• Title/Summary/Keyword: Contact potential

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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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Contact Modeling of Arbitrary Shaped Bodies in Space (공간상에서 자유 곡면 물체의 접촉 모델링)

  • Park, Su-Jin;Shin, Ki-Bong;Sohn, Jeong-Hyun;Yoo, Wan-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.4
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    • pp.544-550
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    • 2003
  • The contact analyses of arbitrary shaped spatial bodies are important in the study of multi-body dynamics. This paper presents a method fur calculating contact force between bodies in space. At each integration time step, the proposed method finds potential contact points on bodies and then calculates the penetration, the velocity of penetration, and the contact force. A continuous analysis method is adopted to calculate the contact force. To get contact points accurately on their outlines, a new algorithm is developed. The proposed algorithm is tested and compared the results of DADS. As applications, the contact of two steel balls, spatial pendulums, and the problem of a ball and bat are demonstrated.

Surface potential mapping using a functional AFEM cantilever (기능성 원자간력 현미경 캔틸레버를 이용한 표면 전위 측정)

  • Suh Moon Suhk;Lee Churl Seung;Lee Kyoung Il;Shin Jin-Koog
    • 정보저장시스템학회:학술대회논문집
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    • 2005.10a
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    • pp.53-55
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    • 2005
  • The surface potential variations are measured, according to the enhanced measuring speed and voltage sensitivity, using an active device, such as a field effect transistor $(FET)^{1-3}$. In this study, the surface potential was mapped in the patterned $SiO_2$ medium at room temperature. An improved FET-tip cantilever, which has a source, a drain, and an n- channel, was used in this study. The potential images were analyzed both in the contact mode and the non-contact mode, using only a pre-amplifier system instead of a lock-in the amplifier.

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Prediction of contact lengths between an elastic layer and two elastic circular punches with neural networks

  • Ozsahin, Talat Sukru;Birinci, Ahmet;Cakiroglu, A. Osman
    • Structural Engineering and Mechanics
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    • v.18 no.4
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    • pp.441-459
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    • 2004
  • This paper explores the potential use of neural networks (NNs) in the field of contact mechanics. A neural network model is developed for predicting, with sufficient approximation, the contact lengths between the elastic layer and two elastic circular punches. A backpropagation neural network of three layers is employed. First contact problem is solved according to the theory of elasticity with integral transformation technique, and then the results are used to train the neural network. The effectiveness of different neural network configurations is investigated. Effect of parameters such as load factor, elastic punch radii and flexibilities that influence the contact lengths is also explored. The results of the theoretical solution and the outputs generated from the neural network are compared. Results indicate that NN predicted the contact length with high accuracy. It is also demonstrated that NN is an excellent method that can reduce time consumed.

THE k-ALMOST RICCI SOLITONS AND CONTACT GEOMETRY

  • Ghosh, Amalendu;Patra, Dhriti Sundar
    • Journal of the Korean Mathematical Society
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    • v.55 no.1
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    • pp.161-174
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    • 2018
  • The aim of this article is to study the k-almost Ricci soliton and k-almost gradient Ricci soliton on contact metric manifold. First, we prove that if a compact K-contact metric is a k-almost gradient Ricci soliton, then it is isometric to a unit sphere $S^{2n+1}$. Next, we extend this result on a compact k-almost Ricci soliton when the flow vector field X is contact. Finally, we study some special types of k-almost Ricci solitons where the potential vector field X is point wise collinear with the Reeb vector field ${\xi}$ of the contact metric structure.

Surface Properties of Epoxy Composites by Plasma Treatment (플라즈마처리에 따른 에폭시 복합재료의 표면특성)

  • 임경범;이백수;이덕출
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.10
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    • pp.821-827
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    • 2001
  • In this study performed to identify a degradation mechanism in macromolecular insulating material, the contact angel, surface potential decay, surface resistivity, and XPS analysis were compared after exposure of FRP laminate to plasma discharge. In the case of contact angle, the surface of specimen untreated showed weak hydrophobic property of 73。. However, the contact angle was decreased to 20。in the plasma-treated specimen. In the case of chemical changes arising form plasma treatment, carboxl radicals were generated mainly in the surface treated, which was rapidly changed to the hydrophilic one. In the corona potential decay study to determine the electrical changes of the surface, positive charges were rapidly decreased when compared with negative charges, leading to negative property in the surface of specimen not treated. However, in the case of the hydrophilic surface, lots of carboxl radicals acting as positive polarity were generated, resulting in positive surface. Owing to such positive surface, charges of negative polarity applied were rapidly decreased.

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Analysis of the Surface Degradation in UV-irradiated High-Temperature Vulcanized Silicone Rubber (자외선 조사된 HTV 실리콘 고무의 표면열화 분석)

  • 연복희;이태호;허창수;이종한
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.5
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    • pp.411-419
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    • 2000
  • In this paper we have investigated the surface degradation by ultraviolet-irradiation in high-temperature vulcanized silicone rubber. Through the measurement of surface potential decay by corona-charging and of contact angle it is found that the change of surface electrostatic properties and the decrease of contact angle under UV-radiation. For the changes in micro-morphological and chemical structure of the UV-treated silicone rubber we utilized several analytical techniques such as SEM, ATR-FTIR,XPS. From this study it is shown that the chemical reactions(scissoring of side chain(S-$CH_3$) cross-linking and branching) occur on the surface of silicone rubber during the UV-irradiation. Also we obtained the results of the loss of low molecular weight chain by cross-linking and oxidation reaction.

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Surface properties of epoxy/glass Eber composites by environmental conditions (사용 환경조건에 따른 Epoxy/Glass Fiber 복합재료의 표면특성)

  • 임경범;이백수;황명환;김윤선;유도현;이덕출
    • Journal of the Korean Vacuum Society
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    • v.9 no.3
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    • pp.279-284
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    • 2000
  • In order to analysis the degradation process of epoxy/glass fiber for outdoor condition, FRP laminate was exposed to high temperature and water. Then the degradation process was evaluated by comparing contact angle, surface potential decay, and surface resistivity. For the change of wettability, the contact angle of thermal-treated specimen with the high temperature of $200^{\circ}C$ increased. But that of water-treated specimen decreased. The characteristic of surface potential decay shows the tendency of the remarkable decrease on water-treated specimens, but increase 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.

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