• 전자공학회지
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• 제23권7호
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• pp.37-43
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• 1996

DVD(Digital Versatile Disk)는 CD(Compact Disk)에 비해 약 9배의 저장용량(4.7GByte)을 갖는 디스크로 멀티미디어 시대를 위한 최적의 기록 매채로 그 중요성이 부각되고 있다. Player의 용도 또한 가전 영역인 audio/video system과 computer영역인 DVD-ROM모두에 적용될뿐만 아니라 기존의 모든 CD도 호환되도록 하고 있어 DVD판매 시장이 매우 크게 형성될 것으로 예측하고 있다. 여기에서는 DVD요소 기술과 동향 및 전망, 규격 내용, 그리고 DVD의 시장 동향에 관하여 기술하고자 한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.585-588
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• 2001

Particle contamination on the data storage disks has been a serious problem for magnetic hard disk drive manufacturers. For high storage optical disks, such as DVD-ROM/RAM or NFR (near field recording) system, particle-induced damages can be also detected because only a few micrometer particles can prevent read/write signal from optical lens. The increasing areal density and smaller bit size accelerates particle induced damages on the optical disk. One of the methods to prevent particle contamination on the optical disk surface is to handle the disk enclosed in a cartridge like a modern DVD-RAM disk. However, even for a perfectly sealed disk drive, particles are found inside the drive. The other method is to improve disk surface characteristics. Particle contamination on the surface can be reduced by proper selection of disk coating materials. [n this paper, particle detachment ratios for CD (compact disk), DVD (digital versatile disk), HD (magnetic hard disk), HD with Jut lubricant, and aluminosilicate substrate HD were investigated. Surface roughness and surface energy of the test disks were compared with the particle detachment ratios. Proper substrate and lubricant characteristics to reduce particle contamination on the disk surface were found.

• 한국광학회지
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• 제8권4호
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• pp.255-259
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• 1997

본 연구에서는, Nipkow 원판을 사용하는 공초점 현미겨을 구성하여 시료의 2차원 영상을 얻었으며, 이들을 간단한 알고리즘으로 연결하여 표면의 3차원 영상을 얻었다. 마이크로 필름으로 제작한 Nipkow 원판의 적절한 경로로 통과하는 빛의 투과율은 0.5% 정도였으며, 따라서 반사율이 높은 물체만을 관찰할 수 있었다. 광원으로는 파장 692.7 nm의 반도체 레이저를 사용하였다. 구성된 현미경으로 전산기용 기억소자 칩 표면에 식각된 회로의 깊이와 거칠기를 관찰할 수 있었따. 재생전용 compact disk(CD)도 표면의 보호막을 제거하였을 때 표면에 있는 pit들의 배열 구조가 관찰되었다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.470-473
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• 2003

Extensive studies have been conducted for reducing the residual stresses and birefringence in injection-molded optical disk substrate. Flow-induced and thermally-induced stresses and birefringence have been found as two main sources during injection molding process. However, high speed rotation also induces extra stresses and birefringence in real operation of disk drives. In the present paper rotation-induced in-plane birefringence has been measured and presented for CD and DVD substrates at different radial position. About 10 - 15 nm of extra retardation has been measured up to 4,800 rpm.

• 천문학논총
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• 제14권1호
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• pp.1-8
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• 1999

We performed VRI CCD surface photometry of three spiral galaxies of HCG10 in order to understand the effect of interactions in the compact group. The morphology of the largest member NGC 536 seems to be normal but its bulge is thought to be of an oblate spheroid. The central surface brightness of the disk of NGC 536 is much fainter than that of disks of nearby spiral galaxies. The morphologies of NGC 531 and NGG 542 appear to be affected by interactions which lead to a warped disk in NGC 531 and a slightly bent disk in NGC 542. NGC 531 have a boxy bulge and a Freeman Type II disk both of which strongly suggest the presence of a bar in the galaxy. There is a break in the slope of the luminosity profile of NGC 542 which is dominated by the disk component.

