• 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.

• Korean Journal of Materials Research
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• v.15 no.11
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• pp.711-716
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• 2005

The effects of change in the component of bonding materials in carbon nanotube cathode (CNT-cathode) on field enhancement and field emission characteristics were investigated. The field enhancement factor$\beta$ was dependent on the electrical conductivity of the bonding materials. The use of frit glass as a bonding material showed a higher field enhancement factor and better field emission characteristics than an Ag paste. The reason for why the frit glass showed better field emission characteristics can be summarized as follows. First, a frit glass improves the real aspect ratio of CNTs compared to an Ag paste. Second, the number of CNTs in CNT-cathodes is considerably reduced because the CNTs were extensively oxidized during $390^{\circ}C$ heat treatment in air atmosphere in the case of Ag paste.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.50-53
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• 2009

Multi-walled carbon nanotubes (MWNTs) were synthesized on different substrates (bare Si and $SiO_2$/Si substrate) to investigate dye-sensitized solar cell (DSSC) applications as counter electrode materials. The synthesis of MWNTs samples used identical conditions of a Fe catalyst created by thermal chemical vapor deposition at $900^{\circ}C$. It was found that the diameter of the MWNTs on the Si substrate sample is approximately $5{\sim}10nm$ larger than that of a $SiO_2$/Si substrate sample. Moreover, MWNTs on a Si substrate sample were well-crystallized in terms of their Raman spectrum. In addition, the MWNTs on Si substrate sample show an enhanced redox reaction, as observed through a smaller interface resistance and faster reaction rates in the EIS spectrum. The results show that DSSCs with a MWNT counter electrode on a bare Si substrate sample demonstrate energy conversion efficiency in excess of 1.4 %.

• Journal of IKEEE
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• v.25 no.3
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• pp.473-478
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• 2021

Although CNTFETs have attracted great attention due to their ability to increase semiconductor device performance by about 13 times, the commercialization of CNTFETs has been challenging because of the immature deposition process of CNTs. To overcome these difficulties, circuit design method considering the known limitations of the CNTFET manufacturing process is receiving increasing attention. SRAM is a major element constituting microprocessor and is regularly and repeatedly positioned in the cache memory; so, it has the advantage that CNTs can be more easily and densely deposited in SRAM than other circuit blocks. In order to take these advantages, this paper presents a circuit design method for SRAM cells considering CNT density and then evaluates its performance improvement using HSPICE simulation. As a result of simulation, it is found that when CNTFET is applied to SRAM, the gate width can be reduced by about 1.7 times and the read speed also can be improved by about 2 times when the CNT density was increased in the same gate width.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.3
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• pp.220-226
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• 2019

Magnesium hydride has a high hydrogen storage capacity (7.6 wt.%), and is cheap and lightweight, thus advantageous as a hydrogen storage alloy. However, Mg-based hydrides undergo hydrogenation/dehydrogenation at high temperature and pressure due to their thermodynamic stability and high oxidation reactivity. MWCNTs exhibit prominent catalytic effect on the hydrogen storage properties of $MgH_2$, weakening the interaction between Mg and H atoms and reducing the activation energy for nucleation of the metal phase by co-milling Mg with carbon nanotubes. Therefore, it is suggested that combining transition metals with carbon nanotubes as mixed dopants has a significant catalytic effect on the hydrogen storage properties of $MgH_2$. In this study, Material life cycle evaluation was performed to analyze the environmental impact characteristics of Mg-CaO-10 wt.% MWCNTs composites manufacturing process. The software of material life cycle assessment (MLCA) was Gabi 6. Through this, environmental impact assessment was performed for each process.

• Journal of the Korean GEO-environmental Society
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• v.20 no.1
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• pp.51-56
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• 2019

This paper presents a method to deice concrete pavement with carbon nanotube(CNT) as an heating material so as to avoid the adverse effects of conventional deicing method such as salt on the structure, function and environment. To this end, laboratory tests integrated with numerical simulations were conducted. In the laboratory tests, the CNT was embedded inside the concrete slab and generated the heat up to the target temperature of $60^{\circ}C$ in the freezer at temperature of $-10^{\circ}C$. Then, the surface temperature was measured to investigate how far the heat transfers on the surface at temperature of above $0^{\circ}C$. Also, three different spacings of 15, 20 and 30cm between CNTs were conducted to determine the maximum allowable spacing of CNT. Along with these experimental tests, heat transferring analysis conducted to validate the test results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.2
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• pp.126-129
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• 2021

