• 대한수학교육학회지:수학교육학연구
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• 제24권3호
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• pp.467-480
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• 2014

초등 수학에서 지도하는 수학적 개념 중에는 구체적 조작 활동에만 의존할 것이 아니라 형식화된 사고 활동을 함께 요구할 필요가 있는 경우도 있는데 그 대표적인 것이 분수 개념이다. 가분수 개념을 도입하기 위해서는 그 이전에 두 자연수 관계로서의 분수 개념을 지도하여야 한다. 이 활동은 자연수를 몇씩 묶어 나눈 양으로서의 분수의 지도와 관련해서도 생략해서는 안 되는 중요한 활동이다. 대분수는 간단한 분수의 합과 차를 구하는 활동이 이루어진 후, 자연수와 분수의 합이라는 형식화된 추상적 개념으로 지도하여야 한다. 몫으로서의 분수 개념은 구체적 조작 활동에서 직접 도출될 수 없는 이차적 사고 또는 형식적 사고를 요구한다. 초등학생들의 논리적 사고 수준을 고려한다면 자연수 나눗셈의 곱셈 변환을 지도한 뒤에 곱셈의 결과로서 몫 분수를 표현하는 방법을 지도하는 것이 바람직하다.

• 한국수학교육학회지시리즈A:수학교육
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• 제4권1호
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• pp.16-28
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• 1966

According to the modernization of mathematics education, new abstract concepts such as the concept of sets are introduced in many fields of it. The purpose of this thesis is to adopt the concept of sets to 'probability' which is included in the curriculum of high school matematics education. The considerations of the preceding chapter III, and their obvious generalizations to more complicated experiments, justify the conclusion that probability theory consists of the study of sets. An event is a set, its opposite event is the complementary set; mutually exclusive events are disjoint sets, and an event consisting of the simultaneous occurrence of two other events is a sets obtained by intersecting two other sets it is clear how this glossary, translating physical terminology into set theoretic terminology, may be continued. Furthermore, the important theorems of probability; Additional theorem, multiplication theorem, their applications and so on, are proved by the technical operations of sets. Thinking of the mathematics education introduced by the concept of sets is very important in future.

• 대한수학교육학회지:수학교육학연구
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• 제12권1호
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• pp.1-16
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• 2002

The 7th Curriculum emphasizes that in mathematics classes, mathematical concepts be understood and mathematical problems be solved through student's own exploratory activities including the use of data, manipulatives, andtechnological devices. Following the main idea of the Seventh Mathematics Curriculum, this paper dealt with instructional methods applied suitably and effectively in mathematics classes, and focused on the 'exploratory learning in groups' method in mathematics education. For this purpose, this paper reviewed and summarized theories related to general pedagogy and of mathematics education. Based on the results, it investigated appropriate instructional methods in mathematics education. In particular, this paper focused on studying the exploratory learning method while investigating its properties and understand- ing the relationship between the 'exploratory learning in groups' method and the discussion-centered method. Finally, in order to show the usefulness of the exploratory learning method, this paper developed an example of a teaching module using the exploratory learning method in addition to discussion and lecture-centered methods by the use of manipulatives. The main goal of the module was to make students understand the principle of multiplication of integers.

• 한국정밀공학회지
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• 제28권5호
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• pp.632-637
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• 2011

A new tooth profile which is adjusted on the amount of addendum modification factor is proposed for reducing vibration and noise of gears. The transmission error of the new profile can be designed more uniformly than that of the standard involute profile. The basic concepts of tooth profile modification are to reduce the load in contact area and to find the appropriate profile modification factor for operation condition. In this study, gears were estimated to constructive safety of bending strength and contact strength durability by using ROMAX program, and were compared with results by design formula of AGMA standard.

• 대한수학회보
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• 제32권2호
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• pp.337-342
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• 1995

A semiring is a binary system $(S, +, \times)$ such that (S, +) is an Abelian monoid (identity 0), (S,x) is a monoid (identity 1), $\times$ distributes over +, 0 $\times s s \times 0 = 0$ for all s in S, and $1 \neq 0$. Usually S denotes the system and $\times$ is denoted by juxtaposition. If $(S,\times)$ is Abelian, then S is commutative. Thus all rings are semirings. Some examples of semirings which occur in combinatorics are Boolean algebra of subsets of a finite set (with addition being union and multiplication being intersection) and the nonnegative integers (with usual arithmetic). The concepts of matrix theory are defined over a semiring as over a field. Recently a number of authors have studied various problems of semiring matrix theory. In particular, Minc [4] has written an encyclopedic work on nonnegative matrices.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.23-25
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• 2007

The partial distortion elimination (PDE) scheme is used to decrease the sum of absolute difference (SAD) computational complexity, since the SAD calculation has been taken much potion of the video compression. In motion estimation (ME) based on PDE, it is ideal that the initial value of SAD in summing performance has large value. The traditional scan order methods have many operation time and high operational complexity because these adopted the division or multiplication. In this paper, we introduce the new scan order and search order by using only adder. We define the average value which is called to rough average value (RAVR). Which is to reduce the computational complexity and increase the operational speed and then we can obtain the improvement of SAD performance. And also this RAVR is used to decide the search order sequence, since the difference RAVR between the current block and candidate block is small then this candidate block has high probability to suitable candidate. Thus, our proposed algorithm combines above two main concepts and suffers the improving SAD performance and the easy hardware implementation methods.

