• Carbon letters
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• 제14권4호
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• pp.210-217
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• 2013

The synthesis of carbon nanomaterials (CNMs) by a chemical vapor deposition method using three different plant oils as precursors is presented. Because there are four parameters involved in the synthesis of CNM (i.e., the precursor, reaction temperature of the furnace, catalysts, and the carrier gas), each having three variables, it was decided to use the Taguchi optimization method with the 'the larger the better' concept. The best parameter regarding the yield of carbon varied for each type of precursor oil. It was a temperature of $900^{\circ}C$ + Ni as a catalyst for neem oil; $700^{\circ}C$ + Co for karanja oil and $500^{\circ}C$ + Zn as a catalyst for castor oil. The morphology of the nanocarbon produced was also impacted by different parameters. Neem oil and castor oil produced carbon nanotube (CNT) at $900^{\circ}C$; at lower temperatures, sphere-like structures developed. In contrast, karanja oil produced CNTs at all the assessed temperatures. X-ray diffraction and Raman diffraction analyses confirmed that the nanocarbon (both carbon nano beads and CNTs) produced were graphitic in nature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.393-394
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• 2008

Carbon nanotubes are attractive nano-structured materials because of their remarkable electronic, physical, chemical properties. Due to these reasons, application researches of CNTs are actively processed on the display, the electronic element, the nano-diode fields and the semiconductor element. Today, The major issue of semiconductor technique are via and interconnects. CNTs are used to make via and interconnects because of high electric currents density and high heat transfer. Control of the orientation of grown CNTs is very important thing for making via and interconnects. Via are horizontal growth of CNTs and interconnects are vertical growth of CNTs. This research is based on the experiment using control of gas flow directions and DC bias. Scanning Electron Microscope (SEM) was used to check this experiment.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.15-18
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• 2004

Nondestructive damage sensing and mechanical properties for thermal treated carbon nanotube(CNT) and nanofiber(CNF)/epoxy composites were investigated using electro-micromechanical technique. Carbon black (CB) was used only for the comparison. Electro-micromechanical techniques were applied to obtain the fiber damage and stress transferring effect of carbon nanocomposites with their contents. Thermal treatment and temperature affected on apparent modulus and electrical properties on nanocomposites due to enhanced inherent properties of each CNMs. Coefficient of variation (COV) of volumetric electrical resistance can be used to obtain the dispersion degree indirectly for various CNMs. Dispersion and surface modification are very important parameters to obtain improved mechanical and electrical properties of CNMs for multifunctional applications. Further optimized functionalization and dispersion conditions will be investigated for the following work continuously.

• Composites Research
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• 제29권4호
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• pp.138-144
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• 2016

최근 유해한 전자파 문제에 대응하여 사용되는 전자파 차폐 물질에 대한 관심이 대두되고 있다. 우선, 전통적으로 사용되는 전도성이 높은 금속 기반 물질들이 있지만, 무겁고 부식성에 대한 한계가 있기에 이를 극복할 수 있는, 가볍고 기계적 강도가 우수하고, 부식에 대한 내구성이 있으며 전기 전도성이 높은 탄소계 물질들이 대두되었다. 탄소계 물질을 phase별로 나누어, 그래핀, CNT와 같은 1-phase 단일계 탄소계 물질부터 단일계 탄소물질에 금속이 추가되거나, 서로 다른 탄소계 물질이 혼합된 2-phase 탄소계 물질, 서로 다른 탄소계 물질에 기능성 금속이 추가된 3-phase 탄소계 물질순으로 각각의 특징을 소개하였다.

• 한국기계가공학회지
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• 제14권5호
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• pp.28-35
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• 2015

This paper introduces a resistance scanning-type flexible tactile sensor for intelligent robots and presents the output characteristics of the sensor via signal processing. The sensor was produced via the lamination method using multi-walled carbon nanotubes (a conductive material), an insulator, and Tango-plus (an elastic material). Analog and digital signal processing boards were produced to analyze the output signal of the sensor. The analog signal processing board was made up of an integrator and an amplifier for signal stability, and the digital signal processing board was made up of an IIR filter for noise removal. Finally, the sensor output for the contact force was confirmed through experiments.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.799-804
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• 2016

A miniature X-ray tube based on a carbon-nanotube electron emitter has been employed for the application to a dental radiography. The miniature X-ray tube has an outer diameter of 7 mm and a length of 47 mm. The miniature X-ray tube is operated in a negative high-voltage mode in which the X-ray target is electrically grounded. In addition, X-rays are generated only to the teeth directions using a collimator while X-rays generated to other directions are shielded. Hence, the X-ray tube can be safely inserted into a human mouth. Using the intra-oral X-ray tube, a dental radiography is demonstrated where the positions of an X-ray source and a sensor are reversed compared with a conventional dental radiography system. X-ray images of five neighboring teeth are obtained and, furthermore, both left and right molar images are achieved by a single X-ray shot of the miniature X-ray tube.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.297-298
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• 2005

