• Journal of Sensor Science and Technology
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• v.31 no.4
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• pp.214-217
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• 2022

The effect of inductively coupled plasma (ICP) treatment with O₂ gas on the surface properties of poly(ether sulfone) (PES) was investigated. X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical characteristics of the O₂ plasma-treated PES films. The surface roughness of the pristine and O₂ plasma-treated PES films for different RF powers of the ICP was determined using an atomic force microscope (AFM). The contact angles of the PES films were also measured, using which the surface free energies were calculated. The O1s XPS spectra of the PES films revealed that the number of polar functional groups increased following the O₂ plasma treatment. The AFM analysis showed the average surface roughness increased from 1.01 to 4.48 nm as the RF power of the ICP was increased. The contact angle measurements revealed that the PES films became more hydrophilic as the RF power of the ICP was increased. The total surface energy increased with the RF power of the ICP, resulting from the increased polar energy component.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.3
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• pp.86-91
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• 2020

An important factor of rough road modeling is analyzing the shear behavior properties of the rough road. These properties influence the drawbar pull of the tool when interacting with the soil used in agriculture. Furthermore, shear behavior properties are important because sinkage and shear stress are generated when wheels drive on rough roads. In this study, we performed a direct shear test to investigate the shear behavior properties of soils and compare with the direct shear simulation; shear force derived by the coupled analysis of discrete element method; and multi-body dynamics. Soil contact parameters were measured in a wheel and soil contact simulation followed by comparison of the simulated and experimentally measured shear force.

• Macromolecular Research
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• v.17 no.1
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• pp.8-13
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• 2009

Natural fiber-filled polymer composites have attracted great interest due to increasing environmental concerns and their low costs. In this study, the properties of rice husk flour-filled polypropylene (PP) were analysed in view of the large quantities of this agricultural product available as residue in Brazil. The rice husk flour (RHF) was characterized by SEM and particle size distribution. The properties of the composites were studied by MFI, DMA, DSC and TGA analyses. A commercial PP modified with maleic anhydride (MAPP) was used as coupling agent. It was verified that RHF decreased the MFI of the composites and that the coupling agent decreased it even more. The efficiency of MAPP was confirmed by the high storage modulus and high loss factor of the coupled composites.

• Coupled systems mechanics
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• v.6 no.1
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• pp.1-15
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• 2017

Despite the exceptional mechanical properties of individual carbon nanotubes (CNTs), the effective properties of CNT-reinforced composites remain below expectations. The composite's microstructure has been identified as a key factor in explaining this discrepancy. In this contribution, a method for generating representative volume elements of aligned CNT sheets is presented. The model captures material characteristics such as random waviness and entanglement of individual nanotubes. Thus it allows studying microstructural effects on the composite's effective properties. Simulations investigating the strengthening effect of the application of a pre-stretch on the CNTs are carried out and found to be in very good agreement with experimental values. They highlight the importance of the nanotube's waviness and entanglement for the mechanical behavior of the composite. The presented representative volume elements are the first to accurately capture the waviness and entanglement of CNT sheets for realistically high volume fractions.

• Coupled systems mechanics
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• v.6 no.1
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• pp.75-96
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• 2017

As electron donor/acceptor materials for organic photovoltaic cells, small-molecules donors/acceptor are attracting more and more attention. In this work, we investigated the electronic structures, electrochemical properties, and charge carrier transport properties of four recently-synthesized small-molecule donors/acceptor, namely, DPDCPB (A), DPDCTB (B), DTDCPB (A1), and DTDCTB (B1), by a series of ab initio calculations. The calculations look into the electronic structure of singly oxidized and reduced molecules, the first anodic and cathodic potentials, and the electrochemical gaps. Results of our calculations were in accord with those from experiments. Using Marcus theory, we also computed the reorganization energies of hole/electron hoppings, as well as hole/electron transfer integrals of multiple possible molecular dimer configurations. Our calculations indicated that the electron/hole transport properties are very sensitive to the relative separations/orientations between neighboring molecules. Due to high reorganization energies for electron hopping, the hole mobilities in the molecular crystals are at least an order of magnitude higher than the electron mobilities.

