• 한국소음진동공학회논문집
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• 제20권4호
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• pp.390-396
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• 2010

Resonant frequencies and the associated vibrational modes of multiwall carbon nanotubes are studied in this paper. The analysis is based on a multiple-elastic beam model, considering intertube radial displacements and the related internal degrees of freedom. Especially, van der Waals interaction is modified considering both all interaction between each layers in multi-wall carbon nanotubes and curvature effect. The results show that modified van der Waals interaction could significantly affect the natural frequencies of multi-walled carbon nanotubes. In particular, non-coaxial intertube resonance will be excited at the higher resonant frequencies of multiwall carbon nanotubes.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.859-862
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• 2003

Well-aligned multiwall carbon nanotubes (MWCNTs) were prepared at low temperature of 400 $^{\circ}C$ by utilizing a radio frequency plasma-enhanced chemical vapor deposition (rf-PECVD) system. The MWCNTs were treated by an external rf plasma source and an ultra-violet laser in order to modify structural defect of carbon nanotube and to ablate possible contamination on carbon nanotube surface. Structural properties of carbon nanotubes were investigated by using a scanning electron microscopy (SEM), Raman spectroscopy, Fourier transformer Infrared spectroscopy (FTIR) and transmission electron microscope (TEM). In addition, the emission properties of the MWNTs were measured for the application of field emission display (FED) in near future. Various post treatments were found to improve the field emission property of carbon nanotubes.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2193-2196
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• 2014

• 한국표면공학회지
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• 제48권6호
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• pp.309-314
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• 2015

Multiwall carbon nanotubes are synthesized by using VLS mechanism for the application to $H_2$ gas sensor. MWCNT is not suitable for hydrogen gas sensor due to its low response to the gas. To enhance the gas sensing performance, multiwall carbon nanotubes are coated with $TiO_2$ nanoparticles. Scanning electron microscopy and Transmission electron microscopy showed that the synthesized MWCNT were well dispersed with the diameter and wall thickness of approximately 10-30nm and 5nm, respectively. The MWCNT sensor showed the sensitivities of 1.33-9.5% for the $H_2$ concentration of 100-5000ppm at room temperature. These sensitivities are significantly improved to 6.64-46.65% by coating $TiO_2$ nanoparticles to the MWCNT sensor. The mechanisms of $H_2$ gas sensing improvement of the MWCNT sensor coated with $TiO_2$ nanoparticles are discussed.

• Carbon letters
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• 제3권3호
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• pp.142-145
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• 2002

Multiwall carbon nanotubes (MWNT) were produced using the arc-discharge graphite evaporation technique. Composite films were developed using MWNT dispersed in polystirol polymer. In the present work, various properties of the polymeric thin film containing carbon nanotubes were investigated by optical absorption, electrical resistivity and the same have been discussed.

• Carbon letters
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• 제21권
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• pp.116-121
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• 2017

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.219-224
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• 2012

In this paper, vibration and flow-induced flutter instability analysis of cantilever multiwall carbon nanotubes conveying fluid and modelled as a thin-walled beam is investigated. Non-classical effects of transverse shear and rotary inertia are incorporated in this study. The governing equations and the associated boundary conditions are derived through Hamilton's principle. Numerical analysis is performed by using extend Galerkin method which enables us to obtain more exact solutions compared with conventional Galerkin method. Cantilevered carbon nanotubes are damped with decaying amplitude for flow velocity below a certain critical value, however, beyond this critical flow velocity, flutter instability may occur. Variations of critical flow velocity with both radius ratio and length of carbon nanotubes are investigated and pertinent conclusion is outlined.

• Applied Microscopy
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• 제46권4호
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• pp.244-252
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• 2016

This paper describes a new design of carbon nanotube tip. $Nanocly^{TM}$ NC 7000 Thin Multiwall Carbon Nanotubes of carbon purity (90%) and average diameter tube 9.5 nm with a high aspect-ratio (>150) were used. These tips were manufactured by employing a drawing technique using a glass puller. The glass microemitters with internal carbon nanotubes show a switch-on effect to a high current level (1 to $20{\mu}A$). A field electron microscope with a tip (cathode)-screen (anode) separation at ~10 mm was used to characterize the electron emitters. The system was evacuated down to a base pressure of ${\sim}10^{-9}$ mbar when baked at up to ${\sim}200^{\circ}C$ overnight. This allowed measurements of typical Field Electron Emission characteristics; namely the current-voltage (I-V) characteristics and the emission images on a conductive phosphorus screen (the anode). Fowler-Nordheim plots of the current-voltage characteristics show current switch-on for each of these emitters.

• Advances in nano research
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• 제3권1호
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• pp.1-11
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• 2015

Thin film ethanol sensors made from ${\alpha}-Fe_2O_3$ decorated with multiwall carbon nanotubes(MWCNTs) were manufactured by the electron beam deposition method. The morphology of the decorated ${\alpha}-Fe_2O_3$/MWCNTs (25:1 weight ratios) nanocomposite powder was investigated using the scanning electron microscopy and X-ray diffraction techniques. The thickness of thin films has been determined from ellipsometric measurements. The response of manufactured sensors was investigated at different temperatures of the sensor work body and concentration of gas vapors. Good response of prepared sensors to ethanol vapors already at work body temperature of $150^{\circ}C$ was shown.

• 폴리머
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• 제38권3호
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• pp.378-385
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• 2014

초음파를 이용한 수중 반응을 통하여 친수성 고분자인 poly(vinyl alcohol) (PVA)를 다중벽 탄소나노튜브 표면에 개질하였다. 초음파 인가 시 PVA는 라디칼을 지닌 상태로 절단되며 탄소나노튜브는 일반적으로 라디칼 스캐빈저 역할을 하므로 생성된 PVA 라디칼과 반응하여 PVA 사슬이 탄소나노튜브 표면에 그래프트 된다. PVA의 그래프트 반응을 조절하기 위하여 초음파 인가 조건을 300과 500 W로 선택하였으며, 인가 시간은 최대 50분으로 하였다. 탄소나노튜브 표면에 그래프트된 PVA는 FTIR, TGA, SEM, 및 TEM을 통하여 분석하였다. 또한 PVA로 개질된 탄소나노튜브의 분산안정성을 분석하였다. 그래프트된 PVA의 양은 초음파의 인가 출력과 인가 시간에 비례하여 증가하였으며, PVA로 개질된 탄소나노튜브는 물 속에서 매우 안정적인 분산성을 보였다. 이는 복잡한 화학반응 과정없이 초음파를 이용하면 탄소나노튜브를 고분자로 간단히 개질할 수 있음을 보여준다.