• Digital Contents
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• no.11 s.114
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• pp.92-95
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• 2002

DVD(Digital Versatile Disk)에 관한 관심이 고조되고 있다. DVD가 현재 침체기에 있는 PC시장을 활성화시킬 수 있는 구세주로 등극할 것으로 예상되면서다. 최근 시장조사기관 IDC와 일본 파이오니어의 공동 보고서에 의하면 DVD와 관련된 홈 시어터, DVD 레코딩, 비디오 편집 분야가 PC 시장의 새로운 변수로 작용하고 있다. DVD롬 드라이브를 통한 DVD영화 시청은 물론, 직접 캠코더로 촬영한 동영상을 편집하고 DVD로 굽는 일련의 작업을 PC를 통해 수행하는 소비자들이 빠른 속도로 증가하고 있다는 얘기다. 이에 따라 관련업계의 움직임이 바빠지고 있다. 특히 DVD 관련 업체들의 DVD 표준 규격 확보를 위한 경쟁은 전쟁을 방불케하고 있다. 현재 마쓰시타, 소니, 도시바, HP, 삼성, LG 등 주요 광 드라이브 업체들이 DVD-R/RW, DVD-RAM, DVD+R/RW 등 각기 다른 차세대 기록형 DVD 규격을 놓고 경쟁하고 있다. 표준 규격을 거머쥐는 쪽이 향후에 전개될 차세대 DVD 시장을 주도할 것으로 예상되기 때문이다. 본 고에서는 현재 제기되고 있는 기록형 DVD 표준화 동향을 중심으로 차세대 DVD시장을 진단해본다.

• Journal of KSNVE
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• v.11 no.3
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• pp.471-476
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• 2001

This paper focuses on the numerical prediction of airflow-induced sound in DVD drives. As a first step, computational fluid dynamics (CFD) is conducted to evaluate flow field characteristics due to the high-speed disk rotation, and to support the acoustic analysis. Acoustic analogy based on Ffowcs Wi1liams-Hawkings (FW-H) equation is adopted to predict aeroacoustic noise patterns. The integral solution for quadrupole volume source is included to identify the turbulence noise generated inside the DVD tray. The strength of sound pressure revel with respect to rotating speed is discussed to meet upfront demand on the high fidelity product development. The present study also focuses on the noise directivity and examines how much the sound noise is sensitive to change in rotating speed. Near-field noise is strongly affected by the flow field characteristic, which is caused by the complex shape of the tray. For a mid-field, the quadrupole noise play as a counterpart of thickness noise or loading noise, so it generates different sound noise Patterns compared with those in the near field.

• The monthly packaging world
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• s.170
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• pp.88-91
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• 2007

• Journal of the Korea Computer Industry Society
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• v.3 no.3
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• pp.391-406
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• 2002

In order to realize a practical VOD system, it is necessary for a high-capacity and cost-effective hierarchical VOD server based on tertiary storages such as DVD jukebox. In such a system, it is possible to transfer multiple streams to users by alternatively swapping DVDs using the fixed number of drives. But it takes a long time for loading DVD to a drive. In this paper, we propose a primitive pipelined loading mechanism for hiding the loading time to swap DVDs in a hierarchical VOD server based on DVD jukebox. We also propose a enhanced pipelined loading mechanism for increasing the maximum admittable streams with the fixed number of drives. The enhanced mechanism caches the initial segment of each stream on a disk storage allowing faster data transfer. The performance analysis shows that the proposed mechanisms can admit the maximum allowed stream capacity under the fixed number of disk drives.

