• Transactions of the Society of Information Storage Systems
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• v.2 no.2
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• pp.123-129
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• 2006

The head to disk spacing must be decreased to increase recording densities in hard disk drives. Recently, to decrease the head to disk spacing, smooth disk having no bumps onto the lading zone has used. In this research, we compared the number of particles generated ill HDD with smooth and textured disks. We used a sampling method using a particle sampler and a CPC (condensation particle counter) to detect particles in HDD. First, we sampled and counted particles generated with disk rotational speed and various rest times when the smooth disk and textured disks were used, then analyzed the sampled particles by SEM (scanning electron microscopy) and AES (auger electron spectroscopy). In results of measuring particles, more particles in case of LZT disk drive generated than that of the smooth disk drive in all test modes. The number of particles generated in the smooth disk was very low. The particle generation increased as the rest time increased (smooth/LZT disks) and more particles in case of LZT disk drive generated than that of the smooth disk drive. In results of analyzing particle components, Al, Ti, Si components were detected and we could not found differences between components in case of smooth/LZT disk drive.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1056-1061
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• 2000

Particles existing in a hard disk drive are known as a major source of TA(thermal asperity). Researchers have investigated how particles induce the TA phenomena, but have not verified yet the reason why and how particles are generated in a HDD. The objective of this study is to investigate why and how particles are generated, and in what condition, the largest number of particles is generated. The number of particles generated in a HDD was measured over the landing zone after various rest times of slider and during various motions and positions of slider. It is found that the large number of particles was generated when the HDD was turned on after a long rest time of slider and that a few of particles were continuously generated when the slider flied over the disk surface. It is thought that the number of particles generated in a HDD was related to the rest time of slider because the rest time of slider increased stiction, and that there were intermittent contacts between the slider and the disk surface when the slider flied over the disk surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.985-990
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• 2003

With the rotational speed of the hard disk drive (HDD) increased, the low frequency structural vibration induced by the unbalance force gives rise to the structure home noise of the personal computer, and finally degrades the noise quality. As the unbalance of the hard disk drive is decided by the mechanical assembly allowance between clamping and platter disk, there is limit to control this unbalance by the improved assembly method. To improve the noise and vibration performance of PC, basically the unbalance of HDD needs to be measured absolutely and reduced during the stage of the disk assembly. This study introduces the HDD unbalance measurement methods of the absolute magnitude based on the mobility concept, and the unbalance location information with the acceleration orbit.

• Tribology and Lubricants
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• v.19 no.5
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• pp.292-297
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• 2003

The fundamental fluid mechanics associated with the rotation of a smooth plane disk enclosed within a cylindrical chamber have been studied experimentally. In order to acquire systematic information pertinent to this problem torque and friction loss data were obtained over a wide range of disk Reynolds numbers for axial clearance-disk radius ratio H/R from 0.025 to 0.2 and radial tip gap-disk radius ratio s/R from 0.021 to 0.105. Loss analysis of hard disk drive (HDD) is presented to describe the contribution of windage loss of a rotating disk. The minimum loss form factor of HDD can be obtained from this analysis at each operation conditions.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.159-165
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• 2001

The fundamental fluid mechanics associated with the rotation of a smooth plane disk enclosed within a cylindrical chamber have been studied experimentally. In order to acquire systematic information pertinent to this problem torque and friction loss data were obtained over a wide range of disk Reynolds numbers for axial clearance-disk radius ratio H/R from 0.025 to 0.2 and radial tip gap-disk radius ratio s/R from 0.021 to 0.105. Loss analysis of hard disk drive(HDD) is presented to describe the contribution of windage loss of a rotating disk. The minimum loss from factor of HDD can be obtained from this analysis at each operation conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.274-276
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• 2010

Three noise sources are come from note PC system; HDD, System Cooling Fan and ODD. Except HDD, user can accept as an acceptable operating noise. System Fan needs to cooling down the CPU and Chipset and ODD only works when it need to work, therefore user thinks these two noise sources are necessary. For the HDD, some times it makes noise without user HDD access action such as re-organizing cache and defragmentation, user can hardly accept this noise. At the circumstance like as library and the room at the dawn, user can recognize the noise easily so that makes dissatisfaction. I'm studying algorithm and method to reduce HDD noise for user satisfaction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.122-127
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• 2002

A frequency-domain PES estimation and its prediction method are proposed for the tightly-coupled servo/mechanical design of high-TPI HDD system above 100 kTPI. The major two disturbance energies which are related with mechanical vibrations inside of HDD are used to predict the drive-level PES, while considering closed-loop servo dynamics. One is the torque disturbance which mainly comes from aerodynamic excitation of HSA system and the other is the displacement disturbance from disk-spindle dynamics. In order to obtain the accurate error transfer function of closed-loop servo control, the plant model is measured by accurate experiment. The measured PES is compared with predicted one in terms of frequency-domain PES spectrum and its standard variation value. It is proved that the proposed frequency-domain PES estimation/prediction method is capable of predicting drive-level PES of high-TPI hard disk drive.

• Journal of KSNVE
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• v.5 no.2
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• pp.163-168
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• 1995

A criterion for the selection of spindle motor speeds in a hard disk drive (HDD) is investigated to guarantee stability and reduce nonrepeatable runout of a spining disk. Since the natural frequencies of the spining disk and the forced frequencies generated from the spindle motor depend on the rotating speed, careful consideration should be taken to avoid the resonance between the disk and motor. To do this, the natural frequencies of the spining disk are calculated and they are compared with the forced frequencies from the spindle motor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.6
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• pp.94-101
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• 2007

In the Hard Disk Drive(HDD) production, the detect pattern or defective HDD set is important information to diagnosis of defective HDD set. This paper proposes a pattern recognition neural network for the defect distribution of HDD. In this paper, 5 characteristics are determined for the classification to six standard defect pattern classes. A multi-layer perceptron is trained for the pattern classification the inputs of which are 5 characteristic values and the 6 outputs are the nodes of standard patterns. The experiment with proposed neural network shows satisfactory results.

• Transactions of the Society of Information Storage Systems
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• v.6 no.2
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• pp.41-46
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• 2010

Recently, Flash Memory Drives are one of the best media to support portable and desktop computers' storage devices. Their features include non-volatility, low power consumption, and fast access time for read operations, which are sufficient to present flash memories as major database storage components for desktop and server computers. However, we need to improve traditional storage management schemes based on HDD(Hard Disk Drive) and RAID(Redundant Array of Independent Disks) due to the relatively slow or freezing characteristics of write operations of SSDs, as compared to fast read operations. In order to achieve this goal, we propose a new storage management scheme called Hetero-Mirroring based on traditional HDD mirroring scheme. Hetero-Mirroring-based storage management improves RAID-1 operation performance by balancing write-workloads and delaying write operations to avoid SSD freezing.