• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.3
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• pp.30-34
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• 2011

This study was carried out in order to evaluate the effect of coated weight and calender pressure on conductivity of printed RFID tags. The printed RFID tags have been manufactured with gravure printing and it has been well known that the efficiency of printed RFID tags is influenced by surface properties of substrate. In this study, coated paper was prepared with four different coated weight and three different calender pressure. After printing conductivity ink on coated paper, surface resistance was measured to evaluate the efficiency of the printed RFID tag. It was found that, with increasing of coated weight and calender pressure, the paper gloss, smoothness, brightness and gravure printability were improved while the surface resistance of the printed RFID tag was decreased.

• Journal of Ceramic Processing Research
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• v.20 no.1
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• pp.48-53
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• 2019

Carbon fiber reinforced SiC composites (C/SiC) have high-temperature stability and excellent thermal shock resistance, and are currently being applied in extreme environments, for example, as aerospace propulsion parts or in high-performance brake systems. However, their low thermal conductivity, compared to metallic materials, are an obstacle to energy efficiency improvements via utilization of regenerative cooling systems. In order to solve this problem, the present study investigated the bonding strength between carbon fiber and matrix material within ceramic matrix composite (CMC) materials, demonstrating the relation between the microstructure and bonding, and showing that the mechanical properties and thermal conductivity may be improved by treatment of the carbon fibers. When fiber surface was treated with a nitric acid solution, the observed segment crack areas within the subsequently generated CMC increased from 6 to 10%; moreover, it was possible to enhance the thermal conductivity from 10.5 to 14 W/m·K, via the same approach. However, fiber surface treatment tends to cause mechanical damage of the final composite material by fiber etching.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.961-968
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• 2016

The non-uniform distribution of contamination on insulator surface has appreciable effects on flashover voltage, and corresponding researches are valuable for the better selection of outdoor insulation. In this paper, two typical types of porcelain and glass insulators which are widely used in ac lines were taken as the research subjects, and their corrections of AC flashover voltage under non-uniform pollution were studied. Besides, their flashover characteristics under different ratio (T/B) of top to bottom surface salt deposit density (SDD) were investigated, including the analysis of flashover voltage, surface pollution layer conductivity and critical leakage current. Test results gave the modified formulas for predicting flashover voltage of the two samples, which can be directly applied in the transmission line design. Also, the analysis delivered that, the basic reason why the flashover voltage increases with the decrease of T/B, is due to the decrease of equivalent surface conductivity of the whole surface and the decrease of critical leakage current. This research will be of certain value in providing references for outdoor insulation selection, as well as in proposing more information for revealing pollution flashover mechanism.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.845-852
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• 2001

The characteristics of evaporation cooling of single droplet on a heated surface were studied experimentally. The two kinds of heater modules were tested to measure cooling characteristics of metal surface (high conductivity) and Teflon surface (low-energy surface, low conductivity). The results showed that time averaged heat flux during droplet evaporation increased exponentially with initial surface temperatures of brass, copper and steel. The heat flux and evaporation time did not varied with metal conductivities. However, the temperature drop after the deposition of droplet was larger on Teflon than on the metals. Thus, the correlation of interface temperature between liquid droplet and metal surface was proposed as a function of the initial surface temperature of heating materials, which could be applied to both metal and non-metal ones.

• Carbon letters
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• v.3 no.1
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• pp.17-24
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• 2002

The electrochemical behavior of the $LiCoO_2$ electrode, containing carbon black as a conductor, depends upon the nature and characteristics of carbon black. In this study, six different kinds of carbon blacks were employed to investigate the relationship between the properties of carbon blacks and electrochemical characteristics of the electrode. The larger amount of surface oxygen functional groups brought the lower electrical conductivity for the carbon blacks. The electrical conductivity of carbon blacks was closely related to the impurities such as ash and volatile content. The rate capability and cyclability of the electrode were improved with the higher conductivity of carbon blacks used. So, it can be concluded that high conductive carbon black plays an important role as a conductor for high rate of charge-discharge capability and initial efficiency.

• Carbon letters
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• v.14 no.4
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• pp.243-246
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• 2013

In this work, electroless Ni-plating on polyethylene terephthalate (PET) ultra-fine fibers surfaces was carried out to improve the electric conductivity of the fiber. The surface properties of PET ultra-fine fibers were characterized using scanning electron microscopy, X-ray diffraction, and contact angle analyses. The electric conductivity of the fibers was measured using a 4-point testing method. The experimental results revealed the presence of island-like nickel clusters on the PET ultra-fine fibers surfaces in the initial plating state, and the electric conductivity of the Ni-plated fibers was enhanced with increasing plating time and thickness of the Ni-layers on the PET ultra-fine fibers.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.6
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• pp.431-434
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• 2012

In this paper, heat-releasing sheets made of AlN powder and acryl binder as thermoset were prepared using tape casting method. The crystal structure and morphology, the thermal properties as nonvolatile solid content and thermal conductivity, and the surface resistance of heat-releasing sheet were measured by using X-ray diffractometer, field emission-scanning electron microscopy, thermo gravimetric analyzer and laser flash instrument, and surface resistance meter. It was proved that thermal conductivity is greatly affected by the content of binder in heat-releasing sheet. Superior thermal conductivity above 3.5 W/mK and suface resistance were obtained at heat-releasing sheet with above 90% of AlN powder.

• 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 Air-Conditioning and Refrigeration
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• v.10 no.3
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• pp.138-146
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• 2002

The phenomena of energy separation in vortex tubes was investigated experimentally to see the subsidiary effect of the conductivity of tube material and cooling conditions around the outer surface of the tube. The experiment was carried out with pyrex, stainless steel and copper tubes, and the heat transfer conditions of the tubes were with insulation, without in-sulation and water cooling modes respectively The results were obtained that the hot exit fluid temperature was highly affected by a change of conductivity of a tube when the outer surface was cooled by the water, while the working fluid through the tubes was air. How-ever, the cold exit temperature was little affected by the heat transfer modes on the outer surface of the vortex tube.

• Carbon letters
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• v.4 no.2
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• pp.74-78
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• 2003

Four kinds of plasma blacks were prepared by plasma pyrolysis under various metallic catalysts coated on honeycomb, and investigated the catalytic effect on the characteristics of the plasma blacks prepared under plasma pyrolysis condition. Pt, Pt-Rh, and Pd catalysts were employed as active materials to prepare the plasma blacks. In the experimental range studied, the metallic catalysts influenced on surface area, particle size, surface oxygen content and electrical conductivity of the plasma blacks prepared. It was showed that more dense particle of plasma blacks were prepared under existence of metallic catalysts. Presence of the metallic catalyst reduces the electrical resistivity of plasma blacks due to the decrease in the amount of oxygen functional groups. The highest electrical conductivity of plasma black was observed in the Pt catalyst and then followed by those Pt-Rh, Pd and bare cordierite honeycomb.