• Korean Journal of Child Studies
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• v.36 no.4
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• pp.229-242
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• 2015

The purpose of this study was to investigate young children's nonsymbolic arithmetic ability according to task difficulty. The participants in this study comprised 43 2-year-old children and 48 4-year-old children recruited from 5 childcare centers located in Seoul, Korea. All tasks were composed of comparison, addition, subtraction, multiplication and division tasks. In addition, each arithmetic task varied with the ratio of the two quantities; low level(1:2), middle level(2:3), high level(4:5). The results revealed that 2 & 4-year-old children could perform a large numerical range of nonsymbolic arithmetic tasks without influences from previously learned mathematics. This finding suggests that children have a degree of numerical capacity prior to symbolic mathematics instruction. Furthermore, children's performance on nonsymbolic arithmetic tasks indicated the ratio signature of large approximate numerical representation. This result implies that large approximate numerical representation can be used in arithmetical manipulations.

• The Journal of the Korea Contents Association
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• v.10 no.9
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• pp.97-106
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• 2010

Various time series representation methods have been suggested in order to process time series data efficiently and effectively. SAX is the representative time series representation method combining segmentation and discretization techniques, which has been successfully applied to the time series classification task. But SAX requires a large number of segments in order to represent the meaningful dynamic patterns of time series accurately, since it loss the dynamic property of time series in the course of smoothing the movement of time series. Therefore, this paper suggests a new time series representation method that combines PIPs detection and Persist discretization techniques. The suggested method represents the dynamic movement of high-diemensional time series in a lower dimensional space by detecting PIPs indicating the important inflection points of time series. And it determines the optimal discretizaton ranges by applying self-transition and marginal probabilities distributions to KL divergence measure. It minimizes the information loss in process of the dimensionality reduction. The suggested method enhances the performance of time series classification task by minimizing the information loss in the course of dimensionality reduction.

• Communications of Mathematical Education
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• v.29 no.2
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• pp.215-239
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• 2015

A goal of this study is figuring out how fraction learning centered on various representation activities influences the fraction comprehension and mathematical attitudes. The study focused on 33 4th-grade students of B elementary school in Seoul. In the study, 15 fraction learning classes comprising enactive, iconic, and symbolic representations took place over 6 weeks. After the classes, the ratio of the students who achieved relational understanding increased and the students averagely recorded 90 pt or more on the fraction comprehension test I, II and III. Two-dependent samples t-test was conducted to analyze a significant difference in mathematical attitudes between pre-test and post-test. On the test result, there was the meaningful difference with 0.01 level of significance. To conclude, the fraction learning centered on various representation activities improves students' relational understanding and fraction understanding. In addition, the fraction learning centered on various representation activities gives positive influences on mathematical attitudes since it increases learning orientation, self-control, interests, value cognition, and self-confidence of the students and decreases fears of the students.

• Journal of KIISE:Databases
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• v.32 no.4
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• pp.383-393
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• 2005

Retrieval of images from image databases by spatial relationship can be effectively performed through visual interface systems. In these systems, the representation of image with 2D strings, which are derived from symbolic projections, provides an efficient and natural way to construct image index and is also an ideal representation for the visual query. With this approach, retrieval is reduced to matching two symbolic strings. However, using 2D-string representations, spatial relationships between the objects in the image might not be exactly specified. Ambiguities arise for the retrieval of images of 3D scenes. In order to remove ambiguous description of object spatial relationships, in this paper, images are referred by considering spatial relationships using the spatial location algebra for the 3D image scene. Also, we remove the repetitive spatial relationships using the several reduction rules. A reduction mechanism using these rules can be used in query processing systems that retrieve images by content. This could give better precision and flexibility in image retrieval.

• Journal of the Korean Society of Clothing and Textiles
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• v.31 no.9_10
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• pp.1384-1395
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• 2007

The purpose of this study was to investigate the factors of hairdo attitude and hairdo involvement, the differences in the hairdo involvement by hairdo attitude. The questionnaires were given to female residents in Seoul and Kyung-gi do during September to October 2006. 406 questionnaires were used for data analysis. The collected data were analyzed using SPSS 12.0 software such as factor analysis, Cronbach's alpha, ANOVA test and Duncan test. The results of this study were as follows: 1. The hairdo attitude factors were found to be 'leader's fashion conformity', 'distinct individuality', 'constancy', and 'consciousness of others' The hairdo involvement factors were found to be 'interests in hairdo', 'fashionableness', 'symbolic representation', 'risk awareness', and 'coordination of hairdo'. 2. As for the hairdo attitude, two groups were identified as the highly-oriented group and the lowly-oriented group. There were significant differences in all hairdo involvement factors depending on two groups. Highly-oriented groups of 'leader's fashion conformity' considered more about interests in hairdo, fashionableness, symbolic representation, and coordination of hairdo, except for risk awareness, signalling that the more people respond to leader's fashion, the higher they are involved with hairdo. Highly-oriented group of 'constancy' showed significant differences in fashionableness and risk awareness. Lower level of fashionableness but higher level of risk awareness than the lowly-oriented group. Highly-oriented group of 'consciousness of others' displayed high performance in all factors, implying that the more people respond to feedback and evaluation of others, the higher they are involved with hairdo.