• Korean Journal of Materials Research
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• v.25 no.8
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• pp.365-369
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• 2015

This paper investigates the dependency of the critical content for electrical conductivity of carbon powder-filled polymer matrix composites with different matrixes as a function of the carbon powder content (volume fraction) to find the break point of the relationships between the carbon powder content and the electrical conductivity. The electrical conductivity jumps by as much as ten orders of magnitude at the break point. The critical carbon powder content corresponding to the break point in electrical conductivity varies according to the matrix species and tends to increase with an increase in the surface tension of the matrix. In order to explain the dependency of the critical carbon content on the matrix species, a simple equation (${V_c}^*=[1+ 3({{\gamma}_c}^{1/2}-{{\gamma}_m}^{1/2})^2/({\Delta}q_cR]^{-1}$) was derived under some assumptions, the most important of which was that when the interfacial excess energy introduced by particles of carbon powder into the matrix reaches a universal value (${\Delta}q_c$), the particles of carbon powder begin to coagulate so as to avoid any further increase in the energy and to form networks that facilitate electrical conduction. The equation well explains the dependency through surface tension, surface tensions between the particles of carbon powder.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.238-241
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• 1996

In this paper, we investigated the electrical characteristics which is d.c. and a.c. conductivity of the amorphous Te$_{80}$Se$_{10}$Sb$_{10}$thin film prepared by thermal evaporation. As the results, the d.c. conduction mechanism was followed thermally activated conduction and from the data of d.c. conductivity, the acti-vation energy and mobility gap were obtained. the d.c. conductivity was increased with temperature and a.c. conductivity also was increased with temperature and frequency. It can consider that the annealing is indispensable for higher conductivity since the activation energy decreased but d.c. and a.c. conductivity increased with annealing.aling.

• Journal of the Korean Ceramic Society
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• v.21 no.2
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• pp.135-142
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• 1984

The electrical conductivity of compositions in the system $CaO-ZrO_2$ has been measured by 2-probe tech-nique in the temperature range 350~75$0^{\circ}C$. The composition of maximum conductivity in this system is within the cubic solid-solution region close to low-calcia cubic solid-solution phase boundary. The results are as follows : 1) The maximum conductivity was found 13mol CaO in zirconia. 2) As the CaO content was increased from 13 to 21 mol% the electrical conductivity decreased for any given temperature and the activation energy increased. 3) As the firing temperature and soaking time was increased the electrical conductivity increased and activation energy decreased.

• Archives of Metallurgy and Materials
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• v.65 no.3
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• pp.1029-1033
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• 2020

In this study, we investigated the effect of Fe addition (0, 0.25, 0.50 and 0.75 wt.%) on the microstructure, mechanical properties and electrical conductivity of as-cast and as-extruded Al-RE alloys. As the Fe element increased by 0 and 0.75wt.%, the phase fraction increased to 5.05, 5.76, 7.14 and 7.38 %. The increased intermetallic compound increased the driving force for recrystallization and grain refinement. The electrical conductivity of Al-1.0 wt.%RE alloy with Fe addition decreased to 60.29, 60.15, 59.58 and 59.13 %IACS. With an increase in the Fe content from 0 to 0.75 wt.% the ultimate tensile strength (UTS) of the alloy increased from 74.3 to 77.5 MPa. As the mechanical properties increase compared to the reduction of the electrical conductivity due to Fe element addition, it is considered to be suitable for fields requiring high electrical conductivity and strength.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.243-245
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• 1994

We synthesized the conducting diamond-like carbon films using plasma-enhanced chemical vapor deposition and analysized its characteristics. We obtained the metal-containing diamond-like carbon films using $CH_4$, Ar gas and aluminum target. We observed the changes of electrical conductivity, microhardness and surface morphology according to $Ar/CH_4$ ratio, substrate bias and target bias. As the target bias and $Ar/CH_4$ ratio increase and the substrate bias decreases, the electrical conductivity and surface roughness increase. The increase of hardness involves decrease of the electrical conductivity. Metal-containing amorphous hydrogenated carbon films show improved adhesion on metal substrates compared to pure diamond-like carbon films and better electrical conductivity.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.72-74
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• 2008

We investigate the effect of mechanical damping and electrical conductivity on the dynamic performance of a new electromagnetic engine valve actuator that employs a permanent magnet. The key dynamic performance factors are the transition time and the landing velocity of the armature. Two-dimensional dynamic finite element analyses are performed to simulate a coupled system. The results show that mechanical damping and electrical conductivity have similar effects on the dynamic performance of the engine valve actuator. Subsequently, it is possible to replace the role of mechanical damping by controlling the electrical conductivity through the thickness and number of steel core laminations.

• Journal of Veterinary Clinics
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• v.15 no.2
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• pp.242-246
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• 1998

These studies were Performed to provide some basic informations for developing an automatic system in dairy farming in order that the farmers may easily and automatically detect the mastitis. Electrical conductivity of each milk sample was measured by micro-ohm meter and also the number of somatic cell was detected by somecounter. The major microorganisms causing mastitis were also investigated. The rate of infected cattle with mastitis was 33.0% among 2,540 dairy cattle and the rate of infected quarters with mastitis was 13.9 % among 9.660 quarters. When the number of somatic cell was under lost electrical conductivity of the milk was 0.073, whereas number of somatic cell was over $3{\times}10^{6}$, electrical conductivity was increased by 0.167. When electrical conductivity of milk was over 0.073, the cattle was diagnosised as mastitis. The major micmorganisms of mastitis were Staphylococcus spp. (55-60%) and Streptococcus spp. (15-20%).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.191-192
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• 2020

The purpose of this study is to measure the electrical conductivity of cementitious composites as an early step to obtain shielding performance by mixing various type of steel fiber into cementitious composites, the main building material of protection facility, to shield electromagnetic pulse (EMP) damage. Fiber such as conductors as amorphous metallic fiber, hooked steel fiber, and smooth steel fiber are mixed into cementitious composites to give electrical conductivity and measure the impedance of concrete using LCR meter. By doing this, the electrical conductivity of each type of steel fiber reinforced cementitious composites (FRCC) is compared.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.8-9
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• 2020

In this study, the electrical conductivity and shielding effect were evaluated according to the type of metal and the thickness of Metal sprayed coating. The metals used for the test are Cu, Cu-Ni and Cu-Zn, and the thicknesses were 100, 200, 500 um. Each metal sprayed coating was evaluated for electrical conductivity and electromagnetic shielding effect. When the thickness was 200 ㎛ or more, shielding effect 80 dB or more was satisfied at 1 GHz. However, in the case of Cu-Ni, there is little electrical conductivity at a thickness of 100 um or less due to the generated voids, and electromagnetic wave shielding performance cannot be expected. Therefore, To ensure electromagnetic shielding effect of structures, it is considered that the minimum thickness of metal spraying coating should be 200 um.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.213-214
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• 2022

The purpose of this study is to compare and analyze the effect of the length and volume fraction of smooth steel fiber on the electrical conductivity and shielding effectiveness of cementitious composites. As the length and volume fraction of the fiber increase, the movement of electrons becomes active and the formation of a conductive path becomes advantageous, thereby increasing electrical conductivity. Accordingly, the electrical conductivity and the shielding effectiveness showed a very close relationship. Thereafter, it is judged that research is needed to increase the shielding effect.