• Journal of the Korean School Mathematics Society
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• v.17 no.2
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• pp.235-249
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• 2014

In this paper, teaching contents in area between Korea and Japan's first grade math textbooks are compared. Based on the results of this comparison, implications for improving our grade 1 math textbooks are obtained as follows. Firstly, when describing the configuration of two-digit numbers, it needs to be considered that, after the mathematical description of a concrete material representing two-digit numbers, then it should be processed mathematically. Secondly, with respect to the composition and decomposition of numbers, use of the expression of 'some number and some number' needs to be considered. Thirdly, when reading addition expression and subtraction expression with an equal sign, the way of reading them with terms 'sum' and 'difference' respectively needs to be reconsidered. Fourthly, use of the distinct expression for the supplementing situation and the merging situation respectively and use of the distinct expression for the removing situation and the comparing situation respectively need to be considered. Fifthly, the jump in representing the expression of subtraction of two numbers as the expression of the subtraction or mixed operation of three numbers to explain (some number)-(some number) with borrowing need to be resolved.

• Communications of the Korean Mathematical Society
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• v.21 no.3
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• pp.475-490
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• 2006

We give a way to obtain formulas for ${\pi}*{\psi}^{\kappa}_{n+1}$ in terms ${\psi}$ and ${\lambda}-classes$ where ${\pi}=\bar M_{g,n+1}{\rightarrow}\bar M_{g,n}(g=0,\;1,\;2)$ by the localization theorem. By using the formulas, we obtain Kontsevich-Manin type reconstruction theorems for $\bar M_{0,\;n}(\mathbb{R^m}),\;\bar M_{1,\;n},\;and\;\bar M_{2,\;n}$. We also (re)produce a lot of well-known relations in tautological rings, such as WDVV equation, the Mumford relations, the string and dilaton equations (g = 0, 1, 2) etc. and new formulas for ${\pi}*({\lambda}_g{\psi}^{\kappa}_{n+1}+...+{\psi}^{g+{\kappa}_{n+1}$.

• The Mathematical Education
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• v.63 no.2
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• pp.319-334
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• 2024

The purpose of this study was to reveal the discursive constructs of AI-based mathematical objects by analyzing how concrete objects used in the optimization content of AI mathematics textbooks are transformed into discursive objects through naming and discursive operation. For this purpose, we extracted concrete objects used in the optimization contents of five high school AI mathematics textbooks and developed a framework for analyzing the discursive constructs and discursive operations of AI-based mathematical objects that can analyze discursive objects. The results of the study showed that there are a total of 15 concrete objects used in the loss function and gradient descent sections of the optimization content, and one concrete object that emerges as an abstract d-object through naming and discursive operation. The findings of this study are not only significant in that they flesh out the discursive construction of AI-based mathematical objects in terms of the written curriculum and provide practical suggestions for students to develop AI-based mathematical discourse in an exploratory way, but also provide implications for the development of effective discursive construction processes and curricula for AI-based mathematical objects.

• Education of Primary School Mathematics
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• v.21 no.3
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• pp.289-307
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• 2018

Although mixed calculation of natural numbers is important in that it completes arithmetic calculation of natural numbers in elementary school, few studies have been conducted regarding its instruction methods. Given this, this study analyzed Korean mathematics textbooks (from the fifth textbooks to the 2009 revised textbooks) along with Japanese and Singaporean textbooks in terms of the parentheses and the order of operations regarding mixed calculation of natural numbers. The results of this study showed that there were differences in introducing the parentheses and representing them in an explicit way per textbooks. In the Korean textbooks, the order of operations was presented mostly with the real-life contexts but it was not always in a diagrammatic representation. In contrast, in the Singaporean textbooks, the order of operations was presented without the real-life contexts and the use of calculators was emphasized. In the Japanese textbooks, the order of operations was presented with the real-life contexts and a hierarchy of operations was emphasized. Based on these results, this study suggested several implications of textbook development and instructional methods regarding mixed calculations of natural numbers.

• School Mathematics
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• v.14 no.1
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• pp.45-64
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• 2012

The purpose of the present study was to investigate middle grades (Grade 5-7) mathematics teachers' knowledge of partitive fraction division. The data were derived from a part of 40-hour professional development course on fractions, decimals, and proportions with 13 in-service teachers. In this study, I attempted to develop a model of teachers' way of knowing partitive fraction division in terms of two knowledge components: knowledge of units and partitioning operations. As a result, teachers' capacities to deal with a sharing division problem situation where the dividend and the divisor were relatively prime differed with regard to the two components. Teachers who reasoned with only two levels of units were limited in that the two-level structure they used did not show how much of one unit one person would get whereas teachers with three levels of units indicated more flexibilities in solving processes.

