• Journal of Educational Research in Mathematics
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• v.10 no.1
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• pp.139-159
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• 2000

The experimental software such as Cabri II, The Geometer's Sketchpad, etc. provides dynamic environment which construct and explore geometric objects interactively and inductively. It has the effects on mathematics itself differently from other technologies that are used in instruction. What is its characteristics\ulcorner What are the educational implication of it for the learning of geometry\ulcorner How is mental reasoning of geometric problems changed by transformation of the means of representation and the environment to manipulate them\ulcorner In this study, we answer these questions through the review of the related literatures and the analysis of textbooks, teaching materials using it and curricular materials. Also, we identify implications about how the criteria for choosing geometic content and the ways of constructing context, for orchestrating the students' exploration with the secondary geometry curriculum, can be changed.

• Transactions of Materials Processing
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• v.19 no.2
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• pp.113-119
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• 2010

Hydroforming is the technology that utilizes hydraulic pressure to form tube or sheet materials into desired shapes inside die cavities. Tube hydroforming provides a number of advantages over the conventional stamping process, including fewer secondary operations, weight reduction, assembly simplification, adaptability to forming of complex structural components and improved structural strength. In many case, hydroformed parts have to be structurally joined at some point. Therefore it is useful if the hydroformed automotive parts can be given a localized attachment flange. In this study for the numerical process design FE analysis was performed with DYNAFORM 5.5. Die parting angle and circumferential expansion ratio was optimized. With optimized condition, bulge and hydroforming experiments to form flange were performed. Forming characteristic at various pressure conditions was analyzed and optimized internal pressure condition was evaluated. The results show that flanged parts can be successfully produced by tube hydroforming process.

• The Mathematical Education
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• v.42 no.4
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• pp.465-480
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• 2003

The main purpose of this work is to propose programs of mathematics education and mathematics history courses for the department of mathematics education of teacher training universities. Foundation of Mathematics Education, Mathematics Teaching and Learning Theories, Mathematics Problem Solving, Analysis and Evaluation of Mathematics Teaching Materials and Mathematics History are discussed in this article.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.6
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• pp.284-289
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• 2020

Since the dissimilar bonded interface usually consists of intermetallic compounds (IMCs) layer and cracks, their mechanical and electrical properties can be influenced by microstructure at interface between two different metals. In this study, the friction welded Cu-Al busbar, which is widely used to connect a secondary battery and their component, is selected to analyze the influence of interfacial characteristic on their tensile strength and electric conductivity. Then, the electrical characteristics of Cu busbar and Cu-Al busbar were investigated by thermal flow analysis and temperature rise test. In addition, the relationship between the maximum saturation temperature and the electrical conductivity were discussed in terms of interfacial characteristics of the friction welded Cu-Al busbar.

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1381-1389
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• 2019

Stress corrosion cracking (SCC) widely found in both primary and secondary sides of steam generator (SG) tubing in pressurized water reactors (PWR) has become an important safety issue. Using eddy-current tests (ECTs), non-destructive evaluations are performed for the integrity management of SG tubes against intergranular SCC. To enhance the reliability of ECT, this study investigates the effects of oxide films on ECT's detection capabilities for SCC in laboratory-degraded SG tubing in high temperature and high pressure aqueous environment.

• Educational Technology International
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• v.23 no.1
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• pp.97-127
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• 2022

With the recent advancement of technology, there has been an increase in professional development activities, including teachers using blogs to share practical knowledge and reflect on teaching and learning. This study was conducted to identify the contents of practical knowledge shared through the K-12 teachers' blogs. To achieve the research objective, 70,571 blog posts were collected from 329 blogs of K-12 teachers in Korean and analyzed using text mining techniques. The results of the study are as follows. First, practical knowledge sharing activities using teacher blogs have increased. Teachers posted a lot of blogs during the semester. Second, primary school teachers share various curriculum activities, reflections on project classes, class management, opinions related to education, and personal. Third, secondary school teachers share summaries and reviews of curriculum, materials related to college entrance exams, various instructional materials, opinions related to education, and personal experiences on their blogs. This study suggested that blogs are widely used as a venue for sharing practical knowledge of teachers, and that blogs can be a useful way to develop professionalism.

