• Journal of the Korean School Mathematics Society
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• v.13 no.1
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• pp.1-21
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• 2010

This paper analyzed the contents and instructional methods of various plane figures presented mainly in a series of elementary mathematics textbooks on the basis of the analysis of related contents in the 2007 revised national mathematics curriculum. As such, this paper provided detailed analyses of how textbooks would implement the vision and intention of the curriculum, how the definition of each plane figure in the textbooks might be different from its mathematical definition, and how textbooks would introduce each plane figure. It is expected that the issues and suggestions stemming from this analysis will be informative in designing new instructional materials.

• Communications of Mathematical Education
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• v.21 no.3
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• pp.467-482
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• 2007

In this paper, we surveyed the attitudes of engineering students in 6 universities in Chungcheong area to mathematics by 5-scale degrees and performed a comparative analysis of the results. The results revealed a number of meaningful points which should be applied to college mathematic education. On the basis of the results of the analysis, we made the following suggestions; 1) It is necessary to pay much attention to the students who have insufficient math ability 2) Special teaching methods are required for Freshman engineering students 3) Practical teaching strategies should be developed for engineering students that are based on the research on their math background 4) We should develop more materials in the area of mathematical concept image 5) More attention should be paid to the relation between math concepts and engineering concepts. Besides the above suggestions, we proposed that more research about students' math background and attitudes should be conducted for more efficient college math education.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.6 no.1
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• pp.1-11
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• 2000

In optimum design of packaging container for bulk materials, minimum board area, compression performance and distribution efficiency must be considered. In this study, mathematical models for minimum board area (RMA), compression strength (CS) and maximum compression strength per unit board area (MCSA) of container as algorithm for optimum design of packaging conatiner for bulk materials were developed as follows : RMA=f(V,D), ${\alpha}_{RMA}=f(V,D)$, MCSA=f(V,D), and ${\alpha}_{MCSA}=f(V,D)$. In order to develop these models, compression test according to various dimensions of container and response surface analysis for minimum board area, compression strength, and maximum compression strength per unit board area of container were carried out. In developed models, volume and depth of container were principal independent variables. Through the verified results for these models, optimum design of packaging container on the design conditions and limit conditions was possible. These models might be used in developing optimum design software of packaging container for bulk materials.

• Structural Engineering and Mechanics
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• v.23 no.1
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• pp.63-74
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• 2006

In this paper, the scattering of harmonic elastic anti-plane shear waves by two collinear cracks in functionally graded materials is investigated by means of nonlocal theory. The traditional concepts of the non-local theory are extended to solve the fracture problem of functionally graded materials. To overcome the mathematical difficulties, a one-dimensional non-local kernel is used instead of a two-dimensional one for the anti-plane dynamic problem to obtain the stress field near the crack tips. To make the analysis tractable, it is assumed that the shear modulus and the material density vary exponentially with coordinate vertical to the crack. By use of the Fourier transform, the problem can be solved with the help of a pair of triple integral equations, in which the unknown variable is the displacement on the crack surfaces. To solve the triple integral equations, the displacement on the crack surfaces is expanded in a series of Jacobi polynomials. Unlike the classical elasticity solutions, it is found that no stress singularities are present at crack tips.

• Restorative Dentistry and Endodontics
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• v.43 no.4
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• pp.48.1-48.13
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• 2018

Objectives: To analyze the influence of thickness and incisal extension of indirect veneers on the stress and strain generated in maxillary canine teeth. Materials and Methods: A 3-dimensional maxillary canine model was validated with an in vitro strain gauge and exported to computer-assisted engineering software. Materials were considered homogeneous, isotropic, and elastic. Each canine tooth was then subjected to a 0.3 and 0.8 mm reduction on the facial surface, in preparations with and without incisal covering, and restored with a lithium disilicate veneer. A 50 N load was applied at $45^{\circ}$ to the long axis of the tooth, on the incisal third of the palatal surface of the crown. Results: The results showed a mean of $218.16{\mu}strain$ of stress in the in vitro experiment, and $210.63{\mu}strain$ in finite element analysis (FEA). The stress concentration on prepared teeth was higher at the palatal root surface, with a mean value of 11.02 MPa and varying less than 3% between the preparation designs. The veneers concentrated higher stresses at the incisal third of the facial surface, with a mean of 3.88 MPa and a 40% increase in less-thick veneers. The incisal cover generated a new stress concentration area, with values over 48.18 MPa. Conclusions: The mathematical model for a maxillary canine tooth was validated using FEA. The thickness (0.3 or 0.8 mm) and the incisal covering showed no difference for the tooth structure. However, the incisal covering was harmful for the veneer, of which the greatest thickness was beneficial.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1989.10a
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• pp.34-39
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• 1989

