• Title, Summary, Keyword: Phase encoding

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Two-Dimensional Hybrid Codes using Identity Matrix and Symmetric Balance Incomplete Block Design Codes for Optical CDMA (광 코드분할다중접속을 위한 단위행렬과 Symmetric Balance Incomplete Block Design 부호를 사용한 2차원 하이브리드 부호)

  • Jhee, Yoon Kyoo
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.4
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    • pp.27-32
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    • 2014
  • Two-dimensional hybrid codewords are generated by using each row of identity matrix for spatial encoding and nonideal symmetric balance incomplete block design(BIBD) code for spectral encoding. This spatial/spectral optical code-division multiple-access (OCDMA) network uses single-balanced detectors to abstract the desired information bits and to eliminate the multiple-access interference(MAI). Analytical results show that the number of simultaneous users increases significantly by using the proposed hybrid codes.

Phase Mode Decision Scheme for Fast Encoding in H.264 SVC (H.264/AVC 스케일러블 비디오 코딩에서 빠른 부호화를 위한 단계적 모드 선택 기법)

  • Goh, Gyeong-Eun;Kang, Jin-Mi;Cho, Mi-Sook;Chung, Ki-Dong
    • Journal of KIISE:Computing Practices and Letters
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    • v.14 no.8
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    • pp.793-797
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    • 2008
  • To achieve flexible visual contents adaptation for multimedia communications, the ISO/IEC MPEG & ITU-T VCEG form the JVT to develop an SVC amendment for the H.264/AVC standard. JVT uses inter-layer prediction that can improve the rate-distortion efficiency of the enhancement layer. But inter-layer prediction causes computational complexity to be increased. In this paper, we propose a fast mode decision for inter frame coding. It makes use of the correlation between optimized prediction mode and its RD cost. Experimental results show that the proposed schemes save up to 38% of encoding time with a negligible coding loss and bit-rate increase.

Wire Optimization and Delay Reduction for High-Performance on-Chip Interconnection in GALS Systems

  • Oh, Myeong-Hoon;Kim, Young Woo;Kim, Hag Young;Kim, Young-Kyun;Kim, Jin-Sung
    • ETRI Journal
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    • v.39 no.4
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    • pp.582-591
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    • 2017
  • To address the wire complexity problem in large-scale globally asynchronous, locally synchronous systems, a current-mode ternary encoding scheme was devised for a two-phase asynchronous protocol. However, for data transmission through a very long wire, few studies have been conducted on reducing the long propagation delay in current-mode circuits. Hence, this paper proposes a current steering logic (CSL) that is able to minimize the long delay for the devised current-mode ternary encoding scheme. The CSL creates pulse signals that charge or discharge the output signal in advance for a short period of time, and as a result, helps prevent a slack in the current signals. The encoder and decoder circuits employing the CSL are implemented using $0.25-{\mu}m$ CMOS technology. The results of an HSPICE simulation show that the normal and optimal mode operations of the CSL achieve a delay reduction of 11.8% and 28.1%, respectively, when compared to the original scheme for a 10-mm wire. They also reduce the power-delay product by 9.6% and 22.5%, respectively, at a data rate of 100 Mb/s for the same wire length.

Cancellation of Motion Artifact in MRI (MRI에 있어서 체동 아티팩트의 제거)

  • Kim, Eung-Kyeu
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.37 no.3
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    • pp.70-78
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    • 2000
  • In this study, a new method for canceling MRI artifacts through the motion translation of image plane is presented Breathing often makes problems in a clinical diagnosis. Assuming that the head moves up and down due to breathing, rigid translational motions in only y(phase encoding axis) direction are treated Unlike the conventional Iterative phase retrieval algorithm, this method is based on the MRI imaging process and analyzing of Image property A new constraint condition with which the motion component and the true image component in the MRI signal can be separated by a simple algebraic operation is extracted After the x(read out) directional Fourier transformation of MRI signal is done, the y(phase encoding) directional spectrum phasing value is Just an algebraic sum of the Image component and the motion component Meanwhile, as It is known that the density of subcutaneous fat area is almost uniform in the head tomographs, the density distribution along a y directional line on this fat area is regarded as symmetric shape If the density function is symmetric, then the phase of spectrum changes linearly with the position Hence, the departure component from the linear function can be separated as the motion component Based on this constrant condition, the new method of artifact cancellation is presented Finally, the effectiveness of this algorithm IS shown by using a phantom with simulated motions.

