• 대한수학회지
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• 제54권2호
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• pp.399-415
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• 2017

Given a topological space X and a non-negative integer k, we study the self-homotopy equivalences of X that do not change maps from X to n-sphere $S^n$ homotopically by the composition for all $n{\geq}k$. We denote by ${\varepsilon}^{\sharp}_k(X)$ the set of all homotopy classes of such self-homotopy equivalences. This set is a dual concept of ${\varepsilon}^{\sharp}_k(X)$, which has been studied by several authors. We prove that if X is a finite CW complex, there are at most a finite number of distinguishing homotopy classes ${\varepsilon}^{\sharp}_k(X)$, whereas ${\varepsilon}^{\sharp}_k(X)$ may not be finite. Moreover, we obtain concrete computations of ${\varepsilon}^{\sharp}_k(X)$ to show that the cardinal of ${\varepsilon}^{\sharp}_k(X)$ is finite when X is either a Moore space or co-Moore space by using the self-closeness numbers.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제34권3호
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• pp.325-354
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• 2020

수학 학업성취도에 영향을 미치는 요인들은 매우 다양하며, 그 요인들이 미치는 영향 또한 복합적으로 일어난다. 수학 학업성취도에 영향을 미치는 요인들은 끊임없이 변화하고 발전하기 때문에 학습자들의 성장을 예측하고 분석하는 종단연구가 필요하다. 본 연구는 서울교육종단연구의 2013년도(중학교 1학년)부터 2017년(고등학교 2학년)까지의 종단자료를 활용하여 내적요인(자아개념, 자기통제, 삶의 만족에 대한 자기평가), 외적요인(학교풍토, 자녀에 대한 보호자의 관심, 보호자의 학습조력)의 변화패턴을 알아보고 내·외적요인이 수학 학업성취도에 어떠한 영향을 미치는지 살펴보았다. 수학 학업성취도를 분석한 결과, 중학교 1학년부터 중학교 2학년까지의 수학 학업성취도는 변화가 없는 것으로 나타났으며, 중학교 2학년부터 고등학교 1학년까지는 꾸준히 증가하다가 고등학교 2학년 때는 소폭 하향하는 것으로 나타났다. 내적요인인 자아개념과 자기통제는 중학교 1학년부터 중학교 2학년까지는 소폭 떨어지다가 고등학교 1학년까지는 소폭 증가하고 고등학교 2학년에는 소폭 떨어지는 것으로 나타났으며, 삶의 만족에 대한 자기평가는 중학교 1학년부터 고등학교 2학년까지의 기간 동안 소폭 떨어지는 것으로 나타났다. 외적요인 중 학교풍토는 중학교 1학년부터 중학교 2학년까지는 소폭 떨어지는 것으로 나타났으며, 고등학교 1학년까지는 증가하다가 고등학교 2학년에는 그 값이 유지되는 것으로 나타났다. 자녀에 대한 보호자의 관심은 중학교 1학년 때의 값이 고등학교 2학년까지 유지되는 것으로 나타났으며, 보호자의 학습조력은 중학교 1학년부터 지속적으로 감소하는 것으로 나타났다. 수학 학업성취도에 대한 영향을 알아보기 위해 임의 기울기 모델(Random Slope Model)을 시행한 결과 내적요인인 자아개념 및 자기통제, 그리고 외적요인인 학교풍토가 수학 학업성취도의 변화에 영향을 미치는 것으로 나타났다.

• East Asian mathematical journal
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• 제24권2호
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• pp.145-149
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• 2008

From the notion of bi-ideals in near-rings, various generalizations of regularity conditions have been studied. In this paper, we generalize further the notion of bi-ideals and introduce the notion of weak bi-ideals in near-rings and obtain some characterizations using this concept in left self distributive near-rings.

• Journal of applied mathematics & informatics
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• 제29권3_4호
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• pp.1027-1035
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• 2011

In this paper, we introduce the concept of generalized weak q-contractivity for multivalued maps defined on quasi-metric spaces. A new fixed point theorem for these maps is established. The convergene of iterate schem of the form $x_n+1\;{\in}\;Fx_n$ is investigated. And a new periodic point theorem for weakly q-contractive self maps of quasi-metric spaces is proved.

