• 대한수학회논문집
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• 제35권4호
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• pp.1269-1281
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• 2020

In this article, we show that a pseudo-Hermitian magnetic curve in a normal almost contact metric 3-manifold equipped with the canonical affine connection ${\hat{\nabla}}^t$ is a slant helix with pseudo-Hermitian curvature ${\hat{\kappa}}={\mid}q{\mid}\;sin\;{\theta}$ and pseudo-Hermitian torsion ${\hat{\tau}}=q\;cos\;{\theta}$. Moreover, we prove that every pseudo-Hermitian magnetic curve in normal almost contact metric 3-manifolds except quasi-Sasakian 3-manifolds is a slant helix as a Riemannian geometric sense. On the other hand we will show that a pseudo-Hermitian magnetic curve γ in a quasi-Sasakian 3-manifold M is a slant curve with curvature κ = |(t - α) cos θ + q| sin θ and torsion τ = α + {(t - α) cos θ + q} cos θ. These curves are not helices, in general. Note that if the ambient space M is an α-Sasakian 3-manifold, then γ is a slant helix.

• East Asian mathematical journal
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• 제30권3호
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• pp.371-383
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• 2014

We study the geometry of lightlike submanifolds of a semi-Riemannian manifold. The purpose of this paper is to prove two singular theorems for irrotational lightlike submanifolds M of a semi-Riemannian space form $\bar{M}(c)$ admitting a semi-symmetric non-metric connection such that the structure vector field of $\bar{M}(c)$ is tangent to M.

• 호남수학학술지
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• 제35권4호
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• pp.757-764
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• 2013

In this paper, we give sufficient conditions for a map with nonconvex values to have a continuous selection and the selection extension property in LC-metric spaces under the one-point extension property. And we apply it to weakly lower semicontinuous maps and generalize previous results. We also get a continuous selection theorem for almost lower semicontinuous maps with closed sub-admissible values in $\mathbb{R}$-trees.

• East Asian mathematical journal
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• 제27권1호
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• pp.1-9
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• 2011

In this paper, we consider an iterative scheme for finding a common element of the set of fixed points of a asymptotically quasi nonexpansive mapping and the set of solutions of the variational inequality for an inverse strongly monotone mapping in a Hilbert space. Then we show that the sequence converges strongly to a common element of two sets. Using this result, we consider the problem of finding a common fixed point of a asymptotically quasi-nonexpansive mapping and strictly pseudocontractive mapping and the problem of finding a common element of the set of fixed points of a asymptotically quasi-nonexpansive mapping and the set of zeros of an inverse-strongly monotone mapping.

• 대한수학회논문집
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• 제29권2호
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• pp.331-343
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• 2014

The object of the present paper is to study a semi-symmetric metric connection in an (${\varepsilon}$)-Kenmotsu manifold. In this paper, we study a semi-symmetric metric connection in an (${\varepsilon}$)-Kenmotsu manifold whose projective curvature tensor satisfies certain curvature conditions.

• 호남수학학술지
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• 제1권1호
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• pp.27-34
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• 1979

근래(近來) Skorokhod는 확률론(確率論)의 극한문제(極限問題)와 관련(關聯)하여 모든 불연속함수공간(不連續函數空間)에 관(關)한 위상(位相)을 정의(定義)하였다. 본(本) 논문(論文)에서는 Skorokhod 수렴위상(收斂位相)을 쌍위상(雙位相)(bitopology)형(型)으로 일반화(一般化)하고 잘 알려져 있는 여러위상(位相)과 비교(比較)하여 다음과 같은 결과(結果)를 새로 얻었다. (정리(定理) 2-11); 공간(空間) X와 Y가 완비준거이가분공간(完備準距離可分空間) (Completdy quasi-metric separable space)이라면 쌍개수렴위상(雙槪收斂位相)(pairwise almost convergent topology)는 Skorokhod 쌍수렴위상(雙收斂位相) 보다 약(弱)하다. 그리고 (정리(定理) 2-12); 쌍(雙) graph 위상(位相)은 Skorokhod $J_1$-수렴위상(收斂位相)과 일치(一致)한다. 끝으로 주정리(主定理)인 (정리(定理( 3-1)과 (정리(定理) 3-2)에서 Skorokhod 쌍수렴위상(雙收斂位相)의 Compact성(性)에 관(關)한 필요충분조건(必要充分條件)을 밝혔다.