We have fabricated twisted nematic (TN) liquid crystal cells doped by carbon nanotubes (CNTs) with different CNT wt. %. With a minute amount doping, multi-walled CNTs did not perturb the liquid crystal orientations at the off- and on-state. The hysteresis studies of voltage-dependent capacitance (V-C) under the influence of electric field generated by ac and dc voltage show that the residual do, which is tightly related to image sticking problem in liquid crystal displays, is greatly reduced due to ion trapping by CNTs. Also, the V-C hysteresis shows dependency of capacitance on concentration of multi-walled CNTs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1220-1221
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• 2008

Submicron-sized conical-type tungsten(W) field-emitters based on carbon nanotubes(CNTs) are fabricated with the configuration of CNTs/catalyst(Ni)/buffer(Al/Ni/TiN)/W-tip. This study focuses on elucidating how the Al/Ni/TiN stacked buffer layer affects the structural properties of CNTs and the electron-emission characteristics of CNT-emitters. Field-emission scanning electron microscopy(FESEM), high-resolution transmission electron microscopy(HRTEM), and x-ray photoelectron spectroscopy(XPS) are used to monitor the nanostructures, surface morphologies, chemical bonds of all the catalysts and CNTs grown. The crystalline structure of CNTs is also characterized by Raman spectroscopy. Furthermore, the measurement of field-emission characteristics for the field-emitters fabricated shows that the emitter using the Al/Ni/TiN stacked buffer reveals the excellent performances.

• Structural Engineering and Mechanics
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• 제64권3호
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• pp.381-390
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• 2017

Present paper deals with the large amplitude flexural vibration of carbon nanotube reinforced composite (CNTRC) plates. Distribution of CNTs as reinforcements may be uniform or functionally graded (FG). The equivalent material properties of the composite media are obtained according to a refined rule of mixtures which contains efficiency parameters. To account for the large deformations, von $K{\acute{a}}rm{\acute{a}}n$ type of geometrical nonlinearity is included into the formulation. The matrix representation of the governing equations is obtained according to the Ritz method where the basic shape functions are written in terms of the Chebyshev polynomials. Time dependency of the problem is eliminated by means of the Galerkin method and the resulting nonlinear eigenvalue problem is solved employing a direct displacement control approach. Results are obtained for completely clamped and completely simply supported plates. Results are first validated for the especial cases of FG-CNTRC and cross-ply laminated plates. Afterwards, parametric studies are given for FG-CNTRC plates with different boundary conditions. It is shown that, nonlinear frequencies are highly dependent to the volume fraction and dispersion profiles of CNTs. Furthermore, mode redistribution is observed in both simply supported and clamped FG-CNTRC plates.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.55.1-55.1
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• 2010

차세대 디스플레이용 전극 재료는 투명하면서도 낮은 저항값을 가져야 하는 투명 전극 재료로 금속, 금속산화물, 전도성 고분자, 탄소재료 등을 들 수 있다. 금속재료는 전도도는 우수하지만, 낮은 투과도로 투명전극 재료로 적절하지 않고, 대표적인 금속산화물 재료인 indium tin oxide (ITO)의 경우, 우수한 투과성과 낮은 면저항을 기반으로 차세대 디스플레이용 전극으로 현재 사용되고 있다. 하지만 ITO 박막은 휘거나 접을 때 기계적 안정성이 취약한 문제점을 나타내고 있다. 이러한 문제점을 극복하기 위해 전도성과 탄성계수가 높고, 저온에서 대면적 공정이 가능한 CNT을 투명 박막 전극 연구가 활발히 진행되고 있다. 하지만 투명전극 제조시, 탄소 나노튜브 간의 van der waals 인력에 의한 응집 현상으로 인한 분산의 불안정성과 분산제 사용으로 인하여 탄소 나노튜브 박막전극의 전기적, 광학적 특성이 저하를 야기한다. 이에 본 실험에서는 아크 방전 공정으로 합성한 SWCNT 분산액을 사용하여 spray coating 방법으로 glass 위에 박막을 형성하였다. SWCNT 투명 박막 전극 위에 DC sputtering을 이용하여 얇은Ni를 도포한 후, $450{\sim}500^{\circ}C$, ethylene gas 분위기의 thermal CVD방법으로 Carbon NanoFibers (CNFs)를 생성시킴과 동시에 분산제를 burning out하였다. CNF 성장 전후의 투명 박막의 전기적 특성은 four point probe를 이용하여 면저항과 UV-vis 장비를 이용하여 가시광선 영역에서의 광학적 투과도를 측정 비교하였다.