• Transactions on Electrical and Electronic Materials
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• v.15 no.4
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• pp.193-197
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• 2014

Si-carbon composites as anode materials for lithium rechargeable batteries were prepared simply by mixing Si nanoparticles with carbon black and/or graphite through a solution process. Si nanoparticles were well dispersed and deposited on the surface of the carbon in a tetrahydrofuran solution. Si-carbon composites showed more than 700 mAh/g of initial capacity under less than 20% loading of Si nanoparticle in the composites. While the electrode with only Si nanoparticles showed fast capacity fading during continuous cycling, Si-carbon composite electrodes showed higher capacities. The cycle performances of Si nanoparticles in composites containing graphite were improved due to the role of the graphite as a matrix.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.69-69
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• 2010

Carbon nano tubes (CNTs) have been attractive candidates for fundamental research studies due to their outstanding physical and chemical properties. High thermal and chemical stability and large surface area make CNTs an ideal platform for many nano materials systems. Several applications such as Several applications were proposed for CNTs many of which are concerned with conductive or high strength composites make them excellent candidates for a variety of energy conversion and storage technologies.

• Composites Research
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• v.17 no.5
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• pp.68-77
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• 2004

The electromagnetic (EM) absorption or shielding characteristics of a material is an important issue not only for military purpose but also for commercial purposes such as radar, electric or telecommunication devices. In order to design the effective electromagnetic wave absorber, the electromagnetic characteristics of the constituents of the material should be available in target frequency band. Also, it must be possible to predict the electromagnetic properties of absorbers with respect to the content of lossy ingredients. In this study, the dielectric properties of unsaturated polyester resins containing nano-size conductive carbon black powder were measured with a free space method in the X-band frequency range and analyzed with respect to the content of carbon black. Finally, the method for estimating the dielectric properties of polymeric resin containing conductive carbon black with respect to the EM frequency was developed and verified.

• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.257-261
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• 2006

Nano-structured carbon nitride $(CN_x)$ films were prepared by reactive RF magnetron sputtering with a DC bias at various deposition conditions, and the physical and electrical properties were investigated. FTIR spectrum indicated an ${alpha}C_3N_4$ peak in the films. The carbon nitride film deposited on Si substrate had a nano-structured surface morphology. The grain size was about 20 nm and the deposition rate was $1.7{\mu}m/hr$. When the $N_2/Ar$ ratio was 3/7, the level of nitrogen incorporation was 34.3 at%. The film had a low dielectric constant. The metal-insulator-semiconductor (MIS) capacitors that the carbon nitride was deposited as insulators, exhibited a typical C-V characteristics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1534-1540
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• 2004

This study aims to obtain fundamental understandings involving the manufacturing processes of nano-composites with chemically surface-modified multi-walled carbon nanotubes(MWCNTs), and explore the role of functionalized MWCNTs in the epoxy/MWCNT composites. For this purpose, MWCNTs were purified by the thermo-chemical oxidation process, and incorporated into an epoxy matrix by in situ polymerization process, the surface of MWCNTs were functionalized with carboxyl functions which were demonstrated by an infrared spectroscopy. The mechanical properties of epoxy/MWCNT nano-composites were measured to investigate the role of a chemically functionalized carbon nanotubes. To improve the dispersion quality of MWCNTs in the epoxy matrix, methanol and acetone were exploited as dispersion media with sonification. The epoxy/MWCNT nano-composites with 1 or 2 wt.％ addition of functionalized carbon nanotubes show an improved tensile strength and wear resistance in comparison with pure epoxy, which shows the mechanical load transfer improves through chemical bonds between epoxy and functionalized MWCNTs. The tensile strength with 7 wt.％ functionalized MWCNTs increases by 28％ and the wear resistance is dramatically improved by 100 times.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.333-339
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• 2011

