• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.181-181
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• 2010

Few-walled carbon nanotubes (FWNTs)-based field emitters with long term stability are fabricated by using a spray method. Tetraethylorthosilicate (TEOS) sol as a binder was mixed with dispersed solution of FWNTs to enhance the adhesion of FWNTs on the cathode substrate. Due to the strong intermolecular interaction of TEOS to the functional groups attached on CNTs and substrate, CNTs are tightly adhered to the cathode electrode when heat treatment is performed at $150^{\circ}C$ for 1 hour, resulting in a stable electron emission of CNT emitters for long time. Excellent field emission characteristics were exhibited, with a large field enhancement factor and low turn-on voltage, comparable to those of CNT emitters fabricated by a screen printing of CNT paste. Therefore, FWNTs / TEOS hybrid films could be utilized as an alternative for the efficient and reliable field emitters.

• Journal of Magnetics
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• 제17권1호
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• pp.9-12
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• 2012

Attempts to dope carbon nanotube (CNT) with impurities in order to control the electronic properties of the CNT is a natural course of action. Boron is known to improve both the structural and electronic properties. In this report, we study the field emission properties of Boron-doped double-walled CNT (DWCNT). Boron-doped DWCNT films were fabricated by catalytic decomposition of tetrahydrofuran and triisopropyl borate over a Fe-Mo/MgO catalyst at $900^{\circ}C$. We measured the field emission current by varying the doping amount of Boron from 0.8 to 1.8 wt%. As the amount of doped boron in the DWCNT increases, the turn-on-field of the DWCNT decreases drastically from 6 V/${\mu}m$ to 2 V/${\mu}m$. The current density of undoped CNT is 0.6 mA/$cm^2$ at 9 V, but a doped-DWCNT sample with 1.8 wt% achieved the same current density only at only 3.8 V. This shows that boron doped DWCNTs are potentially useful in low voltage operative field emitting device such as large area flat panel displays.

• Composites Research
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• 제26권3호
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• pp.147-154
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• 2013

탄소나노튜브(CNT)와 그래핀 같은 나노카본은 기계적 성질이 탁월하고 직경 대 길이의 비가 커서 고분자 복합재료의 강화재로 이상적인 것으로 생각된다. 그동안 나노탄소의 특성을 복합재료에 그대로 전환시키기 위한 많은 연구들이 있었지만 여전히 해결되지 않은 많은 문제, 예를 들면 효율적인 공정의 개발 등이 숙제로 남아있다. 이 총설에서는 CNT와 그래핀을 이용하는 나노탄소 고분자 복합재료 분야에서 이룬 그 간의 발전을 살펴보았으며, 여러 가지 나노탄소 고분자 복합재료에서 기계적인 강화가 어느 정도 이루어지는지 비교, 분석하고 향후 연구개발 방향을 전망하였다.

• 한국염색가공학회지
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• 제32권1호
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• pp.65-71
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• 2020

Electrical energy is used for heating and cooling because electric cars do not have engines and cooling water. The downside is that when the heating and cooling system is applied to electric vehicles, about 40 percent of the energy is spent on heating and cooling, which is less efficient in winter. This has increased demand for electric vehicle battery efficiency. In this study, the condensation and dispersion of carbon nanotubes were controlled, and carbon fibers and composite slurry were manufactured without binders to manufacture paper. Manufactured by content showed the highest heat generation characteristic at 143℃ with a carbon fiber content ratio of 20wt% and confirmed that the heat temperature rises with increasing pressure. The plane heaters made through this study can be applied to a variety of products other than electric vehicles because they can be simplified by process and high temperature.

• Carbon letters
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• 제25권
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• pp.14-24
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• 2018

Electrochemical properties and performance of composites performed by incorporating metal oxide or metal hydroxide on carbon materials based on graphene and carbon nanotube (CNT) were analyzed. From the surface analysis by field emission scanning electron microscopy and field emission transmission electron microscopy, it was confirmed that graphene, CNT and metal materials are well dispersed in the ternary composites. In addition, structural and elemental analyses of the composite were conducted. The electrochemical characteristics of the ternary composites were analyzed by cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy in 6 M KOH, or $1M\;Na_2SO_4$ electrolyte solution. The highest specific capacitance was $1622F\;g^{-1}$ obtained for NiCo-containing graphene with NiCo ratio of 2 to 1 (GNiCo 2:1) and the GNS/single-walled carbon $nanotubes/Ni(OH)_2$ (20 wt%) composite had the maximum specific capacitance of $1149F\;g^{-1}$. The specific capacitance and rate-capability of the $CNT/MnO_2/reduced$ graphene oxide (RGO) composites were improved as compared to the $MnO_2/RGO$ composites without CNTs. The $MnO_2/RGO$ composite containing 20 wt% CNT with reference to RGO exhibited the best specific capacitance of $208.9F\;g^{-1}$ at a current density of $0.5A\;g^{-1}$ and 77.2% capacitance retention at a current density of $10A\;g^{-1}$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.297.2-297.2
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• 2016

