• International Journal of Automotive Technology
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• v.8 no.4
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• pp.445-453
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• 2007

This paper presents a robust controller design approach for improving vehicle dynamic roll motion performance and guaranteeing the closed-loop system stability in spite of vehicle parameter variations resulting from aging elements, loading patterns, and driving conditions, etc. The designed controller is linear parameter-varying (LPV) in terms of the time-varying parameters; its control objective is to minimise the $H_{\infty}$ performance from the steering input to the roll angle while satisfying the closed-loop pole placement constraint such that the optimal dynamic roll motion performance is achieved and robust stability is guaranteed. The sufficient conditions for designing such a controller are given as a finite number of linear matrix inequalities (LMIs). Numerical simulation using the three-degree-of-freedom (3-DOF) yaw-roll vehicle model is presented. It shows that the designed controller can effectively improve the vehicle dynamic roll angle response during J-turn or fishhook maneuver when the vehicle's forward velocity and the roll stiffness are varied significantly.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.76-80
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• 2007

Two roll straightener showed the remarkable improvement in straightness betterment of the bar compared with other types of straightener. So, in this study we designed a two-cross straightener curvature for the straightness improvement of a bar and contact sections with respect to the variation of the gap between two-cross roll using nonlinear contact analysis. The Displacement in terms of a intersection angle between roll and bar was predicted on with the effect of a straightness and plastic deformation behaviors of the bar according to the roll drive of a two cross-roll straightener.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.492-500
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• 2002

This paper presents a study of the effect of varying the roll gap of oval pass in round-oval-round pass sequence on the interracial slip of workpiece, entrance and exit velocities, stresses and roll load that the workpiece experiences during rolling, by applying analytical method, finite element simulation and verification through hot bar rolling tests. The results have shown that the roll gap variation of oval pass affects the interfacial slip of workpiece along the groove contact and the specific roll pressure. The optimum conditions in terms of minimum interfacial slip and minimum specific roll pressure, which might influence the maximum groove life, is obtained when the subsequent round pass is completely filled.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.128-134
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• 1993

Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions and lubrication. The tests were performed to find the effects of rolling materials under the same lubrication conditions. The obtained results are as follfws; 1) The decrease in surface roughness of work roll is more rapid in that case of continuously cast A1-killed steel strip than ingot cast steel strip. In rolling of continuously cast A1-killed steel strip, worn powder rich in A1$\_$2/O$\_$3/sticks to the work roll surface, and so it makes the mirror surface of work roll accelerate. 2) Amount of work roll wear is small in rolling of continuously cast A1-killed strip. 3) In rolling of continously cast A1-killed steel strip, it is necessary to put up the intial surface roughness of work roll in order to prevent work roll slip.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.451-458
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• 2003

A ship with small metacentric height or high speed vessel performs relatively large roll angles in her manoeuvring motion. Roll coupling effect should be taken into consideration for accurate prediction of manoeuvring motion of such a ship. This paper proposes a new mathematical model of ship manoeuvring motion taking coupling effect of roll into consideration. Some kinds of manoeuvring motion are simulated by computer, based upon the proposed model. The simualted results by proposed model here are compared with those by existing model. The proposed model is found to be practical and useful for prediction of manoeuvring motion with roll effect.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.4
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• pp.247-253
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• 2005

This study investigated the effects on foot and ankle roll-over characteristics according to different heel heights during walking. Fifteen female volunteers who have neither musculoskeletal nor foot problems were participated in gait analyses, wearing four different pairs of shoes in different heel heights. To obtain roll-over shape of foot/ankle complex, we used trajectories of knee and ankle joints as well as the renter of pressure between initial contact and opposite initial contact. Results revealed that the entire roll-over shape moved distally as the heel height increased but roll-over characteristics showed uniformly with different heel heights. In addition, we found that nondisablea persons automatically adapted to their foot/ankle complex to varying heel heights within 6cm, by moving the origin of roll-over shape distally to maintain roll-over characteristics. However, since the balance of the gait only by the ankle joint could not be achieved beyond the heel height of 6cm, compensations at the knee and the hip joints occurred simultaneously. Roll-over characteristics in human walking would provide simpler and wider understanding of human walking, and furthermore could be applied to the wide understanding of prosthetics and orthotics of the lower extremity as well as orthopaedic shoes.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.4
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• pp.339-346
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• 2016

