• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.234-240
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• 2007

The electrical properties and dc aging behavior for specified stress state of system, which is composed of quaternary Zn-Pr-Co-Cr, were investigated for different $Dy_2O_3$ addition doping level. As $Dy_2O_3$ doping level increased, the density decreased in the range of 5.51-4.90 $g/cm^3$, reaching maximum at 0.5 mol% and the average ZnO grain size decreased in the range of 17.7-6.0 ${\mu}m$. The incorporation of $Dy_2O_3$ significantly improved the non-ohmic properties, above 30 in non-ohmic coefficient, compared with that of undoped samples. The samples with the best performance of non-ohmic properties were obtained for $Dy_2O_3$ doping level of 1.0 mol%, with 49 in non-ohmic coefficient and 2.6 ${\mu}A/cm^2$ in leakage current. The samples with the highest stability were obtained for $Dy_2O_3$ doping level of 0.5 mol%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.955-958
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• 2001

The structure characteristics of varistor of Zn oxide to depend on the breakdown voltage has been investigated to annealing condition by additive material of Sb$_2$O$_3$ system. The breakdown voltage that has not doping Sb$_2$O$_3$ was 235[V]. ZnO varistors was shown ohmic properties when it's applied voltage was below critical voltage. It was shown non-ohmic properties over critical voltage, because current was increased with decreasing resistance. High voltage ZnO varistors had high breakdown voltage, but it had bad electrical stability with various surge. Sb$_2$O$_3$was increased non-linear coefficient in ZnO varistors grain boundary.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.373-376
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• 2001

When varistors for circuit protection is used at high voltage, it's operation properties were unstable because of leakage current and nonlinear coefficient with grain size. For the purpose of improving of ZnO varistor properties, high voltage ZnO varistor was fabricated with Y$_2$O$_3$addition. Electrical properties were investigated according to sintering conditions and mixing conditions. ZnO varistors was shown ohmic Properties when it's applied voltage was below critical voltage. It was shown non-ohmic properties over critical voltage, because current was increased with decreasing resistance.

• Journal of Magnetics
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• v.21 no.1
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• pp.153-158
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• 2016

This paper aims to discuss the Non Darcy boundary layer flow of non-conducting viscous fluid with magnetic ferroparticles over a permeable linearly stretching surface with ohmic dissipation and mixed convective heat transfer. A magnetic dipole is applied "a" distance below the surface of stretching sheet. The governing equations are modeled. Similarity transformation is used to convert the system of partial differential equations to a system of non-linear but ordinary differential equations. The ODEs are solved numerically. The effects of sundry parameters on the flow properties like velocity, pressure, skin-friction coefficient and Nusselt number are presented. It is deduced the frictional resistance of Lorentz force decreases with stronger electric field and the trend reverses for temperature. Skin friction coefficient increase with increase in ferromagnetic interaction parameter. Whereas, Nusselt number decrease.

• Transactions on Electrical and Electronic Materials
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• v.15 no.5
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• pp.284-289
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• 2014

The effects of additives (Nb, Bi and Cr) on the microstructure, varistor properties, and aging behavior of V/Mn/Co/ La/Dy co-doped zinc oxide ceramics were systematically investigated. An analysis of the microstructure showed that all of the ceramics that were modified with various additives were composed of zinc oxide grain as the main phase, and secondary phases such as $Zn_3(VO_4)_2$, $ZnV_2O_4$, and $DyVO_4$. The $Bi_2O_3$-modified samples exhibited the lowest density, the $Nb_2O_5$-modified sample exhibited the largest average grain size, and the $Cr_2O_3$-modified samples exhibited the highest breakdown field. All additives improved the non-ohmic coefficient (${\alpha}$) by either a small or a large margin, and in particular an $Nb_2O_5$ additive noticeably increased the non-ohmic coefficient to be as large as 36. The $Bi_2O_3$-modified samples exhibited the highest stability with variation rates for the breakdown field and for the non-ohmic coefficient (${\alpha}$) of -1.2% and -26.3%, respectively, after application of a DC accelerated aging stress of 0.85 EB/$85^{\circ}C$/24 h.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1697-1701
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• 2016

The leakage conduction and critical voltage characteristic of ZnO ceramic were investigated as a function of $Sb_2O_3$ concentration. Leakage conduction in the ohmic region increased with increasing $Sb_2O_3$ concentration and was attributed to the potential barrier height. The nonlinear coefficient increased with an increasing amount of $Sb_2O_3$. It was found that increases in the apparent critical voltages were associated with the lowered donor concentration in the grain boundary of between two ZnO grains. And the decrease of donor concentration on doping with $Sb_2O_3$ additive was attributed to the lowered capacitance in the grain boundary layer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.14-18
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• 2018