Photoacoustic generation of ultrasound is an effective approach for development of high-frequency and high-amplitude ultrasound transmitters. This requires an efficient energy converter from optical input to acoustic output. For such photoacoustic conversion, various light-absorbing materials have been used such as metallic coating, dye-doped polymer composite, and nanostructure composite. These transmitters absorb laser pulses with 5-10 ns widths for generation of tens-of-MHz frequency ultrasound. The short optical pulse leads to rapid heating of the irradiated region and therefore fast thermal expansion before significant heat diffusion occurs to the surrounding. In this purpose, nanocomposite thin films containing gold nanoparticles, carbon nanotubes (CNTs), or carbon nanofibers have been recently proposed for high optical absorption, efficient thermoacosutic transfer, and mechanical robustness. These properties are necessary to produce a high-amplitude ultrasonic output under a low-energy optical input. Here, we investigate carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite transmitters and their nanostructure-originated characteristics enabling extraordinary energy conversion. We explain a thermoelastic energy conversion mechanism within the nanocomposite and examine nanostructures by using a scanning electron microscopy. Then, we measure laser-induced damage threshold of the transmitters against pulsed laser ablation. Particularly, laser-induced damage threshold has been largely overlooked so far in the development of photoacoustic transmitters. Higher damage threshold means that transmitters can withstand optical irradiation with higher laser energy and produce higher pressure output proportional to such optical input. We discuss an optimal design of CNT-PDMS composite transmitter for high-amplitude pressure generation (e.g. focused ultrasound transmitter) useful for therapeutic applications. It is fabricated using a focal structure (spherically concave substrate) that is coated with a CNT-PDMS composite layer. We also introduce some application examples of the high-amplitude focused transmitter based on the CNT-PDMS composite film.

• 센서학회지
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• 제30권4호
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• pp.255-260
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• 2021

We studied electrochemical sensors using printed carbon nanotube (CNT) film on a polyethylene terephthalate (PET) substrate. Multiwalled CNT films were printed on a PET substrate to study its feasibility as hazardous and noxious substances (HNS) detection sensor. The printed CNT film (PCF) with a 50 ㎛ thickness exhibited a specific resistance of 230 ohm. To determine the optimum sensor structure, a resistance-type PCF sensor (R-type PCF sensor) and a conductive-type PCF sensor (C-type PCF sensor) were fabricated and compared using diluted NH₃ droplets with various concentrations. The response magnitude, response time, sensitivity, linearity, and limit of detection (LOD) were compared, and it was concluded that the C-type PCF sensor exhibited superior performance. By applying a C-Type PCF sensor, we confirmed the detection performance of 12 types of floating HNS and the response of the sensor with selectivity according to the degree of polarity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.156-157
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• 2006

To improve mean-life and reliability of power cable in this study, we have investigated chemical properties showing by changing the content of Carbon nanotube(CNT) that is semiconductive additives for underground power transmission. Specimens were made of sheet form with the three of existing resins and the five of specimens for measurement. Chemical properties of specimens was measured by FT-ATR (Fourier Transform Attenuated Total Reflectance). The condition of specimens was a solid sheet. We could observe functional group (C=O, carbonyl group) of specimens through FT-ATR. From these experimental result, the concentration of functional group (C=O) was high according to increasing the content of Carbon nanotube. We could know CNT/EEA was excellent more than other specimens from above experimental results.

• 한국재료학회지
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• 제17권3호
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• pp.173-178
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• 2007

Carbon nanotube cathodes(CNT cathodes) with a trench structure similar to gated structure of triode-type cathode were fabricated by a screen printing method using multi-walled carbon nanotubes. The effects of surface treatments on CNT cathodes were investigated for high efficiency field emission displays(FEDs). A liquid method easily removed the organic residue and protruded the CNTs. Field emission properties were measured by using a diode-type mode. The liquid method produced a turn-on field of $1.4V/{\mu}m$. The emission current density was measured about $3.1mA/cm^{2}$ at the electric field of $3V/{\mu}m$. The liquid method showed a high potential applicable to the surface treatment for triode-type FEDs.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2006년도 춘계학술발표논문집
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• pp.223-226
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• 2006

The micro-gas sensor based on carbon nanotubes (CNTs) was fabricated and its gas sensing characteristics on nitrogen dioxide ($NO_2$) have been investigated. The sensor consists of a heater, an insulating layer, a pair of contact electrodes, and CNT-sensing film on a micromachined diaphragm. The heater plays a role in the temperature change to modify sensor operation. Gas sensor responses of CNT-film to $NO_2$ at room temperature are reported. The sensor exhibits a reversible response with a time constant of a few minutes at thermal treatment temperature of $130^{\circ}C$.