• 대한수학회보
• /
• 제55권5호
• /
• pp.1351-1370
• /
• 2018

In the first part of this paper we show that, under some conditions, a polynomially demicompact operator can be demicompact. An example involving the Caputo fractional derivative of order ${\alpha}$ is provided. Furthermore, we give a refinement of the left and the right Weyl essential spectra of a closed linear operator involving the class of demicompact ones. In the second part of this work we provide some sufficient conditions on the inputs of a closable block operator matrix, with domain consisting of vectors which satisfy certain conditions, to ensure the demicompactness of its closure. Moreover, we apply the obtained results to determine the essential spectra of this operator.

• Korean Journal of Mathematics
• /
• 제24권2호
• /
• pp.139-168
• /
• 2016

In this work, we rst introduce a class of analytic functions involving the Dziok-Srivastava linear operator that generalizes the class of uniformly starlike functions with respect to symmetric points. We then establish the closure of certain well-known integral transforms under this analytic function class. This behaviour leads to various radius results for these integral transforms. Some of the interesting consequences of these results are outlined. Further, the lower bounds for the ratio between the functions f(z) in the class under discussion, their partial sums $f_m(z)$ and the corresponding derivative functions f'(z) and $f^{\prime}_m(z)$ are determined by using the coecient estimates.

• 대한수학회지
• /
• 제44권2호
• /
• pp.261-273
• /
• 2007

In this paper, we introduce some new properties of a topological space which are respectively generalizations of $Fr\'{e}chet$-Urysohn property. We show that countably AP property is a sufficient condition for a space being countable tightness, sequential, weakly first countable and symmetrizable, to be ACP, $Fr\'{e}chet-Urysohn$, first countable and semimetrizable, respectively. We also prove that countable compactness is a sufficient condition for a countably AP space to be countably $Fr\'{e}chet-Urysohn$. We then show that a countably compact space satisfying one of the properties mentioned here is sequentially compact. And we show that a countably compact and countably AP space is maximal countably compact if and only if it is $Fr\'{e}chet-Urysohn$. We finally obtain a sufficient condition for the ACP closure operator $[{\cdot}]_{ACP}$ to be a Kuratowski topological closure operator and related results.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제11권3호
• /
• pp.243-265
• /
• 2004

In this paper, we introduce the fundamental concepts of intuitionistic fuzzy Q-neighborhood, intuitionistic Q-first axiom of countability, intuitionistic first axiom of countability, intuitionistic fuzzy closure operator, intuitionistic fuzzy boundary point and intuitionistic fuzzy accumulation point and investigate some of their properties.

• 대한수학회논문집
• /
• 제25권2호
• /
• pp.273-282
• /
• 2010

The concept of intuitionistic fuzzy $\theta$-interior operator is introduced and discussed in intuitionistic fuzzy topological spaces. As applications of this concept, intuitionistic fuzzy strongly $\theta$-continuous, intuitionistic fuzzy $\theta$-continuous, and intuitionistic fuzzy weakly continuous functions are characterized in terms of intuitionistic fuzzy $\theta$-interior operator.

• 대한수학회보
• /
• 제43권4호
• /
• pp.671-677
• /
• 2006

Let $A, B{\in}B(H)$ be Hilbert space contractions, and let ${\Delta}_{AB}$ be the elementary operator ${\Delta}_{AB}:X{\rightarrow}AXB-X$. A number of conditions which are equivalent to '${\Delta}_{AB}$ has closed range' are proved.

• Korean Journal of Mathematics
• /
• 제27권4호
• /
• pp.1109-1118
• /
• 2019

In this paper, we introduce the notion of residuated and Galois connections on adjoint triples and investigate their properties. Using the properties of residuated and Galois connections, we solve fuzzy relation equations and give their examples.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제12권1호
• /
• pp.75-91
• /
• 2005

The main objective of this paper is to introduce the gradation of neigh-bourhoodness in L-fuzzy topology and to introduce the fuzziness in the concept of convergence of L-fuzzy nets.

• 인터넷정보학회논문지
• /
• 제23권2호
• /
• pp.19-28
• /
• 2022

본 연구는 스마트 기기의 푸시 알림을 이용하여 식당의 휴무를 설정 및 제공하는 안내 시스템을 제안한다. 식당 운영자는 제안 애플리케이션의 푸시 알림을 통하여 일주일 동안의 가게 휴무 일정을 설정 및 수정 할 수 있으며, 식당 이용자는 제안 애플리케이션을 통해 식당의 정보와 휴무 여부를 알 수 있다. 제안 방법은 휴무 정보 제공을 위한 서버 시스템을 이용하며, 제안 애플리케이션은 매일 아침 식당 운영자에게 푸시 알림을 수행하여 당일 매장 휴무를 한 번 더 확인한다. 제안 시스템의 효용성을 확인하기 위해 휴무 관리 애플리케이션, 이용자 애플리케이션 및 서버 시스템을 구축하여 식당 휴무 안내 실험을 하였으며, 그 결과 96%의 영업시간 확인함을 나타냈다. 그리고 기존 정보 제공 서비스와의 비교 실험에서 제안 방법이 보다 우수함을 확인하였다. 즉, 제안 방법은 식당 운영자와 식당 사용자에게 손쉽게 휴무 정보를 공유할 수 있는 생활에 유용한 서비스 시스템이 될 것이다.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• 제8권1호
• /
• pp.6-10
• /
• 2008

In this paper, we introduce the concept of fuzzy (r, s)-adherence points, fuzzy (r, s)-accumulation points and fuzzy (r, s)-derived sets in double fuzzy topology. We investigate some of their properties. The relationship with double fuzzy closure operator was studied.