• Title/Summary/Keyword: Thermal resistivity

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A Study on the Utilization of Waste Foundry Sand as Backfill Material for Underground Electric Utility Systems (방식사의 지하 전력시설용 되메움재 활용에 관한 연구)

  • 이대수;홍성연;김경열
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.665-672
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    • 2002
  • In this paper, the utilization of waste foundry sand produced in the molding process is studied as a backfill material for underground electric utility systems such as concrete box structures and pipe lines for power supply. The physical, chemical and thermal properties for waste foundry sand are investigated for mechanical stability, environmental hazard and power transmission capacity. Also its properties are compared with the natural river sand. The test results show that waste foundry sand can be utilized for underground concrete box structures as a backfill material; however, it can not be applied to underground pipe lines due to high thermal resistivity or low power transmission capacity.

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A Study on the Surface Degradation Phenomena and Electrical Properties of Polymer Composite Materials (고분자 복합재료의 표면 열화 현상과 전기적 특성에 관한 연구)

  • Park, Jae-Sae;Lim, Kyung-Bum
    • Proceedings of the KIEE Conference
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    • 2002.06a
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    • pp.75-78
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    • 2002
  • In this paper, we investigated the change of wettability, surface potential decay and surface resistivity caused by thermal-treated and plasma-treated FRP respectively for finding out the influence of electrical characteristics on the surface of polymer composites. For the change of wettability, the contact angle of thermal-treated specimen with the high temperature of 200$^{\circ}C$ increased. But that of plasma-treated specimen decreased. The characteristic of surface potential decay shows the tendency of the remarkable decrease on plasma-treated specimens, but no difference on thermal-treated specimen compared with untreated one. Also, for the surface resistivity, it shows the same trend compared with the change of contact angle. We can conclude that the degradation phenomena of epoxy surface are dominated by the induction of hydrophilicity and hydrophobicity.

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Degradation Properties of Epoxy Resin Used in Indoor (옥내용 에폭시 수지의 열화 특성)

  • 남기동;정중일;연복희;허창수;박영두
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.57-60
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    • 2000
  • In this paper, study on the properties of the thermal degradated epoxy resin which is used in indoor insulation apparatus is performed to investigate the problems of the decreasing insulation characteristics and crack in the indoor insulation apparatus. As a parameter of variation, SEM, contact angle, surface resistivity, relative dielectric constant and weight loss are measured. As the results of the above measurements, the contact angle and surface resistivity of the epoxy resin has increased to 200$^{\circ}C$ in but at the above 200$^{\circ}C$ the values have decreased. The relative dielectric constants the thermal treated samples have increased on with the temperature increase. We find the volatile components of the epoxy resin compound has disappeared during thermal degradation by SEM. The insulation properties of the epoxy resin have increased by the 200$^{\circ}C$ but decreased in the above 200$^{\circ}C$.

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The Quantitative Evaluation of Aging State of Field Composite Insulators Based on Trap Characteristics and Volume Resistivity-Temperature Characteristics

  • Liang, Ying;Gao, Li-Juan;Dong, Ping-Ping;Gao, Ting
    • Journal of Electrical Engineering and Technology
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    • v.13 no.3
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    • pp.1355-1362
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    • 2018
  • In order to obtain a better understanding of the ageing process of the field composite insulators, it is necessary to explore a quantitative-valuation method for the aging state evaluation. And the linear relationship between volume resistivity and temperature is proposed. In this paper, the composite insulators with different lengths of operating lives from two manufacturers were tested. The relationship between trap characteristics and volume resistivity-temperature characteristics were analyzed based on Thermal Stimulated Current (TSC), volume resistivity-temperature test, Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, the application of trap characteristics in the quantitative evaluation of aging state of composite insulators was discussed. The results showed that there was a general negative correlation between the relative variation ratio of trap charges and the volume resistivity-temperature characteristics. Meanwhile, the physicochemical properties would change with the aging time, which would result in the increasing of electron traps. Combined with the TSC and volume resistivity test results, the trap characteristic thresholds which indicated the serious age of the composite insulators had been proposed.

Development of Diamond-like Carbon Film as Passivation Layers for Power Transistors

  • Chang, Hoon;Lee, Hae-Wang;Chung, Suk-Koo;Shin, Jong-Han;Lim, Dae-Soon;Park, Jung-Ho
    • The Korean Journal of Ceramics
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    • v.3 no.2
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    • pp.92-95
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    • 1997
  • Because of the novel characteristics such as chemical stability, hardness, electrical resistivity and thermal conductivity, diamond-like carbon (DLC) film is a suitable material for the passivation layers. For this purpose, using the PECVD, DLC films were synthesized at room temperature. The adhesion and the hardness of the DLC films deposited on Si an SiO2 substrate were measured. The resistivity of 5.3$\times$$10^8$$\Omega$.cm was measured by automatic spreading resistance probe analysis method. The thermal conductivities of different DLC films were measured and compared with that of phospho silicate glass (PSG) film which is commonly used as passivation layers. The thermal conductivity of DLC film was improved by increasing hydrogen flow rate up to 90 sccm and was better than that of PSG film. The patterning techniques of the DLC film developed using the RIE and the lift-off method to form 5$\mu\textrm{m}$ line. Finally, the thermal characteristics of the power transistor with the DLC film as passiviation layer was analyzed.

