• Journal of Institute of Control, Robotics and Systems
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• v.10 no.2
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• pp.153-163
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• 2004

The control objective in hard disk drives is to move head as fast as possible to target track and position the head over the center of target track in the presence of external disturbances. The external shock or disk clamping error in manufacturing process causes the disk center to deviate from the disk rotation center. The disk shift acts on the control system as disturbance and degrades severely the performance of disk drives. In this paper, we present a new controller that compensates for the periodic disturbances very fast. The disturbance compensator is arranged in parallel with the state feedback controller. To avoid the interference with the state feedback controller, the compensator creates compensation signal without the feedback of system output until steady state. The pulse type controller is included additionally for improving the transient performance due to initial state. Finally, in order to demonstrate the superior performance of the proposed compensator. we present some experimental results using a commercially available disk drive.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.325-331
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• 2006

This paper suggests the design methodology of a robust controller based on disturbance rejection controller using DSP. In this paper, we discuss process to put the disturbance rejection controller into practice, and examine the performance of disturbance rejection controller by implementing it on DSP based hardware to evaluate usefulness of controller. As a result, the proposed robust controller can not only stabilize system against disturbance ,but it improve controlling performance. And also, it shows convenient to put into practical use of industrial sites due to its easy implementation on the hardware.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.221-228
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• 2008

This paper presents a new method for world wide network motor controlled system. It uses disturbance observer to present high precision position control algorithm to disturbance change, and to apply this to induction motors. It shows that proposed algorithm is strong in induction motor precision control for disturbance change. This system with disturbance observer used deadbeat control, which have high benefit, is good for quick disturbance compensation. To show these effectiveness the whole process is simulated by simulink, and also experimented by DSP6416 with TCP-IP network board.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.329-329
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• 2000

In this paper, a spindle system using an electromagnetic exciter is proposed to compensate a spindle disturbance such as unbalance and machining force etc A spindle compliance can be readily varied with a disturbance which is generated by the interact ion between the spindle / workpiece structure and the cutting process dynamics. The varied compliance is one of the major constraints that deteriorates the surface quality of workpiece. This paper suggests a compliance compensation by using the EME in the proposed spindle system. To compensate the varied compliance, firstly a spindle system modeling was conducted by using the bond graph. Then the model is simulated by numerical analysis method and an optimal EME position is determined to compensate a disturbance effectively through simulation, which makes the bearing load to be minimized

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.230-233
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• 2005

This paper present a new method for world wide network motor controlled system. It use disturbance observer to present high precision position control algorithm to disturbance change, and to apply this to induction motors. It shows that proposed algorithm is strong in induction motor precision control for disturbance change. This system with disturbance observer used deadbeat control, which have high benefit, is good for quick disturbance compensation. To show these effectiveness the whole process is simulated by simulink, and also experimented by DSP6416 with TCP-IP network board.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.133-138
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• 1993

The stable and safe operation of a boiler system is essential for ensuring stability of the chemical processes. A dynamic simulation of a boiler drum was performed to identify the dynamics of the boiler drum. The obtained results represented that the variation of process variables disturb boiler system. So, disturbance rejection with tracking and constraints handing was necessary for stable operation of boiler drum. Among many controller, GPC has been known to show good performance in set point tracking than disturbance. In order to improve disturbance rejection performance measurable disturbance term was Introduced in basic GPC model. The controller which had tracking and disturbance rejection was designed for Improving the stable operation of a boiler system.

• Proceedings of the Safety Management and Science Conference
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• 2000.11a
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• pp.203-216
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• 2000

In this paper, we Investigate rationales for feedback adjustment using some techniques associated with automatic process control based on some nonstatioary disturbance models. Feedback-control schemes are often operated so that the nature of the disturbance that is being compensated is concealed and unusual deviations from the target cannot be taken account of. In this connection feedback control schemes is useful to extend the idea of common causes and special causes to such systems. Minimum-cost feedback schemes are discussed for some simple ,but practically interesting ,models.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.453-457
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• 2004

EPC seeks to minimize variability by transferring the output variable to a related process input(controllable) variable. In the case of product control, a very reasonable objective is to try to minimize the variance of the output deviations from the target or set point. We consider an alternative EPC model with first-order autoregressive disturbance.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.3
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• pp.83-97
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• 2009

The objects of study is to propose criteria for physical river disturbance assessment and as case study to show the application results for river improvement. For this purpose, the river disturbance assessment method for past disturbance process and the present-day potential natural state of stream is proposed. To assess the disturbance of the Youngcheon River caused by river improvement, One ares of Nam River was selected for the reference reach and two areas of Youngcheon River were selected for the comparison reach. And these reaches were surveyed and analyzed according to applying criteria of the river disturbances assessment. The assessment indices were physical factors as like epifaunal (bottom), embededness, velocity/depth regime, sediment deposition, channel flow status, channel alteration, frequency of riffles, bank stability, vegetative protection and riparian zone etc. The results showed that physical river environment in Youngcheon River area was disturbed by artificial revetment and bed excavation, consequently this disturbance give rise to impact of ecosystem in river. Hereafter, the criteria for river disturbance assessment are needed to consider various river characters as bed materials and bed slop etc.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.153-167
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• 2022

This study proposes a method to analyze the distribution of coal porosity disturbances after the excavation of ultra-large-diameter water jet boreholes using a coal wetting and softening model. The high-pressure jet is regarded as a short-term high-pressure water injection process. The water injection range is the coal softening range. The time when the reference point of the borehole wall is shocked by the high-pressure water column is equivalent to the time of high-pressure water injection of the coal wall. The influence of roadway excavation with support and borehole diameter on the ultra-large-diameter jet drilling excavation is also studied. The coal core around the borehole is used to measure the gas permeability for determining the porosity disturbance distribution of the coal in the sampling plane to verify the correctness of the simulation results. Results show that the excavation borehole is beneficial to the expansion of the roadway excavation disturbance, and the expansion distance of the roadway excavation disturbance has a quadratic relationship with the borehole diameter. Wetting and softening of the coal around the borehole wall will promote the uniform distribution of the overall porosity disturbance and reduce the amplitude of disturbance fluctuations.