• Title/Summary/Keyword: 신호탐지 이론

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Design of Network Attack Detection and Response Scheme based on Artificial Immune System in WDM Networks (WDM 망에서 인공면역체계 기반의 네트워크 공격 탐지 제어 모델 및 대응 기법 설계)

  • Yoo, Kyung-Min;Yang, Won-Hyuk;Kim, Young-Chon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.4B
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    • pp.566-575
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    • 2010
  • In recent, artificial immune system has become an important research direction in the anomaly detection of networks. The conventional artificial immune systems are usually based on the negative selection that is one of the computational models of self/nonself discrimination. A main problem with self and non-self discrimination is the determination of the frontier between self and non-self. It causes false positive and false negative which are wrong detections. Therefore, additional functions are needed in order to detect potential anomaly while identifying abnormal behavior from analogous symptoms. In this paper, we design novel network attack detection and response schemes based on artificial immune system, and evaluate the performance of the proposed schemes. We firstly generate detector set and design detection and response modules through adopting the interaction between dendritic cells and T-cells. With the sequence of buffer occupancy, a set of detectors is generated by negative selection. The detection module detects the network anomaly with a set of detectors and generates alarm signal to the response module. In order to reduce wrong detections, we also utilize the fuzzy number theory that infers the degree of threat. The degree of threat is calculated by monitoring the number of alarm signals and the intensity of alarm occurrence. The response module sends the control signal to attackers to limit the attack traffic.

A Study on the Linear Array Beamforming by Spatial Cross Correlation Matrix (공간 상호상관 행렬을 이용한 선배열 빔형성 기법 연구)

  • Hwang Soo-Bok;Lee Sung-Eun
    • Proceedings of the Acoustical Society of Korea Conference
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    • spring
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    • pp.177-180
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    • 2000
  • 소나 시스템에서는 신호 대 잡음비의 향상, 표적의 방위탐지 및 위치 데이터 산출, 간섭신호 제거 등을 위하여 지향성 빔을 만들어 사용한다. 본 논문에서는 선형으로 배열된 센서에서 각 센서쌍들에 대한 상호상관 행렬을 이용한 SCCBF(Spatial Cross Correlation Beamformer) 알고리즘을 제안하였다 이상적인 조건하에서 제안된 SCCBF는 CBF(Conventional Beamformer)에 비해 3dB의 Array Gain을 갖는 것을 이론적으로 검증하고 표적의 탐지 방위정확도를 나타내는 빔폭(Beam Width)이 CBF 보다 0.5배정도가 됨을 검증하고 모의실험을 통하여 이를 입증하였다.

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Analysis of the ES detection loss related to the circular scan of radars (레이더의 원형 스캔에 따른 ES 탐지손실 분석)

  • Ryoo, Young-Jin;Kim, Whan-Woo
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.42 no.6
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    • pp.159-166
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    • 2005
  • The pulse amplitude of a search radar signal received by an ES system is not constant pulse by pulse because of the radar's scan characteristics. The variation of the pulse amplitude causes the ES detection loss in the ES system. Therefore, the ES detection range equation should consider the ES detection loss caused by the search radar's scan characteristics. In this paper, we theoretically analyze the ES detection loss for the circular scar and propose the model to evaluate it quantitatively. The experiment results for the real search radar signals demonstrate that the proposed model is suitable for the evaluation model of the ES detection loss related to the circular scan of radars.

Compressive Sensing-Based L1-SVD DOA Estimation (압축센싱기법 기반 L1-SVD 도래각 추정)

  • Cho, Yunseong;Paik, Ji-Woong;Lee, Joon-Ho;Ko, Yo Han;Cho, Sung-Woo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.27 no.4
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    • pp.388-394
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    • 2016
  • There have been many studies on the direction-of-arrival(DOA) estimation algorithm using antenna arrays. Beamforming, Capon's method, maximum likelihood, MUSIC algorithms are the main algorithms for the DOA estimation. Recently, compressive sensing-based DOA estimation algorithm exploiting the sparsity of the incident signals has attracted much attention in the signal processing community. In this paper, the performance of the L1-SVD algorithm, which is based on fitting of the data matrix, is compared with that of the MUSIC algorithm.

Design and analysis of direction indicating algorithm for sound reception system based on spectral analysis of whistle signal (기적신호의 스펙트럼 분석을 통한 음향수신장치의 방향탐지 알고리즘 설계 및 분석)

  • Kwon, Hyuk-Jin;Kim, Jeong-Chang
    • Journal of Advanced Marine Engineering and Technology
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    • v.41 no.1
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    • pp.83-90
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    • 2017
  • In this paper, a sound reception system using a phase difference of whistle signals is proposed and analyzed based on spectral analysis. The proposed system receives whistle signals from four microphones installed in four different directions with 90-degree intervals between them. The proposed algorithm detects the phase of each received signal based on spectral analysis and estimates the direction of the whistle signal by obtaining the phase difference between the received signals from two adjacent microphones. Furthermore, we theoretically analyze the phase difference between two adjacent received signals according to their arrival angles and implement the proposed system using a DSP chip. In addition, the operation of the proposed algorithm are verified using the implemented system in a laboratory environment. Experimental results show that the proposed scheme can well estimate the direction of the whistle signal.