The aim of this research was to the experimental data using statistical and spectral analyzing method to get the motion reponses of a stern trawler in operation states such as drifting, sailing and trawling according to the wave height. In drifting, the significant and the maximum valuer of roll in beam sea increased according to the wave height, but those of pitch decreased. The response and the period of peak of roll in beam sea were increased, but those of pitch decreased. In navigation, the significant and maximum values of roll increased remarkably according to the wave height, but those of pitch changed a little. The response of roll was highest in quartering sea, beam sea and then following sea, but those of pitch was highest in bow sea, head sea and then beam sea in the order of all wave heights. The period of peak of roll due to the wave height and the wave direction changed from 3.8 to 9.9 seconds, and those of pitch changed from 3.3 to 10.4 seconds. In trawling, the significant and maximum values of roll increased a little according to the wave height, but those of pitch increased significantly. The response of roll was highest in beam sea, bow sea and then quartering sea, but those of pitch was highest in head sea, following sea, and then beam sea in the order. The period of peak of roll due to the wave height and the direction changed from 6.6 to 10.9 seconds, and those of pitch changed from 6.7 to 11.2 seconds.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.4
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• pp.25-29
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• 2015

Demand for a low-cost, high-throughput, and high-resolution patterning method for fabricating devices continues to increase. The roll-to-roll (R2R) imprint lithography technique has received a great deal of attention as a means of fabricating next-generation devices. In this paper, we propose a fabrication method for polymeric planar lightwave circuit (PLC) devices that uses R2R imprint lithography. The proposed technique uses an elastomeric polydimethylsiloxane (PDMS) mold. A Si wafer with micro patterns is used as the Si master. The PDMS mold is then replicated from the Si master. By applying a precise web tension and at a given web speed, we fabricated a micro-patterned PLC device. The insertion losses were 4.0 dB for a $1{\times}2$ optical splitter. As such, the proposed method of fabricating a PLC device by the R2R process was shown to be an effective solution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.64-64
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• 2008

연속공정이 가능한 Roll to Roll sputter system을 이용하여 플렉시블 indium tin oxide(ITO) 투명전극을 PET(polyethlyene terephthalate) 기판위에 성막하였다. 연속 성막공정을 위해 Roll to Roll sputter system에서의 unwinder roller와 rewinder roller를 이용한 servomotor의 rolling으로 기판의 움직임이 완벽히 제어되었으며, 외부 응력으로 부터의 안정성 및 성막 공정 시의 PET 기판의 열적 변형을 최소화하기 위한 접촉식 냉각방식의 cooling system을 main drum으로 사용하였다. 또한 고분자 기판과 투명전극 사이의 adhesion을 향상시키기 위한 전처리 공정으로 gridless linear ion beam source를 pretreatment system으로 구축하였다. 이렇게 제작된 Roll to Roll sputter system을 이용하여 PET 기판위에 연속공정을 통해 ITO 투명전극을 성막하였다. 성막된 플렉시블 ITO/PET 투명전극은 XRD, HREM, SEM 분석을 통하여 main drum의 cooling에 의해 완전한 비정질 구조를 나타내었음을 확인할 수 있었으며, 비록 Roll to Roll sputter system을 통하여 상온에서 성막 되었음에도 불구하고 최적화 된 조건에서 가시광선 영역 83.46 %의 높은 광투과도 값과 47.4 Ohm/square의 비교적 낮은 먼저항 값을 얻을 수 있었다. 또한 Bending test 결과를 통하여 ion source의 전처리 공정으로 굽힘/평의 반복적 응력에 따른 전기적 특성 열화를 최소화 할 수 있음을 보였다. 최적화된 플렉시블 투명전극을 이용하여 P3HT:PCBM 기반의 플렉시블 유기태양전지를 제작하였으며, 제작된 유기태양전지로부터 1.88%의 power conversion efficiency (PCE)을 확보함으로써 플렉시블 유기태양전지 제작을 위한 ITO/PET 투명전극 성막 공법으로써 Roll to Roll sputter system의 적용가능성을 확인할 수 있었다.

• Laser Solutions
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• v.16 no.4
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• pp.12-16
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• 2013

For mass production of electronic devices, the processing of the printing roll is one of the most important key technologies for printed electronics technology. A roll of printing process, the gravure printing that is used to print the electronic device is most often used. The indirect laser processing has been used in order to produce printing roll for gravure printing. It consists of the following processing that is coating of photo polymer or black lacquer on the surface of printing roll, pattering using a laser beam and etching process. In this study, we have carried out study on the coating and etching for $25{\mu}m$ line width on the printing roll. To do this goals, a $4{\mu}m$ coating thickness and 20% average coating thickness of the coating homogeneity of variance is performed. The factors to determine the thickness and homogeneity are a viscosity of coating solution, the liquid injection, the number of injection, feed rate, rotational speed, and the like. After the laser patterning, a line width of $25{\mu}m$ or less was confirmed to be processed through etching and the chromium plating process.