• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.1
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• pp.71-76
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• 2006

The electrical characteristics of concrete block including a reinforcing rod in the foundation of the housing was fundamentally reviewed. It was tried to apply the substitutional earthing electrode in the foundation of the building. In order to identify the difference in the earthing resistance between mortar block and concrete block model, those models including a reinforcing rod in their inside were prepared and investigated for the earthing resistance. In results, the earthing resistance was largely affected by the block's resistivity compared to the change of resistance in reinforcing rods and the ground resistivity.

• Journal of Magnetics
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• v.13 no.2
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• pp.61-64
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• 2008

We studied the effect of the variation of the lattice constant on the electrical properties of $SrRuO_3$ thin films. In order to obtain films with different volumes, we varied the substrate temperature and oxygen pressure during the growth of the films on $SrTiO_3$ (001) substrates. The films were grown using a pulsed laser deposition method. The X-ray diffraction patterns of the grown films at low temperature and low oxygen pressure indicated the elongation of the c-axis lattice constant compared to that of the films grown at a higher temperature and higher oxygen pressure. The in-plane strain states are maintained for all of the films, implying the expansion of the unit-cell volume by the oxygen vacancies. The variation of the electrical resistance reflects the temperature dependence of the resistivity of the metal, with a ferromagnetic transition temperature inferred form the cusp of the curve being observed in the range from 110 K to 150 K. As the c-axis lattice constant decreases, the transition temperature linearly increases.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.174-180
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• 1998

In this work, the properties of FRP, which is applied recently in the composite insulating materials, by thermal treatment were investigated. The specimens were epoxy glass laminates fabricated by thermal press method and had the volume content of 46[%] cutted $45^{\circ}C$ in the fiber direction and 1.0[mm] thickness. The experimental results showed that the amount of weight loss, wettability, surface potential, and surface resistivity increased up to 200[$^{\circ}C$] as a function of temperature. Usually, most degradations caused the hydrophilic to decrease the contact angle. But, in this work on thermal-degradated FRP, we can confirm the introduction of hydrophobic properties by cross-linking and the ablation of polar small-molecules rather than chain scission and oxidation. Finally, weight loss and contact angle increased. These phenomena show the existence of hydrophobic surface. With the change to the hydrophobic surface and the electrical potential and resistivity on FRP surface increased. But, the dielectric properties and tensile stength are decreased.

• Korean Journal of Materials Research
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• v.5 no.8
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• pp.921-928
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• 1995

MoSi$_2$heating elements were fabricated using MoSi$_2$, powder prepared by SHS. Their apparent density, electrical resistivity, bending strength and victors hardness were measured as a function of sintering temperature, time and the amount of ceramic additives. The additives were A1$_2$O$_3$, SiO$_2$and bentonite which were added as a plastisizer. The electrical resistivity of MoSi$_2$decreased with the increase in the apparent density as expected. It decreased when the additives were added and the increase was the largest for the case of SiO$_2$. The bending strength and hardness decreased when the grain size becomes larger which is opposite to the expectation from the Hall-Petch type relation. Instead, they showed inverse proportionality with the volume fraction of pores probably in an exponential manner. The strength and hardness also decreased with the additives.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.984-990
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• 2014

Polymers are the most commonly used di-electrics because of their reliability, availability, ease of fabrication and cost. The commercial and industrial demand for advanced polymeric materials which are capable of being used in harsh environment is need of the hour. The study of the effect of electron beam irradiation on polymeric materials is an area of rapidly increasing interest. This paper discusses the resultant beneficial effects of electron beam irradiation on the SiR-EPDM blend having 50:50 composition. The changes in mechanical and electrical properties of SiR-EPDM blend which are exposed to three different doses of electron beam radiation namely 5 Mrad, 15 Mrad and 25 Mrad are presented. The irradiated blends are analyzed for their electro-mechanical and physico chemical properties. The electrical changes induced by irradiation are investigated by arc resistance, surface resistivity and volume resistivity measurements as per ASTM standards. The mechanical changes are observed by the measurement of tensile strength and elongation at break. Physico chemical investigation has been done using the FTIR, in order to investigate the irradiation induced chemical changes.