• Nonlinear Functional Analysis and Applications
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• 제28권1호
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• pp.251-263
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• 2023

In the setting of extended quasi b-metric spaces, we introduce a new concept called "extended A-contraction". We then use our concept to prove a common fixed point result for a pair of self mappings under a set of conditions. Also, we provide the concepts of extended B-contraction and extended R-contraction. We then establish a common fixed point under these new contractions. Our results generalize many existing result of fixed point in metric spaces. Furthermore, we give an example to illustrate and support our result.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권2호
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• pp.75-92
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• 2018

Based on Perceptions about Mathematics Teachers (PMT) perceived by high school students, measured by 2189 students from Seoul Educational Longitudinal Study 2014 (SELS 2014), latent profile analysis (LPA) identified five distinct types of student groups (positive, partial positive, middle, negative, extreme negative). These student of positive, middle, and negative groups are positive, moderate and negative perceptions about math teachers. Partial positive group generally had a positive perception about mathematics teachers, extremely negative group was very negative about mathematics teachers. Both of these groups had peculiarly inconsistent trends and several anomalies. The Multinomial logistic regression analyses also indicated that individual factors (gender, major, self-concept, resilience, self-assessment, career maturity), school factors (friendship, relationship with school teachers) and parental factors (academic-relationship, emotional-relationship) were significant predictors of PMT profile groups. The Analysis of variance also indicated that mathematics class (attitude, satisfaction and atmosphere), Mathematics achievement were significant predictors of PMT profile groups. The profiling of perceptions about mathematics teachers resulted in enhanced understanding of the complex range of processes students employed. During mathematics class, implementation of smooth interactions and communications between students and teachers added in the teaching and learning of mathematics.

• 대한수학회보
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• 제60권3호
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• pp.829-844
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• 2023

In this paper, we present a new construction for self-dual codes that uses the concept of double bordered construction, group rings, and reverse circulant matrices. Using groups of orders 2, 3, 4, and 5, and by applying the construction over the binary field and the ring F₂ + uF₂, we obtain extremal binary self-dual codes of various lengths: 12, 16, 20, 24, 32, 40, and 48. In particular, we show the significance of this new construction by constructing the unique Extended Binary Golay Code [24, 12, 8] and the unique Extended Quadratic Residue [48, 24, 12] Type II linear block code. Moreover, we strengthen the existing relationship between units and non-units with the self-dual codes presented in [10] by limiting the conditions given in the corollary. Additionally, we establish a relationship between idempotent and self-dual codes, which is done for the first time in the literature.

• 대한수학교육학회지:수학교육학연구
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• 제10권1호
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• pp.57-72
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• 2000

In this paper, in order to explicate how mathematics education can contribute to humanity education, I enquired in which position mathematics occupy in Froebel's For this, I examined Froebel's theory of humanity education, his theory of mathematics education, and the applicational problem of his thoughts to nowaday education. Froebel's educational theory is based on the concept of the Divine Unity which is relevant to the notion of 'The Absolute' of Fichte, Schelling, Hegel. He claims that from inanimate objects to human being, all is subject to the eternal law, which is presided by God. So the world itself is the representation of this law of the Divine Unity and education consists in leading man to conscious and free representation of it. The revealing process of the inner law of the Divine Unity can be attained through the awareness of the divinity which resides in the self. And this process of self-consciousness is dialectical movement of the two opposites, i.e. 'inner' and 'outer' Froebel suggests that mathematics is the mediator between the inner and outer world, i.e. he suggests that since both human being and nature are the representations of the Divine Unity, mathematics is both the pure human spirits and the law of nature. Having such a role, mathematics becomes the main discipline in education. Though there are some criticism on Froebel's educational thoughts on mathematics discussed in this paper, it can provide a typical answer to the question about how mathematics education contributes to humanity education.

• 대한수학회지
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• 제43권3호
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• pp.491-506
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• 2006

In this paper, we extend the concept of the group ${\varepsilon}(X)$ of self homotopy equivalences of a space X to that of an object in the category of pairs. Mainly, we study the group ${\varepsilon}(X,\;A)$ of pair homotopy equivalences from a CW-pair (X, A) to itself which is the special case of the extended concept. For a CW-pair (X, A), we find an exact sequence $1\;{\to}\;G\;{\to}\;{\varepsilon}(X,\;A)\;{to}\;{\varepsilon}(A)$ where G is a subgroup of ${\varepsilon}(X,\;A)$. Especially, for CW homotopy associative and inversive H-spaces X and Y, we obtain a split short exact sequence $1\;{\to}\;{\varepsilon}(X)\;{\to}\;{\varepsilon}(X{\times}Y,Y)\;{\to}\;{\varepsilon}(Y)\;{\to}\;1$ provided the two sets $[X{\wedge}Y,\;X{\times}Y]$ and [X, Y] are trivial.

• 충청수학회지
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• 제18권1호
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• pp.1-22
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• 2005

The object of this paper is to introduce the concept of a pair of semi-compatible self-maps in a fuzzy metric space to establish a fixed point theorem for four self-maps. It offers an extension of Vasuki [10] to four self-maps under the assumption of semi-compatibility and compatibility, repsectively. At the same time, these results give the alternate results of Grebiec [5] and Vasuki [9] as well.