• Title/Summary/Keyword: Stress currents

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The Characteristics of Silicon Oxides for Artificial Neural Network Design (인공신경회로망 설계를 위한 실리콘 산화막 특성)

  • Kang, C.S.
    • Proceedings of the IEEK Conference
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    • 2007.07a
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    • pp.475-476
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    • 2007
  • The stress induced leakage currents will affect data retention in synapse transistors and the stress current, transient current is used to estimate to fundamental limitations on oxide thicknesses. The synapse transistor made by thin silicon oxides has represented the neural states and the manipulation which gaves unipolar weights. The weight value of synapse transistor was caused by the bias conditions. Excitatory state and inhibitory state according to weighted values affected the channel current. The stress induced leakage currents affected excitatory state and inhibitory state.

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Simulation of Wave-Induced Currents by Nonlinear Mild-Slope Equation (비선형 완경사 방정식에 의한 연안류의 모의)

  • 이정렬;박찬성;한상우
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.13 no.1
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    • pp.46-55
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    • 2001
  • An approach using the nonlinear wave model in predicting wave-induced currents is presented. The model results were compared with those of the conventional model using phase-averaged radiation stress, and in addition with experimental data captured by a PIV system. As a result of comparison of wave-induced currents generated behind the surface-piercing breakwater and submerged breakwater, eddy patterns appeared to be similar each other but in general numerical solutions of both models were underestimated.

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Comparison of Wave Stresses in the Eulerian Nearshore Current Models (오일러형 해빈류 모형의 파랑응력 비교)

  • Ahn, Kyungmo;Suh, Kyung-Duck;Chun, Hwusub
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.6
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    • pp.350-362
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    • 2017
  • The Eulerian nearshore current model is more advantageous than the Lagrangian model in the way that numerical results from the Eulerian model can be directly compared with the measurements by the stationary equipment. It is because the wave mass flux is not included in the computed mass flux of Euleran nearshore current model. In addition, the Eulerian model can simulate the longshore currents with depth varying parabolic profile. However, the numerical models proposed by different researcher have different forms of the wave stress terms. For example, wave stresses in Newberger and Allen's (2007) model is constant over the depth, while those of Chun (2012) are vertically distributed. In the present study, these wave stress terms were compared against Hamilton et al.'s (2001) laboratory experiments to see the effects of different wave stress terms performed on the computation of nearshore currents.

The Study on the Trap Density in Thin Silicon Oxide Films

  • Kang, C.S.;Kim, D.J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.04b
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    • pp.43-46
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    • 2000
  • In this paper, the stress and transient currents associated with the on and off time of applied voltage were used to measure the density and distribution of high voltage stress induced traps in thin silicon oxide films. The transient currents were due to the discharging of traps generated by high stress voltage in the silicon oxides. The trap distributions were relatively uniform near both cathode and anode interface. The trap densities were dependent on the stress polarity. The stress generated trap distributions were relatively uniform the order of $10^{11}\sim10^{21}$[states/eV/$cm^2$] after a stress. The trap densities at the oxide silicon interface after high stress voltages were in the $10^{10}\sim10^{13}$[states/eV/$cm^2$]. It appear that the stress and transient current that flowed when the stress voltage were applied to the oxide was caused by carriers tunneling through the silicon oxide by the high voltage stress generated traps.

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Impact of Secondary Currents on Solute Transport in Open-Channel Flows over Smooth-Rough Bed Strips (조(粗)·세립상(細粒床)의 연속구조를 갖는 개수로 흐름에서 오염물질 수송에 대한 이차흐름 영향 분석)

  • Kang, Hyeongsik;Choi, Sung-Uk;Kim, Kyu-Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.1B
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    • pp.73-81
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    • 2009
  • This paper presents a numerical investigation of the impact of the secondary currents on solute transport in open-channel flows. The RANS model with Reynolds stress model is used for flow modeling, and the GGDH(generalized gradient diffusion hypothesis) model is used to close the scalar transport equation. Using the developed model, the impact of secondary currents on solute transport in open channel flows over smooth-rough strip is investigated. Through numerical experiments, the secondary currents are found to affect the solute spreading, leading a movement of the position of the peak concentration and a skewed distribution of solute concentration. Due to the lateral flow of secondary currents near the free surface, the concentration at the rough strip is found to be larger than that at the smooth strip bed. The solute at the rough strip is more rapidly transported than smooth bed. A magnitude analysis of the solute transport rate in scalar transport equation is also carried out to investigate the effect of secondary currents and scalar flux on the concentration distribution.

