• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2669-2672
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• 2003

This paper describes a new method of discrimination between the normal disc and the rewritable one. The conventional method of disc discrimination, using Focus error signal, has a heavy fluctuations. To achieve an accurate discrimination, in this paper, the sum of side beam［1］signal is used for that. A new approach is expected to improve the performance of disc discrimination as well as to reduce the signal variation almost by 50％. Techniques in this paper are applicable to the all types of optical disc player, such as CD (compact disc), VCD(Video-CD) and DVD (digital versatile disc) and any other optical disc players.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.194-198
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• 2000

최근 저장 장치로 많이 사용되고 있는 IBM PC의 CD-ROM(Compact Disc Read Only Memory)과 MP3(MPEG-1 Layer Ⅲ Audio) 디코더 칩을 이용하여 PC 작동과 관계없이 독립적으로 작동하는 CD-ROM 기반의 MP3 Player를 구현하였다. 여기서는 CD-ROM의 규격과 CD-ROM에 사용되는 ATAPI(AT Attachment Packet Interface) Format, MPEG-1 Layer Ⅲ의 오디오 부분에 대하여 알아보고 MP3 디코더 칩을 사용하여 CD-ROM에서 읽은 MP3 데이터즐 재생하는 방법을 취하였다. 이리하여 PC 자체로 MP3를 작동시키는 부하를 경감시키는 효과를 얻었다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.294-295
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• 2007

80년대 초에 개발된 CD(Compact Disc) Disc는 지난 27여 년간 급속한 발전을 하였다. 95년에 DVD가 발표되면서 영화 Title제작이 되어 우리는 안방에서 고화질의 DVD를 감상할 수 있었다. CD-R(Recordable) 로부터 시작된 기록 기술은 CD-RW를 거쳐 DVD-Recordable, DVD-ReWritable 및 DVD-RAM, Light Scribe등 거쳐 BD(Blu-Ray) 기술에 까지 이르게 되었다. 광 Disc 기술은 3가지 분야로 나눌 수 있다. 안정된 제어를 위한 Servo 기술, Mechanical 기술, PC와communication 할 수 있는 Interface 기술 등으로 나눌 수 있다. Servo 제어 기술은 다음과 같이 4가지 분야로 구성되어 있다. Focus Servo, Tracking Servo, Sled Servo, Spindle Servo. Disc 회전을 제어를 담당하고 있는 Spindle Servo Block에서는 Hall Sensor를 이용하여 Disc의 회전을 Count하여 Feedback 하였다. 그러나 갈수록 심화 되고 있는 가격 경쟁 상황에서 Hall Sensor를 대체하여 회전수를 Conut하는 방법이 필요 하였다. BEMF(역기전력)을 이용한 Zero Crossing 방법이 이를 대체 하였지만, Motor의 전기적인 특성 편차 등에 안정된 control이 안되어서, Motor를 관리하는 방법으로 진행되어 왔다. 이것은 생산 Loss로 이어져서 Hall Sensorless의 장점을 훼손하게 되었다..본 논문에서는 이러한 Sensorless Type Spindle Motor의 문제점에 대해 Common 단자를 이용하여 안정된 제어 방법을 제안 한다. less Type의 문제점인 초기 기동 문제를 Common 단자를 이용하여 안정되게 Spindle motor를 Control 하는 방법에 대해 연구 하고자 한다.

• Journal of KSNVE
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• v.9 no.2
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• pp.387-392
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• 1999

This paper presents design guidelines for the automatic ball balancer in CD/DVD systems with varying eccentricity. In these systems, the size of balancing balls should be limited by the restricted race space so that determination of the number and mass of balls should consider the radii of the race and the balls. In addition, the effects of viscosity and friction also should be taken into account for sufficient balancing. Based on the static equilibrium conditions, the number and mass of balls corresponding to the range of varying eccentricity have been determined. Dynamic simulation with viscosity and friction shows sufficient viscosity must exist to ensure stability and friction between balls and race must be minimized to guarantee accurate balancing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.378-380
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• 2002

There has been lower the tilt margin by the increase of coma aberration due to the reduction of wave-length and the increase of numerical aperture for high density recording. The RF signal degradation is increased as the decrease of tilt margin. To compensate the tilt margin, the optical pick-up actuator for high-speed CD/DVD re-writable system should be able to drive the radial-tilt motion. We announce that the 3-axis drive actuator for high-speed CD/DVD rewritable system. And what was more, the DC/AC sensitivities of this actuator are suitable fur the low-speed playability, the high-speed readability and the high-speed rewritability.

• Electrical & Electronic Materials
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• v.10 no.3
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• pp.289-294
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• 1997

디지탈 비디오 디스크의 약어로 지칭되는 DVD는 현대 과학이 이루어낸 레이저 광에 의한 정보의 기록과 재생을 한층 승화시킨 차세대 package형 광 기록 매체이다. 앞으로 이 제품군은 기존에 분리되어 있던 가전과 컴퓨터의 응용분야를 이어주는 교량역할을 할 새로운 개념의 상품으로 기대된다. 본 고에서는 DVD의 기술적 배경 및 이의 구현을 위해 활용된 요소기술, 그리고 미래기술로의 흐름에 관해 소개고자 한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.351-355
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• 1996

In optical disc system, lens actuator of 4-wire has unwanted moment which occurs tilt. The moment around the axis pallet to the tangential direction of the disk occurs to the moving part. when the moving part is moved in tracking direction and focus driving force is applied. This paper analyzed coupled effect due to the moment based on structural analysis and magnetic field analysis, both using finite element method.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.52-60
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• 1998

In optical disc system, 4-wire actuator has undesired tilt which degenerates the performance of RF signal. This tilt occurs from moment around the axis parallel to the tangential direction of the disk. The main reason of the moment is the coupling effect between focus driving system and tracking driving system. This paper constructed tilt mechanism and analyzed tilt quantity due to the moment based on structural analysis and magnetic field analysis. And the experiment about tilt was executed. The results were compared and discussed about the difference. Then, the design method for reducing tilt angle was suggested.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.679-682
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• 1998

This paper presents the VLSI implementation of RS(reed-solomon) decoder using the Modified Euclidean Algorithm(hereafter MEA) for DVD(Digital Versatile Disc) and CD(Compact Disc). The decoder has a capability of correcting 8-error or 16-erasure for DVD and 2-error or 4-erasure for CD. The technique of polynomial evaluation is introduced to realize syndrome calculation and a polynomial expansion circuit is developed to calculate the Forney syndrome polynomial and the erasure locator polynomial. Due to the property of our system with buffer memory, the MEA architecture can have a recursive structure which the number of basic operating cells can be reduced to one. We also proposed five criteria to determine an uncorrectable codeword in using the MEA. The overall architecture is a simple and regular and has a 4-stage pipelined structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.454-457
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• 1995

In optical disc system, tracking actuator is consisted of coarse actuator and fine tracking actuator. This, two-stage actuator, requires many devices and two servos for large stroke and precisional displacement. These complicate configuration increases moving mass. So dynamic characteristics become bad, that is, sensitivity of high frequency gain decrease. In this paper, frequency performance is willing to be better as so one dimensional tracking actuator is designed. In order to investigate the performance of the proposed tracking actuator, the Bode diagram is plotted with Dynamic analyzer and friction characteristic is explained. Finally, tracking error performance is ins investigated into 0.1 .mu.m resolution with MATLAB simulation.