• 호남수학학술지
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• 제36권2호
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• pp.339-344
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• 2014

In this paper, we give some properties on projective modules, locally cyclic projective modules and the ideal ${\tau}(M)$.

• 대한수학회지
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• 제58권2호
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• pp.473-486
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• 2021

We prove non-existence of real hypersurfaces with Killing structure Jacobi operator in complex projective spaces. We also classify real hypersurfaces in complex projective spaces whose structure Jacobi operator is Killing with respect to the k-th generalized Tanaka-Webster connection.

• Korean Journal of Mathematics
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• 제17권4호
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• pp.429-436
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• 2009

We define a projective representation $M_1{^{\rightarrow}_{\rightarrow}}M_2{\rightarrow}M_3$ of a quiver $Q={\bullet}{^{\rightarrow}_{\rightarrow}}{\bullet}{\rightarrow}{\bullet}$ and consider their properties. Then we show that any projective representation $M_1{^{\rightarrow}_{\rightarrow}}M_2{\rightarrow}M_3$ of a quiver $Q={\bullet}{^{\rightarrow}_{\rightarrow}}{\bullet}{\rightarrow}{\bullet}$ is isomorphic to the quotient of a direct sum of projective representations $0{^{\rightarrow}_{\rightarrow}}0{\rightarrow}P,\;0{^{\rightarrow}_{\rightarrow}}P{\rightarrow\limits^{id}}P$ and $P{^{\rightarrow}_{\rightarrow}}^{e1}_{e2}P{\oplus}P{\rightarrow\limits^{id_{P{\oplus}P}}}P{\oplus}P$, where $e_1(a)=(a,0)$ and $e_2(a)=(0,a)$.

• Korean Journal of Mathematics
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• 제17권3호
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• pp.271-281
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• 2009

We define injective and projective representations of a quiver $Q={\bullet}{\rightarrow}{\bullet}{\rightarrow}{\bullet}$. Then we show that a representation $M_1\longrightarrow[50]^{f1}M_2\longrightarrow[50]^{f2}M_3$ of a quiver $Q={\bullet}{\rightarrow}{\bullet}{\rightarrow}{\bullet}$ is projective if and only if each $M_1,\;M_2,\;M_3$ is projective left R-module and $f_1(M_1)$ is a summand of $M_2$ and $f_2(M_2)$ is a summand of $M_3$. And we show that a representation $M_1\longrightarrow[50]^{f1}M_2\longrightarrow[50]^{f2}M_3$ of a quiver $Q={\bullet}{\rightarrow}{\bullet}{\rightarrow}{\bullet}$ is injective if and only if each $M_1,\;M_2,\;M_3$ is injective left R-module and $ker(f_1)$ is a summand of $M_1$ and $ker(f_2)$ is a summand of $M_2$.

• Management Science and Financial Engineering
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• 제7권1호
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• pp.27-39
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• 2001

The multi-projective model considers attributes and the relationships among attributes called projections. The critical features of the multi-projective model are the way of relating attributes in the description of the system, the way of reasoning incomplete projections, and the determination of connected patterns between projection. In order to get a full picture of the system, we build a set of projections. The multi-projective model can be thought of as projections of a multi-dimensional reality onto simplified “model space”. The multi-projective database modeling approach used in this paper unified the ideas and terminology of various database models. Most importantly, the multi-projective modeling is presented as a tool of database design in the relational and other database models.

• International Journal of Contents
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• 제12권2호
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• pp.1-5
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• 2016

Extensible 3D (X3D) is the ISO standard for defining 3D interactive web- and broadcast-based 3D content integrated with multimedia. With the advent of this integration of interactive 3D graphics into the web, users can easily produce 3D scenes within web contents. Even though there are diverse texture nodes in X3D, projective textures are not provided. We enable X3D to provide SingularProjectiveTexture and MultiProjectiveTexture nodes by materializing independent nodes of projector nodes for a singular projector and multi-projector. Our approach takes the creation of an independent projective texture node instead of Kamburelis's method, which requires inconvenient and duplicated specifications of two nodes, ImageTexture and Texture Coordinate.

• 대한수학회지
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• 제58권6호
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• pp.1513-1528
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• 2021

Let R be a commutative ring with prime nilradical Nil(R) and M an R-module. Define the map 𝜙 : R → R_Nil(R) by ${\phi}(r)=\frac{r}{1}$ for r ∈ R and 𝜓 : M → M_Nil(R) by ${\psi}(x)=\frac{x}{1}$ for x ∈ M. Then 𝜓(M) is a 𝜙(R)-module. An R-module P is said to be 𝜙-projective if 𝜓(P) is projective as a 𝜙(R)-module. In this paper, 𝜙-exact sequences and 𝜙-projective R-modules are introduced and the rings over which all R-modules are 𝜙-projective are investigated.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.145-155
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• 2002

In this paper we study the rooted loopless maps on the sphere and the projective plane with the valency of root-face and the number of edges as parameters. Explicit expression of enumerating function is obtained for such maps on the sphere and the projective plane. A parametric expression of the generating function is obtained for such maps on the projective plane, from which asymptotic evaluations are derived.

• 대한수학회지
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• 제55권1호
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• pp.1-16
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• 2018

In this paper, we give characteristic differential equations of a kind of projective vector fields on Finsler manifolds. Using these equations, we prove the vanishing theorem of projective vector fields on any compact Finsler manifold with the negative mean Ricci curvature, which is defined in [10]. This result involves the vanishing theorem of Killing vector fields in the Riemannian case and the work of [1, 14].

• 한국수학사학회지
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• 제15권1호
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• pp.1-14
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• 2002

This paper treats the history of the fundament of projective geometry Especially we introduce the essence of the framework of Karl Chirstian von Staudt's ‘Geometrie der Lage’. Von Staudt used axiomatical method to bum the system of the projective geometry, and proved the fundamental theorem of projective geometry. And he handled imaginary elements (or the first time in synthetic projective geometry.