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.31-34
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• 2012

The addition of nano/micro silica into unsaturated polyester resin (UPR) results in the improvement of the electrical properties of Silica-UPR composites. The surface, volume resistivity, dielectric strength, dissipation factor and dry arc resistivity of nano silica-UPR composites were found to improve significantly. The effects of the nano and micro fillers in UPR have been evaluated. They are presented in this paper. To evaluate the electrical properties of the nano & micro composites, all the measurements were done as per the prescribed methods in ASTM. It was observed that the addition of nano silica improves the electrical properties as compared to micro silica. The better dispersion of silica particles in unsaturated polyester resin enhances the electrical properties of silica-UPR composites.

• Elastomers and Composites
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• v.33 no.4
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• pp.246-254
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• 1998

In order to investigate the characteristics of resistance and conduction of vulcanized styrene butadiene rubber (SBR)/ carbon black (CB) composites, surface/ volume resistivity, point to point resistance, decay time, and electrical conduction experiments with four different kinds of non-conductive carbon black were measured. When about 50phr of carbon black were loaded in SBR, all resistivites suddenly decreased and critical region (Rc) was shown. Current densities of SBR/CB composites showed critical point (Pc) and increased with the electric fields. Electrical conduction mechanisms of SBR/CB composites could be considered as the ohmic conduction at low electric fields and the space charge limited conduction (SCLC) at high electric fields, respectively.

• Journal of Magnetics
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• v.18 no.1
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• pp.39-42
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• 2013

We studied the structural and electrical properties of $SrRuO_3$ thin films grown on $SrTiO_3$ (110) substrate. High resolution X-ray diffraction measurement of the grown film showed 1) very sharp peaks for $SrRuO_3$ film with a very narrow rocking curve with FWHM = $0.045^{\circ}$ and 2) coherent growth behavior having the same in-plane lattice constants of the film as those of the substrate. The resisitivity data showed good metallic behavior; ${\rho}$ = 63(205) ${\mu}{\Omega}{\cdot}cm$ at 5 (300) K with a residual resistivity ratio of ~3. The observed kink at ${\rho}(T)$ showed that the ferromagnetic transition temperature was ~10 K higher than that of $SrRuO_3$ thin film grown on $SrTiO_3$ (001) substrate. The observed rather lower RRR value could be partially due to a very small amount of Ru vacancy generally observed in $SrRuO_3$ thin films grown by PLD method and is evident in the larger unit-cell volume compared to that of stoichiometric thin film.

• The Journal of Engineering Geology
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• v.25 no.2
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• pp.251-263
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• 2015

Geological mapping, borehole drilling, electrical resistivity, and seismic tomography surveys were conducted in order to map underground cavities and better understand the mechanisms driving subsidence in a limestone region in Korea. Limestone outcrops in the study area generally alternate between calcite-rich and calcite-poor rock. The results reveal that in areas experiencing subsidence, cavities occur mainly around soil-rock boundaries at depths of 7~14 m. These results are based on comparative analyses of electrical resistivity, seismic tomography, and borehole logging data. The volumes of the cavities are relatively small in a range of 558~835 ㎥ and they have a shape typical of suffosion sinkholes, which are typically found where sandy soils overlie bedrock cavities.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.142-147
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• 2007

A series of styrene-butadiene-styrene/aluminium (SBR/Al) composites have been compounded with different weight ratios of Al. The prepared SBR-Al systems have been characterized for different mechanical properties such as tensile strength, tensile modulus and surface hardness have improved with the increase in content of Al in SBR matrix. This may is because of the increase in polymer-filler interaction. The electrical properties such as volume conductivity, surface resistivity, dielectric constant, dissipation factor (tan delta), and break down voltage of SBR/Al composites have been measured with reference to volume fraction $(V_{f}),$ frequency and temperature. The resistance of the SBR-Al composites is found to be ohmic. The voltage-current (V-I) characteristics for SBR-Al also exhibit a linear relationship indicating the ohmic behavior.