• Proceedings of the KSME Conference
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• 2000.11a
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• pp.219-224
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• 2000

A research for development of composite body panel is in progress for lightening tare. Low specific weight LPMC (Low pressure molding compound) has advantages such as lightweight and resistance to dent and corrosion. In this study, tensile, bending and impact tests for the LPMC and SPRC35 (High tension steel plate) were carried out and compared. Although mechanical properties of SPRC35 are better than the LPMC, the LPMC satisfies basic requirements for car body panel. The high temperature exposed LPMC were degraded due to fiber-matrix debonding and deterioration of resin.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.109-114
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• 2000

A research fur development of composite body panel is in progress for lightening tare. In this study, experiments on estimation of mechanical properties of LPMC (Low pressure molding compound) including fatigue and impact characteristics were carried out. The experiments show that LPMC satisfied basic requirements of car body panel. The fatigue life of LPMC was predicted and the material degradation due to fatigue and impact were fined out.

• Journal of the Korean Mathematical Society
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• v.48 no.1
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• pp.1-12
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• 2011

The purpose of this paper is to study pseudo-Riemannian algebras, which are algebras with pseudo-Riemannian non-degenerate symmetric bilinear forms. We nd that pseudo-Riemannian algebras whose left centers are isotropic play a curial role and show that the decomposition of pseudo-Riemannian algebras whose left centers are isotropic into indecomposable non-degenerate ideals is unique up to a special automorphism. Furthermore, if the left center equals the center, the orthogonal decomposition of any pseudo-Riemannian algebra into indecomposable non-degenerate ideals is unique up to an isometry.

• Bulletin of the Korean Mathematical Society
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• v.54 no.3
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• pp.763-787
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• 2017

A graph is called 1-planar if it can be drawn in the Euclidean plane ${\mathbb{R}}^2$ such that each edge is crossed by at most one other edge. The weight of an edge is the sum of degrees of two ends. It is known that every planar graph of minimum degree ${\delta}{\geq}3$ has an edge with weight at most 13. In the present paper, we show the existence of edges with weight at most 25 in 3-connected 1-planar graphs.

• Bulletin of the Korean Mathematical Society
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• v.49 no.2
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• pp.353-358
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• 2012

In this paper, we focus on pseudo-Riemannian associative fermionic Novikov algebras. We prove that the underlying Lie algebras of pseudo-Riemannian associative fermionic Novikov algebras are 2-step nilpotent and that pseudo-Riemannian associative fermionic Novikov algebras are 3-step nilpotent. Moreover, we construct a pseudo-Riemannian associative fermionic Novikov algebra in dimension 14, which is not a Novikov algebra. It implies that the inverse proposition of Corollary 2 in the paper "Pseudo-Riemannian Novikov algebras" [J. Phys. A: Math. Theor. 41 (2008), 315207] does not hold.

• Journal of the Korean Mathematical Society
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• v.54 no.5
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• pp.1537-1556
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• 2017

In this paper, we introduce the notion of generating index ${\mathcal{I}}_1(A)$ (2-generating index ${\mathcal{I}}_2(A)$, resp.) of a left-symmetric algebra A, which is the maximum of the dimensions of the subalgebras generated by any element (any two elements, resp.). We give a classification of left-symmetric algebras with ${\mathcal{I}}_1(A)=1$ and ${\mathcal{I}}_2(A)=2$, 3 resp., and show that all such algebras can be constructed by linear and bilinear functions. Such algebras can be regarded as a generalization of those relating to the integrable (generalized) Burgers equation.

• Bulletin of the Korean Mathematical Society
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• v.54 no.3
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• pp.967-973
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• 2017

We prove that a homogeneous square Einstein Finsler metric is either Riemannian or flat.

• Journal of the Korean Mathematical Society
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• v.45 no.6
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• pp.1725-1740
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• 2008

In this paper, we introduce a fixed point index of weakly inward 1-set-contraction mappings. With the aid of the new index, we obtain some new fixed point theorems, nonzero fixed point theorems and multiple positive fixed points for this class of mappings. As an application of nonzero fixed point theorems, we discuss an eigenvalue problem.

• Bulletin of the Korean Mathematical Society
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• v.60 no.3
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• pp.747-762
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• 2023

ω-left-symmetric algebras contain left-symmetric algebras as a subclass and the commutator defines an ω-Lie algebra. In this paper, we classify ω-left-symmetric algebras in dimension 3 up to an isomorphism based on the classification of ω-Lie algebras and the technique of Lie algebras.

• Journal of the Korean Mathematical Society
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• v.43 no.4
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• pp.783-801
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• 2006

Let A be the mod p Steenrod algebra for p an arbitrary odd prime and S the sphere spectrum localized at p. In this paper, some useful propositions about the May spectral sequence are first given, and then, two new nontrivial homotopy elements ${\alpha}_1{\jmath}{\xi}_n\;(p{\geq}5,n\;{\geq}\;3)\;and\;{\gamma}_s{\alpha}_1{\jmath}{\xi}_n\;(p\;{\geq}\;7,\;n\;{\geq}\;4)$ are detected in the stable homotopy groups of spheres, where ${\xi}_n\;{\in}\;{\pi}_{p^nq+pq-2}M$ is obtained in [2]. The new ones are of degree 2(p - 1)($p^n+p+1$) - 4 and 2(p - 1)($p^n+sp^2$ + sp + (s - 1)) - 7 and are represented up to nonzero scalar by $b_0h_0h_n,\;b_0h_0h_n\tilde{\gamma}_s\;{\neq}\;0\;{\in}\;Ext^{*,*}_A^(Z_p,\;Z_p)$ in the Adams spectral sequence respectively, where $3\;{\leq}\;s\;<\;p-2$.