• Korean Journal of Mathematics
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• v.5 no.2
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• pp.135-139
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• 1997

We introduce the concepts of weakly prime and weakly semi-prime ideals in po-${\Gamma}$-semigroup and give some characterizations of weakly prime and weakly semi-prime ideals of po-${\Gamma}$-semigroups analogous to the characterizations of weakly prime and weakly semi-prime ideals of po-semigroups considered by N. Kehayopulu.

• East Asian mathematical journal
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• v.23 no.1
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• pp.45-58
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• 2007

The notions of IVF strongly semiopen (semiclosed) sets and IVF (strong) semi-interior (IVF (strong) semi-closure) are introduced, and several examples are provided. Related properties are investigated. In particular, characterizations of an IVF strongly semiopen set are discussed.

• 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.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.3
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• pp.421-424
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• 2009

In this paper, we introduce the concept of fuzzy semi-weakly r-semicontinuous mappings on a fuzzy topological space and study characterizations for such mappings. And we investigate the relationships among fuzzy r-semicontinuity, fuzzy semi-weakly r-semicontinuity and fuzzy weakly r-semicontinuity.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1997.11a
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• pp.47-51
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• 1997

In this paper, certain fuzzy semi-separation axioms are studied in terms of the notions of quasi-coincidence, fuzzy semi-q-neigborhoods and fuzzy semi-$\theta$-closure operators. Fuzzy semi-T2, fuzzy semi-Urysohn and fuzzy s-regular spaces are defined, and fuzzy spaces satisfying these axioms are characterized.

• The Pure and Applied Mathematics
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• v.19 no.3
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• pp.211-228
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• 2012

We study lightlike submanifolds M of a semi-Riemannian manifold $\bar{M}$ with a semi-symmetric non-metric connection subject to the conditions; (a) the characteristic vector field of $\bar{M}$ is tangent to M, (b) the screen distribution on M is totally umbilical in M and (c) the co-screen distribution on M is conformal Killing.

• The Mathematical Education
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• v.22 no.1
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• pp.31-33
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• 1983

In this paper, we investigate the properties of the semi-continuous functions on the first axiom space, n-th product space, pseudo-metric space, and proximity space. Counterexample is used when the converse of the theorem is not hold.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.4
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• pp.769-781
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• 2011

We study the geometry of half lightlike sbmanifolds M of a semi-Riemannian space form $\tilde{M}(c)$ admitting a semi-symmetric metric connection subject to the conditions: (1) The screen distribution S(TM) is totally umbilical (geodesic) and (2) the co-screen distribution $S(TM^{\bot})$ of M is a conformal Killing one.

• Journal of the Korean Mathematical Society
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• v.52 no.4
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• pp.781-795
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• 2015

Given a positive integer n, a ring R is said to be n-semi-Armendariz if whenever $f^n=0$ for a polynomial f in one indeterminate over R, then the product (possibly with repetitions) of any n coefficients of f is equal to zero. A ring R is said to be semi-Armendariz if R is n-semi-Armendariz for every positive integer n. Semi-Armendariz rings are a generalization of Armendariz rings. We characterize when certain important matrix rings are n-semi-Armendariz, generalizing some results of Jeon, Lee and Ryu from their paper (J. Korean Math. Soc. 47 (2010), 719-733), and we answer a problem left open in that paper.

• Transactions of Materials Processing
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• v.11 no.4
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• pp.312-322
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• 2002

In this study, an innovative semi-solid die casting technology to replace heavier cast iron compressor parts with lightweight aluminum castings was proposed, and the application possibility for home-appliance component was investigated. The most important factors regarding the semi-solid die casting process are the reheating process of the raw materials to the semi-solid state, specifications of the forming machine, the optimal injection conditions and die design. Materials used in this study were A3S7 and hSn alloys fabricated by the electromagnetic stirring process. The optimal injection conditions for semi-solid die casting process were Presented with the reheating conditions of the semi-solid materials. To investigate the effect of plunger tip shape on the formability and mechanical properties in semi-solid die casting process for complicated shape part, two kinds of plunger tip shape with long and short plunger tip taper are proposed.