• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1076-1079
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• 2005

Data storage related with writing and retrieving requires high storage capacity, fast transfer rate and less access time in. Today any data storage system can not satisfy these conditions, but holographic data storage system can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System architecture without mechanical actuating part is possible, so fast data transfer rate and high storage capacity about 1Tb/cm3 can be realized. In this paper, to correct errors of binary data stored in holographic digital data storage system, find cluster centers using clustering algorithm and reduce intensities of pixels around centers. We archive the procedure by two algorithms of C-mean and subtractive clustering, and compare the results of the two algorithms. By using proper clustering algorithm, the intensity profile of data page will be uniform and the better data storage system can be realized.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.83-87
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• 2005

Data storage related with writing and retrieving requires high storage capacity, fast transfer rate and less access time in. Today any data storage system can not satisfy these conditions, but holographic data storage system can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System architecture without mechanical actuating pare is possible, so fast data transfer rate and high storage capacity about 1Tb/cm3 can be realized. In this paper, to correct errors of binary data stored in holographic digital data storage system, find cluster centers using clustering algorithm and reduce intensities of pixels around centers. We archive the procedure by two algorithms of C-mean and subtractive clustering, and compare the results of the two algorithms. By using proper clustering algorithm, the intensity profile of data page will be uniform and the better data storage system can be realized.

• 한국광학회지
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• 제13권6호
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• pp.486-492
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• 2002

본 논문에서는 디지털 홀로그래픽 데이터 저장 시스템에서 2차원 데이터의 저장과 복원 동안에 발생되는 상호 픽셀에 의한 간섭(intersymbol interference:ISI)을 완화하고 bit-error-rate(BER) 성능개선을 위해 1차원 및 2차원 최소 평균-제곱-에러 (minimum mean-squared-error:MMSE) 등화(equalization)를 적용하였다. 홀로그래픽 저장 시스템으로부터 복원된 10개의 페이지에 대해서 등화 수행전보다 1차원 및 2차원 MMSE등화 적용 후, BER과 signal-to-noise ratio(SNR)이 향상됨을 보였다.

• 전자공학회논문지D
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• 제35D권2호
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• pp.101-109
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• 1998

In this paper, we implemented holographic optical memory systm which can store and reconstruct many images using new input and angular multiplexing method. In the new input method, phase infomation of input image is inputed in the recording material instead of brightness information. To do so, we represented the images, which captured with CCD camera or displayed on the computer monitor, on the liquid crystal television(LCTV) which removed polarizer/analyzer. Therefore, we can generate uniform input beam intensity regardless of the total brightness of input image, and apply the scheduled recording method. Also we can increase the intensity of input beam so reduce the recording time of input image. And reconstructedimage is acquired by transforming phase information into brightness information of image with analyzer. The incident angle of reference beam is acquired by Fourier transform of the binary phase hologram(BPH) which designed with SA algorithm on the LCTV. The proposed optical memory system is stable because the incident angle of the reference beam is controlled easy and electronically. We demonstreated optical experiment which store and reconstruct various type images in BaTiO$_{3}$ using proposed holographic memory system.

• 한국광학회:학술대회논문집
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• 한국광학회 2007년도 하계학술발표회 논문집
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• pp.229-230
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• 2007

Several encryption techniques were successfully applied to secure holographic memory systems.[1,2] In these systems the reference beam, object beam, or both can be encoded optically. Optics provides many degrees of freedom with which the optical beam may be encoded, such as amplitude, phase, wavelength, and polarization.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1260-1263
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• 2005

Data storage related with writing and retrieving requires high storage capacity, fast transfer rate and less access time. Today any data storage system cannot satisfy these conditions, however holographic data storage system can perform faster data transfer rate because it is a page oriented memory system using volume hologram in writing and retrieving data. System can be constructed without mechanical actuating part therefore fast data transfer rate and high storage capacity about 1Tb/cm3 can be realized. In this research, to reduce errors of binary data stored in holographic data storage system, a new method for bit error reduction is suggested. First, find fuzzy rule using experimental system for Element of Holographic Digital Data System. Second, make fuzzy rule table using Genetic algorithm. Third, reduce prior error element and recording Digital Data. Recording ratio and reconstruction ratio will be very good performance

• Journal of the Optical Society of Korea
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• 제6권4호
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• pp.172-179
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• 2002

Like the conventional digital storage systems, volume holographic memory can be deteriorated by burst errors due to its high-density storage characteristics. These burst errors are used byoptical defects such as scratches, dust particles, etc. and are two-dimensional in a data page. To deal with these errors, we introduce some concepts for describing them and propose efficient two- dimensional interleaving schemes. The schemes are two-dimensional lattices of an error-correction code word and have equilateral triangular and square structures. Using these structures, we can minimize the number of code words that are interleaved and improve the efficiency of the system. For large size burst errors, the efficient interleaving structure is an equilateral triangular lattice. However, for some small size burst errors, it is reduced to a square lattice.

• 한국광학회지
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• 제11권6호
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• pp.447-451
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• 2000

본 논문에서 통신채널과 고밀도 저장시스템에서 광범위하게 사용되는 적응 등화기를 디지털 홀로그래픽 광메모리 시스템의 저장과 복원 과정에서 발생되는 ISI를 완화시키고 bit-error-rate(BER)를 개선을 위해서 적용하였다. 실험결과 적응 등화기를 적용한 경우 BER 성능이 단순 임계값에 의한 이진판별과정보다 평균적으로 약 19.6% 향상됨을 보였다.

• 전자공학회논문지D
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• 제35D권9호
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• pp.70-76
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• 1998

본 논문에서는 LCB 공간광변조기의 화소를 전자적으로 제어함으로써 LCD에서 빛을 통과시키는 창을 만들고, 이러한 창을 전자적으로 상하 좌우로 이동시킴으로써 홀로그램을 고밀도로 각다중화할 수 있는 방법을 제시하였다. “10×10”의 화소를 창의 기본크기로 사용할 경우 1,536개의 어드레스를 만들 수 있고, “2×2”의 화소를 창의 기본크기로 사용하여 총 38,400개의 어드레스를 만들 수 있다. 본 논문에서 제안된 방법의 유효성을 입증하기 위해, 30개의 어드레스를 이용하여 영상을 기록하고 복원하였다.

• 조명전기설비학회논문지
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• 제18권3호
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• pp.15-19
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• 2004

다중모드 광섬유를 이용한 홀로그래픽 메모리 시스템을 제안하였다. 이 시스템에서 다중모드 광섬유에서 나온 빛을 기준빔으로 사용하여 홀로그램을 다중화 하였다. 제안된 시스템은 다중모드에서 나온 스펙클 패턴과 다중모드 광섬유의 위치와 같은 2가지의 다중화 자유도를 가지고 있다.