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排序方式: 共有2183条查询结果,搜索用时 312 毫秒
181.
Donglei Wei Yanlin Huang Jin Soo Kim Liang Shi Hyo Jin Seo 《Journal of Electronic Materials》2010,39(4):441-446
Well-crystallized Ca9ZnLi(PO4)7 ceramics were prepared by reactive pressureless sintering at atmospheric pressure. The single-phase Ca9ZnLi(PO4)7 ceramics were confirmed by x-ray diffraction (XRD). The dielectric and electrical properties were investigated over a wide
frequency range (1 Hz to 1 MHz) by complex impedance spectroscopy at different temperatures between 25°C and 600°C. A dielectric
anomaly was observed at 440°C, which might be related to the phase transition. The impedance Cole–Cole plot was used to analyze
the results of complex impedance measurements, revealing that the electrical properties depend strongly on frequency and temperature.
Two relaxation dispersions of the electrical parameters were found and analyzed in terms of bulk and grain-boundary ionic
transfer processes. The slope of the alternating-current (AC) conductivity over a wide range of temperatures provides activation
energies from 0.48 eV to 1.69 eV. These results suggest that the conduction process is of the mixed type. 相似文献
182.
A High-Order Immersed Boundary Method for Acoustic Wave Scattering and Low-Mach Number Flow-Induced Sound in Complex Geometries 总被引:1,自引:0,他引:1
A new sharp-interface immersed boundary method based approach for the computation of low-Mach number flow-induced sound around complex geometries is described. The underlying approach is based on a hydrodynamic/acoustic splitting technique where the incompressible flow is first computed using a second-order accurate immersed boundary solver. This is followed by the computation of sound using the linearized perturbed compressible equations (LPCE). The primary contribution of the current work is the development of a versatile, high-order accurate immersed boundary method for solving the LPCE in complex domains. This new method applies the boundary condition on the immersed boundary to a high-order by combining the ghost-cell approach with a weighted least-squares error method based on a high-order approximating polynomial. The method is validated for canonical acoustic wave scattering and flow-induced noise problems. Applications of this technique to relatively complex cases of practical interest are also presented. 相似文献
183.
Wook Jae Yoo Kyoung Won Jang Jeong Ki Seo Ji Yeon Heo Jin Soo Moon Jae Hoon Jun Jang-Yeon Park Bongsoo Lee 《Optical Review》2011,18(1):132-138
In this study, two types of nasal-cavity-attached fiber-optic respiration sensors have been fabricated for noninvasive respiratory
monitoring. One is a silver halide optical-fiber-based respiration sensor that can measure the variations of infrared radiation
generated by the respiratory airflow from a nasal cavity. The other is a thermochromic-pigment-based fiber-optic respiration
sensor that can measure the intensity of reflected light which changes owing to color variations of the temperature-sensing
film according to the temperature difference between inspiratory and expiratory air. We have demonstrated the similarities
of the respiratory signals using the fiber-optic respiration sensors and the temperature transducer of the BIOPAC? system.
In addition, we verified that respiratory signals without the deterioration of the MR image can be obtained using the fiber-optic
respiration sensors. It is anticipated that the proposed noninvasive fiberoptic respiration sensors will be highly effective
for respiratory monitoring of a patient during MRI procedures. 相似文献
184.
Jiyeon Lee Dahye Im Yajie Liu Jing Fang Xibao Tian Minsu Kim Prof. Wen-Bin Zhang Prof. Jongcheol Seo 《Angewandte Chemie (International ed. in English)》2023,62(51):e202314980
A technique combining ion mobility spectrometry-mass spectrometry (IMS-MS) and supercharging electrospray ionization (ESI) has been demonstrated to differentiate protein chemical topology effectively. Incorporating as many charges as possible into proteins via supercharging ESI allows the protein chains to be largely unfolded and stretched, revealing their hidden chemical topology. Different chemical topologies result in differing geometrical sizes of the unfolded proteins due to constraints in torsional rotations in cyclic domains. By introducing new topological indices, such as the chain-length-normalized collision cross-section (CCS) and the maximum charge state (zM) in the extensively unfolded state, we were able to successfully differentiate various protein chemical topologies, including linear chains, ring-containing topologies (lasso, tadpole, multicyclics, etc.), and mechanically interlocked rings, like catenanes. 相似文献
185.
