• 제목/요약/키워드: mathematical material

검색결과 587건 처리시간 0.021초

알지오매스 기반 수업이 수학적 문제해결력 및 태도에 미치는 효과: 초등학교 5학년 '직육면체' 단원을 중심으로 (The Effect of Mathematics Classes Using AlgeoMath on Mathematical Problem-Solving Ability and Mathematical Attitude: Focusing on the 'Cuboid' Unit of the Fifth Grade in Elementary School)

  • 이승동;이종학
    • 과학교육연구지
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    • 제48권1호
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    • pp.47-62
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    • 2024
  • 본 연구의 목적은 초등학교 5학년을 대상으로 알지오매스를 활용한 수업이 학생들의 수학적 문제해결력 및 수학적 태도에 미치는 효과를 알아보는 데 있다. 이를 위해서 초등학교 5학년 수학 교과서의 '직육면체'를 재구성한 알지오매스 기반 교수·학습자료를 사용해서 총 8차시의 실험 수업을 실시하였다. 그리고 실험 수업의 전후에 수집한 양적 자료들을 통계적으로 분석하였고, 또한 알지오매스를 활용한 실험 수업의 장면을 구체적으로 제시함으로써, 수학적 문제해결력과 태도의 측면에서 공학을 활용한 수업의 효과와 실제를 알아보았다. 본 연구의 결과는 다음과 같다. 첫째, 수학적 문제해결력검사에서 실험집단과 비교집단은 유의수준 0.05에서 유의미한 차이가 있었다. 즉, 알지오매스를 활용한 수업은 수학적 문제해결력의 신장에 효과가 있는 것으로 나타났다. 둘째, 수학적 태도 검사에서 실험집단과 비교집단은 유의수준 0.05에서 유의미한 차이가 없었지만, 수학적 태도의 모든 하위 요소들에 대해서 실험집단이 비교집단보다 평균 점수가 상승한 것으로 나타났다.

일정한 납기구간을 갖는 유연생산시스템에서의 AGV 경로에 관한 연구 (Automated guided vehicle routing for the fixed-interval deliveries of a flexible manufacturing system)

  • 최현선;유융석;노인규
    • 산업경영시스템학회지
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    • 제26권2호
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    • pp.68-74
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    • 2003
  • Modem automated manufacturing processes employ automated guided vehicles(AGVs) for material handling, which serve several machining centers(MCs) in a factory. Optimal scheduling of AGVs can significantly help to increase the efficiency of the manufacturing process by minimizing the idle time of MCs waiting for the raw materials. In this paper, we will analyse the requirements for an optimal schedule and then provide a mathematical framework for an efficient schedule of material delivery by an AGV. With this model, the optimal number of MCs to be utilized will also be determined. Finally, the material delivery schedule employing multiple journeys to the MCs by the AGV will be carried out. Through rigorous analysis and simulation experiments, we shall show that such a delivery strategy will optimize the overall performance.

Experimental studies on the material properties of high-strength bolt connection at elevated temperatures

  • Li, Guo-Qiang;Yin, Ying-Zhi;Li, Ming-Fei
    • Steel and Composite Structures
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    • 제2권4호
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    • pp.247-258
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    • 2002
  • The high-temperature material properties of steel are very important to the fire resistance analysis of high-strength bolt connections. This paper reports on the results of the experimental studies on the high-temperature properties of 20 MnTiB steel which is widely used in high-strength bolts, and the friction coefficient of 16Mn steel plates at elevated temperature which is a necessary parameter for bolted frictional connection analysis. The test data includes yield strength, limit strength, modulus of elasticity, elongation and expansion coefficient of 20MnTiB steel at elevated temperature, and the friction coefficients between two 16Mn steel plates under elevated temperatures and after cooling. Based on the data from the tests, the mathematical models for predicting the mechanical properties of 20MnTiB steel and friction coefficients of 16Mn steel plates have been established.

통계적 기법을 이용한 전력 케이블 절연층(XLPE)의 수명 예측 (Life Expectancy for Power Cable Insulation(XLPE) Using Statistical Method)

  • 이승엽;조대희;이인호;박완기
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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    • pp.57-61
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    • 1999
  • Electrical stress makes insulating materials aged finally resulting in the dielectric failure. It becomes more and more important to recognize the degree of aging and the life time of the insulating materials since it is directly concerned with the reliability of the insulation system. In this paper, the life time of the Cross-linked Polyethylene(XLPE), the insulation layer in the 154kV-grade power cable, is expected and calculated using statistical and mathematical methods. The simulated results are compared with experimental ones and the life exponent of the material is obtained.

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전도성 접착제의 열경화 응력에 대한 해석 (Thermal Ratchetting of the Conductive Adhesives Joints Subjected to the Thermal Cycles)

  • 박주혁;서승호
    • 한국마이크로전자및패키징학회:학술대회논문집
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    • 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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    • pp.208-213
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    • 2002
  • When a thermoset conductive adhesive joints are subjected to the thermal cycles, the thermal stresses are developed around the joints. Most of in-plane, hi-axial components of these residual stresses induces large tensile peel stresses and weakens adhesive joints. Also these stresses vary with thermal cycles, and result in thermal fatigue loading and debonding propagation. In this study, the thermal ratchetting effect in conductive adhesive joints are evaluated by the finite element analysis with the viscoelastic material model. In order to Investigate the relationship between thermal ratchetting and glass transition temperature, the mathematical material model has been developed experimentally by dynamic mechanical analysis. These material models are implemented to the finite element analysis with thermal loading cycles. And the stress profiles around the conductive adhesive joints are calculated. It has been observed that the thermal ratchetting occurs when the maximum temperature of thermal cycles is above the glass transition temperature. The peel and shear stress components increase as the thermal loading time increases. This will contributes to thermal fatigue fracture of the joints.