• 대한수학회지
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• 제51권3호
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• pp.509-525
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• 2014

Let R be a commutative ring with identity. An R-module M is said to be w-projective if $Ext\frac{1}{R}$(M,N) is GV-torsion for any torsion-free w-module N. In this paper, we define a ring R to be w-semi-hereditary if every finite type ideal of R is w-projective. To characterize w-semi-hereditary rings, we introduce the concept of w-injective modules and study some basic properties of w-injective modules. Using these concepts, we show that R is w-semi-hereditary if and only if the total quotient ring T(R) of R is a von Neumann regular ring and $R_m$ is a valuation domain for any maximal w-ideal m of R. It is also shown that a connected ring R is w-semi-hereditary if and only if R is a Pr$\ddot{u}$fer v-multiplication domain.

• 한국학교수학회논문집
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• 제16권1호
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• pp.31-61
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• 2013

본 연구의 목적은 학습능력이 다소 처지는 학생들도 구성주의를 바탕으로 한 학습자 중심 수업을 받았을 때 이들도 또한 스스로 지식을 구성할 수 있을 것이라는 구성주의자들의 가정을 확인을 하는데 있다. 이런 목적을 달성하기 위해서, 연구자들은 구성주의를 바탕으로 한 학습자 중심 수업과 객관적 인식론을 바탕으로 한 교사 중심 수업이 학생들의 추론 능력과 학업성취도에 미치는 효과를 비교하였다. 이를 알아보기 각 집단은 각 실험처치를 통해 곱셈을 학습하였다. 본 연구에서 얻은 결과로부터 다음과 같은 몇가지 결론을 얻을 수 있었다. 첫 번째, 구성주의를 바탕으로 한 학습자 중심 수업은 학습자들의 추론 능력에 통계적으로 유의미한 영향을 미쳤다. 두 번째, 학습자 중심 수업은 학습자들의 연역적 추론 능력에 다소 긍정적인 영향을 미쳤다. 세 번째, 다소 학습능력이 처지는 학생들을 대상으로 실시한 학습자 중심 수업은 교사중심 수업보다 실험처치 중 학습하지 않은 수학적 지식의 개념 및 원리 이해에 긍정적인 영향을 미쳤다.

• 한국수학교육학회지시리즈A:수학교육
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• 제57권4호
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• pp.453-475
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• 2018

This study examines how elementary students understand fractions with operations conceptually and how they perform procedures in the division of fractions. We attempted to look into students' understanding about fractions with divisions in regard to mathematical proficiency suggested by National Research Council (2001). Mathematical proficiency is identified as an intertwined and interconnected composition of 5 strands- conceptual understanding, procedural fluency, strategic competence, adaptive reasoning, and productive disposition. We developed an instrument to identify students' understanding of fractions with multiplication and division and conducted the survey in which 149 6th-graders participated. The findings from the data analysis suggested that overall, the 6th-graders seemed not to understand fractions conceptually; in particular, their understanding is limited to a particular model of part-whole fraction. The students showed a tendency to use memorized procedure-invert and multiply in a given problem without connecting the procedure to the concept of the division of fractions. The findings also proposed that on a given problem-solving task that suggested a pathway in order for the students to apply or follow the procedures in a new situation, they performed the computation very fluently when dividing two fractions by multiplying by a reciprocal. In doing so, however, they appeared to unable to connect the procedures with the concepts of fractions with division.

• Kyungpook Mathematical Journal
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• 제51권1호
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• pp.93-108
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• 2011

A ring R is called left weakly np- injective if for each non-nilpotent element a of R, there exists a positive integer n such that any left R- homomorphism from $Ra^n$ to R is right multiplication by an element of R. In this paper various properties of these rings are first developed, many extending known results such as every left or right module over a left weakly np- injective ring is divisible; R is left seft-injective if and only if R is left weakly np-injective and $_RR$ is weakly injective; R is strongly regular if and only if R is abelian left pp and left weakly np- injective. We next introduce the concepts of left weakly pp rings and left weakly C2 rings. In terms of these rings, we give some characterizations of (von Neumann) regular rings such as R is regular if and only if R is n- regular, left weakly pp and left weakly C2. Finally, the relations among left C2 rings, left weakly C2 rings and left GC2 rings are given.