• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.9-15
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• 2011

The influence of the strain-rate on the superelastic behaviors of shape memory alloys (SMAs) wires is experimentally and numerically investigated. The one-dimensional SMA constitutive equations considering strain-rate effect is developed. The evolution of stress-strain curves of SMA wires is examined with various strain-rates. Results show that the superelastic behaviors of SMAs may significantly be changed depending on the variation of strain-rate.

• Journal for History of Mathematics
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• v.22 no.3
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• pp.273-292
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• 2009

According to historical commentators such as Newton and Einstein, bodily behaviors are causally explained by the geometrical structure of space-time whose existence analogous to that of material substance. This essay challenges this conventional wisdom of interpreting space-time geometry within both Newtonian and Einsteinian physics. By tracing recent historical studies on the interpretation of space-time geometry, I defends that space-time structure is a by-product of a more fundamental fact, the laws of motion. From this perspective, I will argue that the causal properties of space-time cannot provide an adequate account of the theory-change from Newtoninan to Einsteinian physics.

• The Mathematical Education
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• v.60 no.1
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• pp.77-110
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• 2021

In this study, a student participation-centered class based on student mathematical thinking as a the meaningful subject was called a student thinking-based math class. And as a way to support these classes, I paid attention to lesson design. For student thinking-based mathematics classes, it is necessary not only to anticipate student thinking and teacher feedback, but also to plan in advance how to properly arrange and connect expected student responses. The student thinking-based lesson design template proposed in this study is a modified three-step(introduction, main topic, summary) lesson design template. The reason for revising the existing design template is that it has limitation that it cannot focus on mathematical thinking. Using the conceptual framework of student thinking-based mathematics lesson as a lens, the difference between the three-step lesson design prepared by pre-service teachers and the students' thinking-based lesson design prepared by the same pre-service teachers was analyzed. As a result of planning lessons using the student thinking-based lesson design, more attention was paid to the cognitive and social engagement of students. In addition, emphasis was placed in the role of teachers as formative facilitator. This study is of significant in that it recognizes the importance of classes focusing on students' mathematical thinking and provides tools to plan math classes based on students' thinking.

• Communications of Mathematical Education
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• v.32 no.3
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• pp.275-296
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• 2018

The purpose of this study is to investigate the change of gaze and the change of the proof learning achievement after learning the analytic method for proof to mathematical gifted students using eye tracking technique. In order to complete the purpose of this study, a mixed method research was used, that is a combination of quantitative and qualitative research methods. Quantitative analysis was conducted based on the data obtained through the eye tracker, and qualitative analysis was also done using post interview data to make up for the quantitative analysis. The subjects of this study were 8 mathematical gifted 3rd grade middle school students in the gifted education center. The conclusions of this study are as follows. First, the learning of analysis leads to a change of gaze in the proof learning of students. The students, after learning the analysis, moved their gaze from the bottom to the top when solving the proof problem, and the occupancy rate of the gaze to the bottom of the proof was higher than the higher part. Second, the change of gaze caused by the learning of the analysis have a correlation with the achievement of the proof learning and it can be seen that the method learning improves the achievement of the proof learning of the students.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.96-101
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• 1999

Load model is very important to improve accuracy of stability analysis and load flow study in power systems. A power system bus is composed by various loads, and loads have different power consumption due to voltage/frequency changing. Thus the effect of voltage/frequency changing must he considered to load mxleling. In this research, ANN was used to construct component load moddel for more accurate load mxleling. Typical residential load was selected, and characteristics exrerimented on voltage/frequency changing. Acquired data used to construct the component ANN model, and aggregation method of component load model was presented based on component load model and composition rate. Furthennore, it's transfomlation method to the mathematical load model to he used at the traditional power system analysis soft wares was also presented.sented.