• Applied Microscopy
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• v.52
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• pp.2.1-2.6
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• 2022

With the lightening of the mobile devices, thinning of electrolytic copper foil, which is mainly used as an anode collection of lithium secondary batteries, is needed. As the copper foil becomes ultrathin, mechanical properties such as deterioration of elongation rate and tear phenomenon are occurring, which is closely related to microstructure. However, there is a problem that it is not easy to prepare and observe specimens in the analysis of the microstructure of ultrathin copper foil. In this study, electron backscatter diffraction (EBSD) specimens were fabricated using only mechanical polishing to analyze the microstructure of 8 ㎛ thick electrolytic copper foil in plane view. In addition, EBSD maps and transmission electron microscopy (TEM) images were compared and analyzed to find the optimal cleanup technique for properly correcting errors in EBSD maps.

• Proceedings of the Korean Vacuum Society Conference
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• 1996.02a
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• pp.161-161
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• 1996

Recently, the role of the surface analysis on the development of advanced materials has become larger and larger as the surface compositions of these materials is the key of their performances. Especially three techniques, Auger electron spectroscopy, X- ray photoelectron spectroscopy and secondary ion mass spectroscopy are widely used in technology fields. However, because of the relatively short history of these techniques(thirty years or so), there has been no accumulation of data commonly available, physical parameters for analysis have not been established and there has been no standard data. With these background, the VAMAS projects which aims to standardize the manner in the field of these techniques has started in 1982 at Versailles Summit. Along the projects, we have conducted the international collaborating study on the sharing of spectral data. In 1994, the Science and Technology Agency of Japan began the project on computer network, on which our fruits from the study on spectral data sharing is boarded.(omitted)mitted)

• Journal of the Korean School Mathematics Society
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• v.9 no.3
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• pp.317-345
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• 2006

The purpose of this paper is to provide readers related to mathematics education with information and guidelines on 'Teaching and Learning Materials for Differentiated Instruction in Mathematics'. This paper is generally comprised of two parts. The one part is basically focused on understanding the meaning of differentiated education. The focus of the other part is on developing differentiated instructional materials for mathematics, according to the following procedures: 1. Analyzing the current differentiated mathematics curriculum and textbooks 2. Drawing a framework for developing the differentiated teaching and learning materials, and planning the procedure of developing the materials in detail. 3. Developing, checking, and revising the materials 4. Proposing how to utilize the materials effciently and effectively in class

• Journal of The Korean Association For Science Education
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• v.5 no.2
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• pp.81-88
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• 1985

The purpose of the study was to establish a new view of textbook which may contribute to the abolishment of the instruction mainly based on the only textbook and to the promotion of creativities of students. We first reviewed science textbooks and related teaching-learning materials of foreign countries with emphasis on the relationship among textbook and teaching-learning materials and practical use of them. In western countries the roles of traditional textbook has been changed. That is, various kinds of materials such as reading book, work-book, worksheet, experimental guidebook, filmstrips are used to raise effect of instruction besides of traditional type of textbook. Secondary, we identified the problems related to the science textbook-view of textbook, textbook contents, practical use of textbook-through opinion survey administered to principals akd teachers of elementary schools. The results of the survey are as follows; Concerning the view of textbook, most teachers did not recognize textbook as an absolute materials. They thought that textbook contents could be taught reorganized according to their judgements. On the contrary, teachers responded to the question of whether or not they follow contents of textbook as they are presented in it were approximately 30%. Further, more than 75% of them have seldom used instructional materials except textbooks. In order to revise the problems of our present textbook as stated above, a new view of textbook should be established. We, above all, established 4 basic premises for searching a new view of textbook. 1) Textbook should not be considered as the only material but as being at the center of various teaching -learning materials. 2) The importance of textbook should be illustrated Among Curriculum, textbook and related teaching-learning materials, instruction and evaluation. 3. Textbook contents should not be regarded as definitely fixed or absolute ones. 4. Human being can understand environment more fully by commanding his swnsory organ multilaterally. Under these premises we disscussed about curriculum and textbook, textbook, and instruction, akd evaluation method.