• School Mathematics
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• v.16 no.3
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• pp.519-542
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• 2014

This study analyzed characteristics which emerged while 45 secondary school teachers observed a video clip about a statistics instruction. The aim of this study based on the analysis was to deduct implications in terms of the various means which would enhance teachers' knowledge in teaching statistics and assist in designing statistics education programs for teachers and professional development initiatives. To achieve this goal, this research firstly developed framework descriptors which provided this study with theoretical foundations to investigate what characteristics appeared in the teachers' observation. Secondly, this study probed the observation results from the teachers in the light of the framework. Therefore, some issues in the teacher education program for teaching statistics were thirdly identified in the categories of 'focus of instruction', 'role of the teacher and discourse' and 'data and technology' based on the analysis. This research inspires the elaboration of exactly what features effective statistics classes have through the framework descriptors and additionally the elucidation of essential matters relevant to statistics education on the basis of the issues.

• Journal of Educational Research in Mathematics
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• v.26 no.3
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• pp.565-581
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• 2016

Intuition in the mathematical problem solving has been stressed the importance with the logic because intuition is the cognition that give significant clue or idea to problem solving. Fischbein classified intuition by the origin; primary intuition and secondary intuition And he said the role of the personal experience and school education. Through these precedent research, we can understand the social influence. This study attempt to investigate social intuition model of Haidt, moral psychologist that has surfaced social property of intuition in terms of the mathematical problem solving. The major suggestions in problem solving and the education of intuition are followed. First, I can find the social property of intuition in the mathematical problem solving. Second, It is possible to make the mathematical problem solving model by transforming the social intuitionist model. Third, the role of teacher is important to give the meaningful experience for intuition to their students. Fourth, for reducing the errors caused by the coerciveness and globality of intuition, we need the education of checking their own intuition. In other words, we need intuition education emphasized on metacognition.

• Journal of Educational Research in Mathematics
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• v.20 no.3
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• pp.397-411
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• 2010

In this paper, definitions of biyoul and value of bi in elementary mathematics in Korea are critically analysed. And identity of halpunri is reviewed. Regarding biyoul, it is suggested that the use of term 'biyoul' is restricted to such cases when the quantity to be compared and the quantity to be a base have same measuring unit, without consider ing biyoul in terms of two numbers. it is suggested to use "the number which express how many times the quantity to be compared is contained by the quantity to be a base is called biyoul." as a definition of biyoul. It is suggested to use "value of bi A : B is A/B" as a definition of value of bi. Halpunri is a variation of halbunri, which is coined by putting hal, pun, and ri together in purpose of using in school mathematics. The tem1 corresponding halpunri is 'bohap', however, in this paper it is suggested to use halpunri after defining it instead of using bohap. In that halpunri is an acclimatized term of bohap, and considered as a biyoul not as a way to indicate biyoul, it is suggested to use "biyoul when the quantity to be a base is considered 10." as a definition of halpunri. It is suggested to see hal, pun, and ri are units for halpunri, and call decimal 0.1 expressing biyoul 1 hal, decimal 0.01 expressing biyoul 1 pun, decimal 0.001 expressing biyoul 1 ri respectively.

• The Mathematical Education
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• v.63 no.1
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• pp.63-83
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• 2024

The purpose of this study is to analyze the mathematical connection components of the tasks included in the trigonometric ratio unit of 3rd grade middle school textbook based on the 2015 revised mathematics curriculum and investigate teachers' perceptions and practical measures regarding these components. To this end, we analyzed the characteristics of mathematical connection tasks included in the trigonometric ratio units in nine types of 3rd grade middle school mathematics textbooks, and we conducted a questionnaire survey and interviews with one in-service math teachers in pre interview and with two in-service math teachers in this interview to investigate their perceptions and practical measures. As a result of the study, the number of tasks with external connection in the trigonometric ratio unit were less than those of internal connection. In addition, in terms of teachers' perceptions and practical measures, the perspective of analyzing tasks with mathematical connections varied depending on the teacher's perspective, and the practical measures varied accordingly. These findings are significant in that they reveal the relationship between mathematical tasks, teacher perceptions and measures to foster effectively students' mathematical connections.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.2
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• pp.727-746
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• 2018

The hash function RIPEMD-160 is a worldwide ISO/IEC standard and the hash function HAS-160 is the Korean hash standard and is widely used in Korea. On the basis of differential meet-in-the-middle attack and biclique technique, a preimage attack on 34-step RIPEMD-160 with message padding and a pseudo-preimage attack on 71-step HAS-160 without message padding are proposed. The former is the first preimage attack from the first step, the latter increases the best pseudo-preimage attack from the first step by 5 steps. Furthermore, we locate the linear spaces in another message words and exchange the bicliques construction process and the mask vector search process. A preimage attack on 35-step RIPEMD-160 and a preimage attack on 71-step HAS-160 are presented. Both of the attacks are from the intermediate step and satisfy the message padding. They improve the best preimage attacks from the intermediate step on step-reduced RIPEMD-160 and HAS-160 by 4 and 3 steps respectively. As far as we know, they are the best preimage and pseudo-preimage attacks on step-reduced RIPEMD-160 and HAS-160 respectively in terms of number of steps.