• Title/Summary/Keyword: Back layer

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Enhancement of the Light Harvesting of Dye-sensitized Solar Cell by Inserting Scattering Layer (중간 광전극에 삽입된 산란층에 의한 염료감응 태양전지의 광수집 성능 향상)

  • Nam, Jung-Gyu;Kim, Bum-Sung;Lee, Jai-Sung
    • Journal of Powder Materials
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    • v.16 no.5
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    • pp.305-309
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    • 2009
  • The effect of light scattering layers (400 nm, TiO$_2$ particle) of 4 $\mu$m thickness on the dye-sensitized solar cell has been investigated with a 12 $\mu$m thickness of photo-anode (20 nm, TiO$_2$ particle). Two different structures of scattering layers (separated and back) were applied to investigate the light transmitting behaviors and solar cell properties. The light transmittance and cell efficiency significantly improved with inserting scattering layers. The back scattering layer structure had more effective transmitting behavior, but separated scattering layer (center: 2 $\mu$m, back: 2 $\mu$m) structure (9.83% of efficiency) showing higher efficiency (0.6%), short circuit current density (0.26 mA/cm$^2$) and fill factor (0.02). The inserting separating two scattering layers improved the light harvesting, and relatively thin back scattering layer (2 $\mu$m of thickness) minimized interruption of ion diffusion in liquid electrolyte.

Investigation of Device Characteristics on the Mechanical Film Stress of Contact Etch Stop Layer in Nano-Scale CMOSFET (Nano-Scale CMOSFET에서 Contact Etch Stop Layer의 Mechanical Film Stress에 대한 소자특성 분석)

  • Na, Min-Ki;Han, In-Shik;Choi, Won-Ho;Kwon, Hyuk-Min;Ji, Hee-Hwan;Park, Sung-Hyung;Lee, Ga-Won;Lee, Hi-Deok
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.45 no.4
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    • pp.57-63
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    • 2008
  • In this paper, the dependence of MOSFET performance on the channel stress is characterized in depth. The tensile and compressive stresses are applied to CMOSFET using a nitride film which is used for the contact etch stop layer (CESL). Drain current of NMOS and PMOS is increased by inducing tensile and compressive stress, respectively, due to the increased mobility as well known. In case of NMOS with tensile stress, both decrease of the back scattering ratio ($\tau_{sat}$) and increase of the thermal injection velocity ($V_{inj}$) contribute the increase of mobility. It is also shown that the decrease of the $\tau_{sat}$ is due to the decrease of the mean free path ($\lambda_O$). On the other hand, the mobility improvement of PMOS with compressive stress is analyzed to be only due to the so increased $V_{inj}$ because the back scattering ratio is increased by the compressive stress. Therefore it was confirmed that the device performance has a strong dependency on the channel back scattering of the inversion layer and thermal injection velocity at the source side and NMOS and PMOS have different dependency on them.

Application of Buffer Layers for Back Contact in CdTe Thin Film Solar Cells

  • Chun, Seungju;Kim, Soo Min;Lee, Seunghun;Yang, Gwangseok;Kim, Jihyun;Kim, Donghwan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.318.2-318.2
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    • 2014
  • The high contact resistance is still one of the major issues to be resolved in CdS/CdTe thin film solar cells. CdTe/Metal Schottky contact induced a high contact resistance in CdS/CdTe solar cells. It has been reported that the work function of CdTe thin film is more than 5.7 eV. There has not been a suitable back contact metal, because CdTe thin film has a high work function. In a few decades, some buffer layer was reported to improve a back contact problem. Buffer layers which are Te, $Sb_2Te_3$, $Cu_2Te$, ZnTe:Cu and so on was inserted between CdTe and metal electrode. A formed buffer layers made a tunnel junction. Hole carriers which was excited in CdTe film by light absorption was transported from CdTe to back metal electrode. In this report, we reported the variation of solar cell performance with different buffer layer at the back contact of CdTe thin film solar cell.

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A Characteristics of Smoke Layer Formation Affected Periodicity of Fire Plumes (Plume의 주기성이 연층형성에 미치는 영향)

  • 한용식;김명배;오광철;신현동
    • Fire Science and Engineering
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    • v.16 no.2
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    • pp.38-42
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    • 2002
  • This experiment is to understand a characteristics of smoke layer formation affected periodicity of fire plumes. The ON-OFF jet was used to constitute the oscillating flow, which was formed by a mixture of nitrogen gas with kerosene particles. The instantaneous images was obtained by digital video camera using laser sheet technique. The results were confirmed that the smoke layer in the near fire source comprise vortices which are formed by impingement from the periodicity of fire plume. The periodic impinging of plumes were thickened the smoke layer and produced the back-flow.

Classification of ECG Arrhythmia Signals Using Back-Propagation Network (역전달 신경회로망을 이용한 심전도 파형의 부정맥 분류)

  • 권오철;최진영
    • Journal of Biomedical Engineering Research
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    • v.10 no.3
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    • pp.343-350
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    • 1989
  • A new algorithm classifying ECG Arrhythmia signals using Back-propagation network is proposed. The base-line of ECG signal is detected by high pass filter and probability density function then input data are normalized for learning and classifying. In addition, ECG data are scanned to classify Arrhythmia signal which is hard to find R-wave. A two-layer perceptron with one hidden layer along with error back-propagation learning rule is utilized as an artificial neural network. The proposed algorithm shows outstanding performance under circumstances of amplitude variation, baseline wander and noise contamination.

