• Journal of Institute of Control, Robotics and Systems
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• v.15 no.7
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• pp.683-687
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• 2009

Track jump control is a random access strategy for short distance movement. The most common track jump scheme is a bang-bang control of a kick and brake manner. In a conventional track jump scheme, a track-following compensator is turned off during kick and brake periods, and restarted at a target track for track pull-in. The inevitable controller switching with non-zero initial condition results in undesirable transient response, and excessive overshoot in the transient response causes track pull-in failure. In this paper, a new track jump scheme is proposed for enhancing track jump stability. Instead of control switching, internal states of a track-following controller are artificially manipulated for kick and brake actions in a digital control environment. Experimental results are provided in comparison with conventional track jumps.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.398.1-398
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• 2002

A new type actuator has been designed and investigated to overcome thermal problems in slim optical disc drives adopted in mobile storage devices. As the size of optical disc drives decreases, it is more difficult to remove the heat inside a drive and the temperature of an actuator increases. As a result, the second resonance of an actuator moves down to a lower frequency band and the performance of optical parts also deteriorates. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.397.1-397
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• 2002

For high density optical storage, there should be a high NA objective lens and a shorter wavelength laser diode. To secure the disc tilt margin related to the coma aberration, moreover, it's difficult to apply the tilt compensation mechanism into the portable PC. In this paper, we proposed the 3-axis asymmetry pickup actuator with high efficiency symmetric magnetic circuit, which consisted of the top cover type inner yoke for high magnetic flux density, the coil stack unit for the 3-axis independent operation and vertically polarized magnets. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.961-966
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• 2001

The schematic design process is formulated to develop the vibroisolating rubber mount in optical disc drives. The dynamic model of vibration isolation system is established by using a rigid body with 6 degree of freedom and linear springs with damping property. Considering the practical vibration condition of DVDP(Digital Versatile Disk Player), the required properties of vibroisolating rubber mounts are investigated. Also finite element model of a vibroisolating rubber mount is used to obtain shape design concept and identify the characteristics of a rubber mount which satisfies the required properties from previous design stage. Finally the evaluation method of dynamic properties of vibroisolating rubber mounts is established by utilizing modal test method. Based on the developed process, vibroisolating rubber mounts with a good performance have been developed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.813-819
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• 2006

The state of the art for the design of swing ann actuators for optical disc drives is to obtain the high efficient dynamic characteristics, especially for the small size for the mobile information devices, It is affected by the need of consumers who wants the portable digital storage devices maintaining highly functional and removable characteristics of the optical disk drive (ODD). As a necessary consequence, the need of the small form factor (SFF) storage device has been considered as an important part in the information storage technology. In this paper. we suggest a new conceptual miniaturized swing arm type actuator that has high efficient dynamic characteristics as well as satisfies the sensitivity and the heat emission requirements for the SFF-ODD. It also uses a tracking electromagnetic (EM) circuit for a focusing motion. Due to the size constraint, the thermal problem of optical head arises; therefore, we design an efficiently heat emitted structure for the actuator.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.684-687
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• 2002

In optical disk drive(ODD), pickup actuator, which comprises a key part of an optical disk drive equipment. must be thin. compact, and high sensitive. Low tilt is also an important requirement for the actuator, since optical disks are to high density. This tilt occurs from around the axis parallel to the tangential and radial direction of the disk. The main reason of the moment is the coupling effect between focus driving system and tracking driving system. This paper analyzed tut quantity due to focusing and tracking force through coupled fields analysts with electromagnetic analysis and structural analysis.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.831-833
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• 2003

BLDC (Blush-Less Direct Current) motors are widely used for machine tools and ODD (Optic Disc Drive). Topology Optimization is applied to the rotor of a BLDC motor to improve in efficiency and save money. Density method and design sensitivity are derived. The result of topology optimization shows better performance.

• Journal of Information Management
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• v.21 no.2
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• pp.9-23
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• 1990

CD-ROM technique, not more than 10 years after development, goes through rapid growth, has been taken advantage of several practical application parts. Needless to say about bibliographic data, numeric value, the phonetics, an image and a picture data that are recorded as abstract or full text, and offered and applied to industry, information service including library, it can be used for library staffs, information retrieval. Escape from the need of one disc drive and one computer to access one disc, now we organize an ideal system that can be retrieved several CD-ROM used only one drive, several users can access several information, so networking is possible through LAN. In this article, we studied the function and type, characteristics, system, structure, data block, production procedure, standardization of CD-ROM LAN.

• Journal of Digital Contents Society
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• v.14 no.1
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• pp.15-23
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• 2013

In response to the demands of large-scale data processing with low-power and new application, a storage system using SSD (Solid State Disk/Drive) with fast input-output performance instead of hard disc has appeared as storage device. Studies on methods to overcome specific problems of SSD such as various processing data units, out-place-update and limited delete count have been actively conducted. However, declining performance and stability have not been resolved yet when storing case specific data with small scale that causes frequent random write in hard disc or SSD. This thesis suggests a system structure that stores index requesting frequent random write in NVRAM capable of byte access by using characteristics such as byte unit fast read / write of NVRAM, non-volatile and smaller size of actual changed data size in index page than block size.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1296-1299
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• 2002

We implemented a CD signal processor operated on a CAV 48-speed CD-ROM drive into a VLSI. The CD signal processor is a mixed mode monolithic IC including servo-processor, data recovery, data-processor, and I-bit DAC. For servo signal processing, we included a DSP core, while, for CAV mode playback, we adopted a PLL with a wide recovery range. Data processor (DP) was designed to meet the yellow book specification.［2］So, the DP block consists of EFM demodulator, C1/C2 ECC block, audio processor and a block transferring data to an ATAPI chip. A modified Euclid's algorithm was used as a key equation solver for the ECC block To achieve the high-speed decoding, the RS decoder is operated by a pipelined method. Audio playability is increased by playing a CD-DA disc at the speed of 12X or 16X. For this, subcode sync and data are processed in the same way as main data processing. The overall performance of IC is verified by measuring a transfer rate from the innermost area of disc to the outermost area. At 48-speed, the operating frequency is 210 ㎒, and this chip is fabricated by 0.35 um STD90 cell library of Samsung Electronics.