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연조 슬라이버의 선밀도 거동 해석. II. 연조비와 롤러 간격 효과
임정호,김종성,허유,Lim, Jung Ho,Kim, Jong S.,Huh, You 한국섬유공학회 2018 한국섬유공학회지 Vol.55 No.6
The behavioral characteristics of sliver linear density under roller drafting operation were investigated in this study. A theoretical model describing the dynamic behavior of the staples flowing in a single direction was applied. While the model parameters remained constant, the process parameters including draw ratio and roller distance were varied. Simulations of the dynamic behavior of the drawn sliver linear density showed that it was dependent on the process conditions, and the effects varied depending on the staple length distribution. For uniform length staples, the linear density of the drawn sliver showed periodic changes at a steady state when the drawing roller distance was long. For the short drawing zone, the drawn sliver exhibited a constant steady state linear density. Increasing the draw ratio caused the linear density to change periodically which resulted in an increase in the CV% of the drawn sliver linear density. For length distributed staples, the linear density was sensitive to the draw ratio. At a low draw ratio, for example, DR=4, the drawing zone length did not affect the sliver linear density, and a constant linear density was observed. However, at high draw ratios, for example, DR=12, the drawing zone length affected the linear density behavior of the drawn sliver, showing periodic changes in the steady state. Thus, high draw ratios and long drawing zones caused a drastic increase in the CV% of the quasi-steady state linear density. In general, the two passes of sliver in a drawing operation with low draw ratio resulted in improved properties, that is, a more even linear density of the drawn sliver than that obtained using single drawing pass with a high level draw ratio, which drastically increased the linear density.
임정호,김종성,허유,Lim, Jung Ho,Kim, Jong Sung,Huh, You 한국섬유공학회 2016 한국섬유공학회지 Vol.53 No.4
During friction yarn formation, fiber fleece is fed continuously into the gap between two surfaces moving at different speeds to build a bundle. This bundle is then pulled out of the gap and taken up onto a bobbin. During this process, the bundle obtains twists that are generated in two forms-one by fiber arrangement and the other by torque. Twists are generated in two zones, which are the friction zone and the take-up zone. Therefore, the total twists can be obtained by adding all twists occurring in the two zones. The presented research reports the structural characteristics of the friction yarn based on theoretical twist models. The yarn structure represented by the arrangement of the constituent fibers is analyzed by simulation of the theoretical models. Results show that the fiber arrangement twists are directionally opposite to the torque twists in the friction zone; for example, fiber arrangement twists are S-twists and torque twists are Z-twists. In the take-up zone, the twist generation occurs in the Z-direction. Thus, the total twist per length of the friction-spun yarn is uniformly distributed along the bundle radius. More specifically, the resultant overall twist is zero, theoretically.
제트 환기 시스템 도입에 의한 플랜트 기자재 용접장의 환경 개선 효과 분석
임정호,이태구,문승재,이재헌,Lim, Jung-Ho,Lee, Tae-Gu,Moon, Seung-Jae,Lee, Jae-Heon 한국플랜트학회 2008 플랜트 저널 Vol.4 No.2
In this inquiry, I would suggest jet ventilation system for effective elimination of welding flaw at machinery material welding shop on plant and evaluate the airstream on inner space and property of welding flaw's density through the examination. We can know outer atmosphere inflows at the speed of about 0.05m/s from western entrance in case of stopping the jet ventilation system, but airstream is accumulated on entire space. At height of worker's breathing surface(Ground Level = 1.5 m, below of GL) and welding work center, density of welding flaw on upper part(GL = 12m) is appeared 4 times higher than outer atmosphere at surplus range besides nearby of western entrance. At operation of jet ventilation system, since the smooth air current transfer at inner space and exhaust effect the wind speed is maintained at 0.932 m/s at the point of height of worker's breathing surface on inner space and it's concluded about the working conditions have been better than before operation of jet ventilation system because of that results show that inner space density of welding flaw at height of worker's breathing surface is 40.5%, and in the work shop, it is 20.3% at upper part.
임정호,방선배,박광묵 한국화재조사학회 2018 한국화재조사학회 학술대회 Vol.2018 No.04
본 논문에서는 동파방지용으로 쓰이는 직렬형 열선과 자기온도제어기능이 있는 정 온전선의 원리 및 구조를 살펴보고 정상동작 실험과 단락실험을 통해 전류의 파형, 크 기 등의 전기적 특성 및 피복의 온도변화를 비교분석하였다. 직렬형 열선의 경우 단락 전류는 정상동작 상태의 전류보다 약 3배 높았지만 상승한 온도는 피복의 허용온도보 다 낮게 측정되었다. 정온전선의 단락전류는 82.5A로 측정되었으며 컨트롤러 PCB패턴 이 용단되면서 아크가 발생하는 화재요인이 도출되었다. 단락실험 결과 정온전선은 직 렬형 열선에 비해 화재위험성이 더 높음을 확인하였다. 그러나 열선을 감싸고 있는 피 복의 재질은 정온전선이 직렬형 열선에 비해 강도가 높아 피복 소손에 의한 단락 발생 위험이 낮음을 확인하였다.