• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.137-140
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• 1993

This paper describes a Chaos analyzer and its applications to characteristic analysis of ECG signals and the other signals. We can detect chaotic system among the various system by quantitative and qualitative analysis using the proposed system. And we also propose a new Possibility to recognize abnormal state of ECG signal using the chaotic characteristcs of signal.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.75-85
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• 1994

주기함수의 외력을 갖는 버선형 시스템의 다양한 응답 특성을 구하기 위해 새로운 조화함수법(HBM)을 적용하였다. 새로운 조화함수법의 해는 비선형항을 선형항으로부터 따로 분리시킨 다음 같은 주파수 성분을 갖는 비선형 방정식들을 Newton-Raphosn법으로 풀어서 구하였다. 다양한 천이(Bifurcation) 특성을 해석적으로 판별하기 위하여 HBM의 해를 이용하여 구한 섭동 방정식의 Floquet 지수의 고유해를 사용하였다. 새로이 개발한 HBM과 천이 판별법을 1차원 비선형항을 갖는 구조물인 ALP(Articulated Loading Platform) 모델과 다차원인 비선 형 회전체 모델에 적용시켜 HBM의 해의 정확성과 이들 시스템의 천이 특성의 하나인 Chaos 존재를 확인 하였다.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.403-405
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• 2003

In this paper, we applied a chaos search method for feeder reconfiguration problem in unbalanced distribution system. Chaos method, in optimization problem, searches the global optimal solution on the regularity of chaotic motions and more easily escapes from local or near optimal solution than stochastic optimization algorithms. The chaos search method applied to the IEEE 13 unbalanced test feeder systems, and the test results indicate that it is able to determine appropriate switching options for global optimum configuration.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2407-2409
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• 2000

Chua's circuit is a simple electronic network which exhibits a variety of bifurcation and attractors. The circuit consists of two capacitors, an inductor, a linear resistor, and a nonlinear resistor. In this paper, a transmitter and a receiver using two identical Chua's circuits are proposed and a equivalent T type wire secure communications are investigated. A secure communication method in which the desired information signal is synthesized with the chaos signal created by the Chua's circuit is proposed and information signal is demodulated also using the Chua's circuit. The proposed method is synthesizing the desired information with the chaos circuit by adding the information signal to the chaos signal in the wire transmission system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.7
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• pp.737-746
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• 2014

Recently, researches about MIMO(Multi-Input Multi-Output) system are being studied actively due to high-capacity and high-speed communication. However, MIMO system has many RF(Radio Frequency) chains according to many array antennas. So, MIMO system has disadvantages such as high-complexity and high-power-consumption. Also, it is impossible to miniaturize the antenna dimension. In order to solve these problems, beamspace MIMO system using ESPAR(Electronically Steerable Parasitic Array Radiator) antenna was proposed. It is possible to reduce the complexity and the power-consumption, because it has single RF chain by using one active antenna and several parasitic elements. In this paper, in order to improve the security, for the first time, chaos communication algorithm is applied to QPSK modulated beamspace MIMO system using ESPAR antenna. We define as chaos QPSK beamspace MIMO system, and evaluate the SER performance. Also, we confirm that QPSK symbols can be made by changing the reactance values of parasitic elements, and evaluate the SER performance of this system.

• Journal of the Korea Society of Computer and Information
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• v.13 no.5
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• pp.155-162
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• 2008

The security of digital image has become increasingly important with the development of the computing performance and internet. Therefore, the encryption algorithms exploiting chaos signal have recently attracted considerable attentions as a new method of image-encryption techniques. In this Paper, it is demonstrated that two different chaotic systems are synchronized by the methods of noise-induced synchronization. Based on this synchronization method, an image-encryption system is implemented and an image of Seok-Ga-Tap is encrypted as a verification of the performance of our system. The method suggested in this paper in which the noise is used as the key of decryption is superior to the existing methods in the aspect of the degree of encryption. In this paper, we Propose that the method is a new effective encryption algorithm as well as an easily applicable one.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.93-99
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• 2006

Methods to distinguish flow regimes in gas-solid fluidized bed have been investigated by adopting the concept of chaos theory. Pressure fluctuations have been chosen as a state variable for the analysis of the system. Pressure fluctuations obtained from differential pressure transducer have been investigated using the chaos analysis (Correlation dimension and Kolmogorov entropy) as well as the average and standard deviation. As a result, fluidization regimes in gas-solid fluidized bed can be distinguished by statistics methods as the average and standard deviation. Also, Correlation dimension and Kolmogorov entropy could be used to classify the fluidization regimes.

• Kyungpook Mathematical Journal
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• v.54 no.2
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• pp.293-320
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• 2014

In this paper, global chaos synchronization is investigated for WINDMI (J. C. Sprott, 2003) and Coullet (P. Coullet et al, 1979) chaotic systems using adaptive backstepping control design based on recursive feedback control. Our theorems on synchronization for WINDMI and Coullet chaotic systems are established using Lyapunov stability theory. The adaptive backstepping control links the choice of Lyapunov function with the design of a controller and guarantees global stability performance of strict-feedback chaotic systems. The adaptive backstepping control maintains the parameter vector at a predetermined desired value. The adaptive backstepping control method is effective and convenient to synchronize and estimate the parameters of the chaotic systems. Mainly, this technique gives the flexibility to construct a control law and estimate the parameter values. Numerical simulations are also given to illustrate and validate the synchronization results derived in this paper.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.721-723
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• 1999

Chua's circuit is a simple electronic network which exhibits a variety of bifurcation and attractors. The circuit consists of two capacitors, an inductor, a linear resistor, and a nonlinear resistor. In this paper, a transmitter and a receiver using two identical Chua's circuits are proposed and a equivalent wire synchronizations are investigated Since the synchronization of the wire transmission system is impossible by coupled synchronization, theory having both the drive-response and the coupled synchronization is proposed. As a result, the chaos synchronization has delay characteristics in the wire transmission system caused by the line parameters L and C.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2525-2527
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• 2000

The analysis of distribution line faults is essential to the proper protection of power system. A high impedance fault(HIF) dose not make enough current to cause conventional protective device operating, so it is well known that undesirable operating conditions and certain types of faults on electric distribution feeders cannot be detected by using conventional protection system. In this paper, we prove that the nature of the high impedance faults is indeed a deterministic chaos, not a random motion. Algorithms for estimating Lyapunov spectrum and the largest Lyapunov exponent are applied to various fault currents detections in order to evaluate the orbital instability peculiar to deterministic chaos dynamically, and fractal dimensions of fault currents which represent geometrical self-similarity are calculated. Wavelet transform analysis is applied the time-scale information to fault signal. Time-scale representation of high impedance faults can detect easily and localize correctly the fault waveform.