• Journal of the Korean School Mathematics Society
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• v.11 no.4
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• pp.609-627
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• 2008

The purpose of this research was to investigate the relationship between the students' strategy types and the recognition for proportional situations. The students' strategy types which were based on the results of ratio and proportion tests were divided into an additive type, a multiplicative type, and a formal type. This research analyzed the students' activities of categorization when were given the proportional problems and nonproportional problems to the students. And it also explored how to develop students' recognizing for the discrimination between the proportional situations and nonproportional situations. The results was the following. First, the students didn't discriminate the proportional situations and the nonproportional situations in the initial state but they came to discriminate little by little. Secondly, the students didn't discriminate the direct proportions and the inverse proportions until the last stage. Third, the multiplicative type was outperformed more than the formal type in solving the ratio and proportion problems but the formal type was outperformed more than the multiplicative type in discriminating between proportional situations and nonproportional situations. These results are interpreted as showing that solving ratio and proportion tasks and recognizing proportional situations are different aspects of proportional reasoning and it is necessary to understand multiplicative strategy with formal strategy in recognizing proportional situations.

• The Mathematical Education
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• v.51 no.2
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• pp.115-129
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• 2012

The values and methods of mathematics education which mathematics teachers tried to impart to their students have varied historically according to the situations of each institution. The cases of the mathematics education in Cambridge University and University College, London show that the peculiar meanings or values of mathematics education were transmitted on students and the methods or focus of the teaching were uniquely determined under the influences of university examinations or conditions of students. In specific, the characteristic education of Augustus De Morgan who studied in Cambridge University and then taught in University College, London reveals better the different institutional contexts. In this paper, I suggest mathematics teachers reconsider mathematics learning motivations on their institutional contexts.

• Research in Mathematical Education
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• v.10 no.3 s.27
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• pp.205-213
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• 2006

In this research, we interviewed primary school teachers and students with hypothetical situations questions and got a comprehensive picture of the status quo of what is happening in the new mathematics classrooms of Mainland China, that is, teachers' conceptions of mathematics and their teaching approaches influence the students' conceptions of mathematics to a large extent. For the teacher who emphasizes the precision and rigidity of mathematics, her students focus on the superficial characteristics of mathematics. On the contrary, for the teacher who believes that mathematics is an open process, related to real life and rich in content, her students are more interested in mathematics and have more diverse conceptions.

• Bulletin of the Korean Mathematical Society
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• v.44 no.1
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• pp.87-94
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• 2007

We in this note introduce the concept of g-IFP rings which is a generalization of IFP rings. We show that from any IFP ring there can be constructed a right g-IFP ring but not IFP. We also study the basic properties of right g-IFP rings, constructing suitable examples to the situations raised naturally in the process.

• Bulletin of the Korean Mathematical Society
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• v.44 no.2
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• pp.215-223
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• 2007

We in this note introduce the concept of NCI rings which is a generalization of NI rings. We study the basic structure of NCI rings, concentrating rings of bounded index of nilpotency and von Neumann regular rings. We also construct suitable examples to the situations raised naturally in the process.

• Journal of applied mathematics & informatics
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• v.13 no.1_2
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• pp.501-508
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• 2003

Although the estimate of regression function is important, some have focused the variance estimation of error term in regression model. Different variance estimators perform well under different conditions. In many practical situations, it is rather hard to assess which conditions are approximately satisfied so as to identify the best variance estimator for the given data. In this article, we suggest SHM estimator compared to LS estimator, which is common estimator using in parametric multiple regression analysis. Moreover, a combined estimator of variance, VEM, is suggested. In the simulation study it is shown that VEM performs well in practice.

• Journal of applied mathematics & informatics
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• v.35 no.3_4
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• pp.331-347
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• 2017

Soft sets are fantastic mathematical tools to handle imprecise and uncertain information in complicated situations. In this paper, we defined the hybrid structure which is the combination of soft set and complex number representation of intuitionistic fuzzy set. We defined basic set theoretic operations such as complement, union, intersection, restricted union, restricted intersection etc. for this hybrid structure. Moreover, we developed this theory to establish some more set theoretic operations like Disjunctive sum, difference, product, conjugate etc.

• Korean Journal of Mathematics
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• v.23 no.1
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• pp.37-46
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• 2015

We in this note introduce the concept of semi-IFP rings which is a generalization of IFP rings. We study the basic structure of semi-IFP rings, and construct suitable examples to the situations raised naturally in the process. We also show that the semi-IFP does not go up to polynomial rings.

• Honam Mathematical Journal
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• v.35 no.2
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• pp.251-302
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• 2013

We study convolution sums of certain restricted divisor functions in detail and present explicit evaluations in terms of usual divisor functions for some specific situations.

• Industrial Engineering and Management Systems
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• v.14 no.2
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• pp.183-195
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• 2015

In this paper, we propose a two-stage group acceptance sampling plan for generalized inverted exponential distribution under truncated life test. Median life is considered as a quality parameter. Design parameters are obtained to ensure that true median life is longer than a given specified life at certain level of consumer's risk and producer's risk. We also explore situations under which design parameters based on median lifetime can be used for other percentile points. Tables and specific examples are reported to explain the proposed plans. Finally a real data set is analyzed to implement the plans in practical situations and some suggestions are given.