• Title/Summary/Keyword: Iteration scheme

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An Implementation of a Thinning Algorithm using FPGA (세선화 알고리즘의 FPGA 구현)

  • Jung, Seung-Min;Yeo, Hyeop-Goo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2013.10a
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    • pp.719-721
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    • 2013
  • A thinning stage of fingerprint algorithm occupies 39% cycle of microprocessor system for identification processing of image from fingerprint sensor. Hardware block processing is more effective than software one in speed and power consumption, because a thinning algorithm is iteration of simple instructions without a transcendental function. This paper describes an effective hardware scheme for thinning stage processing using Verilog-HDL in $64{\times}64$ Pixel Array. The hardware scheme is designed and simulated in RTL. The logic is also synthesized by XST in FPGA environment and tested. Experimental results show the performance of the proposed scheme and possibility of application for a soft microprocessor and thinning processor embedded fingerprint SoC.

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Domain decomposition for GPU-Based continuous energy Monte Carlo power reactor calculation

  • Choi, Namjae;Joo, Han Gyu
    • Nuclear Engineering and Technology
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    • v.52 no.11
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    • pp.2667-2677
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    • 2020
  • A domain decomposition (DD) scheme for GPU-based Monte Carlo (MC) calculation which is essential for whole-core depletion is introduced within the framework of the modified history-based tracking algorithm. Since GPU-offloaded MC calculations suffer from limited memory capacity, employing DDMC is inevitable for the simulation of depleted cores which require large storage to save hundreds of newly generated isotopes. First, an automated domain decomposition algorithm named wheel clustering is devised such that each subdomain contains nearly the same number of fuel assemblies. Second, an innerouter iteration algorithm allowing overlapped computation and communication is introduced which enables boundary neutron transactions during the tracking of interior neutrons. Third, a bank update scheme which is to include the boundary sources in a way to be adequate to the peculiar data structures of the GPU-based neutron tracking algorithm is presented. The verification and demonstration of the DDMC method are done for 3D full-core problems: APR1400 fresh core and a mock-up depleted core. It is confirmed that the DDMC method performs comparably with the standard MC method, and that the domain decomposition scheme is essential to carry out full 3D MC depletion calculations with limited GPU memory capacities.

A Design of Greenhouse Control Algorithm with the Multiple-Phase Processing Scheme (다중 위상 처리구조를 갖는 온실 복합환경제어 알고리즘 설계)

  • Daewook Bang
    • Journal of Service Research and Studies
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    • v.11 no.2
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    • pp.118-130
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    • 2021
  • This study designs and validates a greenhouse complex environmental control algorithm with a multi-phase processing scheme that can combine and control actuators according to the degree of change in the greenhouse environment. The composite environmental control system is a system in which the complex environmental controller analyzes the information detected by sensors and operates appropriately actuators to maintain the crop growth environment. A composite environmental controller directs control devices driving actuators through a composite environmental control algorithm, which calculates the values necessary for the operation of the control devices. Most existing algorithms carry out control procedures on a single phase by iteration cycle, which can cause abnormal changes in the greenhouse environment due to errors in output. The proposed algorithm distributes control procedures over multiple phases: environmental control, environmental control, and device operation, and every iteration cycle, detects environmental changes in the environmental control phase first, and then combines control devices that can control the environment in the environmental control phase, and finally, performs the controls to derive the actuators in the device operation phase. The proposed algorithm is designed based on the analysis of the relationship between greenhouse environmental elements and control devices deriving actuators. According to verification analysis, the multi-phase processing scheme provides room to modify or supplement the setting value and enables the control devices to reflect changes in the associated environmental components.

