• Proceedings of the Korea Concrete Institute Conference
• /
• 1990.04a
• /
• pp.5-10
• /
• 1990

There are two main methods in reinforcing cements with glass fibers : spray-suction and premixing method. But GRC have been mostly studied by spray technique. In order to develop GRC made by premixing method, in this paper, the influence of glass fiber length, volume content and curing conditions upon the compressive, direct tensile and bending strengths of composites fabricated by a premixing method, were investigated. According to the test results, although it was difficult to obtain perfectly uniform distribution of fibers in GRC Pannel, it was found that tensile strength of cements with glass fiber was improved 2~5 times and flexural strength 4 times compared to conventional cement mortar upto fiber length 35 mm, volume content 4%.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.32 no.2
• /
• pp.51-57
• /
• 2000

Cylinder machine usually gives more fiber orientation than fourdrinier and has limitation in machine speed because of fiber wash-off caused by centrifugal force when machine speed increases. This study aimed for the improvement of paper formation and productivity by setting an apron in vat inlet and by adjusting mould water head. Improvement of formation and increase of machine speed were achieved, which ultimately improve productivity. Installing an apron successfully decreased fiber wash-off. Fiber orientation and two-sideness of ash distribution became less severe. The proper adjustment of water head inside the cylinder mould proved to be an important factor not only in paper formation but also in decreasing paper two-sideness.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.630-632
• /
• 2018

The compensation characteristics of the distorted WDM channels compensated for by dispersion management (DM) and optical phase conjugation in the long-haul (50 fiber spans ${\times}$ 80 km) transmission link with the randomly distributed single mode fiber (SMF) length and residual dispersion per spans (RDPS) for implementing of the flexible link configuration are investigated.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.36 no.1
• /
• pp.61-66
• /
• 2004

Bleached chemithermomechanical pulp (BCTMP) was produced from CTMP of Betula maximowicziana Regel by two staged ozone-hydrogen peroxide bleaching in order to improve the optical properties of high yield pulp. This pulp was used for the evaluation of optical properties improvement, chemical characteristics of lignin in fiber and the relationship between lignin and optical properties in fiber cell wall. Hydrogen peroxide treatment improved the brightness, but the post color number (PC No.). There was little improvement on optical properties by ozone treatment, but this could be improved more by using two staged ozone-hydrogen peroxide bleaching. The hydrogen peroxide treatment did not make any change on chemical characteristics of lignin in cell wall, but by ozone treatment, it was found that the non-aromatic conjugated structure was existed in the surface of cell wall, but this could be removed by hydrogen peroxide treatment in two staged ozone-hydrogen peroxide treatment. Therefore, the optical properties was significantly improved, due to the removal of non-aromatic conjugated structure.

• Structural Monitoring and Maintenance
• /
• v.1 no.2
• /
• pp.173-182
• /
• 2014

We describe the application of a distributed optical fiber sensor based on stimulated Brillouin scattering, as an integrated system for safety monitoring of railway infrastructures. The strain distribution was measured statically and dynamically along 60 meters of rail track, as well as along a 3-m stone arch bridge. We show that, gluing an optical fiber along the rail track, traffic monitoring can be performed in order to identify the train passage over the instrumented sector and determine its running conditions. Furthermore, dynamic and static strain measurements on a rail bridge are reported, aimed to detect potential structural defects. The results indicate that distributed sensing technology represents a valuable tool in railway traffic and safety monitoring.

• The International Journal of Costume Culture
• /
• v.5 no.2
• /
• pp.53-65
• /
• 2002

Morphology of polyester fiber was physically modified by solvent treatment. PET fiber was treated with N,N-dimethylformamide (DMF) at 100, 120, $140^{circ}C$ for 10 minutes without tension. The structural changes in the morphology of DMF-induced modified PET fiber were FTIR and SEM analysis. Also dyeing behavior of DMF-treated polyester fibers with various disperse dyes was studied to detect changes of amorphous area in fine structure. DMF treatment resulted in increases in total void content, degree of crystallinity, trans isomer content, chain folding, segmental mobility and molecular packing, but it resulted in decreases in amorphous orientation, intermolecular forces and individual void size through longitudinal shrinkage, lateral welling and removal of oligomers. Void-size distribution could be estimated from the dye uptake with various sizes of disperse dyes. In contrast to the large increases in dye uptake with small dye molecules, there is no and little dye uptake with the bulkiest dye, which means that void size is bigger or smaller than the volume of each dye. Diffusion rates of dye molecules showed increases. This dyeing study revealed that the disperse dyeing is very effective method for characterizing the internal morphology of polyester fiber.

• Carbon letters
• /
• v.23
• /
• pp.17-21
• /
• 2017

Polyurethane (PU) nanofibers containing graphene oxide (GO) and Ag doped functionalized reduced graphene oxide (Ag-RGO) were successfully prepared via the electrospinning technique. The uniform distribution of GO sheets along with Ag nanoparticle in the nanofibers was investigated by scanning electron microscopy and the elemental mapping technique. X-ray diffraction and thermal gravimetric analysis verified the presence of GO and Ag in the bicomposite nanofibrous mats. Antibacterial tests against Escherichia coli demonstrated that the addition of GO and Ag-RGO to the PU nanofiber greatly enhanced bactericidal efficiency. Overall, these features of the synthesized nanofibers make them a promising candidate material in the biomedical field for applications such as tissue engineering, wound healing, and drug delivery systems.

• Journal of the Korean Society for Railway
• /
• v.7 no.4
• /
• pp.319-325
• /
• 2004

In this study, analysis and design programs of bending of RC beams strengthened with fiber sheets are developed by using Visual Basic Language. The program consists two groups, ultimate strength method and nonlinear flexural analysis method. Ultimate strength method regards concrete compressive stress as a rectangular stress block and do not consider tensile stress of concrete and load-deflection curves. On the other hand, nonlinear flexural analysis considers tensile stress of concrete, load-deflection curves, state of stress distribution and failure strain of strengthening material. Also, the analysis method used in this study regards nonlinear flexural stress as compressive stress of concrete. This program can be a good tool for determining the bending strength of strengthened RC beams and estimating the amount of fiber sheets for practical use.

• Korean Membrane Journal
• /
• v.3 no.1
• /
• pp.59-68
• /
• 2001

Unlike existent field flow fractionation, new method, osmotic sink field flow fractionation is introduced and used ultrafiltration hollow fiber membranes as separation channel. This hollow fiber osmotic sink field flow fractionation is called HF-OSFFF. A theory that describes the retention, relaxation, resolution, plate number for the system, has been developed and experimentally verified by separation model of po1ystyrene latex beads. At external field, it is measured that radial flow rates change according to various concentrations of PEG solutions. Concentration of PEG solution vs. radial flow rate is a linear relation. For diameter distribution of unknown polymer sample, HF-OSFFF compared with the commercial capillary hydrodynamic flow fractionation (CHDF).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.1
• /
• pp.57-63
• /
• 1991

In this paper, propagation characteristics of W-type single mode fiber with dual shape core is investigeted theoretically. Design parameters of DSC(dual shape core) W-type single mode fiber with very low dispersion over a wide wavelength range are computed using scalar approximation. The results have larger core radius and stronger confinement for mode field distribution in core than conventional W-type fiber with single shape core.