• Journal of the Korean Mathematical Society
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• v.32 no.3
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• pp.493-507
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• 1995

The Hartman-Stampacchia variational inequality was first suggested and studied by Hartman and Stampacchia [8] in finite dimensional spaces during the time establishing the base of variational inequality theory in 1960s [4]. Then it was generalized by Lions et al. [6], [9], [10], Browder [3] and others to the case of infinite dimensional inequality [3], [9], [10], and the results concerning this variational inequality have been applied to many important problems, i.e., mechanics, control theory, game theory, differential equations, optimizations, mathematical economics [1], [2], [6], [9], [10]. Recently, the Browder-Hartman-Stampaccnia variational inequality was extended to the case of set-valued monotone mappings in reflexive Banach sapces by Shih-Tan [11] and Chang [5], and under different conditions, they proved some existence theorems of solutions of this variational inequality.

• Kyungpook Mathematical Journal
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• v.49 no.4
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• pp.605-618
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• 2009

A stage-structured predator-prey system with time delay and Beddington-DeAngelis functional response is considered. By analyzing the corresponding characteristic equation, the local stability of a positive equilibrium is investigated. The existence of Hopf bifurcations is established. Formulae are derived to determine the direction of bifurcations and the stability of bifurcating periodic solutions by using the normal form theory and center manifold theorem. Numerical simulations are carried out to illustrate the theoretical results.

• Bulletin of the Korean Mathematical Society
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• v.59 no.6
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• pp.1439-1470
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• 2022

In this paper, we study the uniform attractor of the 2D nonautonomous tropical climate model in an arbitrary unbounded domain on which the Poincaré inequality holds. We prove that the uniform attractor is compact not only in the L²-spaces but also in the H¹-spaces. Our proof is based on the concept of asymptotical compactness. Finally, for the quasiperiodical external force case, the dimension estimates of such a uniform attractor are also obtained.

• Honam Mathematical Journal
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• v.44 no.2
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• pp.165-178
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• 2022

In this paper, Sheffer stroke BL-algebra and its properties are investigated. It is shown that a Cartesian product of two Sheffer stroke BL-algebras is a Sheffer stroke BL-algebra. After describing a filter of Sheffer stroke BL-algebra, a congruence relation on a Sheffer stroke BL-algebra is defined via its filter, and quotient of a Sheffer stroke BL-algebra is constructed via a congruence relation. Also, it is defined a homomorphism between Sheffer stroke BL-algebras and is presented its properties. Thus, it is stated that the class of Sheffer stroke BL-algebras forms a variety.

• Honam Mathematical Journal
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• v.44 no.1
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• pp.78-97
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• 2022

In this study, new properties of various filters on a Sheffer stroke BL-algebra are studied. Then some new results in filters of Sheffer stroke BL-algebras are given. Also, stabilizers of nonempty subsets of Sheffer stroke BL-algebras are defined and some properties are examined. Moreover, it is shown that the stabilizer of a filter with respect to a/n (ultra) filter of a Sheffer stroke BL-algebra is its (ultra) filter. It is proved that the stabilizer of the subset {0} of a Sheffer stroke BL-algebra is {1}. Finally, it is stated that the stabilizer St(P, Q) of P with respect to Q is an ultra filter of a Sheffer stroke BL-algebra when P is any filter and Q is an ultra filter of this algebra.

• Korean Journal of Mathematics
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• v.31 no.1
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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.

• Journal of Korean Home Economics Education Association
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• v.17 no.1 s.35
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• pp.55-68
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• 2005

The purpose of this study was to compare the content of 'Management of Resource and Environment' area in middle school Home Economics textbook with other middle school subject textbooks. The middle school textbooks of Korean. Mathematics. Social Science. Science. Ethics. Technology. Arts. Music, and Physical Education were analyzed how the contents of these textbooks were similar to or different from those of 'Management of Resource and Environment' area in Home Economics textbooks. The contents of 8 subject textbooks except Music were related with those of 'Management of Resource and Environment' area in Home Economics textbooks. The content of Social Science was the most similar to 'Management of Resource and Environment' area in Home Economics textbooks although perspectives and focus were somewhat different. The unit of Home Economics textbook most related with contents of other subject textbooks was' Our Consumption Lives'. while 'Management of Time and Work for Adolescence' is the unit of Home Economics textbook least related with contents of other subject textbooks. However. similar contents were dealt with different focus and depth in textbooks according to objectives and characteristics of subject.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.6
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• pp.185-195
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• 2020

The study investigates the impact of globalization on coal consumption in Vietnam. This study employs an autoregressed distributed lag approach on time series data for the period of 1990 to 2017. The study tests the stationary, cointegration of time series data and utilizes autoregressed distributed lag modeling technique to determine the short-run and long-run relationship among coal consumption, globalization, income, population, and CO₂ emissions. The results show that globalization increases coal consumption in Vietnam in the long run. The results also show that rapid economic growth promotes more coal consumption in the short run as well as in the long run. Moreover, higher population reduces coal consumption, and CO₂ emissions decrease coal consumption both in the short run and the long run. The findings of the study suggest that globalization increases coal consumption in Vietnam in the long run. This result suggests that the increase in globalization level in Vietnam increases coal consumption. An interesting finding is that higher population reduces coal consumption, and population is an important factor towards the lessening in coal consumption. The findings confirm that environmental pollution decreases coal consumption in the short run and the long run. This implies that coal consumption may be green consumption in Vietnam.

• International Journal of Computer Science & Network Security
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• v.22 no.2
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• pp.406-412
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• 2022

Storing large amounts of data has always been a big problem from the beginning of computing history. Big Data has made huge advancements in improving business processes by finding the customers' needs using prediction models based on web and social media search. The main purpose of big data stream processing frameworks is to allow programmers to directly query the continuous stream without dealing with the lower-level mechanisms. In other words, programmers write the code to process streams using these runtime libraries (also called Stream Processing Engines). This is achieved by taking large volumes of data and analyzing them using Big Data frameworks. Streaming platforms are an emerging technology that deals with continuous streams of data. There are several streaming platforms of Big Data freely available on the Internet. However, selecting the most appropriate one is not easy for programmers. In this paper, we present a detailed description of two of the state-of-the-art and most popular streaming frameworks: Apache Ignite and Hazelcast. In addition, the performance of these frameworks is compared using selected attributes. Different types of databases are used in common to store the data. To process the data in real-time continuously, data streaming technologies are developed. With the development of today's large-scale distributed applications handling tons of data, these databases are not viable. Consequently, Big Data is introduced to store, process, and analyze data at a fast speed and also to deal with big users and data growth day by day.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.9
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• pp.273-285
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• 2021

This study estimates the financial value of return on investment (ROI) of research funds. Four simulation estimations are employed to measure ROI finance value that considers the outputs, outcomes, impacts and total ROI from the allocation input received. Research outputs, outcomes, and impacts can be quantitatively measured based on improvements to existing systems. In terms of input, the Malaysian government has allocated MYR301,350,000 for fundamental research in the 2021 budget compared with 2019, up 9.5 percent from 2019. It brings up the question: To what extent does the input of research funds allocated by the government yield a good return in outputs, outcomes, and impacts to the academic community, society, and country? The result of total ROI shows around MYR7 return is generated by researchers for each Malaysian ringgit channeled by the funder. More specifically, for a research project, it is more difficult to produce impacts and outcomes compared to research outputs. The positive return is evidence that all the allocated funds are beneficial to the stakeholders. The government can apply this approach in calculating ROI for evaluation and fund allocation to universities. Furthermore, the positive financial value of research output, outcome, and impact automatically contribute to a positive innovation environment in Malaysia.