• Journal of Sensor Science and Technology
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• v.13 no.4
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• pp.292-297
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• 2004

Carbon nanotubes (CNT) were synthesized by arc-discharge method. To fabricate CNT sensor, CNT powder was dispersed in ${\alpha}$-Terpinol($C_{10}H_{17}OH$) solution. The CNT tilms were fabricated by screen printing method on the interdigitated Pt/Pd alloy electrode. The microstructure of CNT film was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In order to investigate the gas sensing characteristics of the film, the CNT film was experimented to measure NO response and recovery time. The CNT sensor with a heater was compared to that without a heater. And this sensor shows better reproductibility and faster recovery time than another CNT sensors. We suggest the possibility to utilize a CNT as new sensing materials for environmental monitoring.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1081-1086
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• 2005

Dynamic behavior of carbon nanotubes (CNTs) in an electric field is directly observed by in-situ transmission electron microscopy (TEM). The CNT field emitters examined by in-situ TEM are multiwalled, double-walled and single walled CNTs. Threshold fields for electron emission and sustainable emission currents depending on the structure of CNTs are presented, and degradation mechanism of the CNT field emitters is discussed. In addition to the microscopy studies on individual CNTs, our recent development in surface treatment of CNT layers grown by chemical vapor deposition, which brings about high density of emission current and high uniformity, is also presented.

• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.129-139
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• 2020

In this piece of work, carbon nanotubes motion equations are framed by Kelvin's method. Employment of the Kelvin's method procedure gives birth to the tube frequency equation. It is also exhibited that the effect of frequencies is investigated by varying the different index of polynomial function. By using volume fraction for power law index, the fundamental natural frequency spectra for two forms of single-walled carbon nanotubes are calculated. The influence of frequencies against length-to-diameter ratios with varying power law index are investigated in detail for these tubes. Throughout the computation, it is observed that the frequency behavior for the boundary conditions follow as; clamped-clamped, simply supported-simply supported and these frequency curves are higher than that of clamped-free curves. Computer software MATLAB is utilized for the frequencies of single-walled carbon nanotubes.

• Korean Journal of Materials Research
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• v.14 no.4
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• pp.276-280
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• 2004

Carbon nanotubes(CNT) were synthesized by arc-discharge method. To fabricate CNT sensor, CNT powder was dispersed in $\alpha$-Terpinol($C_{10}$ $H_{17}$OH) solution. The CNT films were fabricated by screen printing on the interdigitated Pt/Pd alloy electrode. The microstructure of CNT film were observed by scanning electron microscopy (SEM). In order to investigate the gas sensing characteristics of the film, the CNT film was experimented to measure NH$_3$ response and recovery time. And this sensor shows better reproductibility and faster recovery time than another CNT sensors. We suggest the possibility to utilize a CNT as new sensing materials for environmental monitoring.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.7
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• pp.359-363
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• 2006

Single-walled carbon nanotubes (SWCNTs) with few defects and very small amount of amorphous carbon coating have been synthesized by catalytic decomposition of methane in $H_2$ over well-dispersed metal particles supported on MgO. The yield of SWCNTs was estimated to be 88.5% and the purities of SWCNTs thus obtained were more than 90%. Peak of the radial breathing mode in the Raman spectrum demonstrated that the diameters of synthesized CNTs are in the range 0.4-2.0 nm. Our results also indicated that MgO support materials are useful to a large-scale synthesis of high-quality SWCNTs. Increasing temperature could remarkably increase the yield and also improve the quality of SWCNTs from catalytic decomposition of methane. The morphologies and microstructures of the synthesized carbon materials were characterized by scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray diffraction (XRD).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.131-136
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• 2011

Many researchers are recently studying about Electroactive polymer(EAP). But it has a physical limitation, because of property of material. Carbon nanotube(CNT) is known as the promising material which has excellent electro-mechanical characteristics and is mostly defect-free. It is expected that a successful synthesis of CNT and Nafion known as a primary material for IPMC would make a great improvement on its electro-mechanic feature. This study focuses on the method of synthesis of CNT with Nafion which improves electro-mechanical characteristic. To come up with mechanical dispersion with Nafion and Isopropyl Alcohol(IPA), we dispersed Single-walled carbon nanotubes(SWCNTs). For a uniformly layer of CNT, we used a spray gun on a hot plate by a simplified method. We fabricated a disperse SWCNT/Nafion composite uniformly. Through the use of the E-beam evaporator to form an uniform electrode layer, we consummated the IPMC actuator. This result shows improving 1.5 times mechanical properties about driving force in IPMC.

