• Structural Engineering and Mechanics
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• 제26권5호
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• pp.591-615
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• 2007

An improvement is introduced to solve the plane problems of linear elasticity by reciprocal theorem for orthotropic materials. This method gives an integral equation with complex kernels which will be solved numerically. An artificial boundary is defined to eliminate the singularities and also an algorithm is introduced to calculate multi-valued complex functions which belonged to the kernels of the integral equation. The chosen sample problem is a plate, having a circular or elliptical hole, stretched by the forces parallel to one of the principal directions of the material. Results are compatible with the solutions given by Lekhnitskii for an infinite plane. Five different orthotropic materials are considered. Stress distributions have been calculated inside and on the boundary. There is no boundary layer effect. For comparison, some sample problems are also solved by finite element method and to check the accuracy of the presented method, two sample problems are also solved for infinite plate.

• 한국조사연구학회:학술대회논문집
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• 한국조사연구학회 2006년도 추계학술대회 발표논문집
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• pp.67-83
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• 2006

In successive sampling on two occasions the problem of estimating a finite population quantile has been considered. The theory developed aims at providing the optimum estimates by combining (i) three double sampling estimators viz. ratio-type, product-type and regression-type, from the matched portion of the sample and (ii) a simple quantile based on a random sample from the unmatched portion of the sample on the second occasion. The approximate variance formulae of the suggested estimators have been obtained. Optimal matching fraction is discussed. A simulation study is carried out in order to compare the three estimators and direct estimator. It is found that the performance of the regression-type estimator is the best among all the estimators discussed here.

• Journal of the Korean Statistical Society
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• 제36권4호
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• pp.543-556
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• 2007

In successive sampling on two occasions the problem of estimating a finite population quantile has been considered. The theory developed aims at providing the optimum estimates by combining (i) three double sampling estimators viz. ratio-type, product-type and regression-type, from the matched portion of the sample and (ii) a simple quantile based on a random sample from the unmatched portion of the sample on the second occasion. The approximate variance formulae of the suggested estimators have been obtained. Optimal matching fraction is discussed. A simulation study is carried out in order to compare the three estimators and direct estimator. It is found that the performance of the regression-type estimator is the best among all the estimators discussed here.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.407-427
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• 2009

A fundamental solution for the transient, quasi-static, plane problems of linear viscoelasticity is introduced for a specific material. An integral equation has been found for any problem as a result of dynamic reciprocal identity which is written between this fundamental solution and the problem to be solved. The formulation is valid for the first, second and mixed boundary-value problems. This integral equation has been solved by BEM and algorithm of the BEM solution is explained on a sample, mixed boundary-value problem. The forms of time-displacement curves coincide with literature while time-surface traction curves being quite different in the results. The formulation does not have any singularity. Generalized functions and the integrals of them are used in a different form.

• 정보처리학회논문지B
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• 제13B권7호
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• pp.671-678
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• 2006

본 논문에서는 두 영상간의 대응관계로부터 퍼지 분류기법을 이용한 강건한 카메라 동작 추정 방법을 제안한다. 제안한 방법에서는 이상치가 존재할 때 정확한 카메라 동작을 추정하기 위하여 대표적인 강건 예측기법인 RANSAC 알고리즘을 사용한다. 그런데 RANSAC은 사전에 결정되는 이상치의 비율에 따라 정확도가 좌우되는 샘플링 문제점을 가지고 있다. 이러한 문제점을 개선하기 위해 샘플링 시에 퍼지 분류기법을 이용하여 전체 샘플을 좋은, 모호한, 나쁜 샘플로 분류한다. 그런 후에 좋은 데이터에 대해서만 샘플링을 수행함으로써 이상치 제거에 대한 정확도를 향상시킨다. 실험에서는 호모그래피 계산에 대한 성능을 비교함으로써 제안한 방법의 우수함을 보인다.

