• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.17 no.2
• /
• pp.177-187
• /
• 1999

Up to date, in many application fields of GSIS, we usually have used vector-based spatial overlay or grid-based spatial algebra for extraction and analysis of spatial data. But, because these methods are based on traditional crisp set, concept which is used these methods. shows that many kinds of spatial data are partitioned with sharp boundary. That is not agree with spatial distribution pattern of data in the real world. Therefore, it has a error that a region or object is restricted within only one attribution (One-Entity-one-value). In this study, for improving previous methods that deal with spatial data based on crisp set, we are suggested to apply into spatial overlay process the concept of fuzzy set which is good for expressing the boundary vagueness or ambiguity of spatial data. two methods be given. First method is a fuzzy interval partition by fuzzy subsets in case of spatially continuous data, and second method is fuzzy boundary set applied on categorical data. with a case study to get a land suitability map for the development site selection of new town, we compared results between Boolean analysis method and fuzzy spatial overlay method. And as a result, we could find out that suitability map using fuzzy spatial overlay method provide more reasonable information about development site of new town, and is more adequate type in the aspect of presentation.

• Journal of the Korean association of regional geographers
• /
• v.13 no.2
• /
• pp.143-155
• /
• 2007

There are many conflicts or interests among various stakeholders on the development of the coastal area. The integrated methodology, which is reflective of physical conditions, socio-economic circumstances, and people's sense of values, is thus needed to solve the problems. In this study, geographical information systems(GIS) and analytic hierarchy process(AHP) that arc one of multi-criteria analysis methodologies are loosely coupled to develop better analytic procedures for coastal assessment. Socio-economic and environmental parameters of the study area, Hampyung Bay area, are converted to a GIS system-applicable format, while AHP is used to assess the relative importance level of each parameter by calculating weighting factors. After standardizing and rasterizing spatial data from various sources. the weighting factors are applied to produce the layers for each parameter. Map algebra and overlay analyses are used to create the final layer according to the decision making logic or model proposed here. Cell values of that layer could be considered as spatial alternatives. In addition to this finding, the flexibility with the weighing factors enable decision-makers to understand the procedures and alternatives in relevance with selective strategies for coastal management.

• Journal of KIISE:Computing Practices and Letters
• /
• v.5 no.5
• /
• pp.543-552
• /
• 1999

The iterator technique which is used for implementing physical operators of the query executor is known for its efficiency and extensibility. The most widely used technique for processing an operator on spatial objects is to process by dividing it into the filter step and the refinement step. Recently, there was a research for an optimizer which can generate more efficient query execution plans than those of traditional methods by separating a spatial operator into filter and refinement steps in the level of the object algebra. But, traditional query executors were not designed considering such query execution plans. So they have no function of transmitting the result of the filter operation between operators. We propose two methods, the probe technique and the tag technique, which transmit the result of the filter operator when using the iterator in the query execution plan in which operators are separated by filter/refinement steps and other operators can be allowed between the steps. Whereas the probe technique extends the state record within an operator, the tag technique stores the result of a filter step in an intermediate result in the form of the tag. Based on the comparison of these methods, we design and implement a query executor using the tag technique that is superior in extensibility. The implemented query executor can execute operations defined in the Spatial Object Algebra(SOA) to process an extended OQL for spatial queries.

• Research in Mathematical Education
• /
• v.18 no.4
• /
• pp.237-256
• /
• 2014

This paper reports findings from a written assessment which was designed to investigate Chinese primary school students' understanding of the equal sign and equation structure. The investigation included a sample of 110 Grade 3, 112 Grade 4, and 110 Grade 5 students from four schools in China. Significant differences were identified among the three grades and no gender differences were found. The majority of Grades 3 and 4 students were found to view the equal sign as a place indicator meaning "write the answer here" or "do something like computation", that is, holding an operational view of the equal sign. A part of Grade 5 students were found to be able to interpret the equal sign as meaning "the same as", that is, holding a relational view of the equal sign. In addition, even though it was difficult for Grade 3 students to recognize the underlying structure in arithmetic equation, quite a number of Grades 4 and 5 students were able to recognize the underlying structure on some tasks. Findings in this study suggest that Chinese primary school students demonstrate a relational understanding of the equal sign and a strong structural sense of equations in an earlier grade. Moreover, what found in the study support the argument that students' understanding of the equal sign is influenced by the context in which the equal sign is presented.

• Korean Journal of Child Studies
• /
• v.34 no.1
• /
• pp.123-140
• /
• 2013

The purpose of this study was to examine the effects of counting ability on young children's mathematical ability and mathematical learning potential. The subjects in this study were 75 young children of 4 & 5 years old who attended kindergartens and child care center in the city of B. They were evaluated in terms of counting ability, mathematical ability and mathematical learning potential(training and transfer) and the correlation between sub-factors and their relative influence on the partipants' mathematical ability was then analyzed. The findings of the study were as follows : First, there was a close correlation between the sub-factors of counting and those of mathematical ability. As a result of checking the relative influence of the sub-factors of counting on mathematical ability, reverse counting was revealed to have the largest impact on total mathematical ability scores and each sub-factors including algebra, number and calculation, geometry and measurement. Second, the results revealed a strong correlation between counting ability and mathematical learning ability. Regarding the size of the relative influence of the sub-factors of counting ability on training scores, reverse counting was found to be most influential, followed by continuous counting. While in relation to transfer scores, reverse counting was found to exert the greatest influence.

