• Honam Mathematical Journal
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• v.44 no.1
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• pp.110-120
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• 2022

In this paper, we introduce the concepts of Wijsman invariant statistical, Wijsman deferred invariant statistical and Wijsman strongly deferred invariant convergence of order 𝜂 (0 < 𝜂 ≤ 1) for set sequences. Also, we investigate some properties of these concepts and some relationships between them.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.5
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• pp.445-451
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• 2022

Ultrasonic sensor is suitable as a next-generation autonomous driving assist device because its lower price compared to that of other sensors and its sensing stability in the external environment. Although Pb(Zr, Ti)O₃ (PZT)-relaxor ferroelectric system has excellent piezoelectric properties, the change in capacitance is large in the daily operating temperature range due to the low phase transition temperature. Recently, many studies have been conducted to improve the temperature stability of ferroelectric ceramics by controlling the grain size and crystal structure, so it is necessary to study the effect of the grain size on the piezoelectric properties and the temperature stability of PZT-relaxor ferroelectric system. In this study, the piezoelectric properties, phase transition temperature, and temperature coefficient of capacitance (TCC) of 0.9 Pb(Zr_1-xTi_x)O₃-0.1 Pb(Zn_1/3Nb_2/3)O₃ (PZT_x-PZN) ceramics with various grain sizes were investigated. PZT_x-PZN ceramics with larger grain size showed higher piezoelectric properties and temperature stability, and are expected to be suitable for ultrasonic devices in the future.

• The Journal of the Korea Contents Association
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• v.3 no.4
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• pp.103-110
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• 2003

In this paper, we investigate the properties of fuzzy spheres and estabilish convergence theorems of them. We expect that convergence theorems of fuzzy spheres may be useful for computer graphics and patten recognition.

• Korean Journal of Mathematics
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• v.19 no.1
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• pp.53-59
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• 2011

We study some properties of integrable semigroup and its generator, and then we establish convergence of integrable semigroups on the norming dual pairs.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.1051-1054
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• 1988

In this paper we present initial convergence properties of the Kalman filtering algorithm, we put an arbitrary small positive correlation matrix as an initial condition in the recursive algorithm. This arbitrary small initial condition perturbs the Kalman filtering algorithm and may lead to initial instability. We derive a condition which insures the stable operation of the Kalman filtering algorithm from the stochastic Lyapunov difference equation.

• Journal of Applied and Pure Mathematics
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• v.5 no.3_4
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• pp.265-279
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• 2023

In this paper, we firstly presented the definitions of arithmetic ${\mathcal{I}}$-statistically convergence, ${\mathcal{I}}$-lacunary arithmetic statistically convergence, strongly ${\mathcal{I}}$-lacunary arithmetic convergence, ${\mathcal{I}}$-Cesàro arithmetic summable and strongly ${\mathcal{I}}$-Cesàro arithmetic summable using weighted density via Orlicz function ${\tilde{\phi}}$. Then, we proved some theorems associated with these concepts, and we examined the relationship between them. Finally, we establish some sequential properties of ${\mathcal{I}}$-lacunary arithmetic statistical continuity.

• Carbon letters
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• v.20
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• pp.39-46
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• 2016

In this work, the effects of maleic anhydride (MA) content on mechanical properties of chopped carbon fibers (CFs)-reinforced MA-grafted-polypropylene (MAPP) matrix composites. A direct oxyfluorination on CF surfaces was applied to increase the interfacial strength between the CFs and MAPP matrix. The mechanical properties of the CFs/MAPP composites are likely to be different in terms of MA content. Surface characteristics were observed by scanning electron microscope, Fourier transform infrared spectroscopy, and single fiber contact angle method. The mechanical properties of the composites were also measured by a critical stress intensity factor (K_IC). From the K_IC test results, the K_IC values were increased to a maximum value of 3.4 MPa with the 0.1 % of MA in the PP, and then decreased with higher MA content.

• Elastomers and Composites
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• v.51 no.3
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• pp.188-194
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• 2016

In this study, novel quaternary plastomers consisting of ethylene, 1-hexene, high ${\alpha}$-olefin, and divinylbenzene were prepared using Zr metallocene catalyst, borate type cocatalyst, and tri-isobutylaluminium. The molar ratio changes of 1-hexene and high ${\alpha}$-olefin (1-octene, 1-decene, and 1-dodecene) had an effect on the properties of the quaternary plastomers. The structure of the quaternary plastomers was characterized using $^1H$ NMR. Molecular weight properties, crystallinity, and thermal properties of the plastomers were determined by GPC, WAXS, and DMA, respectively. Compared with the terpolymers prepared in our previous study, molecular weight and molecular weight distribution of the quaternary polymers were very similar, whereas glass transition temperature ($T_g$) was very low. Also, hardness and tensile properties of the quaternary plastomers were measured.

• Communications of the Korean Mathematical Society
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• v.11 no.4
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• pp.1087-1094
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• 1996

In this paper, we introduce the notion of the n-th pretopological modification. Also, we find some properties which hold between convergence quotient maps and n-th pretopological modifications.

• Communications of the Korean Mathematical Society
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• v.18 no.3
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• pp.533-540
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• 2003

We introduce the notion of semi-convergence of p-stacks and by using that notion we characterize the semi-interior, semiclosure, separation axioms and semi-continuity on a topological space. Also we introduce a new notion of p-somicompactness and investigate its properties in terms of semi-convergence of p-stacks.