• Communications for Statistical Applications and Methods
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• 제8권3호
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• pp.719-729
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• 2001

Overlap Maximization is a sampling technique to reduce survey costs and costs associated with the survey. It was first studied by Keyfitz(1951). Ernst(1998) presented a remarkable procedure for maximizing the overlap when the sampling units can be selected for two identical stratified designs simultaneously, But the approach involves mimicking the behaviour of nonlinear function by linear function and so it is less direct, even though the stratification problem for the overlap corresponds directly to the linear programming problem. furthermore, it uses the controlled selection algorithm that repeatedly needs zero-restricted controlled roundings, which are solutions of capacitated transportation problems. In this paper we suggest a comparatively simple procedure to use linear programming in order to maximize the overlap. We show how this procedure can be implemented practically.

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.4173-4176
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• 2012

Background: Adolescent tobacco use is a major public health problem. However, there is little information about the impact of tobacco advertising and availability near schools on adolescent tobacco use in India. Methods: The various tobacco products and brands available in outlets within 100 meters of two high schools in an Indian town were identified. A stratified random sample of 172 participants from these two schools completed a questionnaire on tobacco use and socioeconomic status. Results: Eighteen outlets selling tobacco products were identified. In the two schools the current use of smoked and smokeless tobacco was 9.1% and 17.4% respectively. School location and low socio-economic status of adolescents were associated with tobacco awareness of advertisements (p=0.001) and the receipt of a free sample (p= 0.032). Advertisements on billboards, posters and the receipt of a free tobacco sample were significant factors (p=0.031, p=0.016, p=0.017 respectively) in current tobacco use. Conclusion: In this study a significant proportion of adolescents used tobacco. Tobacco-promotion activities (advertising, the receipt of a free sample), school location and economic status were found to be associated with adolescent tobacco initiation. The local environment should be included in the prevention of adolescent tobacco initiation.

• Structural Engineering and Mechanics
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• 제4권2호
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• pp.191-202
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• 1996

This paper presents a construction of adaptive boundary element for the problem with mixed boundary conditions such as heat transfer between heated body surface and surrounding medium. The scheme is based on the sample point error analysis and on the extended error indicator, proposed earlier by the authors for the potential and elastostatic problems, and extended successfully to multidomain and thermoelastic analyses. Since the field variable is connected with its derivative on the boundary, their errors are also interconnected by the specified condition. The extended error indicator on each boundary element is modified to meet with the situation. Two numerical examples are shown to indicate the differences due to the prescribed boundary conditions.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제6권2호
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• pp.171-182
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• 2002

Students approach mathematical problem solving in fundamentally different ways, particularly problems requiring conceptual understanding and complicated strategies such as mathematical word problems. The main objective of this study is to compare students' performance with different cognitive styles (Field-dependent vs. Field-independent) on mathematics problem solving, particularly, in word problems. A sample of 180 school girls (13-years-old) were tested on the Witkin's cognitive style (Group Embedded Figures Test) and two mathematics exams. Results obtained support the hypothesis that students with field-independent cognitive style achieved much better results than Field-dependent ones in word problems. The implications of these results on teaching and setting problems emphasizes that word problems and cognitive predictor variables (Field-dependent/Field- independent) could be challenging and rather distinctive factors on the part of school learners.

• Journal of the Korean Statistical Society
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• 제30권4호
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• pp.679-691
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• 2001

Two truncated sequential tests are developed for the two-sample scale problem based on the usual Wilcoxon rank-sum statistic for two different dispersion indices - absolute median deviations, when the medians of the two populations X and Y are equal or known and sums of squared mean deviations, when the medians are either unknown or unequal. The first test is briefly called SWAMD test and the second SWSMD test. For the SWAMD test, the percentile points for both the one-sided and two-sided alternatives, (equation omitted) have been found by Wiener approximation and their values computed for a range of values of a and N; analytical expression for the power function has been derived through Wiener process and its performance studied for various sequential designs for exponential distribution. This test has been illustrated by a numerical example. All the results of the SWAMD test, being directly applicable to the SWSMD test, are not dealt with separately Both the tests are compared and their suitable applications indicated.