• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.67-70
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• 2010

Spandex yarn requires a twisting process during winding and unwinding processes at the textile industry. The air-twist nozzle is widely used as part of the winding and unwinding. This paper describes computational approach to design the geometry of the air-twist nozzle. The nozzle has circular yarn-channel and the air-inlet which is perpendicularly connected to the yarn-channel with yarn-loading slit. The air-inlet of the nozzle is designed while measurements of the yarn-channel are fixed. The airflow inside the air-twist nozzle is simulated by using Computational Fluid Dynamic model. The Ansys CFX was used to perform steady simulations of the airflow for the air-twisting process. The vortical structure and the airflow pattern such as velocity streamline, vorticity, velocity of the air-twist nozzle are discussed. Computational results are compared with experimental results in this paper.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.877-881
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• 2005

In this paper, a novel method for analyzing a textile fabric structure is proposed to segment each yarn of the textile fabric from voxel data made out of its X-ray computed tomography (CT) images. In order to segment the each yarn, directions of fibers, of which yarn consists, are firstly estimated by correlating the voxel with a fiber model. Second, each fiber is reconstructed by clustering the voxel of the fiber using the estimated fiber direction as a similarity. Then, each yarn is reconstructed by clustering the reconstructed fibers using a distance which is newly defined as a dissimilarity. Consequently, each yarn of the textile fabric is segmented from the voxel data. The effectiveness of the proposed method is confirmed by experimentally applying the method to voxel data of a sample plain woven fabric, which is made of polyester two folded yarn. The each two folded yarn is correctly segmented by the proposed method.

• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.93-97
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• 2005

Air interlacing serves to protect the yarn against damage, strengthens inter-filament compactness or cohesion, and ensures fabric consistency. The air interlacing nozzle is used to introduce intermittent nips to a filament yarn so as to improve its performance in textile processing. This study investigates the effect of interlacing nozzle geometry on the interlacing process. The geometries of interlacing nozzles with multiple air inlets located across the width of a yarn channels are investigated. The basic interlacing nozzle is the yarn channel, with a perpendicular single air inlet in the middle. The yarn channel shapes are cross sections with semicircular or rectangular shapes. This paper presents three doubled sub air inlets with main air inlet and one of them is slightly inclined doubled sub air inlets with main air inlet. The compressed air coming out from the inlet hits the opposing wall of the yarn channel, divides into two branches, flows trough the top side of yarn channel, joins with the compressed air coming out from the sub air inlet and then creates two free jets at both ends of the yarn channel. The compressed air moves in the shape of two opposing directional vortices. The CFD-FASTRAN was used to perform steady simulations of impinging jet flow inside of the interlace nozzles. The vortical structure and the flow pattern such as pressure contour, particle traces, velocity vector plots inside of interlace nozzle geometry are discussed in this paper.

• Fibers and Polymers
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• v.5 no.3
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• pp.182-186
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• 2004

The effect of braid construction parameters on yarn cross-sectional shape is presented in this paper. The location of the yam within the braid unit cell is quantified by a compaction factor. A range of braided fabrics were produced and optically measured for actual yarn cross-sectional shape. A comparison of the theoretical and experimental values shows good correlation. Design curves can be produced with the developed model to allow selection of appropriate braid process parameter to create yarns with desired cross-sectional geometries.

• Textile Coloration and Finishing
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• v.21 no.3
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• pp.43-48
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• 2009

This paper surveys the mechanical properties of nylon high tenacity coarse yarn and fabric for military and technical textiles. For this purpose, 6 kinds of yarns and 2 kinds of fabrics are prepared. The yarn physical properties such as yarn count, thermal shrinkages, and tensile properties are measured and discussed with the characteristics of the domestic and imported yarns. And, the physical and mechanical properties of these fabrics are also measured and discussed with the usage of these fabrics in the military and technical textiles fields. Hereafter, the differences of physical properties between domestic and foreign yarn specimens for high functional military and technical fabrics are estimated through this study.

