• Title/Summary/Keyword: sequential update

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An Efficient Adaptive Digital Filtering Algorithm for Identification of Second Order Volterra Systems (이차 볼테라 시스템 인식을 위한 효율적인 적응 디지탈 필터링 알고리즘)

  • Hwang, Y.S.;Mathews, V.J.;Cha, I.W.;Youn, D.H.
    • The Journal of the Acoustical Society of Korea
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    • v.7 no.4
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    • pp.98-109
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    • 1988
  • This paper introduces an adaptive nonlinear filtering algorithm that uses the sequential regression(SER) method to update the second order Volterra filter coefficients in a recursive way. Conventionally, the SER method has been used to invert large matrices which result from direct application of Wiener filter theory to the Volterra filter. However, the algorithm proposed in this paper uses the SER approach to update the least squares solution which is derived for Gaussian input signals. In such an algorithm, the size of the matrix to be inverted is smaller than that of conventional approaches, and hence the proposed method is computationally simpler than conventional nonlinear system identification techniques. Simulation results are presented to demonstrate the performance of the proposed algorithm.

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Low Computational Complexity LDPC Decoding Algorithms for DVB-S2 Systems (DVB-S2 시스템을 위한 저복잡도 LDPC 복호 알고리즘)

  • Jung Ji-Won
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.10 s.101
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    • pp.965-972
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    • 2005
  • 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 for second generation digital video broadcasting standard, are required a large number of computation due to large size of coded block and iteration. Therefore, we presented two kinds of low computational algorithm for LDPC codes. First, sequential decoding with partial group is proposed. It has same H/W complexity, and fewer number of iteration's are required at same performance in comparison with conventional decoder algerian. Secondly, 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 computational complexity of early detected method is about $50\%$ offs in case of check node update, $99\%$ offs in case of check node update compared to conventional scheme.

Low Computational Complexity LDPC Decoding Algorithms for 802.11n Standard (802.11n 규격에서의 저복잡도 LDPC 복호 알고리즘)

  • Kim, Min-Hyuk;Park, Tae-Doo;Jung, Ji-Won;Lee, Seong-Ro;Jung, Min-A
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.2C
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    • pp.148-154
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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 are required a large number of computation due to large size of coded block and iteration. Therefore, we presented three kinds of low computational algorithm for LDPC codes. First, sequential decoding with partial group is proposed. It has same H/W complexity, and fewer number of iteration's are required at same performance in comparison with conventional decoder algorithm. Secondly, we have apply early stop algorithm. This method is reduced number of unnecessary iteration. 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.

Location Management using LA-Division Scheme in Personal Communication Systems (이동통신망에서 영역분할 방식의 위치관리 기법)

  • Park, N.Y.;Chang, I.K.;Hong, J.W.;Lie, C.H.
    • IE interfaces
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    • v.16 no.4
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    • pp.507-514
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    • 2003
  • In personal communication systems location management of mobile terminals is required to connect incoming calls to the mobile terminals. Investigation of effective location update and paging strategies is important to reduce the cost of location management. In this study, we propose a paging strategy considering the mobile terminals' residence patterns. The first paging area is characterized by the set of cells in the location area where mobile terminals usually stay for a significant period of time. The rest of cells in the location area are included into the second paging area. To reduce the paging cost the first paging area is decided by reflecting various residence patterns of mobile terminals. For an incoming call, the sequential paging is performed in the order of the paging area. Thus the paging cost is greatly reduced, especially when the called mobile terminal is located in the first paging area. The proposed strategy is expected to be more effective than an existing strategy that uses the anchor cell in the location area.

Hardware Interlocking Security System with Secure Key Update Mechanisms In IoT Environments (IoT 환경에서의 안전한 키 업데이트를 위한 하드웨어 연동 보안 시스템)

  • Saidov, Jamshid;Kim, Bong-Keun;Lee, Jong-Hyup;Lee, Gwang
    • The Journal of the Korea institute of electronic communication sciences
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    • v.12 no.4
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    • pp.671-678
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    • 2017
  • Recent advances in Internet of Things (IoT) encourage us to use IoT devices in daily living areas. However, as IoT devices are being ubiquitously used, concerns onsecurity and privacy of IoT devices are getting grown. Key management is an important and fundamental task to provide security services. For better security, we should restrict reusing a same key in sequential authentication sessions, but it is difficult to manually update and memorize keys. In this paper, we propose a hardware security module(HSM) for automated key management in IoT devices. Our HSM is attached to an IoT device and communicates with the device. It provides an automated, secure key update process without any user intervention. The secure keys provided by our HSM can be used in the user and device authentications for any internet services.

