertainty of the top event in a fault tree is approximated with the sum of lognormal random variables after minimal cutsets are obtained, and rare-event approximation is applied. As handling complicated analytic expressions for the sum of lognormal random variables is challenging, several approximation methods, especially Monte Carlo simulation, are widely used in practice for uncertainty analysis. In this study, a theoretical approach for analyzing the sum of lognormal random variables using an efficient numerical integration method is proposed for uncertainty analysis in probability safety assessments. The change of variables from correlated random variables with a complicated region of integration to independent random variables with a unit hypercube region of integration is applied to obtain an efficient numerical integration. The theoretical advantages of the proposed method over other approximation methods are shown through a benchmark problem. The proposed method provides an accurate and efficient approach to calculate the uncertainty of the top event in probabilistic safety assessment when the uncertainties of basic events are described with lognormal random variables.

• Bulletin of the Korean Mathematical Society
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• v.35 no.4
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• pp.709-718
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• 1998

In this paper we obtain strong laws of large numbers for 2-dimensional arrays of random variables which are either pairwise positive quadrant dependent or associated. Our results imply extensions of Etemadi`s strong laws of large numbers for nonnegative random variables to the 2-dimensional case.