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971.
Young-Gyu Kim Seok-Beom Cho Pil-Jong Kim Boo-Kil Kwon 《Journal of Mechanical Science and Technology》2006,20(3):329-334
This paper presents the evaluation of LPG (Liquefied petroleum gas) regulators for home use. For the evaluation, several properties
of the regulators were experimentally analyzed, such as the operation of safety device, the adjusting and lock-up pressure,
the adjusting spring and the diaphragm, with respect to the used time of the regulators. Experimental results showed that
the initial operation performances of regulators were degraded with increase of the service time and also showed that the
degradation of the performance and material property could become serious after about six-year-use of the regulators. 相似文献
972.
Cho K.J. Kim W.J. Stapleton S.P. Kim J.H. Lee B. Choi J.J. Kim J.Y. 《Electronics letters》2006,42(12):704-705
A 40 W gallium-nitride microwave Doherty power amplifier for WCDMA repeater applications is presented. The main amplifier and peaking amplifier are implemented using two 20 W PEP GaN HEMTs. Performance is evaluated for broadband gain, power efficiency and adjacent-channel-power-ratio (ACPR). Experimental results of the GaN Doherty amplifier yielded a power gain of over 11 dB from 1.8 to 2.5 GHz, 68% power added efficiency at 40 W peak power. Good linearity performance of -48 dBc ACPR is obtained at a peak-to-average ratio of 9.8 dB. 相似文献
973.
J. R. Cho K. W. Kim J. K. Lee T. H. Park W. Y. Lee 《International journal for numerical methods in engineering》2002,55(6):733-752
In this paper, we address analytical and numerical studies on the free vibration of fluid–structure interaction problems considering the fluid compressibility. According to the separation of variables together with the boundary condition enforcement, we first derive a compressible‐fluid velocity potential function. Next, we split the structure region into the wet and dry parts, for which we apply the Novozhilov thin shell theory. Combining two dynamic displacement fields, for two split structure parts, using the displacement compatibility conditions, we finally obtain a simultaneous equation system for computing natural frequencies and modes. According to the derived analytical formulae, we compute natural frequencies and modes, stress resultants, together with the comparison with the FEM analysis and the incompressible case. Numerical results show, compared to the incompressible case, that the compressible case produces lower natural frequencies and, furthermore, the relative difference is influenced by the slenderness of tanks and the relative liquid fill height. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
974.
975.
Chang Seo Park Byung Jin Cho 《Electron Device Letters, IEEE》2005,26(11):796-798
High work function (4.9 eV) on high-/spl kappa/ gate dielectric, which is suitable for bulk p-MOSFET, has been achieved using fully silicided (FUSI) Pt/sub x/Si gate without boron predoping of polysilicon. High concentration of Pt in FUSI Pt/sub x/Si using Ti capping layer on Pt in the FUSI process is a key to achieving high work function and reduced Fermi-level pinning on high-/spl kappa/ dielectric. By combining with substituted Al (SA) gate for nMOSFET, a wide range of work function difference (0.65 eV) between n and pMOSFETs is demonstrated, without any adverse effects of polysilicon predoping. 相似文献
976.
Faist J. Sirtori C. Capasso F. Sivco D.L. Baillargeon J.N. Hutchinson A.L. Cho A.Y. 《Photonics Technology Letters, IEEE》1998,10(8):1100-1102
High-temperature operation (T=320 K) of quantum cascade lasers has been extended to 11.5-μm wavelengths with high performances. Peak-pulsed optical power of 55 mW is obtained at 300 K with a high T 0=172 K, in good agreement with our theoretical model 相似文献
977.
978.
979.
S.H. Cho C.C. Lu M. Hovinen K. Nam V. Vusirikala J.H. Song F.G. Johnson D. Stone M. Dagenais 《Photonics Technology Letters, IEEE》1997,9(8):1081-1083
We have systematically studied the well number dependence of the linewidth enhancement factor in strained quantum-well (QW) lasers and have demonstrated experimentally that the linewidth enhancement factor can be reduced from /spl sim/9.4 to /spl sim/2.0 by increasing the number of compressively strained QW's from 2 to 8. This behavior is primarily due to an increase in the differential gain with the number of QW's. 相似文献
980.
Performance assessment through bootstrap 总被引:4,自引:0,他引:4
Cho K. Meer P. Cabrera J. 《IEEE transactions on pattern analysis and machine intelligence》1997,19(11):1185-1198
A new performance evaluation paradigm for computer vision systems is proposed. In real situation, the complexity of the input data and/or of the computational procedure can make traditional error propagation methods infeasible. The new approach exploits a resampling technique recently introduced in statistics, the bootstrap. Distributions for the output variables are obtained by perturbing the nuisance properties of the input, i.e., properties with no relevance for the output under ideal conditions. From these bootstrap distributions, the confidence in the adequacy of the assumptions embedded into the computational procedure for the given input is derived. As an example, the new paradigm is applied to the task of edge detection. The performance of several edge detection methods is compared both for synthetic data and real images. The confidence in the output can be used to obtain an edgemap independent of the gradient magnitude 相似文献