• Communications of the Korean Mathematical Society
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• v.38 no.3
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• pp.847-863
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• 2023

We introduce the study of generic lightlike submanifolds of a semi-Riemannian product manifold. We establish a characterization theorem for the induced connection on a generic lightlike submanifold to be a metric connection. We also find some conditions for the integrability of the distributions associated with generic lightlike submanifolds and discuss the geometry of foliations. Then we search for some results enabling a generic lightlike submanifold of a semi-Riemannian product manifold to be a generic lightlike product manifold. Finally, we examine minimal generic lightlike submanifolds of a semi-Riemannian product manifold.

• The Pure and Applied Mathematics
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• v.7 no.2
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• pp.115-127
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• 2000

The purpose of this paper is to prove the fundamental existence and uniqueness theorems of null curves in semi-Riemannian manifolds M of index 2.

• Journal of the Korean Mathematical Society
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• v.31 no.2
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• pp.205-211
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• 1994

• Honam Mathematical Journal
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• v.36 no.4
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• pp.731-737
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• 2014

In this article, we study the transverse Killing forms with finite global norms on complete foliated Riemannian manifolds.

• Korean Journal of Mathematics
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• v.7 no.2
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• pp.235-244
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• 1999

We will derive some identities related to p-scalars, p-vectors, and non-holonomic frames in a generalized 2-dimensional Riemannian manifold $X_2$.

• Journal of the Korean Mathematical Society
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• v.44 no.1
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• pp.109-127
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• 2007

We classify complete, locally homogeneous metrics with finite volume on four-dimensional manifolds which are critical points for the squared $L^2-norm$ functionals of either the full Riemannian curvature tensor or the Weyl curvature tensor defined on the space of Riemannian metrics.

• Journal of the Korean Mathematical Society
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• v.38 no.5
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• pp.955-970
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• 2001

Two compact Riemannian manifolds are said to be isospectral if the associated Laplace-Beltrami operators have the same eigenvalue spectrum. We describe a method, based on the used of Riemannian submersions, for constructing isospectral manifolds with different local geometry and survey examples constructed through this method.

• Honam Mathematical Journal
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• v.35 no.3
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• pp.329-342
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• 2013

We study lightlike hypersurfaces M of a semi-Riemannian space form $\tilde{M}(c)$ with a semi-symmetric non-metric connection whose structure vector field is tangent to M. Our main result is two characterization theorems for such a lightlike hypersurface.

• Bulletin of the Korean Mathematical Society
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• v.39 no.2
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• pp.237-249
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• 2002

We study nondegenerate immersions of Riemannian manifolds of constant sectional curvatures into Lorentzian manifolds of the same constant sectional curvatures with flat normal bundles. We also give a method to produce such immersions using the so-called Grassmannian system. .

• Journal of the Korean Mathematical Society
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• v.39 no.3
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• pp.411-424
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• 2002

We construct the canonical connection associated with a hypercontact structure. Moreover, we discuss the canonical connection associated with a sub-Riemannian 3-structure. As an application, we study the sub-symmetry property in terms of the canonical connection.