• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.3
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• pp.206-214
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• 1991

Flow field in a hard disk drive has been predicted numerically. Theoretical model was constructed based on a commercially available hard disk drive with 40 Mega byte capacity. Since the gap between disk tip and shroud is not homogeneous in real hard disk drive, three kinds of gap size have been tested as computational model. The discussion has been made on the circumferential velocity, radial velocity, and pressure fields. As a result, the average shear stress on the disk surface was reduced as the gap size decreased. This means that the shroud should be designed compactly to reduce power consumption of the spindle motor.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.286-289
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• 1996

Two servo control algorithms are suggested to reduce the tracking error of a computer hard disk drive. One is the repetitive control to reduce the repeatable tracking error which is not explicitly taken into account in the design of a conventional controller. This algorithm was successfully applied to a commercial disk using a fixed point DSP. The other is the multi-rate sampling control which generates the control output between each sampling times since the sampling time of hard disk drives is limited. These algorithms were shown effectively to reduce tracking errors.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.649-650
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• 2008

In order to resolve mechanical limit in HDD, recently, the hybrid hard disk combining HDD and a flash memory was launched. In this paper, we propose a simulator for hybrid hard disk which considers redirection, flushing and spin-down function to complement the difference between HDD and hybrid hard disk. The simulator was implemented in linux kernel 2.6.20 by modifying system calls related with file system. The experiment shows that the power consumption of hybrid hard disk is 47% smaller than that of hard disk in laptop PC.

• Tribology and Lubricants
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• v.17 no.1
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• pp.1-9
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• 2001

Hard disk drives operate in various environmental conditions. Thus, it is necessary to assess the reliability of the head/disk interface under these conditions. In this work, stiction and acoustic emission signals were investigated under different temperature, humidity, and ambient pressure conditions. Also, track average amplitude was observed for disk failure in N$_2$environment. It is shown that failure of the head/disk interface occurs more readily at high temperature and low ambient pressure conditions.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.123-125
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• 2011

A SATA hard disk has been widely used in recent years and NCQ is one of its crucial features. Despite the development from IDE to SATA disk, there is still much room for improvement for a SATA disk. In addition, until now a hard disk is a black box to us and it is very hard to make research at the level of a disk controller. To enhance the performance of NCQ, we try to do I/O clustering over the requests, which combines multiple sequential requests into a single large one. To evaluate the effect of an I/O clustering mechanism, we created a simple but practical SATA hard disk simulator. Experimental results show that the proposed approach is effective in enhancing the I/O performance of a SATA disk.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.8 s.227
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• pp.976-983
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• 2004

In high-density hard disk drives, the slider should be made to fly close to the magnetic recording disk to generate better signal resolution and at an increasingly high velocity to achieve better data rate. The slider disk interaction in CSS (contact-start-stop) mode is an important source of particle generation. Contamination particles in the hard disk drive can cause serious problems including slider crash and thermal asperities. We investigated the number and the sizes of particles generated in the hard disk drive, operating at increasing disk rotational speeds, in the CSS mode. CNC (condensation nucleus counter) and PSS (particle size selector) were used for this investigation. In addition, we examined the particle components by using SEM (scanning electron microscopes), AES (auger electron spectroscopy), and TOF-SIMS (time of flight-secondary ions mass spectrometry). The increasing disk rotational speed directly affected the particle generation by slider disk interaction. The number of particles that were generated increased with the disk rotational speed. The particle generation rate increased rapidly at motor speeds above 8000 rpm. This increase may be due to the increased slider disk interaction. Particle sizes ranged from 14 to 200 nm. The particles generated by slider disk interaction came from the lubricant on the disk, coating layer of the disk, and also slider surface.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.5
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• pp.1059-1065
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• 2015

Hard disk passwords are commonly not well known. If the passwords are set, forensic investigators are not allowed to access data on hard disks, so they can be used to obstruct investigations. Expensive tools such as PC-3000 are necessary for unlocking such hard disk passwords. But it would be a burden on both organizations that should pay for these tools and forensic investigators that are unfamiliar with these tools. This paper discusses knowledge required for unlocking hard disk passwords and proposes methods for unlocking the passwords without high-priced tools. And with a vendor-specific method, this paper provides procedures for acquiring passwords and unlocking hard disk drives.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.716-720
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• 1996

In this work the surface damage mechanism of hard disk was investigated. Experiments were peformed to simulate the contact during start and stop. Evidence of significant surface damage appeared after 20,000 cycles. It was found that despite higher hardness, the slider showed more signs of damage than the disk. Optical microscopy showed that the surface was damaged by abrasive action as well as adhesion of wear debris.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.215-216
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• 2005

Nowadays, mobility as well as basic performances has been the important performance index of hard disk drive, It makes a system unstable to satisfy mobility, huge storage capacity and high transfer rate. Shock and vibration analysis has been important because hard disk drive could be exposed by external shock and vibration. The probability of this situation has been increasing. In this research, each component and the whole system of 2.5in HDD are made to a finite element model. Results of finite element analysis are compared with the results of experimental modal analysis. Shock analysis is executed for 2.5in hard disk drive.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.06a
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• pp.122-126
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• 2001

Magnetic hard disk drive is continually being pushed to reduce head-disk spacing for higher recording densities. The current minimum spacing between the air-bearing slider and disk has been reduced to under 15 nm. In this work, it was investigated if flying height could be lowered under the height of laser bumps. With the reduction of the spinning speed, the flying height was decreased under the height of laser bumps. When a head swept between landing zone and data zone, the head-disk impact was monitored using AE and friction signals. It is demonstrated that magnetic hard disk drive could be operated without tribological failures under the height of laser bumps.