• Title, Summary, Keyword: Phase encoding

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Optical Encryption System using a Computer Generated Hologram

  • Kim, Jong-Yun;Park, Se-Joon;Kim, Soo-Joong;Doh, Yang-Hoi;Kim, Cheol-Su
    • Journal of the Optical Society of Korea
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    • v.4 no.1
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    • pp.19-22
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    • 2000
  • A new image encoding and identification scheme is proposed for security verification by us-ing a CGH(computer generated hologram), random phase mask, and a correlation technique. The encrypted image, which is attached to the security product, is made by multiplying a QP- CGH(quadratic phase CGI) with a random phase function. The random phase function plays a key role when the encrypted image is decrypted. The encrypted image can be optically recovered by a 2-f imaging system and automatically verified for personal identification by a 4-f correlation system. Simulation results show the proposed method can be used for both the reconstruction of an original image and the recognition of an encrypted image.

10 GHz Multiuser Optical CDMA Based on Spectral Phase Coding of Short Pulses

  • Ruan, Wan-Yong;Won, In-Jae;Park, Jae-Hyun;Seo, Dong-Sun
    • Journal of IKEEE
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    • v.13 no.1
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    • pp.65-70
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    • 2009
  • We propose an ultrashort pulse optical code-division multiple-access (O-CDMA) scheme based on a pseudorandom binary M-sequence spectral phase encoding and decoding of coherent mode-locked laser pulses and perform a numerical simulation to analyze its feasibility. We demonstrate the ability to properly decode any of the multiple (eight) 10 Gbit/s users by the matched code selection of the spectral phase decoder. The peak power signal to noise ratio of properly and improperly decoded $8{\times}10 Gb/s$ signals could be greater than 15 for 127 M-sequence coding.

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Intra-Motion Compensation Using CSRS method in MRI

  • Ro, Y.M.;Yi, J.H.;Cho, Z.H.
    • Journal of Biomedical Engineering Research
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    • v.15 no.4
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    • pp.377-382
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    • 1994
  • In the conventional Fourier imaging method in MRI (Magnetic Resonance Imaging), intramotion such as pulsatile flow makes zipper-like artifact along the phase encoding direction. On the other hand, line-integral projection reconstruction (LPR) method has advantages such as imaging of short T2, object and reduction of the flow artifact by elimination of the flow-induced phase fluctuation. The LPR, however, necessarily requires time consuming filtering and back-projection processes, so that the reconstruction takes long time. To overcome the long reconstruction time of the LPR and to obtain the flow artifact reduction effect, we adopted phase corrected concentric square raster sampling (CSRS) method and improved its imaging performance. The CSRS is a fast reconstruction method which has the same properties with the LPR. In this paper, we proposed a new method of flow artifact reduction using the CSRS method. Through computer simulations and experiments, we verified that the proposed method can eliminate phase fluctuations, thereby reducing the flow artifact and re- markably shorten the reconstruction time which required long time in the LPR.

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Image Authentication Using Only Partial Phase Information from a Double-Random-Phase-Encrypted Image in the Fresnel Domain

  • Zheng, Jiecai;Li, Xueqing
    • Journal of the Optical Society of Korea
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    • v.19 no.3
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    • pp.241-247
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    • 2015
  • The double-random phase encryption (DRPE) algorithm is a robust technique for image encryption, due to its high speed and encoding a primary image to stationary white noise. Recently it was reported that DRPE in the Fresnel domain can achieve a better avalanche effect than that in Fourier domain, which means DRPE in the Fresnel domain is much safer, to some extent. Consequently, a method based on DRPE in the Fresnel domain would be a good choice. In this paper we present an image-authentication method which uses only partial phase information from a double-random-phase-encrypted image in the Fresnel domain. In this method, only part of the phase information of an image encrypted with DRPE in the Fresnel domain needs to be kept, while other information like amplitude values can be eliminated. Then, with the correct phase keys (we do not consider wavelength and distance as keys here) and a nonlinear correlation algorithm, the encrypted image can be authenticated. Experimental results demonstrate that the encrypted images can be successfully authenticated with this partial phase plus nonlinear correlation technique.

