• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.260.1-260.1
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• 2007

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.229-234
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• 2005

A novel method to measure the interaction movement, focusing direction and tracking direction in an optical pick-up, is proposed and the decoupling control for it is discussed. First, the basic principle of the coupline analysis method using back electromotive farce is introduced. Second, the interaction analysis between focusing direction and tracking direction fur commercial slim type actuator is performed using the proposed method. Finally, the coupling analysis and decoupling control for the slim type optical pick-up are discussed. From the brief simulation, we shows that the effectiveness and validity of the proposed method.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.259.1-259.1
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• 2007

• 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.

• BMB Reports
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• v.57 no.5
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• pp.256-261
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• 2024

In the context of aging, the susceptibility to infectious diseases increases, leading to heightened morbidity and mortality. This phenomenon, termed immunosenescence, is characterized by dysregulation in the aging immune system, including abnormal alterations in lymphocyte composition, elevated basal inflammation, and the accumulation of senescent T cells. Such changes contribute to increased autoimmune diseases, enhanced infection severity, and reduced responsiveness to vaccines. Utilizing aging animal models becomes imperative for a comprehensive understanding of immunosenescence, given the complexity of aging as a physiological process in living organisms. Our investigation focuses on Cisd2, a causative gene for Wolfram syndrome, to elucidate on immunosenescence. Cisd2 knockout (KO) mice, serving as a model for premature aging, exhibit a shortened lifespan with early onset of aging-related features, such as decreased bone density, hair loss, depigmentation, and optic nerve degeneration. Intriguingly, we found that the Cisd2 KO mice present a higher number of neutrophils in the blood; however, isolated neutrophils from these mice display functional defects. Through mass spectrometry analysis, we identified an interaction between Cisd2 and Calnexin, a protein known for its role in protein quality control. Beyond this function, Calnexin also regulates calcium homeostasis through interaction with sarcoendoplasmic reticulum calcium transport ATPase (SERCA). Our study proposes that Cisd2 modulates calcium homeostasis via its interaction with Calnexin and SERCA, consequently influencing neutrophil functions.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.139-144
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• 2005

Because of the photorefractive recording dynamics, each newly recorded hologram partially erases all previously stored image. Thus achieving the desired diffraction efficiency profile for the entire sequence after all images have been recorded requires exposure time schedule. The often cited classical exposure-schedule model predicts a rising-exponential build-up and an exponential decay in An with an exposure time. However because we cannot directly measure the An, it's difficult to establish the relation of both. In this paper, we deduce the relation of diffraction efficiency and exposure time from experiment data and suggest an algorithm to make time schedule profile in angle/fractal multiplexing of holographic data storage. After that, we present simulated result with equal hologram diffraction efficiency for a sequence of 250 holograms recorded by angle/fractal multiplexing.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.129-133
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• 2005

Data storage related with writing and retrieving requires high storage capacity, fast transfer rate and less access time. Today any data storage system cannot satisfy these conditions, however holographic data storage system can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System can be constructed without mechanical actuating part therefore fast data transfer rate and high storage capacity about $1Tb/cm^3$ can be realized. In this paper, to reduce errors of binary data stored in holographic data storage system, a new method for bit error reduction is suggested. First, find cluster centers using subtractive clustering algorithm then reduce intensities of pixels around cluster centers and fuzzy rules. Therefore, By using this error reduction method following results are obtained ; the effect of Inter Pixel Interference noise is decreased and the intensity profile of data page becomes uniform therefore the better data storage system can be constructed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.75-78
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• 2004

In an optical disk drive, a feeding system which is used to move the optical pick-up system to the target position and the proper control scheme of it are important in random access performance. Since the effect of control is directly affected by the modeling precision of the real system, the precise modeling to the real system should be acquired. Although a simple linear order modeling to the feeding system of an optical disk drive is useful in understanding of the overall dynamic characteristics, the dynamic characteristics which are belongs to the nonlinear area cannot be predicted correctly. Furthermore, the feeding system of an optical disk drive has many nonlinear characteristics such as a nonlinear friction and backlash. For this reason, the understanding of the nonlinear properties in the feeding system is very important. In this paper, the nonlinear items of the feeding system, friction and backlash, are introduced and the effect of it are investigated. Finally, the mathematical model considering the nonlinear properties is compared to the real system, and some comments of it are given.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.475-480
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• 2000

A new positioning mechanism with Parallel type actuator using piezoelectric material and with dual type actuators using voice coil motor (VCM) and piezoactuator is proposed for optical disk drive or near-field recording type drive, and high speed position and vibration control are investigated. Parallel type bimorph piezoactuator is used as a fine motion actuator with self-sensing technique, which allows a piezoelectric material to concurrently sense and actuate in a closed loop frame work, and positive position feedback control algorithm is adopted to further control residual vibration. For positioning control of VCM, PID control algorithm is adopted.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.440-445
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• 2000

Robust tracking controller of optical disk drive(ODD) is designed using quantitative feedback theory(QFT). Nominal plant model is identified from real system through modal test. Uncertainties and control performance of tracking servo are specified, and robust controller satisfying these specifications is designed in the QFT framework. To verify the performances of designed controller, experiment are performed in a digital signal processor(DSP) environment, and experimental results are compared with simulations.