• 조명전기설비학회논문지
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• 제22권3호
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• pp.34-39
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• 2008

The purpose of this paper is characteristic analysis of multi-disk axial-gap pm motor for turbo compressor. The axial-gap permanent magnet motor has shown a growing interest in high-speed application for its high-efficiency, compact size and low vibration characteristics due to core-less structure. To achieve high-power, the axial-gap PM motor has multi-disk structure of stator and rotor disk. Because of its complicated magnetic flux path, it is not easy to calculate a dynamic characteristics using finite element analysis. In this paper, the simplified 2-D unfolded model to predict EMF characteristic is presented. To verify thesuggested 2-D unfolded model analysis of back-EMF characteristic was calculated and compared 3-D finite element. Finally the proposed method is verified by experimental results and shows good agreement with test results.

• 도시과학
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• 제10권1호
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• pp.11-20
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• 2021

In this study, the vibration characteristics were theoretically analyzed by modeling a free isotropic rotating disk with an outer periphery with a fixed inner periphery, paying attention to disks used as storage devices for information devices, especially magnetic disks, magneto-optical disks, and compact disks in which the head and disk are non-contact. Iluminate with Composite materials represented by fiber-reinforced plastics (FRP) have high specific strength (strength/density) and specific stiffness (narrowness/density). It is used in the elements, and its use is rapidly expanding. Under this circumstance, the disk currently manufactured using an isotropic material made of various plastic materials such as aluminum or polycarbonate as a base material is an extremely anisotropic material made of a composite material, and the circumferential stiffness of the disk is made of reinforcing fibers in the circumferential direction. It is modeled as an anisotropic rotating disk with increased, and its influence on the vibration characteristics is revealed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.589-595
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• 2001

The present study conducted heat transfer analysis in multi-layer of CD-R. It is necessary to analyze heat transfer during the recording process to find optimum power and write strategy in CD-R. This study investigated effects of several parameters such as recording speed, laser power, layer thickness and thermal property. The calculated results presented temperature distribution in the multi-layer and detailed information of recording characteristics. Optimum laser power was estimated, comparing an optimum mark length with the calculated mark lengths. The results showed that the optimum laser power was influenced significantly by the layer thickness and the thermal properties of the dye.

• 천문학논총
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• 제30권2호
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• pp.513-515
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• 2015

We investigate $H\small{I}$ data for a pair of blue compact dwarf galaxies (BCDs), ESO 435-IG20 and ESO 435-IG16, obtained with the Australia Telescope Compact Array. The outer $H\small{I}$ disk is highly disturbed and asymmetric in both galaxies showing a gas tail and/or a broad/extended gas disk on only one side. Based on their low-density surroundings and small projected distance (<80 kpc) at a similar redshift, we conclude that tidal interaction between these two BCDs is responsible for the morphological and kinematical peculiarities in $H\small{I}$. We also investigate their star formation rates using $H{\alpha}$ and UV imaging data to probe their interaction history.

• 한국소음진동공학회논문집
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• 제19권1호
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• pp.76-84
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• 2009

The vibration and stability of thin, flexible corotating disks in an enclosed compressible fluid is investigated analytically and compared with the results of a single rotating disk. The discretized dynamical system of the corotating disks is derived in the compact form of a classical gyroscopic system similar with a single disk. For the undamped system, coupled structure-acoustic traveling waves destabilize through mode coalescence leading to flutter instability. However, it is found that the flutter regions of the corotating disks are wider than those of a single disk. A detailed investigation of the effects of dissipation arising from acoustic or disk damping is also performed. Finally, in the presence of both acoustic and disk dampings, the instability regions are found and compared with those of a single disk. Although this study does not allow a radial clearance between the disk and the enclosure, the computational frame work of the problem can be expanded to the system having the radial clearance in an enclosure.