• Fibers and Polymers
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• v.3 no.1
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• pp.18-23
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• 2002

The structure development and dynamic properties of fibers produced by high-speed spinning of P(EN-ET) random copolymers were investigated. The as-spun fibers were found to remain amorphous up to the spinning speed of 1500 m/min, and subsequent increases in speed resulted in the crystalline domains containing primarily $\alpha$ crystalline modification of PEN. The f modification was not found up to spinning speeds of 4500 m/min. On the other hand, annealing of constrained fibers spun at the 2100 m/min at 180,200, and 240^{\circ}C$ exhibited $\beta$-form crystalline structure, while the annealed fibers spun in 600-1500 m/min range exhibited dominantly $\alpha$-form. However $\beta$-form crystals disappeared above the spinning speed of 3000 m/min. With increasing spinning speeds from 600 to 4500 m/min, the storage modulus of as-spun fibers increased continuously and reached a value of about 10.4 spa at room temperature. The tan $\delta$curves showed the $\alpha$-relaxation peak at about 155-165^{\circ}C$, which is considered to correspond to the glass transition. The $\alpha$-relaxation peaks became smaller and broader, and shift to higher temperatures as the spinning speed increases, meaning that molecular mobility in the amorphous region is restricted by increased crystalline domain.

• Structural Engineering and Mechanics
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• v.51 no.6
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• pp.1047-1065
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• 2014

The article presents the methodology for finding material damping capacity at higher frequency and at relatively lower amplitudes. The Lamb wave dispersion theory and loss less finite element model is used to find the damping capacity of composite materials. The research has been focused on high frequency applications materials. The method was implemented on carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) plates. The Lamb waves were generated using ultrasonic pulse generator setup. The hybrid method has been explored in this article and the results have been compared with bandwidth methods available in the literature.

• Journal of Power System Engineering
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• v.19 no.3
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• pp.5-10
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• 2015

Femtosecond laser machining has been applied for creating a sensor function in silica glass optical fibers. Femtosecond laser pulses make it possible to fabricate micro structures in processed regions of a very thin glass fiber line because femtosecond laser pulses can extremely minimize thermal effects. With the laser machining to optical fiber using a single shot of 210-fs laser at a wavelength of 800 nm, it was observed that a processed region surrounded a thin layer which seemed to be a hollow cavity monitored by scanning electron microscopy (SEM). This study aims at a theoretical investigation for the processed region by using a numerical analysis in order to embed sensing function to optical fibers. Numerical methods based finite element method (FEM) has been used for an optical waveguide modeling. This report suggests two types modeling and describes a comparative study on optical losses obtained by the experiment and the numerical analysis.

• Structural Engineering and Mechanics
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• v.63 no.5
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• pp.597-605
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• 2017

Our work aims to analyze using the finite element method the evolution of the stress intensity factor (SIF) parameter K of three laminated folded plates stacks [$+{\alpha}$, $-{\alpha}$], made of the same epoxy matrix and different reinforcement fibers (boron, graphite and glass). Our results show that the angle of orientation of the boron/epoxy composite has no great influence on the variation of the parameter KI. Compared to composite graphite/epoxy and glass/epoxy, the laminated composite boron/epoxy reduces more the SIF KI in the middle of the plate for angles $0^{\circ}{\leq}{\alpha}{\leq}30^{\circ}$.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.12-18
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• 2019

The protective double layer polymer coatings on silica optical fibers are realized by wet-on-wet liquid coating process and they play an important role in final quality of mass produced optical fibers. This numerical study aims to analyze the effects of secondary coating die design parameters by employing two dimensional axisymmetric model of coating cup and coating die geometry and computational fluid dynamics simulations which include temperature dependent viscosity of polymer coating liquids and viscous dissipation heating. Under high speed fiber drawing conditions and pressurized coating liquid supply, the effects of converging die angle are investigated in order to appreciate the change of coating liquid flow patterns such as flow recirculation zone near coating die as well as primary and secondary coating layer thicknesses. The auxiliary coating die to converging coating die is also tested and the results find that this concept is advantageous in achieving stable double layer coatings on silica glass fiber.

• Textile Coloration and Finishing
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• v.31 no.1
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• pp.42-47
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• 2019

In this study, the effects of surface treatment of bamboo fiber on the physical properties of polypropylene(PP)/glass fiber(GF)/Bamboo fiber(BF) composite for engine cover were investigated. PP, GF and BF were fixed at 40%, 40% and 20% and the surface of bamboo fibers were treated to 0.5, 1.0 and 2.0% as an acid and alkali solution. PP/GF/BR composites using surface treated bamboo fibers were prepared and their tensile strength, bursting strength and impact strength were measured by universal testing machine(UTM). The composites with alkali treated bamboo fiber showed better mechanical properties than the acid treated composites. It was checked that the optimum alkali content was at 1.0% from the results of mechanical properties. The effect of surface treatment on the mechanical properties was confirmed by SEM images of fractured surface.

• Textile Coloration and Finishing
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• v.14 no.3
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• pp.11-18
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• 2002

The preparations of deodorizing fibers using $\textrm{TiO}_2$ have been investigated. $\textrm{TiO}_2$ is known to be an excellent photocatalyst for the degradation of organic and inorganic contaminants in water. $\textrm{TiO}_2$ catalyst have been supported on the glass fiber by a dip-coating procedure. The resulting materials have been characterized by XRD and SEM. The immobilized catalysts were tested in the photocatalytic degradation of $\textrm{NH}_3$, $\textrm{CH}_3\textrm{SH}$ and $\textrm{CH}_3\textrm{CHO}$. The deodorant activity(D.A.) of these deodorizing fibers was measured by chromogenic gas detector tubes. The efficient deodorant activity results have been achieved through the increase of $\textrm{TiO}_2$ sol concentration.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.2
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• pp.13-21
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• 2002

A new method for measuring fiber length and fiber coarseness was developed using image analysis technique. Measured fibers were transferred to a glass slide on a filter paper placed on a wire of the laboratory paper machine. After staining the fibers on the slide, mean fiber lengths and coarseness were measured by a commercial image analysis software, named KS400. The resultant data obtained from the image analysis displayed a close correlation with those from FS-200 and also showed excellent reproducibility as well as those from FS-200. The length of synthetic fibers over 10 mm long could be readily measured by this new analysis technique. Finally, a substantial improvement in precision for measuring fiber length and coarseness was made with less operator's effort for a given time.

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.362-363
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• 2004

• Proceedings of the Korean Fiber Society Conference
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• 1993.06b
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• pp.599-604
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• 1993