• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.65-66
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• 2006

Solubility of single wall carbon nanotubes (SWNTs) has been determined in various dispersing media by using the solvent parameters such as Kamlet-Taft parameter and 3-dimensional parameters. Nitric acid-treated SWNTs exhibit significantly improved solubility in hydrogen bondable solvents as well as in solvent mixtures. The forming bucky gel with ionic liquid allows for the new group of dissolving solvent. The dissolution behavior of SWNTs provides a route for SWNT dispersion/exfoliation in preparing electrically conductive films such as transparent electrode.

• 한국전기전자재료학회논문지
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• 제20권11호
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• pp.959-964
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• 2007

To investigate the influence of partial discharge(PD) distribution characteristics due to various defects on the power cable joints interface, we used the K-means clustering method. As the result of PD number(n) distribution analyzing on $\Phi-n$ graph, the phase angle($\Phi$) of cluster centroid shifted to $0^{\circ}\;and\;180^{\circ}$ increasing with applying voltage. It was confirmed that the PD quantify(q) and euclidean distance of centroid were increased with applying voltage from the centroid distribution analyzing of $\Phi-q$ plane. The dispersion degree was increased with calculated standard deviation of the $\Phi-q$ cluster centroid. The PD number and mean value on $\Phi-q$ graph were some different by electric field concentration with defect types.

• 한국전기전자재료학회논문지
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• 제23권1호
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• pp.70-75
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• 2010

We have designed the backward wave oscillator operating at 24 GHz. From the research which sees researches in the goal which will design and will produce K-band BWO where is a backward wave oscillator which departs from cycle prisoner 24 GHz until now is higher. To design Chrencov instibility and branch of family used a slow cyclotron instibility. Calculation used a dispersion relation and in order for as the box over-flow not to happen, a asymtotic expansion. Used a beam mode and a waveguide mode and axial symmetry and expense used in compliance with sattle point interpreted the relationship of axial symmetry.

• Steel and Composite Structures
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• 제31권6호
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• pp.641-653
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• 2019

In this paper, wave propagation is studied and analyzed in double-layered nanotubes systems via the nonlocal strain gradient theory. To the author's knowledge, the present paper is the first to investigate the wave propagation characteristics of double-layered porous nanotubes systems. It is generally considered that the material properties of nanotubes are related to the porosity and hygro-thermal effects. The governing equations of the double-layered nanotubes systems are derived by using the Hamilton principle. The dispersion relations and displacement fields of wave propagation in the double nanotubes systems which experience three different types of motion are obtained and discussed. The results show that the phase velocities of the double nanotubes systems depend on porosity, humidity change, temperature change, material composition, non-local parameter, strain gradient parameter, interlayer spring, and wave number.

• 한국건설순환자원학회논문집
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• 제7권2호
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• pp.174-186
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• 2019

This paper reviews the development condition of nanomaterials used in concrete over years. The definitions of nanomaterial, nanotechnology, and nano-concrete are reviewed. The impacts of nanomaterials on cementitious material in the point of advantages and disadvantages are analyzed. Moreover, this paper analyzes and classifies the nanomaterials into the extra quality enhancement and modification to plain cementitious composite. Indeed, the outstanding properties of the embedded nanomaterials can be introduced to concrete such as the mechanical improvement, pore structure refinement, hydrate acceleration, and smartness modifying of self-cleaning, and/or self-sensing. Before the full potential of nanotechnology can be realized in concrete applications, various techniques have to be solved including proper dispersion, compatibility of the nanomaterials in cement, processing, manufacturing, safety, handling issues, scale-up, cost, the impact on the environment and human health.

• Advances in concrete construction
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• 제15권2호
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• pp.75-84
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• 2023

Currently, polymer matrix nanocomposites (PMCs) are a prominent area of research due to their outstanding mechanical, thermal, and durability properties. The increase in recent studies justifies the possibility of using PMCs in structural retrofitting and reconstruction of damaged infrastructure and serving as new structural material. Using nanotechnology, nanocomposite panels in flooring combine concrete and steel, providing a very high level of performance. In sports flooring, high-performance concrete has become a challenge for reducing sports injuries and refinement in rehabilitation. As a composite material, this type of resistant concrete is one of the most durable and complex multi-phase materials. This article uses polyvinyl alcohol polymer (PVC) and multi-walled carbon nanotubes as concrete matrix fillers. Solution methods have been used for dispersing PVC and carbon nanotubes in concrete. The water-cement ratio, carbon nanotube weight ratio, and heat treatment parameters influenced the concrete nanocomposite's tensile and compressive strength. The dispersion of carbon nanotubes in cement paste and the observation of nano-microcracks in concrete was evaluated by scanning electron microscope (SEM).

• Coupled systems mechanics
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• 제12권4호
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• pp.337-364
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• 2023

The Rayleigh wave propagation is considered in the structure of the functionally graded piezoelectric material (FGPM) layer over the elastic substrate. The elastic substrate loosely bonds the layer through a corrugated interface, whereas its upper boundary is also corrugated but stress-free. Additionally, the solutions for the FGPM layer and substrate are derived using the fundamental variable separable approach to convert the partial differential equation to an ordinary differential equation. The results with boundary conditions lead to dispersion relations for the electrically open and electrically short cases in the determinant form. The outcomes have been numerically analyzed using a specific model. The findings were presented in the form of graphs, which were created using Mathematica 7. Graphs are plotted for variations in wavenumber and phase velocity. The outcomes may help measure interface defects and design Surface Acoustic Wave (SAW) devices.

• 한국인쇄학회지
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• 제30권1호
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• pp.35-45
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• 2012

Polyacrylate dispersion(emulsion) as adhesive material was superior in quality such as preservation characteristics and reversibility. The tapes for repairing archival documents manufactured with four different types of formulation resulted in pH 7~8.8, soluble solid 50~52%, and viscosity 1,300~2,500 cps. Sample 4 of those was most excellent. Probably, sample 4 included inorganic materials such as MgO, silica gel, and zeolite. For selecting carrier of tape, tracing papers, were applied for manufacturing tapes and tested for adhesive strength and peel strength. Adhesive strength of tracing papers, was 3.1~3.8(N/10mm), 2.2~2.8(N/10mm), and 1.7-2.3(N/10mm), respectively. Peel strength was similar in all samples. To determine characteristic of conservation to the selected carriers, stability of deterioration was examined at conditions of $105^{\circ}C$ and $80^{\circ}C$ 65% for 7 days.

• 대한기계학회논문집A
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• 제28권10호
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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.

• 반도체디스플레이기술학회지
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• 제6권4호
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• pp.59-63
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• 2007

The CNTs are the most extensively studied material which are characterized by the complete property of matter, structure, and the large thermal conductivity (thermal conductivity of CNTs ~>2000W/mK vs. thermal conductivity of Aluminum ~> 204W/mK). Thus, they are successfully applied to the various fields. However, due to the strong agglomeration caused by the van der waal's force, their applications are limited. In the present study, a new method for CNTs dispersion was developed by using the mechanical dispersion, acid treatment, and then Cu was coated. This process produces CNTs/Cu nanocomposite powders, whereby the CNTs are homogeneously located within the Cu powders. The electrical properties of the CNTs/Cu nanocomposite were investigated.