• Fibers and Polymers
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• v.7 no.3
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• pp.305-309
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• 2006

This research studies the factors which influence the tensile strength of tire cords. Five yam samples are made by changing the spinning conditions and viscosity to get various physical properties. Different twisting methods are introduced and the yams are twisted under different processing conditions for each twisting process. With the experimental results, various analyses are performed to find the important factors in retaining strength after the twisting process. SEM and optical microscopic photographs are taken along with some measurements to assist the analysis.

• Journal of the Korean Society of Clothing and Textiles
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• v.25 no.5
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• pp.891-900
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• 2001

The purpose of this study were to evaluate the physical properties and dyeability of cellulase and alkali(NaOH, KOH) treated ramie/man-made fiber mixture fabrics. The mixture fabrics were plain weave made by rayon and polyester fiber as warp yarn, and ramie as weft yarn. The crease resistance, drape, tensile strength, and water absorbancy were measured for test fabrics. The K/S value of dyed fabrics were calculated using color difference meter. Also colorfastness to washing and sunlight of dyed fabrics were evaluated. The results obtained from this study were as follows: Thickness and weight per unit area of alkali treated two mixture fabrics(rayon/ramie, polyester/ramie) increased compared to those of untreated fabrics, but cellulase treated fabrics did not changed a little. And alkali treated rayon/ramie mixture fabrics showed more change than polyester/ramie mixture fabrics on the thickness and weight. Tensile strength and water absorbancy of cellulase treated fabrics decreased compared to those of untreated, but crease resistance increased. Crease resistance, tensile strength(warp direction), water absorbancy and drape of NaOH treated rayon/ramie mixture fabrics decreased compared to those of untreated, but tensile strength(weft direction) increased. Water absorbancy and drape of NaOH treated polyester/ramie mixture fabrics decreased compared to those of untreated, but crease resistance and tensile strength(weft direction) increased. Tensile strength of KOH treated two mixture fabrics increased compared to that of untreated, but water absorbancy and drape decreased. Total hand of cellulase and alkali treated rayon/ramie mixture fabrics was improved compared to untreated. Dyeability of treated mixture fabrics was increased compared to untreated.

• 연구논문집
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• s.27
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• pp.127-139
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• 1997

Two-for-one twister is a kind of textile machine and makes special fancy yarn which is twisted two times per one revolution in order to increase tensile strength and wear resis-tance of yarn. Spindle mechanism has to be stable and continuous motion in high speed revolution, and then optimal design is necessary to analyze dynamic characteristics of spindle unit. Spindle unit is consist of blade and rotary disc that are cylindrical body of revolution. For analysis of the dynamic characteristics of spindle unit, transfer matrix method is used and a numerical code SPINDLE also. Torsion and natural bending frequency of the spindle unit are examined. Its displacement mode is studied in function of variable revolutions.

• Composites Research
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• v.15 no.6
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• pp.30-37
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• 2002

A stiffness model has been proposed to predict elastic constants of twisted yam composites. The model is based upon the unit cell structure, the coordinate transformation, and the volume averaging of compliance constants for constituent materials. For the correlation of analytic results with experiments, composite samples of various yam twist angles were tested, and strength and Young's modulus under tensile, compressive, and shear loading have been obtained. The sample was fabricated by the RTM process using glass yarns and epoxy resin. The correlations of elastic constants showed relatively good agreements. The model provides the predictions of the three-dimensional engineering constants, which are valuable input data for the analytic characterization of textile composites made of twisted yam.

• Fibers and Polymers
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• v.7 no.3
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• pp.295-304
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• 2006

High-bulk worsted yams with different shrinkable and non-shrinkable acrylic fibers blend ratios are produced and then single jersey weft knitted fabrics with three different structures and loop lengths are constructed. The physical properties of produced yams and compression properties of produced fabrics at eight pressure values (50, 100, 200, 500, 1000, 1500 and $2000 g/cm^2$) were measured using a conventional fabric thickness tester. Then, weft-knitted fabric compression behavior was analyzed using a two parameters model. It is found that at 40 % shrinkable fibre blending ratio the maximum yam bulk, shrinkage, abrasion resistance and minimum yarn strength are obtained. It is also shown that high-bulk acrylic yarn has the highest elongation at 20 % shrinkable fibre blend ratio. The statistical regression analysis revealed that the compression behavior of acrylic weft-knitted fabrics is highly closed to two parameter model proposed for woven fabrics. It is also shown that for weft-knitted structure, there is an incompressible layer (V') which resists against high compression load. Acrylic weft-knitted fabrics with knit-tuck structure exhibit higher compression rigidity and lower softness than the plain and knit-miss structures. In addition, at 20 % shrinkable fibre blend ratio, the high-bulk acrylic weft-knitted fabrics are highly compressible.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.330-338
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• 2016