Generally. the Ohmic's law is an important factor to increase the conductivity in a micro device. So it is also known that the Ohmic contact in a semiconductor device is import. The PN junction as a structure of semiconductor involves the depletion layer, and this depletion layer induces the non linear electrical properties and also makes the Schottky contact as an intrinsic characteristics of semiconductor. To research the conduction effect of insulators in the semiconductor device, $SiO_2$ thin film and $V_2O_5/SiO_2$ thin film were researched by using the current-voltage system. In the nano electro-magnetic system, the $SiO_2$ thin film as a insulator had the non linear Schottky contact, and the as deposited $V_2O_5$ thin film had the linear Ohmic contact owing to the $SiO_2$ thin film with superior insulator's properties, which decreases the leakage current. In the positive voltage, the capacitance of $SiO_2$ thin film was very low, but that of $V_2O_5$ thin film increased with increasing the voltage. In the normal electric field system, it was confirmed that the conductivity of $V_2O_5$ thin film was increased by the effect of $SiO_2$ thin film. It was confirmed that the Schottky contact of semiconductors enhanced the performance of electrical properties to increased the conductivity.

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.1
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• pp.48-55
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• 2024

The electrochemically active site of mixed ionic and electronic conductor (MIEC) as a cathode material is restricted to the triple phase boundary in protonic ceramic fuel cells (PCFCs) due to the insufficient of proton-conducting properties of MIEC. This study primarily focused on expanding the electrochemically active site by La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ(LSCF6428)-BaZr_0.4Ce_0.4Y_0.1Yb_0.1O_3-δ (BZCYYb4411) composite cathode. The electrochemical properties of the composite cathode were evaluated using anode-supported PCFC single cells. In comparison to the LSCF6428 cathode, the peak power density of the LSCF6428-BZCYYb4411 composite cathode is much enhanced by the reduction in both ohmic and non-ohmic resistance, possibly due to the increased electrochemically active site.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.502-508
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• 2020

This paper focuses on the electrical properties and stability against DC accelerated aging stress of ZnO-V₂O₅-MnO₂-Nb₂O₅-Bi₂O₃-Co₃O₄-Dy₂O₃ (ZVMNBCD) varistor ceramics sintered at 850 - 925 ℃. With the increase of sintering temperature, the average grain size increases from 4.4 to 11.8 mm, and the density of the sintered pellets decreases from 5.53 to 5.40 g/㎤ due to the volatility of V₂O₅, which has a low melting point. The breakdown field abruptly decreases from 8016 to 1,715 V/cm with the increase of the sintering temperature. The maximum non-ohmic coefficient (59) is obtained when the sample is sintered at 875 ℃. The samples sintered at below 900 ℃ exhibit a relatively low leakage current, less than 60 mA/㎠. The apparent dielectric constant increases due to the increase of the average grain size with the increase of the sintering temperature. The change tendency of dissipation factor at 1 kHz according to the sintering temperature coincides with the tendency of the leakage current. In terms of stability, the samples sintered at 900 ℃ exhibit both high non-ohmic coefficient (45) and excellent stability, 0.8% in 𝚫E_B/E_B and -0.7 % in 𝚫α/α after application of DC accelerated aging stress (0.85 E_B/85 ℃/24 h).

• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.66-69
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• 2018

This study was researched the electrical properties of semiconductor devices such as ITO, $SiO_2$, $V_2O_5$ thin films. The films of ITO, $SiO_2$, $V_2O_5$ were deposited by the rf magnetron sputtering system with mixed gases of oxygen and argon to generate the plasma. All samples were cleaned before deposition and prepared the metal electrodes to research the current-voltage properties. The electrical characteristics of semiconductors depends on the interface's properties at the junction. There are two kinds of junctions such as ohmic and schottky contacts in the semiconductors. In this study, the ITO thin film was shown the ohmic contact properties as the linear current-voltage curves, and the electrical characteristics of $SiO_2$ and $V_2O_5$ films were shown the non-linear current-voltage curves as the schottky contacts. It was confirmed that the electronic system with schottky contacts enhanced the electronic flow owing to the increment of efficiency and increased the conductivity. The schottky contact was only defined special characteristics at the semiconductor and the interface depletion layer at the junction made the schottky contact which has the effect of leakage current cutoff. Consequently the semiconductor device with shottky contact increased the electronic current flow, in spite of depletion of carriers.