1,721,107 research outputs found
High-sensitivity mode-locked fiber laser gyroscope
No full textWe report significant performance improvement of a mode-locked fiber laser gyroscope. A Fabry-Perot cavity GaAlAs laser diode whose front facet was antireflection coated was used as a gain medium. The rms noise equivalent rotation rate measured with a time-interval counter was improved to 0.06 deg/root h. The long-term drift of the gyroscope signal was reduced to 100 deg/h after a polarizer was inserted into the laser cavity formed with a polarization-maintaining fiber. (C) 1997 Optical Society of AmericaThis research was supported by the Agency for
Defense Development, Korea
Adhesion-promoted copolymers based on norbornene derivatives and maleic anhydride for 193-nm photoresists
No full textA copolymer of t-butyl 5-norbornene-2-carboxylate, 2-(2-methoxyethoxy)ethyl 5-norbornene-2-carboxylate, norbornene, and maleic anhydride was synthesized as a matrix polymer for ArF excimer laser lithography. Hydrophilic 2-(2-methoxyethoxy)ethyl ester groups are introduced into side chains of the matrix polymer in order to improve adhesion to a silicon substrate without causing cross-linking during a lithographic process. The resist formulated with the polymer shows better adhesion to a silicon substrate as the mole fraction of 2-(2-methoxyethoxy)ethyl 5-norbornene-2-carboxylate increases. 0.15 mu m line and space patterns were obtained at a dose of 10.5 mJ cm(-2) using an ArF excimer laser stepper. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.KAIST
Korea Science and Engineering Foundation Ministry of Commerce, Industry and Energ
Phase sensitive detection for mode-locked fiber laser gyroscope
No full textWe demonstrate a significant improvement in the performance of a mode-locked fiber laser gyroscope by using a lock-in amplifier. We show that the direct output of the lock-in amplifier has a desirable linear dependence on the rotation rate and is insensitive to the intensity difference between two pulses that causes phase error in the time interval measurement. Two orders of magnitude improvement is demonstrated in the longterm stability compared to that from previously reported time interval measurement
Development of the public attitude model toward nuclear power in Korea
No full textThis paper deals with the structure of public attitude towards nuclear power plants in Korea. Special emphasis is given to the issues of public acceptance in relation to perceived benefits, perceived risk, judged safety, and safety satisfaction. The national survey data of 1995 by the Korea Institute of Nuclear Safety is analyzed with a latent class model and logistic regression. The latent class model is used to construct benefit and risk factors. With these factors and safety-related variables, a public attitude model is developed by logistic regression which enables the relationships between national or local acceptance of nuclear power and explanatory variables to be quantified. The results show that the attitude structure is somewhat different by gender. Subjectively perceived risk is found to be the most influential factor for local acceptance. The odds of local acceptance with the best risk perception is about 16 times the odds with the worst perception for males and about 7.7 times for females. From the results of this analysis, it is clear that subjective satisfaction with nuclear safety is a more important factor for explaining public acceptance rather than judgment of it. These important findings should be reflected in the public acceptance improvement strategy for the nuclear power program. (C) 1998 Elsevier Science Ltd. All rights reserved
Dynamic erbium-doped fiber amplifier based on active gain flattening with fiber acoustooptic tunable filters
No full textWe describe the first demonstration of a dynamic erbium-doped fiber amplifier (EDFA) based on automatic feedback control of active gain equalizing filters. The filters are all-fiber acoustooptic tunable filters capable of generating controllable filter shapes. Wide dynamic-range gain/power control is achieved with <0.6-dB signal ripple over 30 mn in various operating conditions. We also show, by numerical simulation, an important advantage of the dynamic EDFA over a conventional EDFA in cascaded structures
Effect of a TiO2 buffer layer on the CV properties of Pt/PbTiO3/TiO2/Si structure
No full textMetal/ferroelectric/insulator/semiconductor (MFIS) capacitors were prepared by depositing PbTiO3 and TiO2 layers on Si(100) wafers at 450 and 550 degrees C using metal organic chemical vapor deposition (MOCVD). The C-V properties of the capacitors depend on the quality of TiO2 films and TiO2/Si interfaces. The TiO2 film could serve as an effective buffer layer against the Pb diffusion and provide good C-V properties as long as it was deposited at proper substrate temperature with proper thickness
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