Comoutation of Currents Driven by a Steady Uniform Wind Stress on the East China Sea using a Three-dimensional Numerical Model (三次元數値모델을 使용한 東支那海의 定常均一風의 應力에 의한 海流의 算定)

  • Choi, Byung Ho
    • 한국해양학회지
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    • v.19 no.1
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    • pp.36-43
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    • 1984
  • A three-dimensional hydrodynamical numerical model of the Yellow Sea and the East China Sea is formulated having irregular coastal boundaries and non-uniform depth distribution represntative of nature. The developed model is used to derive the currents driven by a steady uniform wind stress on the Yellow Sea and the East China Sea. Numerical experiments have been performed with the model to determine the response of the shelf to stationary wind stress fields suddenly imposed on the shelf for wind directions of NW and SW winds and wind stress of 1.6dyn/$\textrm{cm}^2$. The dynamical feature of the derived circulation are presented and discussed.

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Transient trap density in thin silicon oxides

  • Kang, C.S.;Kim, D.J.;Byun, M.G.;Kim, Y.H.
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.10 no.6
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    • pp.412-417
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    • 2000
  • High electric field stressed trap distributions were investigated in the thin silicon oxide of polycrystalline silicon gate metal oxide semiconductor capacitors. The transient currents associated with the off time of stressed voltage were used to measure the density and distribution of high voltage stress induced traps. The transient currents were due to the discharging of traps generated by high stress voltage in the silicon oxides. The trap distributions were relatively uniform near both cathode and anode interface in polycrystalline silicon gate metal oxide semiconductor devices. The stress generated trap distributions were relatively uniform the order of $10^{11}$~$10^{12}$ [states/eV/$\textrm{cm}^2$] after a stress. The trap densities at the oxide silicon interface after high stress voltages were in the $10^{10}$~$10^{13}$ [states/eV/$\textrm{cm}^2$]. It was appeared that the transient current that flowed when the stress voltages were applied to the oxide was caused by carriers tunneling through the silicon oxide by the high voltage stress generated traps.

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Current Stress Minimizing Control Scheme for Power Factor Correction (PFC) Boost Pre-regulator (전류 Stress 최소화 제어설계를 응용한 PFC Boost Pre-regulator)

  • Lee, Hee-Chul;Kim, Chong-Eun;Park, Hong-Sun;Park, Ki-Bum;Moon, Gun-Woo
    • Proceedings of the KIPE Conference
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    • 2007.07a
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    • pp.353-355
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    • 2007
  • A simple technique for PFC circuit is presented using UC3854. This technique is about current peak controlling by a reference current generator. Decreased peak currents of the boost pre-regulator reduce circuit current stress and so rated currents of circuit elements are minimized. Simulation and experimental results will verify the viability of the new scheme.

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3-D Numerical Simulation of Open-Channel Flows over Smooth-Rough Bed Strips (매끄러운 하상-거친 하상의 횡방향 연속구조를 갖는 개수로 흐름의 3차원 수치모의)

  • Choi, Sung-Uk;Park, Moonhyeong;Kang, Hyeongsik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.6B
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    • pp.573-581
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    • 2006
  • This paper presents a turbulence modeling of the open-channel flows over smooth-rough bed strips. A Reynolds stress model is used for the turbulence closure. The simulated mean flow and turbulence structures are compared with the previously reported experimental data. Comparisons reveal that the developed Reynolds stress model successfully predicts the mean flow and turbulence structures of open-channel flows over smooth-rough bed strips. The computed flow vectors show cellular secondary currents, of which the upflow occurs over the smooth bed strip and the downflow over the rough bed strip. It is found that the cellular secondary currents affect the mean flow and turbulence structure. A budget analysis of the streamwise vorticity equation is also carried out to investigate the mechanism by which the secondary currents are generated.

Factors Affecting Longshore Current Profile (연안유속분포 형상에 미치는 제인자)

  • 김경호;윤영호;조재희
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.3 no.2
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    • pp.108-115
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    • 1991
  • This paper aims at the elucidation of the characteristics of longshore current profile after wave breaking. Wave breakers are always accompanied by complex turbulent process, wave energy losess occur and the mean water level also varies due to the gradient of radiation stress. These with other factors result in the development of longshore currents. Longshore currents have relations to the alongshore sand transport and to the diffusion of contaminants in nearshore region, thus the understanding and elucidation of them are very important from the engineering point of view. Using the calculated results, the factors such as lateral mixing cofficients, bed shear stress. wave angle. wave steepness and bottom slope. which are influencing the longshore current profile. are examined. Also, by comparing the results of longshore currents with the experimental data obtained by other investigators, the procedure proposed in the present study is shown to be valid.

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