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Synthesis Peculiarities of Nanocomposite Structures by Abrasive-reaction Interactions

  • Ketegenov, T.;Tyumentseva, O.;Kasymbecova, D.;Korobova, N.;Katranova, Z.;Urakaev, F.
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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    • pp.643-644
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    • 2005
  • New methods of nano-sized material and composite coating preparations have been considered on the base of mathematical model of abrasion-reaction interaction of milling and grinding bodies in planetary centrifugal mill. The essence of the method is the abrasive and oxidative wear of the milling bodies and amorphous (better inert) additives. Interactions between them has been supplied the necessary impulse of pressure and temperature on the impact-frictional contacts and promoted chemical processes. The offered method can find application for such processing as sintering and geological minerals opening.

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Effects of porosity models on static behavior of size dependent functionally graded beam

  • Hamed, Mostafa A.;Sadoun, Ayman M.;Eltaher, Mohamed A.
    • Structural Engineering and Mechanics
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    • 제71권1호
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    • pp.89-98
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    • 2019
  • In this study, the mechanical bending behaviors of functionally graded porous nanobeams are investigated. Four types of porosity which are, the classical power porosity function, the symmetric with mid-plane cosine function, bottom surface distribution and top surface distribution are proposed in analysis of nanobeam for the first time. A comparison between four types of porosity are illustrated. The effect of nano-scale is described by the differential nonlocal continuum theory of Eringen by adding the length scale into the constitutive equations as a material parameter comprising information about nanoscopic forces and its interactions. The graded material is designated by a power function through the thickness of nanobeam. The beam is simply-supported and is assumed to be thin, and hence, the kinematic assumptions of Euler-Bernoulli beam theory are held. The mathematical model is solved numerically using the finite element method. Numerical results show effects of porosity type, material graduation, and nanoscale parameters on the static deflection of nanobeam.

Computational mathematical modeling of the nonlinear vibration characteristics of AFG truncated conical nano pipe based on the nonlocal strain gradient theory

  • Zhang, Ruihua;Cao, Yiqing
    • Steel and Composite Structures
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    • 제42권5호
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    • pp.599-615
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    • 2022
  • In the present paper, the numerical dynamic analysis of a functionally graded nano-scale nonuniform tube was investigated according to the high-order beam theory coupled with the nonlocal gradient strain theory. The supposed cross-section is changed along the pipe length, and the material distribution, which combines both metal and ceramics, is smoothly changed in the pipe length direction, which is called axially functionally graded (AFG) pipe. Moreover, the porosity voids are dispersed in the cross-section and the radial pattern that the existence of both material distribution along the tube length and porosity voids make a two-dimensional functionally graded (2D-FG) truncated conical pipe. On the basis of the Hamilton principle, the governing equations and the associated boundary conditions equations are derived, and then a numerical approach is applied to solve the obtained equations.

열경화성 수지 재료를 이용한 광학 렌즈 제조공정에서 렌즈 변형에 대한 수축률이 영향에 관한 연구 (A Study on the Effect of Shrinkage on Lens Deformation in Optical Lens Manufacturing Process Using Thermosetting Resin Material)

  • 박시환
    • Design & Manufacturing
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    • 제16권3호
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    • pp.9-15
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    • 2022
  • In order to reduce the manufacturing costs of the glass lens, it is necessary to manufacture a lens using a UV curable resin or a thermosetting resin, which is a curable material, in order to replace a glass lens. In the case of forming a lens using a thermosetting material, it is necessary to form several lenses at once using the wafer-level lens manufacturing technologies due to the long curing time of the material. When a lens is manufactured using a curable material, an error in the shape of the lens due to the shrinkage of the material during the curing process is an important cause of defects. The major factors for these shape errors and deformations are the shrinkage and the change of mechanical properties in the process of changing from a liquid material during curing to a solid state after complete curing. Therefore, it is necessary to understand the curing process of the material and to examine the shrinkage rate and change of physical properties according to the degree cure. In addition, it is necessary to proceed with CAE for lens molding using these and to review problems in lens manufacturing in advance. In this study, the viscoelastic properties of the material were measured during the curing process using a rheometer. Using the results, Rheological investigation of cure kinetics was performed. At the same time, The shrinkage of the material was measured and simple mathematical models were created. And using the results, the molding process of a single lens was analyzed using Comsol, a commercial S/W. In addition, the experiment was conducted to compare and verify the CAE results. As a result, it was confirmed that the shrinkage rate of the material had a great influence on the shape precision of the final product.

골판지를 이용한 완충 포장재의 물리적 특성에 관한 연구 (The Analysis of Cushioning Properties of Corrugated Cushion)

  • 최승진;신중민
    • 한국포장학회지
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    • 제12권1호
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    • pp.35-40
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    • 2006
  • Cushioning systems, which are cushion material and its designed configuration, are important to protect fragile items since they act as buffers between the impact force and the fragile product. As cushioning materials, several plastic foams are commonly used in industry. However, the utilization of the plastic material has been causing a solid waste problem and pollution. Thus, as an alternative cushion material to the plastic foams, a corrugated cushion, which is considered environmentally friendly and cheap material, was put into drop tests and its impact shock attenuation was investigated. Flat and free drop data were recorded and compared to the dynamic shock of EPS cushion. In addition, the mathematical model of the shock attenuation of the corrugated cushion was developed. The result showed that the corrugated cushion gave an excellent protection for items that were subjected to the limited number of drops. There was no significant difference of the shock absorbing ability between the EPS and corrugated cushions. Energy density model of cushioning material successfully explained the mechanical behavior and fatigue of the corrugated cushions.

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