• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.218-219
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• 2007

This paper researched permittivity of carbon nanotube reinforced semiconductive shield materials for power cable in accordance with carbon nanotube content. Permittivity measured 1[Hz], 1[kHz], 1[Mhz] in frequency range, and range of temperature measured to 100$[^{\circ}C]$ from -50$[^{\circ}C]$. It is stable to 100$[^{\circ}C]$ from -50$[^{\circ}C]$ without different gap. But, in case of CNT:CB=100:0, permittivity decreased by temperature increment. Also, in case of CNT:CB=100:0, it shows highest permittivity. Permittivity of change have little no the power of influence by frequency, but in case of 1[Mhz], CNT:CB=100:0 of specimen decreased more than other frequency. This influence thinks phenomenon of induced electricity dispersion.

• Advances in aircraft and spacecraft science
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• v.6 no.3
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• pp.207-223
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• 2019

Current investigation deals with the thermal stability characteristics of carbon nanotube reinforced composite beams (CNTRC) on elastic foundation and subjected to external uniform temperature rise loading. The single-walled carbon nanotubes (SWCNTs) are supposed to have a distribution as being uniform or functionally graded form. The material properties of the matrix as well as reinforcements are presumed to be temperature dependent and evaluated through the extended rule of mixture which incorporates efficiency parameters to capture the size dependency of the nanocomposite properties. The governing differential equations are achieved based on the minimum total potential energy principle and Euler-Bernoulli beam model. The obtained results are checked with the available data in the literature. Numerical results are supplied to examine the effects of numerous parameters including length to thickness ratio, elastic foundations, temperature change, and nanotube volume fraction on the thermal stability behaviors of FG-CNT beams.

• Journal of Powder Materials
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• v.23 no.3
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• pp.213-220
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• 2016

In this study, bulk nickel-carbon nanotube (CNT) nanocomposites are synthesized by a novel method which includes a combination of ultrasonication, electrical explosion of wire in liquid and spark plasma sintering. The mechanical characteristics of the bulk Ni-CNT composites synthesized with CNT contents of 0.7, 1, 3 and 5 wt.% are investigated. X-ray diffraction, optical microscopy and field emission scanning electron microscopy techniques are used to observe the different phases, morphologies and structures of the composite powders as well as the sintered samples. The obtained results reveal that the as-synthesized composite exhibits substantial enhancement in the microhardness and values more than 140 HV are observed. However an empirical reinforcement limit of 3 wt.% is determined for the CNT content, beyond which, there is no significant improvement in the mechanical properties.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.2
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• pp.151-161
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• 2019

In this study, to evaluate the High Altitude Electromagnetic Pulse(HEMP) protection performance of UHPC/CNT composites by the content of Carbon nanotubes(CNTs), Electromagnetic Shielding Effectiveness(SE) test was performed based on MIL-STD-188-125-1. And the results were verified by applying the Antenna theory. In the case of UHPC with a thickness of 200 mm mixed with 1 % CNT of cement weight, the SE was 28.98 dB at 10 kHz and 45.94 dB at 1 GHz. Then the Scabbing limit thickness for bullet proof was computed based on the result of compressive strength test which was 170 MPa, and it was examined whether it satisfied the HEMP protection criteria. As a result, the required HEMP shielding criteria were satisfied in all frequency ranges as well as the scabbing limit thickness was reduced by up to 43 % compared with that of ordinary concrete.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1150-1153
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• 2008

The coupled oscillation of multi-walled carbon-nanotube (MWCNT) oscillators consisting of (5n, 5n) CNTs was investigated by molecular dynamics simulations. The results show that the inter-wall coupling leads to frequency splits. And there are consistently three primary frequency peaks for the quadric-walled, penta-walled and hexa-walled CNT oscillators. It is independent of the wall parameters, suggesting applications as triple-frequency generators. Furthermore, at least one of the primary frequencies of a MWCNT oscillator is lower than that of its double-walled counterpart.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.49-50
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• 2000

