• The Pure and Applied Mathematics
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• v.12 no.3 s.29
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• pp.211-221
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• 2005

The purpose of this paper is to study the geometry of null curves in a Lorentzian manifold (M, g). We show that it is possible to construct new type of Frenet equations of null curves in M, supported by two examples.

• The Pure and Applied Mathematics
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• v.16 no.3
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• pp.271-276
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• 2009

We study the geometry of screen conformal light like hypersurfaces M of a semi- Riemannian manifold M. The main result is a characterization theorem for screen conformal lightlike hypersurfaces of a semi-Riemannian space form.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.4
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• pp.665-673
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• 2011

In this paper, we derive a set of the partial differential equations that characterize an inelastic flow of a curve in a 3-dimensional Galilean space. Also, we give necessary and sufficient condition for an inelastic flow.

• Bulletin of the Korean Mathematical Society
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• v.59 no.2
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• pp.351-360
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• 2022

We prove that a punctured-torus group of hyperbolic 4-space which keeps an embedded hyperbolic 2-plane invariant has a strictly parabolic commutator. More generally, this rigidity persists for a punctured-surface group.

• Communications of the Korean Mathematical Society
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• v.38 no.4
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• pp.1249-1260
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• 2023

In the present paper, we study a semi-symmetric recurrent metric connection and verify its various geometric properties.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.4
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• pp.437-457
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• 2019

In this study, we analyzed how the content and achievement criteria of the Geometry domain of Korean elementary school mathematics curriculum have changed. To this end, based on the analysis framework based on the 2015 revised curriculum, the achievement standards for each period were classified into continuous, extinct, and additional types, and their characteristics were examined. In the domain of Geometry, continuous achievement standards accounted for 51% of the total, and there were many achievement standards that remained unchanged in grade and domain. The extinctive achievement standard is 20.4% of the total, and the mathematics contents that were rapidly introduced due to the modernization of mathematics in the 3rd curriculum were eliminated the most from the 4th curriculum, and after the 7th curriculum, With the introduction of staged curriculum and the system of school year group, the contents of learning were either integrated or moved to middle school. The additional achievement standard was 28.6% of the total, and the achievement standard was added the most with the introduction of spatial sensory development in the 7th curriculum. The GAct that the additivel achievement standard is more than the extinction achievement standard in the Geometry domain is the result of the efforts to actively introduce the geometric contents appropriate to the times despite the great flow of curriculum revision of the curriculum reduction. It is hoped that the results of these studies will be used as basic data in the formation of new achievement standards in future curriculum development.

• Journal of Elementary Mathematics Education in Korea
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• v.20 no.2
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• pp.239-257
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• 2016

The Common Core States Standards was developed by building on the best state standards in the U.S.; examining the expectations of other highperforming countries around world; and carefully studying the research and literature available on what students need to know. The Common Core States Standards for Mathematics are reshaping the teaching and learning of mathematics in California classroom using the California Common Core States Standards for Mathematics(CA CCSSM). The aim of this study is to observe CA CCSSM. The CA CCSSM were established to address the problem of having a curriculum that is 'a mile wide and an inch deep'. And it have two types of standards. One is standards for mathematical practice which are the same at each grade level, the other is standards for mathematical content which are different at each grade level. This study focused on standards for mathematical content, in particular, on Geometry domain in elementary level, using Mathematics Framework for California Public Schools.

• Research in Mathematical Education
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• v.15 no.1
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• pp.1-14
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• 2011

Logo has influenced many researchers and learners for the past decades as a 20 turtle geometry environment in the perspective of constructionism. Logo uses the metaphor of 'playing turtle' that is intrinsic, local and procedural. We, then, design an environment in which the metaphor of 'playing turtle' is applied to construct 3D objects, and we figure out ways to represent 3D objects in terms action symbols and 3D building blocks. For this purpose, design three kinds of representation systems, and asked students make various 3D artifacts using various representation systems. We briefly introduce the results of our investigation into students' cognitive burden when they use those representation systems, and discuss the future application measures and the design principles of Logo-based 3D microworld.

• Research in Mathematical Education
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• v.18 no.1
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• pp.41-54
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• 2014

This study investigated the visual-mental capability of pre-service and in-service mathematics teachers as well as academicians making a career change to mathematics teachers with regard to manipulations of two geometric shapes (from 2- to 3-dimensional). Moreover, it investigated whether there are differences between the visual-mental capability of these participant groups. Findings illustrate that most of the participants demonstrate an adequate visual capability relating to the task dealing with a cube. Conversely, very low percentage of participants manifested a visual-mental capability in a task requiring the identification of a solid resulting from rotation of a square page, whose diagonal serves as the rotation axis. The study indicates that learners' high visual view should be developed in order to enhance their visual-mental capability.

• The Mathematical Education
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• v.38 no.2
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• pp.179-187
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• 1999

Math teachers are very short of computer tools and manipulatives to use in geometry classes of middle schools for the development of spatial abilities. At most they can ask student to make regular polyhedrons for helping the students to understand by concrete experience, but this experience is not enough to develop spatial abilities in spatial figures including the regular polyhedrons. This article is to introduce instructional materials for development of spatical ability in the regular polyhedrons using computer software, Geometer's Sketchpad. In this article, students can imagine the whole figure through the parts of a plane figure and think of the parts from the solid figure by free movement from 2 dimensions to 3 dimensions, or from 3 dimensions to 2 dimensions. Also, the instructional materials devised in this article will be good to enhance spatial abilities because the relation of 1-1 correspondence in the movement of the parts can be conserved and observed precisely, which is very hard to demonstrate and visualize by paper-and-pencil. It is recommended that this kind of materials should be developed in various ways for teachers to use them directly in their geometry classes.