• 호남수학학술지
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• 제40권1호
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• pp.187-198
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• 2018

In this paper, we study the instantaneous geometric properties of motion of rigid bodies in the Lorentzian plane. For this purpose we define Lorentzian form of Bottemas instantaneous invariants. In these regards, we obtain the necessary and sufficient condition of a Lorentzian plane to be at Cardan position with respect to these invariants.

• 대한수학회지
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• 제33권2호
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• pp.455-468
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• 1996

Certain analytic behavior of geometric objects defined on a Riemannian manifold depends on some very crude properties of the manifold. Some of those crude invariants are the volume growth rate, isoperimetric constants, and the likes. However, these crude invariants sometimes exercise surprising control over the analytic behavior.

• 대한수학회보
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• 제53권4호
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• pp.1095-1103
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• 2016

B. Y. Chen introduced a series of curvature invariants, known as Chen invariants, and proved sharp estimates for these intrinsic invariants in terms of the main extrinsic invariant, the squared mean curvature, for submanifolds in Riemannian space forms. Special classes of submanifolds in Sasakian manifolds play an important role in contact geometry. F. Defever, I. Mihai and L. Verstraelen [8] established Chen first inequality for C-totally real submanifolds in Sasakian space forms. Also, the differential geometry of slant submanifolds has shown an increasing development since B. Y. Chen defined slant submanifolds in complex manifolds as a generalization of both holomorphic and totally real submanifolds. The slant submanifolds of an almost contact metric manifolds were defined and studied by A. Lotta, J. L. Cabrerizo et al. A Chen first inequality for slant submanifolds in Sasakian space forms was established by A. Carriazo [4]. In this article, we improve this Chen first inequality for special contact slant submanifolds in Sasakian space forms.

• 대한수학회논문집
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• 제8권4호
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• pp.699-707
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• 1993

• 대한수학교육학회지:수학교육학연구
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• 제24권4호
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• pp.515-536
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• 2014

본 연구에서는 GSP(Geometer's Sketchpad) 환경의 기하 문제 해결 과정에서 중학교 1학년 학생들이 각자의 작도 접근 방식을 통해 어떻게 기하학적 특성을 인식하고, 자신들의 작도에 대한 이유를 정당화하는지 살펴보았다. 다양한 드래깅 활동을 통해 학생들은 종속성 및 1수준 불변성을 파악하면서 자신의 작도 방식을 결정하였는데, 강건한 작도 방식을 택한 경우 기본 점의 경로를 바로 인식하여 1단계 정당화에 이른 반면, 유연한 작도 방식을 택한 경우에는 많은 시행착오를 거쳐 2수준 불변성과 경로를 인식한 뒤 2단계 정당화에 이르렀다.

• 대한수학회보
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• 제52권6호
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• pp.2071-2093
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• 2015

In this paper, we investigate the similarity transformations in the Minkowski n-space. We study the geometric invariants of non-null curves under the similarity transformations. Besides, we extend the fundamental theorem for a non-null curve according to a similarity motion of ${\mathbb{E}}_1^n$. We determine the parametrizations of non-null self-similar curves in ${\mathbb{E}}_1^n$.

• 대한수학회지
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• 제33권4호
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• pp.1101-1114
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• 1996

In Riemannian geometry, it is one of the important things to study the topological or geometric invariants of manifolds since they characterize the topology of manifolds.

• 대한수학회논문집
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• 제18권1호
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• pp.87-94
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• 2003

We use geometric properties of Gromov-Hausdorff-convergence to present a way to construct rough but natural invariants of metric geometry.

• 대한수학회지
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• 제33권1호
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• pp.137-144
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• 1996

One of the fundamental problems in Riemannian geometry is "How the geometric invariants of Riemannian manifolds influenced by the curvature restriction \ulcorner".ner".uot;.

• 대한수학회논문집
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• 제32권1호
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• pp.147-163
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• 2017

We define de Sitter focal surfaces and hyperbolic focal surfaces of hyperbolic space curves. As an application of the theory of unfoldings of function germs, we investigate the singularities of these surfaces. For characterizing the singularities of these surfaces, we discover a new hyperbolic invariants and investigate the geometric meanings.