• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.1
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• pp.52-59
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• 2000

In order to develop the transparent anti-static film with higher than 80% transparency to visible light, organic conductive compounds, N-methyl phenazinium 7,7,8,8-tetracyanoquinonedimethane (TCNQ) com-plex salts was synthesized and bar-coated on the polythylene terephthalate (PET) film using polymer binders. The best surface properties were obtained when acrylic binder was used. A single layer of TCNQ made of a acrylic binder showed a surface resistance of 10\ulcorner $\Omega$/ , a conductivity of 10\ulcorner S/cm, and a transparency of 75%. An optical microscopic examination revealed that the binder was first solidi-fied on the surface of PET film over which the needle-shaped TCNQ crystals were grown. An acrylic polyol coating over the TCNQ layer improved the transparency to 87%, becuase the acrylic polyol covers the surface of TCNQ crystals to reduce the surface roughness. This conductive material has thermal stability at room temperature and 4$0^{\circ}C$ over 4,000 h.

• Journal of the Korean Ceramic Society
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• v.25 no.6
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• pp.601-608
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• 1988

The effect of SiO2 addition on sintering characteristics of 8 mole percent yttria-stabilized zirconia ceramics is investigated. As the addition of SiO2 is increased, sinterbility, microstructure, and Vickers hardness of the zirconia ceramic increased but fracture toughness and electrical conductivity are decreased. It is considered that the electrical conductivity decrease with the increase of SiO2 is due to the decrease of defect concentration of ionized oxygen. From the complex impedance measurement, it is shown that the influence of SiO2 is more dominant at the resistivity of bulk region than of grain boundary region.

• Bulletin of the Korean Chemical Society
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• v.11 no.5
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• pp.371-376
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• 1990

Polyaniline perchlorate (PAP) was synthesized by the chemical oxidation of aniline using ferric perchlorate as a strong oxidant. The electrical conductivity of PAP was measured at temperatures from - 170 to 25$^{\circ}C$. It is suggested from the conductivity measurements that the conduction mechanism for PAP is a polaron hopping conduction. From the dependence of resistivity on the reciprocal temperature, the activation energy was computed to be 0.072 eV. From the comparison of the ESR parameterks and conductivity at 25$^{\circ}C$ for the polyaniline-based conducting polymers, the conductivities of PAP, PATFB and PATS increase with increasing ${\Delta}H_{pp}$, decreasing A/B ratio and decreasing g-value, respectively. It is shown by TGA results for PAP, PATFB and PATS that the maximum weight loss rates (Pr) are 0.185 (at 269$^{\circ}C$ ), 0.366 (at 324$^{\circ}C$) and 0.23 mg/min (at 338$^{\circ}C$), respectively.

• Korean Journal of Materials Research
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• v.15 no.8
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• pp.514-517
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• 2005

Effects of nitrogen and oxygen annealing on the carrier concentration, carrier mobility, electrical resistivity and PL characteristics as well as the crystallinity of ZnO films deposited on sapphire substrates by atomic layer deposition (ALD). X-ray diffraction (XRD), Scanning electron microscope (SEM), photoluminescence (PL) analyses, and Hall measurement were performed to investigate the crystallinity, optical properties and electrical properties of the ZnO thin films, respectively. According to the XRD analysis results the crystallinity of the ZnO film annealed in an oxygen atmosphere is better than that of the ZnO film annealed in a nitrogen atmosphere. Annealing undoped ZnO films grown by ALD at a high temperature above $600^{\circ}C$ improves the crystallinity and enhances W emission but deteriorates the electrical conductivity of the flms. The resistivity of the ZnO film annealed particularly at $800^[\circ}C$ in a nitrogen atmosphere is much higher than that annealed at the same temperature in an oxygen atmosphere.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.126-127
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• 2007

Sn-filled and Fe-doped $CoSb_3$ skutterudites were synthesized by encapsulated induction melting. Single ${\delta}$-phase was successfully obtained by subsequent annealing and confirmed by X-ray diffraction analysis. Temperature dependences of Seebeck coefficient, electrical resistivity and thermal conductivity were examined from 300 K to 700 K. The positive Seebeck coefficient confirmed the p-type conduction. Electrical resistivity increased with increasing temperature, which shows that the $Sn_zCo_3FeSb_{12}$ skutterudite is highly degenerate. Thermal conductivity was reduced by Sn-filling because the filler atoms acted as phonon scattering centers in the skutterudite lattice. Thermoelectric figure of merit was enhanced by Sn filling and its optimum filling content was considered to be z=0.3 in the $Sn_zCo_3FeSb_{12}$ system.

