• Title/Summary/Keyword: 다층 층간분리

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Free Vibration Analysis of Multi-Delaminated Beams (다층 층간분리된 적층보의 자유진동해석)

  • 이성희;박대효;백재욱;한병기
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.14 no.4
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    • pp.469-479
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    • 2001
  • In the present study, free vibration analysis of multi-delaminated beams is performed. In order to investigate the effects of mu1ti-delaminations on the dynamic characteristics of multi-delaminated beams, the general kinematic continuity conditions are derived from the assumption of constant curvature at the multi-delamination tip. Frequency equations of multi-delaminated beams are obtained by dividing the global multi-delaminated beam into beam segments and by imposing recurrence relation from the continuity conditions un each sub-beam. The comparisons between the results of numerical analysis obtained by finite element analysis and those of present analysis give good agreement with each other. It is shown that the effects of multi-delaminations on free vibration characteristics of laminated beams could be used to detect their sizes, types and locations from the results.

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Flexural Rigidity Reduction of Multi-Delaminated Composite Beams (다층 층간분리된 복합적층보의 휨강성 감소)

  • Park, Tae-Hyo;Baek, Jae-Wook;Cho, Baik-Soon
    • Journal of Korean Society of Steel Construction
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    • v.13 no.3
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    • pp.233-244
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    • 2001
  • In this study, flexural rigidity reduction of multi-delaminated composite beams are investigated. In order to evaluate the flexural rigidity reduction. Performed theoretical analysis. In order to investigate flexural rigidity reduction about effects of delamination on composite beams, the general kinematic governing equations are derived and solved by dividing the delaminated beam and imposing the continuity conditions into each sub-beam. For condition to appear multiple delamination through the laminated composite beams, the flexural rigidity reduction are compared according to many stacking sequences and several forms for delaminations. The present study could be used to evaluate the flexural rigidity reduction of composite laminated beams on multi-delaminations.

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Free Vibrations and Buckling Loads of Axially Loaded Cross-Ply Laminated Composite Beam-Columns with Multiple Delaminations (다층간분리된 직교 적층 보-기둥의 자유진동과 좌굴하중)

  • 이성희;김형열;박기태;박대효
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.3
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    • pp.523-534
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    • 2002
  • Free vibration and buckling analysis of multi-delaminated composite beam-columns subjected to axial compressive load is performed in the present study In order to investigate the effects of multi-delaminations on the natural frequency and the elastic buckling load of multi-delaminated beam-columns, the general kinematic continuity conditions are derived from the assumption of constant slope and curvature at the multi-dclamination tip. The characteristic equation of multi-delaminated beam-column is obtained by dividing the global multi-delauunated beam-columns into segments and by imposing recurrence relation from the continuity conditions on each sub-beam-column. The natural frequency and the elastic buck)ing load of multi-delaminated beam-columns according to the incremental load of axial compression, which is limited to the maximum elastic buckling load of sound laminated beam-column, are obtained. It is found that the sizes, locations and numbers of multi-delaminations have significant effect on natural frequency and elastic buckling load, especially the latter ones.

Review on Graphene Oxide-based Nanofiltration Membrane (산화그래핀 기반 나노여과막의 최신 연구동향)

  • Kim, Dae Woo
    • Membrane Journal
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    • v.29 no.3
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    • pp.130-139
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    • 2019
  • Various two-dimensional nano materials such as graphene, zeolite, and metal-organic framework have been utilized to develop an ultra-thin high-performance membrane for water purification, gas separation, and so on. Particularly, in the case of graphene oxide, synthesis methods and thin film coating techniques have been accumulated and established since early 2000s, therefore graphene oxide has been rapidly applied to membrane field. The multi-layered graphene oxide thin film can filter molecules separately by the molecular sieving of interlayer spacing between adjacent layers, and it is also possible to separate various materials depending on the surface functional groups or the degree of interaction to intercalated materials. This review mainly focuses on the nanofiltration application of graphene oxide. The major factors affecting the separation performance of graphene oxide membrane in solvent are summarized and other technical elements required for the commercialization of graphene oxide membranes will be discussed including stability issue and fabrication method.

