• Journal of the Korean School Mathematics Society
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• v.13 no.3
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• pp.381-395
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• 2010

The purpose of this paper is to examine the competence and the methods of problem solving in four operations word problems based on the informal knowledges by five-year-old children. The numbers which are contained in problems consist of the numbers bigger than 5 and smaller than 10. The subjects were 21 five-year-old children who didn't learn four operations. The interview with observation was used in this research. Researcher gave the various materials to children and permitted to use them for problem solving. And researcher read the word problems to children and children solved the problems. The results are as follows: five-year-old children have the competence of problem solving in four operations word problems. They used mental computation or counting all materials strategy in addition problem. The methods of problem solving were similar to that of addition in subtraction, multiplication and division, but the rate of success was different. Children performed poor1y in division word problems. According to this research, we know that kindergarten educators should be interested in children's informal knowledges of four operations including shapes, patterns, statistics and probability. For this, it is needed to developed the curriculum and programs for informal mathematical experiences.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.7
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• pp.211-218
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• 1994

Stochastic computation employs random pulse streams to represent numbers. In this paper, we study a new method to implement the number system which uses the ratio of the numbers of ones and zeros in the pulse streams. In this number system. if P is the probability that a pulse is one in a pulse stream then the number X represented by the pulse stream is defined as P/(1-P). We propose circuits to implement the basic operations such as addition multiplication and sigmoid function with this number system and examine the error characteristics of such operations in stochastic computation. We also propose a neuron model and derive a learning algorithm based on backpropagation for the 3-layered feedforward neural networks. We apply this learning algorithm to a digit recognition problem. To analyze the results, we discuss the errors due to the variance of the random pulse streams and the quantization noise of finite length register.

• Journal of the Korean Operations Research and Management Science Society
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• v.32 no.3
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• pp.1-15
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• 2007

In this paper, the return link of interactive GEO satellite network providing multimedia services is considered. First, we classify data by delay characteristics, and analyze the numbers of expected lost packets and expected delay packets for each data class of each terminal. Next we mathematically formulate optimal rate scheduling model to minimize the weighted sum of the numbers of expected lost packets and expected delay packets considering priority of each data class. We also suggest a dynamic rate scheduling scheme based on Lagrangean relaxation technique and subgradient technique to solve the proposed model in a fast time. Extensive experiments show that the proposed scheme provides encouraging results.

• East Asian mathematical journal
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• v.40 no.2
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• pp.267-286
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• 2024

This study investigates the perceptions toward prospective elementary teachers regarding the revised 2015 elementary mathematics curriculum. The aim is to understand the importance and implementation of the revised curriculum and provide implications for curriculum improvement in elementary teacher education institutions, using Interpretative Phenomenological Analysis (IPA). The research findings are as follows: Firstly, prospective elementary teachers perceived that the areas of the revised 2015 elementary mathematics curriculum that require particular focus are number and operations and data and probability. Secondly, they identified the specific elements within these areas that demand dedicated attention as follows: numbers up to four digits in number and operations, mixed calculations with natural numbers, shapes of solid figures, spatial sense of solid figures, comparison of quantities in measurement, etc. These findings can inform the improvement of the curriculum in elementary teacher education institutions.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2876-2878
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• 1999

There have been several tipical methods being used to measure the fuzziness (entropy) of fuzzy sets. Pedrycz is the original motivation of this paper. This paper studies the entropy variation on the fuzzy numbers with arithmetic operations(addition, subtraction, multiplication). It is shown that through the arithmetic operations, the entropy of the resultant fuzzy number has the arithmetic relation with the entropy of each original fuzzy number. This paper generalize earlier results of Pedrycz [FSS 64(1994) 21-30] and Wang and Chiu [FSS 103(1999) 443-455].

• Communications of Mathematical Education
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• v.28 no.3
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• pp.375-394
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• 2014

The purpose of this study is to examine the transition of mathematical representation in Joseon mathematics, which is focused on numbers and operations, letters and expressions. In Joseon mathematics, there had been two numeral systems, one by chinese character and the other by counting rods. These systems were changed into the decimal notation which used Indian-Arabic numerals in the late 19th century passing the stage of positional notation by Chinese character. The transition of the representation of operation and expressions was analogous to that of representation of numbers. In particular, Joseon mathematics represented the polynomials and equations by denoting the coefficients with counting rods. But the representation of European algebra was introduced in late Joseon Dynasty passing the transitional representation which used Chinese character. In conclusion, Joseon mathematics had the indigenous representation of numbers and mathematical symbols on our own. The transitional representation was found before the acceptance of European mathematical representations.

• Journal of the Korean Operations Research and Management Science Society
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• v.13 no.1
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• pp.31-38
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• 1988

This paper presents a methodology for the development of a part classification and coding system suited to each individual company. When coding a group of parts for a specific company by a general purpose part classification & coding system like OPITZ system, it is frequently observed that we use only a small subset of total available code numbers. Such sparsity in the actual occurrences of code numbers implies that we can design a better system which uses digits of the system more parsimoniously. A 2-dimensional fuzzy ISODATA algorithm is developed to extract the important characteristics for the classification from the set of given parts. Based on the extracted characteristics nd the distances between fuzzy clustering cenetroids, a company-unique classification and coding system can be developed. An example case study for a medium sized machine shop is presented.

• Journal of Chest Surgery
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• v.26 no.11
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• pp.874-880
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• 1993

A personal computer, IBM compatible 386, was utilized to analyse total series of 1867 cases of cardiovascular operations including 1060 cases of open cardiac surgeries performed at the Cardiac Center of Paik Hospital from 1986 to 1992.All data were first assembled from the operation files and the operation records from the patient charts. Code numbers were placed to the diagnosis, the operations and the diseases.The analysis revealed the distributions of 1867 cases of operations;819 cases[77%] of the congenital heart diseases and 207 cases[20%] of the acquired heart diseases among 1060 open heart operations. The operative mortalities were 3.7% for the congenital heart diseases and 6.3% for the acquired heart diseases.The vascular operations showed the operative mortalities of 11.8% for the aortic surgery under extracorporeal circulation and 0.7% for the other vascular surgery.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.3
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• pp.277-281
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• 2005

We study some operations of two quadratic fuzzy numbers defined by quadratic curves. And we calculate the normal fuzzy probability for fuzzy numbers generated by the operations.

• East Asian mathematical journal
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• v.26 no.2
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• pp.179-190
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• 2010

We study the theoretical background on the relationship between the equality property and operations treated in different sub-areas in secondary school mathematics curriculum respectively studied. Furthermore, we discuss in detail the equality property in rational numbers field $\mathbb{Q}$ and the real numbers field $\mathbb{R}$. Through this study, professional knowledges of school teachers are enhanced so that these aforementioned knowledges are connected smoothly to teaching activities in classrooms.