• 제목/요약/키워드: heterogeneous materials

검색결과 446건 처리시간 0.027초

AZ31 마그네슘합금 레이저 용접부의 미세조직 및 미소경도의 분포에 관한 연구 (A study on the microstructure and micro-hardenss distribution in laser welded AZ31 magnesium alloy)

  • 최영환;이목영;최시훈
    • 한국레이저가공학회지
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    • 제15권3호
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    • pp.11-15
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    • 2012
  • The laser weld of AZ31 magnesium alloy was characterized with OM, EBSD and micros vickers hardness tester in experiment. EBSD analysis and micro-hardness measurements were carried out at the three regions (Equiaxed Zone, Columnar Dendrite Zone, Base Metal) of the welded AZ31Mg alloy sheets. The magnesium alloy show the rectangular shape bead in laser weld. EBSD analysis revealed that the three regions show the heterogeneous distribution of grain size and microtexture. Micro-hardness measurement also revealed that the heterogeneous distribution of microstructure contributed to the heterogeneous micro-hardness distribution in the three regions.

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레이저 용접에 의한 이종재료의 잔류응력과 굽힘 특성 분석 (The Analysis of the Residual Stress and Bending Characteristics on the Heterogeneous Materials by Laser Welding)

  • 오세헌;민택기
    • Journal of Welding and Joining
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    • 제22권3호
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    • pp.45-49
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    • 2004
  • Generally, it is used the compensation spring to compensate the inaccuracy of screen image induced by thermal deformation in CRT monitor. Its mechanism is hi-metallic system made of heterogeneous metals and these springs are bonded by laser welding. But laser welding induces a non-uniform temperature distribution, and residual stress is yielded locally by these temperature deviation. Therefore, this study measures the curvature constant to assess functions of the compensation spring of shadow mask with respect to increment temperature and estimates the effect of residual stress on the performance of tri-metal used to compensation spring.

Performance Study of Composite Air Filters Using Heterogeneous Fibers

  • Lee, Ji Soo;Oh, Yuree;Kim, Heejin;Park, Hyun-Seol;Yoon, Sam S.;Lee, Min Wook
    • Composites Research
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    • 제35권3호
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    • pp.216-221
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    • 2022
  • Recently, the worldwide demand for disposable masks has increased due to COVID-19 infections and severe air pollution. Personal masks should reduce breathe resistance while maintaining filtering performance. In this study, a solution blowing process is used to produce composite nanofiber filters to co-spin two polymers at once. The manufacture process of the various fiber diameter filter was designed, and the filtration performance and differential pressure of the prepared filter was investigated. Poly vinylidene fluoride-hexafluoropropylene (PVDF-HFP) and Polylactic acid (PLA) fibers were chosen to be entangled together in a layer with a diameter of 1.05 ㎛ and 0.33 ㎛. Composite nanofilters showed up to 87% filtration efficiency and 32 Pa differential pressure.

3-D Hetero-Integration Technologies for Multifunctional Convergence Systems

  • 이강욱
    • 마이크로전자및패키징학회지
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    • 제22권2호
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    • pp.11-19
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    • 2015
  • Since CMOS device scaling has stalled, three-dimensional (3-D) integration allows extending Moore's law to ever high density, higher functionality, higher performance, and more diversed materials and devices to be integrated with lower cost. 3-D integration has many benefits such as increased multi-functionality, increased performance, increased data bandwidth, reduced power, small form factor, reduced packaging volume, because it vertically stacks multiple materials, technologies, and functional components such as processor, memory, sensors, logic, analog, and power ICs into one stacked chip. Anticipated applications start with memory, handheld devices, and high-performance computers and especially extend to multifunctional convengence systems such as cloud networking for internet of things, exascale computing for big data server, electrical vehicle system for future automotive, radioactivity safety system, energy harvesting system and, wireless implantable medical system by flexible heterogeneous integrations involving CMOS, MEMS, sensors and photonic circuits. However, heterogeneous integration of different functional devices has many technical challenges owing to various types of size, thickness, and substrate of different functional devices, because they were fabricated by different technologies. This paper describes new 3-D heterogeneous integration technologies of chip self-assembling stacking and 3-D heterogeneous opto-electronics integration, backside TSV fabrication developed by Tohoku University for multifunctional convergence systems. The paper introduce a high speed sensing, highly parallel processing image sensor system comprising a 3-D stacked image sensor with extremely fast signal sensing and processing speed and a 3-D stacked microprocessor with a self-test and self-repair function for autonomous driving assist fabricated by 3-D heterogeneous integration technologies.

