• Journal of the Korean housing association
• /
• v.8 no.1
• /
• pp.49-56
• /
• 1997

The purpose of this study was to identify effects of residential mobility among the new town movers. The major findings are as follows : 1) As they moved in new town the distance to their wok palce increased substantially. 2) Degree of residential satisfactions increased after moving in the new town. 3) Commuting time is strongly influenced by head of household's level of education, family life span, and tenure status of households.

• Bulletin of the Korean Mathematical Society
• /
• v.54 no.6
• /
• pp.2013-2027
• /
• 2017

We compute explicitly the matrices represented by Toeplitz operators on the Hardy space over the unit circle with respect to a special orthonormal basis constructed by author in terms of their symbols. And we also find a necessary condition for the matrix generated by the product of two Toeplitz operators with respect to the basis to be a Toeplitz matrix by a direct calculation and we finally solve commuting problems of two Toeplitz operators in terms of symbols. This is a generalization of the classical results obtained regarding to the orthonormal basis consisting of the monomials.

• Journal of the Korean Mathematical Society
• /
• v.38 no.2
• /
• pp.193-226
• /
• 2001

We study Feynman's Operational Calculus for operator-valued functions of time and for measures which are not necessarily probability measures; we also permit the presence of certain unbounded operators. further, we relate the disentangling map defined within the solutions of evolution equations and, finally, remark on the application of stability results to the present paper.

• Bulletin of the Korean Mathematical Society
• /
• v.54 no.2
• /
• pp.633-646
• /
• 2017

Recently, Curto, Lee and Yoon considered the properties (such as, hyponormality, subnormality, and flatness, etc.) for 2-variable weighted shifts and constructed several families of commuting pairs of subnormal operators such that each family can be used to answer a conjecture of Curto, Muhly and Xia negatively. In this paper, we consider the weak and quadratic hyponormality of 2-variable weighted shifts ($W_1,W_2$). In addition, we detect the weak and quadratic hyponormality with some interesting 2-variable weighted shifts.

• Bulletin of the Korean Mathematical Society
• /
• v.45 no.4
• /
• pp.671-680
• /
• 2008

Necessary conditions for the existence of common fixed points for noncommuting mappings satisfying generalized contractive conditions in a Menger convex metric space are obtained. As an application, related results on best approximation are derived. Our results generalize various well known results.

• Honam Mathematical Journal
• /
• v.39 no.2
• /
• pp.143-159
• /
• 2017

In this paper, we show that algebraic properties of Toeplitz operators on both Bergman spaces and Hardy spaces on the unit disc essentially generalizes on arbitrary bounded domains in the plane. In particular, we obtain results for the uniqueness property and commuting problems of the Toeplitz operators on the Hardy and the Bergman spaces associated to bounded domains.

• Journal of the Chungcheong Mathematical Society
• /
• v.18 no.1
• /
• pp.1-22
• /
• 2005

The object of this paper is to introduce the concept of a pair of semi-compatible self-maps in a fuzzy metric space to establish a fixed point theorem for four self-maps. It offers an extension of Vasuki [10] to four self-maps under the assumption of semi-compatibility and compatibility, repsectively. At the same time, these results give the alternate results of Grebiec [5] and Vasuki [9] as well.

• Journal of applied mathematics & informatics
• /
• v.30 no.1_2
• /
• pp.265-278
• /
• 2012

In this work we have considered several common fixed point results in metric spaces for weak compatible mappings. By applications of these results we establish some fixed point theorems in fuzzy metric spaces.

• Journal of the Chungcheong Mathematical Society
• /
• v.22 no.3
• /
• pp.375-382
• /
• 2009

Several common stationary point theorems for two classes of contractive type multivalued mappings in a complete bounded metric space are given. The results presented in this paper generalize and extend some known results in literature.

• Journal of applied mathematics & informatics
• /
• v.6 no.1
• /
• pp.239-246
• /
• 1999

The purpose of this paper is to prove the following result: Let R be a 2-torsion free noncommutative semi-prime ring and D:RlongrightarrowR a derivation. Suppose that $[[D(\chi),\chi],\chi]\in$ Z(R) holds for all $\chi \in R$. Then D is commuting on R.