• 제어로봇시스템학회논문지
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• 제5권5호
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• pp.521-528
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• 1999

The nth-order, scalar, linear time-varying (LTV) systems can be dealt with operators on a differential ring. Using this differential algebraic structure and a classical result on differential operator factorizaitons developed by Floquet, a novel eigenstructure(eigenvalues, eigenvectors) concepts for linear time0varying systems are proposed. In this paper, Necessary and sufficient conditions for the existence of well-defined(free of finite-time singularities) SD- and PD- spectra for SPDOs with complex- and real-valued coefficients are also presented. Three numerical examples are presented to illustrate the proposed concepts.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.468-470
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• 1998

We have studied system identification model reduction method, optimal control by orthogonal functions. This paper presents the easy method that solves algebra equations instead of differential equations using Walsh, Haar, Block pulse function of orthogonal functions in state equation. The proposed algorithm is verified through some examples.

• Kyungpook Mathematical Journal
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• 제46권4호
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• pp.527-541
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• 2006

In this paper, an existence theorem for a nonlinear two point boundary value problem of second order differential equations in Banach algebras is proved using a nonlinear alternative based on Leray-Schauder alternative.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제12권4호
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• pp.283-291
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• 2008

The extension to a wide population of secondary education in many advanced countries seems to have led to a weakening of the mathematics curriculum. In response, many students have been classified as "gifted" so that they can access a stronger program. Apart from the difficulties that might arise in actually determining which students are gifted (Is it always clear what the term means?), there are dangers inherent in programs that might be devised even for those that are truly talented. Sometimes students are moved ahead to more advanced mathematics. Elementary students might be taught algebra or even subjects like trigonometry and vectors, and secondary students might be taught calculus, differential equations and linear algebra. It is my experience over thirty-five years of contact with bright students that acceleration to higher level mathematics is often not a good idea. In this paper, I will articulate some of the factors that have led me to this opinion and suggest alternatives. First, I would like to emphasize that in matters of education, almost every statement that can be made to admit counterexamples; my opinion on acceleration is no exception. Occasionally, a young Gauss or Euler walks in the door, and one has no choice but to offer the maximum encouragement and allow the student to go to the limit of his capabilities. A young genius can demonstrate an incredible amount of mathematical insight, maturity and mastery of technique. A classical example is probably the teen-age Euler, who in the 1720s was allowed regular audiences with Jean Bernoulli, the foremost mathematician of his day.

• Journal of Computing Science and Engineering
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• 제11권4호
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• pp.130-141
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• 2017

Feature selection is one of the most challenging problems of pattern recognition and data mining. In this paper, a feature selection algorithm based on an improved version of binary differential evolution is proposed. The method simultaneously optimizes two feature selection criteria, namely, set approximation accuracy of rough set theory and relational algebra based derived score, in order to select the most relevant feature subset from an entire feature set. Superiority of the proposed method over other state-of-the-art methods is confirmed by experimental results, which is conducted over seven publicly available benchmark datasets of different characteristics such as a low number of objects with a high number of features, and a high number of objects with a low number of features.

• Nonlinear Functional Analysis and Applications
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• 제26권2호
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• pp.225-236
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• 2021

In this paper, we determine position vector of a line of curvature of a regular surface which is relatively normal-slant helix, with respect to Darboux frame. Then, a vector differential equation is established by means Darboux formulas, in the case of the geodesic torsion is vanishes. In terms of solution, we determine the parametric representation of a line of curvature which is relatively normal-slant helix, with respect to standard frame in Euclidean 3-space. Thereafter, we apply this result to find the position vector of a line of curvature which is isophote curve.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제31권3호
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• pp.241-255
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• 2017

스마트 교육 환경과 4차 산업 혁명 시대를 맞이하여 편리한 기능을 갖는 다양한 테크놀로지들을 활용하는 새로운 차원의 디지털 수학 교과서가 필요하게 되었다. 한국의 경우 초 중등 수학 교육에서는 여러 다양한 시도가 있었으나 대학 수학교육의 경우 디지털 수학 교과서 관련 연구는 미비하였다. 본 논문에서는 선형대수학을 중심으로 디지털 콘텐츠와 대화형 실습실을 활용하는 디지털 교과서를 소개한다. 본 교과서는 본 연구진이 직접 개발하여 누구나 http://matrix.skku.ac.kr/LA-K에서 다운로드 받을 수 있도록 제공하였으며, 기존의 종이 교과서(서책형)를 단순히 pdf 형태의 파일로 변환하여 애니메이션이나 참고자료 등을 추가한 수준에서 벗어나 전자책, 웹 콘텐츠, 강의 동영상, 대화형 실습실을 포함한다. 본 선형대수학 디지털 교과서는 학생들이 어떠한 모바일 기기에서든 시간과 장소의 제약 없이 자유롭게 사용할 수 있으며, 계산, 코딩 및 타이핑 과정에서 절약된 시간을 수학 개념을 더 깊이 이해하는데 사용할 수 있다. 코드를 포함한 대화형 실습실 및 동영상 강의를 탑재한 최초의 수학 디지털 교과서로 평가되는 본 연구의 결과물은 차세대 디지털 교과서의 주요 모델 중 하나가 될 것으로 판단된다.

• 한국콘텐츠학회논문지
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• 제8권5호
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• pp.276-286
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• 2008

본 논문에서는 컴퓨터 대수 시스템을 기반으로 하는 웹 저작 환경과 베이지언 추론망을 적용한 학습자 진단 환경이 포함된 이공계 수학용 적응적 이러닝 시스템 개발에 대하여 소개하였다. 본 시스템을 활용하면 교수자는 컴퓨터 대수 시스템을 수식처리 엔진으로 하며 웹을 인터페이스로 하는 이공계 수학용 웹 콘텐츠를 쉽게 생성할 수 있다. 구체적으로 선형대수, 미분방정식 및 이산수학의 영역에서 콘텐츠 개발의 예를 소개하였다. 또한 학습자의 지식 영역별 수준을 조건부 확률을 이용한 통계적 추론에 의해 진단하여 그 결과에 따라 피드백을 생성하는 적응적 이러닝 웹 콘텐츠를 만들 수 있다. 본 시스템을 사용하여 개발한 이공계 수학용 웹 콘텐츠를 평가하기 위하여 그 결과물을 대학 강의에 적용하였고, 설문지 조사를 통하여 콘텐츠 사용에 대한 학습자의 반응을 평가하였다.

• Korean Journal of Mathematics
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• 제6권2호
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• pp.313-318
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• 1998

In this paper we prove two independent theorems concerning formality of a nilmanifold and a differential graded algebra using the well-known theorem of Deligne-Griffiths-Morgan-Sullivan. We first give a rational homotopy theoretic proof to the statement that a nilmanifold is formal if and only if it is a torus. And then we study some conditions with which formality of one dga implies formality of the other in an extension of dga's.

• Korean Journal of Mathematics
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• 제22권1호
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• pp.207-216
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• 2014

The manifold $^*g-ESX_n$ is a generalized n-dimensional Riemannian manifold on which the differential geometric structure is imposed by the unified field tensor $^*g^{{\lambda}{\nu}}$ through the ES-connection which is both Einstein and semi-symmetric. The purpose of the present paper is to study the algebraic geometric structures of 3-dimensional $^*g-ESX_3$. Particularly, in 3-dimensional $^*g-ESX_3$, we derive a new set of powerful recurrence relations in the first class.