• Journal of Educational Research in Mathematics
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• v.27 no.2
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• pp.191-205
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• 2017

The purpose of this study is to investigate the types and characteristics of the Seventh Graders' proofs. Harel, & Sowder's proof schemes were used to analyze the subjects' responses. As a result of the study, there was a difference in the type of proof schemes used by the students depending on the academic achievement level. While the proportion of students using a transformative proof scheme decreased from the top to the bottom, the proportion of students using inductive (measure) proof scheme increased. In addition, features of each type of proof schemes were shown, such as using informal codes in the proof process, and dividing a given picture into a specific ratio in the problem. Based on this, we extracted four meaningful conclusions and discussed implications for proof teaching and learning.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.910-922
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• 2013

In 2008, Chin et al. proposed an efficient and provable secure identity-based identification scheme in the standard model. However, we discovered a subtle flaw in the security proof which renders the proof of security useless. While no weakness has been found in the scheme itself, a scheme that is desired would be one with an accompanying proof of security. In this paper, we provide a fix to the scheme to overcome the problem without affecting the efficiency as well as a new proof of security. In particular, we show that only one extra pre-computable pairing operation should be added into the commitment phase of the identification protocol to fix the proof of security under the same hard problems.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.495-500
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• 2002

The purpose of this study is to develop and to apply this permanent cement mortar form as one of those system forms to improve existing form's problems. (1) In the fire proof test with combined specimen, the fire proof covering including form section thickness is satisfied with the fire proof criterion. It is considered that form section thickness has no problem (2) The suitable method of normal pressure steam curing for the form's mass production is 4 hours in 65℃ considering production cost, the silica fume admixture is economic.

• School Mathematics
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• v.15 no.3
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• pp.651-665
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• 2013

The aim of this study is to find how unformal proof activities contribute to solving problems successfully and to confirm the role of teachers in the progress. For this, we developed a task that can help students communicate actively with the concept of unformal proof activities and conducted a case lesson with 6 graders in Elementary school. The study shows that unformal proof activities contribute to constructing representations which are needed to solve math problems, setting up plans for problem-solving and finding right answers accordingly as well as verifying the appropriation of the answers. However, to get more out of it, teachers need to develop a variety of tasks that can stimulate students and also help them talk as actively as they can manage to find right answers. Furthermore, encouraging their guessing and deepening their thought with appropriate remarks and utterances are also very important part of what teachers need to have in order to get more positive effect from these activities.

• Journal of the military operations research society of Korea
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• v.30 no.1
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• pp.30-47
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• 2004

This research considers a Network Diversion Problem (NDP) in the directed graph, which is to identify a minimum cost set of links to cut so that any communication paths from a designated source node to a destination node must include at least one link from a specified set of arcs which is called the diversion arcs. We identify a redundant constraint from an earlier formulation. The problem is known to be NP-hard, however a detailed proof has not been given. We provide the proof of the NP-hardness of this problem. We develop a tabu search algorithm that includes a preprocessing procedure with two steps for removing diversion arcs as well as reducing the problem size. Computational results of the algorithm on instances of general graphs and grid graphs are reported.

• Journal of Educational Research in Mathematics
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• v.21 no.2
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• pp.135-148
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• 2011

Middle school mathematics treats axiom as mere fact verified by experiment or observation and doesn't mention it axiom. But axiom is very important to understand the difference between empirical verification and mathematical proof, intuitive geometry and deductive geometry, proof and nonproof. This study analysed textbooks and surveyed gifted students' conception of axiom. The results showed the problem and limitation of middle school mathematics on the treatment of axiom and proof.

• Journal of the Korean Mathematical Society
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• v.47 no.2
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• pp.331-350
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• 2010

We consider the variational problem consisting of minimizing a polyconvex integrand for maps between manifolds. We offer a simple and direct proof of the existence of a minimizing map. The proof is based on Young measures.

• Bulletin of the Korean Mathematical Society
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• v.35 no.1
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• pp.63-74
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• 1998

Our study is dedicated to the the proof of uniqueness of solution of initially boundary value problem in Elastodynamics of initially stressed bodies with voids. This proof is obtained without recourse either to an energy conservation law or to any boundedness assumptions on the elastic coefficients.

• East Asian mathematical journal
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• v.25 no.3
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• pp.299-320
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• 2009

In mathematics, the education of the geometry proof has been playing an important role in promoting the ability for logical thinking by means of developing the deductive reasoning. However, despite of those importance mentioned above, considering the present condition for the education of the geometry proof in middle schools, it is still found that most of classes are led mainly by teachers, operating the cramming system of eduction, and students in those classes have many difficulties in learning the geometry proof course. Accordingly this thesis suggests the other method that is distinguished from previous proof educations. The thesis of Kai-Lin Yang and Fou-Lai Lin on 'A Model of Reading Comprehension of Geometry Proof (RCGP)', which was published in 2007, have various practical examples based on the model. After composing classes based on those examples and instructing the geometry proof, found out a problem. And then advance a new teaching model that amendment and supplementation However, it is considered to have limitation because subjects were minority and classes were operated by man-to-man method. Hopefully, the method of proof education will be more developed through performing more active researches on this in the nearest future.

• School Mathematics
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• v.5 no.4
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• pp.401-420
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• 2003

We have many problems in the teaching and learning of proof, especially in the demonstrative geometry of middle school mathematics introducing the proof for the first time. Above all, it is the serious problem that many students do not understand the meaning of proof. In this paper we intend to show that teaching the meaning of proof in terms of historic-genetic approach will be a method to improve the way of teaching proof. We investigate the development of proof which goes through three stages such as experimental, intuitional, and scientific stage as well as the development of geometry up to the completion of Euclid's Elements as Bran-ford set out, and analyze the teaching process for the purpose of looking for the way of improving the way of teaching proof through the historic-genetic approach. We conducted lessons about the angle-sum property of triangle in accordance with these three stages to the students of seventh grade. We show that the students will understand the meaning of proof meaningfully and properly through the historic-genetic approach.