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671.
Kyung Min Byun Shuler M.L. Sung June Kim Soon Joon Yoon Donghyun Kim 《Lightwave Technology, Journal of》2008,26(11):1472-1478
A nanowire-mediated surface plasmon resonance (SPR) imaging is numerically investigated for enhanced sensitivity. The results calculated by rigorous coupled-wave analysis present that interplays between localized surface plasmons and surface plasmon polaritons contribute to sensitivity enhancement. Compared to conventional thin film-based SPR imaging measurement, an optimal nanowire structure can provide sensitivity enhancement by 3.44 times as well as highly linear detection property for quantification of surface reactions of interests. This paper demonstrates the potential and limitation for a highly sensitive, label-free, and real-time SPR imaging sensor based on periodic metallic nanowires. 相似文献
672.
Myung-Kwang Byun Daeyoung Park Byeong Gi Lee 《Communications, IEEE Transactions on》2008,56(12):2105-2115
In this paper, we analyze the performance of spacetime codes and propose a distance spectrum computation method in fast Rayleigh fading channels. We first derive a new FER upper bound using the union bound and the PEP upper bound in the fast fading environment. The derived FER upper bound is very accurate, requires only the distance spectrum of the spacetime code, and takes a closed-form expression. Then we propose a distance spectrum computation method of space-time codes in fast fading channels, which exploits the symmetric property of the error state diagram in space-time trellis coded MPSK modulation to reduce the computation complexity. Numerical results illustrate that the derived FER bound is tight enough to estimate the performance of space-time codes in fast fading channels with sufficient accuracy. 相似文献
673.
674.
J.L. Gräfe F.E. McNeill S.H. Byun D.R. Chettle M.D. Noseworthy 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(15):2451-2457
Gadolinium (Gd)-based contrast agents are a valuable diagnostic aid for magnetic resonance imaging (MRI). The amount of free Gd deposited in tissues following contrast enhanced MRI is of toxicological concern. The McMaster University in vivo prompt gamma neutron activation analysis facility has been adapted for the detection of Gd in the kidney, liver, and the leg muscle. A simple model of the HPGe detector used for detection of the prompt γ-rays following Gd neutron capture has been created using Monte Carlo simulation. A separate simulation describing the neutron collimation and shielding apparatus has been modified to determine the neutron capture rate in the Gd phantoms. The MCNP simulation results have been confirmed by experimental measurement. The deviations between MCNP and the experiment were between 1% and 18%, with an average deviation of 3.8 ± 6.7%. The validated MCNP model is to be used to improve the Gd in vivo measurement sensitivity by determining the best neutron moderator/reflector arrangement. 相似文献
675.
Highly ordered self-organized TiO2 nanotube arrays prepared by a multi-step anodic oxidation process
S. C. Han J. M. Doh J. K. Yoon G. H. Kim J. Y. Byun S. H. Han K. T. Hong S. I. Kwun 《Metals and Materials International》2009,15(3):493-499
Highly ordered TiO2 nanotube arrays were prepared using a self-templating multi-step anodic oxidation process in a fluoride-containing electrolyte.
The microstructures, chemical compositions, and phases of the self-organized TiO2 nanotube arrays were analyzed by FESEM, XPS, and XRD, respectively. Hexagonal packing density in TiO2 nanotube arrays significantly improved after the the multi-step anodic oxidation. The area densities of the hexagonal TiO2 nanotube arrays increased approximately 3 times from the first to second step in the anodic oxidation steps process (4.9
μm−2 to 16.4 μm−2), but there was no difference between the second and third step (16.4 μm−2 to 16.0 μm−2). The as-anodized TiO2 nanotube array had an amorphous structure and it transformed to an anatase phase during the annealing process at 450 °C for
1 h. The as-anodized TiO2 nanotube arrays adsorbed the fluoride, hydrocarbon groups (CH), hydroxyl groups (OH, C-OH), and carboxyl groups (O = C-OH)
on their surfaces. 相似文献
676.