We fabricated plate typed shunt resistors composed of carbon nanotube (CNT) and metal alloy for measuring DC current. CNT plates were prepared from dispersed CNT/Urethane solution by squeezing method. Cu/Ni alloys were prepared from composition-designed alloy wires for adjusting the temperature coefficient of resistance (TCR) by pressing them. As well, we fabricated a hybrid resistor by squeezing the CNT/Urethane solution on the metal alloy plate directly. In order to confirm the composition ratio of the Cu/Ni alloy, we used an energy-dispersed X-ray spectroscopy (EDX). Cross-section and surface morphology were analyzed by using a scanning electron microscopy (SEM). Finally, we measured the initial resistance of 2.35 Ω at 25℃ for the CNT paper resistor, 7.56 mΩ for the alloy resistor, and 7.38 mΩ for the hybrid resistor. The TCR was also measured to be -778.72 ppm/℃ at the temperature range between 25℃ to 125℃ for the CNT paper resistor, 824.06 ppm/℃ for the alloy resistor, and 17.61 ppm/℃ for the hybrid resistor. Some of the hybrid resistors showed a near-zero TCR of 1.38, -2.77, 2.66, and 5.49 ppm/℃, which might be the world best-value ever reported. Consequently, we could expect an error-free measurement of the DC current using this resistor.

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.229-235
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• 2021

This study presents a simple approach for the assembly of a free-standing conductive electronic nanofilm of single-walled carbon nanotubes (SWNTs) suitable for enzymatic electrochemical biosensors. A large-scale SWNT electronic film was successfully produced by the dialysis of p-Terphenyl-4,4''-dithiol (TPDT)-treated SWNTs. Furthermore, Horseradish peroxidase (HRP) was immobilized on the TPDT-SWNT electronic film, and the enzymatic detection of hydrogen peroxide (H₂O₂) was demonstrated without mediators. The detection of H₂O₂ in the negative potential range (-0.4 V vs. Ag/AgCl) was achieved by direct electron transfer of heme-based enzymes that were immobilized on the TPDT-SWNT electronic film. The SWNT-based biosensor exhibited a wide detection range of H₂O₂ from 10 µM to 10 mM. The HRP-doped SWNT electronic film achieved a high sensitivity of 342 ㎛A/mM·cm² and excellent selectivity against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, and acetaminophen.

• Tribology and Lubricants
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• v.39 no.1
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• pp.8-12
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• 2023

This study presents a molecular simulation of adhesion control between carbon nanotube (CNT) and Ag thin film deposited on silicon substrate. Rough and flat Ag thin film models were prepared to investigate the effect of surface roughness on adhesion force. Heat treatment was applied to the models to modify the adhesion characteristics of the Ag/CNT interface based on thermal wetting. Simulation results showed that the heat treatment altered the Ag thin film morphology by thermal wetting, causing an increase in contact area of Ag/CNT interface and the adhesion force for both the flat and rough models changed. Despite the increase in contact area, the adhesion force of flat Ag/CNT interface decreased after the heat treatment because of plastic deformation of the Ag thin film. The result suggests that internal stress of the CNT induced by the substrate deformation contributes in reduction of adhesion. Contrarily, heat treatment to the rough model increases adhesion force because of the expanded contact area. The contact area is speculated to be more influential to the adhesion force rather than the internal stress of the CNT on the rough Ag thin film, because the CNT on the rough model contains internal stress regardless of the heat treatment. Therefore, as demonstrated by simulation results, the heat treatment can prevent delamination or wear of CNT coating on a rough metallic substrate by thermal wetting phenomena.

• Journal of IKEEE
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• v.26 no.1
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• pp.83-88
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• 2022

With high performance and wide application, a CNTFET has been attracting a lot of attention as a next-eneration semiconductor, but the manufacturing process of CNTFET has not been mature enough, which makes commercialization difficult. In order to overcome the imperfections of the CNTFET manufacturing process and to increase the possibility of commercialization, this paper analyzes the CNTFET SRAM performance variation according to the CNTFET partial density change based on the recently reported CNTFET manufacturing process. Through HSPICE circuit simulation analysis using the existing 32nm CNTFET HSPICE library file, transistors whose performance variation is less sensitive to partial CNT density are selected among the six transistors constituting the SRAM cell and acceptable CNT density range is proposed. As the result of analysis, it is found that when the CNT density of the two transistors connected to the bit line in SRAM cell changed from 6/32nm to 8/32nm, the deviation of SRAM performance is less than 9% and when the CNT density is less than 5/32nm, the SRAM delay is increased by more than 8 time.