Performance Analysis of Direction Finding Systems Using EM Simulation-based Array Manifolds (EM 시뮬레이션 기반의 어레이 매니폴드를 이용한 방향 탐지 시스템 성능 분석)

  • Kim, Jae-Hwan;Cho, Chihyun
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.10
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    • pp.1166-1172
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    • 2012
  • In this paper, by using a commercial EM simulator, we could obtain the array manifold which are phase responses of an array antenna for the incident plane wave and then verified the effectiveness of methodology after comparing with the measurement. The result shows that the array manifold can be calculated including not only the phase response of the ideal point sources but also the influences of the mutual coupling between antennas and the installed platform. Also it can exclude the interference of strong broadcasting signal and the disturbance of the multipath in the calibration process. Finally, to predict the performances of direction finding systems, a novel method using both the EM simulation-based receiving signal and the sparsely sampled array manifold with the parabolic estimation is proposed. This method can be utilized in the various fields of direction-finding since it shows the superior predictive performance even in low SNR conditions.

Leak Location Detection of Underground Water Pipes using Acoustic Emission and Acceleration Signals (음향방출 및 가속도 신호를 이용한 지하매설 상수도배관의 누수지점 탐지연구)

  • Lee, Young-Sup;Yoon, Dong-Jin;Jeong, Jung-Chae
    • Journal of the Korean Society for Nondestructive Testing
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    • v.23 no.3
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    • pp.227-236
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    • 2003
  • Leaks in underground pipelines can cause social, environmental and economical problems. One of relevant countermeasures against leaks is to find and repair of leak points of the pipes. Leak noise is a good source to identify the location of leak points of the pipelines. Although there have been several methods to detect the leak location with leak noise, such as listening rods, hydrophones or ground microphones, they have not been so efficient tools. In this paper, acoustic emission (AE) sensors and accelermeters are used to detect leak locations which could provide all easier and move efficient method. Filtering, signal processing and algorithm of raw input data from sensors for the detection of leak location are described. A 120m-long pipeline system for experiment is installed and the results with the system show that the algorithm with the AE sensors and accelerometers offers accurate pinpointing of leaks. Theoretical analysis of sound wave propagation speed of water in underground pipes, which is critically important in leak locating, is also described.

Understanding the Effects of the Dispersion and Reflection of Lamb Waves on a Time Reversal Process (램파의 분산성과 파 반사가 시간반전과정에 미치는 영향의 이해)

  • Park, Hyun-Woo;Kim, Sung-Bum;Sohn, Hoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.1
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    • pp.89-103
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    • 2009
  • This study investigates the applicability of the time reversal concept in modem acoustics to the Lamb waves, which have been widely studied for defect detection in plate-like structures. According to conventional time reversal acoustics, an input signal can be reconstructed at an excitation point if an output signal recorded at another point is reversed in the time domain and emitted back to the original source point. However, the application of a time reversal process(TRP) to Lamb wave propagations is complicated due to velocity and amplitude dispersion characteristics of Lamb waves and reflections from the boundaries of a structure. In this study, theoretical investigations are presented to better understand the time reversibility of Lamb waves. In particular, the effects of within-mode dispersion, multimode dispersion, amplitude dispersion, and reflections from boundaries on the TRP are theoretically formulated. Simple numerical case studies are conducted to validate the theoretical findings of this study.

Detection of unexploded ordnance (UXO) using marine magnetic gradiometer data (해양 자력구배 탐사자료를 이용한 UXO 탐지)

  • Salem Ahmed;Hamada Toshio;Asahina Joseph Kiyoshi;Ushijima Keisuke
    • Geophysics and Geophysical Exploration
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    • v.8 no.1
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    • pp.97-103
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    • 2005
  • Recent development of marine magnetic gradient systems, using arrays of sensors, has made it possible to survey large contaminated areas very quickly. However, underwater Unexploded Ordnances (UXO) can be moved by water currents. Because of this mobility, the cleanup process in such situations becomes dynamic rather than static. This implies that detection should occur in near real-time for successful remediation. Therefore, there is a need for a fast interpretation method to rapidly detect signatures of underwater objects in marine magnetic data. In this paper, we present a fast method for location and characterization of underwater UXOs. The approach utilises gradient interpretation techniques (analytic signal and Euler methods) to locate the objects precisely. Then, using an iterative linear least-squares technique, we obtain the magnetization characteristics of the sources. The approach was applied to a theoretical marine magnetic anomaly, with random errors, over a known source. We demonstrate the practical utility of the method using marine magnetic gradient data from Japan.

Design and Fabrication of Compressive Receiver for RFID Signal Detection (RFID 신호 탐지용 컴프레시브 수신기의 설계 및 제작)

  • Jo, Won-Sang;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.3
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    • pp.321-330
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    • 2010
  • In this paper, the theoretical background and the specific implementation method of a compressive receiver for RFID signal detection as well as the design method of DDL(Dispersive Delay Line) and chirp LO are described. DDL, which is one of the main components of the compressive receiver, is designed to have $13{\mu}s$ dispersive delay time and 6 MHz bandwidth using the SAW technique based on $LiNbO_3$ material. The chirp LO is designed using DDS(Direct Digital Synthesizer). Also the compressive receiver is fabricated to be installed into the RFID reader. Test results show the maximum frequency error of 25 kHz for single signal input, the receiver sensitivity of -44 dBm, and the maximum frequency error is 75 kHz for 6 multi-tone input signals. These results indicate that the fabricated compressive receiver is working well even in dense RFID operating environments.