• 대한수학회보
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• 제49권6호
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• pp.1199-1211
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• 2012

In this paper we give an introduction to the theory of universal central extensions of perfect Lie algebras. In particular, we will provide a model for the universal coverings of Lie tori and we show that automorphisms and derivations lift to the universal coverings. We also prove that the universal covering of a Lie ${\Lambda}$-torus of type ${\Delta}$ is again a Lie ${\Lambda}$-torus of type ${\Delta}$.

• 대한수학회보
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• 제51권1호
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• pp.115-128
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• 2014

In this paper, we study the second approximate Matsumoto metric F = ${\alpha}+{\beta}+{\beta}^2/{\alpha}+{\beta}^3/{\alpha}^2$ on a manifold M. We prove that F is of scalar flag curvature and isotropic S-curvature if and only if it is isotropic Berwald metric with almost isotropic flag curvature.

• 대한수학회논문집
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• 제37권3호
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• pp.801-812
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• 2022

In this paper, we introduce the multi-derivations on rings and present some examples of such derivations. Then, we unify the system of functional equations defining a multi-derivation to a single formula. Applying a fixed point theorem, we will establish the generalized Hyers-Ulam stability of multi-derivations in Banach module whose upper bounds are controlled by a general function. Moreover, we give some important applications of this result to obtain the known stability outcomes.

• Parasites, Hosts and Diseases
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• 제54권1호
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• pp.61-66
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• 2016

It has been known that Arak, Salvadora persica, has a number of medicinal properties. We tried to investigate in vitro scolicidal effect of root extracts of this plant against protoscolices from hydatid cysts of Echinococcus granulosus. Protoscolices were aseptically collected from sheep livers containing hydatid cysts. S. persica root extract was used in 10, 30, and 50 mg/ml concentration for 10, 20, and 30 min. The viability of protoscolices was ascertained by 0.1% eosin staining. Scolicidal activity of S. persica extract at a concentration of 10 mg/ml was 36.3%, 50.3%, and 70.8% after 10, 20, and 30 min of exposure, respectively. The scolicidal effect of this extract at a concentration of 30 mg/ml was 52.9%, 86.7%, and 100% after 10, 20, and 30 min of exposure, respectively. S. persica extract at a concentration of 50 mg/ml, meanwhile, killed 81.4%, 100%, and 100% of protoscolices after 10, 20, and 30 min, respectively. Also, the cytotoxic potential of S. persica was assessed on human liver cells (HepG2) using trypan blue exclusion test. No cytotoxic effect was observed on HepG2 cell line. The present study confirmed for the first time that the ethanolic extract of S. persica has high scolicidal power in vitro. However, in vivo effect of this material remains to be studied for treatment of echinococcosis in humans and herbivorous animals.

• Clinical and Experimental Pediatrics
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• 제64권11호
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• pp.575-581
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• 2021

Background: Toxocariasis is a zoonotic parasitic disease caused by Toxocara canis and Toxocara cati in humans. Various types of T. canis are important. Purpose: The current study aimed to investigate the prevalence of Toxocara spp. in pediatrics in the context of a systematic review and meta-analysis. Methods: The MEDLINE (PubMed), Web of Sciences, Embase, Google Scholar, Scopus, and Cumulative Index of Nursing and Allied Health databases were searched to identify peer-reviewed studies published between January 2000 and December 2019 that report the prevalence of Toxocara spp. in pediatrics. The evaluation of articles based on the inclusion and exclusion criteria was performed by 2 researchers individually. Results: The results of 31 relevant studies indicated that the prevalence of Toxocara spp. was 3%-79% in 10,676 cases. The pooled estimate of global prevalence of Toxocara spp. in pediatrics was 30 (95% confidence interval, 22%-37%; I²=99.11%; P=0.00). The prevalence was higher in Asian populations than in European, American, and African populations. Conclusion: Health policymakers should be more attentive to future research and approaches to Toxocara spp. and other zoonotic diseases to improve culture and identify socioeconomically important factors.

• Geomechanics and Engineering
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• 제36권2호
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• pp.111-119
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• 2024

