• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1351-1362
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• 1992

Qualitative models in model-based expert system needs modeling paradigm which provides intelligent control of modeling assumptions and extracts robust inferences without quantitative information about the system to be modeled. Qualitative reasoning methodologies has proved the property of the completeness but not the soundness to the corresponding quantitative model. We propose new methodology of qualitative reasoning by introducing the concept of Centroid-Oriented Composite Interval to improve the soundness problem. Arithmetic operations and equivalence classes were composed using this definition. Qualitative simulation results were compared to Kuipers's results and the improvements in the soundness problem is verified.

• Journal of Elementary Mathematics Education in Korea
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• v.19 no.3
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• pp.387-408
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• 2015

The purpose of this research is to analyze the mathematical tasks of length measurement in two different perspectives, the level of cognitive demands and learning trajectories, and restructure the mathematical tasks so that the students' conceptual learning is promoted and students are able to have opportunities to think more broadly. Ten lessons with the restructured mathematical tasks were implemented for a class of 2nd grade elementary students. Also a qualitative and in-depth study was conducted with 4 students of the target group. The study shows that firstly, the restructured tasks requiring high level of cognitive skills, had positive effects in increasing the students' level of thinking and reasoning. Secondly, the tasks modified according to the learning trajectories of Szilag, Clements & Sarama(2013) in length measurement, have proven to promote students' concept learning and elaborate the students' level of thinking.

• Journal of Intelligence and Information Systems
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• v.10 no.2
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• pp.91-109
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• 2004

This study investigates the effectiveness of a hybrid approach using fuzzy sets that describe approximate phenomena of the real world. Compared to the other existing techniques, the approach handles inexact knowledge in common linguistic terms as human reasoning does it. Integration of fuzzy sets with case-based reasoning (CBR) is important in that it helps to develop a successful system far dealing with vague and incomplete knowledge which statistically uses membership value of fuzzy sets in CBR. The preliminary results show that the accuracy of the integrated fuzzy-CBR approach proposed for this study is higher that of conventional techniques. Our proposed approach is applied to corporate bond rating of Korean companies.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.531-534
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• 1999

벡터제어기법은 유도전동기의 무부하 시험 및 구속시험 등을 통하여 구한 고정자 및 회전자 상수를 이용한 전동기의 수학적 모델을 기초로 하여 이루어진다. 따라서 유도전동기의 수학적 모델을 구성하는 고정자 및 회전자 상수의 정확성은 곧 벡터제어의 성능과도 직결된다. 하지만, 온도 상승 등의 영향으로 회전자 저항값은 정상치보다 최대 80∼100%까지 상승 할 수 있으며, 이는 벡터제어의 특성을 저하시키는 요인이 된다. 따라서, 본 연구에서는 회전자 저항을 이용하는 자속 PI제어부를 회전자 저항을 사용하지 않는 자속 퍼지제어부로 대체하고 측정한 3상 전류를 이용하여 회전자 저항값의 변화를 실시간으로 추정·보상하는 퍼지추론기를 구성하므로써 회전자 저항의 변화에도 최적의 효율 및 성능을 가지는 보완된 벡터 제어 기법을 개발하였다.

• Communications of Mathematical Education
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• v.23 no.3
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• pp.507-522
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• 2009

In general, we do fold paper and unfold, it remain paper traces. We can be obtained by using rectangular paper, a mathematical fact and the program had a combination. Depending on the direction of the rectangle, folding paper in the form of variety shows valley and ridge signs of the appearance of this paper. By using (0,1)-code and (0,1)-matrix, we study four kinds of research. Therefore, traces of this view upside down rectangle folding paper how to fold inductive reasoning ability of the code and explore the relationship of traces. Finally, the mathematical content and program development can practice in the field.

