• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.1
• /
• pp.106-113
• /
• 2013

One of feasible non-destructivity test methods for evaluation of concrete permeability is the measurement of surface resistivity. But the application to steel fiber-reinforced concrete has been limited because mis-evaluation could be caused by the steel fibers in concrete. In this study, the effect of fiber distribution on surface electrical resistivity of steel fiber-reinforced concrete was investigated through experimental program. Resistivity was measured three times on four surfaces in three rectangular and circular specimens with 0.5%, 1% and 1.5% steel fibers by volume and compared each other. The results obtained from circular specimens were consistent compared to those from rectangular specimens. And the results demonstrated that the effect of fiber distribution on surface resistivity was not significant compared to that of mixing ratio of steel fibers. In conclusion, this non-destructive testing method using measurement of surface resistivity could be used for SFRC within 0.5% steel fibers by volume.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1123-1125
• /
• 1995

In order to investigate the electrical properties for transformer oils, the dielectric properties and volume resistivity were made researches. To measure the characteristics of dielectric liquid, volume resistivity and dielectric loss, coaxial cylindrical liquid electrode was used, geometric capacitance was confirmed to 16[pF]. Highmegohm meter of VMG-1000 was used for measuring volume resistivity, the appling voltages were DC 100, 250, 500[V] in the temperature range of $20{\sim}100[^{\circ}C]$. Experiments for measuring the dielectric loss were performed at $20{\sim}120[^{\circ}C]$ in temperature range, $30{\sim}1.5{\times}10^5$[Hz] in frequency range and $300{\sim}1500$[mV] in voltage range and then, the result of experiment for the movement of carrier and the physical constants to contribute dielectric properties is introduced.

• Journal of the Korean Society of Safety
• /
• v.14 no.2
• /
• pp.83-89
• /
• 1999

The electrical properties due to mixture ratio of linear low density polyethylene(LLDPE) and ethylene vinyl acetate(EVA) films are studied. An experimental specimen is selected as LLDPE/EVA of thickness 200${\mu}{\textrm}{m}$ produced by mixture ratio of 50 : 50, 60 : 40, 70 : 30 and 80 : 2 wt%. In temperature range from $25^{\circ}C$ to 12$0^{\circ}C$, the measurement of volume resistivity using a highmegohm meter is performed within 10 minutes since each voltage of DC 100 V, 250 V, 500 V and 1000 V is applied, according to the step voltage method. From FT-IR spectrum for an analysis of physical properties, it can be confirmed that LLDPE blended with EVA shows an absence of carbonyl groups(1735 $cm^{-1}$, C=0) and ether groups(1242 $cm^{-1}$, C-O). The peak of LLDPE and EVA made of mixture ratio of 70 : 30 at 2$\theta$ =21.4$^{\circ}$ in the results of XRD is higher than the others. In the experiment for volume resistivity characteristics in order to investigate the electrical properties of specimen, it is confirmed that volume resistivity is decreased with the increase of the molecular motion and temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.224-227
• /
• 2002

In this paper, we have investigated the physical properties and electrical conduction properties of polyethylene terephthalate film due to temperature variation, and the measurement of volume resistivity used to highmegohm meter is measured from 1 to 10 minutes when the specimen applied the voltage accroding to the step voltage appling method. From FT-IR spectrum as an analysis of physical properties, the strong absorption in wavenumbers $1019[cm^{-1}]$, $1266[cm^{-1}]$ and $1752[cm^{-1}]$ observed by the C=O and benzene ring. From the analysis of DSC, the crystalline melting points of the specimen observed in the temperature $80[^{\circ}C]$ and $263[^{\circ}C]$, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.5
• /
• pp.413-417
• /
• 2019

In this study, the volume resistivity of XLPE materials with various voltage ratings was discussed. The volume resistivity of the developed XPLE nanocomposite was measured, and the conductivity mechanism of the material was also examined. The ASTM D 257 and IEC 60093 measurement methods were used for these tests. The equipment was designed to measure up to a temperature of $200^{\circ}C$, and the electrode structure was designed to maintain the thickness and temperature uniformity of the sample. The conductivity of the sample decreased with temperature, and the samples reached saturation within 500s, after which the conductivity leveled off. By analyzing the current density and the electric field, we can well explain the electric conductivity behavior of our sample with the Schottky mechanism.

• Journal of the Korean institute of surface engineering
• /
• v.44 no.4
• /
• pp.165-171
• /
• 2011

In this work, handling of sapphire substrate for LED by using an electrostatic chuck was studied. The electrostatic chuck consisted of alumina dielectric, which was doped with 1.2 wt% $TiO_2$. As the volume resistivity of alumina dielectric was decreased, the electrostatic force was increased by Johnsen-Rahbek effect. The narrower width and gap size of electrode led to the stronger electrostatic force. When alumina dielectric with $3.20{\times}10^{11}{\Omega}{\cdot}cm$ resistivity and 3 mm width/1.5 mm gap sized electrode was used, the strongest electrostatic force in this work was obtained, which value reached to ~14.46 gf/$cm^2$ at 2.5 kV for 4-inch sapphire substrate. This results show that alumina electrostatic chuck with low resistivity and fine electrode pattern is suitable for handling of sapphire substrate for LED.

