• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.605-608
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• 1997

In this paper, the case study of reducing rotational errors is done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and ed nonlinear dynamics of electromagnets. For the most case, the electrical runout of sensor target is big even in well-finished surface; this runout can cause a rotation error amplified by feedback control system. The adaptive feedforward method based on LMS algorithm is discussed to compensate this kind of runout effects, and investigated its effectiveness by numerical simulation and experimental analysis. The rotor orbit size in both bearings is reduced about to 5 pin due to lX rejection by feedforward control up to 50,000 rpm.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.119-124
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• 2001

As the brake control valve of freight car, there are sliding valve and diaphragm one. In this study, we measured and analyzed pneumatic characteristics of brake system of the freight car by using real train experiment. The difference of the release time appears in the freight car incorporated with sliding and diaphragm valve respectively. We adapted quick release valve to reduce the difference of the release time and also found that this valve is useful for the purpose.