• 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.

• 벤딩인더스트리
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• 제7권3호통권21호
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• pp.48-50
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• 2007

중소기업에 근무하는 김모씨. 그는 영화라면 자다가도 벌떡 일어나는 영화광이다. 집에 홈씨어터 시설까지 구축하고 일주일에 평균 2~3편의 영화를 본다. 그는 주로 아파트 단지 앞 상가 내 비디오DVD 대여점에서 대여를 하는 편이다. 그런데 최근 이 대여점이 경영난으로 폐업을 해버려 영화 빌릴 곳이 없어 졌다. '이제 옆 동네까지 가서 DVD를 빌려 봐야 하는 가?' 난감해 하던 김모씨. 어느 날 회사 근처 편의점을 들어갔더니 요상하게 생긴 'DVD타워'라는 기계가 있는 게 아닌가. 김모씨는 이 제품이 DVD를 무인 대여하는 자판기라는 것을 알고 눈이 휘둥그레졌다. 최신 영화 등 다양한 타이틀을 제공하고 이용방법도 쉽고 편리하다. 그날 당장 요즘 인기를 끄는 최신 영화 2편을 대여하고 '휘파람'을 불며 편의점을 나섰다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.502-507
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• 2000

This paper presents 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. 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, resulting in a different pattern compared with those in the near field.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1095-1100
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• 2003

Experimental studies on the aerodynamic coupling effect on natural frequencies, critical speed and flutter instability of DVD disks are investigated in this paper. The experimental results are compared with the theoretical analyses where the aerodynamic effects are represented in terms of elastic, lift and damping and stiffness components. The experiments are performed using a vacuum chamber and DVD disks rotating in vacuum, open and enclosure with several different gaps between disk and wall. The following three results are given. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency decreases as the disk-wall gap is decreased. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.998-1003
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• 2003

The aerodynamically excited vibration and natural frequency of rotating CD and DVD disks are analytically and experimentally studied in this paper The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and damping components. The explicit expression on natural frequency of the air coupled disk is obtained as functions of the three aerodynamic coefficients. The experiments performed using a vacuum chamber and CD/DVD disks rotating in vacuum, open air and enclosure give three main results. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency of disks rotating in open air is larger than that in enclosure. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• 한국통신학회논문지
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• 제30권4C호
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• pp.247-252
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• 2005

현재 DVD 시스템의 채널에서 디코더는 16비트 입력을 받아 8비트 데이터 심볼을 복원한다. 이러한 DVD용 변조 코드는 주 테이블(main table)과 부 테이블(sub table)로 이루어진 EFMplus 코드를 사용한다. 본 논문에서는 디코더 구현시 필요한 코드 테이블의 크기를 줄이기 위해 EFMplus 코드를 3개의 그룹으로 나눈 후 각 코드의 가지 수를 줄이는 방법을 제안하고 이 코드 테이블을 이용하여 디코더를 구현하였다. 이 방식은 기존의 테이블을 이용하여 디코딩할 때 필요한 코드 수 1376개를 750개로 약 $46\%$정도 감소시켜 EFMplus 코드를 구현할 때 필요한 ROM의 크기를 약 2배 정도 줄였다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2005년도 춘계 종합학술대회 논문집
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• pp.165-171
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• 2005

MPEG II 비디오 스트림과 오디오 AC-3 스트림, 자막 스트림에 지역 코드, 복제 방지 메뉴 등을 프로그램 하여 하나의 스트림으로 만들고, 시나리오에 따라 속성, 명령 및 작동을 부여하여 최종 디스크 이미지(DVD)를 만드는 과정을 오소링(Authoring)이라고 한다. 이러한 오소링 (Authoring) 툴들은 다양하게 출시되어 있는데, 간단한 타이틀을 만드는 보급형부터 전문적인 영화 타이틀을 만드는 고급형까지 용도에 따라 선택하여 쓸 수 있다. 본 논문에서는 일반적인 IEEE 1394포트를 이용하여 영상과 음향을 컴퓨터로 캡처(Capture)해서 DVD를 만드는 오소링(Authoring) 과정을 일반인들이 Desktop PC로써 가장 많이 사용하고 있는 Window체계의 PC와 OSX 체계의 Macintosh를 중심으로 비교, 분석하고자 한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1231-1236
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• 2004

In the present work, the practical thermal design process of 1 DIN car DVD receiver described. In the course of its efficient design, CAE technique was essentially used. CAE technique has reduced research period, man power and material cost but has increased research convenience, organized results and persuasive power. CAE technique helped to study parameters such as vent, fan and heat sink. Using these elements, it tried to meet optimal thermal solution. But safety standard, printed circuit board and framework mechanism should be considered as the constraint. To overcome these constraints, we tried to communicate and compromise with projectors in charge. After all, the price of those efforts has made the most competitive heat sink for heat dissipation in the 1 DIN car DVD receiver market. Moreover, we are trying to save $3 per product by removing fan. This paper is supposed to show an example of the CAE technique and help thermal designers to make electronic packaging goods.

• 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.

• 월간포장계
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• 통권170호
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• pp.88-91
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• 2007