• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.323-328
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• 1992

The vibrations of the main spindles of the M/C tools is the most important in the con- sideration of the dynamic performance of the M/C tools. In order to analyze and predict the dynamic behaviour of the machine tool structure it is necessary to have the mathematical model of the system. The system identification is the procedure to provide us with the mathematical model of the system of which we want to know the dynamic characteristics. This study illustrates a procedure of the system identification of the structure of the M/C tools to predict the dynamic behaviour of the machine and further to have the basis for the design of M/C tools.

• 한국정밀공학회지
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• 제10권1호
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• pp.142-146
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• 1993

The vibrations of the main spindle of the M/C tools are most important in the consideration of the dymamic performance of the M/C tools. In order to resolve and predict the dynamic behaviour of the main syindle it is necessary to have the mathematical model of the system. The system identification is the procedure to provide us with the mathematical model of the procedure of the system identification of the main spindle of the M/C tools to predict the dynamic behaviour of the machine and further to have the basis for the design of M/C tools.

• Structural Engineering and Mechanics
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• 제14권2호
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• pp.223-236
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• 2002

The main objective of the present paper is to address a formal procedure for orthotropic steel plates design. The theme of the proposed approach is to recast the design procedure into a mathematical programming model. The objective function to be optimized is the total weight of the structure. The total weight is function of its layout parameters and structural element design variables. Mean while the proposed approach takes into consideration the strength and rigidity criteria in addition to other dimensional constraints. A nonlinear programming model is developed which consists of a nonlinear objective function and a set of implicit/explicit nonlinear constraints. A transformation method is adopted for minimization strategy, where the primal model constrained problem is transformed into a sequence of unconstrained minimization models. The search strategy is based on the well-known Fletcher/Powell algorithm. The finite element technique is adopted for discretization and analysis strategies. Mindlin theory is selected to simulate the finite element model and a selective reduced integration scheme is exploited to avoid a shear lock problem.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제17권1호
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• pp.15-27
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• 2013

Division of fractions is always a difficult topic for primary school students. Most of the presentations in teaching the topic in textbooks are procedural, asking students to invert the second fraction and multiply it with the first one, that is, $$\frac{a}{b}{\div}\frac{c}{d}=\frac{a}{b}{\times}\frac{d}{c}$$. Such procedural approach in teaching diminishes both the understanding of structure in mathematics and the interest in learning the subject. This paper discussed the formulation of teaching the division of fractions, which based on research lessons in some primary five classrooms. The formulated lessons started with an analogy to division of integers and working with division of fractions with equal denominators and then extended to division of fractions in general. It is found that the using of analogy helps students to invent their procedure in working the division problem. Some procedures found by students are discussed, with the focus on the development of their invention and mathematical thinking.

• 한국수학교육학회지시리즈A:수학교육
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• 제41권3호
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• pp.329-339
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• 2002

This study analyzes the epistemological meaning of‘social construction’in mathematical instruction. The perspective that consider the cognition of mathematical concept as a social construction is explained by a cyclic scheme of an academic context and a school context. Both of the contexts require a public procedure, social conversation. However, there is a considerable difference that in the academic context it is Lakatos' ‘logic of mathematical discovery’In the school context, it is Vygotsky's‘instructional and learning interaction’. In the situation of mathematics education, the‘society’which has an influence on learner's cognition does not only mean‘collective members’, but‘form of life’which is constituted by the activity with purposes, language, discourse, etc. Teachers have to play a central role that guide and coordinate the educational process involving interactions with learners in this context. We can get useful suggestions to mathematics education through this consideration of the social contexts and levels to form didactical situations of mathematics.

