• Title/Summary/Keyword: 다중벽 탄소 나노 튜브

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Flowability and Strength of Cement Composites with Different Dosages of Multi-Walled CNTs (다중벽 탄소나노튜브의 혼입량에 따른 시멘트 복합체의 유동성 및 강도 변화)

  • Ha, Sung-Jin;Kang, Su-Tae
    • Journal of the Korea Concrete Institute
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    • v.28 no.1
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    • pp.67-74
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    • 2016
  • With several different dosages of multi-walled CNTs which was 0.1, 0.3, and 0.5% of the weight of binder, the fluidity in fresh CNT cement composites, as well as the strength and strength development with age of the hardened composites were investigated in this experimental study. The experimental results from flow test indicated that the increase in the dosage of CNTs badly impacted on the workability of fresh composites, and the results from rheological measurements presented the decrease in plastic viscosity and the increase in yield stress according to the amount of CNTs. In addition, the thixotrophy in the flow curve obtained from the rheology test was observed more noticeably in the composites with higher dosage of CNTs. With the experiments on the strength properties, the improvement of both compressive and tensile strengths with the increase of CNTs dosage could be obtained. Moreover, early strength development by adding CNTs was found when it was compared with plain cementious matrix without CNT.

A Study on the Relationship between Surface Condition and Critical Heat Flux in Heat Exchanger (열교환기 표면상태와 CHF의 상관관계에 대한 연구)

  • Kim, Woo-Joong;Kim, Nam-Jin
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.16 no.2
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    • pp.1-6
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    • 2020
  • This work experimentally explored the influence of nano-fouling on CHF, flow boiling heat transfer coefficient, contact angle, and surface roughness. In this study, the flow velocity conditions are established at 0.5, 1.0, and 1.5 m/s. Also, the nanoparticles of oxidized MWCNT were deposited on a heat transfer surface for 0, 120, 180, and 240 sec. As the results, it was found that CHF and superheated temperature were increased in case of nano fouling on the heat transfer surface in oxidized MWCNT fluid. Also, the contact angle and surface roughness decreased when flow velocity and nano coating increased.

Pressure sensing of air flow using multi-walled carbon nanotubes (다중벽 탄소 나노튜브를 이용한 유동 압력 검출)

  • Song, Jin-Won;Lee, Jong-Hong;Lee, Eung-Sug;Han, Chang-Soo
    • Journal of Sensor Science and Technology
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    • v.16 no.5
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    • pp.377-383
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    • 2007
  • We describe the fabrication and characterization of a doubly clamped multi-walled carbon nanotube (MWNT). The device was assembled by an application of electric field in solution. The MWNT was clamped on end of metal trench electrodes in solution and deposited with additional platinum (Pt) on edge of electrode for firmly suspending the MWNT by focused ion beam (FIB). The MWNTs range of diameter and length were 100 to 150 nm and 1.5 to $2{\mu}m$, respectively. Electrical characteristics of fabricated devices were measured by I-V curve and impedance analysis. The mechanical deformation was observed by resistivity in high air pressure. Resonant frequency around 6.8 MHz was detected and resistivity was linearly varied according to the magnitude of air pressure. This device could have potential applications in nanoelectronics and various sensors.