Ji-Young Lee Gilsoo Han Yu-Chan Kim Ji-Young Byun Jae-il Jang Hyun-Kwang Seok Seok-Jo Yang 《Metals and Materials International》2009,15(6):955-961
The corrosion behavior of pure magnesium that has different content ratio of impurities (such as Fe/Mn ratio) in Hanks’ solution
was investigated in order to tailor the lifetime of biodegradable implant made of pure magnesium. Two distinct stages of corrosion
were observed: a slow corrosion rate stage and a subsequent fast corrosion rate stage. The first stage was characterized by
uniform corrosion that produced magnesium hydroxide and calcium phosphate film on a magnesium surface, resulting in a slow
corrosion rate. The second stage with an abrupt increase in the corrosion rate was induced by Fe precipitates and was stimulated
by an increase in the Fe/Mn ratio. This corrosion was developed to a preferred crystallographic pitting corrosion where the
pits propagated along the preferred crystallographic plane and several layers of Mg planes with narrow interplanar space remained
uncorroded. From this study, it is expected that the lifetime of the biodegradable implant made of pure Mg can be tailored
by controlling the amount and ratio of the impurities. 相似文献
677.
Current methods for monitoring chloride in steam condensate in thermal power plants cannot measure the recommended target level (2 ppb) or are too complex and maintenance intensive for smaller plants. We propose a new relatively low-cost, easy-to-use, low-maintenance method, in which chloride in steam condensate is separated and concentrated with reverse osmosis membranes and the chloride in the concentrate stream is measured using an ion-selective electrode. This concentration-and-measurement system was demonstrated to accurately and quickly detect changes in chloride levels in steam condensate at operationally relevant levels (2–10 ppb) and as low as 0.6 ppb. 相似文献
678.
A general optimization method for vapor-cooled current leads is presented with taking into account the effect of convection heat transfer and extended surfaces. This analytical work is considered as a unified design method, since one formulation calculates the minimum heat load and the corresponding optimal design condition for arbitrary heat transfer condition, spanning two limiting cases—the zero convection (or conduction-cooled leads) and the perfect heat transfer. It is clearly shown that the augmentation of the convective cooling can reduce the heat load to a certain extent, but the optimum lead parameter required to minimize the heat load for the finite heat transfer may not exist between the two limiting values. A new dimensionless parameter called the Ch number is introduced to conveniently incorporate the convection effect into the optimization. The present method is demonstrated for two specific lead designs that have been recently developed for 10 kA level of applications. 相似文献
679.
Wonoh Lee Moon-Kwang Um Joon-Hyung Byun Philippe Boisse Jian Cao 《International Journal of Material Forming》2010,3(2):1217-1227
Through the international corporative benchmark works, the material characterization of the woven fabric composites has been examined to better understand their mechanical properties and to provide the process design information for numerical analysis. As the second stage of the benchmark work, the double-dome geometry has been used to illustrate the effect of numerical schemes on the forming behaviors of the woven composites parts. To account for the change of fiber orientation under the large deformation, the non-orthogonal constitutive model was utilized and nonlinear friction behavior was incorporated in the simulation. The equivalent material properties based on the contact status were used for the thermo-stamping process. Furthermore, we incorporated a recently developed non-orthogonal model which captures the dependency of shear behavior of woven fabric composites on the tensions in yarns. Simulation results showed the effect of coupling on the predicted forming behavior for the double-dome parts. As numerical results, blank draw-in, punch force history and fiber orientation after forming have been compared based on various numerical models and methods. 相似文献
680.
Pitch estimation is important in various speech research areas, but when the speech is noisy, accurate pitch estimation with conventional pitch detectors is almost impossible. To solve this problem, we propose a new pitch detection algorithm for noisy speech using a noise whitening technique on the background noise and obtain successful results. 相似文献