• Land and Housing Review
• /
• v.2 no.2
• /
• pp.145-155
• /
• 2011

It is very important for successful construction to estimate the soil volume conversion factor of domestic weathered ground accurately and reasonably. However, it is very difficult to quantify the weathering degree of weathered ground at the field, so that the soil volume conversion factor used in Korea is often dependent upon the standard of foreign countries. Besides, the soil volume conversion factor of domestic weathered ground has been rarely studied and the use and accuracy of the soil volume conversion factor have been questioned persistingly. This study suggests a simple but robust method for estimating the soil volume conversion factor and measuring the weathering degree reasonably, and attempts to establish the utilization of a soil volume conversion factor measurement system based on experimental and analytical results. We made relationship between electrical resistivity and weathering degree presented from weathering index obtained through laboratory tests using field samples, and an estimation method of in-situ weathering degree for granites and a calculation method of soil volume conversion factor using electrical resistivity. And also, we suggested the photogrametry measurement-equipment system for measuring the volume of cargo box and the application plan of stand equipment and RFID for calculating the earth volume and distinguishing buggies in order to design the measurement system for soil volume conversion factor applicable to the field. Ultimately, the Weathered Earth-work Management Program (WEMP) was developed, so field managers may easily obtain the information about earth volume and soil volume conversion factor at the weathered ground.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.37 no.1
• /
• pp.55-62
• /
• 1988

The variation of electrical resistivity of silver particle-filled polymers with the volume percent of silver particles was investigated. Also, the relationships between the surface tension of polymer and dispersion effect of silver particles were studied to find the steep drop of electrical resisivity, in view of agglomerate morphology. The critical volume precent of silver particles varied depending on the polymer species and increased with the increasing surface tension of polymer. The steep variation of resistivity with the increasing temperature was explained with the expansion of polymer at the melting temperature of polymer. The conductive break down current increased with the increasing volume percent of silver particles in the Ag/LDPE system and that was attributed to heat of Joule taken througn the contact area between the silver particle.

• Journal of the Korean Geophysical Society
• /
• v.2 no.1
• /
• pp.75-88
• /
• 1999

A recent major subject of geophysical exploration is research into 3-D subsurface imaging with a composite information from the various geophysical data. In an attempt to interpret Schlumberger sounding data for the study area in 2-D and 3-D view, resistivity imaging was firstly performed and then pseudo-3-D resistivity volume was reconstructed by interpolating several 1-D resistivity plots. Electrical resistivity discontinuities such as fracture zone were successfully clarified in pseudo-3-D resistivity volume. The low resistivity zone mainly associated with fracture zone appears to develop down to granitic basement in the central part of the study area. Seismic velocity near the lineament is estimated to be approximately as small as 3,000 m/s, and weathering-layer for the southeastern part is interpreted to be deeper than for the northwestern part. Geophysical attributes such as electrical resistivity, seismic velocity, radioactivity for the Chojeong Area were analysed by utilizing a GIS software Arc/Info. The major fault boundaries and fracture zones were resolved through image enhancement of composite section (electrical resistivity and seismic refraction data) and were interpreted to develop in the southeastern part of the area, as characterized by low electrical resistivity and low seismic velocity. However, radioactivity attribute was found to be less sensitive to geological discontinuities, compared to resistivity and seismic velocity attributes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.24 no.10
• /
• pp.834-838
• /
• 2011

This research shows the electrical characteristic using excellent epoxy nano-composite of MgO 5.0 wt% and $SiO_2$ 0.4 wt% in mechanical strength test depending on nano-additive. First of all, volume resistance depending on nano-additive and temperature using high resistance meter (HP. 4329A) by increasing 10, 100, 1,000 V of applying voltage was measured. Moreover, temperature range of $25{\sim}120^{\circ}C$ with virgin sample was tested using TO-9B oven by Ando Company. The result showed that virgin and the samples added with MgO and $SiO_2$ had similar value of volume resistance in low temperature and low electric field region and reduced with slow slope. The nano-composite's volume resistance of sample added with MgO and $SiO_2$ had higher value than virgin sample's volume resistance in high temperature region more than $80^{\circ}C$. Moreover, the slope has steeply reduced. The volume resistance of sample added with MgO 5.0 wt% was $8.38{\times}10^{13}\;{\Omega}{\cdot}cm$ and it was 6.8 times more than virgin sample in high temperature at $120^{\circ}C$. The insulation characteristics were constant although filler has changed in low temperature region. But, in high temperature region, the value of volume resistance of sample with MgO 5.0 wt% was 7.6 times more than the virgin sample's volume resistance.