• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.93-98
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• 2010

In this work, the electrochemical properties of surface treated multi-walled carbon nanotubes (MWNTs) were studied. Nitrogen and oxygen functional groups of the MWNTs were introduced by urea and acidic treatment, respectively. The surface functional groups of the MWNTs were confirmed by X-ray photoelectron spectroscopy (XPS) measurements and zeta-potential method. The characteristics of $N_2$ adsorption isotherm at 77 K, specific surface area, and total pore volumes were investigated by BET eqaution, BJH method and t-plot method. Electrochemical properties of the functionalized MWNTs were accumulated by cyclic voltammetry at the scan rates of 50 $mVs^{-1}$ and 100 $mVs^{-1}$ in 1M $H_2SO_4$ as electrolytes. As a result, the functionalized MWNTs led to an increase of capacitance as compared with pristine MWNTs. It was found that the increase of capacitance for urea treated MWNTs was attributed to the increase in density of surface functional groups, resulting in improving the wettability between electrode materials and charge species.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.177-182
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• 2003

The front-end side members of automobiles absorb most of the energy in a case of front-end collision. The front-end side members are required to have a high stiffness together with easiness to collapse sequentially to absorb more impact energy. The axial static collapse test (5mm/min) was conducted by using UTM for form different types of members which have different cross section shapes; single hat, single cap, double cap, and double hat. The single hat shaped section member has the typical standard section, which the double hat shape section has a symmetry in the center to have more stiffness. As a result of the test, the energy absorbing characteristic was analyzed for different section shapes. It turned out that the change of section shape influence the absorbing energy, the mean collapse load and the maximum collapse load, and the relation between the change of section shape and the collapse mode.

• Current Optics and Photonics
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• v.5 no.2
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• pp.180-185
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• 2021

A femtosecond-laser inscribed Yb:YAG surface channel waveguide (WG) laser with single-walled carbon nanotubes deposited on the top surface of the WG was passively Q-switched by evanescent field interaction. Q-switched operation of the 14-mm-long compact Yb:YAG WG laser was achieved near 1031 nm with two different pumping schemes (single- and double-pass pumping) with an output coupling transmission of 91%. The Q-switched pulse characteristics depending on the absorbed pump power were investigated for both pumping geometries and analyzed in detail based on theoretical modeling. The best performances (energy/pulse duration) for each configuration were 204.4 nJ/75 ns at a repetition rate of 1.87 MHz, and 201.1 nJ/81 ns at 1.75 MHz for single- and double-pass pumping, respectively.

• Advances in Energy Research
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• v.5 no.3
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• pp.219-226
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• 2017

Electrochemical double layer capacitors (EDLCs) have received a tremendous interest due to their suitability for diverse applications. They have been fabricated using different carbon based electrodes including activated carbons, single walled/multi walled carbon nano tubes. But, graphite which is one of the natural resources in Sri Lanka has not been given a considerable attention towards using for EDLCs though it is a famous carbon material. On the other hand, EDLCs are well reported with various liquid electrolytes which are associated with numerous drawbacks. Gel polymer electrolytes (GPE) are well known alternative for liquid electrolytes. In this paper, it is reported about an EDLC fabricated with a nano composite polyethylene oxide based GPE and two Sri Lankan graphite based electrodes. The composition of the GPE was [{(10PEO: $NaClO_4$) molar ratio}: 75wt.% PC] : 5 wt.% $TiO_2$. GPE was prepared using the solvent casting method. Two graphite electrodes were prepared by mixing 85% graphite and 15% polyvinylidenefluoride (PVdF) in acetone and casting n fluorine doped tin oxide glass plates. GPE film was sandwiched in between the two graphite electrodes. A non faradaic charge discharge mechanism was observed from the Cyclic Voltammetry study. GPE was stable in the potential windows from (-0.8 V-0.8 V) to (-1.5 V-1.5 V). By increasing the width of the potential window, single electrode specific capacity increased. Impedance plots confirmed the capacitive behavior at low frequency region. Galvanostatic charge discharge test yielded an average discharge capacity of $0.60Fg^{-1}$.

• 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.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.2
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• pp.194-201
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• 2005

For engineers in the industry, this study considers a reliable and practical finite element modeling technique to estimate the behavior of closed thin-walled members with spot weldings. Dynamic and static experiments confirm that the technique - modeling the spot weldings with solid elements which have the adjusted rotational freedoms and fill the welding space - Yields satisfactory results. Numerical studies on the double hat-shaped members. adopting this modeling technique. show the effect of the spot welding Pitch and the spot welding location in the flange on the stiffness of the members Using the principal stiffness and newly proposed GSPI(global stiffness performance index), we also carefully examine how the spot welding curvature, and sectional shape, etc.. synthetically influence the stiffness of a real excavator pillar in the field.

• Steel and Composite Structures
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• v.43 no.6
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• pp.797-808
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• 2022

This paper presents an investigation on the free vibration characteristics of functionally graded nanocomposite double-beams reinforced by single-walled carbon nanotubes (SWCNTs). The double-beams coupled by an interlayer spring, resting on the elastic foundation with a linear layer and shear layer, and is simply supported in thermal environments. The SWCNTs gradient distributed in the thickness direction of the beam forms different reinforcement patterns. The materials properties of the functionally graded carbon nanotube-reinforced composites (FG-CNTRC) are estimated by rule of mixture. The first order shear deformation theory and Euler-Lagrange variational principle are employed to derive the motion equations incorporating the thermal effects. The vibration characteristics under several patterns of reinforcement are presented and discussed. We conducted a series of studies aimed at revealing the effects of the spring stiffness, environment temperature, thickness ratios and carbon nanotube volume fraction on the nature frequency.

• Proceedings of the Korean Vacuum Society Conference
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• 2005.02a
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• pp.129-129
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• 2005

• Proceedings of the Korean Vacuum Society Conference
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• 2003.08a
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• pp.155-155
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• 2003

• Journal of the Semiconductor & Display Technology
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• v.6 no.1 s.18
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• pp.27-30
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• 2007

The gigahertz oscillator behavior of double-walled boron-nitride nanotube (BNNT) was investigated by using classical molecular dynamics simulations. The BNNT oscillator characteristics were compared to carbon-nanotube (CNT) and hybrid-C@BNNT oscillators. The results show that the BNNT oscillators are higher than the van der Waals force of the CNT oscillator. Since the frictional effects of BNNT oscillators are higher than that of a CNT oscillator, the damping factors of BNNT and hybrid oscillators are higher than that of a CNT oscillator.