• Title/Summary/Keyword: 단일 drain 해석

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The Applicability of Numerical Analysis Technique to The Soft Clayey Foundation Improved by Sand Drain (Sand Drain 지반에 대한 변형해석법의 적용성)

  • Lee, Jean-Soo;Lee, Moon-Soo;Jang, Chul
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.40 no.1
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    • pp.96-105
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    • 1998
  • Soil properties, drain conditions and numerical analysis technique have great influence upon consolidation behavior. In relevant to the above described fact, this paper aims to examining the applicability of prediction model of consolidation as well as deformation characteristics for soft clayey foundation improved by sand drain. A case study for actual foundation of Kwangyang steel works was performed. Single drain consolidation model proposed by Hansbo and Biot's consolidation theory coupled with modified Cam-clay model developed during the research were employed for the FEM numerical analysis of the foundation. Both smear effect and drain capacity were taken into account for the analysis. Finally the applicability of the newly developed technique to the behavior of foundation composed of soft clay proved satisfactory.

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Numerical Study on Draining from Cylindrical Tank Using Stepped Drain Port (계단형 배수구를 가진 원통 용기에서의 배수 과정에 관한 수치해석 연구)

  • Son, Jong Hyeon;Park, Il Seouk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.12
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    • pp.1043-1050
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    • 2014
  • An air-core vortex is generated during draining after stirring a rotating cylindrical tank or after filling it with water. The formation of the air-core vortex and the time of its formation are dependent on drain conditions such as the dimensions of the tank, the initial rotation or stirring speed, and the shape of the drain port. In this study, a draining process using a two-stage drain port was numerically investigated. The length and radius of the first drain stage located in the lower part of the drain port were kept constant, whereas the radius of the second drain stage was varied for simulating the draining process. The simulation was conducted by considering an axisymmetric swirling flow for all cases. The declining water level was monitored by an interface capturing method. Further, the effects of the radius of the second drain stage on the time of formation of the air-core vortex and the internal flow structure were investigated.

A Study on the Current-Voltage Characteristics of a Short-Channel GaAs MESFET Using a New Linearly Graded Depletion Edge Approximation (선형 공핍층 근사를 사용한 단채널 GaAs MESFET의 전류 전압 특성 연구)

  • 박정욱;김재인;서정하
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.37 no.2
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    • pp.6-11
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    • 2000
  • In this paper, suggesting a new linearly -graded depletion edge approximation, the current-voltage characteristics of an n-type short-channel GaAs MESFET device has been analyzed by solving the two dimensional Poisson's equation in the depletion region. In this model, the expressions for the threshold voltage, the source and the drain ohmic resistance, and the drain current were derived. As a result, typical Early effect of a short channel device was shown and the ohmic voltage drop by source and drain contact resistances could be explained. Furthermore our model could analyze both the short-channel device and the long-channel device in a unified manner.

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Design on Optimum Control of Subthreshold Current for Double Gate MOSFET (DGMOSFET에서 최적의 서브문턱전류제어를 위한 설계)

  • Jung, Hak-Kee;Na, Young-Il;Lee, Jong-In
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.887-890
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    • 2005
  • The double gate(DG) MOSFET is a promising candidate to further extend the CMOS scaling and provide better control of short channel effect(SCE). DGMOSFETs, having ultra thin updoped Si channel for SCEs control, are being validated for sub-20nm scaling, A channel effects such as the subthreshold swing(SS), and the threshold voltage roll-off(${\Delta}V_{th}$). The propsed model includes the effects of thermionic emission and quantum tunneling of carriers through the source-drain barrier. The proposed model is used to design contours for gate length, channel thickness, and gate oxide thickness.

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Analysis of Drain Induced Barrier Lowering for Double Gate MOSFET According to Channel Doping Concentration (채널도핑강도에 대한 이중게이트 MOSFET의 DIBL분석)

  • Jung, Hak-Kee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.3
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    • pp.579-584
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    • 2012
  • In this paper, drain induced barrier lowering(DIBL) has been analyzed as one of short channel effects occurred in double gate(DG) MOSFET. The DIBL is very important short channel effects as phenomenon that barrier height becomes lower since drain voltage influences on potential barrier of source in short channel. The analytical potential distribution of Poisson equation, validated in previous papers, has been used to analyze DIBL. Since Gaussian function been used as carrier distribution for solving Poisson's equation to obtain analytical solution of potential distribution, we expect our results using this model agree with experimental results. The change of DIBL has been investigated for device parameters such as channel thickness, oxide thickness and channel doping concentration.

