• Transactions of the Society of Information Storage Systems
• /
• v.2 no.1
• /
• pp.21-25
• /
• 2006

The new multimedia information environment requires smaller optical data storage systems. However, one of the difficulties encountered in designing small form factor(SFF) optical pick-up is to emit the heat which is generated from laser diode(LD). Heat generated at the LD can reduce the optical performance of the system and the lifetime of LD. Therefore, it is important to include the thermal design in the design stage of SFF optical pick-up system for high performance and the longer lifetime of LD, and furthermore, to analyze the thermal characteristics of LD in detail micro heat transfer analysis is necessary. In the present study, micro heat transfer analysis was performed using the finite element method for the $28{\times}11{\times}2mm^3$ super slim swing-arm type optical pick-up actuator for Blu-ray disk. Two different materials were used for a swing-arm; a double layer polycarbonate/steel structure and a single aluminum structure.

• Transactions of the Society of Information Storage Systems
• /
• v.3 no.1
• /
• pp.1-4
• /
• 2007

A high density optical data storage device has been required for many years. In the field of the optical data storage, a near-field recording (NFR) technology is considered as a next generation one for achieving the high data density. Due to an evanescent wave effect occurred under 100nm distance which is the excessively small distance between the SIL and the disc, the most significant and difficult problem in this technology is to maintain a gap between a solid immersion lens (SIL) and a disc. Also, maintaining the gap under at least 50nm is required in the NFR gap servo system to use the evanescent wave effect efficiently. There are some institutes that have shown the novel gap servo control. In general, they use a mode switching servo method which consists of approach, hand-over and gap control mode. However there is a critical problem such as an overshoot at the tuning point from the approach mode to the hand-over mode, which may cause a collision between the SIL and the disc. In this paper, we show our NFR system and an improved gap servo system using an exponential function as the approach mode which can reduce the overshoot.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.742-747
• /
• 2000

The optical storage device has recently experienced significant improvements, especially for the aspects of high capacity and fast transfer rate. However, it is the fact that the optical storage device has the lower access time for the randomly scattered data compared to the hard disk drives. It is, therefore, necessary to develop a new type of optical storage system. In this study, we investigate the air bearing characteristics for the optical disk drives which have the swing arm actuator similarly to the hard disk drives. Considering the requirements of the optical disk drives, we parametrize the shape of the air bearing surface and investigate its sensitivity to the flying characteristics for further optimized design outputs.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.8
• /
• pp.174-181
• /
• 2001

Nowadays, the improvement and development of Multi-media and information & communication technology is rapidly processed. They need large data storage capacity. So that, many studies and researches in data storage have been carried out. According to them, the data storage capacity has been increased. But the limitation of storage capacity is happened for several problems. One of them is spot & pit size in optical and magnetic data storage and another is the resolution of actuators. The problems in spot & pit size are covered by new data storage methods-- for examples, AFM(Atomic Force Microscopy), MO(Magneto-optical) system, and NFR(Near-Field decoding) system etc. But the resolution limit of an actuator was not developed and doesn\`t follow up the development of spot & pit size. Because of them, we should improve a resolution of an actuator. Especially, in this paper an actuator if studied and designed for NFR (in using SIL(Solid Immersion Lens) system. It is a dual stage actuator, which consists of a Fine actuator and a Coarse actuator. and should desire 100nm accuracy. Its actuating force generation method is VCM(Voice Coil Motor). The Fine actuator is composed of 4-leaf springs and a bobbin wrapped by coil. The Coarse actuator has Coils and 3-Roller bearings. Also, The Characteristics of designed actuator for NFR system is estimated by Sine-Swept mode and LDV(Laser Doppler Vibro-meter).

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

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

• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.1256-1258
• /
• 1993

Optical data storage offer high density storage and archival storage capability. In this study, we selected the ablation mechanism-one of an irreversible recording system-using the antireflection trilayer(ART) structure. Optical recording medium is a $(Te_{86}Se_{14})_{50}Bi_{50}$ thin films. Actually, ART structure is fabricated and compared to monolayer structure. ART structure leads to the reduction of recording power as well as an increase in the effciency compared to the monolayer structure.

• Transactions of the Society of Information Storage Systems
• /
• v.1 no.1
• /
• pp.93-98
• /
• 2005

Rewritable optical disk is one of the essential data storage media in these days, which takes advantage of the different optical properties in the amorphous and crystalline states of phase change materials. As well known, data transfer rate is one of the most important parameter of the phase change optical disks, which is mostly limited by the crystallization speed of recording media. Therefore, we doped Sn/Bi to $Ge_2Sb_2Te_5$ alloy in order to improve the crystallization speed and investigated the dependence of phase change characteristics on Sn/Bi doping concentration. The Sn/Bi doped $Ge_2Sb_2Te_5$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, UV-visible spectrophotometer, electron probe microanalysis (EPMA), inductively coupled plasma mass spectrometer (ICP-MS) and atomic force microscopy (AFM). Optimum doping concentration of Bi and Sn were 5${\~}$6 at.$\%$ and the minimum time for crystallization was below than 20 ns. This improvement is correlated with the simple crystalline structure of Sn/Bi doped $Ge_2Sb_2Te_5$ and the reduced activation barrier arising from Sn/Bi doping. The results indicate that Sn/Bi might play an important role in the transformation kinetics of phase change materials..

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

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.12
• /
• pp.209-216
• /
• 2010

Optical Temperature Distribution Sensor Measurement System uses fiber optic sensors itself for temperature measurement is a system which can be measured the Installed surrounding entire temperature as a thousand points by laying a single strand of fiber optic. If there are a lot of measuring points in the distribution Measurement, the cost of each measuring point can be reduced the cost level of existing sensors and at the same time this has the advantage of connecting all sensors as one or two strands of fiber. Generally Optical Fiber is used for communication but Optical Fiber itself can be used for sensor and it has the characteristic of sensor function which can be measured Temperature in the at least each one meter distance. By using these characteristics each sensor and the number of Connection Lines can be reduced. In this paper, we implement a real time temperature monitoring system, which is easy to manage and control for data storage, data management, data storage using a computer and which has the functions of monitoring and correction according to Real-time temperature changes using historical temperature data.