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排序方式: 共有148条查询结果,搜索用时 31 毫秒
1.
Ho Nam Kwon Man Geun Kim Il-Han Hwang Young Kab Yun Seon-Ju Kim Jong-Hyun Lee 《Photonics Technology Letters, IEEE》2005,17(4):774-776
We developed a micromachined X-type 2/spl times/4 optical add-drop module (OADM) featuring no difference in propagation length. Four pairs of lensed fibers are aligned in "X" position, and four micromirrors are located between the pairs of optical fibers. The OADM was fabricated utilizing a silicon-on-insulator process. Electrostatic comb actuators can be driven up to 90 /spl mu/m to change the light path within 1 ms. The insertion loss and the on-off ratio were less than 3 and 70 dB, respectively. The loss uniformity in every channel was 1.5 dB. 相似文献
2.
Analysis and characterization of traveling-wave electrode in electroabsorption modulator for radio-on-fiber application 总被引:1,自引:0,他引:1
Jiyoun Lim Young-Shik Kang Kwang-Seong Choi Jong-Hyun Lee Sung-Bock Kim Jeha Kim 《Lightwave Technology, Journal of》2003,21(12):3004-3010
Comparing with a lumped electroabsorption modulator (EAM), we show the merits of a long EAM with traveling-wave electrode with high radio-frequency (RF) gain that could be used in high-frequency analog application. By terminating the RF output port with the characteristic impedance of 30 /spl Omega/, the device exhibited a large enhancement of 6 dB above 10 GHz in the electrical-to-optical response and a wide fractional bandwidth as estimated from simulation. In addition, an input impedance matching circuit of stub embedded on the device chip was found to be very effective for improving RF characteristics in the narrow band of frequency. 相似文献
3.
Jong-Hyun Hwang Myoung-Seoup Han Dae-Young Kim Joong-Geun Youn 《Journal of Materials Engineering and Performance》2006,15(3):328-335
High-temperature wear characteristics between plasma spray coated piston rings and cylinder liners were investigated to find
the optimum combination of coating materials using the disc-on-plate reciprocating wear test in dry conditions. The disc and
plate represented the piston ring and the cylinder liner, respectively. Coating materials studied were Cr2O3-NiCr, Cr2O3-NiCr-Mo, and Cr3C2-NiCr-Mo. Plasma spray conditions for the coating materials were established adjusting stand-off distance to obtain a coating
with a porosity content of ∼5%. It was found that a dissimilar coating combination of Cr2O3-NiCr-Mo and Cr3C2-NiCr-Mo provided the best antiwear performance. The addition of molybdenum was found to be beneficial to improve the wear
resistance of the coating. Hardness differences between mating surfaces were also important factors in determining the wear
characteristics, so that it should be controlled below 300 in Vickers hardness under dry conditions. Adhesive wear accompanying
with metal transfer was a dominant wear mechanism for dry conditions. 相似文献
4.
A torsional micromechanical scanner was fabricated using photosensitive polymer (SU-8). The proposed polymer-based optical
microscanner with reduced torsional stiffness offers a new approach to increase scanning angles. The scanner consists of two
parts; the top layer (micro mirror and electrodes) and the bottom layer (anchors and electrodes). The SU-8 scanner is actuated
by electrostatic force generated by gap-closing electrodes. For the fabricated optical scanner with the mirror size of 3 × 3 mm2, the experimentally obtained scanning angles were 0.43° for 60 Hz (non-resonant) and 1.54° for 1.13 kHz (resonant) at the input voltage of 160 V. This paper also proposes a simple and new fabrication method, which
can effectively control the stiffness of the torsional springs by molding SU-8 photoresist through V-groove on the silicon
substrate, thereby increasing the scanning angles. 相似文献
5.
Enterococcus spp. from powdered infant formula and follow-on formulas were identified and characterized for antibiotic susceptibility to confirm the enterococcal safety. Seventy-three Enterococcus from 96 powdered infant formulas and 26 strains from 33 follow-on formulas were isolated. More than 90% of Enterococcus in the foods were E. faecium. E. casseliflavus, and E. faecalis were also isolated. All Enterococcus were sensitive to ampicillin, penicillin, tetracycline, and vancomycin. However, 2 E. casseliflavus showed low resistance to vacomycin by minimum inhibitory concentration 4.0 μg/mL. Multiplex PCR indicated no existence of highly hazardous vancomycinresistant vanA and vanB genes. The isolates also showed the broad susceptibilities to erythromycin, ripampin, and streptomycin. Major strains of about 60% were intermediately and highly resistant to erythromycin and streptomycin, respectively. However, Enterococcus resistances to those antibiotics were not high and similar to those of Enterococcus from the other evaluated foods. Therefore, it appeared that powdered infant formula and follow-on formula might be safe to Enterococcus with regard to vancomycin and the antibiotics. 相似文献
6.
