• Journal of KSNVE
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• v.9 no.2
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• pp.324-330
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• 1999

With the increase of track density, high rotational speed and the compatibility for various media such as CD-ROM, CD-R/RW, DVD-ROM/RAM/RW etc. in optical disk drive, the effective anti-vibration design is so crucial for robust operaton. Especailly when the drive is self-excited by unbalanced disk, internal sled base vibration and its external transmission to the case bring about so severe problem. Generally these two consideration points the practical anti-vibration design process to control thses two conflictive properties using finite element analysis. As an example of the design process, Duro 25 and 40 visco-elastic rubber mount was selected and analyzed. The stiffness obtained from FEM rubber model was well matched with the experiments. Also it was confirmed that the internal and external vibration induced from unbalanced disk have good agreement with experimental results. The proposed design process is adopted to the slim-type optical disk drive.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.3
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• pp.1-12
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• 2013

Illegal software use have been abroad through online (internet) and offline (CD, DVD, USB, etc.). It infringes intellectual property rights and weakens the will to software development. Also, it generates the software errors and virus intrusion in PC. It hinders national software industry and induces the personal and national trade friction. Many group (company, office, organization, institution, etc.) have been realized the prohibition of illegal software use. But, it is too hard to monitor and control illegal software use. In this paper, we propose a method of software management in a group. A software module of client agency is installed in all PC of the group. A main server of the software management controls the all of the PC through the communication. The server blocks the install of illegal software, permits the install / use of honest goods software, monitors the license (term, amount) in all the PC. The system prevents errors of illegal software use, all cuts the virus intrude through the illegal software, improves the performance of PC relatively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.580-586
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• 2005

In this study, experimental tests for driving noise of various optical disk drives (ODD) have been performed using 1/2' microphone noise measurement system. Several new and old ODD models by different manufacturers are practically considered and compared far realistic driving conditions. Sound insulation case with absorbing material fur the present experimental tests is designed and constructed using CATIA system. It is found that average data transfer rate, operating RPM, and sound noise level seems to be different for the same opposed speed ODD by different manufacturers. Moreover, driving sound noise level can be largely affected by both tray shape and driving speed even for the same apparent data transfer rate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.144-149
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• 2006

최근 저소음형 fan 의 도입과 컴퓨터 케이스의 설계 변경 등으로 컴퓨터 소음이 저감되어, HDD 나 CD/DVD-ROM 등에서 발생하는 협대역 소음들이 문제가 되기도 한다. 특히 HDD 의 소음은 회전 속도의 증가와 휴대용 컴퓨터나 외장 HDD와 같이 사용자에 근접한 환경에서 사용되는 빈도가 높아짐에 따라 소음제어에 대한 관심이 증가되고 있다. 본 연구에서는 HDD 소음 분석 및 제어에 적합한 방법론 정립을 위한 음향/진동 분석이 수행되였다. 먼저 음압과 음향 파워, 진동속도를 측정하여 각 면의 기여도와 문제가 되는 주파수 대역을 선정하여 그 원인이 무엇인지를 실험적으로 찾아내고, 소음저감을 발안을 제시하였다. 이러한 개선 방안들은 실험적인 방법으로 검증되었으며, 음향 진동 분석을 통한 소음원 파악 및 적절한 개선 방향의 설정은 향후 HDD 설계시 유용한 정보로 활용될 수 있을 것이다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.117-124
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• 2007

In order to operate CD and DVD compatibly in a pickup system, the objective lens comprise diffractive optical element(DOE) zone and aspheric curvature on its lens surface. The DOE objective lens is effective to simplify this dual-purpose pickup system of the 655nm and 785nm wavelength by using only one lens, but requires more precision manufacturing process and system due to the complicated shape. This paper presents the overall manufacturing process of this objective lens and describes main parameters in each process, for the correction of the aspheric surface in its core, the shrinkage compensation after injection molding, and the uniformity compensation by adjusting molding conditions.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.582-587
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• 2002

Current information storage devices, such as HDD, CD/DVD-ROM/RW, probe-based memory and hologram memory, are compared with biological information storage mechanisms in DNA and brain memory. Newly developed approaches to overcome the limit of storage capacity are introduced in both magnetic and optical recording devices. Linear and areal density of information stored in the biological and mechanical storages are compared for the applications and developments of new storage devices.

• Journal of KSNVE
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• v.9 no.4
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• pp.693-702
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• 1999

We study the characteristics of airflow and sound noise induced by disk rotation in optical disk drives. The characteristics of airflow around a rotating disk surrounded by various tray structures are numerically investigated using a commercial CFD program and then compared with experimental results. Sound pressure and intensity caused by the fluid-structure interactions in the CD/DVD-ROM drive are measured, and the effect of the ariflow on the sound noise and disk vibration is discussed. In order to reduce airflow-induced noise and vibration around the rotating disk, tray geometry is modified. Both numerical and experimental studies implemented with different tray models show that the improved tray model alters the characteristics of the disk-induced airflow, causing the reduction of the airflow-induced sound level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.218-226
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• 1998

Recent trends and the effect of mechanical vibrations in optical disk drives are reviewed in this paper. The Nation from CD drives to high density DVD drives and the development of writable optical disk drives require tighter mechanical tolerance. The demand for faster access time and higher data transfer rate also leads to critical mechanical problems to limit the tracking and focusing servo performance. The current mechanical issues to limit the performance of the drives and various technologies to overcome the mechanical problems are introduced. Vibrations of disk-spindle system, actuator and suspension designs of the optical pick-up, and general mechanical designs for the fast and stable access mechanism are considered.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.360.1-360
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• 2002

Current information storage devices, such as HDD, CD/DVD-ROM/RW, probe-based memory and cabon nano tubes, are compared with biological information storage mechanisms in DNA and brain memory. Various biological components in living cells are analyzed based on "irreducible complexity" of intelligent design concept. Linear and arel density of information stored in the biological and mechanical storages are compared for the applications and developments of new storage devices.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1169-1176
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• 2005

In this study, experimental tests for driving noise of various optical disk drives (ODD) have been performed using 1/2' microphone noise measurement system. Several new and old ODD models by different manufacturers are practically considered and compared for realistic driving conditions. Sound insulation case with absorbing material for the present experimental tests is designed and constructed using CATIA system. It is found that average data transfer rate, operating RPM, and sound noise level seem to be different for the ODD models with same denoted speed by different manufacturers. Moreover, driving sound noise level can be largely affected by both tray shape and driving speed even for the condition of the same apparent data transfer rate.