Implementation of LDPC Decoder using High-speed Algorithms in Standard of Wireless LAN (무선 랜 규격에서의 고속 알고리즘을 이용한 LDPC 복호기 구현)

  • Kim, Chul-Seung;Kim, Min-Hyuk;Park, Tae-Doo;Jung, Ji-Won
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.12
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    • pp.2783-2790
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    • 2010
  • In this paper, we first review LDPC codes in general and a belief propagation algorithm that works in logarithm domain. LDPC codes, which is chosen 802.11n for wireless local access network(WLAN) standard, require a large number of computation due to large size of coded block and iteration. Therefore, we presented three kinds of low computational algorithms for LDPC codes. First, sequential decoding with partial group is proposed. It has the same H/W complexity, and fewer number of iterations are required with the same performance in comparison with conventional decoder algorithm. Secondly, we have apply early stop algorithm. This method reduces number of unnecessary iterations. Third, early detection method for reducing the computational complexity is proposed. Using a confidence criterion, some bit nodes and check node edges are detected early on during decoding. Through the simulation, we knew that the iteration number are reduced by half using subset algorithm and early stop algorithm is reduced more than one iteration and computational complexity of early detected method is about 30% offs in case of check node update, 94% offs in case of check node update compared to conventional scheme. The LDPC decoder have been implemented in Xilinx System Generator and targeted to a Xilinx Virtx5-xc5vlx155t FPGA. When three algorithms are used, amount of device is about 45% off and the decoding speed is about two times faster than convectional scheme.

2D Crank-Nicolson FDTD Method Based on Isotropic-Dispersion Finite Difference Equation for Lossy Media (손실 매질에 대한 Isotropic-Dispersion 유한 차분식의 2D Crank-Nicolson FDTD 기법)

  • Kim, Hyun;Koh, Il-Suek;Yook, Jong-Gwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.7
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    • pp.805-814
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    • 2010
  • The Crank-Nicolson isotropic-dispersion finite difference time domain(CN ID-FDTD) scheme is proposed based on isotropic-dispersion finite difference(ID-FD) $equation^{[1],[2]}$. The dispersion relation of CN ID-FDTD is derived for lossy media by solving the eigenvalue problem of iteration matrix in spatial spectral domain, in addition, the weighting factors and scaling factors of the CN ID-FDTD scheme are presented for low dispersion error. The CN ID-FDTD scheme makes the dispersion error drastically reduced and shows accurate numerical results compared to the conventional Crank-Nicolson FDTD method.

Improvement of Feedback Delay for Practical Distributed Source Coding (실제적인 분산 비디오 부호화를 위한 분산 소스 부호화 시스템의 피드백 지연 문제 개선 방안)

  • Shin, Seung-Shik;Shin, Sang-Yun;Jang, Min;Lim, Dae-Woon;Kim, Sang-Hyo
    • Journal of Broadcast Engineering
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    • v.17 no.1
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    • pp.122-128
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    • 2012
  • Because of the system delay caused by the number of feedback retransmission in Distributed Video Coding (DVC) scheme, it is difficult to realize practical DVC in many cases. In this paper low feedback retransmission Distributed Source Coding (DSC) scheme is proposed for practical DVC scheme based on Low-Density Parity-Check (LDPC) codes because DVC system is an specific application of DSC system. This DSC scheme is achieved by using different LDPC codes optimized in each different compression rate and using source revealing scheme. Optimized LDPC codes provide us much better decoding performance which causes the 57% reduced number of iteration. Consequently, the number of feedback retransmission is decreased by 50%.

Multiple Frequency Offsets Cancellation Scheme Based on Alamouti Coded OFDM for Distributed Antenna Systems in Selective Fading Channel (선택적 감쇄환경에서 분산안테나 간 주파수 오차 환경에 강인한 알라무티부호화 직교주파수분할다중방식 기반 간섭 제거기법)

  • Kim, Bong-Seok;Choi, Kwonhue
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.12
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    • pp.1039-1044
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    • 2013
  • We propose a cancellation algorithm based on Alamouti coded OFDM to mitigate ICI due to Frequency Offset (FO) between distributed antennas in the frequency selective fading channel. In the cancellation algorithm, the interference signal is estimated by using the initial detection symbol and then the estimated interference signal is subtracted from the received signal. As the accuracy of initial symbol increases, ICI cancellation becomes more significant. Therefore, the accuracy of the initial detection symbols is very important in the cancellation algorithm. The proposed scheme improves the accuracy of the initial detection symbol by employing an ICI self-cancellation scheme. The proposed cancellation scheme with only one iteration achieves better performance compared to the conventional cancellation schemes with many times iterations based on the conventional Alamouti coded OFDM.