• Coupled systems mechanics
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• v.7 no.6
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• pp.691-705
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• 2018

In this paper, nonlinear displacements of laminated composite beams are investigated under non-uniform temperature rising with temperature dependent physical properties. Total Lagrangian approach is used in conjunction with the Timoshenko beam theory for nonlinear kinematic model. Material properties of the laminated composite beam are temperature dependent. In the solution of the nonlinear problem, incremental displacement-based finite element method is used with Newton-Raphson iteration method. The distinctive feature of this study is nonlinear thermal analysis of Timoshenko Laminated beams full geometric non-linearity and by using finite element method. In this study, the differences between temperature dependent and independent physical properties are investigated for laminated composite beams for nonlinear case. Effects of fiber orientation angles, the stacking sequence of laminates and temperature on the nonlinear displacements are examined and discussed in detail.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.1
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• pp.25-40
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• 2004

The supersonic shock wave generated by fully coupled explosion will change into subsonic shock wave, plastic wave, and elastic wave consecutively as the wave propagates through rock mass. While the estimation of the blast-induced peak pressure was the main aim of the companion paper, this paper will concentrate on the estimation of the rise time of blast-induced pressure. The rise time can be expressed as a function of explosive density, isentropic exponent, detonation velocity, exponential coefficient of the peak pressure attenuation, dynamic yield stress, plastic wave velocity, elastic wave velocity, rock density, Hugoniot parameters, etc. Parametric analysis was performed to pinpoint the most influential parameter that affects the rise time and it was found that rock properties are more sensitive than explosive properties. The probabilistic distribution of the rise time is evaluated by the Rosenblueth'S point estimate method from the probabilistic distributions of explosive properties and rock properties. Numerical analysis was performed to figure out the effect of rock properties and explosive properties on the uncertainty of blast-induced vibration. Uncertainty analysis showed that uncertainty of rock properties constitutes the main portion of blast-induced vibration uncertainty rather than that of explosive properties. Numerical analysis also showed that the loading rate, which is the ratio of the peak blasting pressure to the rise time, is the main influential factor on blast-induced vibration. The loading rate is again more influenced by rock properties than by explosive properties.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1915-1917
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• 2004

Inductively coupled plasma is commonly used for electrodeless lamp due to its ease of plasma generation. Optical characteristics significantly depend on the RF power and gas pressure of the plasma. This paper describes the measurement of luminance as a function of RF power and gas pressure with a goal of finding optimal operating conditions of the electrodeless lamp. The gas pressure was varied from 10 [mTorr] to 500 [mTorr] and the RF power was varied from 10 [W] to 200 [W]. It was found that the luminance tends to be decreased when argon pressure is increased, and the luminance is increased as RF power is increased. It was also found that the luminance per unit RF power is high when the argon pressure is low and when the RF power is in the range of 30 [W]${\sim}$40 [W].

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1541-1544
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• 2002

The concentration of B in steels is important due to its influence on mechanical properties of steel such as hardenability, hot workability, and creep resistance. An analytical method has been developed to determine B in steel samples by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). National Institute of Standard and Technology Standard Reference Material (NIST SRM) 348a was analyzed to validate the analytical method. The steel sample was digested in a centrifuge bottle with addition of aqua regia and $^{10}B$ spike isotope. Sample pH was then adjusted to higher than 10 to precipitate most matrix elements such as Fe, Cr, and Ni. After centrifugation, the supernatant solution was passed through a cation exchange column to enhance the matrix separation efficiency. B recovery efficiency was about 37%, while matrix removal efficiency was higher than 99.9% for major matrix elements. The isotope dilution method was used for quantification and the determined B concentration was in good agreement with the certified value.

• Journal of the Speleological Society of Korea
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• no.82
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• pp.1-4
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• 2007

In this paper, the etching of Au films using photoresist masks on Si substrates was investigated using a capacitively coupled plasma etch reactor. The advantages of plasma etch techniques over current methods for Au metalization include the ability to simplify the metalization process flow with respect to resist lift-off schemes, and the ability to cleanly remove etched material without sidewall redeposition, as is seen in ion milling. The etch properties were measured for different gas mixing ratios of CF4/Ar, and chamber pressures while the other conditions were fixed. According to statistical design of experiment (DOE), etching process of Au films was characterized and also 20 samples were fabricated followed by measuring etch rate, selectivity and etch profile. There is a chemical reaction between CF4 and Au. Au- F is hard to remove from the surface because of its high melting point. The etching products can be sputtered by Ar ion bombardment.