In this work, electrochemical characteristics and optical transmittance of carbon nanotubes (CNTs) counter electrodes which had different amount of CNTs in CNTs slurries were analyzed. Two-step heat treatment processes were applied to achieve well-fabricated CNTs electrode. Three sets of CNTs electrodes and dye-sensitized solar cells (DSSCs) with CNTs counter electrodes were prepared. As the amount of CNTs increased, sheet resistance of CNTs electrode decreased. CNTs electrode with low sheet resistance had low electrochemical impedance and fast redox reaction. On the other hand, in case of CNTs counter electrode with low density of CNTs, performance of the dye-sensitized solar cell was improved due to its high optical transmittance. We found that the transmittance of CNTs counter electrode influence the performance of dye-sensitized solar cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.164-169
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• 2023

Nano Pt particles were dispersed on carbon-based supports by a polyol process for a catalyst application in a polymer electrolyte fuel cell. We tried to optimize the effect of pH on the electrostatic forces between the support and the Pt colloids. We investigated the relationship among the surface charges on the carbon support, the solution pH, and the concentration of a glycolate, and the Pt particle size. The produced catalyst with nano Pt particles on the support was evaluated by the long-term cyclic voltammetry (CV) performance test and compared with the results from a commercial catalyst. Our experimental results reveal that the pH-control can modify the particle size distribution and the dispersion of the nano Pt particles. This resulted in a cost-effective method for the synthesis of highly Pt loaded Pt/C catalysts for fuel cells better than a commercial catalyst system.

• Steel and Composite Structures
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• v.33 no.5
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• pp.653-661
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• 2019

In this paper aeroelastic behavior of 3-phase nano-composite beam-plate with double delaminations is investigated. It is tried to study the effect of carbon nano-tubes (CNTs) on critical flutter pressure of reinforced damaged nano-composite structures. In this case, the CNTs are appending to the polymer matrix uniformly. The Eshelby-Mori-Tanaka model is used to obtain the effective material properties of 3-phase nano-composite beam-plate. To investigate the aeroelastic behavior of delaminated beam-plate subjected to supersonic flow, it is assumed that the damaged segments are forced to vibrate together. The boundary conditions and auxiliary conditions at edges of delaminated segments are used to predict critical flutter pressure. The influence of CNTs and different delamination parameters such as delamination length, axial position and its position through thickness are investigated on critical flutter pressure.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.49-55
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• 2020

In order to improve the electromagnetic shielding rate of Carbon Fiber (CF), it was produced using the nickel nano-powder impregnating method. Using two types of nickel powder having thicknesses of 50 ㎛ and 100 ㎛, and a thermoplastic elastomer resin, a compound containing 10-20% nickel content was mixed and then manufactured through an extruder. The CF coated with the compound was woven and manufactured using a 1-ply specimen. The final nickel content of the specimen was verified using TGA and the distribution of nickel powder on the CF surface was verified using SEM. The metal shows a high shielding rate in the low-frequency band, but the shielding rate decreases at higher-frequency bands. The CF improves at the higher frequency band, and metals reflect electromagnetic waves while carbon absorbs electromagnetic waves. The study of shielding materials, which are stronger and lighter than metal, by using CF lighter than metal and enabling the shielding rate from low-frequency band to high-frequency band, confirmed that the larger the area coated with nickel nano-powder, the better the electromagnetic shielding performance. In particular, CF coated with a thickness of 100 ㎛ has a shielding rate similar to that of copper and can also be used for EV/HEV automotive cables and other applications in the future.

• Carbon letters
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• v.15 no.4
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• pp.268-276
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• 2014

Recently, methods that usea carbon-based filler, a conductive nanomaterial, have been investigated to develop composite fillers containing dielectric materials. In this study, we added geometric changes to a carbon fiber, a typical carbon-based filler material, by differentiating the orientation angle and the number of plies of the fiber. We also studied the electrical and electromagnetic shield characteristics. Based on the orientation angle of $0^{\circ}$, the orientation angle of the carbon fiber was changed between 0, 15, 30, 45, and $90^{\circ}$, and 2, 4, and 6 plies were stacked for each orientation angle. The maximum effect was found when the orientation angle was $90^{\circ}$, which was perpendicular to the electromagnetic wave flow, as compared to $0^{\circ}$, in which case the electrical resistance was small. Therefore, it is verified that the orientation angle has more of an effect on the electromagnetic interference shield performance than the number of plies.