• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.107-114
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• 2000

Rollers and rolls in the continuous process systems are noes of key components that determine the quality of web products. The condition of rollers and rolls(ex. eccentricity wear) should be consistently monitored in order to maintain the process conditions (ex. tension, edge position) within a required specification. In this paper, a new diagnosis technique is suggested to detect the defect of rollers/rolls (ex. eccentricity, wear) based on frequency domain analysis of web tension signal. The kernel of this technique is to use the spectrum amplitude of tension signal which allows to identify the fault rollers/rolls and to also diagnose the degree of fault in corresponding rollers and rolls. The experimental results proved that the suggested diagnosis technique can be successfully used to identify the defect rollers and rolls as well as to diagnose the degree of the defect of those rollers. The suggested technique can be applied to monitor and diagnose the shape of rollers and rolls in various multi-span web transport systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2029-2037
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• 1997

In a web winding process, the contact roll plays many important roles including air-entrainment control and WIT(Wound In Tension) regulation. The behavior of contact roll significantly affects the winding tension characteristics specifically at the time of contact when the speeds of contact roll and the winding roll are not synchronized. A mathematical model for the web, the winding roll, and the contact roll is derived. By using the model derived, a nonlinear PID(NPID) controller is designed to control the winding tension at the time of contact and separation between the contact roll and the winding roll. Computer simulation study showed that the performance of the winding system with the NPID controller significantly improved compared with that of a system with PID controller.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.65-72
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• 2000

This paper presents the study of the tension control in a web transfer system. In this study the sliding mode controller is applied to a time-varying nonlinear mathematical model. The model was derived to consider the effects of changing the roll radius in tension variation during winding and unwinding. The uncertainty in modeling may be due to unmodelled dynamics, on variations in system model. Designed sliding mode controller made the system error always staying in the suggested surface from the beginning. Through this, system is maintained to be robust against a disturbance and uncertainty. To verify the designed controller has a good performance, various inputs such as desired velocity, step input, and trapezoidal input are applied. When the sliding mode controller was used, the system(the tension control) performance was improved comparing to the PID controller. The robustness of the controller with respect to an estimation error was verified through simulations.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.165-170
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• 2001

In the continuos process systems, traction between a moving web and rollers is one of key mechanisms for the study of major issues including the distributed control of tension, guiding, wrinkling, winding, and scratching. Energy is transferred from the driven rollers to the web and from the web to the idle rollers through traction. The characteristics of friction play major role in the determination of the traction force between the moving web and the rollers. In this paper the characteristics of friction between the moving web and the rollers are studied. A procedure to determine the friction coefficient between the moving web and rollers is developed. An experimental setup to validate the procedure is devised. Experimental results showed that the value of traction coefficient decreases as the operating web speed increases and increases as the operation web tension increase.

• Journal of Mechanical Science and Technology
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• v.19 no.4
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• pp.958-967
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• 2005

The mathematical model for tension behaviors of a moving web by Shin (2000) is extended to the tension model considering the thermal strain due to temperature variation in furnace. The extended model includes the terms that take into account the effect of the change of the Young's Modulus, the thermal coefficient, and the thermal strain on the variation of strip tension. Computer simulation study proved that the extended tension model could be used to analyze tension behaviors even when the strip goes through temperature variation. By using the extended tension model, a new tension control method is suggested in this paper. The key factors of suggested tension control method include that the thermal strain of strip could be compensated by using the velocity adjustment of the helper-rollers. The computer simulation was carried out to confirm the performance of the suggested tension control method. Simulation results show that the suggested tension control logic not only overcomes the problem of the traditional tension control logic, but also improves the performance of tension control in a furnace of the CAL (Continuous Annealing Line).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.333-334
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• 2006

A novel mathematical modeling in web transport systems for Continuous Annealing Processes (CAP) is proposed. Despite of thermal and weight effects in dynamics of web transport systems, the conventional mathematical model does not consider those effects. Disregard of these effects causes the low manufacturing quality of webs in CAP. In order to improve the manufacturing quality of webs in CAP, moreover, precise tension control is required based on the mathematical model. Therefore, an advanced mathematical model considering thermal and weight effects in CAP should be established. The effectiveness of a novel mathematical model is evaluated by comparing the performances of the PI tension control system based on the proposed mathematical model with that based on the conventional one through the computer simulation.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.873-878
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• 2007

Stability of high-speed roll-to-roll printing machines is one of the most important factors that are required for the printing machines to operate properly and to obtain reasonable printing performance. This paper proposes a new model for the web-tension system of a high-speed gravure printing machine considering span-length variations due to dancer rollers, and analyzes the stability of plant dynamics of the printing machine using the proposed model. Span-length variations due to dancer motions are considered for the modeling of plant dynamics in two ways; one is to include the effect of span-length variations without considering dancer inertias and viscous frictions, and the other is to include the effect of span-length variations with considering dancer inertias and viscous frictions. The stability of the plant model is analyzed for various web-speeds using the eigenvalues of the linearized model about operating points.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.281-284
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• 2006

ASCE-ACI Committee 426 and 445, on Shear and Torsion, well noted in their report that recent research work regarding shear and torsion had been devoted primarily to members. But it was not logical approach of PSC members applied by axial force based on the shear deformation in web element. And it was not included that the effect of axial is to shift the shear strain(or crack width) in the web element versus the applied shear curve up or down by the amount by which the biaxial tension-compression state varies. The shear strength also increases or decreases, so that the change in shear strain at service load due to the presence of axial load is to some extent changed. Generally, in corresponding beams the shear strain at service load is less in the beam subject to axial compression and greater in the beam subject to axial tension, than in the beam without axial load. In particular, however, no research were available on the shear deformation in shear of PSC members with web reinforcement, subject to axial force in addition to shear and bending. Therefore, this study was basically performed to develop the program for the calculation of the shear deformation based on the shear effect of axial force in prestressed concrete members.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.45-52
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• 1998

The contact roll is often used to regulate the winding tension as well as the entrained air in a wound roll by adjusting the contact force to the winding roll. But the contact force generated by other rolls, like assistant nip rolls, in a winding(or roll changing) process may act as disturbance to the control of the winding tension. In this paper, the mechanism of a roll change process is analysed. Ana, the behavior of the contact and the nip rolls are mathematically modeled. A nonlinear PID(NPID) controller is designed to control the winding tension and to reject the effect of disturbance generated by the nip roll on the winding tension variation. Computer simulation study showed that the performance of the suggested NPID controller is improved compared with that of the PID controller in controlling the winding tension and in rejecting the effect of the disturbance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.748-753
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• 1996

The contact roll is often used to regulate the winding tension as well as the entrained air in a wound roli by adjusting the contact force to the winding roll. But the contact force generated by other rolls, like assistant nip rolls, in a winding(or roll changing) process may act as disturbance to the control of the winding tension. In this paper, the mechanism of a roll change process is analyzed. And, the behavior of the contact and the assistant nip rolls are mathematically modeled. A nonlinear PID(NPID) controller is designed to control the winding tension and to reject the effect of disturbance generated by the assistant nip roll on the winding tension variation. Computer simulation study showed that the performance of the suggested NPID controller is improved compared with that of the PID controller in con trolling the winding tension and in rejecting the effect of the disturbance.