• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
• /
• pp.998-999
• /
• 2006

A new mathematical simulation technique for physico-mechanical properties of multi-component powder materials is proposed in this paper. The main advantage of the technique is that finite elements representing different components are placed into a common mesh and may exchange their properties. The output data are properties of material after sintering. The technique allows us to investigate the influence of each component of a material on the properties and distribution of properties inside the sample. The comparative analysis of materials with different compositions is based on simulation results that are well concordant with the results of the laboratory experiments.

• 대한기계학회논문집A
• /
• 제24권12호
• /
• pp.3080-3087
• /
• 2000

We obtain the mathematical model of the hard disk drive actuator system the system response data of the finite element analysis or experimental results. The model is base on the Rayleigh-Ritz method to approximate the dynamic response of the actuator system. The basic idea is to use the curve-fit technique to obtain the approximation coefficients. It allows the dynamic analysis of the actuator system without resort to the repetitive finite element modeling work. Even though the dynamic characteristics of the system of the system are affected somewhat by the structural modification and the change of the material properties, we can use the modified size and dynamic properties of the actuator system in the mathematical model to some extent. In this study, we express the mathematical model of the simplified rectangular plate first and then proceed to the actual hard disk drive actuator system.

• 대한수학교육학회지:학교수학
• /
• 제12권3호
• /
• pp.337-351
• /
• 2010

게임은 일정한 크기의 체스판 모양의 사각판 위에서 일정한 규칙으로 칸의 색깔을 바꾸어 가면서 모든 칸의 색을 통일하는 것을 목표로 하는 게임이다. 이 게임의 규칙은 단순하지만 그 안에는 다양한 수학적 모델링이 포함되어 있다. 본 연구는 흑백게임을 소재로 S대학부설 과학영재교육원의 R&E 프로그램을 진행하면서 중학교 수학영재학생들이 수학적 모델링을 만들어보고 탐구해가는 소재를 개발하였다. 그 결과 이 게임을 수학영재교육용 수업이나 수학영재들의 연구 소재로 활용할 수 있는 4가지 수학적 모델링(패턴 분석, 대응 관계, 동치류 분석, 선형대수학적 분석)이 가능함을 확인하고 더불어 교사들이 유용하게 활용할 수 있도록 각각의 모델링 유형별로 몇 가지 발문도 제안한다.

• 대한수학교육학회지:수학교육학연구
• /
• 제8권2호
• /
• pp.405-423
• /
• 1998

This study aims to reflect the origin and the meaning of open education and to derive pedagogical principles for open mathematics education. Open education originates from Socrates who was the founder of discovery learning and has been developed by Locke, Rousseau, Froebel, Montessori, Dewey, Piaget, and so on. Thus open education is based on Humanism and Piaget's psychology. The aim of open education consists in developing potentials of children. The characteristics of open education can be summarized as follows: open curriculum, individualized instruction, diverse group organization and various instruction models, rich educational environment, and cooperative interaction based on open human relations. After considering the aims and the characteristics of open education, this study tries to suggest the aims and the directions for open mathematics education according to the philosophy of open education. The aim of open mathematics education is to develop mathematical potentials of children and to foster their mathematical appreciative view. In order to realize the aim, this study suggests five pedagogical principles. Firstly, the mathematical knowledge of children should be integrated by structurizing. Secondly, exploration activities for all kinds of real and concrete situations should be starting points of mathematics learning for the children. Thirdly, open-ended problem approach can facilitate children's diverse ways of thinking. Fourthly, the mathematics educators should emphasize the social interaction through small-group cooperation. Finally, rich educational environment should be provided by offering concrete and diverse material. In order to make open mathematics education effective, some considerations are required in terms of open mathematics curriculum, integrated construction of textbooks, autonomy of teachers and inquiry into children's mathematical capability.

• Structural Engineering and Mechanics
• /
• 제84권2호
• /
• pp.285-293
• /
• 2022

Lumped damage mechanics (LDM) is a recent nonlinear theory with several applications to civil engineering structures, such as reinforced concrete and steel buildings. LDM apply key concepts of classic fracture and damage mechanics on plastic hinges. Therefore, the lumped damage models are quite successful in reproduce actual structural behaviour using concepts well-known by engineers in practice, such as ultimate moment and first cracking moment of reinforced concrete elements. So far, lumped damage models are based in the strain energy equivalence hypothesis, which is one of the fictitious states where the intact material behaviour depends on a damage variable. However, there are other possibilities, such as the energy equivalence hypothesis. Such possibilities should be explored, in order to pursue unique advantages as well as extend the LDM framework. Therewith, a lumped damage model based on the energy equivalence hypothesis is proposed in this paper. The proposed model was idealised for reinforced concrete structures, where a damage variable accounts for concrete cracking and the plastic rotation represents reinforcement yielding. The obtained results show that the proposed model is quite accurate compared to experimental responses.