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Interfacial Properties and Curing Behavior of Carbon Fiber/Epoxy Composites using Micromechanical Techniques and Electrical Resistivity Measurement (Micromechanical 시험법과 전기적 고유저항 측정을 이용한 탄소섬유강화복합재료의 계면 물성과 경화거동에 관한 연구)

  • 이상일;박종만
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.11a
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    • pp.17-21
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    • 2000
  • Logarithmic electrical resistivity of the untreated or thin diameter carbon fiber composite increased suddenly to the infinity when the fiber fracture occurred by tensile electro-micromechanical test, whereas that of the ED or thick fiber composite increased relatively broadly up to the infinity. Electrical resistance of single-carbon fiber composite increased suddenly due to electrical disconnection by the fiber fracture in tensile electro-micromechanical test, whereas that of SFC increased stepwise due to the occurrence of the partial electrical contact with increasing the buckling or overlapping in compressive test. Electrical resistivity measurement can be very useful technique to evaluate interfacial properties and to monitor curing behavior of single-carbon fiber/epoxy composite under tensile/compressive loading.

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Preparation and Characterization of Vapor-Grown Carbon Nanofibers-Reinforced Polyimide Composites by in-situ Polymerization (In-situ 중합법에 의한 기상성장 탄소나노섬유/폴리이미드 복합재료의 제조 및 물성)

  • Park, Soo-Jin;Lee, Eun-Jung;Lee, Jae-Rock;Won, Ho-Youn;Moon, Doo-Kyung
    • Polymer(Korea)
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    • v.31 no.2
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    • pp.117-122
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    • 2007
  • In this work, the mechanical and electrical properties, and thermal stability of vapor-grown carbon nanofibers/polyimide (VGCNFs/PI) composite film synthesized by in-situ polymerization were investigated in terms of tensile properties, volume resistivity and thermogravimetric analysis (TGA), respectively. From the results, the addition of VGCNFs with a certain amount into polyimide led to obvious improvement in tensile strength. The volume resistivity of the films was decreased with increasing the VGCNFs content and the electrical percolation threshold appeared between 1 and 3 wt% of VGCNFs content, which was probably caused by the formation of interconnective structures among the VGCNFs in a composite system. The thermal stability of the film was higher than that of pure PI one. This result indicated that the crosslinking of VGCNFs/PI Composites was enhanced by well-distribution of YGCNFs in PI resin, resulting in the increase of the thermal stability of the resulting composites.

Effect of Post-deposition Rapid Thermal Annealing on the Electrical and Optical Properties of ZTO/Ag/ZTO Tri-layer Thin Films (급속열처리에 따른 ZTO/Ag/ZTO 박막의 전기적, 광학적 특성 개선 효과)

  • Song, Young-Hwan;Eom, Tae-Young;Heo, Sung-Bo;Kim, Daeil
    • Journal of the Korean Society for Heat Treatment
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    • v.30 no.4
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    • pp.151-155
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    • 2017
  • The ZTO single layer and ZTO/Ag/ZTO tri-layer films were deposited on glass substrates by using the radio frequency (RF) and direct current (DC) magnetron sputtering and then rapid thermal annealed (RTA) in a low pressure condition for 10 minutes at 150 and $300^{\circ}C$, respectively. As deposited tri-layer films show the 81.7% of visible transmittance and $4.88{\times}10^{-5}{\Omega}cm$ of electrical resistivity, while the films annealed at $300^{\circ}C$ show the increased visible transmittance of 82.8%. The electrical resistivity also decreased as low as $3.64{\times}10^{-5}{\Omega}cm$. From the observed results, it is concluded that rapid thermal annealing (RTA) is an attractive post-deposition process to optimize the opto-elecrtical properties of ZTO/Ag/ZTO tri-layer films for the various display applications.

Effects of Heat Treatment on Electrical and Mechanical Properties of Glass Fiber Reinforced Epoxy (열처리가 유리섬유 강화 복합재료의 전기적 및 기계적 성질에 미치는 영향)

  • 이백수;이덕출
    • 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.

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Formation of nickel oxide thin film and analysis of its electrical properties

  • Noh, Sang-Soo;Seo, Jeong-Hwan;Lee, Eung-Ahn;Lee, Seon-Gil;Park, Yong-Joon
    • Journal of Sensor Science and Technology
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    • v.14 no.1
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    • pp.52-55
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    • 2005
  • Ni oxide thin films with thermal sensitivity superior to Pt and Ni thin films were formed through annealing treatment after Ni thin films were deposited by a r.f. magnetron sputtering method. Resistivity values of Ni oxide thin films were in the range of $10.5{\mu}{\Omega}cm$ to $2.84{\times}10^{4}{\mu}{\Omega}cm$ according to the degree of Ni oxidation. Also temperature coefficient of resistance(TCR) values of Ni oxide thin films depended on the degree of Ni oxidation from 2,188 ppm/$^{\circ}C$ to 5,630 ppm/$^{\circ}C$ in the temperature range of $0{\sim}150^{\circ}C$. Because of the high linear TCR and resistivity characteristics, Ni oxide thin films exhibit much higher sensitivity to flow and temperature changes than pure Ni thin films and Pt thin films.