Analysis of Drain Induced Barrier Lowering for Double Gate MOSFET According to Channel Doping Intensity (채널도핑강도에 대한 DGMOSFET의 DIBL분석)

  • Jung, Hak-Kee
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2011.10a
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    • pp.888-891
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    • 2011
  • In this paper, drain induced barrier lowering(DIBL) has been analyzed as one of short channel effects occurred in double gate(DG) MOSFET. The DIBL is very important short channel effects as phenomenon that barrier height becomes lower since drain voltage influences on potential barrier of source in short channel. The analytical potential distribution of Poisson equation, validated in previous papers, has been used to analyze DIBL. Since Gaussian function been used as carrier distribution for solving Poisson's equation to obtain analytical solution of potential distribution, we expect our results using this model agree with experimental results. The change of DIBL has been investigated for device parameters such as channel thickness, oxide thickness and channel doping intensity.

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Stiffness and Strength of Composite Beams in Steel Building Structures Under Lateral Loading (횡하중을 받는 철골구조물에서 합성보의 강성과 강도)

  • 이승준
    • Computational Structural Engineering
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    • v.2 no.4
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    • pp.79-88
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    • 1989
  • The behavior of composite beams in steel building structures subjected to lateral loading is studied. Mathematical models for the stiffness of composite beams and the strength at the connections, which are dependent on details of the connections are developed based on the previous experimental results and the results from numerical analyses. Analytical models for the skeleton and hysteresis curves of cantilever composite beams are also presented. A single component model for the composite beam, consisting of elastic beam and the end springs at which all the inelstic deformations within a member are lumped, is implemented into the computer program, DRAIN-2D. And a comparison of analytical results is made with the experimental results.

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Numerical Analysis of Soil Vapour Extraction Remediation System using Prefabricated Vertical Drain (토목섬유 연직배수재를 활용한 토양증기추출복원시스템의 수치해석)

  • Shin, Eun-Chul;Park, Jeong-Jun;Lee, Kyu-Woong
    • Journal of the Korean Geosynthetics Society
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    • v.7 no.4
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    • pp.1-8
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    • 2008
  • Soil vapor extraction (SVE) is an effective and cost efficient method of removing volatile organic compounds (VOCs) and petroleum hydrocarbons from unsaturated soils. However, soil vapor extraction becomes ineffective in soils with low gas permeability, for example soils with air permeabilities less than 1 Darcy. The aim of this study is to investigate numerically the performance of a prefabricated vertical drain (PVD) as a SVE well, and the pattern of the induced air flow. A validated numerical model for a single PVD extraction well is developed based on the result of a well-designed laboratory model test. The validity of the simple analytical approach to determine air permeability based on the results of model tests is also discussed.

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Comparison on the Performance of Soil Improvement in Thick Soft Ground Using Single-Core and Double-Core PBD (단일 및 이중 코어 PBD에 의한 대심도 연약지반 개량 효과에 관한 비교연구)

  • Yang, Jeong-Hun;Hong, Sung-Jin;Kim, Hyung-Sub;Lee, Woo-Jin;Choi, Hang-Seok
    • Journal of the Korean Geotechnical Society
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    • v.25 no.8
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    • pp.33-45
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    • 2009
  • The conventional single-core PBDs have been widely used in order to accelerate consolidation settlement of soft grounds. When using the single-core PBD in a thick clay deposit, a delay of consolidation may occur due to high confining pressure in the thick deposit and necking of drains. This study is to compare the performances of soil improvement by the single-core and double-core PBD installed at a site in Busan New Port which exhibits approximately a 40m-thick clay layer. An in-situ test program was performed at the test site where a set of the double-core PBDs and single-core PBDs were installed to compare the efficiency of each drain. In addition, the discharge capacity of each PBD has been measured using the modified Delft Test. A series of laboratory tests for estimating in-situ soil properties have also been performed in order to obtain input parameters for a numerical program ILLICON. The discharge capacity of the double-core PBD is higher than that of the single-core PBD in the modified Delft Test. However it is observed from the comparative in-situ test and numerical analysis that there is no difference in the performance of ground improvement between the two drain systems. This discrepancy comes from the fact that the amount of water released during consolidation in most common field conditions is much smaller than the capacity of even the single core PBD. And thus, considering actual field conditions, it can be concluded that the single-core PBD has enough discharge capacity even in the thick clay deposit such as this test site.

Analytical Modeling for Short-Channel MOSFET I-V Characteristice Using a Linearly-Graded Depletion Edge Approximation (공핍층 폭의 선형 변화를 가정한 단채널 MOSFET I-V 특성의 해석적 모형화)

  • 심재훈;임행삼;박봉임;여정하
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.4
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    • pp.77-85
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    • 1999
  • By assuming a linearly graded depletion edge approximation in the intrinsic MOS region and by taking into account the mobility variation dependent on both lateral and vertical fields, a physics-based analytical model for a short-channel(n-channel) MOSFET is suggested. Derived expressions for the threshold voltage and the drain current of typical MOSFET is structures could be used in a unified manner for all operating range. The threshold voltage was calculated by changing following variables : channel length, drain-source voltage, source-substrate voltage, p-substrate doping level, and oxide thickness. It is shown that the threshold voltage decreases almost exponentially as the channel length decreases. In addition, the short-channel threshold voltage roll-off, the channel length modulation and the electron mobility degradation can be derived within a satisfactory accuracy.

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