Secure and Efficient Cooperative Spectrum Sensing Against Byzantine Attack for Interweave Cognitive Radio System

  • Wu, Jun;Chen, Ze;Bao, Jianrong;Gan, Jipeng;Chen, Zehao;Zhang, Jia
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.16 no.11
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    • pp.3738-3760
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    • 2022
  • Due to increasing spectrum demand for new wireless devices applications, cooperative spectrum sensing (CSS) paradigm is the most promising solution to alleviate the spectrum shortage problem. However, in the interweave cognitive radio (CR) system, the inherent nature of CSS opens a hole to Byzantine attack, thereby resulting in a significant drop of the CSS security and efficiency. In view of this, a weighted differential sequential single symbol (WD3S) algorithm based on MATLAB platform is developed to accurately identify malicious users (MUs) and benefit useful sensing information from their malicious reports in this paper. In order to achieve this, a dynamic Byzantine attack model is proposed to describe malicious behaviors for MUs in an interweave CR system. On the basis of this, a method of data transmission consistency verification is formulated to evaluate the global decision's correctness and update the trust value (TrV) of secondary users (SUs), thereby accurately identifying MUs. Then, we innovatively reuse malicious sensing information from MUs by the weight allocation scheme. In addition, considering a high spectrum usage of primary network, a sequential and differential reporting way based on a single symbol is also proposed in the process of the sensing information submission. Finally, under various Byzantine attack types, we provide in-depth simulations to demonstrate the efficiency and security of the proposed WD3S.

Optimal feature extraction for normally distributed multicall data (가우시안 분포의 다중클래스 데이터에 대한 최적 피춰추출 방법)

  • 최의선;이철희
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.1263-1266
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    • 1998
  • In this paper, we propose an optimal feature extraction method for normally distributed multiclass data. We search the whole feature space to find a set of features that give the smallest classification error for the Gaussian ML classifier. Initially, we start with an arbitrary feature vector. Assuming that the feature vector is used for classification, we compute the classification error. Then we move the feature vector slightly and compute the classification error with this vector. Finally we update the feature vector such that the classification error decreases most rapidly. This procedure is done by taking gradient. Alternatively, the initial vector can be those found by conventional feature extraction algorithms. We propose two search methods, sequential search and global search. Experiment results show that the proposed method compares favorably with the conventional feature extraction methods.

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A Study of Automatic Multi-Target Detection and Tracking Algorithm using Highest Probability Data Association in a Cluttered Environment (클러터가 존재하는 환경에서의 HPDA를 이용한 다중 표적 자동 탐지 및 추적 알고리듬 연구)

  • Kim, Da-Soul;Song, Taek-Lyul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.10
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    • pp.1826-1835
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    • 2007
  • In this paper, we present a new approach for automatic detection and tracking for multiple targets. We combine a highest probability data association(HPDA) algorithm for target detection with a particle filter for multiple target tracking. The proposed approach evaluates the probabilities of one-to-one assignments of measurement-to-track and the measurement with the highest probability is selected to be target- originated, and the measurement is used for probabilistic weight update of particle filtering. The performance of the proposed algorithm for target tracking in clutter is compared with the existing clustering algorithm and the sequential monte carlo method for probability hypothesis density(SMC PHD) algorithm for multi-target detection and tracking. Computer simulation studies demonstrate that the HPDA algorithm is robust in performing automatic detection and tracking for multiple targets even though the environment is hostile in terms of high clutter density and low target detection probability.

Optimal reinforcement design of structures under the buckling load using the homogenization design method

  • Min, Seungjae;Kikuchi, Noboru
    • Structural Engineering and Mechanics
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    • v.5 no.5
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    • pp.565-576
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    • 1997
  • The material-based homogenization design method generates arbitrary topologies of initial structural design as well as reinforcement structural design by controlling the amount of material available. However, if a small volume constraint is specified in the design of Lightweight structures, thin and slender structures are usually obtained. For these structures stability becomes one of the most important requirements. Thus, to prevent overall buckling (that is, to increase stability), the objective of the design is to maximize the buckling load of a structure. In this paper, the buckling analysis is restricted to the linear buckling behavior of a structure. The global stability requirement is defined as a stiffness constraint, and determined by solving the eigenvalue problem. The optimality conditions to update the design variables are derived based on the sequential convex approximation method and the dual method. Illustrated examples are presented to validate the feasibility of this method in the design of structures.

Update on the Evidence Regarding Maintenance Therapy

  • Lee, Jeong Eun;Chung, Chae-Uk
    • Tuberculosis and Respiratory Diseases
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    • v.76 no.1
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    • pp.1-7
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    • 2014
  • Maintenance therapy has emerged as a novel therapeutic paradigm for advanced non-small-cell lung cancer (NSCLC). Maintenance therapy that aims to sustain a clinically favorable state after first-line chemotherapy has two strategies. Switch maintenance therapy entails switching to a new and non-cross-resistant agent in an alternating or sequential manner, on completion of first-line chemotherapy. Continuous maintenance therapy keeps ongoing administration of a component of the current regimen after four to six cycles of chemotherapy, if there is a stable disease, or better response. Both maintenance therapies can be continued, until disease progression. The potential evidence regarding maintenance therapy includes providing the opportunity to receive additional treatment, through sustaining tumor shrinkage, and delayed emergence of tumor-related symptom. Thus far, debates over the parameters used to predict the effectiveness of maintenance therapy, financial burden, and uncertainty of improving the quality of life exist. Despite many debates, maintenance therapy, which is currently recommended, has been disclosed to be beneficial.