• 대한수학회지
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• 제37권4호
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• pp.645-655
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• 2000

We calculate the R(G)-algebra structure on the reduced equivariant K-groups of two-dimensional spheres on which a compact Lie group G acts as a reflection. In particular, the reduced equivariant K-groups are trivial if G is abelian, which shows that the previous Y. Yang's calculation in [8] is incorrect.

• 대한수학회보
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• 제43권4호
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• pp.841-846
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• 2006

Suppose that F is a closed t-aspherical PL n-manifold with finite, sparsely abelian ${\pi}_1(F)$ and A is a closed aspherical PL m-manifold with hopfian, normally cohopfian ${\pi}_1(A)$. If $X(F){\neq}0{\neq}X(A)$, then $F{\times}A$ is a codimension-(t+1) PL fibrator.

• 대한수학회보
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• 제43권4호
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• pp.763-770
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• 2006

Let X be a four-dimensional projective variety defined over the field of complex numbers with only terminal singularities. We prove that if the intersection number of the canonical divisor K with every very general curve is positive (K is almost numerically positive) then every very general proper subvariety of X is of general type in ';he viewpoint of geometric Kodaira dimension. We note that the converse does not hold for simple abelian varieties.

• 대한수학회지
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• 제48권5호
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• pp.927-938
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• 2011

Let G be an abelian monoid with identity e. Let R be a G-graded commutative ring, and M a graded R-module. In this paper we first introduce the concept of graded primal submodules of M an give some basic results concerning this class of submodules. Then we characterize the graded primal ideals of the idealization R(+)M.

• 대한수학회논문집
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• 제33권4호
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• pp.1103-1112
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• 2018

We study the structure of a generalization of right nilpotent-duo rings in relation with powers of elements. Such a ring property is said to be weakly right nilpotent-duo. We find connections between weakly right nilpotent-duo and weakly right duo rings, in several algebraic situations which have roles in ring theory. We also observe properties of weakly right nilpotent-duo rings in relation with their subrings and extensions.

• 대한수학회보
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• 제57권1호
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• pp.195-206
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• 2020

The fundamental idea of this article is to present an effective way to obtain the large groups in terms of the split extension obtained by a finite cyclic group and a free abelian group rank 2. The proof of the main result on largeness property of this specific split extension groups will be given by using the connection of large groups with the groups having deficiency one presentations.

• Korean Journal of Mathematics
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• 제14권2호
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• pp.227-232
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• 2006

We study some dynamical properties in the context of bitransformation groups, and show that if (H,X,T) is a bitransformation group such that (H,X) is almost periodic and (X/H,T) is pointwise almost periodic $T_2$ and $x{\in}X$, then $E_x=\{q{\in}E(H,X){\mid}qx{\in}{\overline{xT}\}$ is a compact $T_2$ topological group and $E_{qx}=E_x(q{\in}E(H,X))$ when H is abelian, where E(H,X) is the enveloping semigroup of the transformation group (H,X).

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제6권1호
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• pp.1-8
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• 1999

Let $K_{\alpha}(G)$ (resp. $K_s(G)$) be the abelian (resp. symmetric) Kac algebra for a locally compact group G. We show that there exists a one-to-one correspondence between the subgroups of G and the sub-Kac algebras of $K_{\alpha}(G)$ (resp. $K_s(G)$). Moreover we obtain similar correspondences between the subgroups of G and the reduced Kac algebras of $K_{\alpha}(G)$ (resp. $K_s(G)$).

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제4권1호
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• pp.93-96
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• 1997

An atomic integral domain R is a half-factorial domain (HFD) if whenever $\chi_1$… $\chi_{m}=y_1$…$y_n$ with each $\chi_{i},y_j \in R$ irreducible, then m = n. In this paper, we show that if R[X] is an HFD, then $Cl_{t}(R)$ $\cong$ $Cl_{t}$(R[X]), and if $G_1$ and $G_2$ are torsion abelian groups, then there exists a Dedekind HFD R such that Cl(R) = $G_1\bigoplus\; G_2$.

• 한국수학교육학회지시리즈A:수학교육
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• 제12권1호
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• pp.1-3
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• 1973

In this paper, we want to verify some properties in tensor product. It is interesting to think semi-exact sequence in tensor Product by [3]. Moreover no hardness is there in process and we want to discuss the commutativity in tensor product. For a certain semi-exact sequence, if we product arbitrary Abelian group for each group then the tensor Product will do or not. Here, we have positive answer. At first we define the semi-exact sequence as following.