• Fibers and Polymers
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• v.6 no.1
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• pp.72-78
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• 2005

The impact of fiber friction, yarn twist, and splicing air pressure on mechanical and structural properties of spliced portion have been reported in the present paper. The mechanical properties include the tensile and bending related properties and, in the structural properties, the diameter and packing density of the splices are studied. A three variable three level facto­rial design approach proposed by Box and Behnken has been used to design the experiment. The results indicate that there is a strong correlation between retained spliced strength (RSS) and retained splice elongation (RSE) with all the experimental variables. It has been observed that RSS increases with the increase in splice air pressure and after certain level it drops, whereas it consistently increases with the increase in yarn twist. The RSE increases with the increase in both fiber friction and yarn twist. It has also been observed that the yarn twist and splicing air pressure have significant influence on splice diameter, percent increase in diameter and retained packing coefficient, but the fiber friction has negligible influence on these parame­ters. Yarn twist and splicing air pressure has a strong correlation with splice flexural rigidity, where as poor correlation with retained flexural rigidity.

• Textile Coloration and Finishing
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• v.16 no.3
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• pp.31-38
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• 2004

Polyester fabrics, which is a major product in Daegu and Kyungbuk district, recently have a frequent warp streak phenomenon of sizing textiles for peach skin. So, this paper intensively focuses on the analysis of finding causes of poor products which may be produced in the process of sizing. Depending on the changes of sizing yarn's physical characteristic varying on sizing conditions, results of the research are as followed. 1. Sizing add-on rate, following tension changes of originally supplied yarn in sizing, does not fluctuate until 30g sizing tension, but marks high on the increase of sizing speed. 2. Sizing add-on amount increases approximately by 2.5% when interlacing pressure is raised from 1.5kg/$cm^2$ to 3.5kg/$cm^2$ at $130^{\circ}C$ sizing temperature. 3. Following the increase of sizing tension from 10g to 50g, boiling shrinkage rate of desizing yarn changes approximately from 7% to 11%. But the more sizing temperature and speed increases, the bigger the change rate becomes. 4. The thermal stress of desizing yarn is sensitively influenced by sizing tension in the sizing degree of above $130^{\circ}C$. 5. The deviation rate of sizing yarn's initial modulus value, which is influenced by air pressure in interlacing raw yarn, marks the highest at 40g and 50g strength.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.95-98
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• 2003

In woven or knitted preforms for composites, the yams are often twisted for avoiding damage due to the contact with the textile machine elements. When the preforms of twisted yams are used in carbon/carbon composites, the thermal conductivity of the composites varies depending upon the degree of the yarn twist. This paper presents a thermal conductivity model of spun yarn composites. The thermal-electrical analogy and the averaging technique have been adopted in this analysis. The model prediction has been correlated with experimental results in order to confirm the model predictability. Parametric study has also been conducted to examine the effect of the yam twist on the thermal conductivity of spun yarn composites.

• Fibers and Polymers
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• v.7 no.2
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• pp.213-216
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• 2006

The effect of cashmere yarn twist, knitted fabric density, and cashmere properties on pilling rates of cashmere knitted fabric is investigated in this paper. The experimental results show that yarn twist and fabric density have little influence on pilling rates of cashmere knitted fabric for yarn 38.4 tex/2 when yarn twist varies from 234 T/m to 272 T/m, and the fabric density is 9.7, 10.7, and 11.2 yarns/inch, respectively. The length of cashmere fiber, in particular less than 7.5 mm, is responsible for the pilling rates of cashmere knitted fabric based on optimal scaling regression analysis.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.77-78
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• 2003

The surface evenness and texture of textile products are closely related with the irregularity of yarn thickness which has an important role to influence the quality and the process efficiency. For measuring yam thickness the capacitive method is known to dominate the market, delivering results that are in a close relation with the mechanical properties of yarn, while the optical method offers information that seems related rather with the apparent quality of yarn. If a thin light beam is applied for the optoelectrical measurement, it is very possible that this method can provide us with important information which is not obtainable from the capacitive type measurement. This paper reports the results of a study about the yarn thickness and its variation on the basis of a new measurement system using a laser slit beam. Analysis of the new system confirms that we can extract new information on the yarn irregularity ranging into much short wavelengths. Even the visual shade created by the yam doubling and twisting can be measured and represented well. Depending on the yam types, the thickness measurements show their own characteristics.