• 충청수학회지
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• 제27권2호
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• pp.211-218
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• 2014

In 3-dimensional Euclidean space, the geometric figures of a regular curve are completely determined by the curvature function and the torsion function of the curve, and surfaces are the fundamental curved spaces for pioneering study in modern geometry as well as in classical differential geometry. In this paper, we define parametrizations for surface by using parametric functions whose images are in the normal plane of each point on a given curve, and then obtain some results relating the Gaussian curvature of the surface with curvature and torsion of the given curve. In particular, we find some conditions for the surface to have either nonpositive Gaussian curvature or nonnegative Gaussian curvature.

• East Asian mathematical journal
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• 제33권2호
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• pp.199-216
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• 2017

A rational number as operator is eventually that it is considered a mapping. Depending on how selecting domain (the target of operation by rational number) and codomain (including the results of operations by rational number), it is possible to see the rational in two aspects. First, rational numbers can be deal with functions if we choose the target of operation by rational number as a number field containing rationals. On the other hand, if we choose the target of operation by rational number as integral domain $\mathbb{Z}$, then rational numbers can be regarded as partial functions on $\mathbb{Z}$. In this paper, we regard the rational numbers with a view of partial functions, we investigate the theoretical background of the relationship between the multiplication of rational numbers and the composition of rational numbers as operators.

• 아동학회지
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• 제30권1호
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• pp.109-125
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• 2009

This study examined the effects of estimation activities on children's operation and measurement abilities. Subjects were 60 five-year-old children. This experiment used the untreated control group design with pretest and posttest. Instruments used to collect data were the Number and Operation and Measurement tests part of the Test of Mathematics Ability for Young Children (TMAYC) developed by Hong, Lee and Chung (2006). ANCOVA was employed for statistical analysis. Results of the posttest showed that children in the experimental group scored significantly higher on children's operation and measurement abilities than the control group. Results imply that an estimation program can be an effective teaching model for improving children's operation and measurement abilities.

• 대한수학회보
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• 제50권2호
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• pp.431-440
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• 2013

Let ($M^3$, $g$) be a 3-dimensional closed Sasakian spin manifold. Let $S_{min}$ denote the minimum of the scalar curvature of ($M^3$, $g$). Let ${\lambda}^+_1$ > 0 be the first positive eigenvalue of the Dirac operator of ($M^3$, $g$). We proved in [13] that if ${\lambda}^+_1$ belongs to the interval ${\lambda}^+_1{\in}({\frac{1}{2}},\;{\frac{5}{2}})$, then ${\lambda}^+_1$ satisfies ${\lambda}^+_1{\geq}{\frac{S_{min}+6}{8}}$. In this paper, we remove the restriction "if ${\lambda}^+_1$ belongs to the interval ${\lambda}^+_1{\in}({\frac{1}{2}},\;{\frac{5}{2}})$" and prove $${\lambda}^+_1{\geq}\;\{\frac{S_{min}+6}{8}\;for\;-\frac{3}{2}<S_{min}{\leq}30, \\{\frac{1+\sqrt{2S_{min}}+4}{2}}\;for\;S_{min}{\geq}30$$.

• 대한수학회보
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• 제36권1호
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• pp.25-31
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• 1999

Let $\nu$ be a positive Borel measure on a space of homogeneous type (X, d, $\mu$), satisfying the doubling property. A condition on a weight $\omega$ for whixh a maximal operator $M\nu f$(x) defined by M$mu$f(x)=supr>0{{{{ { 1} over {ν(B(x,r)) } INT _{ B(x,r)} │f(y)│d mu (y)}}}}, is of weak type (p,p) with respect to (ν, $omega$), is that there exists a constant C such that C $omega$(y) for a.e. y$\in$B(x, r) if p=1, and {{{{( { 1} over { upsilon (B(x,r) } INT _{ B(x,r)}omega(y) ^ (-1/p-1) d mu (y))^(p-1)}}}} C, if 1$infty$.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권2호
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• pp.125-128
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• 2004

Using the theory of Generalized Nets we have modelled the information exchange within the electronic archives of an idealized univerity Intranet.

• 응용통계연구
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• 제7권2호
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• pp.239-248
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• 1994

지수혼합 시계열 모형인 EARMA(1,1) 모형이 율-워커 추정법과 조건최소제곱 추정법으로 추정되었다. 율-워커 추정량은 이동평균모수가 포함된 ERAMA(1,1) 모형인 경우 유일하지 못하므로 가역 조건을 만족하는 추정량이 유일한 추정량으로 얻어졌고, 조건최소제곱 추정량은 근사추정량이 얻어졌다. 모의 실험을 통하여 근사조건제곱 추정량은 율-워커 추정량보다 평균제곱오차면에서 훨씬 좋은 추정량으로 나타났다.

• 대한수학회논문집
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• 제37권2호
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• pp.347-358
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• 2022

In this paper, we first introduce the notions of superfluous and coessential subacts. Then hollow and co-uniform S-acts are defined as the acts that all proper subacts are superfluous and coessential, respectively. Also it is indicated that the class of hollow S-acts is properly between two classes of indecomposable and locally cyclic S-acts. Moreover, using the notion of radical of an S-act as the intersection of all maximal subacts, the relations between hollow and local S-acts are investigated. Ultimately, the notion of a supplement of a subact is defined to characterize the union of hollow S-acts.

• East Asian mathematical journal
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• 제25권4호
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• pp.441-447
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• 2009

Jat and Choudhari defined a near-ring R with left bipotent or right bipotent condition in 1979. Also, we can dene a near-ring R as subcommutative if aR = Ra for all a in R. From these above two concepts it is natural to investigate the near-ring R with the properties aR = $Ra^2$ (resp. $a^2R$ = Ra) for each a in R. We will say that such is a near-ring with (1,2)-potent condition (resp. a near-ring with (2,1)-potent condition). Thus, we can extend a general concept of a near-ring R with (m,n)-potent condition, that is, $a^mR\;=\;Ra^n$ for each a in R, where m, n are positive integers. We will derive properties of near-ring with (1,n) and (n,1)-potent conditions where n is a positive integer, any homomorphic image of (m,n)-potent near-ring is also (m,n)-potent, and we will obtain some characterization of regular near-rings with (m,n)-potent conditions.

• 한국산학기술학회논문지
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• 제21권9호
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• pp.387-396
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• 2020

본 연구의 목적은 단위학교 학업성취도에 영향을 주는 시·도교육청의 변인을 확인하고, 시·도교육청 지원에 따라 학업성취도가 동태적으로 어떻게 변화하는지 예측하는 것이다. 이를 위해 16개 시·도교육청 총 606개 일반계고의 국가 수준학업성취도(국어·영어·수학 교과의 보통학력 이상 도달 비율) 결과를 다층모형과 시스템 다이내믹스를 활용하여 분석하였다. 분석 결과, 시·도교육청 수준의 지방교육재정 효율화 노력과 교원행정업무 경감 노력, 교원연수 활성화 노력이 단위학교 학업성취도에 영향을 미치는 시·도교육청 변인으로 확인되었다. 또한 정책 실험을 통해 단위학교 학업성취도의 동태적 변화를 예측한 결과, 교원연수 활성화 노력이 단위학교 학업성취도의 가장 큰 영향 요인으로 확인되었고, 지방교육재정 효율화 노력, 교원 행정업무 경감 노력 순이었다. 단위학교 학업성취도의 향상을 위해 시·도교육청의 기능은 교육 책무성에 기반을 두어야 하며 중장기적인 관점에서 보다 강화된 정책을 수립·운영할 필요가 있다.