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Comparative Study on The Numerical Simulation for The Back-Layer of The Tunnel Fire-Driven Flow with LES and RANS (터널화재유동의 역기류 해석을 위한 LES 및 RANS 결과의 비교 고찰)

  • Jang, Yong-Jun;Kim, Hag-Beom;Kim, Jin-Ho;Han, Seok-Youn
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.3
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    • pp.156-163
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    • 2009
  • In this study, comparative analysis on the back-layer phenomena in the tunnel-fire driven flow is performed using numerical simulation with LES and RANS. FDS(Fire Dynamics Simulator) code is employed to calculate the fire-driven turbulent flow for LES and Smartfire code is used for RANS. Hwang and Wargo's data of scaling tunnel fire experiment are employed to compare with the present numerical simulation. The modeled tunnel is 5.4m(L) ${\times}$ 0.4m(W) ${\times}$ 0.3m(H). Heat Release Rate (HRR) of fire is 3.3kW and ventilation-velocity is 0.33m/s in the main stream. The various grid-distributions are systematically tested with FDS code to analyze the effects of grid size. The LES method with FDS provides an improved back-layer flow behavior in comparison with the RANS (${\kappa}-{\epsilon}$) method by Smartfire. The FDS solvers, however, overpredict the velocity in the center region of flow which is caused by the defects in the tunnel-entrance turbulence strength and in the near-wall turbulent flow in FDS code.

Substrate Temperature Effects on DC Sputtered Mo thin film

  • Ahn, Heejin;Lee, Dongchan;Um, Youngho
    • Applied Science and Convergence Technology
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    • v.26 no.1
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    • pp.11-15
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    • 2017
  • To improve the adhesion of Mo thin film as a back contact material, a DC magnetron sputtering system was used to deposit in the form of a bi-layer on soda-lime glass. Films with low resistivity and good adhesion were obtained from this deposition, even though the two qualities were found be hard to obtain at the same time. The best Mo bi-layer showed a resistivity of $8.13{\times}10^{-4}{\Omega}{\cdot}cm$ at $500^{\circ}C$ and $3.0{\times}10^{-3}\;Torr$. The XRD measurements showed that the crystallites of the films were mainly oriented in the (110) direction, the FE-SEM images revealed that the resistivity of the Mo films decreased with increasing substrate temperature, which temperature reduction is accompanied by an increase of the grain size. These experimental results were analyzed using the Fuchs-Sondheimer theory. Our Mo bi-layer film with better crystallinity and lower resistivity can be suitably used as a back-contact layer for CIGS solar cells.

A neural network with local weight learning and its application to inverse kinematic robot solution (부분 학습구조의 신경회로와 로보트 역 기구학 해의 응용)

  • 이인숙;오세영
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10a
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    • pp.36-40
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    • 1990
  • Conventional back propagation learning is generally characterized by slow and rather inaccurate learning which makes it difficult to use in control applications. A new multilayer perception architecture and its learning algorithm is proposed that consists of a Kohonen front layer followed by a back propagation network. The Kohonen layer selects a subset of the hidden layer neurons for local tuning. This architecture has been tested on the inverse kinematic solution of robot manipulator while demonstrating its fast and accurate learning capabilities.

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A study on the realization of color printed material check using Error Back-Propagation rule (오류 역전파법으로구현한 컬러 인쇄물 검사에 관한 연구)

  • 한희석;이규영
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 1998.10a
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    • pp.560-567
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    • 1998
  • This paper concerned about a imputed color printed material image in camera to decrease noise and distortion by processing median filtering with input image to identical condition. Also this paper proposed the way of compares a normal printed material with an abnormal printed material color tone with trained a learning of the error back-propagation to block classification by extracting five place from identical block(3${\times}$3) of color printed material R, G, B value. As a representative algorithm of multi-layer perceptron the error Back-propagation technique used to solve complex problems. However, the Error Back-propagation is algorithm which basically used a gradient descent method which can be converged to local minimum and the Back Propagation train include problems, and that may converge in a local minimum rather than get a global minimum. The network structure appropriate for a given problem. In this paper, a good result is obtained by improve initial condition and adjust th number of hidden layer to solve the problem of real time process, learning and train.

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EFFECT OF GLASS-COATED Al PASTE ON BACK-SURFACE FIELD FORMATION IN Si SOLAR CELLS

  • HYEONDEOK JEONG;SUNG-SOO RYU
    • Archives of Metallurgy and Materials
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    • v.65 no.3
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    • pp.989-992
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    • 2020
  • In this study, glass frit was coated uniformly on the surface of Al particles instead of adding glass frit to Al powder by simple mixing to form a nano-layer. The influence of the glass-frit coating on the formation of the back-surface field and electrical characteristics of the resulting Al electrode were investigated. Microstructural observations indicated that the glass components were uniformly distributed and the back-surface field layer thickness was more uniform compared to the simply mixed sample. In addition, the sheet resistance was <10 mΩ/□, much lower than the 23 mΩ/□ of the simply mixed Al electrode.