• Title/Summary/Keyword: charge density

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A Device Parameter Extraction Method for Thin Film SOI MOSFETs (얇은 박막 SOI (Silicon-On-Insulator) MOSFET 에서의 소자 변수 추출 방법)

  • Park, Sung-Kye;Kim, Choong-Ki
    • Proceedings of the KIEE Conference
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    • 1992.07b
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    • pp.820-824
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    • 1992
  • An accurate method for extracting both Si film doping concentration and front or back silicon-to-oxide fixed charge density of fully depleted SOI devices is proposed. The method utilizes the current-to-voltage and capacitance-to-voltage characteristics of both SOI NMOSFET and PMOSFET which have the same doping concentration. The Si film doping concentration and the front or back silicon-to-oxide fixed charge density are extracted by mainpulating the respective threshold voltages of the SOI NMOSFET and PMOSFET according to the back surface condition (accumulation or inversion) and the capacitance-to-voltage characteristics of the SOI PMOSFET. Device simulations show that the proposed method has less than 10% errors for wide variations of the film doping concentration and the front or the back silicon-to-oxide fixed charge density.

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Effects of Polyelectrolyte Dosage, Kaoline Particles and pH on Flocculation of Humic Acid by Catonic Polyelectrolytes

  • Kam, Sang-Kyu;Kim, Dae-Kyoung;Lee, Min-Gyu
    • Journal of Environmental Science International
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    • v.12 no.8
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    • pp.861-870
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    • 2003
  • Using a simple continuous optical technique, coupled with measurements of zeta potential, the effects of polyelectrolyte dosage, kaoline particles and pH on flocculation of humic acid by several cationic polyelectrolytes, have been examined. The charge density of a polyelectolyte is important in determining the optimum dosage and in the removal of humic acid. The optimum dosage is less for the polyelectrolytes of higher charge density and is the same regardless of the presence of kaoline particles of different turbidity. At the dosage, the removal of humic acid is higher for the polyelectrolytes of higher charge density and the zeta potential of humic acid approaches to near zero, With increasing pH of humic acid, the optimum dosage increases and the flocculation index value obtained at the dosage decreases in the following pH 7 > pH 5 > pH 9, regardless of polyelectrolytes.

A Numerical Model for Non-Equilibrium Electroosmotic Flow in Micro- and Nanochannels (마이크로/나노 채널에서의 비평형 전기삼투 유동 모사를 위한 수치모델)

  • Kwak Ho Sang;Jr. Ernest. F. Hasselbrink,
    • 한국전산유체공학회:학술대회논문집
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    • 2004.10a
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    • pp.161-164
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    • 2004
  • A finite volume numerical model is developed for simulating non-equilibrium electroosmotic flow in micro- and nanochannels. The Guoy-Chapman model is adopted to compute the flow and electric potential. The Nernst-Planck equation is employed to trace unsteady transports of ionic species, i.e., time-dependent net charge density. A new set of boundary conditions based on surface charge density are designed rather than using the conventionally-employed zeta potential. A few issues for an efficient computation of electroosmotic flows are discussed. Representative computational examples are given to illustrate the robustness of the numerical model.

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A Study on The Distribution of Surface Charge Density on Polymer Insulators (고분자애자의 표면전하밀도 분포에 관한 연구)

  • Yang, J.J.;Hwang, B.M.;Kim, K.S.;Lee, J.H.
    • Proceedings of the KIEE Conference
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    • 1997.11a
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    • pp.354-356
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    • 1997
  • In this paper, we study the distribution of surface charge density on polymer insulators. The electric field of polymer insulators is calculated by axisymetric 3-D FEM with dc source. And the surface charge density is calculated by electric scalar potential and boundary condition for electrostatic fields. Simulation model is the inclined type polymer insulator with a shed.

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Surface Charge Density and Acidic Characteristics of $SO_4^{2-}/Al_2O_3$ ($SO_4^{2-}/Al_2O_3$의 표면전하밀도와 산적특성)

  • 함영민;홍영호;장윤호
    • Journal of the Korean Ceramic Society
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    • v.30 no.11
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    • pp.933-940
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    • 1993
  • SO42-/Al2O3 powder was prepared by the coprecipitation method from the Al(NO3)3.9H2O and NH4OH and followed by being treated with various concentrations of sulfuric acid. The characterization of these powders was performed with XRD, BET and FT-IR. The surface charge density at alumina/KCl(aq) interface was measured by potentiometric titration method. From the experimental data it was shown that acid strength, specfic surface area, and structure of surface treated alumina were independent on the amount of exchanged SO42-. However, the acid amounts of alumina were increased with the amounts of SO42- formed on alumina surface. The relation between the acid amount of SO42- ion exchanged alumina surface and the surface charge density for SO42-/Al2O3/KCl(aq) interface was investigated.

