정상상태 집속체 유동계의 동역학적 특성

허유,김종성,Huh You,Kim Jong Seong 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.6

Drawing is a mechanical operation that changes the material thickness by using the speed difference between the feeding and delivery devices. When the material is in the form of a bundle or bundles made of staple fibers, this attenuation operation is called 'bundle drawing' or g'draftingg'. Drafting is being used widely in manufacturing staple yarns, which is indispensable for the textile industry. However, the bundle processed by this operation has more or less defects in the evenness of linear density. Such irregularities cause many problems not only for the product quality but also for the efficiency of the successive processes. In this research, a mathematical model for the dynamic behavior of the bundle fluid is set up on the basis of general physical laws using physical variables, i.e. linear density and velocity in the dynamic state of the bundle processing. The conservation of mass and the momentum are applied, while the movement of individual material is taken into account. The constitutive model relating the surface force to the deformation of bundle is given, considering a representative bundle movement. Then, a fundamental equation system is simplified in a steady state, which could delineate the characteristics of the process dynamics. On the basis of the simplified model, simulation is performed, and the results are confirmed by experiments. This study shows that the bundle fluid, in drafting operation, can have a jerk at the exit, when the model parameters representing inter-fiber friction and velocity variance of constituent fibers are adjusted to the experimental results. Even at low draft ratios, the bundle can break, if the parameters are not maintained adequately by controlling the process conditions.

제직시스템에서의 속도변화에 대한 위사밀도의 동적 응답 (I)

허유,류운영,우제린,Huh, You,Ryu, Woon-Young,Woo, Jae-Lin 한국섬유공학회 1991 한국섬유공학회지 Vol.28 No.11

Factors affecting fabric quality are yarn, weaving machine and men. Among them the weaving machine and men can be controlled in the weaving Process. Most of fabric defects result from the yarn, the weak points of which cause the discontinuities in the machine operation responsible for the endbreakages. The interruption in production can be reduced by an optimal operation of weaving machines, but the cause of endbreakages can not be completely eliminated. The places where the machine stopped and restarted leave streaks on the fabrics, which result in the fabric defects. These defects, so called stop marks, lead to the irregularity of weft density This paper deals with relationship between the change in weft density and the weaving interruption. The weft density change, the stop mark, was measured in terms of pickspacing and the mode of weaving interruption determined by applying different forms of speed variations. The results show that the weft density change is mostly influenced by the rate of speed variation. The initial loading on the warp yarns is independent of the total weft density change, but it is responsible for the distribution of the weft density irregularity.

직선운동을 하는 직립진자의 진동 제어

허유,김형범 경희대학교 산학협력기술연구원 2000 산학협력기술연구논문집 Vol.6 No.-

In textile processing various automatic transfer systems are being used for transportations of the textile materials and packages. For roving bobbins, lap bobbins, cheese bobbins, materials for apparel manufacturing, etc. the overhead rail/trolley transfer system is efficiently taken advantage of due to the simple structure and construction flexibilities for transport route. From the structural point of view the overhead rail/trolley transfer system consists of two parts, namely overhead rail and trolley. The trolley is the carrier of the textiles or packages and moves along the overhead rail. The hanger is suspended below the carrier holding in general the textile materials or packages. But the hanger can easily swing during operations, and so the materials or packages transported can collide each other, which ends down in process errors or product defects. Therefore the carrier motion must be made carefully. This research reports about the results that were obtained in trying to control the hanger swing as small as possible. In order to obtain the optimal carrier speed, the hanger of the overhead rail/trolley transfer system was represented by a model as a hanging pendulum. On the basis of the dynamics of the pendulum the optimal moving velocity of the carrier was simulated. Then, the theoretical results were compared with them for on/off operation. The research has shown that the optimal input can reduce the swing angle drastically compared to the conventional on/off operation.

虛擬出世:前往異次元的新世界

許維?(Xu, Wei-Ying) 동서미술문화학회 2015 미술문화연구 Vol.7 No.7

링 정방공정중의 사절수 추정

허유,이재곤,Heo, You,Lee, Jae-Kon 한국섬유공학회 1977 한국섬유공학회지 Vol.14 No.1

링정방 공정중의 사절수를 추정하기 위하여 간단한 수학적 모델를 만들었다. 사절현상에 가장 중요한 방사장력, 및 단사강력 만을 고려하여 사절수에 가장 기여도가 큰 요인을 찾아내고 사절율을 이론에 의해 유도하였다. A Study on the end breakages in ring spinning by simple mathematical model has been carried out. The most important factors such as yarn strength, yarn strength variation, spinning tension and spinning tension variation were considered among the factors known as affecting the breakage phenomena. The relative importance of such factors was investigated and the number of end breakages based on the mathematical model was calculated. From the theoretical results, it could be concluded that the value of end breakage rate is obtained and the most important factor contributed to breakages is yarn irregularity.

송출 및 권취 장력제어 시스템 개발에 관한 연구(II);장력거동의 수학적 모델링

허유,장승호,이석규,Huh, You,Jang, Seung-Ho,Lee, Suck-Gyu 한국섬유공학회 1998 한국섬유공학회지 Vol.35 No.9

In the weaving process the variations of the warp yarn tension cause irregularities of the weft density of the woven fabrics. Due to the fact that warp yarn tension varies in a great extent depending on the ratios of the take-up and the let-off speed, it is necessary to regulate the speed of let-off in relation to that of take-up operation for keeping warp yarn tension in a certain range allowable for the fabric quality. Therefore it is indispensable to analyze the dynamic characteristics of the take-up and let-off system for obtaining the weaving process optimally. In this research it was tried to get the dynamic characteristics of the let-off/take-up process theoretically, and the behavior of the warp yarn tension was simulated on the basis of the mathematical model, depending on the let-off and take-up speed, tensile properties and feeding tension of the warp yarns. From this research the following results could be obtained: 1) dynamic warp yarn tension can be described by a differential equation, however, nonlinearly with respect to the take-up speed, 2) the behavior of warp yarn tension has a characteristics of a 1st order system in the case of a constant take-up speed, and 3) variations of warp yarn tension can always occur when take-up speed changes.