• Journal of The Korean Association For Science Education
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• v.34 no.4
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• pp.335-347
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• 2014

Size/scale is a central idea in the science curriculum, providing explanations for various phenomena. However, few studies have been conducted to explore student understanding of this concept and to suggest instructional approaches in scientific contexts. In contrast, there have been more studies in mathematics, regarding the use of number lines to relate the nature of numbers to operation and representation of magnitude. In order to better understand variations in student conceptions of size/scale in scientific contexts and explain learning difficulties including alternative conceptions, this study suggests an approach that links mathematics with the analysis of student conceptions of size/scale, i.e. the analysis of mathematical structure and reasoning for a number line. In addition, data ranging from high school to college students facilitate the interpretation of conceptual complexity in terms of mathematical development of a number line. In this sense, findings from this study better explain the following by mathematical reasoning: (1) varied student conceptions, (2) key aspects of each conception, and (3) potential cognitive dimensions interpreting the size/scale concepts. Results of this study help us to understand the troublesomeness of learning size/scale and provide a direction for developing curriculum and instruction for better understanding.

• Communications of Mathematical Education
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• v.26 no.2
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• pp.205-220
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• 2012

In this article convergent sequences with natural number terms are investigated and the behaviors of tails and limits of these natural number sequences are explored. Firstly this study showed how the pre-service teachers response to the intuitive limit definition using "getting closer" for constant sequences. As a case of convergent natural sequences, the sequences in which the latter term is determined by the sum of digit squares of the former term are considered. To exploring these sequences the computational and charting capabilities of spreadsheets are utilized and some mathematical findings are obtained. Spreadsheet can be instrumentalized by teachers or students to provide a laboratory-like environment to explore a mathematical problem.

• Education of Primary School Mathematics
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• v.12 no.2
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• pp.117-132
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• 2009

The purpose of this study was analysis on types of strategies and errors when the sixth grade students were solving proportion problems of mathematics textbooks. For this study, proportion problems in mathematics textbooks were investigated and 17 representative problems were chosen. The 277 students of two elementary schools solved the problems. The types of strategies and errors in solving proportion problems were analyzed. The result of this study were as follows; The percentage of correct answers is high if the problems could be solved by proportional expression and the expression is in constant rate. But the percentage of correct answers is low, if the problems were expressed with non-constant rate.

• Journal of the Korean School Mathematics Society
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• v.16 no.3
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• pp.539-560
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• 2013

The purpose of this study was to investigate characteristics of mathematically gifted high school students' thinking in design activities using GrafEq. Eight mathematically gifted high school students, who already learned graphs of functions and inequalities necessary for design activities, were selected to work in pairs in our experiment. Results indicate that logical thinking and mathematical abstraction, intuitive and structural insights, flexible thinking, divergent thinking and originality, generalization and inductive reasoning emerged in the design activities. Nonetheless, fine-grained analysis of their mathematical activities also implies that teachers for gifted students need to emphasize both geometric and algebraic aspects of mathematical subjects, especially, algebraic expressions, and the tasks for the students are to be rich enough to provide a variety of ways to simplify the expressions.

• Journal of Elementary Mathematics Education in Korea
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• v.6 no.1
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• pp.23-40
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• 2002

Historically, the use of algorithms has been emphasized in the mathematics curriculum at the elementary school mathematics. The current reform movement in our country are seemed to emphasize the importance of algorithms in favor of problem-solving approaches, the conceptualization of mathematical processes and applications of mathematics in real world situations. Recently, children may come to school with a fairly well-developed attitude about mathematics and mathematical ideas. That is, they do not come to school and to learning mathematics with a clean slate. Because they have already formed some partial mathematical concepts in a wide variety of contexts. Many kindergarten children have attended pre-school programs where they played with blocks, made patterns, and started adding and subtracting. It seems that there are psychological change attitudes of the children in upper grades toward learning mathematics. In our elementary school mathematics, almost every student are still math anxious or have developed math anxiety because of paper-pencil test. In these views, this paper is devoted to introduce and apply to second grade students in ND-elementary school in Taegu City the new method for learning addition and subtraction so called ‘Mrs Weill's Hill’, which is believed as a suitable method for children with mathematical teaming disabilities and Math anxiety.