• 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.

• Education of Primary School Mathematics
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• v.25 no.3
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• pp.251-278
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• 2022

The purpose of this study is to obtain implications for mathematical education by analyzing how the multiplication and division of decimal numbers are presented in the elementary mathematics textbooks in Korea, Japan, Singapore, and Finland. Compared to the fact that students often have misconceptions about multiplication and division of decimal numbers, there have been not many comparative studies in recent elementary mathematics textbooks. For this study, we selected elementary mathematics textbooks those are widely used in Japan, Singapore, and Finland along with Korean elementary mathematics textbooks. We chose the textbooks because the students in the selected countries have scored high in international achievement studies such as TIMSS and PISA. The analysis was examined in terms of elementary mathematics curriculum related to multiplication and division of decimal numbers, introduction and content, real-life situations, use of visual models, and formalization methods of algorithms. As a result of the study, the mathematics curricula related to multiplication and division of decimal numbers includes estimation in Korea and Finland, while Japan and Singapore emphasize real-life connections more, and Finland completes the operations in secondary schools. The introduction and content are intensively provided in a short period of time or distributed in various grades and semesters. The real-life situations are presented in a simple sentence format in all countries, and the use of visual models or formalization of algorithms is linked to the operations of natural numbers in unit conversions. Suggestions were made for textbook development and teacher training programs.

• School Mathematics
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• v.19 no.1
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• pp.209-228
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• 2017

Understanding decimal numbers is important in mathematics as well as real-life contexts. However, lots of students focus on procedures or algorithms of decimal numbers without understanding its meanings. This study analyzed teaching method related to decimal numbers in a series of mathematics textbooks of Korea, Japan, Singapore and the US. The results showed that three countries except Japan introduced the decimal numbers as another name of fraction, which highlights the relation between the concept of decimal numbers and fractions. And limited meanings of decimal numbers were shown such as 'equal parts of a whole' and 'measurement'. Especially in the korean textbooks, relationships between the decimals were dealt instrumentally and small number of models such as number lines or $10{\times}10$ grids were used repeatedly. Based these results, this study provides implications on what and how to deal with decimal numbers in teaching and learning decimal numbers with textbooks.

• Journal of the Chungcheong Mathematical Society
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• v.27 no.2
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• pp.183-203
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• 2014

We examine fundamental units of quadratic function fields from continued fraction of $\sqrt{D}$. As a consequence, we give another proof of geometric analog of Ankeny-Artin-Chowla-Mordell conjecture and bounds for class number, and study real quadratic function fields of minimal type with quasi-period 4.

• Kyungpook Mathematical Journal
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• v.51 no.3
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• pp.345-352
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• 2011

In this article we introduce the fuzzy real valued double sequence spaces $_2{\ell}^F$ (p) where p = ($p_{nk}$) is a double sequence of bounded strictly positive numbers. We study their different properties like completeness, solidness, symmetricity, convergence free etc. We prove some inclusion results also.

• Journal of applied mathematics & informatics
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• v.40 no.5_6
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• pp.1167-1179
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• 2022

In this paper, we obtain some subsets of real numbers (ℝ) on which a fractional part function is defined as a real-valued continuous function. This gives rise to the analysis of the continuous properties of the fractional part function as a real-valued function. The analysis of fractional part function is helpful in the study of the dynamics of circle.

• Journal of applied mathematics & informatics
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• v.34 no.5_6
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• pp.369-382
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• 2016

In this paper, we investigate the global behavior of the solutions of the difference equation $x_{n+1}=\frac{A+Bx_{n-2k-1}}{C+D\prod_{i=l}^{k}x_{n-2i}^{m_i}}$, n=0, 1, ..., with non-negative initial conditions, the parameters A, B are non-negative real numbers, C, D are positive real numbers, k, l are fixed non-negative integers such that l ≤ k, and m_i, i=l, k are positive integers.

• Journal of Educational Research in Mathematics
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• v.11 no.1
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• pp.223-238
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• 2001

Decimal fractions are the practical system of notations representing real numbers. The set of decimal fractions with the definition of comparison of decimal fractions and the identification of their double representations is essentially the field of real numbers. Therefore, we have to clarify the concept of decimal fractions. However, there are problematics that the aquisition of the concept of decimal fractions is not easy. In this paper, we attempt to eradicate the problematics relevant to the acquisition of decimal fractions discussed above and find the desirable direction of instruction of meaning for mathematical symbols: The case of decimal fractions. In J. Hiebert & decimal fractions. First of all, we clarify the essence of them - ratio, operator and linearity. And we compare and analyse the theories about decimal fractions of Resnick, Drexel, Brousseau and Hiebert and the contents of texts about decimal fractions in Korea. Finally, we suggest the efficient instruction methods which are faithful to the essence of decimal fractions and choose some methods among them to plan the classroom instruction and implement the methods in the classroom.

• Korean Journal of Mathematics
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• v.4 no.1
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• pp.45-49
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• 1996

Let $F_0$ be the maximal real subfield of $\mathbb{Q}({\zeta}_q+{\zeta}_q^{-1})$ and $F_{\infty}={\cup}_{n{\geq}0}F_n$ be its basic $\mathbb{Z}_p$-extension. Let $A_n$ be the Sylow $p$-subgroup of the ideal class group of $F_n$. The aim of this paper is to examine the injectivity of the natural $mapA_n{\rightarrow}A_m$ induced by the inclusion $F_n{\rightarrow}F_m$ when $m>n{\geq}0$. By using cyclotomic units of $F_n$ and by applying cohomology theory, one gets the following result: If $p$ does not divide the order of $A_1$, then $A_n{\rightarrow}A_m$ is injective for all $m>n{\geq}0$.

• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.217-230
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• 2017

In this paper we deal with the difference equation $$y_{n+1}=\frac{ay_{n-1}}{by_ny_{n-1}+cy_{n-1}y_{n-2}+d}$$, $$n{\in}\mathbb{N}_0$$, where the coefficients a, b, c, d are positive real numbers and the initial conditions $y_{-2}$, $y_{-1}$, $y_0$ are nonnegative real numbers. Here, we investigate global asymptotic stability, periodicity, boundedness and oscillation of positive solutions of the above equation.