• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1093-1100
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• 2015

Since the security of RSA cryptosystem depends on the difficulty of factoring integers, it is the most important problem to factor large integers in RSA cryptosystem. The Lenstra elliptic curve factorization method(ECM) is considered a special purpose factoring algorithm as it is still the best algorithm for divisors not greatly exceeding 20 to 25 digits(64 to 83 bits or so). ECM, however, wastes most time to calculate $M{\cdot}P$ mod N and so Montgomery and Koyama both give fast methods for implementing $M{\cdot}P$ mod N. We, in this paper, further analyze Montgomery and Koyama's methods and propose an efficient algorithm which choose the optimal parameters and reduces the number of multiplications of Montgomery and Koyama's methods. Consequently, the run time of our algorithm is reduced by 20% or so than that of Montgomery and Koyama's methods.

• Korean Journal of Community Nutrition
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• v.12 no.3
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• pp.284-298
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• 2007

This study was performed by a comparative analysis of nutritional knowledge, dietary attitudes and nutrient intakes of dietitians and non-dietitians. The subjects of this study were 103 dietitians and 166 non-dietitians working in the Chonnam area. The general characteristics, nutrition knowledge and dietary attitudes of the subjects were surveyed using a self-administered questionnaire, and nutrient intakes were examined using 24-hour recall method. The results were as follows: Dietitian group ($15.17{\pm}3.88$) scored significantly (p<0.0001) higher than non-dietitian group ($13.34{\pm}3.31$) in nutrition knowledge. Dietitian group ($69.58{\pm}10.67$) scored significantly higher on dietary attitudes than the non-dietitian group ($63.97{\pm}11.18$). The correlation between nutritional knowledge scores and dietary attitudes scores were statistically significance on job, age ($20{\sim}39$), education level (below university), marital status and work experience ($2{\sim}5$, above 10). The dietitian group was significantly higher than the non-dietitians in body weight and BMI of anthropometric data. The prevalence of obesity was 5.8% from the dietitian group and 6.6% from the non-dietitian group when judged by BMI and therefore obesity rate was significaltly (p<0.001) different between the two groups. In case of the dietitian group, the average intake of vitamin A, vitamin $B_1$, vitamin $B_6$, niacin, vitamin E, phosphorous, zinc were above the Korean RDA whereas the average intake of vitamin C, calcium, iron, folic acid were below the Korean RDA. The average intake of most nutrients, except vitamin $B_1$, vitamin $B_6$, phosphorus, were below the Korean RDA in the non-dietitian group. Therefore the non-dietitian group needs nutrition education in order to improve their nutritional status.

• Research in Mathematical Education
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• v.22 no.4
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• pp.261-282
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• 2019

The research related to testing pupils' achievement in the field of Measurement and Measure in initial teaching of geometry points to an insufficient adoption of the basic components of the length measurement concept among pupils. In order to discover the cause, we looked at the basic components on which the procedure of measuring length using a ruler is based, highlighted the possibilities of introducing the procedure in measuring length, and determined pupils' achievement during the procedure of measuring length using a ruler. The research sample consisted of 145 pupils, out of which 72 were the 2^nd grade pupils and 73 were the 4^th grade pupils. A descriptive method was applied in the research. The technique we used was testing, and for the statistical data processing we used a χ² test. The results of the research show that, when drawing a straight line of a given length using a ruler, there is no statistical difference in achievement between the 2^nd and 4^th grade pupils, nor in the pupils' knowledge regarding drawing a ruler independently, while drawing a straight line of a given length using a "broken" ruler 4^th grade pupils are statistically better. The results of the research indicate that pupils' achievement is better in doing standard tasks than in non-standard ones, given that the latter require conceptual knowledge. The components of the concept of length measurement using ruler have not been sufficiently developed yet, and these include: zero-point, partitioning a measured object in a series of consecutive measurement units and their iteration. We shed more light on the critical stage in the procedure of length measurement - the transition from non-standard to standard units and the formation of the length measurement scale. For further research, we propose to look at the formation of the concept of length measurement using the ruler through all its components and their inclusion in the mathematics curriculum, as well as examining the correlation of pupils' achievement in the procedure of measuring length with their achievement in measuring area (and volume).

• Education of Primary School Mathematics
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• v.19 no.1
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• pp.31-45
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• 2016

In this study, the case of error became the object of learning, and the investigator applied these cases to an actual class and established three study problems in order to achieve the purpose of this study. The results of analysis of students' errors in figure based on before achievement test are shown as follows: First, the most errors occurred in the figure was the ones from deficient mastery of prerequisite concepts and definitions. Specially, the errors from deficient mastery of prerequisite concepts and definitions have the majority. it is very high ratio even if it considers an influence of an evaluation question item. so, I think it is necessary to teach concept related figure above all. Second, as the results of application 'finding errors' to a class, there is a meaningful difference in the mathematical achievement and reasoning ability within significance level 5%. This means 'finding errors' is one of the teaching method that it develops the mathematical achievement and reasoning ability.

• Journal of Gifted/Talented Education
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• v.22 no.1
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• pp.23-37
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• 2012

The purpose of this study is to design a more satisfactory and efficient teaching strategy for the gifted by comparing teaching type and learning environment preferred by the gifted with that preferred by normal students. As a result, the following findings are obtained. First, while the normal class students show higher preference for clarification and organization, gifted students prefer for diversification and specialization. Second, with the respect to the gender-related forms of mathematics classroom environment, the overall female preference and the average score are higher, indicating significant difference in the area is only a psychological domain. Third, compared to the regular classroom, the gifted have significantly different preference for teaching method, classroom and teachers' attitude between in the gifted class and regular class.