Il-Suk Kang Young-Su Kim Hyun-Sang Seo Chi Won Ahn Jun-Mo Yang Wook-Jung Hwang 《Current Applied Physics》2011,11(6):1319-1321
The effect of two-step hydrogenation, consisting of plasma hydrogenation and annealing in hydrogen, on the hysteresis phenomenon of metal-induced unilaterally crystallized silicon thin-film transistors (MIUC-Si TFTs) was investigated. The large hysteresis level of the conventional MIUC-Si TFTs caused a wide variation of the drain current with the previous gate voltage. As the plasma exposure time increased, the plasma hydrogenation commonly used for stability in poly-Si TFTs was found to increase the hysteresis level of MIUC-Si TFTs after a minimum point. This is because plasma-induced damages correlated with unique defects of MIUC-Si such as metal-related weak bonds, are accompanied by passivation. The following annealing repaired the damages. Consequently the hysteresis level was lower, which resulted in a narrower variation of the drain current. 相似文献
186.
Yong-Hee Park Jungwon Kim Hyoungjoon Kim Ilsoo Kim Ki-Young Lee Dongjea Seo Heon-Jin Choi Woochul Kim 《Applied Physics A: Materials Science & Processing》2011,104(1):7-14
In this paper, we synthesize VLS-grown rough Si nanowires using Mn as a catalyst with various surface roughnesses and diameters
and measured their thermal conductivities. We grew the nanowires by a combination vapor-liquid-solid and vapor-solid mechanism
for longitudinal and radial growth, respectively. The surface roughness was controlled from smooth up to about 37 nm by the
radial growth. Our measurements showed that the thermal conductivity of rough surface Si nanowires is significantly lower
than that of smooth surface nanowires and decreased with increasing surface roughness even though the diameter of the smooth
nanowire was lower than that of the rough nanowires. Considering both nanowires were grown via the same growth mechanism,
these outcomes clearly demonstrate that the rough surface induces phonon scattering and reduces thermal conductivity with
this nanoscale-hole-free nanowires. Control of roughness induced phonon scattering in Si nanowires holds promise for novel
thermoelectric devices with high figures of merit. 相似文献
187.
Kitajima K Yoshikawa T Seo Y Ohno Y Yano Y Miki A Kanda T Kanata N Azuma T Sugimura K 《Magnetic resonance imaging》2011,29(4):579-583
Budd-Chiari syndrome (BCS) is a rare disorder caused by the obstruction of hepatic venous outflow, leading to sinusoidal congestion, ischemic injury to liver cells and portal hypertension. Long-term survival largely depends on whether hepatocellular carcinoma occurs. A recently available liver-specific contrast medium, gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA), reportedly has high diagnostic capability for detection of malignant liver tumors. However, there has been no report of the sue of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) for BCS. We present a case of chronic BCS who underwent both gadopentetate dimeglumine (Gd-DTPA) and Gd-EOB-DTPA-enhanced MRI. Hepatic congestion and edema were seen as slightly hypointense areas on Gd-EOB-DTPA-enhanced hepatobiliary-phase images, although these areas were observed as slightly hyperintense on previously obtained Gd-DTPA-enhanced delayed-phase image. Reduced uptake of Gd-EOB-DTPA by hepatocytes in the region of congestion or edema may account for this difference, which should be recognized in image interpretations. 相似文献
188.
Ihyeok Seo 《Mathematische Nachrichten》2014,287(5-6):699-703
In this note we study the property of unique continuation for solutions of , where V is in a function class of potentials including for . In particular, when , our result gives a unique continuation theorem for the fractional Schrödinger operator in the full range of α values. 相似文献
189.
We obtain a global unique continuation result for the differential inequality |(i∂t+Δ)u|?|V(x)u| in Rn+1. This is the first result on global unique continuation for the Schrödinger equation with time-independent potentials V(x) in Rn. Our method is based on a new type of Carleman estimates for the operator i∂t+Δ on Rn+1. As a corollary of the result, we also obtain a new unique continuation result for some parabolic equations. 相似文献
190.
Yongsok Seo 《ournal of non Newtonian Fluid Mechanics》2011,166(3-4):241-243
A new scaling function capable of modeling the yield stress behavior of electrorheological (ER) fluids through the full range of electric fields is proposed. In spite of its simple form, a comparison of the model predictions with experimental data for both ac and dc fields and the polarization model shows that the proposed model correctly predicts the yield stress behavior both quantitatively as well as qualitatively. 相似文献