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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Society of Information Storage Systems
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The Society of Information Storage Systems
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Volume 3, Issue 4 - Dec 2007
Volume 3, Issue 3 - Sep 2007
Volume 3, Issue 2 - Jun 2007
Volume 3, Issue 1 - Mar 2007
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Image Compensation Algorithm for Holographic Data Storage System
Jung, Kyu-Il ; Moon, Jin-Bae ; Park, Joo-Youn ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 154~159
Measurement of the Slider-Disk Contact during Load/Unload process with AE and Electrical Resistance
Kim, Seok-Hwan ; Lee, Yong-Hyun ; Lim, Soo-Cheol ; Park, Kyoung-Su ; Park, No-Cheol ; Park, Young-Pil ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 160~166
In this paper, the measured electrical resistance method is proposed to analyze the ramp-tab contact during the load/unload (L/UL) process. Since this method supplies the voltage change due to the resistance change, we can easily and conveniently identify the ramp-tab contact from the acoustic emission (AE) signal. At first, we carefully deposit the conductive material on the surface of the conventional ramp by sputtering method. The ratio frequency (RF) magnetron co-sputtering system is applied to accomplish the deposited double-layers on the ramp surface. One layer is the stainless steel for the conductive layer and the other is the titanium layer for the cohesive function between the ramp surface and the stainless steel layer. In order to guarantee the stiffness and damping properties of the original ramp, the deposited conductive layer is intended to have very thin thickness. After integration the proposed ramp device into the L/UL system and networking the electrical resistance circuit, the L/UL performance is experimentally evaluated by comparing the measured electrical resistance signal and AE signal.
A Fast Off-line Learning Approach to the Rejection of Periodic Disturbances
Chang, Jung-Kook ; Kim, Nam-Guk ; Lee, Ho-Seong ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 167~172
The recently-developed off-line learning control approaches for the rejection of periodic disturbances utilize the specific property that the learning system tends to oscillate in steady state. Unfortunately, the prior works have not clarified how closely the learning system should approach the steady state to achieve the rejection of periodic disturbances to satisfactory level. In this paper, we address this issue extensively for the class of linear systems. We also attempt to remove the effect of other aperiodic disturbances on the rejection of the periodic disturbances effectively. In fact, the proposed learning control algorithm can provide very fast convergence performance in the presence of aperiodic disturbance. The effectiveness and practicality of our work is demonstrated through mathematical performance analysis as well as various simulation results.
Characterization of Photopolymers films containing triazine methacrylate monomer for photochromic diffractive image formation
Oh, Hyun-Jin ; Lee, Ji-Yea ; kim, Eun-Kyoung ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 173~177
A photo-reactive methacrylate monomer having triazine as a core component was examined for photochromic diffractive image formation. Photochromic photopolymer films as a recording media contained a monomer mixture of triazine difunctional metharylate (DT) and ethylene glycol phenyl ether acrylate, binder polymer, photo initiator, and a photochromic spiro-oxazine dye. The content of photochromic dye was changed to examine the effect of photochromophore on diffraction efficiency and real holographic image formation. Holographic recording was performed on the photopolymer film by the combination of reference and probe beam. The diffraction efficiency of the photopolymer film in real-time measurement reached a maximum of
within 30s. It was highly dependent on the photochromophore contents. After holographic recording, the color of the recorded area was changed under UV light (365 nm) and reversibly bleached to original color upon exposure to a visible light source. Films containing only photochromophore without monomer mixture were not reactive under the recording beam (491nm). Diffractive image formation and mechanism of the holographic recording in the presence of photochromophore will be presented.
Sequential Design of Experiment Based Topology Optimization
Song, Chi-Oh ; Park, Soon-Ok ; Yoo, Jeong-Hoon ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 178~182
Topology optimization methods are classified into two methods such as the density method and the homogenization method. Those methods need to consider relationships between the material property and the density of each element in a design domain, the relaxation of the design space, etc. However, it is hard to apply on some cases due to the complexity to compose the design objective and its sensitivity analysis. In this paper, a modified topology optimization is proposed to assist designers who do not have mathematical or theoretical background of the topology optimization. In this study, optimal topology of structures can be achieved by the sequential design of experiment (DOE) and the sensitivity analysis. We conducted the DOE with an orthogonal array and the sensitivity analysis of design variables to determine sensitive variables used for connectivity between elements. The modified topology optimization method has advantages such as freedom from penalizing intermediate values and easy application with basic DOE concept.
Design and Analysis of Disk Bump to Improve the Unloading Performance in HDD
Lee, Yong-Eun ; Lee, Yong-Hyun ; Lee, Hyung-Jun ; Park, No-Cheol ; Park, Kyoung-Su ; Park, Young-Pil ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 183~190
In most hard disk drives that apply the ramp load/unload technology, the head is unloaded at the outer edge of the disk while the disk is rotating. During the unloading process, slider-disk contacts may occur by lift-off force and rebound of the slider. The main issue of this paper is to prevent the slider-disk contact by rebound, and we apply a disk bump to the unloading process. To do so, first, the ranges of bump dimension are determined. Second, the stability of each bump is checked by dynamic simulation. Finally, unload simulations are performed for stable bump designs. As a result of these steps, the effect of the bump design and the position for the unloading performance were investigated. As a consequence, we propose the optimal bump design to improve the unloading performance. Furthermore, we can identify to remove rebound contact by applying a bump on disk during the unloading process.
Development of 3-axis Moving Magnet Type Actuator
Song, Myeong-Gyu ; Hur, Young-Jun ; Park, No-Cheol ; Yoo, Jeong-Hoon ; Park, Young-Pil ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 191~195
The optical disc drive has used a high NA objective lens and a shorter wavelength laser diode for high recording density. But high NA and shorter wavelength cause several margins to become short. Focusing and tracking servo has to be more accurate and active tilt compensation mechanism is also needed for coma aberration compensation. In this paper, we proposed 3-axis moving magnet type actuator. For 3-DOF motion, moving coil actuator has to be equipped with 6 wires for supplying 3 independent signals. However, moving magnet type actuator doesn't need to change the configuration of wires because coils are in stator. So, we added a tilt mechanism to the 2-axis moving magnet actuator which is designed in previous research. Addition of the tilt mechanism cuts down the focus sensitivity. So, maximization the tilting sensitivity and securing the focusing sensitivity are objectivities of this research. DOE (design of experiments) procedures of electromagnetic circuit are performed for parameter study and the optimization is also performed to maximize the tilt sensitivity. And then the final design is suggested and its performance is verified by FE simulation.
Reduction of Aerodynamic Noise for a High-Speed Slim-Type Optical Disk Drive by Applying the Principle of Resonator
Yang, Tae-Man ; Choi, Moon-Ho ; Rhim, Yoon-Chul ; Lee, In-Hwan ; Lee, Han-Beak ; Cha, Ik-Joo ;
Transactions of the Society of Information Storage Systems, volume 3, issue 4, 2007, Pages 196~201
As the demand for the lap-top computer has been increased, most users ask quiet environment to work comfortably. Therefore, noise problems of an ODD are of great interest. For the high speed ODD, the flow induced noise is caused by the turbulent flow, which is known to be a major source of overall noise of a slim type ODD. In this study, we introduce a new attempt to reduce the noise level using the concept of Helmholtz resonator.The experimental analysis is carried out for several cases at different resonance frequencies and different hole patterns. The results show reductions in the noise level from the acoustic noise absorption point of view.