• 한국과학교육학회지
• /
• 제21권4호
• /
• pp.710-724
• /
• 2001

본 연구는 과학적 사고력에 영향을 미치는 변인의 설명력을 분석하는데 그 기본 목적이 있다. 이를 위하여 5학년,8학년,11학년 학생 총 375명을 대상으로 과학적 사고력에 영향을 줄 것으로 가정한 변인을 조사하여 분석하였다. 본 연구의 결과, 과학적 사고력에 대한 학습자의 인지적 변인의 설명력은 약 60%, 심리적 변인 10%, 가정 변인 5%, 학습환경 변인 10%였다. 이들 변인이 과학적 사고력을 최대 85% 설명하였다. 학년에 따라서 과학적 사고력에 직접적인 영향을 주는 것은 학습자의 인지적 변인, 심리적 변인, 가정 변인, 학습환경 변인이었다. 가정 변인과 학습환경 변인은 과학적 사고력에 간접적인 영향을 주었다. 또한, 학교급에 따라서 그 설명력은 차이가 있었다. 따라서 학교급에 따라 과학적 사고력을 향상시키기 위한 전략에 차별화가 필요하다.

• 대한수학회논문집
• /
• 제22권3호
• /
• pp.441-452
• /
• 2007

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

• 대한수학회보
• /
• 제45권2호
• /
• pp.339-353
• /
• 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.

• 논리연구
• /
• 제22권1호
• /
• pp.183-209
• /
• 2019

이 글에서 필자는 회귀 분석(regression)에 이용되는 도구 변수(instrumental variables)에 대하여 인과 구조 모형의 관점에서 제시된 새로운 이론을 검토하고 평가한다. 도구 변수는 회귀분석에서 결과로 가정하는 종속 변수에 대해 원인으로 가정하는 독립 변수가 갖는 원인 효과를 올바르게 평가하기 위해 고안된 것이다. 도구 변수는 두 가지 조건을 충족해야 한다. 첫째, 도구 변수는 독립 변수와 상관관계를 가져야 한다. 둘째, 도구 변수는 오차항과 상관관계를 가져서는 안 된다. 라이스(Reiss 2005)는 기존의 두 조건만으로는 도구 변수로 독립 변수의 원인 효과를 온전히 드러낼 수 없다고 본다. 라이스는 도구 변수가 이들 두 조건을 충족하여도 독립 변수가 종속 변수에 원인 효과를 갖지 않는 경우가 가능함을 보여준다. 라이스는 기존의 조건에 인과의 특성에 관한 조건들을 도입하고 이를 토대로 인과 도구변수 조건을 다시 제시한다. 다른 한편으로, 라이스는 도구 변수가 인과에 대한 조종 이론의 조종자(개입, 간섭)와 유사한 역할을 한다고 본다. 라이스는 도구 변수와 조종자(개입, 간섭)의 유사성과 차이성을 제시하고 인과 도구변수의 조건이 조종자의 조건보다 상대적으로 방법론적 수월성을 갖는다고 주장한다. 필자는 라이스의 주장들을 검토하고, 도구 변수를 위한 새로운 인과 조건이 필요한지를, 그리고 방법론적 수월성이 있는지를 평가하겠다. 필자가 고려하는 인과의 이행성을 위한 조건만으로도 인과 도구 변수와 조종자의 조건의 목표를 충족할 수 있는지를 보겠다.

• 한국주거학회논문집
• /
• 제25권6호
• /
• pp.39-47
• /
• 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.

• 농촌지도와개발
• /
• 제8권2호
• /
• pp.201-208
• /
• 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.

• 보건행정학회지
• /
• 제4권2호
• /
• pp.58-76
• /
• 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.

• 한국과학교육학회지
• /
• 제19권3호
• /
• pp.471-478
• /
• 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
• /
• 제54권6호
• /
• pp.2084-2093
• /
• 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.

• 대한수학회보
• /
• 제35권4호
• /
• pp.709-718
• /
• 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.