• 대한수학회보
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• 제59권3호
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• pp.757-780
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• 2022

In this article, we study the weak and extra-weak type integral inequalities for the modified integral Hardy operators. We provide suitable conditions on the weights ω, ρ, φ and ψ to hold the following weak type modular inequality $${\mathcal{U}}^{-1}\({\int_{{\mid}{\mathcal{I}}f{\mid}>{\gamma}}}\;{\mathcal{U}}({\gamma}{\omega}){\rho}\){\leq}{\mathcal{V}}^{-1}\({\int}_{0}^{\infty}{\mathcal{V}}(C{\mid}f{\mid}{\phi}){\psi}\),$$ where ${\mathcal{I}}$ is the modified integral Hardy operators. We also obtain a necesary and sufficient condition for the following extra-weak type integral inequality $${\omega}\(\{{\left|{\mathcal{I}}f\right|}>{\gamma}\}\){\leq}{\mathcal{U}}{\circ}{\mathcal{V}}^{-1}\({\int}_{0}^{\infty}{\mathcal{V}}\(\frac{C{\mid}f{\mid}{\phi}}{{\gamma}}\){\psi}\).$$ Further, we discuss the above two inequalities for the conjugate of the modified integral Hardy operators. It will extend the existing results for the Hardy operator and its integral version.

• ETRI Journal
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• 제44권4호
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• pp.588-598
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• 2022

Since multi-access edge computing (MEC) was established as a key enabler of 5G, MEC based on 5G networks (5G MEC) has been perceived as a new business opportunity for many industry players, including telecom operators. Numerous 5G MEC cooperation announcements among companies playing their respective roles in the MEC ecosystem have been recently released. However, because of cooperative and competitive relationships among key players in the MEC ecosystem and the uncertainty of 5G MEC, the announcement of 5G MEC cooperation can negatively affect the telecom operators' firm value. This study investigates the market reaction to announcements of 5G MEC cooperation for telecom operators using an event study methodology. The empirical results show that announcements of 5G MEC cooperation have a negative impact on the telecom operators' firm value. The results also show that the early deployment of 5G networks may reduce the negative impact of 5G MEC cooperation announcements by reducing uncertainty.

• 대한수학회논문집
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• 제38권2호
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• pp.401-430
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• 2023

In this paper, we prove L^p estimates of a class of singular integral operators on product domains along surfaces defined by mappings that are more general than polynomials and convex functions. We assume that the kernels are in L(log L)² (𝕊^n-1 × 𝕊^m-1). Furthermore, we prove L^p estimates of the related class of Marcinkiewicz integral operators. Our results extend as well as improve previously known results.

• Korean Journal of Mathematics
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• 제31권1호
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• pp.109-120
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• 2023

The Berezin symbol à of an operator A on the reproducing kernel Hilbert space 𝓗 (Ω) over some set Ω with the reproducing kernel k_λ is defined by $${\tilde{A}}(\lambda)=\,\;{\lambda}{\in}{\Omega}$$. The Berezin number of an operator A is defined by $$ber(A):=\sup_{{\lambda}{\in}{\Omega}}{\mid}{\tilde{A}}({\lambda}){\mid}$$. We study some problems of operator theory by using this bounded function Ã, including estimates for Berezin numbers of some operators, including truncated Toeplitz operators. We also prove an operator analog of some Young inequality and use it in proving of some inequalities for Berezin number of operators including the inequality ber (AB) ≤ ber (A) ber (B), for some operators A and B on 𝓗 (Ω). Moreover, we give in terms of the Berezin number a necessary condition for hyponormality of some operators.

• Nuclear Engineering and Technology
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• 제37권5호
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• pp.491-502
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• 2005

Reliable human performance is a prerequisite in securing the safety of complicated process systems such as nuclear power plants. However, the amount of available knowledge that can explain why operators deviate from an expected performance level is so small because of the infrequency of real accidents. Therefore, in this study, a database that contains a set of useful information extracted from simulated emergencies was developed in order to provide important clues for understanding the change of operators' performance under stressful conditions (i.e., real accidents). The database was developed under Microsoft Windows TM environment using Microsoft Access $97^{TM}$ and Microsoft Visual Basic $6.0^{TM}$. In the database, operators' performance data obtained from the analysis of over 100 audio-visual records for simulated emergencies were stored using twenty kinds of distinctive data fields. A total of ten kinds of operators' performance data are available from the developed database. Although it is still difficult to predict operators' performance under stressful conditions based on the results of simulated emergencies, simulation studies remain the most feasible way to scrutinize performance. Accordingly, it is expected that the performance data of this study will provide a concrete foundation for understanding the change of operators' performance in emergency situations.

• 대한수학회지
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• 제51권5호
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• pp.1089-1104
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• 2014

An operator $T{\in}L(H)$, is said to belong to k-quasi class $A_n^*$ operator if $$T^{*k}({\mid}T^{n+1}{\mid}^{\frac{2}{n+1}}-{\mid}T^*{\mid}^2)T^k{\geq}O$$ for some positive integer n and some positive integer k. First, we will see some properties of this class of operators and prove Weyl's theorem for algebraically k-quasi class $A_n^*$. Second, we consider the tensor product for k-quasi class $A_n^*$, giving a necessary and sufficient condition for $T{\otimes}S$ to be a k-quasi class $A_n^*$, when T and S are both non-zero operators. Then, the existence of a nontrivial hyperinvariant subspace of k-quasi class $A_n^*$ operator will be shown, and it will also be shown that if X is a Hilbert-Schmidt operator, A and $(B^*)^{-1}$ are k-quasi class $A_n^*$ operators such that AX = XB, then $A^*X=XB^*$. Finally, we will prove the spectrum continuity of this class of operators.