Recent trends in design standards development have encouraged the use of probabilistic limit sate design concepts. Reliability analysis adopted in those advanced countries have the potentials that they afford for symplifying the design Process arid placing it on a consistent reliability based for various construction materials. This study is proposed in the reliability analysis of plane frame structures using second-order moment method(Level-II they). Lind-Hasofer's minimum distance method is use in the derivation of an mathematical algorithm as well as an determination of Correlation cofficients, reliability index and total reliability index depending on the multiple failure modes. In addition. This study is employed as a practical tool for the approximate reliability analysis. Results of the numerincal analysis showed that the difference between the reliability index of the failure probability of the multiple failure modes and the total reliability index of the failure probability with the simultaneous failure modes deviated nearly 3∼10% depending on tile performance functions.

• Transactions of Materials Processing
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• v.10 no.1
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• pp.3-14
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• 2001

Hydroforming is the technology using hydraulic pressure and forming sheet or tube metals to desired shape in a die cavity. lt can be characterized as tube hydroforming and sheet hydroforming depending on the shape of used blank. Due to its prcess-related benefits, this production technology has been remarkably noticed for great potential for feasible applications and recently gained great attraction from many industrials including automotive and non-automotive. This Paper analyzed the tube and the welded blank hydroforming process and compared formability of the processes for automotive engine mount bracket. The mathematical analysis was performed by using the dynamic explicit finite element code, PAM-STAMP. In tube hydroforming, bending, springback, and forming analysis were carried out and the effect of mandrel and axial feeding were examined. In welded blank hydroforming, pressure curve history is determined and the results of forming analysis were evaluated by the comparison of experimental results in the aspects of deformed shape and thickness distribution.

• Communications of Mathematical Education
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• v.37 no.2
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• pp.183-197
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• 2023

Mathematical listening ability(MLA) refers to the capability to listen to speech languages that contain mathematical principles and concepts and understand their meanings, distinguishing it from daily life and listening in other subject classes. In this study, I investigated 834 elementary school students' MLA adapting a MLA survey items. Through the statistical analysis results of the survey, I confirmed that students' MLA had a significant correlation with gender, grade, and school location. Female students' MLA was statistically significantly higher than that of male students. MLA increased with grade and then decreased again in 6th grade. In addition, students' MLA was statistically significant differences according to the location of the school. The results of this study might be used as the basis for follow-up research and development of teaching and learning materials related to MLA.

• Communications of Mathematical Education
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• v.21 no.2 s.30
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• pp.125-152
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• 2007

When we teach mathematics in college, we find a lot of mistakes, fallacies and flaws in the solution of the students. In this paper, we presented a variety of examples of mistakes and fallacies, including wrong proofs, misinterpreted definitions and the mistaken use of theory. The examples, taken from different classes and subjects, are based on our own experience of teaching mathematics. As the previous research argued, such mistakes, fallacies and flaws should be considered as natural phenomena in the students' progress and should be analyzed systematically for the more effective education. By providing a wide-ranging examples of mistakes and fallacies, and detailed analyses of them, we emphasized the significance of the analysis of mistakes and fallacies and proposed that more careful attention should be paid on the collection and development of teaching materials in the area of mistake and fallacy analysis. We hope that this study would be a meaningful contribution to the teaching of mathematics in college.

• Advances in nano research
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• v.13 no.1
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• pp.1-12
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• 2022

The existence of active material in the environment causes the small-scale systems to be sensitive to the actual environment. Carbon dioxide is one of the active materials that exists a lot in the air conditions of the living environment. However, in some applications, the carbon dioxide-coated is used to improve the performance of systems against the destructive factors such as the corrosion; nevertheless, in the current research, the stability analysis of a carbon dioxide capture mechanism-coated beam is investigated according to the mathematical simulation of a rectangular composite beam utilizing the modified couple stress theory. The composite mechanism of carbon dioxide trapping is made of a polyacrylonitrile substrate that supports a cross-link polydimethylsiloxane gutter layer as the carbon dioxide mechanism trapping. Three novel types of carbon dioxide trapping mechanism involving methacrylate, poly (ethylene glycol) methyl ether methacrylate, and three pedant methacrylates are considered, which were introduced by Fu et al. (2016). Finally, according to introducing the methodology of carbon dioxide (CO₂) trapping, the impact of various effective parameters on the stability of composite beams will be analyzed in detail.