• 연구논문집
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• s.31
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• pp.101-112
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• 2001

A Twisting machine is to twist yarns for improving yarn stiffness. After twisting yarns, the twisting machine is winding yarn at a bobbin. Traverse cam is main part of winding yarn part. In other to improve twisting machine performance and stability, improve traverse cam part. Original displacement curves of traverse cam has two problems. One is that displacement curve has a vertex point the other is that velocity curve is discontinue point. So that, in this paper proposes a modified displacement curves of traverse cam and new shape design method of the traverse cam using the relative velocity method[1]. The relative velocity method calculates the relative velocity of the follower versus the cam at a center of roller, and then determines a contact point by using the geometric relationship and the kinematical constraints. Finally, we present to compare two designed cam. One is designed using original displacement curves the other is using modified displacement curve.

• Textile Coloration and Finishing
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• v.18 no.3 s.88
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• pp.49-58
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• 2006

The purpose of this study was to examine the effect of covering yarn's twist on mechanical properties of knitted fabrics of composite yarns with single covering process. Four yarns that were used in this study: two different composite yarns made from the four kinds of cotton and functional polyester-(Poly-A) with the ratio of 52:48, and the rest two yarns are the original cotton 100% yarn and the poly-A 100% yarn. The two kinds of composite yarns, CP1 and CP2, were processed on the single covering process. CP1 was applied on the single covering process with S-800 tpm, where Poly-A was used as covering yarn and cotton was used as core yarn. CP2 was applied on the same process as CP1 except that Poly-A had been applied on the two-for-one twisting process with S-400 tpm on the previous step. Sixteen mechanical properties of all the four knifed fabrics knitted under the same knitting conditions were measured by KES-FB system with the outer knit condition. And 3D CAD dressmaking simulations, which were driven by some of the mechanical properties, were presented. The results were as follows: CP2 had high RT values with twisting of covering yarn. CP2 also had high B, 2HB values because of higher linear density. SMD was affected rather by twisting of covering yarn than by fine hair of the cotton surface. Twisting of covering yarn made it decreasing T value and increasing W value. Dressmaking 3D CAD simulations showed that there are buckling effects on CP2 because of high bending rigidity and shear rigidity.

• Textile Coloration and Finishing
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• v.18 no.1
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• pp.33-43
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• 2006

The purpose of this study was to eximine the effect of different yam twisting methods on mechanical properties and 3D CAD images of plain knitted fabrics made of composite yarns. Six yams were used in this study: four different composite yams of the six consist of acetate and functional polyester (Poly-m) with the ratio of 70:30, and the rest two are the original acetate $100\%$ yam and the poly-m $100\%$ yarn. The four kinds of composite yarns were processed in combinations of twisting processes such as interlacing, false twisting, two for one twisting, combined twisting and single covering, and the two original yams were knitted without any twisting process. Sixteen mechanical properties of all the six knitted fabrics, knitted under the same knitting conditions, were measured by KES-FB system with the outer knit condition. The results were as follows; 1) When the sample applied with the false twisting process at the temperature as high as $220^{\circ}C$, ENT, B, HB, G and RC values of samples increased which leads to increasing dimensional stability. 2) To gain the high bending and shear properties in the single covering process, selecting the core yarn with such properties is the most important factor. 3) Interlacing process effected to increase RC value. 4) False twisting process after interlacing process gave bulkiness and un-interlaced part in yam was increased SMD value. The SMD value of the kilted fabric of the composite yarn, which was put through the combined twist process, was higher than those of which simple process such as the two for one twist or the single covering process applied. In order to achieve the silk-like surface feel of knitted fabric, the sin91e covering process is recommended. 5) Examining the simulation images of the knifed fabrics of composite yarn, which were generated by the 3D CAD system based on the mechanical properties of the fabric, led that appearance could be changed as different twisting methods were applied.

• Journal of the Korean Society of Safety
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• v.27 no.2
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• pp.84-91
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• 2012

This study evaluated three forces (lifting, pushing and twisting) required to maneuver the single-wheel barrows according to handle height, width, horizontal angle and vertical angle. The four independent variables were varied in two levels. Handle height was varies in two levels : 'knuckle height (KH)' and 'KH + 0.1 ${\times}$ stature'. The two handle widths were '1.5 ${\times}$ shoulder width (SW)' and '1.75 ${\times}$ SW'. Two angles of $0^{\circ}$ and $15^{\circ}$ were used for horizontal and vertical angles. The 24 factorial design was used in the experiment. Twelve healthy male students (undergraduate and graduate) participated in the experiment. Subjects exerted three forces (pushing, lifting, and twisting clockwise) in each experimental condition. The order of 16 treatment conditions was determined randomly. Results showed that the effects of the four factors were different according to three forces. While lifting and twisting forces were higher in 'knuckle height', the pushing force was higher in 'KH + 0.1 ${\times}$ stature' (p < 0.05). Lifting and pushing forces showed higher values in the horizontal angle $0^{\circ}$ than in $15^{\circ}$. Handle width and vertical angle showed no statistically significant main effects on three forces (p > 0.05). Results of this study could be used as basic data for the ergonomic design of handle variables of one- or two-wheel barrows.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.2 s.150
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• pp.275-285
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• 2006