• 한국정보처리학회논문지
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• 제6권1호
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• pp.21-31
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• 1999

이 논문은 시공간 데이터의 통합된 연산을 위하여 공간 연산자와 시간 연산자의 경합 접속을 연구한다. 시공간 연산을 위한 통합 연구는 시공간 참조 메크로에 의한 시공간 위상관계 연산자의공통 사용을 의미한다. 또한 이 논문은 지형 객체의 이력 정보를 검색하는 이력 연산자와 시간관계 비교 연산자의 통합 알고리즘을 제안한다. 제안된 확장 알고리즘은 기존의 GIS(Geographic Information System) 공간 데이터베이스를 기반으로 구현되며, 아울러 시공간 질의표현의 예를 통해 평가된다. 여기서 연구된 시공간 연산자의 통합은 통일된 시공간 질의를 지원하는데 유용한 기반구조를 제공할 것이다.

• Kyungpook Mathematical Journal
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• 제55권1호
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• pp.63-71
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• 2015

Let H be a separable infinite dimensional complex Hilbert space, and let $\mathcal{L}(H)$ denote the algebra of all bounded linear operators on H into itself. Let $A,B{\in}\mathcal{L}(H)$ we define the generalized derivation ${\delta}_{A,B}:\mathcal{L}(H){\mapsto}\mathcal{L}(H)$ by ${\delta}_{A,B}(X)=AX-XB$, we note ${\delta}_{A,A}={\delta}_A$. If the inequality ${\parallel}T-(AX-XA){\parallel}{\geq}{\parallel}T{\parallel}$ holds for all $X{\in}\mathcal{L}(H)$ and for all $T{\in}ker{\delta}_A$, then we say that the range of ${\delta}_A$ is orthogonal to the kernel of ${\delta}_A$ in the sense of Birkhoff. The operator $A{\in}\mathcal{L}(H)$ is said to be finite [22] if ${\parallel}I-(AX-XA){\parallel}{\geq}1(*)$ for all $X{\in}\mathcal{L}(H)$, where I is the identity operator. The well-known inequality (*), due to J. P. Williams [22] is the starting point of the topic of commutator approximation (a topic which has its roots in quantum theory [23]). In [16], the author showed that a paranormal operator is finite. In this paper we present some new classes of finite operators containing the class of paranormal operators and we prove that the range of a generalized derivation is orthogonal to its kernel for a large class of operators containing the class of normal operators.

• Journal of Communications and Networks
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• 제13권1호
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• pp.1-5
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• 2011

Feedback with carry shift registers (FCSRs) over 2-adic number would be suitable in hardware implementation, but the are not efficient in software implementation since their basic unit (the size of register clls) is 1-bit. In order to improve the efficiency we consider FCSRs over $2^{\ell}$-adic number (i.e., FCSRs with register cells of size ${\ell}$-bit) that produce ${\ell}$ bits at every clocking where ${\ell}$ will be taken as the size of normal words in modern CPUs (e.g., ${\ell}$ = 32). But, it is difficult to deal with the carry that happens when the size of summation results exceeds that of normal words. We may use long variables (declared with 'unsigned _int64' or 'unsigned long long') or conditional operators (such as 'if' statement) to handle the carry, but both the arithmetic operators over long variables and the conditional operators are not efficient comparing with simple arithmetic operators (such as shifts, maskings, xors, modular additions, etc.) over variables of size ${\ell}$-hit. In this paper, we propose some conditions for FCSRs over $2^{\ell}$-adic number which admit fast software implementations using only simple operators. Moreover, we give two implementation examples for the FCSRs. Our simulation result shows that the proposed methods are twice more efficient than usual methods using conditional operators.

• 한국항만경제학회지
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• 제25권4호
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• pp.281-298
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• 2009

기존의 항만에서 이루어지는 컨테이너크레인 운전자 교육은 표준화된 교육방식 없이 장비 기사간의 도제식 교육으로 이루어짐에 따라 항만의 생산성 저하와 항만 내 안전사고의 문제점에 노출되어 왔다. 본 연구는 컨테이너크레인 운전자에 대한 직무분석을 통하여 체계적으로 운영인력을 육성 관리할 수 있는 방안을 제안하는데 그 목적이 있다. 이를 위하여 기존 컨테이너크레인 교육과정의 문제점을 조사하였고, 이를 바탕으로 데이컴(DACUM) 방법에 따른 직무분석을 실시하여 직무의 모형을 설정하였다. 컨테이너크레인 운전자 직무분석 결과 총 6개의 책무와 각 책무를 구성하는 43개의 작업을 도출하였다. 그리고 현장 맞춤형 교육 과정을 개발하기 위하여 교육 요구도 분석을 하였다. 각 작업에 대해 중요도와 난이도 및 수행 빈도를 조사하고 입직 초기에 갖추어야 할 핵심 작업을 분석하였다. 또한 본 연구에서는 이러한 직무분석 결과를 구조화하고 체계화하여 컨테이너크레인 운전자 직무분야에 대한 직무모형을 제시하였다.