• 한국산학기술학회논문지
• /
• 제19권8호
• /
• pp.146-159
• /
• 2018

본 연구는 4D프레임 교구를 활용한 유아수학활동이 만 5세 유아의 수학적 능력과 태도에 미치는 영향을 알아보기 위해 수행되었다. 이를 위해 S시에 위치한 E, K, Y유치원의 만 5세 유아 56명을 실험집단(I: n=14, II: n=14)과 비교집단(III, n=14, IV, n=14)으로 나눈 후 8주 동안 실험집단에서 4D프레임 교구를 활용한 유아수학활동을 실시하였고 비교집단은 각각 누리과정에서 제시하는 수학활동과 수 과학 통합프로그램을 실시하였다. 실험집단(I, II)과 비교집단(III, IV)의 사전검사 점수를 공변인으로 하여 공변량분석(ANCOVA)을 실시한 결과, 4D프레임 교구를 활용한 유아수학활동이 실험집단과 비교집단 간 통계적으로 유의미한 차이가 있는 것으로 나타났고 이는 4D프레임 교구를 활용한 유아수학활동이 유아의 수학적 능력과 수학적 태도의 향상에 긍정적인 영향을 준 것으로 해석할 수 있다. 본 연구를 통해 유아교육 현장에서 4D프레임 교구를 활용한 유아수학활동의 효율성을 이해함으로써 유아들의 수학적 능력 및 태도의 향상을 위한 현장 적용 가능한 교육적 방안을 위한 기초자료를 제공하고자 한다.

• 한국수학교육학회지시리즈C:초등수학교육
• /
• 제10권1호
• /
• pp.57-70
• /
• 2007

수학사 관련 교수 학습 자료 개발에만 치중하였고 개발한 교수 학습 자료는 학습내용에 알맞은 수학사나 수학자의 일화로 실제 수업시간 중 흥미유발 자료로 사용하는데 그쳤다. 본 연구에서는 수학사를 보다 적극적으로 활용하기 위해서 문제 파악, 문제추구 및 해결, 적용 발전, 과제 파악 등의 각 학습 단계에서 활용할 수 있는 수학사 자료를 개발하여 실제 수업에 적용해 봄으로써 수학 사업을 개선하는데 도움을 주고자 하였다.

• 한국정밀공학회지
• /
• 제28권9호
• /
• pp.1054-1061
• /
• 2011

GMA welding process is a production process to improve productivity for the provision of higher quality of material, These includs numerous process variables that could affect welding quality, productivity and cost savings. Recently, the welding part of construction equipment had frequent failure of major components in the welding part of each subsidiary material due to shock which is very poor according to the welding part. Therefore, the implementation of sound welding procedure is the most decisive factor for the reliability of construction machinery. The data generated through experimens conducted in this study has validated its effectiveness for the optimization of bead geometry and process variables is presented. The criteria to control the process parameters, to achieve a healthy bead geometry. This study has developed mathematical models and algorithms to predict or control the bead geometry in GMA fillet welding process.

• 한국학교수학회논문집
• /
• 제15권1호
• /
• pp.183-197
• /
• 2012

평면기하는 가장 오래 된 학교수학 학습내용 중 하나이며, 중등학교에서 학생들의 사고력 및 창의력 신장에 중요한 역할을 한다. 평면기하 학습내용 중 정다각형은 초등학교, 중학교에서 볼록 정다각형을 중심으로 다루어지고 있는데, 본 연구에서는 학교에서 다루어지는 정다각형에 대한 학습내용을 기초지식으로 설정하고, 이를 기초로 정다각형 외연의 확장 과정을 체계적으로 탐색하였다. 특히 기하프로그램을 활용한 귀납적 탐구과정이 기하학습 내용 확장에 유의미한 방향을 제시해 줄 수 있다는 구체적 사례를 제시하였다. 본 연구결과를 통해, 정다각형에 대한 심화학습 자료 개발 및 기하 연구를 위한 바람직한 탐구 방향 제시가 기대되어진다.

• Geomechanics and Engineering
• /
• 제10권3호
• /
• pp.285-296
• /
• 2016

The investigation of stress wave propagation in a medium with initial stress has very important application in the field of engineering. However, the previous research less consider the influence of initial stress gradient on wave propagation. In the present paper, the governing equation of wave propagation in elastic continuum material with inhomogeneous initial stress is derived, which indicated that the inhomogeneous initial stress changed the governing equation of wave propagation. Additionally, the definite problem of wave propagation in material with initial stress gradient is verified by using mathematical physics method. Based on the definite problem, the elastic displacement-time relationship of wave propagation is explored, which indicated that the inhomogeneous initial stress changed waveform and relationship of displacement-time histories. Furthermore, the spall process of blasting wave propagation from underground to earth surface is simulated by using LS-DYNA.