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Charge Accunmulation Characteristics in LDPE (저밀도 폴리에틸렌의 전하축적 특성)

  • ;;Tatsuo Takada
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.41 no.1
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    • pp.42-49
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    • 1992
  • Charge accumulation characteristics in low density polyethylene (LDPE) has been discussed based upon the internal charge distrubution measured by the pulsed electroacoustic technique. When the negative voltage with respect to earth is applied to the upper electrode, the negative charges near the anode and the positive charges near the cathode are accumulated in LDPE. Also, there was an asymmetric behavior of charge accumulation exhibiting that the charge accumulation near the anode keeps increasing whereas that near the cathode increases first and then decreases. Besides, under the present test conditions the internal charge distrubution becomes stabilized eventually. When the positive voltage with respect to earth is applied to the upper electrode, on the other hand, no such asymmetric charge accumulation was found. Therefore, it can be concluded that the heterocharges are accumulated at the surface region of LDPE subjected to high do voltages and that the begavior of charge accumulation depends on the polarity of do voltage and the position of charge accumulation.

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Analysis of the Ionized Fields around HVDC Transmission Line by the Use of the Charge Simulation Method (전하중첩법을 이용한 직류 송전선 주변 이온장 해석)

  • Min Suk-Won;Song Ki-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.6 no.6
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    • pp.478-485
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    • 2005
  • This paper analysed the ionized fields around HVDC transmission line by the use of the charge simulation method. As this is very complex and expressed by a non-linear partial differential equations, it is hard to solve problems analytically. So, we developed a computer program which can apply in multi-polar HVDC transmission line with conductor bundles and calculated conductor surface gradient, corona current density and ion charge density to prove validity of a proposed algorithm in this paper.

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Bipolar Transport Model of Single Layer OLED for Embedded System

  • Lee, Jung-Ho;Han, Dae-Mun;Kim, Yeong-Real
    • Proceedings of the Korea Society of Information Technology Applications Conference
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    • 2005.11a
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    • pp.237-241
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    • 2005
  • We present a device model for organic light emitting diodes(OLEDs) which includes charge injection, transport, recombination, and space charge effects in the organic materials. The model can describe both injection limited and space charge limited current flow and the transition between them. Calculated device current, light output, and quantum and power efficiency are presented for different cases of material and device parameters and demonstrate the improvements in device performance in bilayer devices. These results are interpreted using the calculated spatial variation of the electric field, charge density and recombination rate density in the device. We find that efficient OLEDs are possible for a proper choice of organic materials and contact parameters.

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Effects of blast-induced random ground motions on the stochastic behaviour of industrial masonry chimneys

  • Haciefendioglu, Kemal;Soyluk, Kurtulus
    • Structural Engineering and Mechanics
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    • v.43 no.6
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    • pp.835-845
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    • 2012
  • This paper focuses on the stochastic response analysis of industrial masonry chimneys to surface blast-induced random ground motions by using a three dimensional finite element model. Underground blasts induce ground shocks on nearby structures. Depending on the distance between the explosion centre and the structure, masonry structures will be subjected to ground motions due to the surface explosions. Blast-induced random ground motions can be defined in terms of the power spectral density function and applied to each support point of the 3D finite element model of the industrial masonry system. In this paper, mainly a parametric study is conducted to estimate the effect of the blast-induced ground motions on the stochastic response of a chimney type masonry structure. With this purpose, different values of charge weight and distance from the charge centre are considered for the analyses of the chimney. The results of the study underline the remarkable effect of the surface blast-induced ground motions on the stochastic behaviour of industrial masonry type chimneys.

Charge Distribution in a capacitor observed by PEA Method (PEA법에 의한 캐패시터내 전하분포 측정)

  • Endrowednes, Kuantama;Han, Deok-Woo;Kwak, Dong-Joo;Sung, Youl-Moon
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1156-1157
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    • 2008
  • The use of the pulsed electro acoustic (PEA) method allowed us to perform the direct observations of spatio-temporal charge distributions in Electric double layer capacitors (EDLCs) based on polarizable nanoporous carbonaceous electrode. The negative charge density became the maximum, about 205 $C/m^3$ at the region where was near to collector layer in EDLCs for case $V_{DC}$ = 2.5 V, while the positively charged density became the maximum, about 61.1 $C/m^3$ at the region where it was located around the cathode layer. The PEA measurement used here is a very useful method to quantitively investigates the spatio-temporal charge distribution in EDLCs.

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