• 대한수학교육학회지:학교수학
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• 제4권3호
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• pp.415-433
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• 2002

The mathematics education community is seeking to change a teacher-centered class-room culture to a student-centered culture. However, the real transition is not easy, even for teachers who are eager and willing to teach differently. The challenge for teachers is to use the social structure of the classrooms to nurture students' development toward mathematical ways of thinking and communicating as well as their under-standing of mathematical concepts and processes. By introducing an elementary teacher's teaching practice and professional develop-ment along with her classroom episodes, this paper is to make strides toward an enriched understanding of the culture of the elementary mathematics classrooms in which students may have a lot of opportunities to develop conceptual under standing and math-ematical disposition. This paper first provides a detailed description of the classroom flow in terms of general social norms and sociomathematical norms in order to explore how the teacher and the students have established such a student-centered math-ematics microculture. This paper then analyzes the teacher's teaching approach and professional development.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제7권2호
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• pp.73-90
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• 2003

In the Republic of Korea, mathematics has always been a major blame for huge private expenditures on so-called "private education," which consists of private tutoring and lessons at "private academies of extra curricula." The private spending on out-of-school education often exceeded public expenditures on schools. In 1997, South Korean Ministry of Education reformed curriculum of mathematics along with other subjects to ease the burden of private education. The aim of this curriculum change was to put a boost on individual students' interests, affections and other attributes toward school mathematics. The essential distinctiveness of the new curriculum of mathematics compared with the previous one is as follows: 1. The implementation of so-called "differentiated curriculum" for grades 1-10. 2. 30% reduction of contents in mathematics and the reconciliation of contents. 3. Elective subjects for mathematics for grades 11 and 12. 4. More uses of technology in mathematics teaching. Firstly, we examine the background of the curriculum reform and analyze the new curriculum according to awareness of educational administrators, teaching environments of schools and readiness of mathematics teachers. Then we find out what kinds of problems it has and look for some suggestions for remedies.

• 인터넷정보학회논문지
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• 제9권5호
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• pp.109-116
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• 2008

컴퓨터와 인터넷 환경의 급속한 변화는 방대한 데이터와 다양한 품질의 데이터를 생산해내고 있다. 이러한 환경의 변화는 데이터의 품질에 따른 수준 평가를 요구한다. 이는 데이터 품질이 기업과 조직에 미치는 영향이 크기 때문이다. 따라서 본 연구는 데이터 품질 기준에 따른 품질 평가 모델을 수학적 모델로 제시하고, 이를 기반으로 데이터의 품질을 분석하고 데이터의 품질을 유지 보완하기 위한 분석 모형을 제안하고자한다.

• 전기학회논문지
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• 제56권3호
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• pp.481-490
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• 2007

WASP which is used to plan generation expansion has disadvantages that can't manage environmental factors and regional supply-demand planning. But with the effectuation of the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol, it is expected that reducing greenhouse gases affects power system in its long-term generation expansion planning. Therefore national countermeasures is needed. This paper formulates a mathematical model considering CO2 emission constraints and Emission Trading that will be enforced. This model is based on the MEFISET (Model for Economic Feasibility of Interstate Electrical Ties) which was made by Korea Energy Economics Institute and Hong-ik university and manages generation expansion planning. And this mathematical model is verified by studying a case system.

• 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.

• Steel and Composite Structures
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• 제24권1호
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• pp.53-63
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• 2017

The paper presents the simplified matrix stiffness method for analysis of composite and prestressed beams. The method is based on the previously developed "exact" analysis method that uses the mathematical theory of linear integral operators to derive all relations without any mathematical simplifications besides inevitable idealizations related to the material rheological properties. However, the method is limited since the closed-form solution can be found only for specific forms of the concrete creep function. In this paper, the authors proposed the simplified analysis method by introducing the assumption that the unknown deformations change linearly with the concrete creep function. Adopting this assumption, the nonhomogeneous integral system of equations of the "exact" method simplifies to the system of algebraic equations that can be easily solved. Therefore, the proposed method is more suitable for practical applications. Its high level of accuracy in comparison to the "exact" method is preserved, which is illustrated on the numerical example. Also, it is more accurate than the well-known EM method.

• 대한수학회논문집
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• 제21권1호
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• pp.177-183
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• 2006

The purpose of this paper is to introduce an L-metrical non-linear connection $N_j^{*i}$ and investigate a conformal change in the Finsler space with $({\alpha},\;{\beta})-metric$. The (v)h-torsion and (v)hvtorsion in the Finsler space with L-metrical connection $F{\Gamma}^*$ are obtained. The conformal invariant connection and conformal invariant curvature are found in the above Finsler space.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.46-48
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• 2006

WASP which is used to plan generation expansion has disadvantages that can't manage environmental factors and regional supply-demand planning. But with the effectuation of the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol, it is expected that reducing greenhouse gases affects power system in its long-term generation expansion planning. Therefore national countermeasures is needed. This paper formulates a mathematical model considering CO2 emission constraints and Emission Trading that will be enforced. This model is based on the ORIRES which was made by ESI, Russia and manages generation expansion planning. And this mathematical model is verified by studying a case system.

• East Asian mathematical journal
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• 제24권1호
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• pp.45-55
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• 2008

We consider an M/G/1 queue with $P^M_{\lambda}$-service policy, which is a two-stage service policy. The server starts to serve with rate 1 if a job arrives to the sever in idle state. If the workload of the system upcrosses $\lambda$, then the service rate is changed to M and this rate continues until the system is empty. It costs to change the service rate to M and maintaining the rate. When the expectation of the stationary workload is supposed to be less than a given value, we derive the optimal value of M.

• 유공압시스템학회논문집
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• 제8권2호
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• pp.17-22
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• 2011

The analysis of an air spring characteristics is necessary to design and control automotive air suspension system properly. A mathematical model of an air spring was derived in light of energy conservation first. Then static and dynamic experiments of the air spring have been fulfilled. The static stiffness with various initial pressures and effective areas were obtained from the static experimental results. Theoretical static stiffness obtained by using the mathematical model and effective area data is in close accordance with the experimental estimation. The dynamic experimental results show that the hysteresis in displacement-force cycle decreases when the frequency of the harmonic displacement excitation signal increases, but it does not change too much as the frequency is higher than 1Hz. And the dynamic stiffness goes up with increasing of the initial pressure and the excitation frequency.