• 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. .

• Bulletin of the Korean Mathematical Society
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• v.35 no.2
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• pp.301-309
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• 1998

The purpose of this paper is to give a theorem of Liouvilletype for complete Riemannian manifolds as an extension of the Theorem of Nishikawa [6].

• Bulletin of the Korean Mathematical Society
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• v.46 no.3
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• pp.577-589
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• 2009

In this paper, we give a classification of contact 3-manifolds whose Ricci tensors are $\eta$-parallel.

• Communications of the Korean Mathematical Society
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• v.28 no.2
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• pp.353-360
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• 2013

We study lightlike hypersurfaces of indefinite Kenmotsu manifolds. The purpose of this paper is to prove that there do not exist totally geodesic screen distributions on semi-symmetric lightlike hypersurfaces of indefinite Kenmotsu manifolds with flat transversal connection.

• Honam Mathematical Journal
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• v.29 no.4
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• pp.641-647
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• 2007

In this paper, we consider the problem of achieving constant scalar curvature on warped product manifolds according to fiber manifolds with constant scalar curvature.

• Honam Mathematical Journal
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• v.29 no.4
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• pp.681-694
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• 2007

We study curvature properties of four-dimensional almost Hermitian manifolds with vanishing Bochner curvature tensor as defined by Tricerri and Vanhecke. We give some structure theorems for such manifolds.

• Honam Mathematical Journal
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• v.41 no.4
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• pp.769-780
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• 2019

We introduce anti-invariant Riemannian submersions from almost paracontact Riemannian manifolds onto Riemannian manifolds. We give an example, investigate the geometry of foliations which are arisen from the definition of a Riemannian submersion and check the harmonicity of such submersions.

• Communications of the Korean Mathematical Society
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• v.19 no.2
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• pp.337-343
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• 2004

Fibrators are closed manifolds which afford instant recognition of approximate fibrations. In this note we determine which 4-manifolds with geometric structure are fibrators.

• Kyungpook Mathematical Journal
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• v.60 no.3
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• pp.535-549
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• 2020

In this paper, we introduce the geometry of contact CR submanifolds and radical transversal lightlike submanifolds of Sasaki-like almost contact manifolds with B-metric. We obtain some new results that establish a relationship between these two submanifolds.

• Bulletin of the Korean Mathematical Society
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• v.37 no.1
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• pp.85-90
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• 2000

On Riemannian manifolds of dimension 4 the Einstein condition is equivalent to the Thorpe condition. In this paper, we construct a few metrics which we Einstein but not Thorpe, and vice versa in dimensions larger than 4.