• Title, Summary, Keyword: Contact potential

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Multiscale Characteristics of Electrical Contact Resistance (전기접촉저항의 멀티스케일 특징)

  • Lee, Chang-Wook;Jang, Yong-Hoon
    • Proceedings of the KSME Conference
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    • pp.404-409
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    • 2004
  • The electrical contact resistance is here estimated using the multiscale microcontact distribution of elastic contact between rough surfaces, simulated from the Archard's model, and the electrical contact conduction theory suggested by Greenwood. These analysis confirms that the electrical contact resistance is converged to a values, larger than would be obtained if the contact spots were widely separated and hence independent. In multiscale process, the base potential is close to the value of the potential difference between the contact surface and the extremity of body, suggesting a possibility to obtain the multiscale electrical contact resistance relations.

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Contact surface element method for two-dimensional elastic contact problems

  • Liu, Zhengxing;Yang, Yaowen;Williams, F.W.;Jemah, A.K.
    • Structural Engineering and Mechanics
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    • v.6 no.4
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    • pp.363-375
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    • 1998
  • The stiffness matrix of a two-dimensional contact surface element is deduced from the principle of virtual work. The incremental loading procedure used is controlled by displacement and stress. Special potential contact elements are used to avoid the need to rearrange the FEM mesh due to variations of the contact surface as contact develops. Published results are used to validate the method, which is then applied to a turbine to solve the contact problem between the blade root and rotor in the region in which a 'push fit' connects the blade to its rotor.

Electrical Properties of TiO2 Thin Film and Junction Analysis of a Semiconductor Interface

  • Oh, Teresa
    • Journal of information and communication convergence engineering
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    • v.16 no.4
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    • pp.248-251
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    • 2018
  • To research the characteristics of $TiO_2$ as an insulator, $TiO_2$ films were prepared with various annealing temperatures. It was researched the currents of $TiO_2$ films with Schottky barriers in accordance with the contact's properties. The potential barrier depends on the Schottky barrier and the current decreases with increasing the potential barrier of $TiO_2$ thin film. The current of $TiO_2$ film annealed at $110^{\circ}C$ was the lowest and the carrier density was decreased and the resistivity was increased with increasing the hall mobility. The Schottky contact is an important factor to become semiconductor device, the potential barrier is proportional to the hall mobility, and the hall mobility increased with increasing the potential barrier and became more insulator properties. The reason of having the high mobility in the thin films in spite of the lowest carrier concentration is that the conduction mechanism in the thin films is due to the band-to-band tunneling phenomenon of electrons.

Corrosion of rebar in carbon fiber reinforced polymer bonded reinforced concrete

  • Bahekar, Prasad V.;Gadve, Sangeeta S.
    • Advances in concrete construction
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    • v.8 no.4
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    • pp.247-255
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    • 2019
  • Several reinforced concrete structures that get deteriorated by rebar corrosion are retrofitted using Carbon Fiber Reinforced Polymer (CFRP). When rebar comes in direct contact with CFRP, rebar may corrode, as iron is more active than carbon. Progression of corrosion of rebar in strengthened RC structures has been carried out when rebar comes in direct contact with CFRP. The experimentation is carried out in two phases. In phase I, corrosion of bare steel bar is monitored by making its contact with CFRP. In phase II, concrete specimens with surface bonded CFRP were casted and subjected to the realistic exposure conditions keeping direct contact between rebar and CFRP. Progression of corrosion has been monitored by various parameters: Half-cell potential, Tafel extrapolation and Linear Polarisation Resistance. On termination of exposure, to find residual bond stress between rebar and concrete, pull-out test was performed. Rebar in contact with CFRP has shown substantially higher corrosion. The level of corrosion will be more with more area of contact.

Fabrication and Characteristics of Humidity Sensing Device using $TiO_2$ Sol ($TiO_2$ Sol을 이용한 습도감지소자의 제작 및 특성)

  • Kim, Jong-Taek;Lee, Baek-Su;Kim, Cheol-Su;Yu, Do-Hyeon;Lee, Deok-Chul
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.2
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    • pp.82-86
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    • 2000
  • Humidity sensors using $TiO_2$ thin films were fabricated on the multi-electrode device by Sol-Gel method and their wettability, surface potential decays and humidity sensing characteristics were investigated. Contact angle of thin films was $28^{\cic}\;at\; 400^{\circ}C$ and surface potential decayed rapidly at $400^{\circ}C$. The specimen showed best humidity sensing characteristics at $400^{\circ}C$. From the results, they were confirmed that humidity sensing characteristics of thin films have connection with contact angle and surface potential decays.