• Polymer(Korea)
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• v.36 no.1
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• pp.22-28
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• 2012

Functionalized graphene/epoxy composites were prepared to miprove thermal conductivities of epoxy composites and to maintain electrical insulating property. Graphene oxide (GO) was prepared using Hummers method, and then GO was reacted with aluminum isopropoxide to functionalize $Al(OH)_3$ layer onto GO surface by a simple sol-gel method (Al-GO). GO and Al-GO were characterized by X-ray photoelectron spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. The analyses confirm that GO was coated with a large and dense coverage of $Al(OH)_3$. GO and Al-GO (1 and 3 wt%) were embedded in bisphenol A (DGEBA) to investigate the effects of electrical insulating property. Electrical resistivity showed that Al-GO had better insulating property than GO. Further, the thermal conductivity of GO and Al-GO/epoxy composites was higher than that of neat epoxy resins. In particular, the thermal conductivity of Al-GO/bisphenol F (DGEBF) improved by 23.3% and Al-GO/DGEBA enhanced by 21.8% compared with pure epoxy resins.

• Journal of Sensor Science and Technology
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• v.1 no.2
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• pp.165-172
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• 1992

To determine the effect of additions of trivalent and pentavalent ions on the electrical conductivity and sensing behaviour, indium and antimony were incorporated in tin oxide by the coprecipitation method. Antimony may be considered to enter the cassiterite structure as pentavalent ions, thermal energy could excite electrons from these ions into the conduction band. Similarly the indium ions would enter the lattice as $In^{3+}$ but could accept electrons from the valence band, thereby becoming monovalent or divalent. These phenomena, however, how the potential barrier existing $SnO_{2}$ by addition of two kinds of ions could influence on the sensing behaviour in comparison with their influence on the resistivity were observed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.6
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• pp.603-608
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• 2023

Carbon black with high purity and excellent conductivity is used as a conductive filler in the semiconductive compound for EHV (Extra High Voltage) power cables of 345 kV or higher. When carbon black and CNT (carbon nanotube) are applied together as a conductive filler of a semiconductive compound, stable electrical properties of the semiconductive compound can be maintained even though the amount of conductive filler is significantly reduced. In EHV power cables, since the semi-conductive layer is close to the conductor, stable electrical characteristics are required even under high-temperature conditions caused by heat generated from the conductor. In this study, the theoretical principle that a semiconductive compound applied with carbon black and CNT can maintain excellent electrical properties even under high-temperature conditions was studied. Basically, the conductive fillers dispersed in the matrix form an electrical network. The base polymer and the matrix of the composite, expands by heat under high temperature conditions. Because of this, the electrical network connected by the conductive fillers is weakened. In particular, since the conductive filler has high thermal conductivity, the semiconductive compound causes more thermal expansion. Therefore, the effect of CNT as a conductive filler on the thermal conductivity, thermal expansion coefficient, and volume resistivity of the semiconductive compound was studied. From this result, thermal expansion and composition of the electrical network under high temperature conditions are explained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.605-608
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• 2001

Molybdenum disilicide is widely used for manufacturing high-temperature heating elements owing to its low electrical resistivity, good thermal conductivity, and ability to withstand oxidation at high temperatures. MoSi$_2$heating elements with 4-5wt% of montmorillonite type bentonite as plasticzer and a small amount of Si$_3$N$_4$, ThO$_2$, and B as additives was manufactured. Extruded rods of 3.7mmø and 6.7mmø diameter and 400mm long were fabricated using a vacuum extruder, which were then sinrered for 4-5 hrs. at the max. temperrature of 140$0^{\circ}C$. After 10 minute's oxidation treatment, the diameter of the rod is reduced. The heating elements thus prepared was stable at 1$700^{\circ}C$ and the physical properties such as specific electrical resistivity, hardness, apparent densisty, thermal expansion coefficient, and bending strength were almost identical with thoes of commercial heating elements. In this study we have tried to gain the practical knowledge of manufacturing MoSi$_2$heating elements so that it may be utilized later in a research of pilot scale and eventually be transferred to industry.

• Carbon letters
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• v.24
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• pp.41-46
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• 2017

The microstructure, flexural properties, electrical conductivity, thermal conductivity and electromagnetic interference (EMI) shielding effectiveness (SE) of epoxy composites filled with multi-walled carbon nanotubes (CNTs), exfoliated graphite nanoplatelets (xGnPs) and CNT-xGnP hybrid filler were investigated. The EMI SE of the CNT-xGnP hybrid composite was higher than 25 dB at 100 MHz while that of the xGnP based composite was almost zero. The flexural modulus of the CNT-xGnP based epoxy composite continuously increased to 3.32 GPa with combined filler content up to 10 wt% while that of the CNT based epoxy composites slightly decreased to 1.96 GPa at 4 wt% CNT, and dropped to 1.57 GPa at 5 wt% loading, which is lower than that of epoxy. The CNT and CNT-xGnP samples had the same EMI SE at the same surface resistivity, because samples with the same surface conductivity have the same amount of the charge carriers.