• Journal of the Korean School Mathematics Society
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• v.15 no.2
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• pp.299-316
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• 2012

In this paper, we examine high school in order to know their ability for understanding about fundamental functions, such as polynomial, trigonometric, logarithm and exponential functions which have learned from high school. The result of this study shows as follows. More than half students are not able to draw shape of given functions, except polynomial. More students do not fully understand about function properties such as domain, codomain, range, maximum and minimum value.

• Journal of the Korean School Mathematics Society
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• v.12 no.3
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• pp.347-364
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• 2009

In this paper, the researchers investigated the influence of graphing calculator in learning the concept of linear function for the gifted students. Elementary students who were taking a course in enrichment mathematics at Science Education Institute for the Gifted in Mokpo National University were selected for this study. The researchers analyzed students' processes of mathematical inference and conjecture, and students' algebraic description. We found the facts that the visualization using a graphing calculator and CBL is helpful to the gifted students in understanding concepts of liner function, finding the relationship between variables, analyzing and presupposing of graph. But, using graphing calculator can be a factor that disturbs learning of students who have too much of curiosity on graphing calculator.

• School Mathematics
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• v.13 no.2
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• pp.323-343
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• 2011

The study of 2011 education course revision proposal suggests that middle school level function shall be taught with emphasis on its role as tool to understand the situations of actual world, and the concept shall be extended in high school into formularized setting that integrate various fields based on middle school function. In revising education course, the circumstances of other countries are desired to be considered to keep abreast of international standard education courses. In this study, the textbooks of Gesamtschule a general school a school type similar to the education system in Korea among various school forms of Germany were selected to look into the characteristics of function introduction and teaching & learning in Germany, and the textbooks were compared and analyzed with those of Korea. As a result of comparison and analysis on the system and contents with emphasis on function area, German textbooks differed from the 7th revised education course on the introduction of function concept, contents development method and method of instructing on graph etc. Such differences are anticipated to serve as data for reference in the development of revised education courses and textbooks in Korea.

• Journal of Educational Research in Mathematics
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• v.27 no.1
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• pp.1-22
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• 2017

This study investigated three $10^{th}$ grade students' concept of rate of change while they perceived changing values of given functions. We have conducted a teaching experiment consisting of 6 teaching episodes on how the students understood and expressed changing values of functions on certain intervals in accordance with the concept of rate of change. The result showed that the students did use the same word of 'rate of change' in their analysis of functions, but their understanding and expression of the word varied, which turned out to have diverse perceptions with regard to average rate of change. To consider these differences as qualitatively different levels might need further research, but we expect that this research will serve as a foundational study for further research in students' learning 'differential calculus' from the perspective of rate of change.

• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.47-57
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• 2006

This study derives an event-based tank model with a conceptual rainfall-infiltration process, modifying conventional tank models. The model comprises two serial tanks, one parallel tank and an infiltration regulating element. The infiltration process within the element is not represented as a function of only time, but as a function of soil moisture content for three possible cases owing to the relationship between rainfall intensity and infiltration capacity. This study considers the previous soil moisture condition of a watershed by using antecedent precipitation index. Six parameters of the model are identified by using the real coded genetic algorithm. The applicability and validity of the proposed model are assessed for the observed stormwater data from the research basin of the International Hydrological Program, the Pyeongchanggang River basin, Republic of Korea. The results computed streamflows show relatively good agreement with observed ones.

• Journal of Korea Water Resources Association
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• v.35 no.3
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• pp.285-294
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• 2002

Infiltration is one of the important processes of the hydrologic cycle determining the distribution of water and has been studied extensively. Various theories and models proposed for this process are usually applicable only when the rainfall intensity is higher than the infiltration capacity. The study by Diskin and Nazimov (1995, 1996) suggested a conceptual infiltration model that comprises two elements. The model can make an reasonable approach to the infiltration process, instead of representing the infiltration as a function of time. The study presented herein improved the existing conceptual infiltration model by an additional consideration of the initial moisture contents. The analysis results for the variation of the infiltration capacity curries for various initial moisture contents demonstrate that the model is more reasonable for the approach to the infiltration process. In addition, the results for the relationship of stormwater events-ponding time are compared with the literature values of that for a number of soil types. The agreement is rather good, leading to the conclusion that the improved model is vapid for describing the infiltration process.

• Journal of the Korean School Mathematics Society
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• v.12 no.4
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• pp.453-472
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• 2009

This article describes the interview data with two preservice teachers where they dealt with five water-filling problems for the investigation of their covariational thinking. The study's results revealed that two students developed their covariation levels from Direction level to Instantaneous Rate with an aid of the pre-constructed GSP simulations for the problem situations. However, this study also points out that there is a missing important feature for a function notion, 'causality' in the covariation framework and suggests that future research should combine students' conception of causality with their covariational thinking for the investigation of their development of a function concept.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.103-111
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• 2005

In this paper, a new meshfree technique which improves the numerical integration accuracy is introduced. This new method called thc Petrov-Galerkin natural clement method(PG-NEM) by authors is based on the Voronoi diagram and the Delaunay triangulation which is based on the same concept used lot conventional natural clement method called the Bubnov-Galerkin natural element method(BG-NEM). But, unlike the BG-NEM, the test basis function is differently chosen, based on the concept of Petrov-Galerkin, such that its support coincides exactly with a regular integration region in background mesh. Therefore, it is expected that the proposed technique ensures the remarkably improved numerical integration accuracy in comparison with the BG-NEM.

• Communications of Mathematical Education
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• v.32 no.2
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• pp.131-146
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• 2018

Differentiation with integration is an important subject which is widely applied in mathematics, natural science, and engineering. Derivative is an important concept of differentiation. But students don't understand its concept well and concentrate on acquiring only the skill to solve the standardized calculus problem. So they are poor at understanding of the concept of differentiation. In this study, after making a survey of differentiation on college students, we try to analyze errors which appeared in solving differentiation problem and investigate mathematics process of limiting process inherent in the derivative and historical development about derivative. Thus, we try to analyze the understanding of differentiation and present the results about this.

• Journal of Educational Research in Mathematics
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• v.9 no.1
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• pp.167-181
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• 1999

The aim of this study is to investigate the influence of graphic calculator in the teaming of function of the underachieved students in the second grade of middle school. Under this purpose of the study, we devised the instruction-plan which incorporates the using of graphic calculator into the traditional paper-and-pencil teaming environments, and executed the function-instruction with the underachieved students according to the devised instruction-plan. During the lesson hours, we observed and analysed the contributions and the carefulness of using graphic calculator in the learning of function of the underachieved students. Furthermore, we carried out the pre-test and the post-test to examine the effects of using graphic calculator in the learning of function of the underachieved students.