• Transactions on Electrical and Electronic Materials
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• v.9 no.4
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• pp.169-172
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• 2008

We attempted to fabricate carbon nanotube field effect transistor (CNT-FET) using single walled carbon nanotube(SWNT) on the heavily doped Si substrate used as a bottom gate, source and drain electrode were fabricated bye-beam lithography on the 500 nm thick $SiO_2$ gate dielectric layer. We investigated electrical and physical properties of this CNT-FET using Scanning Probe Microscope(SPM) and conventional method based on tungsten probe tip technique. The gate length of CNT-FET was 600 nm and the diameter of identified SWNT was about 4 nm. We could observed gating effect and typical p-MOS property from the obtained $V_G-I_{DS}$ curve. The threshold voltage of CNT-FET is about -4.6V and transconductance is 47 nS. In the physical aspect, we could identified SWNT with phase mode of SPM which detecting phase shift by force gradient between cantilever tip and sample surface.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.201-201
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• 2012

Using materials with high thermal conductivity is a matter of great concern in the field of thermal management. In this study, we present our experimental results on an important physical property of carbon nanotube (CNT) films, two-dimensional thermal conductivity obtained by using an optical method based on Raman spectroscopy. We prepared four kinds of CNT films to investigate the effect of CNT type on heat spreading performance of films. This first comparative study using the optical method shows that the arc-discharge single-walled carbon nanotubes yield the best heat spreading film. And we observed thermal conductivity values of CNT films with various transmittances and found that the Raman method works as long as the sample is a transparent film. This study provides useful information on characterization of thermal conduction in transparent CNT films and could be an important step toward high-performance carbon-based heat spreading films.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.363.2-363.2
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• 2016

Stretchable strain sensors are becoming essential in diverse future applications, such as human motion detection, soft robotics, and various biomedical devices. One of the well-known approaches for fabricating stretchable strain sensors is to embed conductive nanomaterials such as metal nanowires/nanoparticles, graphene, conducting polymer and carbon nanotubes (CNTs) within an elastomeric substrate. Among various conducting nanomaterials, CNTs have been considered as important and promising candidate materials for stretchable strain sensors owing to their high electrical conductivity and excellent mechanical properties. In the past decades, CNT-based strain sensors with high stretchability or sensitivity have been developed. However, CNT-based strain sensors which show both high stretchability and sensitivity have not been reported. Herein, highly stretchable and sensitive strain sensors were fabricated by integrating single-walled carbon nanotubes (SWNTs) and nylon textiles via vacuum-assisted spray-layer-by-layer process. Our strain sensors had high sensitivity with 100 % tensile strain (gauge factor ~ 100). Cyclic tests confirmed that our strain sensors showed very robust and reliable characteristic. Moreover, our SWNTs-based strain sensors were easily and successfully integrated on human finger and knee to detect bending and walking motion. Our approach presented here might be route to preparing highly stretchable and sensitive strain sensors with providing new opportunity to realize practical wearable devices.

• Steel and Composite Structures
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• v.24 no.6
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• pp.711-726
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• 2017

In the present work, by considering the agglomeration effect of single-walled carbon nanotubes, free vibration characteristics of functionally graded (FG) nanocomposite sandwich plates resting on Pasternak foundation are presented. The volume fractions of randomly oriented agglomerated single-walled carbon nanotubes (SWCNTs) are assumed to be graded in the thickness direction. To determine the effect of CNT agglomeration on the elastic properties of CNT-reinforced composites, a two-parameter micromechanical model of agglomeration is employed. In this research work, an equivalent continuum model based on the Eshelby-Mori-Tanaka approach is employed to estimate the effective constitutive law of the elastic isotropic medium (matrix) with oriented straight CNTs. The 2-D generalized differential quadrature method (GDQM) as an efficient and accurate numerical tool is used to discretize the equations of motion and to implement the various boundary conditions. The proposed rectangular plates have two opposite edges simply supported, while all possible combinations of free, simply supported and clamped boundary conditions are applied to the other two edges. The benefit of using the considered power-law distribution is to illustrate and present useful results arising from symmetric and asymmetric profiles. The effects of two-parameter elastic foundation modulus, geometrical and material parameters together with the boundary conditions on the frequency parameters of the laminated FG nanocomposite plates are investigated. It is shown that the natural frequencies of structure are seriously affected by the influence of CNTs agglomeration. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of laminated plates.