• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.244-247
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• 2000

This paper deals with methods for partial response maximum-likelihood (PRML) detection and crosstalk cancellation. In accrodance with the demand for increased recording density, 20 gigabyte (Gbyte) digital versatile disk (DVD) ROM channel is considered. Channel is modelled to be close to real optical channel using DIFFRACT$\^$TM/. After comparing the spectral characteristics of various PR polynomials, P(D)=1＋D＋D$^2$＋D$^3$is proposed as a target PR. The performance of the system is illustrated under the condition that the readout signal is degraded by crosstalk, radial tilt and nonlinear distortions in optics. The experimental results show that crosstalk and nonlinear distortions degrade performance by about 2dB, respectively. We also show that when radial tilt is added to the crosstalk, the performance degradation assumes quite significant proprotions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.105-108
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• 2004

The effect of thermal deformation of optical pick-up due to laser diode(LD) and LD driving integrated circuit on the optical performance of digital versatile disk(DVD) optical system was analyzed using the finite element analysis with initial surface residual stress conditions, and results were compared with the measured results with holographic interferometry. Ray tracing was performed using the deformed configuration of optical system.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.28-29
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• 2000

최근, 통신, PC등의 보급과 함께, 메모리기기의 발전이 급속히 이루어 지고있다. 이 중에서 광기억장치는 기록 및 재생용량을 증가시키는 기술이 활발히 연구되어 왔다. 본고에서는 대용량기기의 대표적인 DVD(Digital Versatile Disc)에 있어서, 핵심광학기술로 각광을 받고있는 CD호환을 위한 환형(annular type) lens의 특성을 고찰하였다. 그리고, 반도체 메모리, Hard disk등도 고밀도연구가 지속적으로 연구되고있으며, 이에 대응되는 광기억장치의 기술로서 근접장 광학이 최근 활발히 연구되고있다. 근접장에 의한 고개구수를 달성하기 위한 효율적인 대물렌즈로서 종래의 굴절렌즈만이 아닌 반사광학계도 사용한 굴절-반사광학계 (Cata-dioptric Optics)를 응용한 Solid Immersion Mirror (SIM)에 관한 특성을 살펴보았다. (중략)

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.4
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• pp.167-174
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• 2008

As both a digital camera and a digital camcorder are popularized in recent years, UCC created by general users is also popularized. Unfortunately, according to that, the lack of privacy is also increasing more and more. The UCC is saved on the recordable media(Media) like DVD and deposited personally as well as distributed through Internet portal service. If you use Internet portal service to put up your contents, you can partially prevent the violation of privacy using security technologies such as authentication and illegal copy protection offered by internet portal service providers. Media also has technologies to control illegal copy. However, it is difficult to protect your privacy if your Media having personal contents is stolen or lost. Therefore, it is necessary to develope an additional security mechanism to guarantee privacy protection when you use Media. In this paper, we describe AACS framework for Media Security and propose improved AACS framework to control the access to personal contents saved on Media.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.1
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• pp.1-9
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• 2001

In this paper, the general research on the analysis of the vibration due to magnetic exciting force in the small brushless DC(BLDC) motor, which is used in the Digital Versatile Disk(DVD) ROM driving system, is performed. The first part of the study is the analysis of the magnetic exciting force in the air gap region. As a verification of the exciting force by numerical analysis, the magnetic exciting force distribution in the air gap region is computed by using Reluctance Network Method(RNM). In addition, the effect of the eccentricity on the magnetic exciting force is discussed. The other part of the research is the structural analysis of the rotor structure of the BLDC motor. The matural mode analysis of the rotor structure is performed, and the vibration response due to magnetic exciting force is found. As a result of the procedures, the basic estimation of the effect of the magnetic exciting force on the vibration of BLDC motor is suggested.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.115-120
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• 2005

As a popularity of a portable digital device such as a cellular phone, a digital camera and a MP3 player is spreading, the demand of the mobile storage device increases rapidly. A bluray technology using 405nm laser diode and objective lens having high NA(Numerical Aperture), 0.85, satisfies a miniaturization and a high capacity which are the requirements of the portable device. To develop SFFOP(small form factor optical pickup), it is prerequisite to minimize the number of optical components and establish evaluation and assembly method of micro optical pickup system as well as mass production method of micro optical component. To minimize optical elements of optical pickup, there have been many researches to use P-HOE(Polarized Holographic Optical Element) due to its extremely small size and versatile function. However, P-HOE is handled and assembled very accurately in SFFOP. In this paper, static error signal detection method is developed for an alignment of P-HOE in SFFOP. Using developed static error signal detection method, P-HOE can be aligned very accurately with real time result of static error signals of pickup such as FES(focusing error signal) and TES(Tracking Error Signal). The developed static error signal detection method is verified by the evaluation of commercialized DVD Pickup. And finally. developed static error signal detection method is applied for the assembly of P-HOE in SFFOP system satisfies specification of BD(Blu-ray Disk).