• Transactions of the Society of Information Storage Systems
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• v.6 no.1
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• pp.25-30
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• 2010

In this paper, we investigate the confocal filter for high quality reading signal of micro holographic data storage system. The confocal filter is used to remove crosstalk effects of adjacent recording-layer by multi-layer multiplexing method. To remove a noise of reading signal, we consider size and geometrical structure of filter. From the obtained results, we present optical characteristics including Fresnel and Fraunhofer diffraction effects. Finally, we propose the optimal confocal filter for good image quality and increased reflection power.

• The Transactions of the Korea Information Processing Society
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• v.6 no.7
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• pp.1724-1737
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• 1999

Multimedia data service applications have to store and manipulate LOBs(unstructured large objects) composing multimedia data. As such, the tertiary storage devices such as an optical disk jukebox and a tape library that consist of a number of platters (the disks in case of an optical disk jukebox and the cartridge tapes in case of a tape library) have been considered essential for the storage system of a DBMS in order to efficiently support storage and management of vary large volume of data. Since the latency with tertiary storage is too long, the schemes for efficient retrieval of LOBs out of tertiary storage need to be investigated. In this paper, we investigated the tertiary I/O Considering the performance characteristics of the LOBs, we proposed various I/O scheduling heuristic algorithms that reduce latency in query processing with LOB retrieval from tertiary storage, and evaluated their performance through a detailed simulation.

• Transactions of the Society of Information Storage Systems
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• v.2 no.1
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• pp.43-49
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• 2006

Fractal/angle multiplexing is a $LiNBO_3$ crystal using a X-Y Galvano mirror, and the random access concept in fractal/angle multiplexing are discussed in this paper. First, the brief introduction of the designed holographic digital data storage system is presented. Then, the average access time concept for the storage system is newly defined, and the comparison of the average access time between the holographic storage and a conventional optical disk is performed. Second, the basic simulation and experiment to find the X-Y Galvano mirror dynamics are conducted. From this analysis, we find that the average access time in our HDDS which has 6 degree scan angle is about 5 msec. This result is very high performance when it compared with the average access time of a conventional optical disk. Finally, some recording results using fractal/angle multiplexing are presented, then, the relationship between bit error rate and angle mismatch for the each multiplexing are discussed.

• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.241-244
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• 1997

A speckle pattern from an optical fiber is used for a reference beam in writing and reading a volume hologram. The photorefractive volume hologram with this scheme shows good spatial selectivity for spatial(shift) multiplexing because the speckle pattern in writing and reading a hologram looses correlation with a small spatial shift. This scheme has the insensitivity to axial movement. The data storage system with this scheme will have a high storage density and a good stability in operation. We theoretically analyze the diffracted beam from a volume hologram recorded with the speckle pattern from the optical fiber. Experimental results are presented and compared with numerical analysis.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.289-292
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• 1999

Random reference wave can be used to enhance selectivity and storage density of holograms. Hologram recording schemes with random reference waves generated by using a ground glass or various types of optical fibers are discussed. The random reference waves are also suitable for hybrid multiplexing methods.

• Proceedings of the Korea Database Society Conference
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• 1998.09a
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• pp.3-48
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• 1998

Drivers for Increased Need for Digital Content ■ Falling cost of computing -Multimedia capability at reasonable cost ■ Decrease in digital storage cost -Magnetic, optical and tape -Cost of digital storage decreases 40％ / year ■ World Wide Web users explosion and falling cost of communications -17M web servers(1/97) -Number of users doubles every 6 months - Network bandwidth triples every year(omitted)

• Korean Journal of Optics and Photonics
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• v.13 no.6
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• pp.486-492
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• 2002

In this paper. we presented 1 & 2 dimensional minimum mean-squared-error (MMSE) equalization scheme in a digital holographic data storage system to improve bit-error-rate (BER) and to mitigate inter-symbol interference (ISI) which were generated during the data storage and retrieval processes. We showed experimentally for ten data pages retrieved from the holographic storage system that BER and signal-to-noise ratio (SNR) were improved by adopting MMSE equalization.

• Journal of Korean Library and Information Science Society
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• v.34 no.2
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• pp.187-207
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• 2003

With the rapidly evolving information technologies and the Internet, a network-based storage management system is required that can efficiently save, search, modify, and manage digital contents which are increasing by geometric progression. Recently, the SAN became highlighted as a solution to such issues as the integrated data management for heterogeneous systems, the effective utilization of storage systems, and the limitation of data transfer. SAN allows for effective management and sharing of bulk data by directly connecting the storage systems, which used to be independently connected to servers, to the high-speed networks such as optical channels. In this study, I researched on the technologies, standardization and market trends of storage management systems, and performed comparative analyses of the structures, components, and performances for achieving the integration of diverse system storage systems as well as the virtualization of storage systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.848-851
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• 2007

Recently, as the demand of the information storage devices with large storage capacity such as BD(Blu-ray Disk) and HDTV(high-definition television) is increased, the optical storage devices are also required to have fast data transfer rate and large storage capacity. To satisfy these requirements, the actuator for optical disk drive should have high flexible mode frequencies for system stability. In this paper, we suggested a moving magnet type actuator having high flexible mode frequency. However, the moving magnet type actuator does not have sufficient driving sensitivities due to the weight of its moving part. To improve driving sensitivities, we designed the model with the closed electromagnetic circuit for tracking direction. In addition, driving sensitivities and flexible mode frequencies were improved by using DOE(Design of Experiments) for magnetic circuit and modifying the lens holder. Consequently, it is confirmed that the designed model is satisfied with the desired specifications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11C
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• pp.1052-1057
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• 2006

The implement the adaptive partial response maximum likelihood (PRML) detector with tilt analyzer for asymmetric high-density optical storage system. For the estimation of disc tilt, we exploit spc patterns in each data frame. Because of using the ROM table to renew the coefficients of equalizer and reference values of branches, the complexity of the hardware is reduced. The proposed PRML has been designed and verified by VerilogHDL and synthesized by the Synopsys Design Compiler with Hynix $0.35{\mu}m$ STD cell library. In the result, the total gate count is 35K, and the maximum operating frequency is 140MHz.