• 한국해양공학회지
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• 제37권3호
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• pp.81-88
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• 2023

Maneuverability is a crucial factor for the safety and success of submarine missions. This paper introduces a mathematical model that considers the large drift and angle of attack motions of submarines. Various computational fluid dynamics (CFD) simulations were performed to adapt Karasuno's fishery vessel maneuvering mathematical model to submarines. The study also presents the procedure for obtaining the physics-based hydrodynamic coefficients proposed by Karasuno through CFD calculations. Based on these coefficients, the reconstructed forces and moments were compared with those obtained from CFD and to the hydrodynamic derivatives expressed by a Taylor expansion. The study also discusses the mathematical maneuvering model that accounts for the large drift angles and angles of attack of submarines. The comparison results showed that the proposed maneuvering mathematical model based on modified Karasno's model could cover a large range of motions, including horizontal motion and vertical motions. In particular, the results show that the physics-based mathematical maneuvering model can represent the forces and moments acting on the submarine hull during large drift and angle of attack motions. The proposed mathematical model based on the Karasuno model could obtain more accurate results than the Taylor third-order approximation-based mathematical model in estimating the hydrodynamic forces acting on submarines during large drift and angle of attack motions.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제20권1호
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• pp.85-99
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• 2017

수학 문제해결 능력의 향상을 위한 연구의 일환으로 문제해결 활동 과정에 중요한 역할을 담당하는 것으로 최근에 파악된 메타정의를 수학 학습 지도에 적용하는 연구의 필요성이 제기되어왔다. 이에 본 연구에서는 긍정적인 메타정의의 기능을 활성화시키며 실제 문제해결 활동에 효과적으로 작용하는 것은 물론, 정의적 측면에 대한 연구방법론이 갖는 일반적인 난점의 극복을 위하여 협업의 상황을 설정하였다. 즉, 2인 1조의 소집단 구성원이 협업을 통하여 성공적인 문제해결 과정에 보여주는 메타정의적 요소에 대한 사회역학적 작용 과정의 특성을 분석하였다. 이를 위해 선행연구에서 파악된 메타정의의 메타적 기능 유형과 협업의 교류적 요소를 초등학생의 협업적 문제해결 활동 분석을 위한 준거로 삼았다. 소집단의 협업적 수학 문제해결 활동의 에피소드 단위별로 보여주는 메타정의의 메타적 기능 유형과 이와 결부된 교류적 요소의 구조 사례를 관찰, 분석하여 성공적인 문제해결로 유도하는 메타정의의 사회역학적 기능이 보여주는 특성을 추출하였다. 본 연구의 결과로부터 도출되는 메타정의의 사회역학적 작용 원리는 성공적인 수학 문제해결의 교수 학습 방법 구현을 위한 연구에 정의적, 사회역학적 측면에서 실제적인 시사점을 제공한다.

• Structural Engineering and Mechanics
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• 제24권2호
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• pp.155-180
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• 2006

Many applications in mechanical design involve elastic bodies coming into contact under the action of the applied load. The distribution of the contact pressure throughout the contact interface plays an important role in the performance of the contact system. In many applications, it is desirable to minimize the maximum contact pressure or to have an approximately uniform contact pressure distribution. Such requirements can be attained through a proper design of the initial surfaces of the contacting bodies. This problem involves a combination of two disciplines, contact mechanics and shape optimization. Therefore, the objective of the present paper is to develop an integrated procedure capable of evaluating the optimal shape of contacting bodies. The adaptive incremental convex programming method is adopted to solve the contact problem, while the augmented Lagrange multiplier method is used to control the shape optimization procedure. Further, to accommodate the manufacturing requirements, surface parameterization is considered. The proposed procedure is applied to a couple of problems, with different geometry and boundary conditions, to demonstrate the efficiency and versatility of the proposed procedure.

• 한국경영과학회지
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• 제20권2호
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• pp.77-93
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• 1995

A mathematical model for long-rage water supply planning was formulated as a dynamic plant location problem with network arc capacity expansion, and illustative example was presented. The proposed solution procedure identifies economical construction timings of surface water supply facilities and water conveyence systems and the best water supply operating patterns as well. In this study, we present a heuristic solution procedure using Simulated annealing Method in conjunction with Bertsekas & Tseng's RELAXT-II for the 0-1 integer network problem.

• 호남수학학술지
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• 제23권1호
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• pp.145-158
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• 2001

In this paper we investigated a replacement model with two types of repairs. Repairs are classified into minimal and perfect repair. An operating unit is completely replaced whenever it reaches age ${\tau}({\tau}>0)$(planned replacement). If it fails at age $t<{\tau}$, it is either restored by a entire unit with probability p(t)(perfect repair), or it undergoes minimal repair with probability $\bar{p}(t)=1-p(t)$. After a planned replacement, the procedure is repeated.