• Communications of the Korean Mathematical Society
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• v.27 no.4
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• pp.781-793
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• 2012

We study some properties of a semi-Riemannian submanifold of a semi-Riemannian manifold with a semi-symmetric non-metric connection. Then, we prove that the Ricci tensor of a semi-Riemannian submanifold of a semi-Riemannian space form admitting a semi-symmetric non-metric connection is symmetric but is not parallel. Last, we give the conditions under which a totally umbilical semi-Riemannian submanifold with a semi-symmetric non-metric connection is projectively flat.

• Communications of the Korean Mathematical Society
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• v.30 no.1
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• pp.35-43
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• 2015

We study two types of 1-lightlike submanifolds, so-called lightlike hypersurface and half lightlike submanifold, of an indefinite trans-Sasakian manifold $\bar{M}$ admitting non-metric ${\theta}$-connection. We prove that there exist no such two types of 1-lightlike submanifolds of an indefinite trans-Sasakian manifold $\bar{M}$ admitting non-metric ${\theta}$-connections.

• Bulletin of the Korean Mathematical Society
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• v.44 no.1
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• pp.95-102
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• 2007

We define the non-associative algebra $\bar{W(n,m,m+s)}$) and we show that it is simple. We find the non-associative algebra automorphism group $Aut_{non}\bar{(W(1,0,0))}\;of\;\bar{W(1,0,0)}$. Also we find that any derivation of $\bar{W(1,0,0)}$ is a scalar derivation in this paper.

• The Journal of the Korean life insurance medical association
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• v.33 no.2
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• pp.15-17
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• 2014

All Korean people are eligible for National Health Insurance(NHI). But large non-coverage of NHI is a big problem. The origin of this problem is from medical fee schedules. NHI calculate all hospital income including insurance medical practice, non-insurance medical practice and non-medical income(i.e. a funeral hall, a parking lot, stores in hospital).

• Communications of the Korean Mathematical Society
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• v.29 no.4
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• pp.539-547
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• 2014

In this paper, we study two types 1-lightlike submanifolds M, so called lightlike hypersurface and half lightlike submanifold, of an indefinite Kaehler manifold $\bar{M}$ admitting non-metric ${\pi}$-connection. We prove that there exist no such two types 1-lightlike submanifolds of an indefinite Kaehler manifold $\bar{M}$ admitting non-metric ${\pi}$-connections.

• Bulletin of the Korean Mathematical Society
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• v.50 no.5
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• pp.1567-1586
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• 2013

In this paper, we study the Einstein multiply warped products with a semi-symmetric non-metric connection and the multiply warped products with a semi-symmetric non-metric connection with constant scalar curvature, we apply our results to generalized Robertson-Walker spacetimes with a semi-symmetric non-metric connection and generalized Kasner spacetimes with a semi-symmetric non-metric connection and find some new examples of Einstein affine manifolds and affine manifolds with constant scalar curvature. We also consider the multiply warped products with an affine connection with a zero torsion.

• Communications of the Korean Mathematical Society
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• v.32 no.4
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• pp.1047-1065
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• 2017

The notion of a non-metric ${\phi}$-symmetric connection on semi-Riemannian manifolds was introduced by Jin [6, 7]. The object of study in this paper is generic lightlike submanifolds of an indefinite Kaehler manifold ${\bar{M}}$ with a non-metric ${\phi}$-symmetric connection. First, we provide several new results for such generic lightlike submanifolds. Next, we investigate generic lightlike submanifolds of an indefinite complex space form ${\bar{M}}(c)$ with a non-metric ${\phi}$-symmetric connection.

• Journal of the Korean Mathematical Society
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• v.51 no.2
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• pp.311-323
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• 2014

In this paper, we construct two types of non-tangential half lightlike submanifolds of a semi-Riemannian manifold admitting a semi-symmetric non-metric connection. Our main result is to prove several characterization theorems for each types of such half lightlike submanifolds equipped with totally geodesic screen distributions.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.1156-1157
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.1118-1119
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• 2005