Impregnation of shear-thickening fluid(STF) into high-strength fabrics makes a considerable improvement on the ballistic performance of fabric armors. Understanding dissipation augmentation due to shear thickening effects on yarn-yarn and yarn-projectile friction is of great importance in liquid armor research. This paper takes a shearthickening effect into account in numerical simulations by using a velocity-dependent friction model. Impact simulations were performed to validate the friction model as well as to evaluate the ballistic performance of STF-fabrics. Impact simulations on neat fabrics were also conducted to provide baseline results for comparison.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.939-941
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• 2017

The use of composites is increasing for lightweight aerospace structures. Among these structures, the ring frame and the parts of the projectile body are mainly made of a fiber reinforced composite material which is less susceptible such as delamination to structural damage. As the use of fiber reinforced composites increases, interest in modeling efficient methods of stiffness and strength is increasing. This paper predict the mechanical strength according to the repeating unit cell(RUC) of the 2-D triaxial braided composites of fiber reinforced composites. Yarn slice definition, incremental approach and stiffness reduction model were used as strength prediction. Finally, the results of strength prediction are verified by comparing with experimental data of 2-D triaxial braided composites specimens.

• Fibers and Polymers
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• v.7 no.3
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• pp.310-316
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• 2006

In this article, an attempt has been made to explain the failure mechanism of spun yams. The mechanism includes the aspects of generation and distribution of forces on a fibre under the tensile loading of a yam, the free body diagram of forces, the conditions for gripping and slipping of a fibre, and the initiation, propagation, and ultimate yam rupture in its weakest link. A simple mathematical model for the tenacity of spun yams has been proposed. The model is based on the translation of fibre bundle tenacity into the yam tenacity.

• Textile Coloration and Finishing
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• v.31 no.4
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• pp.288-297
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• 2019

The specimens were heat treated at 180℃, 190℃, 200℃, 210℃ and 220℃ to observe the change of the physical properties of the double raschel pile fabric. The density, tensile strength, weight, elongation, dyeing characteristics, fabric surface morphology and cross sectional shape were observed by heat treatment temperature. Compared with untreated samples, weight, density and tensile strength were increased with increasing heat treatment temperature. No increase was observed at 220℃. In the case of elongation, it increased to 190℃ but thereafter it could not be observed. In the case of uprightness of brushed hair, it was observed that the gap between the yarns was narrowed and the density was increased and the straightness of the yarn and pile yarn was improved by widening the heat treatment temperature. As a result, it was observed that the uprightness was remarkably improved and the bulky properties was increased. It was also observed that the increase of the dyeability was observed with increasing the heat treatment temperature.

• Advanced Composite Materials
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• v.17 no.3
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• pp.225-233
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• 2008

The analysis in this paper is focused on the pattern of mixing of filaments over a cross-section of hybrid yarns according to different combinations of reinforcement and matrix filament yarns through microscopic view. The volume content of filament in hybrid yarn cross-section was maintained at 50% for both reinforcement and matrix, and the hybrid yarns count at 600 tex throughout the experiments. It was observed from the experiments that diameters of reinforcement and matrix filaments have strong effects particularly on the pattern of mixing of filaments over a cross-section of hybrid yarns such that the hybrid yarns with more or less equal diameters of reinforcement and matrix filaments showed considerably even distributions over the hybrid yarn cross-section. This paper also investigates the possibility of hybridizing carbon/aramid, carbon/glass and aramid/glass matrices through the commingling process. In the experiment, several process parameters were selected and they include pressure, yarn oversupply-rate and different nozzle types. As a result of these experiments, it was concluded that the hybridized materials show better performance than individual reinforced filament yarns in terms of mechanical properties. For small tensile forces, the carbon/glass/matrix combination turned out to be good enough for general purpose applications.