• Journal of KSNVE
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• v.11 no.1
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• pp.49-56
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• 2001

In this paper, two plant models, of which one is newly developed and the other one is the conventional one, of the focus servo system of DVD drive are presented and a two-degree-of freedom controller consisted of Inverse dynamics feedforward and LQG/LTR feedback controller is designed. The newly developed plant model is used to design the feedforward controller and the conventional model is used for the design of feedback controller. The output of newly developed model is the displacement of objective lens and the output of conventional model is the focus error of the DVD focus servo system. The displacement of the objective lens is estimated by the dynamics model of the DVD focus servo system. The disturbance rejection performance of the two-degree-of freedom controller is compared with that of an LQG/LTR one.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.759-764
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• 2000

The accurate prediction of aeroacoustic analysis is necessary for designers to control and reduce airflow-induced sound pressure levels in high speed rotating DVD drives. This paper focuses on the numerical prediction of airflow-induced sound in DVD drives. Computational fluid dynamics(CFD) is first conducted to evaluate flow field characteristics due to the high-speed disk rotation, and to support the acoustic analysis. The acoustic analogy based on Ffowcs Williams-Hawkings(FW-H) equation is adopted to predict aeroacoustic noise patterns. The integral solution for quadrupole volume source is included to identify the turbulence noise generated inside the DVD tray. The strength of sound pressure level with respect to rotating speed is discussed to meet upfront demand on the high fidelity product development. The present study also focuses on the noise directivity and examines how much the sound noise is sensitive to change in rotating speed. Near-field noise is strongly affected by the flow field characteristic, which is caused by the complex shape of the tray. For a mid-field, the quadrupole noise play as a counterpart of thickness noise or loading noise, so it generates different sound noise patterns compared with those in the near field.

• The Optical Journal
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• v.11 no.6 s.64
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• pp.49-59
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• 1999

지난 호에 있어서 태전위부 박사(송하전기산업주식회사 광디스크개발센타)의 '광메모리' 강의(한$\cdot$일 광학산업 기술협력 세미나)를 연재한다. 9월호에는 광메모리 매체의 역할, 광디스크 드라이브 시스템의 구성, 위상변화 광오버라이트 메모리의 원리, 위상변화재료를 다뤘다. 이번 호에는 위상변화 광디스크의 구성재료, 위상변화 공디스크의 오버라이트 특성, 위상변화 광디스크와 광자기디스크의 비교, DVD를 실현하는 기술 등을 소개한다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.6 s.123
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• pp.477-483
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• 2007

Major noise source in high speed rotating optical disk drives (CD and DVD-ROM) arises due to the high-speed airflow produced from the upper and lower surfaces on the rotating disk. The present paper deals with the experimental approach how to identify the noise source based on the fundamental principles of aeroacoustics and to propose a reduction method of the noise source. The CD-ROM device is composed of disk, window tray, motors at the bottom place and electronic circuit plate also located below the window plate. The window is cut in the tray to read the disk information using the optical device located below the tray and moving linearly from the center of the disk through the end of the disk. All components are possible noise generators. Experimental studies were carried out in the anechoic room with various design modifications, such as tray geometry, window size and hole location on tray, to identify the major aerodynamic noise source and significant reductions of the aerodynamic noise were obtained.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.1009-1012
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• 1999

Recently, there is a strong need of DVD (Digital Versatile Disk) system of high density. high speed, and high accuracy System performances mostly depend on not only optical system, but also servo technology to drive it. Therefore, we investigate main technology concerned with optical pick-up unit based on 4.7GB DVD-RAM and analyzes technology of optical and servo systems that are required for high density high speed and high accuracy from the viewpoint of control. And then, we design a linear controller based on specification of 4.7GB DVD-RAM that is commercially available now. We analyze the dynamic characteristics of optical system that is coupled with control system and verify effect on performance indices of servo due to Parameter variation of pick-up by simulation. Finally, we will propose controller design specifications and provide direction of technical development for servo system and problems coupled with high capacity for 15GB level in the future.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.4
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• pp.270-276
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• 2003

The disturbance observer (DOB) has been widely utilized fer high precision and high speed motion control application. However, it still lacks the analysis for the robustness brought by using DOB. This paper summarizes six guidelines for the design of DOB taking into account the robustness and control performance in case of the second order system. For effectiveness of the proposed guideline, the actual implementation and experimental results of the DOB is compared in the Optical Disk Drive(ODD) servo system. In the DVD player and DVD-ROM drive, the guidelines of DOB are useful, and the disturbance rejection performance is improved under the DOB system.