• Advances in nano research
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• v.16 no.4
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• pp.341-352
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• 2024

This study investigates the heat and mass transfer characteristics of a MoS₂ nanoparticle suspension in ethylene glycol over a porous stretching sheet. MoS₂ nanoparticles are known for their exceptional thermal and chemical stability which makes it convenient for enhancing the energy and mass transport properties of base fluids. Ethylene glycol, a common coolant in various industrial applications is utilized as the suspending medium due to its superior heat transfer properties. The effects of variable thermal conductivity, variable mass diffusivity, thermal radiation and thermophoresis which are crucial parameters in affecting the transport phenomena of nanofluids are taken into consideration. The governing partial differential equations representing the conservation of momentum, energy, and concentration are reduced to a set of nonlinear ordinary differential equations using appropriate similarity transformations. R software and MATLAB-bvp5c are used to compute the solutions. The impact of key parameters, including the nanoparticle volume fraction, magnetic field, Prandtl number, and thermophoresis parameter on the flow, heat and mass transfer rates is systematically examined. The study reveals that the presence of MoS₂ nanoparticles curbs the friction between the fluid and the solid boundary. Moreover, the variable thermal conductivity controls the rate of heat transfer and variable mass diffusivity regulates the rate of mass transfer. The numerical and statistical results computed are mutually justified via tables. The results obtained from this investigation provide valuable insights into the design and optimization of systems involving nanofluid-based heat and mass transfer processes, such as solar collectors, chemical reactors, and heat exchangers. Furthermore, the findings contribute to a deeper understanding of stretching sheet systems, such as in manufacturing processes involving continuous casting or polymer film production. The incorporation of MoS₂-C₂H₆O₂ nanofluids can potentially optimize temperature distribution and fluid dynamics.

• Korean Journal of Veterinary Research
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• v.24 no.1
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• pp.91-98
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• 1984

A total of 466 foremilk from dairy farms in Chonnam district was examined for the subclinical mastitis over a period of one year, using a method of the electrical conductivities(EC); absolute conductivity(AC) and differential conductivity(DC) and quarter difference value(QD), in relation to the California mastitis test(CMT) and the direct somatic cell count(DSCC). The compatibility and efficiency rating between the EC values and the other screening tests was conducted. Obtained results are summarized as follows. 1. A linear relationship was found between the EC values and the CMT scores and direct somatic cell counts and it was found that electrical conductivity measurements were comparable with other screening tests for diagnosing animals with mastitis. 2. Compatibilities between the EC and CMT were 70.4% in AC, 74.6% in DC and 70.7% in QD, and that of the EC and DSCC were 53.0% in AC, 63.1% in DC and 53.2% in QD. On the other hand, relative efficiency ratings of Postle's equation between EC and CMT were 37.3% in AC, 26.5% in DC and 13.6% in QD, and that of the EC and DSCC were 33.1% in AC, 20.2% in DC and 11.9% in QD. 3. In the foremilk samples collected from damaged quarters determined by EC, the false positive rate wart higher than the false negative rate, and consequently tests of EC produced lower compatibility or efficiency rating scores. These tendencies suggested that any factors other than the mastitic condition influencing the EC values might be existed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.304-304
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• 2006

Ternary tellurite glassy systems ($Li_2O-V_2O_5-TeO_2$) have been synthesised using Vanadium oxide as a network former and Lithium oxide as network modifier. The addition of a metal oxide makes them electric or mixed electric-ionic conductors, which are of potential interest as cathode materials for solid-state batteries. This glass-ceramics crystallized from the $Li_2O-V_2O_5-TeO_2$ system are particularly interesting, because they exhibit high conductivity (up to $5.63{\times}10^{-5}$ S/cm) at room temperature the glass samples were prepared by quenching the melt on the copper plate and the glass-ceramics were heat-treated at crystallizing temperature determined from differential thermal analysis (DTA). The electric DC conductivity result have been analyzed in terms of a small polaron-hopping model.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.2
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• pp.131-138
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• 2014

Highly conductive bipolar plate for polymer electrolyte membrane fuel cell (PEMFC) was prepared using phenol novolac-type epoxy/graphite powder (GP)/carbon fiber filament (CFF) composite, and a rubber-modified epoxy resin was introduced in order to give elasticity to the bipolar plate graphite fiber (GF) was incorporated in order to improve electrical conductivity. To find out the cure condition of the mixture of novolac-type and rubber-modified epoxies, differential scanning calorimetry (DSC) was carried out and their data were introduced to Kissinger equation. And tensile and flexural tests were carried out using universal testing machine (UTM) and the surface morphology of the fractured specimen and the interfacial bonding between epoxy matrix and CFF or GF were observed by a scanning electron microscopy (SEM).

