• Structural Engineering and Mechanics
• /
• v.65 no.1
• /
• pp.91-98
• /
• 2018

Three structure-dependent integration methods with no numerical dissipation have been successfully developed for time integration. Although these three integration methods generally have the same numerical properties, such as unconditional stability, second-order accuracy, explicit formulation, no overshoot and no numerical damping, there still exist some different numerical properties. It is found that TLM can only have unconditional stability for linear elastic and stiffness softening systems for zero viscous damping while for nonzero viscous damping it only has unconditional stability for linear elastic systems. Whereas, both CEM and CRM can have unconditional stability for linear elastic and stiffness softening systems for both zero and nonzero viscous damping. However, the most significantly different property among the three integration methods is a weak instability. In fact, both CRM and TLM have a weak instability, which will lead to an adverse overshoot or even a numerical instability in the high frequency responses to nonzero initial conditions. Whereas, CEM possesses no such an adverse weak instability. As a result, the performance of CEM is much better than for CRM and TLM. Notice that a weak instability property of CRM and TLM might severely limit its practical applications.

• Transactions on Control, Automation and Systems Engineering
• /
• v.2 no.4
• /
• pp.262-267
• /
• 2000

In this paper, the magnitude of undershoot and overshoot in a prototype second order system with one positive real zero is computed by the analytic methods. Also, it will be shown that the peak times of the undershoot and overshoot can be calculated using the impulse and step response of the second order system. Three different cases are investigated: underdamped(p<ζ<1), critically damped(ζ=1) and overdamped(ζ>1) cases. We deal with the undamped(ζ=0) case as a special case of the underdamped. And a compensation method is proposed to reduce undershoots of the nonmininmun phase system using feedforward compensator.

• Journal of Power Electronics
• /
• v.18 no.3
• /
• pp.902-909
• /
• 2018

This study investigates the influences of different core parameters on the dynamic performances, such as rise time and overshoot, in pulse transformers for the triggering circuit of SCRs. First, a simplified transformer equivalent circuit, which emerges from a standard transformer equivalent circuit, is developed to analyze the step response. Second, the relations between the dynamic performances and the parasitic parameters are calculated by the simplified equivalent circuit. Third, the variations of rise time and overshoot, which are vital to the stability of triggering SCRs, with different core parameters, such as mechanic dimensions and topologies, are comprehensively investigated by analyzing the parasitic parameters. Finally, prototype transformers are fabricated to experimentally validate the analysis. The presented method can practically instruct the design of a pulse transformer for triggering SCRs.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 1998.03a
• /
• pp.43-46
• /
• 1998

This paper presents a new parameter tuning method for PID controller. The Ziegler-Nichols Parameter tuning has been widely known as a fairly heuristic method to good determine setting of PID controllers, for a wide range of common industrial processes It has a excessive overshoot in the set point response, set point weighting can reduced the overshoot to specified values. It will also be shown that set point weighting is superior to the conventional solution of reducing large overshoot by other method. In this paper, we will modified the Ziegler-Nichols tuning formula by fuzzy set. These method will give appreciable improvement in the performance of PID controllers.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.41 no.6
• /
• pp.11-16
• /
• 2004

The integral term of PID controller have the advantage of reduced steady state error and the disadvantage of accumulated errors. We proposed a method that maintains its advantage and improvs the disadvantage in transient response. The proposed PID control method with modified integral parameter accumulates errors in increment section and ignores errors in decrement section. Therefore, the proposed PID control method decreases overshoot, and makes settling time faster than conventional PID control method.

• Journal of IKEEE
• /
• v.20 no.1
• /
• pp.119-122
• /
• 2016

In this paper, we propose LDO regulator to operate using Pseude resistor instead of widely used Feedback resistor in conventional LDO regulator. Proposed Feedback network using Pseudo resistor has smaller area than the conventional feedback resistor and plays the role of an conventional LDO regulator. Thus, it has been proposed to compensate for the disadvantages of LDO regulator with noise. Although proposed LDO regulator compared with conventional LDO regulator has similar performance, this LDO regulator provide higher efficiency by reducing the overshoot and decreasing the area. This circuit was designed to using a Dongbu Hitek 0.18um CMOS process.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.10
• /
• pp.591-598
• /
• 2017

Power overshoot phenomenon was observed in microbial fuel cells (MFCs) used non-catalyzed graphite felt as cathode. Voltage loss in MFCs was mainly caused by cathode potential loss. Cheap stainless steel scrubber, which has high conductivity, and Pt/C coated graphite felt as cathode were used for overcoming power overshoot and reducing the cathode potential loss in MFCs. The MFCs used stainless steel scrubber showed no power overshoot even slow catholyte flow rate and produced 29% enhanced maximum current density ($23.9A/m^3$) than MFCs used non-catalyzed graphite felt while the power overshoot phenomenon was existed in Pt/C coated MFCs. Increasing catholyte flow rate resulted in disappearing power overshoot of MFCs used non-catalyzed graphite felt. In addition, maximum power density and current density of both MFCs used non-catalyzed graphite felt and stainless steel scrubber increased by 2-3.5 times. Cathode potential losses in all region of activation loss, ohmic loss, and mass transport loss were reduced according to increase of catholyte flow rate. Therefore, stainless steel scrubber has advantages that are economical materials as electrode and prevents power overshoot, leading to enhance electricity generation. In addition, increasing catholyte flux is one of great solution when power overshoot caused by cathodic overpotential is observed in MFCs.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.04a
• /
• pp.346-351
• /
• 2002

Several algorithm applied to single axis feed system with linear motor has been extensively reviewed in order to check the possible applicability to two axis system Among several factors considered, overshoot of the response was the most important one in minimizing position tracking error. Balance between overshoot and settling time has be adjusted to guarantee to best tracking performance.

• Tribology and Lubricants
• /
• v.20 no.1
• /
• pp.14-20
• /
• 2004

In high-speed gas-levitation applications a high compressibility number may bring a numerical difficulty in predicting generated pressure profiles accurately as it causes erroneous sudden pressure overshoot and oscillation in the trailing-edge. To treat the problem, in this study an exact exponential high-order shape function is introduced in the FE lubrication analyses. It is shown by various example applications that the high-order shape function scheme can successfully subdue undesired pressure overshoot and oscillation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.10a
• /
• pp.405-410
• /
• 2002

Linear motor food system control algorithm was extended to the two axis system. Among several factors considered, overshoot of the response was the most important one in minimizing position tracking error. Balance between overshoot and settling time has to be adjusted to guarantee to best tracking performance. Tracking route was carefully executed to eliminate the possible error during the machining process. Even though there exists slight discrepancy between desired mute and cutting track at the corner, precision machining could be implemented using the cutting scheme introduced.