Iterative Control-Relevant Identification and Controller Enhancement of MIMO Magnetic Bearing Rigid Rotor (반복적 설계 방식을 사용한 다중입출력 자기베어링 시스템의 식별 및 제어기 성능 향상)

  • Han, Dong-Chul;Lee, Sang-Wook;Ahn, Hyeong-Joon;Lee, Sang-Ho
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.493-498
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    • 2000
  • The magnetic bearing systems are intrinsically unstable, and need the feedback control of electromagnetic forces with measured displacements. So the controller design plays an important role in constructing high performance magnetic bearing system. In case of magnetic bearing systems, the order of identified model is high because of unknown dynamics included in closed loop systems - such as sensor dynamics, actuator dynamics-and non-linearity of magnetic bearings itself. "Identification for control" - joint optimization of system identification and controller design- is proposed to get the limited-order model which is suited for the design of high-performance controller. We applied the joint identification/controller design scheme to MIMO rigid rotor system supported by magnetic bearings. Firs, we designed controller of a nonlinear simulation model of MIMO magnetic bearing system with this scheme and proved its feasibility. Then, we performed experiments on MIMO rigid rotor system supported by magnetic bearings, and the performance of closed-loop system is improved gradually during the iteration.

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An artificial neural network residual kriging based surrogate model for curvilinearly stiffened panel optimization

  • Sunny, Mohammed R.;Mulani, Sameer B.;Sanyal, Subrata;Kapania, Rakesh K.
    • Advances in Computational Design
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    • v.1 no.3
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    • pp.235-251
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    • 2016
  • We have performed a design optimization of a stiffened panel with curvilinear stiffeners using an artificial neural network (ANN) residual kriging based surrogate modeling approach. The ANN residual kriging based surrogate modeling involves two steps. In the first step, we approximate the objective function using ANN. In the next step we use kriging to model the residue. We optimize the panel in an iterative way. Each iteration involves two steps-shape optimization and size optimization. For both shape and size optimization, we use ANN residual kriging based surrogate model. At each optimization step, we do an initial sampling and fit an ANN residual kriging model for the objective function. Then we keep updating this surrogate model using an adaptive sampling algorithm until the minimum value of the objective function converges. The comparison of the design obtained using our optimization scheme with that obtained using a traditional genetic algorithm (GA) based optimization scheme shows satisfactory agreement. However, with this surrogate model based approach we reach optimum design with less computation effort as compared to the GA based approach which does not use any surrogate model.

Virtual Resource Allocation in Virtualized Small Cell Networks with Physical-Layer Network Coding Aided Self-Backhauls

  • Cheng, Yulun;Yang, Longxiang;Zhu, Hongbo
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.11 no.8
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    • pp.3841-3861
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    • 2017
  • Virtualized small cell network is a promising architecture which can realize efficient utilization of the network resource. However, conventional full duplex self-backhauls lead to residual self-interference, which limits the network performance. To handle this issue, this paper proposes a virtual resource allocation, in which the residual self-interference is fully exploited by employing a physical-layer network coding (PNC) aided self-backhaul scheme. We formulate the features of PNC as time slot and information rate constraints, and based on that, the virtual resource allocation is formulated as a mixed combinatorial optimization problem. To solve the problem efficiently, it is decomposed into two sub problems, and a two-phase iteration algorithm is developed accordingly. In the algorithm, the first sub problem is approximated and transferred into a convex problem by utilizing the upper bound of the PNC rate constraint. On the basis of that, the convexity of the second sub problem is also proved. Simulation results show the advantages of the proposed scheme over conventional solution in both the profits of self-backhauls and utility of the network resource.