Characteristics of W-C-N Thin Diffusion Barrier for Cu Interconnection (Cu 금속배선을 위한 카본-질소-텅스텐 확산방지막 특성)

  • Lee, Chang-Woo
    • Journal of the Microelectronics and Packaging Society
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    • v.12 no.4 s.37
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    • pp.345-349
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    • 2005
  • Low resistive ($300{\mu}{\Omega}$-cm) W-C-N films have been deposited on tetraethylorthosilicate (TEOS) interlayer dielectric by atomic layer deposition (ALD) with $WF_6-N_2-CH_4$ gas. The exposure cycles of $N_2$ and $CH_4$ are synchronized with pulse plasma. The W-C-N films on TEOS layer follow the ALD mechanism and keep constant deposition rate of 0.2 nm/cycle from 10 to 100 cycles. As a diffusion barrier for Cu interconnection the W-C-N films maintain amorphous phase and Cu inter-diffusion is not occurred even at $800^{\circ}C$ for 30 min.

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Analysis of Magnetic Multi-layers by RBS and PIXE (후방산란법(RBS)/양성자 여기 X-선 방출법(PIXE)을 이용한 다층자성박막의 두께 및 조성 정량분석)

  • 송종한;김태곤;전기영;황정남;신윤하;김영만;장성호;김광윤
    • Journal of the Korean Magnetics Society
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    • v.11 no.6
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    • pp.272-277
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    • 2001
  • A spin valve structure of Ta/NiFe/CoFe/Cu/CoFe/Ru/CoFe/FeMn/Ta which has a synthetic antiferromagnet (CoFe/Ru/CoFe), was fabricated by using a magnetron sputtering system. The thickness and composition of magnetic free and pinned layers affect the magnetic properties such as exchange interaction strength of each layer and so on. Even though Rutherford Backscattering Spectrometry (RBS) has advantages of quantitative and non-destructive analysis, it is almost impossible to determine the thickness and composition of magnetic thin films using lBS because of its poor mass resolution for a higher atom number (Z>20). In this study, quantitative analysis of the element composition and thickness for the spin valve sample was performed by combining both Proton Induced X-ray Emission Spectrometry (PIXE), which is one of element specific analysis techniques, and grazing-exit RBS with a highly improved depth resolution and absolute quantitative analysis. For the quantitative analysis, standardization of PIXE was carried out with NiFe, CoFe, and FeMn layers, which are one of constituent layers of spin valve films. Through PIXE standardization and the aid of PHE experimental results of the spin valve sample, ire overlapped signal in a grazing-exit RBS spectrum were successfully resolved and the thickness of the Ru layer was determined with a resolution of ∼1 .

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Design and implementation of dual band power amplifier for 800MHz CDMA and PCS handset (CDMA방식의 이중대역 전력증폭기의 설계 및 제작)

  • 윤기호;유태훈;유재호;박한규
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.12
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    • pp.2674-2685
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    • 1997
  • In this paper, the design and imprlementation of dual-band power amplifier which is used as a critical part for mobile phone to be simultaneously working at a dual band, 800MHz CDAM and PCS frequency band is described. DC operating point of power FET is limited to Class-B to enable long talk time considering that the tyupical power range of CDMA phones in working is around 10 to Class-B to enable long talk time considering that the typical power range of CDMA phones in working is around 10 to 15dBm, i.e., liner range. The power amplifier which employs two GaAs FETs with good linerity at a low operating point has duplexer cuplexer circuit to separate two frequency bands at input and output stage. Electromagnetic analysis for via holes and coupling between narrow transmission lines is included to design a circuit. Moduld size of 0.96CC($22{\times}14.5{\times}3mm^3$) and maximum module current of 130mA at output power range, 10 to 15dBm are attained. The power amplifer module has achieved ACPR performance with 2 to 3dB marging from IS-95 requirement at output powers, 23.5dBm for PCS and 28dBm for 800MHz CDMA respectively.

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