• 대한수학회논문집
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• 제26권3호
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• pp.385-403
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• 2011

Generalizations of the notion of fuzzy hyper K-subalgebras are considered. The concept of fuzzy hyper K-subalgebras of type (${\alpha},{\beta}$) where ${\alpha}$, ${\beta}$ ${\in}$ {${\in}$, q, ${\in}{\vee}q$, ${\in}{\wedge}q$} and ${\alpha}{\neq}{\in}{\wedge}q$. Relations between each types are investigated, and many related properties are discussed. In particular, the notion of (${\in}$, ${\in}{\vee}q$)-fuzzy hyper K-subalgebras is dealt with, and characterizations of (${\in}$, ${\in}{\vee}q$)-fuzzy hyper K-subalgebras are established. Conditions for an (${\in}$, ${\in}{\vee}q$)-fuzzy hyper K-subalgebra to be an (${\in}$, ${\in}$)-fuzzy hyper K-subalgebra are provided. An (${\in}$, ${\in}{\vee}q$)-fuzzy hyper K-subalgebra by using a collection of hyper K-subalgebras is established. Finally the implication-based fuzzy hyper K-subalgebras are discussed.

• 대한수학회지
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• 제47권5호
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• pp.879-897
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• 2010

Y. Hirano introduced the concept of a quasi-Armendariz ring which extends both Armendariz rings and semiprime rings. A ring R is called quasi-Armendariz if $a_iRb_j$ = 0 for each i, j whenever polynomials $f(x)\;=\;\sum_{i=0}^ma_ix^i$, $g(x)\;=\;\sum_{j=0}^mb_jx^j\;{\in}\;R[x]$ satisfy f(x)R[x]g(x) = 0. In this paper, we first extend the quasi-Armendariz property of semiprime rings to the skew polynomial rings, that is, we show that if R is a semiprime ring with an epimorphism $\sigma$, then f(x)R[x; $\sigma$]g(x) = 0 implies $a_iR{\sigma}^{i+k}(b_j)=0$ for any integer k $\geq$ 0 and i, j, where $f(x)\;=\;\sum_{i=0}^ma_ix^i$, $g(x)\;=\;\sum_{j=0}^mb_jx^j\;{\in}\;R[x,\;{\sigma}]$. Moreover, we extend this property to the skew monoid rings, the Ore extensions of several types, and skew power series ring, etc. Next we define $\sigma$-skew quasi-Armendariz rings for an endomorphism $\sigma$ of a ring R. Then we study several extensions of $\sigma$-skew quasi-Armendariz rings which extend known results for quasi-Armendariz rings and $\sigma$-skew Armendariz rings.

• 대한수학회지
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• 제54권5호
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• pp.1505-1519
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• 2017

Assume that M is an R-module where R is a commutative ring. A proper submodule N of M is called a weakly 2-absorbing primary submodule of M if $0{\neq}abm{\in}N$ for any $a,b{\in}R$ and $m{\in}M$, then $ab{\in}(N:M)$ or $am{\in}M-rad(N)$ or $bm{\in}M-rad(N)$. In this paper, we extended the concept of weakly 2-absorbing primary ideals of commutative rings to weakly 2-absorbing primary submodules of modules. Among many results, we show that if N is a weakly 2-absorbing primary submodule of M and it satisfies certain condition $0{\neq}I_1I_2K{\subseteq}N$ for some ideals $I_1$, $I_2$ of R and submodule K of M, then $I_1I_2{\subseteq}(N:M)$ or $I_1K{\subseteq}M-rad(N)$ or $I_2K{\subseteq}M-rad(N)$.

• 한국정밀공학회지
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• 제19권9호
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• pp.157-165
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• 2002

The design of hydraulic & control system has been developed for the disc spinning machine. The hydraulic system has been designed in the overall system including the vertical & horizontal slide fur spinning works which are controlled by hydraulic servo valves in right & left side, and the clamping slide for holding & pressing blank material in center during spinning process. Based on the design concept of this hydraulic system, model test experiments for hydraulic servo control system is tested to conform confidence and applying possibility. The control system is introduced with the fuzzy-sliding mode controller for the hydraulic force control reacting force as a disturbance, because a fuzzy controller does not require an accurate mathematical model for the generation of nonlinear factors in the actual nonlinear plant with unknown disturbances and a sliding controller has the robustness & stability in mathematical control algorithm. We conform that the fuzzy-sliding mode controller has a good performance in force control for the plant with a strong disturbance. Also, we observe that a steady state error of the fuzzy-sliding mode controller can be reduced better than those of an another controllers.

• 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.