Novel Bi2S3/TiO2 Heterogeneous Catalyst: Photocatalytic Mechanism for Decolorization of Texbrite Dye and Evaluation of Oxygen Species

  • Zhu, Lei;Oh, Won-Chun
    • 한국세라믹학회지
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    • 제53권1호
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    • pp.56-62
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    • 2016
  • A heterogeneous $Bi_2S_3/TiO_2$ composite catalyst was synthesized via a green ultrasonic-assisted method and characterized by XRD, SEM, EDX, TEM analysis. The results clearly show that the $TiO_2$ particles were homogenously coated with $Bi_2S_3$ particles, indicating that $Bi_2S_3$ particle agglomeration was effectively inhibited after the introduction of anatase $TiO_2$. The Texbrite BA-L (TBA) degradation rate constant for $Bi_2S_3/TiO_2$ composites reached $8.27{\times}10^{-3}min^{-1}$ under visible light, much higher than the corresponding value of $1.04{\times}10^{-3}min^{-1}$ for $TiO_2$. The quantities of generated hydroxyl radicals can be analyzed by DPCI degradation, which shows that under visible light irradiation, more electron-hole pairs can be generated. Finally, the possible mechanism for the generation of reactive oxygen species under visible-light irradiation was proposed as well. Our result shows the significant potential of $Bi_2S_3$-semiconductor-based $TiO_2$ hybrid materials as catalysts under visible light for the degradation of industry dye effluent substances.

패션윈도우 디스플레이에 나타난 데페이즈망(Depaysement) - 미국, 프랑스, 일본 백화점을 중심으로 - (Depaysement expressed in Fashion Window Display - Focused on Department stores in US, France and Japan -)

  • 허승연;이연희
    • 복식
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    • 제64권3호
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    • pp.1-12
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    • 2014
  • The purpose of this study is to investigate the Depaysement techniques in a new perspective, which are applicable to fashion window display. It was investigated by studying the case of Depaysement expressed in contemporary fashion window display. The analysis object of this study was limited to window displays shown at the world's most famous department stores in the last five years. The data was collected through related specialty publications and each department store's websites. The framework for analysis of this study is established by relevant precedent studies. The results of this study were drawn form comparative quantitative analysis from an expert group. Through the study, the characteristics of Depaysement in the contemporary fashion window display were classified into 'Change of forms and materials', 'Heterogeneous combination of objects', 'Location change of an object', 'Conversion of recognition on an object' and 'Change of spatial awareness'. The expression approaches were 'Change of scale', 'Change of materials', 'Combination of heterogeneous objects', 'Heterogeneous combination', 'Arrangement of object in a strange space', 'Change of display method', 'Overlapped object', 'Paradoxical image', 'Variable awareness of boundary' and 'Reorganization of interior space and change of materials'.

SBA-15 Supported Fe, Ni, Fe-Ni Bimetallic Catalysts for Wet Oxidation of Bisphenol-A

  • Mayani, Suranjana V.;Mayani, Vishal J.;Kim, Sang Wook
    • Bulletin of the Korean Chemical Society
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    • 제35권12호
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    • pp.3535-3541
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    • 2014
  • Bisphenol A is considered as pollutant, because it is toxic and hazardous to living organisms even at very low concentrations. Biological oxidation used for removing this organic from waste water is not suitable and consequently application of catalytic wet oxidation has been considered as one of the best options for treating bisphenol A. We have developed Fe/SBA-15, Ni/SBA-15 and Fe-Ni/SBA-15 as heterogeneous catalysts using the advanced impregnation method for oxidation of bisphenol A in water. The catalysts were characterized with physico-chemical characterization methods such as, powder X-ray diffraction (PXRD), FT-IR measurements, N2 adsorption-desorption isotherm, thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. This work illustrates activity of the catalysts for heterogeneous catalytic degradation reaction revealed with excellent conversion and recyclability. The degradation products identified were not persistent pollutants. GC-MS analysis identified the products: 2,4-hexadienedioic acid, 2,4-pentadienic acid and isopropanol or acetic acid. The leachability study indicated that the catalysts release very little metals to water. Therefore, the possibility of water contamination through metal leaching was almost negligible.