PID Control Design with Exhaustive Dynamic Encoding Algorithm for Searches (eDEAS)

  • Kim, Jong-Wook;Kim, Sang-Woo
    • International Journal of Control, Automation, and Systems
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    • v.5 no.6
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    • pp.691-700
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    • 2007
  • This paper proposes a simple but effective design method of PID control using a numerical optimization method. In order to achieve both stability and performance, gain and phase margins and performance indices of step response directly compose of the cost function. Hence, the proposed approach is a multiobjective optimization problem. The main effectiveness of this approach results from the strong capability of the used optimization method. A one-dimensional example concerning gain margin illustrates the practical applicability of the optimization method. The present approach has many degrees of freedom in controller design by only adjusting related weight constants. The attained PID controller is compared with Wang#s and Ho#s methods, IAE, and ISE for a high-order process, and the simulation result for various design targets shows that the proposed approach achieves desired time-domain performance with a guarantee of frequency-domain stability.

Cloning and Expression of a bpr Gene Encoding Bacillopeptidase F from Bacillus amyloliquefaciens CH86-1

  • Kwon, Gun-Hee;Park, Jae-Yong;Kim, Jong-Sang;Lim, Jin-Kyu;Park, Cheon-Seok;Kwon, Dae-Young;Kim, Jeong-Hwan
    • Journal of Microbiology and Biotechnology
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    • v.21 no.5
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    • pp.515-518
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    • 2011
  • A gene encoding bacillopeptidase F, bpr86-1, was cloned from B. amyloliquefaciens CH86-1 isolated from cheonggukjang. This gene could encode a preproenzyme of 1,431 amino acids. When bpr86-1 was introduced into B. subtilis WB600 via pHY300PLK, an E. coli-Bacillus shuttle vector, the transformant showed fibrinolytic activity. During growth on LB, the fibrinolytic activity of cells increased sharply when they entered the stationary phase. The highest activity (761.4 mU/mg protein) was observed at 96 h of cultivation.

Could Decimal-binary Vector be a Representative of DNA Sequence for Classification?

  • Sanjaya, Prima;Kang, Dae-Ki
    • International journal of advanced smart convergence
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    • v.5 no.3
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    • pp.8-15
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    • 2016
  • In recent years, one of deep learning models called Deep Belief Network (DBN) which formed by stacking restricted Boltzman machine in a greedy fashion has beed widely used for classification and recognition. With an ability to extracting features of high-level abstraction and deal with higher dimensional data structure, this model has ouperformed outstanding result on image and speech recognition. In this research, we assess the applicability of deep learning in dna classification level. Since the training phase of DBN is costly expensive, specially if deals with DNA sequence with thousand of variables, we introduce a new encoding method, using decimal-binary vector to represent the sequence as input to the model, thereafter compare with one-hot-vector encoding in two datasets. We evaluated our proposed model with different contrastive algorithms which achieved significant improvement for the training speed with comparable classification result. This result has shown a potential of using decimal-binary vector on DBN for DNA sequence to solve other sequence problem in bioinformatics.

Reconstruction of Magnetic Resonance Phase Images using the Compressed Sensing Technique (압축 센싱 기법을 이용한 MRI 위상 영상의 재구성)

  • Lee, J.E.;Cho, M.H.;Lee, S.Y.
    • Journal of Biomedical Engineering Research
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    • v.31 no.6
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    • pp.464-471
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    • 2010
  • Compressed sensing can be used to reduce scan time or to enhance spatial resolution in MRI. It is now recognized that compressed sensing works well in reconstructing magnitude images if the sampling mask and the sparsifying transform are well chosen. Phase images also play important roles in MRI particularly in chemical shift imaging and magnetic resonance electrical impedance tomography (MREIT). We reconstruct MRI phase images using the compressed sensing technique. Through computer simulation and real MRI experiments, we reconstructed phase images using the compressed sensing technique and we compared them with the ones reconstructed by conventional Fourier reconstruction technique. As compared to conventional Fourier reconstruction with the same number of phase encoding steps, compressed sensing shows better performance in terms of mean squared phase error and edge preservation. We expect compressed sensing can be used to reduce the scan time or to enhance spatial resolution of MREIT.

Optical Image Encryption Technique Based on Hybrid-pattern Phase Keys

  • Sun, Wenqing;Wang, Lei;Wang, Jun;Li, Hua;Wu, Quanying
    • Current Optics and Photonics
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    • v.2 no.6
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    • pp.540-546
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    • 2018
  • We propose an implementation scheme for an optical encryption system with hybrid-pattern random keys. In the encryption process, a pair of random phase keys composed of a white-noise phase key and a structured phase key are positioned in the input plane and Fourier-spectrum plane respectively. The output image is recoverable by digital reconstruction, using the conjugate of the encryption key in the Fourier-spectrum plane. We discuss the system encryption performance when different combinations of phase-key pairs are used. To measure the effectiveness of the proposed method, we calculate the statistical indicators between original and encrypted images. The results are compared to those generated from a classical double random phase encoding. Computer simulations are presented to show the validity of the method.