이상고온 조건이 고추의 생육 및 수량에 미치는 영향

허유,강점순,김소희,박은지,손병구,최영환,이용재,박영훈,서정민,조재환,홍창오,이상규 경상대학교 농업생명과학연구원 2013 농업생명과학연구 Vol.47 No.2

본 연구는 우리나라의 대표적인 노지작물인 고추에서 이상고온에 따른 생육 및 생리장해 등 피해정도를 파악하기 위해 수행되었다. 아울러 고온피해를 최소화하기 위한 화학적 대응 기술을 확립하기 위해 빈나리(diniconazole)를 사용하여 그 효과를 검정하고자 하였다. 고추의 신장생장은 생육적온인 25℃보다 온도가 높아질수록 향상되었으나 경직경은 낮았으며, 특히, 30℃에서 재배한 고추 식물체는 연약한 생장을 보였다. 반면 뿌리생육은 생육온도에 따라 큰 차이는 없었다. 고추의 생육적온인 25℃보다 고온에서 재배하면 엽수는 증가하였고, 엽면적도 높았다. 또한 생체중 및 건물중도 높았다. 반면 수확량은 생육적온인 25℃에 비해 고온인 30℃에서는 생산량이 17% 감소하였다. 고추의 생육온도에 따라 낙화율에 차이가 있었으며, 생육적온인 25℃에서는 낙화율이 28.0%였으나, 27.5℃에서는 33.5%, 30℃에서는 52.3%로 온도가 높아질수록 낙화율이 높았다. 칼슘 결핍증은 고추의 생육적온에서는 나타나지 않았으나 온도가 높아질수록 경미하게 증가하는 경향이었다. 반면 역병발병율은 생육온도에 따른 차이는 없었다. 30℃의 이상고온은 낙화율이 문제되었으나, 빈나리를 처리하면 낙화율이 감소하여 10 mg/L 처리에서는 대조구에 비해 수량이 10% 향상되었다. Growth and physiological disorders caused by abnormally high temperatures were evaluated in an important field crop of pepper. In addition, chemical treatment for reducing the damages from high temperature was tested and its effect was verified using 'Binnari'(diniconazole). Shoot growth of pepper was improved as the temperature increased from 25℃, an optimum temperature for growth, while it's spasticity was low and plants cultivated at 30℃ showed relatively weak growth and development. However, root growth was not affected by the different temperatures. The number of leaf, leaf area, fresh weight, and dry weight were increased at the tempratures higher than 25C. Whereas, yield was decreased by 17% at 30℃ in comparison to 25C. Falling blossom rate was different depending on the growth temperature, and the rate of 28% at 25℃, 33.5% at 27.5℃, and 52.3% at 30℃ was observed, indicating that falling blossom rate increased as temperature rose. Calcium deficiency did not appeared at the optimum growth temperature, but slightly increased as the temperature goes up. Different growth temperatures did not affected on disease rate of phytopathora blight. Falling blossom was severe at abnormal temperatures higher than 30℃, but the treatment of 'Binnari' reduced falling blossom rate and increased the yield by 10% as compared to control. The optimum concentration for 'Binnari' treatment was 10mg/L

위사밀도 동역학 확장 모델과 시뮬레이션

허유,전두환,김종성,Huh You,Chun Du-Hwan,Kim Jong-S. 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.2

Modern weaving machines have the beat-up mechanism whose front position is predetermined mechanically. Therefore the relative position between the reed front and the clothfell plays an important role in producing the high quality fabrics with uniform weft density distribution. This research reports on the results from the simulation that was conducted on the basis of the theoretical model about the fabric weft density dynamics, including the factors such as beat-up motion and warp tension. Results showed that the weft density change was very sensitive to the initial clothfell position. The clothfell position was relocated toward the machine front during the machine restart and then it approached the steady state value. A low initial warp tension led to a narrow pickspace, too. Even though the warp tension and the beat-up force changed for a long period of time after the machine restarted, the weft interval variation and the clothfell position change were stabilized early, while the clothfell position showed an overshooting behavior for a low initial warp tension under a high level of process tension condition. Initial weft interval condition showed no influence on the dynamic behavior of the weft density.

링 방적사의 섬유 이주거동에 관한 연구(II) -이주거동에 의한 구조해석-

허유,김영률,류운영,Huh, You,Kim, Young-Ryul,Ryu, Woon-Young 한국섬유공학회 2004 한국섬유공학회지 Vol.41 No.4

Ring spun yam is the most widely used yarn type, especially for quality staple yarns. But the exact structure of the ring spun yarn is not known and the structure is explained only qualitatively. This study suggests a method for determining the structural characteristics quantitatively, defining a packing density (unction and a migration factor. The results show that ring spun yarn has a maximum packing density at around 2/3 of the yarn radius. The fibers in the yarn center are arranged parallel or with a small angle to the yarn axis, which is different from what has been known to us. The migration factor of a ring spun yarn ranges from 0.76 to 1.29. depending on the twist level that affects the fiber migration positively.

책임행정실현을 위한 구체적인 방안 - 공무원의 직무상의 책임한계책정이 필요하다

허유 대한지방행정공제회 1959 地方行政 Vol.8 No.70

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