• The Pure and Applied Mathematics
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• v.6 no.2
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• pp.67-77
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• 1999

In this paper we study periodic orbit of some planar control systems and investigate phase portraits of the FSs.

• The Pure and Applied Mathematics
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• v.13 no.3 s.33
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• pp.207-215
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• 2006

Using more precise majorizing sequences than before [6], [10], [11], [14] we provide a finer semilocal convergence analysis for a certain class of Euler-Halley type methods for approximating a solution of an equation in a Banach space setting.

• The Pure and Applied Mathematics
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• v.17 no.4
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• pp.333-340
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• 2010

We estimate the real rank of a composition series of closed ideals of a $C^*$-algebra such that its subquotients have continuous trace, which is equivalent to that the $C^*$-algebra is of type I.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.198.2-198.2
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• 2008

• Communications of the Korean Mathematical Society
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• v.34 no.3
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• pp.863-879
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• 2019

In this paper we study the Myers' theorem for orientable Riemannian hypersurfaces under some restrictions on the mean curvature, the second-order mean curvature, or the divergence of the shape operator and give some estimates for the diameter of such hypersurfaces.

• Journal of Applied and Pure Mathematics
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• v.5 no.5_6
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• pp.315-346
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• 2023

We present a variety of univariate and multivariate left and right side Hardy type fractional inequalities, many of them under convexity, and other also of L_p type, p ≥ 1, in the setting of generalized Hilfer and Prabhakar fractional Calculi.

• Journal of Korean Library and Information Science Society
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• v.35 no.4
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• pp.171-191
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• 2004

This study presents revision scheme of Korean Decimal Classification appropriate for classification of children-related materials, mainly centered on social science(300) and pure science(400) occupying the majority of children-related materials in school Libraries. Towards this goal, 1 have studied the development and use of classification system for children-related materials available in domestic and overseas school libraries or children's libraries, and researched elementary school 4th, 5th, and 6th grade students' degree of understanding on classification item terms and children-related materials terms used for KDC's social science and Pure science. Based on the results of analysis, f have presented revision scheme of Korean Decimal Classification item terms and class numbers for children-related materials.

• Advances in materials Research
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• v.3 no.2
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• pp.105-116
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• 2014

The microwave dielectric properties of $CeO_2$ nanoparticles (0.5, 1.0 & 1.5wt%) doped $Mg_2TiO_4$ (MTO) ceramics have been investigated at cryogenic temperatures. The XRD patterns of the samples were refined using the full proof program reveal the inverse spinel structure without any secondary phases. The addition of $CeO_2$ nanoparticles lowered the sintering temperature with enhancement in density and grain size as compared to pure MTO ceramics. This is attributed to the higher sintering velocity of the fine particles. Further, the microwave dielectric properties of the MTO ceramics were measured at cryogenic temperatures in the temperature range of 6.5-295 K. It is observed that the loss tangent ($tan{\delta}$) of all the samples increased with temperature. However, the $CeO_2$ nanoparticles doped MTO ceramics manifested lower loss tangents as compared to the pure MTO ceramics. The loss tangents of the pure and MTO ceramics doped with 1.5 wt% of $CeO_2$ nanoparticles measured at 6.5K are found to be $6.6{\times}10^{-5}$ and $5.4{\times}10^{-5}$, respectively. The addition of $CeO_2$ nanoparticles did not cause any changes on the temperature stability of the MTO ceramics at cryogenic temperatures. On the other hand, the temperature coefficient of the permittivity increased with rise in temperature and with the wt% of $CeO_2$ nanoparticles. The obtained lower loss tangent values at cryogenic temperatures can be attributed to the decrease in both intrinsic and extrinsic losses in the MTO ceramics.

• Human Ecology Research
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• v.52 no.2
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• pp.175-188
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• 2014

This study examined the effects of demographic variables and psychological mechanisms (self-efficacy, need for closure, and fashion innovativeness) on each of the four types of impulsive buying, including suggestion impulsive buying, stimulus impulsive buying, pure impulsive buying, and reminder impulsive buying. In addition, the study analyzed the impact these four types had on evaluations after impulsive buying (i.e., diversion in mood, regret for buying decision and a sense of financial loss, and dissatisfaction of products). Data was collected by a marketing research company from five hundreds consumers in seven different cities of South Korea who experienced impulsive buying in the off-line apparel stores within the past three months. The results of regression analyses indicated that self-efficacy and gender significantly affected suggestion impulsive buying. That is, the higher consumers' self-efficacy, the greater their suggestion impulsive buying was. In addition, women had higher Suggestion Impulsive Buying than men did. However, in case of Stimulus Impulsive Buying, gender was the only significant antecedent. That is, women had higher stimulus impulsive buying than men did. In terms of pure impulsive buying, fashion innovativeness was a significant predictor, and for the reminder impulsive buying level, fashion innovativeness and need for closure were significant predictors. Finally, pure and suggestion impulsive buying were correlated with positive consumer evaluations, while both stimulus and reminder impulsive buyings were correlated with negative consumer evaluations. Implications and future studies were discussed.

• Advances in nano research
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• v.15 no.4
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• pp.295-304
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• 2023

In this paper, a powerful photocatalyst based on carbon nanocomposite is developed in order to obtain a new material applicable in water treatment and especially for the discoloration of effluents used in the textile industry. For that, TiO₂-graphene nanocomposites have been successfully synthesized by a mixture of Functionalized Graphene Sheet (FGS) and tetrachlorotitanium complexes to form FGS-TiO₂ nanocomposite. In the presence of an anionic surfactant, we used a new chemical process to functionalize graphene sheets in order to make them an excellent medium for blocking and preventing the aggregation of TiO₂ nanoparticles. The components of these nanocomposites are characterized by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), which confirms the successful formation of the FGS-TiO₂ nanocomposite. It was found that the TiO₂ nanoparticles were dispersed uniformly on the graphene plane which possesses better charge separation capability than pure TiO₂. The FGS-TiO₂ nanocomposites exhibited higher photocatalytic activity compared to pure TiO₂ for the removal of three dyes: such as Methylene Blue (MB), Bromophenol Blue (BB) and Alizarin Red-S (AR) in water. The removal process was fast and more efficient with FGS-TiO₂ nanocomposite in daylight (in the absence of UV irradiation) compared to pure TiO₂ nanoparticles without and under UV in all pH range.