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.254-259
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• 2013

The mechanisms of resistance to oxyfluorfen (OF) and paraquat (PQ) were investigated in rice plants. Examination of the concentration dependence of oxyfluorfen- or paraquat-induced increase in conductivity showed that conductivities in the OF- and PQ-treated leaf squares were increased with 0.1 ${\mu}M$ oxyfluorfen and 0.01 ${\mu}M$ paraquat and further increased with higher concentrations. The levels of conductivity were approximately 10-times higher in the PQ-treated plants than in the OF-treated plants, indicating that the PQ-treated plants suffered more severe photodynamic damage than the OF-treated plants. The photooxidative stress caused by foliar application of either 50 ${\mu}M$ oxyfluorfen or 100 ${\mu}M$ paraquat increased the enzyme activities of ascorbate peroxidase and peroxidase 1 day after the herbicide treatments and then further increased their enzyme activities 2 days after the treatments. The activities of catalase began to increase 2 days after the oxyfluorfen and paraquat treatments. These antioxidant enzymes appear to play an essential part of defense mechanisms against oxyfluorfen and paraquat. Our results demonstrate that paraquat caused more severe oxidative stress, as indicated by a greater change in conductivity, thereby resulting in greater increases in antioxidant responses in plants, compared with those of oxyfluorfen.

• Macromolecular Research
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• v.16 no.5
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• pp.457-466
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• 2008

The relation between the phase separated morphologies and their transport properties in the polymer blend membrane for direct methanol fuel cell application was studied. In order to enhance the proton conductivity and reduce the methanol crossover, sulfonated poly(arylene ether sulfone) copolymer, with a sulfonation of 60 mol% (sPAES-60), was blended with nonsulfonated poly(ether sulfone) copolymer (RH-2000, Solvay). Various morphologies were obtained by varying the drying condition and the concentration of the casting solution (10, 15, 20 wt%). The transport properties of proton and methanol molecule through the polymer blend membranes were studied according to the absorbed water. AC impedance spectroscopy was used to measure the proton conductivity and a liquid permeability measuring instrument was designed to measure the methanol permeability. The state of water in the blend membranes was confirmed by differential scanning calorimetry and was used to correlate the morphology of the membrane with the membrane transport properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.334-335
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• 2005

Ternary tellurite glassy systems ($Li_2O-V_2O_5-P_2O_5$) have been synthesised using Vanadium oxide as a network former and Lithium oxide as network modifier. The addition of a metal? oxide makes them electric or mixed electric-ionic conductors, which are of potential interest as cathode' materials for solid-state batteries. This glass-ceramics crystallized from the $Li_2O-V_2O_5-P_2O_5$ system are particularly interesting, because they exhibit high conductivity (up to $5.95\times10^{-4}$ S/cm) at room temperature. the glass samples were prepared by quenching the melt on the copper plate and the glass-ceramics were heat-treated at crystallizing temperature determined from differential thermal analysis (DTA). The electric D.C conductivity result have been analyzed in terms of a small polaron-hopping model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.842-844
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• 2004

Ternary tellurite glassy systems $(CuO-V_2O_5-TeO_2)$ have been synthesised using tellurium oxide as a network former and copper oxide as network modifier. The addition of a transition-matal oxide makes them electric or mixed electric-ionic conductors, which are of potential interest as cathode materials for solid-state batteries. This glass-ceramics crystallized from the $CuO-V_2O_5-TeO_2$ system are particularly interesting, because they exhibit high conductivity ( up to $6.03{\times}10^{-3}S/cm$) at room temperature. the glass samples were prepared by quenching the melt on the copper plate and the glass-ceramics were heat-treated at crystallizing temperature determined from differential thermal analysis (DTA). The electric D.C conductivity result have been analyzed in terms of a small polaron-hopping model.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.6
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• pp.962-971
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• 2004

This paper has dealt with thermo-physical properties of microencapsulated phase change material slurry as a latent heat storage material having a low melting point. The measured results of the thermo-physical properties of the test microencapsulated phase change material slurry, those are, density, specific heat, thermal conductivity and viscosity, were discussed for the temperature region of solid and liquid phases of the dispersion material (paraffin). The measurements of these properties of microencapsulated phase change material slurry have been carried out by using a specific-gravity meter, a water calorimeter, a differential scanning calorimeter(DSC), a transient hot wire method and rotating type viscometer, respectively. It was clarified that the additional properties law could be applied to the estimation of the density and specific heat of microencapsulated phase change material slurry and also the Euckens equation could be applied to the estimation of the thermal conductivity of this slurry.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.87-94
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• 1998

After we made the computer source code with mathematical model of Muramatsu et al. that was expressed by the set of simultaneous first-order ordinary differential equations in evaporation-pyrolysis zone of cigarette, we simulated the distribution profiles of temperature and density of flue-cured tobacco. Those equations were solved numerically with the Runge-Kutta-Gill algorithm assuming step size of 0.025mm by Muramatsu at at,, but in this study the advanced algorithm of Runge-Kutta 4th Order assuming step size of 0.0005mm. The initial conditions and physical parameters of Muramatsu et at. were used for solving them. The calculated values corresponded well with results of Muramatsu et al., especially the gradient of the temperature profile increased with smoldering speed and the thickness of the evaporation-pyrolysis zone decreased with increasing of smoldering speed. On the other hand, the temperature gradient decreased with increasing of the effective thermal-conductivity value and the thickness of the evaporation-pyrolysis zone increased with the effective thermal-conductivity value.