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Cancellation of MRI Motion Artifact in Image Plane

  • Kim Eung-Kyeu
    • Journal of the Institute of Convergence Signal Processing
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    • v.1 no.1
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    • pp.49-57
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    • 2000
  • In this study, a new algorithm for canceling a MRI artifact due to the translational motion In the image plane is described. Unlike the conventional iterative phase retrieval algorithm, in which there is no guarantee for the convergence, a direct method for estimating the motion is presented. In previous approaches, the motions in the x(read out) direction and the y(phase encoding) direction were estimated simultaneously. However, the feature of x and y directional motions are different from each other. By analyzing their features, each x and y directional motion is canceled by the different algorithms in two steps. First, it is noticed that the x directional motion corresponds to a shift of the x directional spectrum of the MRI signal, and the non-zero area of the spectrum just corresponds to the projected area of the density function on the x axis. So the motion is estimated by tracing the edges between non-zero area and zero area of the spectrum, and the x directional motion is canceled by shifting the spectrum in an reverse direction. Next, the y directional motion is canceled by using a new constraint condition, with which the motion component and the true image component can be separated. This algorithm is shown to be effective by using a phantom image with simulated motion.

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Hybrid Color and Grayscale Images Encryption Scheme Based on Quaternion Hartley Transform and Logistic Map in Gyrator Domain

  • Li, Jianzhong
    • Journal of the Optical Society of Korea
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    • v.20 no.1
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    • pp.42-54
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    • 2016
  • A hybrid color and grayscale images encryption scheme based on the quaternion Hartley transform (QHT), the two-dimensional (2D) logistic map, the double random phase encoding (DRPE) in gyrator transform (GT) domain and the three-step phase-shifting interferometry (PSI) is presented. First, we propose a new color image processing tool termed as the quaternion Hartley transform, and we develop an efficient method to calculate the QHT of a quaternion matrix. In the presented encryption scheme, the original color and grayscale images are represented by quaternion algebra and processed holistically in a vector manner using QHT. To enhance the security level, a 2D logistic map-based scrambling technique is designed to permute the complex amplitude, which is formed by the components of the QHT-transformed original images. Subsequently, the scrambled data is encoded by the GT-based DRPE system. For the convenience of storage and transmission, the resulting encrypted signal is recorded as the real-valued interferograms using three-step PSI. The parameters of the scrambling method, the GT orders and the two random phase masks form the keys for decryption of the secret images. Simulation results demonstrate that the proposed scheme has high security level and certain robustness against data loss, noise disturbance and some attacks such as chosen plaintext attack.

GA-based Two Phase Method for a Highly Reliable Network Design (높은 신뢰도의 네트워크 설계를 위한 GA 기반 두 단계 방법)

  • Jo, Jung-Bok
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.9 no.5
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    • pp.1149-1160
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    • 2005
  • Generally, the network topology design problem, which is difficult to solve with the classical method because it has exponentially increasing complexity with the augmented network size, is characterized as a kind of NP-hard combinatorial optimization problem. The problem of this research is to design the highly reliable network topology considering the connection cost and all-terminal network reliability, which can be defined as the probability that every pair of nodes can communicate with each other. In order to solve the highly reliable network topology design problem minimizing the construction cost subject to network reliability, we proposes an efficient two phase approach to design reliable network topology, i.e., the first phase employs, a genetic algorithm (GA) which uses $Pr\ddot{u}fer$ number for encoding method and backtracking Algorithm for network reliability calculation, to find the spanning tree; the second phase is a greedy method which searches the optimal network topology based on the spanning ree obtained in the first phase, with considering 2-connectivity. finally, we show some experiments to demonstrate the effectiveness and efficiency of our two phase approach.

