• 디지털콘텐츠
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• 11호통권114호
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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.

• 소음진동
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• 제11권3호
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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.

• 월간포장계
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• 통권170호
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• pp.88-91
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• 2007

• 한국컴퓨터산업학회논문지
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• 제3권3호
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• pp.391-406
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• 2002

최근 관심을 끌고 있는 VOD 시스템을 현실적으로 실현 가능하게 하기 위해서는 대용량 멀티미디어 정보를 장기적으로 저장할 수 있도록 저가이면서 저장 용량이 큰 3차 저장장치를 사용하는 계층적 VOD 서버를 필요로 한다. 본 논문은 이러한 계층적 VOD 서버를 저가의 대용량 DVD 쥬크박스를 온라인 저장장치로 사용하여 구성하고, 여러 개의 스트림들을 적당한 시간을 주기로 드라이브들을 교대로 활용하게 함으로써 서비스 스트림을 최대화함으로써 효율을 높일 수 있다. 그러나 DVD 쥬크박스 내에서 하나의 스트림이 저장된 DVD-ROM의 교환은 상대적으로 긴 시간을 요구하므로 본 논문에서는 DVD 쥬크박스를 기반으로 한 VOD 서버에서 DVD-ROM의 교환시간을 은폐하면서 효율적인 데이터 전송을 지원 할 수 있는 파이프라인 로딩 기법을 제안한다. 또한 디스크를 캐쉬로 사용하여 스트림의 초기 일부분을 미리 디스크 캐쉬에 적재하여 놓음으로써 최대허용 스트림 수를 증가시킬 수 있는 기법을 제안한다. 제안된 기법들은 시뮬레이션 성능분석을 통하여 파이프라인 상황하에서 사용하는 드라이브 수에 비하여 최대 허용 스트림 수가 크게 증가될 수 있음을 보인다.

• 소음진동
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• 제11권1호
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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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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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.

• 광학세계
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• 제11권6호통권64호
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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.

• 한국소음진동공학회논문집
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• 제17권6호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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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.

• 제어로봇시스템학회논문지
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• 제9권4호
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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.