• Journal of Educational Research in Mathematics
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• v.23 no.2
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• pp.173-192
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• 2013

It may be replacement proofs with understanding and explaining geometrical properties that was a remarkable change in school geometry of 2009 revised national curriculum for mathematics. That comes from the difficulties which students have experienced in learning proofs. This study focuses on one of those difficulties which are caused by the forms of proofs: using letters for designating some sides or angles in writing proofs and understanding some long sentences of proofs. To overcome it, this study aims to investigate the applicability of Byrne's method which uses coloured diagrams instead of letters. For this purpose, the proofs of three geometrical properties were taught to middle school students by Byrne's visual method using the original source, dynamic representations, and the teacher's manual drawing, respectively. Consequently, the applicability of Byrne's method was discussed based on its strengths and its weaknesses by analysing the results of students' worksheets and interviews and their teacher's interview. This analysis shows that Byrne's method may be helpful for students' understanding of given geometrical proofs rather than writing proofs.

• Journal of the Korean School Mathematics Society
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• v.12 no.4
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• pp.509-522
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• 2009

This study aims to identify the effects of math education for the aged as part of active measures to the aging society with its growing elderly population which is one of the greatest changes in our society. Developing and disseminating materials of silver math with a role as a program for intelligent needs and physical and spiritual health of the aged presents evidence for development of more systemic and scientific method at this point of time when the importance of education of the aged increases to help the old enjoy qualitatively successful lives in later years in the perspective of lifelong education. The effectiveness of 'Silver Math' are explored by applying developed materials to the aged. Also, the influence of mathematical activities of learners capable of computing basic numbers on improvement of cognitive power are identified. Finally, the impact of 'Silver Math' on interaction with younger generations or communications is raised and the influence on brain activities is analyzed through examination of brain waves.

• The Mathematical Education
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• v.60 no.1
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• pp.1-19
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• 2021

This study investigates students' conceptions of fractions from a measurement approach while providing a technological environment designed to support students' understanding of the relationships between quantities and adjustable units. 13 third-graders participated in this study and they were involved in a series of measurement tasks through task-based interviews. The tasks were devised to investigate the relationship between units and quantity through manipulations. Screencasting videos were collected including verbal explanations and manipulations. Drawing upon the theory of semiotic mediation, students' constructed concepts during interviews were coded as mathematical words and visual mediators to identify conceptual profiles using a fine-grained analysis. Two students changed their strategies to solve the tasks were selected as a representative case of the two profiles: from guessing to recursive partitioning; from using random units to making a relation to the given unit. Dragging mathematical objects plays a critical role to mediate and formulate fraction understandings such as unitizing and partitioning. In addition, static and dynamic representations influence the development of unit concepts in measurement situations. The findings will contribute to the field's understanding of how students come to understand the concept of fraction as measure and the role of technology, which result in a theory-driven, empirically-tested set of tasks that can be used to introduce fractions as an alternative way.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.3
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• pp.579-598
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• 2011

In this study, the 2011 elementary school mathematics curriculum was analyzed compared to the 2007 elementary school mathematics curriculum with a focus on changes in specified learning topics. First, the topics which are dealt with in the 2011 curriculum were critically discussed. Second, prominent features which can be found in learning topics in 2011 curriculum were found. The following three conclusions which can be obtained from above analyzed results were presented. First, system for curriculum development is necessary to supplement. The process of draft development for public hearing and final curriculum development is not exposed anywhere. It is necessary to clean up and disclose this process in order to study and develop next curriculum. Second, it is necessary to modify the way of stating in curriculum. it is necessary to specify and use the expressions to some extent the meaning of which are not sufficiently established and the meaning of which are ambiguous. Third, the achievement standards set by 2011 curriculum needs to be consistent. The principles for stating achievement standards are necessary. it is necessary to review the link between elementary and middle school curriculum is well-made.

• School Mathematics
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• v.19 no.4
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• pp.639-661
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• 2017

The purpose of this study is to investigate the relationship between the distance function average speed and the speed function. Particularly, in this study, we investigate the process of constructing the speed function in the distance function (irrational function, exponential function) which is difficult to weaken the argument in the denominator. In this process, students showed various anxieties and expressions about the procedural knowledge that they constructed first. In particular, if student B can not explain all the knowledge he already knows in this process, he showed his reflection on the process of calculating the differential coefficient. This study adds an understanding of the calculation method of students in differential coefficient learning. In addition, it is meaningful that the students who construct procedural knowledge at the time of calculating the differential coefficient have thought about how to provide opportunities to reflect on the procedure they constructed.