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The permitted limit, ±12%, of the change in solid contents based on ASTM C 494 as an interim standard in Korea Expressway Corporation, can not reflect the kind of chemical admixture and the characteristics of solid content so that it differed depending on the admixture types. In this study, effect of cement concrete quality was investigated by solid changes which can be used chemical admixtures acceptance criteria. As a result of an evaluation of a change in the quality of concrete due to solid content, since Ligno-sulfonate based (LG) had a low water reducing ratio, the range of the change in solid content was great while Naphthalene sulfonated based (PNS) and Poly-carboxylate based (PC) High Range Water-reducing Admixtures (HRWR) had a high water reducing ratio, the permitted limit of the difference in solid content currently used as the acceptance criterion should be readjusted. As a result, it is found that the acceptable range must be managed within 10% and 5% when the solid contents less than 25% and more than 25%, respectively.

We present a theoretical and experimental analysis of the polarization dependence of a two-mode-fiber acoustooptic device, taking into account the residual stress in the fiber and the ellipticity of the core. We successfully demonstrate the suppression of the polarization dependence by relieving the residual stress, using thermal annealing.

We report an unusually large birefringence modulation in fiber-optic phase modulators formed with cylindrical piezoelectric transducers when driven at a few hundred kilohertz. The magnitude of the birefringence modulation is a strong function of modulation frequency. A simple model is used to explain the phenomenon, and the theoretical predictions agree well with the experimental results.

We present a new method to flatten the gain profile of optical amplifiers; inserting an optical isolator in the middle of an Er doped fiber amplifier (EDFA). A flat gain bandwidth of more then 30 nm was experimentally obtained by this method. This is more simple and effective than other gain flattening filter methods.

An anti-reflection coated GaAlAs laser diode was used as a gain medium in a mode-locked fiber laser gyroscope to obtain stable mode-locked optical pulses without gain competition. The time intervals between the pulses could be measured with much improved accuracy using an electronic counter. The rms noise equivalent rotation rate was 3.4 deg/hr/(root)Hz and the long-term drift was less than 200 deg/hr.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A semiconductor laser amplifier is used as a gain medium in a mode-locked fiber laser gyroscopes to obtain stable mode-locked optical pulses without gain competition. The pulse intervals could be measured with much improved accuracy as a function of rotation rate. The rms noise equivalent rotation rate was measured to be 0.04deg/sqrt(h).

A simple and reliable all-fiber-optic component for a first-order polarization mode dispersion compensator is presented and tested in a 10-Gbit/s transmission system. The proposed component incorporates tunable differential group delay (DGD) provided by several pieces of polarization maintaining (PM) fibers of different DGD that were spliced together with short lengths of single-mode fibers between them. The total DGD of the compensator is determined by the alignment of fast and slow axes of the PM fiber sections. Applying this component as a first-order polarization mode dispersion (PMD) compensator, we demonstrate that a component with seven pieces of PM fiber segments could possibly compensate the first-order PMD up to 63.5 ps with 1-ps steps and a switching time of 300 ms. We also optimize the number of PM fiber sections in this component for a first-order PMD compensation in a 10Gbit/s system based on experimental results.

We 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 0.06deg/ radicalh. The long-term drift of the gyroscope signal was reduced to 100deg/ radicalh after a polarizer was inserted into the laser cavity formed with a polarization-maintaining fiber.

We investigated the polarization characteristics of a mode-locked fiber laser gyroscope (MLPLG) formed with a Nd-doped fiber as an optical gain medium and a Sagnac loop mirror. The output pulse patterns and the polarization states were found to be determined by fiber birefringence in the different sections of the MLPLG. We describe the conditions for the MLPLG to operate with automatic reciprocity leading to the possibility of phase-error-free operation.