Antiproliferative and Anticarcinogenic Enzyme-Inducing Activities of Green Tea Seed Extract in Hepatoma Cells

  • Lim, Hyun-Ae;Jang, Chan-Ho;Kim, Jang-Hoon;Kim, Ju-Ryoung;Ha, Young-Ran;Song, Young-Sun;Kim, Young-Kyoon;Kim, Jong-Sang
    • Food Science and Biotechnology
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    • v.15 no.6
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    • pp.914-919
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    • 2006
  • We investigated the catechin content in green tea leaf (GTL) and green tea seed (GTS), the antiproliferative and detoxifying phase II enzyme-inducing activities of the methanolic (80%, v/v) extracts from GTL and GTS. GTL and GTS contained $8,685{\pm}1,061$ and $108{\pm}32\;{\mu}g/g$ epigallocatechin gallate (EGCG), $11,486{\pm}506$ and $116{\pm}72\;{\mu}g/g$ epigallocatechin (EGC), $3,535{\pm}308$ and $821{\pm}95\;{\mu}g/g$ epicatechin gallate (ECG), and $1,429{\pm}177$ and $37{\pm}44\;{\mu}g/g$ epicatechin (EC), respectively. The methanolic extract of GTS showed a greater increase in quinone reductase activity and antiproliferation potential against mouse hepatoma cells than GTL extract did. GTS treatment resulted in the accumulation at sub-G1 phase of mouse hepatoma hepa1c1c7 cells as assessed by flow cytometry. Enhancement of phase II enzyme activity by GTS extract was shown to be mediated, directly or indirectly, via interaction with the antioxidant response element (ARE) sequence in the genes encoding the phase enzymes. As the catechin content in GTS was significantly lower than that in GTL, components other than catechins appear to be responsible for the anticarcinogenic activity of the seed. In summary, these results suggest that the 80% methanolic extract of GTS deserves further study to evaluate its potential as an anticarcinogenic agent and to investigate its mechanism of action.

Performance Analysis of Complex Phase-code for Phase Multiplexes Holographic Memory System (위상 다중화 홀로그래픽 메모리 시스템을 위한 CPC 위상코드의 성능 분석)

  • 조병철;김정진;김은수
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.1C
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    • pp.1-8
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    • 2003
  • In this paper, performance of the CPC(complex phase code) which is recently proposed as a practical phase encoding method for phase-code multiplexes holographic memory system is comparatively analyzed with those of the conventional phase codes such as PR(pure random code), RCE(random code with equality), WHM(Walsh Hadamard Matrix). In computer simulation, the size of an address bean is fixed at 32$\times$32 pixels and 0%-25% phase-error ratio in a pixel are intentionally added to the real phase values to consider the nonlinear phase-modulation characteristics of the practical spatial light modulator. From comparative analysis of crosstalks and signal-to-noise ratios for these phase codes by calculating auto-correlation and cross-correlation, it is found that the CPC have the lowest cross-correlation mean value of 0.021, the lowest standard deviation of 0.0113 and the highest signal-to-noise ratio(SNR) of 27.4 among the four types of phase code. In addition, from the calculation of the number of all possible address beams for these four types of phase code as the size of the address beam is fixed to 3232 pixels, the CPC is found to have 6.334$\times$10$^{49}$ address beams, which are relatively higher number than that of the conventional phase codes.

Cancellation of MRI Motion Artifact in Image Plane (촬상단면내의 MRI 체동 아티팩트의 제거)

  • Kim, Eung-Kyeu
    • Journal of KIISE:Software and Applications
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    • v.27 no.4
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    • pp.432-440
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    • 2000
  • In this study, a new algorithm for canceling MRI artifact due to translational motion in image plane is described. Unlike the conventional iterative phase retrieval algorithm, in which there is no guarantee for the convergence, a direct method for estimating the motion is presented. In previous approaches, the motions in the x(read out) direction and the y(phase encoding) direction are estimated simultaneously. However, the features of x and y directional motions are different from each other. By analyzing their features, each x and y directional motion is canceled by different algorithms in two steps. First, it is noticed that the x directional motion corresponds to a shift of the x directional spectrum of the MRI signal, and the non-zero area of the spectrum just corresponds to the projected area of the density function on the x-axis. So the motion is estimated by tracing the edges between non-zero area and zero area of the spectrum, and the x directional motion is canceled by shifting the spectrum in inverse direction. Next, the y directional motion is canceled by using a new constraint condition, with which the motion component and the true image component can be separated. This algorithm is shown to be effective by using a phantom image with simulated motion.

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