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Characteristics of Electrowetting of Self-assembled Monolayer and Z-Tetraol Film

  • Lin Li-Yu;Noh Dong-Sun;Kim Dae-Eun
    • International Journal of Precision Engineering and Manufacturing
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    • v.7 no.3
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    • pp.35-38
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    • 2006
  • A study of electrowetting using an Octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) and Z- Tetraol 2000 perfluoropolyether lubricant as hydrophobic layers on Si and $SiO_2$ wafer was performed. The $SiO_2$ layer used as insulating layer was thermally grown on the silicon wafer to a thickness of 220-230 nm. The results demonstrated that the contact angle decreased from $100^{\circ}$ to $80^{\circ}$ at 28 V applied potential on $SiO_2$ wafer coated with OTS and the contact angle appeared to be reversible. However, the contact angle on the $SiO_2$ wafer coated with Z- Tetraol 2000 was not observable at 28 V applied potential. Furthermore, the contact angle on the Si wafer coated with OTS or Z- Tetraol 2000 appeared to be irreversible due to the generation of electrolysis in the droplet. It is concluded that it is feasible to use SAM as a hydrophobic layer in electrowetting applications.

Improved Contact Characteristics in a Single Tin-Oxide Nanowire Device by a Selective Reactive Ion Etching (RIE) Process (선택 건식에칭에 의한 단일 산화주석 나노와이어 소자의 접촉 특성 개선)

  • Lee, Jun-Min;Kim, Dae-Il;Ha, Jeong-Sook;Kim, Gyu-Tae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.1
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    • pp.130-133
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    • 2010
  • Although many structures based on $SnO_2$ nanowires have been demonstrated, there is a limitation towards practical application due to the unwanted contact potential between the metal electrode and the $SnO_2$ nanowire. This is mostly due to the presence of the native oxide layer that acts as an insulator between the metal contact and the nanowire. In this study the contact properties between Ti/Au contacts and a single $SnO_2$ nanowire was compared to the electrical properties of a contact without the oxide layer. RIE(Reactive Ion Etching) is used to selectively remove the oxide layer from the contact area. The $SnO_2$ nanowires were synthesized by chemical vapor deposition (CVD) and dispersed on a $Si/Si_3N_4$ substrate. The Ti/Au (20nm/100nm) electrodes were formed bye-beam lithography, e-beam evaporation and a lift-off process.

Relative Measurement of Differential Electrode Impedance for Contact Monitoring in a Biopotential Amplifier

  • Yoo, Sun-K.
    • International Journal of Control, Automation, and Systems
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    • v.5 no.5
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    • pp.601-605
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    • 2007
  • In this paper, we propose a simple and relative electrode contact monitoring method. By exploiting the power line interference, which is regarded as one of the worst noise sources for bio-potential measurement, the relative difference in electrode impedance can be measured without a current or voltage source. Substantial benefits, including no extra circuit components, no degradation of the body potential driving circuit, and no electrical safety problem, can be achieved using this method. Furthermore, this method can be applied to multi-channel isolated bio-potential measurement systems and home health care devices under a steady measuring environment.

Effects of Water Treating on Surface Properties of Epoxy Insulation Materials (Epoxy 절연재료이 표면특성에 미치는 수분처리의 영향)

  • Lim, Kyung-Bum;Lee, Duck-Chool
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.10
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    • pp.553-558
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    • 2000
  • This paper deals with change of contact angle, surface potential decay, surface resistivity and XPS of water-treated epoxy insulator. From the experimental results on the contact angle was reduced from $74^{\circ}$to $24^{\circ}$ due to the formation of polar hydroxyl groups on surface which was associated with intermolecular reaction between epoxy chains of three-dimensional network structure and water molecules. From the experimental results in the surface potential decay of water treated-samples, it was found that the accumulation of charge is decreased and the surface potential decay time is shortened by the interaction of polar hydroxyl groups induced on the treated surface as the increment of treatment time. The positive charging on the treated surface compared with negative charging is relatively lowered by the induction of polar hydroxyl groups. The surface resistivity was changed from $10^{15}[{\Omega}/cm^2$] to $10^{12}[{\Omega}/cm^2$] caused by water treatment. From XPS, it was found that the changes affected by the surface degradation of epoxy were caused by the generation of carboxyl groups through the chain decomposition and recombination with oxygen molecules in the air.

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