• Communications of the Korean Mathematical Society
• /
• v.32 no.1
• /
• pp.7-17
• /
• 2017

Let R be a commutative ring with zero-divisors Z(R). The extended zero-divisor graph of R, denoted by $\bar{\Gamma}(R)$, is the (simple) graph with vertices $Z(R)^*=Z(R){\backslash}\{0\}$, the set of nonzero zero-divisors of R, where two distinct nonzero zero-divisors x and y are adjacent whenever there exist two non-negative integers n and m such that $x^ny^m=0$ with $x^n{\neq}0$ and $y^m{\neq}0$. In this paper, we consider the extended zero-divisor graphs of idealizations $R{\ltimes}M$ (where M is an R-module). At first, we distinguish when $\bar{\Gamma}(R{\ltimes}M)$ and the classical zero-divisor graph ${\Gamma}(R{\ltimes}M)$ coincide. Various examples in this context are given. Among other things, the diameter and the girth of $\bar{\Gamma}(R{\ltimes}M)$ are also studied.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.3
• /
• pp.316-322
• /
• 2009

This paper presents an analytical design method of a passive harmonic filter for a three-phase diode rectifier and uses a new transfer function approach in the analysis and design. The transfer function approach derives an analytical formulation of an utility system including passive filters with a basis of Laplace transform and provides a graphical formulation so that a visualized insight into an interaction between individual filter and system response can be attainted. Harmonic impedance, voltage division and current division transfer function are used as a design tool, which makes a calculated filter parameters to satisfy IEEE-519 distortion limits. A simple five-step design procedure is introduced in the filter design, which consists of system analysis, selection of PCC(Point of Common Coupling), filter specification calculation, appropriate filter design for system and filter implementation. Philosophy governing the design procedure is based on a numerical/graphical iterative solution, trial and error with visualization feed-back based on "algebra on the graph". Finally, performance of the designed passive harmonic filter is verified by experiment and shows that 5th, 7th, 9th, 11th and 13th harmonics are decreased within IEEE-519 distortion limits, respectively.

• Journal of Educational Research in Mathematics
• /
• v.15 no.2
• /
• pp.215-232
• /
• 2005

Computer algebra system (CAS) calculators are becoming increasingly common in schools and universities. While Hey offer quite sophisticated mathematical capability to teachers and students, it is not clear at present how they may best be employed. In particular their integration into students' learning and problem-solving remains an issue. In this paper we address this issue through the lens of a study that considered the introduction of the TI-89 CAS calculator to students about to enter university. We describe a number of different aspects of the partnership they formed with the calculator as they began the process of instrumentation of the CAS in their learning.

• School Mathematics
• /
• v.1 no.1
• /
• pp.135-156
• /
• 1999

The purpose of this study is to discuss about the role of the visualization as an effective method of teaching abstracted mathematics, to analyze visual materials in middle and high school mathematics and to suggest various visualized materials for teaching mathematics effectively. Though formal, symbolic and analytical teaching method is a major characteristic of mathematics, the students should be taught to understand through intuition and insight, and formalize the mathematical concepts progressively. Especially the sight is one of the most important basics of cognition for intuition and insight. Therefore, suggesting mathematical contents through the visual method makes the students understand and formalize the mathematical concepts more easily. In this study, we tried to investigate the meaning and role of visualization in mathematics teaching. And, we discussed about the four roles of visualization in the process of mathematics teaching and learning confirmation and memorization of the mathematical truth, proving theorem and solving problems which is one of the most important purposes of teaching mathematics, According to the roles of visualization, we analyzed visual materials currently taught in middle and high school, and suggested various visual materials useful in teaching mathematics. The investigated fields are algebra where visual materials are little used, and geometry where they are use the most. The paper-made-textbook can't show moving animation vigorously. Hence we suggested visual materials made by GSP and applets in IES .

• Journal for History of Mathematics
• /
• v.23 no.1
• /
• pp.41-52
• /
• 2010

Ancient Indian mathematical works, all composed in Sanskrit, usually consisted of a section of sturas in which a set of rules or problems were stated with great economy in verse in order to aid memorization by a student. And rules or problems of the mathematics were transmitted both orally and in manuscript form.Indian mathematicians made early contributions to the study of the decimal number system, arithmetic, equations, algebra, geometry and trigonometry. And many Indian mathematicians were appearing one after another in Ancient. This paper is a comparative study of mathematics developments in ancient India and the other ancient civilizations. We have found that the Indian mathematics is quantitative, computational and algorithmic by the principles, but the ancient Greece is axiomatic and deductive mathematics in character. Ancient India and the other ancient civilizations mathematics should be unified to give impetus to further development of mathematics education in future times.