Sang-Ik Han Jong-Hyun Chae Kristin Bilyeu J. Grover Shannon Jeong-Dong Lee 《Journal of the American Oil Chemists' Society》2014,91(2):229-234
Soybean [Glycine max (L.) Merr] with increased oleic acid is desirable to improve oxidative stability and functionality of soybean seed oil. Recently, soybean genotypes with high oleic acid (≥70 %) were developed by breeding programs. Efficient and effective identification of high oleic acid soybean genotypes using non-destructive near infrared reflectance (NIR) on whole seeds would greatly enhance progress in breeding programs. The objective of this study was to develop a calibration equation for NIR determination of high oleic acid from single soybean seeds. A total of 600 intact, single F2 seeds were scanned by NIR. Spectral data were collected between 400 and 2,500 nm at 2 nm intervals. The relationship between NIR spectral patterns of each soybean seed and its oleic acid content was examined. The best predicted equations for oleic acid were selected on the basis of minimizing the standard error of cross-validation and increasing the coefficient of determination. Validation demonstrated that the equations for determining total oleic acid and over 50 % oleic acid content had high predictive ability (r 2 = 0.91 and r 2 = 0.99, respectively). To validate the newly developed equation, F2 seeds from a different genetic background were tested. Again, high oleic acid from single soybean seeds was accurately predicted from various genetic backgrounds. Therefore, applying the calibration equations to NIR will be useful to rapidly and efficiently select high oleic acid soybean genotypes in breeding programs. 相似文献
7.
8.
Chang-Kyun Oh Yun-Jae Kim Jong-Hyun Baek Woo-sik Kim 《International Journal of Fracture》2007,143(2):119-133
The present paper proposes ductile failure criteria in terms of true fracture strain (the equivalent strain to fracture) as
a function of the stress triaxiality (defined by the ratio of the hydrostatic stress to the equivalent stress) for the API
X65 steel. To determine the stress-modified fracture strain, smooth and notched tensile bars with four different notch radii
are tested, from which true fracture strains are determined as a function of the notch radius. Then detailed elastic–plastic,
large strain finite element analyses are performed to estimate variations of stress triaxiality in the tensile bars, which
leads to true fracture strains as a function of the stress triaxiality, by combining them with experimental results. Two different
failure criteria are proposed, one based on local stress and strain information at the site where failure initiation is likely
to take place, and the other based on averaged stress and strain information over the ligament where ductile fracture is expected.
As a case study, ligament failures of API X65 pipes with a gouge are predicted and compared with experimental data. 相似文献
9.
Reaction properties and interfacial intermetallics for Sn−xAg−0.5Cu solders as a function of Ag content 总被引:1,自引:0,他引:1
Jong-Hyun Lee A-Mi Yu Jeong-Han Kim Mok-Soon Kim Namhyun Kang 《Metals and Materials International》2008,14(5):649-654
Wetting and interfacial reactions were investigated for Sn−xAg−0.5Cu alloys, in which the Ag content had a variation from
x=1.0 to x=4.0. Differential scanning calorimetry (DSC) was used to investigate the range of the melting temperature and the
solidification temperature by measuring the endothermic and the exothermic heat flow, respectively. Low Ag contents increased
the melting temperature ranges and deteriorated the wetting properties such as zero cross time and wetting force measured
at two seconds. The extent of undercooling increased and the thickness of intermetallic compounds (IMC) decreased as the Ag
content decreased. As the Ag content decreased, the initial IMC thickness decreased due to the large undercooling and, during
the solid aging at 170°C, the IMC growth slightly decelerated because of the small diffusion coefficient. For the application
of good drop shock reliability, Sn−Ag−Cu solder of low Ag content should be beneficial due to the restraint of the IMC growth
(Cu6Sn5 and Cu3Sn) and of the coarse plate-like IMC (Ag3Sn). 相似文献
10.
Jongdeog Kim Byung Seok Choi Hogyeong Yun Su Hwan Oh Jong-Hyun Lee Hyunsung Ko Kwang-Seong Choi Sahnggi Park Jong Tae Moon Moon-Ho Park 《Photonics Technology Letters, IEEE》2004,16(11):2430-2432
A sampled-grating distributed Bragg reflector laser module having an integrated multiwavelength locker has been developed and evaluated. The uniquely designed wavelength locker made of thermally controlled etalon has provided uniform wavelength monitoring and very stable wavelength locking in the 188-ITU grid channels (37 nm) with 25-GHz spacing. Over the case temperature from -5/spl deg/C to 65/spl deg/C, the laser wavelength was locked within /spl plusmn/0.5 GHz, and the total power consumption of the module was less than 4 W. 相似文献