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.2
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• pp.205-230
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• 2015

The purpose of this study is, targeting 5th and 6th grades mathematically gifted elementary students, to analyze the effect of independent study project learning on self-directed learning ability and mathematical self-efficacy, and based on the results, examine the implications that independent study project learning has in special education for the gifted. In order to solve the study problems, 5th grade mathematically gifted elementary students(40) and 6th grade mathematically gifted elementary students(39) who had passed the selection criteria of D education institute for the gifted and had been receiving special education for the gifted were selected. The study results are as below. First, although self-directed learning ability had no significant difference at p<0.05, it statistically had some differences in averages between pre-test and post-test results. Second, although mathematical self-efficacy had no significant difference at p<0.05, it statistically had some differences in averages between pre-test and post-test results. Third, in the aspects of self-directed learning ability and mathematical self-efficacy, independent study project learning had a more positive effect on 5th grade mathematically gifted elementary students than 6th grade mathematically gifted elementary students. In addition, it had significant differences in 'the level of mathematical tasks', a sub-level of mathematical self-efficacy, and 'the openness of learning', 'the initiative of learning', and 'a sense of responsibility for learning', sub-levels of self-directed learning ability. These results imply that independent study project learning has a positive effect on self-directed learning ability and mathematical self-efficacy of mathematically gifted elementary students so that it could be meaningfully used as a teaching method for special education for the gifted at educational sites of independent study project learning.

• School Mathematics
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• v.11 no.1
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• pp.17-37
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• 2009

Concept and model of multiplication is not single. Concepts of multiplication can be classified into three cases: repeated addition, times idea, pairs set. Models of multiplication can be classified into four cases: measurement, rectangular pattern, combinatorial problem, number line. Among diverse cases of multiplication's concept and model, which case does elementary mathematics education lay stress on? This question is a controvertible didactical point. In this thesis, (1) mathematical and didactical analysis of multiplication's concept and model is performed, (2) a concrete program of teaching multiplication which is based on times idea is contrived, (3) With this new program, the teaching experiment is performed and its result is analyzed. Through this study, I obtained the following results and suggestions. First, the degree of testee's understanding of times idea is not high. Secondly, a sort of test problem which asks the testee to find times value is more easy than the one to find multiplicative resulting value. Thirdly, combinatorial problem can be handled as an application of multiplication. Fourthly, the degree of testee's understanding of repeated addition is high. In conclusion, I observe the fact that this new program which is based on times idea could be a alternative program of teaching multiplication which could complement the traditional method.

• Journal of Educational Research in Mathematics
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• v.22 no.2
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• pp.203-227
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• 2012

This was to investigate how the slow learners who specially belonged to low-SES, or North Korean defectors showed their errors in mathematical learning. To conduct the study, two groups for each minority group participated in the study volunteerly during the Winter vacation, in 2011. Based on the preliminary interviews, a total of 15 units were given, focusing on building mathematical basic concepts. As results, they had some errors in common. They both were in lack of understanding of the terminologies and not able to apply the meanings of definitions and theorems to a problem. Because of uncertainty of basic knowledge of mathematics, they easily lost their focus and were apt to make a mistake. Also, they showed clear differences. North Korean defectors were not accustomed to using or understanding the meanings of Chines or English in Korean words in expressing, writing mathematical terminologies and reading data on the context. Technical errors, and misinterpreted errors were found. However, students from the low SES showed that they were familiar with mathematical words and terminologies, but their errors mostly belonged to carelessness because of the lack of mastering mathematical concepts.

• School Mathematics
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• v.18 no.3
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• pp.625-645
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• 2016

This study clarified the big ideas related to teaching addition and subtraction of fractions with different denominators based on quantitative reasoning with unit and recursive partitioning. An analysis of this study urged us to re-consider the content related to the addition and subtraction of fraction. As such, this study analyzed textbooks and teachers' manuals developed from the fourth national mathematics curriculum to the most recent 2009 curriculum. In addition and subtraction of fractions with different denominators, it must be emphasized the followings: three-levels unit structure, fixed whole unit, necessity of common measure and recursive partitioning. An analysis of this study showed that textbooks and teachers' manuals dealt with the fact of maintaining a fixed whole unit only as being implicit. The textbooks described the reason why we need to create a common denominator in connection with the addition of similar fractions. The textbooks displayed a common denominator numerically rather than using a recursive partitioning method. Given this, it is difficult for students to connect the models and algorithms. Building on these results, this study is expected to suggest specific implications which may be taken into account in developing new instructional materials in process.

• Communications of Mathematical Education
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• v.28 no.1
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• pp.1-17
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• 2014

Recently a student's mathematical thinking and problem-solving skills are emphasized. Nevertheless, the students solved the problem associated with a given type of problem solving using mechanical algorithms. With this algorithm, It's hard to achieve the goal that are recently emphasized. Furthermore It may be formed error or misconception. However, consistent errors have positive aspects to identify of the current cognitive state of the learner and to provide information about the cause of the error. Thus, this study tried to analyze the error happening in the process of solving gearwheel-involved problem and to propose the correct teaching method. The result of student's error analysis, the student tends to solve the gear-wheel problem with proportional expression only. And the student did not check for the proportional expression whether they are right or wrong. This may be occurred by textbook and curriculum which suggests only best possible conditioned problems. This paper close with implications on the discussion and revision of the concepts presented in the curriculum and sequence related to the gearwheel-involved problem as well as methodological suggested of textbook.