The purpose of this study was to examine the change of dyeing ability by K/S values, when dyed in different twisting processes and by one bath system and two bath system, to find possible ways of minimizing the color difference between cotton and polyester in composite yarn. The two types of composite yarn, which had one setting process(CP1) and two setting processes(CP2) were dyed with reactive/disperse dyes in both one bath dyeing system and two bath system. The dyeing ability according to the two different twisting processes was measured, and the values of the CP1 were higher compare to the values of CP2 in both one and two bath dyeing systems. This is because CP1 applied only one setting could shrink dyeing process at 130$^{circ}C$. This shrinkage increased the number of twists in the unit length and increased the yarn density, and this is the reason that the K/S values were measured higher than those of CP2. In wet shrinkage test, in opposition to CP2 only had 0.76$\%$ of the shrinkage rate, CP1 had 3.00$\%$ of the shrinkage rate. Also, the dyeing ability according to the two different dyeing methods was measured, and the values of CP1 and CP2 were both higher when dyed in two bath system. On the other hand, the color differences between cotton and polyester in composite yarns, were smaller for CP2 than that for CP1 and were also smaller in two bath dyeing system than in one bath dyeing system. Therefore, the ways of minimizing color difference between cotton and polyester in composite yarn are to apply enough setting in order to minimize shrinkage in dyeing process and to choose two bath dyeing system.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.281-292
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• 2014

We propose a novel cooperative guidance law design method based on the finite time disturbance observer (FTDO) for multiple near space interceptors (NSIs) with impact time control. Initially, we construct a cooperative guidance model with head pursuit, and employ the FTDO to estimate the system disturbance caused by target maneuvering. We subsequently separate the cooperative guidance process into two stages, and develop the normal acceleration command based on the super-twisting algorithm (STA) and disturbance estimated value, to ensure the convergence of the relative distance. Then, we also design the acceleration command along the line-of-sight (LOS), based on the nonsingular fast terminal sliding mode (NFTSM) control, to ensure that all the NSIs simultaneously hit the target. Furthermore, we prove the stability of the closed-loop guidance system, based on the Lyapunov theory. Finally, our simulation results of a three-to-one interception scenario show that the proposed cooperative guidance scheme makes all the NSIs hit the target at the same time.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.135-138
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• 2003

오늘날의 섬유산업은 단순히 입는다는 기능적인 면에서 탈피하여 인간의 미와 감성을 추구하는 매체로써의 역할을 요구하고 있다. 따라서 다양한 직물을 선호하는 소비자들의 욕구를 충족시켜주기 위하여 원사 자체가 점점 다양화 되어가고 있으며, 특히 합성섬유의 발명에 의해서 의류용 소재로 많이 사용되고 있다. 섬유에 감성을 부여하기 위한 방법으로 여러 가지가 있지만 최근 일본, 이태리 등을 중심으로 활발히 시도되고 있는 복합연사기술의 개발에 많은 관심이 집중되고 있다.[7] (중략)

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.679-682
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• 2008

The particle which has two different characteristics on both sides is called Janus particle which is emerging as a key material in microscale transport systems. For example, if one hemisphere has polarity and the other does not, then nonpolar sides would attract each other so that a complex cluster is formed. Thus, this fascinating material can be used as an element of twisting ball panel display, complex micro-scale clusters, drug delivery unit, and active detecting beads. The keywords in developing Janus particle are size and uniformity. Former researches solved uniformity but downsizing still remains a problem. There are three methods to generate small size particles in microchannels: co-flowing, cross-flowing, and elongational flows. In this research, we generate Janus particles smaller than 10-${\mu}$m in diameter using elongational flow in microchannels. And we use UV initiator with Hydrogen UV source to solidify micro size particles. One hemisphere of the particle is coated with rhodamin for visualization.

• Journal of KSNVE
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• v.5 no.3
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• pp.327-335
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• 1995

The study deals with the vibration of a beam whose flexural and centroidal axes are not coincident. The elementary bending-twisting theory is employed to derive the equation of motion, in which the effects of rotary inertia are added to the bending displacements and the effects of warping are added to the twist. Bending translation is restricted to one direction so that one bending equation is used instead of two. The equations of motion are solved by using the boundary value problem. The exact natural frequencies are fund from the frequency equation, which is obtained from the condition that the homogeneous system of algebraic equations representing the spatial solution shall not yield a trivial solution. The orthogonal conditions are established, and the principal mode equations of forced vibration are derived. As an example, the cantilevered beam is chosen and the first some natural frequencies and their modal shapes are found.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.2
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• pp.8-13
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• 2007

The purpose of this study is to reduced the weight of ladder boom and to improve the manufactor process by the section modification. The Conventional model consists of integral section stiffener, while the proposed model consists of truss type stiffener to reduce the weight of ladder boom and wind effector. In the two analysis models, one is based on the single boom, and the other is based in the coupling model of two booms. We present the analysis results for the case when applying the weight, bending and twisting moment and wind pressure. Finally, a comparison between these results is presented to show the performance of our method.