• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.124-127
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• 2005

Rewritable optical memory devices such as an CD-RW and DVD+RW are data storage media, which take advantage of the different optical properties in the amorphous and crystalline states of phase change materials. The switching property, structural transformation, transformation kinetics and chemical bindings of $Ge_xSb_{100-x}$($6{\le}x{\le}$34) were studied to investigate the feasibility of applying $Ge_xSb_{100-x}$ alloys in optical memory. The $Ge_xSb_{100-x}$ thin film was deposited by RF magnetron co-sputtering system and phase change characteristics were investigated by X-ray diffraction (XRD), static tester, inductively coupled plasma atomic emission spectrometer (ICP-AES) and atomic force microscopy (AEM). Optimum fiim composition of $Ge_xSb_{100-x}$ was studied and its minimum time fur laser induced crystallization and optical contrast fur phase transition was performed. These results might be correlated with the binding energies between Ge and Sb, and indicate that $Ge_xSb_{100-x}$ have an potential far optical memory applications.

• 정보저장시스템학회논문집
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• 제6권2호
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• pp.63-67
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• 2010

Holographic data storage system is one of next generation high density optical memories. Thereby storing multiple data pages using multiplexing method in one spot, we can achieve high store density and fast access time. However, for uniform writing, we must control exposure time properly by the change of writing material characteristics. Many studies have been investigated about exposure time scheduling. However, once it is decided, we cannot change the scheduled time. Therefore, it is hard to obtain uniform data intensity. In this study, we propose exposure time control method using additional red beam as the monitoring signal. Through reconstructed red beam intensity in real time, we can adjust exposure time by the writing condition change. We construct compensation method mathematically and verify the feasibility of proposed method through the experiments.

• 정보저장시스템학회논문집
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• 제1권1호
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• pp.1-22
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• 2005

There are two important trends in the modern information society, including digital networking and ubiquitous environment. Thus it is strongly required to develop new information storage devices such as high density storages to match the increased data capacity and small size storage devices to be applied to the mobile multimedia electronics. So far, many approaches have been studied for the high density memory, including the holographic memory, super-RENS and near-field recording using solid immersion lens (SIL) or nano-probe for the ODD (Optical Disk Drive) system, and the perpendicular magnetic recording and heat-assisted magnetic recording for the HDD (Hard Disk Drive) system. In addition, new mobile storage devices have been prepared using 0.85" HDD and 30mm ODD systems from a lot of foreign and domestic companies and institutes. In this paper, the recent technology trend for the next generation information storage system is summarized to offer a research motivation and encouragement to new researchers in this field with an emphasis on the technical issues of the increase of data capacity and decrease of device size.

• 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.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.56-57
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• 2000

In this paper, DFE with feedforward section(FDFE) is used to mitigate ISI and improve BER generated in the course of storage and retrieval of high-density 2-dimensional data in digital holographic memory system. From the result of experiment, BER performance of DFE with feedforward section is improved about 37% than binary-decision course by direct thresholding.

• 한국통신학회논문지
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• 제31권11C호
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• pp.1052-1057
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• 2006

본 논문에서는 고밀도 광기록 장치에서 발생하는 디스크 기울임 현상으로 인한 검출 성능 저하를 방지하기 위해서 디스크 기울임 분석기를 갖는 적응 등화 PRML 검출 방법을 VerilogHDL을 이용하여 구현하였다. 디스크 기울임의 분석을 위하여 고정된 패턴으로 일정한 간격마다 반복되는 동기 데이터를 이용하여 분석된 디스크의 기울임 정도를 측정하여 ROM에 저장된 등화기 계수값과 가지 메트릭의 기준값을 갱신한다. 이러한 방법은 지속적으로 계수값을 계산하여 갱신시켜줘야 하는 기존의 적응등화 방법에 비해 간단하게 각각의 계수값을 갱신시킬 수 있다. Hynix $0.35{\mu}m$ STD cell library로 회로를 합성한 결과 35K 정도의 게이트를 필요로 하고 최대동작속도 140MHz의 성능을 보였다.

• 한국통신학회논문지
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• 제31권10C호
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• pp.927-932
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• 2006

본 논문은 고밀도 광 기록 저장장치에서 오류의 주 원인이 되는 tangential tilt의 문제를 해결하기 위한 개선된 부분응답최대유사도 신호 검출 방법을 제안한다. 틸트의 변화에 따라 등화기 계수와 비터비 디코더의 가지 기준값을 적응적으로 갱신하여 채널의 변화에 잘 적응하도록 하였다. 채널의 변화를 감지하는 요소로 주기적으로 반복되는 데이터의 동기패턴을 이용하여 누적 평균을 취한 후 변화량에 해당되는 등화기 계수값과 비터비 디코더의 가지 기준값을 동시에 갱신한다. 제안된 방법을 적용한 결과 기존의 PRML 검출기에 비해 비트 오류율 10-6에서 최대 4dB이상 성능이 향상되는 것을 확인할 수 있었다.

• E2M - 전기 전자와 첨단 소재
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• 제8권2호
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• pp.229-236
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• 1995

Multimedia has created a system environment that needs a combination of diverse peripherals, faster I/O, and easier configuration. The sheer volume of data one can expect with multimedia hardware and applications storage systems of higher capacity and faster data transfer rate. Unlike the magneto-optical(MO)disk technology which uses bias magnetic field in writing, both the reading and the writing in the phase change (PC) technology are performed only by laser light. In PC optical media, an active layer is reversibly converted between amorphous state and crystalline state by changing irradiation conditions of focused laser beam. Thus, as compared with MO disk, the PC disk has such great advantages that signals can be reproduced by change of reflectance of laser beams in the same manner as the compact disc. The reflectivity of a phase-change spot can be altered in a single pass under the head only through modulation of laser power. The principles and the current status of phase-change optical recording media combined with possible applications are discussed in the present article.

• 마이크로전자및패키징학회지
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• 제7권4호
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• pp.37-42
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• 2000

고성능과 고속화의 면에서 광저장장치의 관심은 상당히 높다. 그러나 하드디스크와 비교하여 광저장장치는 임의의 데이터에 대한 탐색속도가 매우 늦다. 따라서, 광저장장치에서의 새로운 형태의 연구가 필요하다. 본 연구는 하드디스크 장치와 유사한 스윔 암 구동기를 사용한 광저장장치의 공기베어링의 특성에 관해 연구하였다. 광저장장치에서 요구되어지는 최적의 슬라이더 형상을 구하기 위하여 공기 베어링면의 형상변화에 따른 부상상태에 관한 민감도를 연구하였다.

• 정보저장시스템학회논문집
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• 제2권1호
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• pp.43-49
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• 2006

Fractal/angle multiplexing is a $LiNBO_3$ crystal using a X-Y Galvano mirror, and the random access concept in fractal/angle multiplexing are discussed in this paper. First, the brief introduction of the designed holographic digital data storage system is presented. Then, the average access time concept for the storage system is newly defined, and the comparison of the average access time between the holographic storage and a conventional optical disk is performed. Second, the basic simulation and experiment to find the X-Y Galvano mirror dynamics are conducted. From this analysis, we find that the average access time in our HDDS which has 6 degree scan angle is about 5 msec. This result is very high performance when it compared with the average access time of a conventional optical disk. Finally, some recording results using fractal/angle multiplexing are presented, then, the relationship between bit error rate and angle mismatch for the each multiplexing are discussed.