• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.359.1-359
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• 2002

Servo performance of a disk drive is greatly affected by the mechanical resonance frequencies of the head gimbal assembly(HGA). It is important (actor to allow broader bandwidth for servo system in improving overall drive performance. In this paper, an optimal design for ODD suspension is attempted to increase resonance frequencies. It was decided that the first resonant frequency in tracking direction was higher than 5㎑. (omitted)

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.380-383
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• 2003

This paper proposes a new and simple input prediction method for robust servo system. This servo system uses robust tracking control system based on both Coprime Factorization(CF) and Zero Phase Error Tracking control system. The CF control system can be designed simply and systematically. Moreover, this system has not only stability but also robustness and disturbance rejection ability The optical disk tracking servo system can detect only the tracking error. So the new and simple input prediction system proposed in this paper estimates the reference input signal from the tracking error. Numerical simulation results show that the proposed method is effective.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.66-68
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• 2009

Most hard disk spindles currently used are supported by oil lubricated hydrodynamic bearings. However, in the trend of increasing spindle speed and reducing size and cost, dynamic behaviors of the bearing such as RRO and NRRO are more important. A novel system evaluating dynamic behavior of hydrodynamic bearings in had disk drive was developed to analyze the effect of groove shapes and parameters.

• Journal of Engineering Education Research
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• v.19 no.6
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• pp.44-48
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• 2016

This research is one of the Industry-University cooperation in idea factory of Korea Maritime and Ocean University. Idea factory of Korea Maritime and Ocean University is trying to train creative talented students and discover ingenious ideas. The contents are consisted of the possibility for the replacement of a metal valve disk to composite valve disk in butterfly valve based on the diversification. Purpose in this study is to predict failure field by each fly by appling Tsai-Wu Failure Index.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.1
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• pp.1-10
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• 2005

This paper proposes a new and simple input prediction method for robust servo system. A robust tracking control system for optical disk drives was proposed recently based on both Coprime Factorization (CF) and Zero Phase Error Tracking (ZPET) control. The CF control system can be designed simply and systematically. Moreover, this system has not only stability but also robustness to parameter uncertainties and disturbance rejection capability. Since optical disk tracking servo system can detect only tracking error, it was proposed that the reference input signal for ZPET could be estimated from tracking errors. In this paper, we propose a new control structure for the ZPET controller. It requires less memory than the previously proposed method for the reference signal generation. Numerical simulation results show that the proposed method is effective.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1069-1076
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• 2002

Contamination particles in a hard disk drive can cause serious problems including slider crash and thermal asperities. A recirculation filter is typically installed in the hard disk drive to remove the particles. Measurements and theoretical predictions of particle concentration decay with the filter are carried out for a commercially available HDD. Especially, the effect of disk rotational speed on the particle capture efficiency is investigated. Results show that filter efficiency is higher for higher disk rotational speed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.674-677
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• 2002

In this paper, two kinds of windmill type motors which have a disk shape and a ring shape piezoelectric ceramics were studied. And characteristics of two models were compared with each others. A windmill type ultrasonic motor is composed of a stator, a rotor, and a ball bearing. The stator is made of a piezoelectric ceramics and two metals endcaps. When the piezoelectric ceramics vibrate, displacement of torsonal vibration appear at metal endcaps. The motor with 11.0[mm] diameter was studied by finite element analysis. The voltage of 100[V] was supplied at each model. Resonance frequency of 206.875[KHz] was obtained at the disk type, but ring type was 137.562[KHz]. The maximum torsonal displacement of $1.112[{\mu}m]$ was obtained at the disk type, but ring type was $1.698[{\mu}m]$.

• Journal of Power System Engineering
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• v.13 no.1
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• pp.33-38
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• 2009

In this study, the nose of cam in the automobile engine was modelled into circular disk to analyze the torsional vibration of the cam shaft. The distance between disks was fixed, but the diameter of disks was changed. The torsional vibration of the cam shaft was studied experimentally by the motion of the modelled disk with changing the disk diameter. And the sizes of the modelled disk were selected not to show the natural frequencies over all the experimental ranges. The torsional vibration meter used in this study has a laser system with non-contact measurement method, which can measure both torsional angular vibration velocity and torsional angular vibration displacement simultaneously. The Experimental analysis shows that the characteristics of the torsional vibration in the horizontal rotating shaft can be considerably affected by the arrangement of the modelled disks.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1517-1518
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• 2008

Optical disk driver is being used in many electronic products besides computer. In particular, the demands are recently increased as an optical disk player in the mobile products such as camcorder or in the home theater appliances, or etc. However, under these circumstances, the disturbance inputs to the optical disk player increase gradually. In this paper, for reducing the possibility of malfunction of the optical disk player, we propose the method of detecting and controling the non-periodic external shock of the disturbances. Also, we execute some simulations and actual experiments and discuss the results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.744-752
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• 1999

Particle contamination in a hard disk drive has been recognized as an important issue because particles can significantly affect the reliability of the drive. In this study, characteristics of the particle generation in a hard disk drive during the start/stop period were investigated. The number of particles generated in the drive was measured at 5 locations by using condensation nucleus counters(CNC) with sampling probes. It was found that most of particles were generated whenever the drive started or stopped. The number of particles detected by the condensation nucleus counter depended on sampling parameters including sampling location, shape of sampling probe, and sampling velocity.