• Kyungpook Mathematical Journal
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• v.63 no.3
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• pp.507-519
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• 2023

The aim of this paper is to study the Fisher-Marsden conjucture in the frame work of f-cosymplectic and (k, µ)-cosymplectic manifolds. First we prove that a compact f-cosymplectic manifold satisfying the Fisher-Marsden equation R'^*_g = 0 is either Einstein manifold or locally product of Kahler manifold and an interval or unit circle S¹. Further we obtain that in almost (k, µ)-cosymplectic manifold with k < 0, the Fisher-Marsden equation has a trivial solution.

• Honam Mathematical Journal
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• v.37 no.4
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• pp.457-468
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• 2015

The aim of present paper is to investigate 3-dimensional ${\xi}$-projectively flt and $\tilde{\varphi}$-projectively flt normal almost paracontact metric manifolds. As a first step, we proved that if the 3-dimensional normal almost paracontact metric manifold is ${\xi}$-projectively flt then ${\Delta}{\beta}=0$. If additionally ${\beta}$ is constant then the manifold is ${\beta}$-para-Sasakian. Later, we proved that a 3-dimensional normal almost paracontact metric manifold is $\tilde{\varphi}$-projectively flt if and only if it is an Einstein manifold for ${\alpha},{\beta}=const$. Finally, we constructed an example to illustrate the results obtained in previous sections.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.3
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• pp.223-230
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• 2004

A method for measuring array manifold which is the array antenna response of incident signal is presented. Array manifold measurement procedure by the presented method is explained for UCA(Uniform Circular Array), and spatial spectrum of 300 ㎒ tone signal incident on UCA is estimated by MUSIC algorithm in which spatial spectrum peak is searched with measured array manifold. Spatial spectrum estimation using array manifold measured by the proposed method shows superior performance to calculated array manifold.

• Journal of Ocean Engineering and Technology
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• v.29 no.3
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• pp.207-216
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• 2015

Amanifold is one of the essential subsea oil and gas production components to simplify the subsea production layout. It collects the production fluid from a couple of wellheads, transfers it to onshore or offshore storage platforms, and even accommodates water and gas injection flowlines. This paper presents the basic design procedure for a manifold frame structure with novel structural verification using in-house unity check codes. Loads and load cases for the design of an SIL 3 class-manifold are established from a survey of relevant industrial codes. The basic design of the manifold frame is developed based on simple load considerations such as the self weights of the manifold frame and pipeline system. In-house software with Eurocode 3 embedded, called INHA-SOLVER, makes it possible to carry out code checks on the yield and buckling unities. This paper finally proves that the new design of the manifold frame structure is effective to resist a permanent and environment load, and the in-house code is also adaptively combined with the commercial finite element code Nastran.

• Communications of the Korean Mathematical Society
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• v.38 no.3
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• pp.893-900
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• 2023

In the present study, we consider some curvature properties of generalized B-curvature tensor on Kenmotsu manifold. Here first we describe certain vanishing properties of generalized B curvature tensor on Kenmostu manifold. Later we formulate generalized B pseudo-symmetric condition on Kenmotsu manifold. Moreover, we also characterize generalized B ϕ-recurrent Kenmotsu manifold.

• Korean Journal of Computational Design and Engineering
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• v.5 no.4
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• pp.293-300
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• 2000

The non-manifold geometric modeling technique is to improve design process and to Integrate design, analysis, and manufacturing by handling mixture of wireframe model, surface model, and solid model in a single data structure. For the non-manifold geometric modeling, Euler operators and other high level modeling methods are necessary. Boolean operation is one of the representative modeling method for the non-manifold geometric modeling. This thesis studies Boolean operations of non-manifold model with the data structure of selective storage. The data structure of selective storage is improved non-manifold data structure in that existing non-manifold data structures using ordered topological representation method always store non-manifold information even if edges and vortices are in the manifold situation. To implement Boolean operations for non-manifold model, intersection algorithm for topological cells of three different dimensions, merging and selection algorithm for three dimensional model, and Open Inventor(tm), a 3D toolkit from SGI, are used.

• Journal of the Korean Mathematical Society
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• v.32 no.3
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• pp.553-562
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• 1995

In a Recent paper [3], D. Chinea, M. Delon and J. C. Marrero proved that a cosymplectic manifold is formal and constructed an example of compact cosymplectic manifold which is not a global product of a Kaehler manifold with the circle. In this paper we study the compact cosymplectic manifolds with critical Riemannian metrics.

• Kyungpook Mathematical Journal
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• v.55 no.3
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• pp.731-739
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• 2015

The object of the present paper is to characterize a Riemannian manifold admitting a type of semi-symmetric non-metric connection.

• Honam Mathematical Journal
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• v.44 no.3
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• pp.432-446
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• 2022

This article introduces the structure of GCR-lightlike submanifolds of an indefinite Kaehler statistical manifold and derives their geometric properties. The characterizations on totally geodesic, mixed geodesic, D-geodesic and D'-geodesic GCR-lightlike submanifolds have also been obtained.

• Honam Mathematical Journal
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• v.32 no.3
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• pp.363-374
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• 2010

We define a semi-symmetric metric connection in an almost r-paracontact Riemannian manifold and we consider submanifolds of an almost r-paracontact Riemannian manifold endowed with a semi-symmetric metric connection and obtain Gauss and Codazzi equations, Weingarten equation and curvature tensor for submanifolds of an almost r-paracontact Riemannian manifold endowed with a semi-symmetric metric connection.