• 대한수학교육학회지:학교수학
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• 제4권2호
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• pp.297-316
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• 2002

In this paper, a teaching unit on series of number sentences with patterns is designed according to Wittmann's perspectives. In this paper, series of number sentences wish patterns means number sentences in which some patterns are contained. especially, seven kinds of number sentences wish patterns are offered as basic materials, and fifteen tasks based on these basic materials are offered. These tasks are for ninth grade students and higher grade students. These tasks heap students to recognize patterns, and to understand mechanism underlying in those patterns by looking for patterns and proving whether these patterns are generally hold. As working on these tasks, students can reinforce meaning of algebraic expression, its manipulation, and concept of number series. Students also can reinforce mathematical thinking such as analogical thinking, deductive thinking, etc. In this point, this teaching unit reveal important objectives, contents, and Principles of mathematics education. This teaching unit can also be rich sources for student's activities. Especially, for each task's level is different, each student's personal ability is considered fully. Since teachers can know mathematical facet, psychological facet, and didactical facet holistically, this teaching unit can offer broad possibilities for experimental studies. SD, this leaching unit can be said to be substantial. In this paper, this leaching unit is not applied in classroom directly. Actually such applying in classroom is suggested as follow-up studies. By appling this teaching unit in various classroom, some effective informations for teaching this teaching unit and some particular phenomenons in those teaching processes can be identified, and this teaching unit can be revised to be better one.

• 산업공학
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• 제12권1호
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• pp.10-18
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• 1999

Job shop manufacturing environments are using the concept of cellular manufacturing systems(CMS) which has several advantages in reducing production lead times, setup times, work-in-process, etc. Utilizing the similarities between cell-machine, part-machine, and the shape/size of parts, CMS can group machines and parts resulting in improved efficiency of this system. However, when grouping machines and parts in machine cells, there inevitably occurs exceptional elements(EEs), which can not operate in the same machine cell. Minimizing these EEs in CMS is a critical point that improving production efficiency. Constraints in machine duplication cost, machining process technology, machining capability, and factory space limitations are main problems that prevent achiving the goal of maintaining an ideal CMS environment. This paper presents an algorithm that minimizes EEs under the constraints of machine duplication cost and factory space limitation. Developing exceptional operation similarity(EOS) by cell-machine incidence matrix and part-machine incidence matrix, it brings the machine cells that operate the parts or not. A mathematical model to minimize machine duplication is developed by EOS, followed by a heuristic algorithm in order to reflect dynamic situation resulting from minimizing exceptional elements process and the mathematical model. A numerical example is provided to illustrate the algorithm.

• 한국학교수학회논문집
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• 제7권1호
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• pp.83-102
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• 2004

본 논문은 교육과정에서 초등학교 1학년 학생들에게 제시하고 있는 덧셈의 내용을 살펴보고 질문지와 인터뷰를 통해 덧셈의 학습 이전에 실제로 어린이들이 덧셈에서 사용하며 선호하는 전략을 알아보고 바람직한 수학 교수 학습의 방향에 시사점을 제공하고자 한다. 현행의 교육과정은 학습 초기부터 표준 알고리즘을 중심으로 지도 하도록 되어 있고, 교사들은 이러한 지식을 학생들의 수학적 성향과 무관하게 표준 알고리즘을 학생들에게 암암리에 강요하고 있는 실정이다. 교사는 학생들이 어떤 수 세기와 수 개념 단계에 이르렀는지 파악하고 그들의 수개념과 표준 알고리즘간의 효과적인 결합을 위해서 학생들의 풀이 전략을 좀 더 심층적으로 관찰할 필요가 있으며, 학생들의 비형식적인 지식을 형식적인 수학에 유연하게 접목하는 시도를 끊임없이 해야할 것이다.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제9권1호
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• pp.31-41
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• 2005

In modern theory, creativity is an aim of mathematics education not only for the gifted but also fur the general students. The assertion that we must cultivate the creativity for the gifted students and drill the mechanical activity for the general students are unreasonable. Freudenthal has advocated the reinvention method, a pedagogical principle in mathematics education, which would promote the creativity. In this method, the pupils start with a meaningful context, not ready-made concepts, and invent informative method through which he could arrive at the formative concepts progressively. In many face the reinvention method is contrary to the traditional method. In traditional method, which was named as 'concretization method' by Freudenthal, the pupils start with ready-made concepts, and applicate this concepts to various instances through which he could arrive at the understanding progressively. Freudenthal believed that the mathematical creativity could not be cultivated through the concretization method in which the teacher transmit a ready-made concept to the pupils. In the article, we close examined the reinvention method, and presented a context of delivery route which is a illustration of reinvention method. Through that context, the principle of pascal's triangle is reinvented progressively.

• 한국초등수학교육학회지
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• 제15권3호
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• pp.599-617
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• 2011

본 연구의 목적은 2009 개정 수학 교육과정에 따른 교과서 작업에 즈음하여 중국 교과서와 우리나라 교과서를 비교 분석함으로써 현재 교과서의 개선점을 지적하고 새 교과서 작업에 시사점을 주고자 한다. 분석 대상은 중국 인민교육출판사의 초등수학 교과서와 2007 개정 교육과정에 따른 우리나라 교과서이다. 분석 영역은 수와 덧셈, 뺄셈으로 제한했다. 본 연구의 결과는 한국 교과서가 상대적으로 많은 언어적 표현의 사용, 할 일이 정해진 활동, 수학적 개념의 확장에서 유사한 절차 사용, 수와 연산 영역에서 더 큰 수의 사용, 다양하지 못한 수 감각 활동으로 나타났다. 이에 우리나라 교과서가 수학적 흥미와 도전감, 기초기본 개념 형성에서 상대적으로 취약하다는 것을 말해준다.