• 대한수학회지
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• 제59권6호
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• pp.1171-1184
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• 2022

We study the real-analytic continuation of local real-analytic solutions to the Cauchy problems of quasi-linear partial differential equations of first order for a scalar function. By making use of the first integrals of the characteristic vector field and the implicit function theorem we determine the maximal domain of the analytic extension of a local solution as a single-valued function. We present some examples including the scalar conservation laws that admit global first integrals so that our method is applicable.

• Nonlinear Functional Analysis and Applications
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• 제28권1호
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• pp.237-249
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• 2023

In this paper, by means of the Schauder fixed point theorem and Arzela-Ascoli theorem, the existence and uniqueness of solutions for a class of not instantaneous impulsive problems of nonlinear fractional functional Volterra-Fredholm integro-differential equations are investigated. An example is given to illustrate the main results.

• Nonlinear Functional Analysis and Applications
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• 제28권3호
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• pp.851-863
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• 2023

We study the appropriate conditions for the findings of uniqueness and existence for a group of boundary value problems for impulsive Ψ-Caputo fractional nonlinear Volterra-Fredholm integro-differential equations (V-FIDEs) with symmetric boundary non-instantaneous conditions in this paper. The findings are based on the fixed point theorem of Krasnoselskii and the Banach contraction principle. Finally, the application is provided to validate our primary findings.

• Nutrition Research and Practice
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• 제9권1호
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• pp.87-91
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• 2015

BACKGROUND/OBJECTIVES: This research was conducted to compare lecture- and experience-based methods of nutritional education as well as provide fundamental data for developing an effective nutritional education program in elementary schools. SUBJECTS/METHODS: A total of 110 students in three elementary schools in Jeollanam-do were recruited and randomly distributed in lecture- and experience-based groups. The effects of education on students' dietary knowledge, dietary behaviors, and dietary habits were analyzed using a pre/post-test. RESULTS: Lecture- and experience-based methods did not significantly alter total scores for dietary knowledge in any group, although lecture-based method led to improvement for some detailed questions. In the experience-based group, subjects showed significant alteration of dietary behaviors, whereas lecture-based method showed alteration of dietary habits. CONCLUSIONS: These outcomes suggest that lecture- and experience-based methods led to differential improvement of students' dietary habits, behaviors, and knowledge. To obtain better nutritional education results, both lectures and experiential activities need to be considered.

• 보건교육건강증진학회지
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• 제21권1호
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• pp.197-216
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• 2004

The purpose of this study was to compare beliefs about social rule, differential peer association, perceived behavioral control, intention of smoking, and self efficacy for rejecting smoking among smokers, reformed smokers, and non smokers in adolescence. The subjects were 576 adolescents in middle and high school, living in K city. The data was collected through questionnaires from December 1st to 18th, 2002 was analyzed using descriptive statistics, x²-test, and ANOVA. 1) The general characteristics and characteristics related to smoking among smokers, reformed smokers, and non smokers in adolescence showed differences as follows： sex, mother's education, monthly allowance, thinking about teacher's smoking, feelings about the smoking scene, thinking about father's smoking, drinking, satisfaction of school, and sexual experience. 2) Belief about social rule, differential peer association, perceived behavioral control, intention of smoking, and self efficacy for rejecting smoking among the three groups showed differences as follows： smokers have a lower belief about social rule, lower perceived behavioral control, lower self-efficacy for rejecting smoking, but higher differential peer association and higher intention of smoking than those of reformed smokers and non smokers. We recommend the development of a nursing program for anti-smoking behavior including the research factors affecting attitudes of smoking adolescents.

