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991.
Seo-Yeong Yeo Tae-Hyeong Kwon Chang-Sun Park Chang-Il Kim Ji-Sun Yun Young-Hun Jeong Youn-Woo Hong Jeong-Ho Cho Jong-Hoo Paik 《Journal of Electroceramics》2018,41(1-4):1-8
The main objective of our work is to increase transmittance in the mid infrared region by removing impurities through the pre-heating treatment of zinc sulfide (ZnS) produced by hydrothermal synthesis. The pre-heating treatment proceeded at 450 to 600 °C for 2 h under vacuum atmosphere (10?2 Torr). It was confirmed that the particle size increased as the pre-heating temperature increased. Additionally, all ZnS nano powders had a sphalerite (cubic) structure unaffected by pre-heating treatment. The ZnS nano powders were sintered by hot-press sintering method. As the pre-heating temperature increased, transmittance was improved due to the decreasing of porosity, increase of particle size, and the removal of impurities (carbon and sulfate). However, when the pre-heating treatment temperature was 600 °C, the transmittance slightly decreased due to the formation of a hexagonal phase. The ZnS ceramic with pre-heating treatment at 550 °C showed the highest transmittance (71.6%) and density (99.9%). 相似文献
992.
993.
For the purpose of balancing charge carriers’ transport, we designed and synthesized two new compounds that are composed of both electron- and hole-transporting structural moieties: electron-transporting moieties are diaryl-1,3,4-oxadizole (Oxa) groups and hole transport moieties carbazole (Cz), or triphenylamine (TPA) moieties. The compounds formed amorphous glassy films when vacuum deposited and their glass transition temperature (Tg) was close to or higher than 150 °C. Their electronic structures (the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and Eg values) and hole and electron mobilities in the compounds were studied. A couple of compounds bearing oxadiazole moieties revealed the electron mobility greater than 1.0 × 10−4 cm2/(V s) at the electric field of 7.5 × 105 V/cm. The single layer light-emitting electroluminescence (EL) devices show that the external quantum efficiencies of the devices fabricated with those compounds having balanced carrier mobilities are much higher than those of the compounds composed of predominantly hole- or electron-transporting moieties. 相似文献
994.
Do -Hun Chin Moon-Chul Yoon Seung -Kil Son Hyun -Deog Cho 《Journal of Mechanical Science and Technology》2007,21(10):1637-1643
For the investigation of the chatter modes, the power spectrum of the parametric time series model was adopted and analyzed
at several mixed conditions of different revolution. This paper describes a methodology for an application of several time
series such asAR (forward-backward, burg, least square, Yule Walker, geometric lattice, instrumental variable),ARX (least square, instrumental variable),ARMAX, ARMA, Box Jenkins, Output Error. To estimate the chatter mode using their spectral analysis their results were compared with one another. As a result, it
was proven that several time series methods can be used for chatter mode estimation. Among them, theARX, ARMAX and instrumental variable methods (iv4) are more desirable and reliable than the other algorithm for the exact calculation
of the chatter mode in endmilling. Among three cutting forces, the z direction cutting force,Fz, has more powerful characteristics of chatter occurring than the cutting forces,Fx andFy, in the sense that weak mode is calculated exactly and there is no shifted or pseudo mode in the estimated power spectra
of endmilling forces. 相似文献
995.
Sun Hyok Chang Seung Kwan Kim Moo-Jung Chu Jong-Hyun Lee 《Electronics letters》2002,38(16):865-867
A simple method of Rayleigh scattering noise calculation in fibre Raman amplifiers is proposed. Using the method, it is disclosed that the optimal Raman pump power is lower when the Rayleigh scattering of both signal and amplified spontaneous emission (ASE) are considered than when the Rayleigh scattering of ASE only is considered 相似文献
996.
Design and fabrication of a significantly shortened multimode interference coupler for polarization splitter application 总被引:4,自引:0,他引:4
Jung Moo Hong Hyun Ho Ryu Soon Ryong Park Jae Wan Jeong Seung Gol Lee El-Hang Lee Se-Geun Park Deokha Woo Sunho Kim Beom-Hoan O 《Photonics Technology Letters, IEEE》2003,15(1):72-74
We report that we have successfully designed and fabricated a significantly shortened multimode interference coupler for application in polarization splitter, using a phenomenon that we termed "quasi-state" (QS) imaging effect. First, we identified and analyzed the QS imaging effect, and, based on the QS analysis, designed and fabricated a novel multimode interference (MMI) device with its split length shortened to 1/5 of a normally designed MMI split length. The fabrication is simple and cost effective and the fabricated device shows outstanding characteristics in extinction ratio, signal homogeneity, excess loss, and tolerance in the length of the splitter. 相似文献
997.
The functional roles subserved by G(alpha)z, a G protein alpha subunit found predominantly in neuronal tissues, have remained largely undefined. Here, we report that G(alpha)z coupled neurotransmitter receptors to N-type Ca2+ channels when transiently overexpressed in rat sympathetic neurons. The G(alpha)z-mediated inhibition was voltage dependent and PTX insensitive. Recovery from G(alpha)z-mediated inhibition was extremely slow but accelerated by coexpression with RGS proteins. G(alpha)z selectively interacted with a subset of receptors that ordinarily couple to N-type Ca2+ channels via PTX-sensitive Go/i proteins. In addition, G(alpha)z rescued the activation of heterologously expressed GIRK channels in PTX-treated neurons. These results suggest that G(alpha)z is capable of coupling receptors to ion channels and might underlie PTX-insensitive ion channel modulation observed in neurons under physiological and pathological conditions. 相似文献
998.
Mycobacterium szulgai is a rare cause of human infections, and when present it is mostly known to cause lung infection. We report the first case of isolated Mycobacterium szulgai osteomyelitis in a 68-year-old woman on chronic immunosuppressive therapy. Review of the literature revealed a total of three other cases of M. szulgai osteomyelitis. In all these cases there was evidence of hematogenous or contiguous spread, including one with extensive dissemination. Pulmonary M. szulgai infections tend to occur in patients with chronic lung disease and/or concomitant lung infections, whereas osteomyelitis tends to occur in patients who have severe immunosuppression secondary to disease or drugs. 相似文献
999.
Jeong D.G. Gibson J.D. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1993,39(3):786-804
Lattice vector quantizer design procedures for nonuniform sources are presented. The procedures yield lattice vector quantizers with excellent performance and retaining the structure required for fast quantization. Analytical methods for truncating and scaling lattices to be used in vector quantizations are given, and their utility is demonstrated for independent and identically distributed (i.i.d.) Gaussian and Laplacian sources. An analytical technique for piecewise linear multidimensional compandor designs is evaluated for i.i.d. Gaussian and Laplacian sources by comparing its performance to that of the other vector quantizers 相似文献
1000.
Joseph I. Goldstein Seung K. Choi Frans J. J. Van Loo Guillaume F. Bastin Rudi Metselaar 《Journal of the American Ceramic Society》1995,78(2):313-322
Reactions between Ti and SiO2 were studied at 1373 K (1100°C) under vacuum conditions using planar diffusion couples. A method to correct for the presence of surface oxide was developed which led to improved oxygen measurements with the electron probe microanalyzer. An isothermal section through the Ti-Si-O phase diagram at 1373 K was determined using measured diffusion paths and phase compositions in equilibrated alloys. The experimentally determined isothermal section was compared to isothermal sections calculated using thermodynamic data. In addition the sequence of reaction layers formed in the diffusion couples is discussed in terms of thermodynamic activity diagrams. 相似文献