5.2" microtip field emission displays (FEDs) with high voltage applications are fabricated. Nano-structural analysis on microtips is performed for the reliable operation of FEDs. Chemical compositions on the apex of microtips are fully analyzed. A charging mechanism on spacers is simulated and experimentally confirmed with micro-images. A gas-aging mechanism is also studied with integration step of FEDs. The brightness of more than 300 $cd/m^2$ is achieved. In addition, as a new concept, 9" color carbon nanotube FEDs (CNT-FEDs) are introduced using well-aligned carbon nanotubes on glass substrates by paste squeeze and surface treatment techniques. A number of carbon nanotubes, $5-10/{\mu}m2$, are uniformly distributed over a large area. The turn-on fields of 1 $V/{\mu}m$ and field emission currents of 1.5 mA at 3 $V/{\mu}m$ are acquired. Different mechanisms between microtip FEDs and CNT-FEDs are discussed.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.169-172
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• 2001

We have investigated the mechanical deformation of carbon nanotube using TBMD(tight-binding molecular dynamics) simulation. We have studied four carbon nanotubes, armchair (6, 6), (7, 7), (8, 8), and (9, 9) carbon nanotubes whose length were same. As a result of study, we have known that the nanotube's yield force increases with incresing their diameter. It is similar between (6, 6) and (8, 8) CNT's force-strain curves. Also force-strain curve between (7,7) and (9, 9) CNTs are nearly same.

• Advances in nano research
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• v.6 no.1
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• pp.57-80
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• 2018

In this study, the thermal loading effect on free vibration characteristics of carbon nanotubes (CNTs) with multiple cracks is studied. Various boundary conditions for nanotube are taken in to account. In order to take the small scale effect, the nonlocal elasticity of Eringen is employed in the framework of Euler-Bernoulli beam theory. This theory states that the stress at a reference point is a function of strains at all points in the continuum. A cracked nanotube is assumed to be consisted of two segments that are connected by a rotational spring which is located in the position of the cracked section. Hamilton's principle is used to achieve the governing equations. Influences of the nonlocal parameter, crack severity, temperature change and the number of cracks on the system frequencies are investigated. Also, it is found that at room or lower temperature the natural frequency for CNT decreases as the value of temperature change increases, while at temperature higher than room temperature the natural frequency of CNT increases as the value of temperature change increases. Various boundary conditions have been applied to the nanotube.

• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.105-110
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• 2019

Effect of height on the size and shape of carbon nanotube (CNT) aggregates in the freeboard region of a bubbling fluidized bed ($0.15m\;i.d.{\times}2.6m\;high$) has been determined. Feret diameter and Heywood diameter of the CNT aggregates in the freeboard region of fluidized bed increased with increasing gas velocity. The average aggregate diameters and CNT particle number in the aggregates decreased with increasing of height in the freeboard. Aspect ratio increased as the location was closer to the surface of the dense phase, but decreased at the highest location. Solidity did not show any significant changes with height. The results showed the aggregates formation process is affected by the height in the freeboard. A correlation was proposed to predict the Heywood diameter of the CNT aggregates.

• Korean Journal of Applied Biomechanics
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• v.22 no.4
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• pp.429-435
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• 2012

The purpose of this study was to determine the biomechanical effect of wearing carbon nanotube-based insole on cushioning and muscle tuning during drop landing. Twenty male university students(age: $21.2{\pm}1.5yrs$, height: $175.4{\pm}4.7cm$, weight: $70.2{\pm}5.8kg$) who have no musculoskeletal disorder were recruited as the subjects. Average axial strain, average shear strain, inversion angle, linear velocity, angular velocity, vertical GRF and loading rate were determined for each trial. For each dependent variable, a one-way analysis of variance(ANOVA) with repeated measures was performed to test if significant difference existed among different three conditions(p<.05). The results showed that Average axial strain of line 4 was significantly less in CNT compared with EVA and PU during IP phase. The average shear strain was less in CNT compared with EVA and PU during other phases. The inversion angle was increased in CNT compared with EVA and PU during all phase. In linear velocity, angular velocity, vertical GRF and loading rate, there were no significant difference between the three groups. This result seems that fine particle of carbon nanotube couldn't make geometric form which can absolve impact force by increasing density through eliminating voids of forms. Thus, searching for methods that keep voids of forms may play a pivotal role in developing of insole. This has led to suggestions of the need for further biomechanical analysis to these factors.