• 정보교육학회논문지
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• 제20권5호
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• pp.527-534
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• 2016

본 연구는 소프트웨어에 대해 초등학생들이 가진 이미지를 의미분별법을 이용하여 분석하였다. 검사의 항목은 총 35쌍의 소프트웨어 이미지 형용사를 선정하여 요인분석을 통해 7개의 주요인으로 구분하고 초등학생을 대상으로 조사하였다. 성별 간 SW이미지를 분석한 결과 남학생보다는 여학생이 소프트웨어를 어렵고 복잡하게 여기며 느리고 갖고 싶지 않다는 인식을 보였다. 또한 소프트웨어에 대한 자기 인식의 분석 결과 소프트웨어에 대해 잘 안다고 인식할 경우 소프트웨어에 대한 긍정적인 용어를 선호하고 있었다. 학년간 분석에서 고학년이 될수록 소프트웨어를 어렵고 복잡하며 소프트웨어의 객관적인 특징에 대한 답변을 하였다. 본 연구를 통해 소프트웨어 교육이 정규교과로 안착되는데 필요한 방향을 안내하였다.

• Smart Structures and Systems
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• 제26권3호
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• pp.345-360
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• 2020

Modern swarm intelligence heuristic search methods are widely applied in the field of structural health monitoring due to their advantages of excellent global search capacity, loose requirement of initial guess and ease of computational implementation etc. To this end, a hybrid strategy is proposed based on butterfly optimization algorithm (BOA) and differential evolution (DE) with purpose of effective combination of their merits. In the proposed identification strategy, two improvements including mutation and crossover operations of DE, and dynamic adaptive operators are introduced into original BOA to reduce the risk to be trapped in local optimum and increase global search capability. The performance of the proposed algorithm, hybrid butterfly optimization and differential evolution algorithm (HBODEA) is evaluated by two numerical examples of a simply supported beam and a 37-bar truss structure, as well as an experimental test of 8-story shear-type steel frame structure in the laboratory. Compared with BOA and DE, the numerical and experimental results show that the proposed HBODEA is more robust to detect the reduction of stiffness with limited sensors and contaminated measurements. In addition, the effect of search space, two dynamic operators, population size on identification accuracy and efficiency of the proposed identification strategy are further investigated.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제18권2호
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• pp.79-92
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• 2004

This paper offers an analysis of how students reasoned with the dynamic parameter time to support their mathematical activity and deepen their understandings of mathematical concepts. This mathematical thinking occurred as they participated in a differential equations class before, during, and instruction on solutions to linear systems of differential equations. Students participated in the following identified mathematical practices related to parametric reasoning during this time period: reasoning simultaneously in a qualitative and quantitative manner, reasoning by moving from discrete to continuous imaging of time, and reasoning by imagining the motion. Examples of this reasoning are provided in this report. Implications of this research include the possibility that instructional activities can build on this reasoning to help students learn about the mathematics of change at the middle school, high school, and the university.

• 한국수학교육학회지시리즈A:수학교육
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• 제14권1호
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• pp.22-26
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• 1975

In this paper, we define a differential module and study its properties. In section 2, as for propositions, Ive research some properties, directsum, isomorphism of factorization, exact sequence of derived modules. And then as for theorem, I try to present the following statement, if the sequence of homomorphisms of differential modules is exact. Then the sequence of homomorphisms of Z(X) is exact, also the sequence of homomorphisms of Z(X) is exact. According to the theorem, as for Lemma, we consider commutative diagram between exact sequence of Z(X) and exact sequence of Z'(X) . As an immediate consequence of this theorem, we obtain the following result. If M is an arbitrary module and the sequence of homomorphisms of the modules Z(X) is exact, then the sequence of their tensor products with the trivial endomorphism is semi-exact.

• 공학교육연구
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• 제6권1호
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• pp.32-41
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• 2003

본 논문에서는 자바 애플릿을 이용하여 웹 기반의 미분방정식 학습용 컨텐츠를 개발하였다. 컴퓨터 분야의 컴포넌트 기반의 소프트웨어 개발기법을 도입하여, 사용하기에 단순하고 편리한 자바 빈즈 컴포넌트를 먼저 개발하고, 이를 활용하여 미분방정식 학습용 컨텐츠를 개발하였다. 개발된 컨텐츠는 높은 상호작용 기능을 가지고 있어서, 학습자가 흥미를 갖고 학습할 수 있고, 풀이 절차를 반복적으로 확인할 수 있으며, 복잡한 수학적 개념을 쉽게 이해할 수 있다.