In the realm of rock excavation projects, precise estimation of the drilling rate index stands as a pivotal factor in strategic planning and cost assessment. This study introduces and evaluates two pioneering computational intelligence models designed for the prognostication of the drilling rate index, a pivotal parameter with direct implications for cost estimation in rock excavation projects. These models, denoted as the Relevance Vector Regression (RVR) optimized with the Invasive Weed Optimization algorithm (IWO) (RVR-IWO model) and the RVR integrated with the Shuffled Frog Leaping algorithm (SFL) (RVR-SFL model), represent a groundbreaking approach to forecasting drilling rate index. The RVR-IWO and RVR-SFL models were meticulously devised to harness the capabilities of computational intelligence and optimization techniques for drilling rate index estimation. This research pioneers the integration of IWO and SFL with RVR, constituting an unprecedented effort in forecasting drilling rate index. The primary objective of this study was to gauge the precision and dependability of these models in forecasting the drilling rate index, revealing significant distinctions between the two. In terms of predictive precision, the RVR-IWO model emerged as the superior choice when compared to the RVR-SFL model, underscoring the remarkable efficacy of the Invasive Weed Optimization algorithm. The RVR-IWO model delivered noteworthy results, boasting a Variance Account for (VAF) of 0.8406, a Mean Squared Error (MSE) of 0.0114, and a Squared Correlation Coefficient (R²) of 0.9315. On the contrary, the RVR-SFL model exhibited slightly lower precision, yielding an MSE of 0.0160, a VAF of 0.8205, and an R2 of 0.9120. These findings serve to highlight the potential of the RVR-IWO model as a formidable instrument for drilling rate index prediction, particularly within the framework of rock excavation projects. This research not only makes a significant contribution to the realm of drilling engineering but also underscores the broader adaptability of the RVR-IWO model in tackling an array of challenges within the domain of rock engineering. Ultimately, this study advances the comprehension of drilling rate index estimation and imparts valuable insights into the practical implementation of computational intelligence methodologies within the realm of engineering projects.

• Structural Engineering and Mechanics
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• 제90권3호
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• pp.219-232
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• 2024

In current study, for the first time, Nonlinear Bending of a skew microplate made of a laminated composite strengthened with graphene nanosheets is investigated. A mixture of mechanical and thermal stresses is applied to the plate, and the reaction is analyzed using the First Shear Deformation Theory (FSDT). Since different percentages of graphene sheets are included in the multilayer structure of the composite, the characteristics of the composite are functionally graded throughout its thickness. Halpin-Tsai models are used to characterize mechanical qualities, whereas Schapery models are used to characterize thermal properties. The microplate's non-linear strain is first calculated by calculating the plate shear deformation and using the Green-Lagrange tensor and von Karman assumptions. Then the elements of the Couple and Cauchy stress tensors using the Modified Coupled Stress Theory (MCST) are derived. Next, using the Hamilton Principle, the microplate's governing equations and associated boundary conditions are calculated. The nonlinear differential equations are linearized by utilizing auxiliary variables in the nonlinear solution by applying the Frechet approach. The linearized equations are rectified via an iterative loop to precisely solve the problem. For this, the Differential Quadrature Method (DQM) is utilized, and the outcomes are shown for the basic support boundary condition. To ascertain the maximum values of microplate deflection for a range of circumstances-such as skew angles, volume fractions, configurations, temperatures, and length scales-a parametric analysis is carried out. To shed light on how the microplate behaves in these various circumstances, the resulting results are analyzed.

• Structural Monitoring and Maintenance
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• 제5권3호
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• pp.345-361
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• 2018

The set of processes performed to determine the dynamic characteristics of the constructed structures is named experimental modal analysis. Using experimental modal analysis and interpreting its results, structural failure can be assessed and then it would be possible to plan for their repair and maintenance. The purpose of the experimental modal analysis is to determine the resonance frequencies, mode shapes and Mode damping for the structure. Diverse methods for determining the shape of the mode by various researchers have been presented. There are pros and cons for each of these methods. This paper presents a method for determining the mode shape of the structures using the response spectrum in the experimental modal analysis. In the first part, the principles of the proposed method are described. Then, to check the accuracy of the results obtained from the proposed method, single and multiple degrees of freedom models were numerically and experimentally investigated.

• Membrane and Water Treatment
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• 제7권2호
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• pp.87-100
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• 2016

A numerical simulation of membrane evaporation process was carried out in this work. The aim of simulation is to describe transport of water through porous membranes applicable to the concentration of aqueous solutions. A three-dimensional mathematical model was developed which considers transport phenomena including mass, heat, and momentum transfer in membrane evaporation process. The equations of model were then solved numerically using finite element method. The results of simulation in terms of evaporation flux were compared with experimental data, and confirmed the accuracy of model. Moreover, profile of pressure, concentration, and heat flux were obtained and analyzed. The results revealed that developed 3D model is capable of predicting performance of membrane evaporators in concentration of aqueous solutions.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2943-2948
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• 2009

Copper-dimethylglyoxime complex (CuDMG) modified Copper electrode (Cu/CuDMG) showed a catalytic activity towards cyclohexanol oxidation in NaOH solution. The modified electrode prepared by the dimethylglyoxime anodic deposition on Cu electrode in the solution contained 0.20 M $NH_4Cl\;+\;NH_4OH\;(pH\;9.50)\;and\;1\;{\times}\;10^{-4}$ M dimethylglyoxime. The modified electrode conditioned by potential recycling in a potential range of -900${\sim}$900 mV vs. Ag/AgCl by cyclic voltammetry in alkaline medium (1 M NaOH). The results show that the CuDMG film on the electrode behaves as an efficient catalyst for the electro-oxidation of cyclohexanol in alkaline medium via Cu (III) species formed on the electrode.