• Journal of the Korean Mathematical Society
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• v.40 no.4
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• pp.695-708
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• 2003

We study the existence of solutions for overdetermined PDE systems that admit prolongation to a complete system. We reduce the problem to a Pfaffian system on a submanifold of the jet space of unknown functions and then express the integrability conditions in terms of the coefficients of the original system. As possible applications we present some local problems in CR geometry: determining the CR embeddibility into spheres and the existence of infinitesimal CR automorphisms.

• Journal of the Korean Mathematical Society
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• v.37 no.2
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• pp.193-223
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• 2000

In the late 1970's, M. Kuranishi proposed to control the moduli of the germ of a normal Stein space by deformations of the CR structure on the boundary. I this paper, we will see that it is naturally accomplished by considering stably embeddable deformations of CR structures.

• Journal of the Korean Mathematical Society
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• v.40 no.4
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• pp.667-680
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• 2003

The mirror conjecture means originally the deep relation between complex and symplectic geometry in Calabi-Yau manifolds. Recently, this conjecture is posed beyond Calabi-Yau, and even to, open manifolds (e.g. $A_{n}$ singularities and its resolution) is discussed. While if we treat open manifolds, we can't avoid the boundary (in our case, CR manifolds). Therefore we pose the more precise conjecture (mirror symmetry with boundaries). Namely, in mirror symmetry, for boundaries, what kind of structure should correspond\ulcorner For this problem, the $A_{n}$ case is studied.

• The Pure and Applied Mathematics
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• v.11 no.3
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• pp.175-187
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• 2004

The purpose of the present paper is to study the generalized CR-sub manifold of a T-manifold. After preliminaries we have studied the integrability of the distributions and obtained the conditions for integrability. Then geometry of leaves are being studied. Finally it is proved that every totally umbilical generalized CR-submanifold of a T-manifold is totally geodesic.

• Kyungpook Mathematical Journal
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• v.56 no.3
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• pp.965-977
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• 2016

The aim of this paper is to study the geometry of contact CR-warped product submanifolds in a cosymplectic manifold. We search several fundamental properties of contact CR-warped product submanifolds in a cosymplectic manifold. We also give necessary and sufficient conditions for a submanifold in a cosymplectic manifold to be contact CR-(warped) product submanifold. After then we establish a general inequality between the warping function and the second fundamental for a contact CR-warped product submanifold in a cosymplectic manifold and consider contact CR-warped product submanifold in a cosymplectic manifold which satisfy the equality case of the inequality and some new results are obtained.

• East Asian mathematical journal
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• v.25 no.4
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• pp.495-504
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• 2009

We introduce three classes of quaternion lightlike submanifolds, screen real lightlike submanifolds and CR lightlike submanifolds of an indefinite quaternion Kaehlerian manifold and study the geometry of leaves of their distributions.

• Journal of Korea Multimedia Society
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• v.9 no.8
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• pp.982-999
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• 2006

In this paper, we propose an automatic facial phrenology analysis and avatar drawing system based on internet using multi color information and face geometry. In the proposed system, we detect face using logical product of Cr and I which is a components of YCbCr and YIQ color model, respectively. And then, we extract facial feature using face geometry and analyze user's facial phrenology with the classification of each facial feature. And also, the proposed system can make avatar drawing automatically using extracted and classified facial features. Experimental result shows that proposed algorithm can analyze facial phrenology as well as detect and recognize user's face at real-time.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.57-60
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• 2002

Facial features are often used for human computer interface(HCI). This paper proposes a method to detect facial features using color and facial geometry information. Face region is first extracted by using color information, and then the pupils are detected by applying a separability filter and facial geometry constraints. Mouth is also extracted from Cr(coded red) component. Experimental results shows that the proposed detection method is robust to a wide range of facial variation in position, scale, color and gaze.

• Honam Mathematical Journal
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• v.46 no.1
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• pp.47-59
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• 2024

The purpose of the Nash embedding theorem was to take extrinsic help for studying the intrinsic Riemannian geometry. To realize this aim in actual practice there is a need for optimal relationships between the known intrinsic invariants and the main extrinsic invariants for Riemannian submanifolds. This paper aims to provide an optimal relationship for CR-warped product submanifolds of locally conformal Kähler manifolds.

• Journal of the Korean Mathematical Society
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• v.43 no.5
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• pp.1019-1045
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• 2006

As a natural generalization of a Sasakian space form, we define a contact strongly pseudo-convex CR-space form (of constant pseudo-holomorphic sectional curvature) by using the Tanaka-Webster connection, which is a canonical affine connection on a contact strongly pseudo-convex CR-manifold. In particular, we classify a contact strongly pseudo-convex CR-space form $(M,\;\eta,\;\varphi)$ with the pseudo-parallel structure operator $h(=1/2L\xi\varphi)$, and then we obtain the nice form of their curvature tensors in proving Schurtype theorem, where $L\xi$ denote the Lie derivative in the characteristic direction $\xi$.