• Journal of information and communication convergence engineering
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• 제1권1호
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• pp.53-57
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• 2003

Chaos theory is a study researching the irregular, unpredictable behavior of deterministic and non-linear dynamical system. The interpretation using Chaos makes us evaluate characteristic existing in status space of system by tine series, so that the extraction of Chaos characteristic understanding and those characteristics enables us to do high precision interpretation. Therefore, This paper propose the new method which is adopted in extracting character features and recognizing characters using the Chaos Theory. Firstly, it gets features of mesh feature, projection feature and cross distance feature from input character images. And their feature is converted into time series data. Then using the modified Henon system suggested in this paper, it gets last features of character image after calculating Box-counting dimension, Natural Measure, information bit and information dimension which are meant fractal dimension. Finally, character recognition is performed by statistically finding out the each information bit showing the minimum difference against the normalized pattern database. An experimental result shows 99% character classification rates for 2,350 Korean characters (Hangul) using proposed method in this paper.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.835-837
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• 1996

In this paper, a method for the daily maximum load forecasting which uses a chaotic time series in power system and artificial neural network(Back-propagation) is proposed. We find the characteristics of chaos in power load curve and then determine a optimal embedding dimension and delay time. For the load forecast of one day ahead daily maximum power, we use the time series load data obtained in previous year. By using of embedding dimension and delay time, we construct a strange attractor in pseudo phase plane and the artificial neural network model trained with the attractor mentioned above. The one day ahead forecast errors are about 1.4% for absolute percentage average error.

• 소음진동
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• 제7권3호
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• pp.489-498
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• 1997

In this paper, chaotic motions of a curved pipe conveying oscillatory flow are theoretically investigated. The nonliear partial differential equation of motion is derived by Newton's method. The transformed nonlinear ordinary differential equation is a type of Hill's equation, which has the external and parametric excitation with a same frequency. Bifurcation curves of chaotic motion of the piping systems are obtained by applying Melnikov's method. Numerical simulations are performed to demonstrate theoretical results and show the strange attractor of the chaotic motion.

• 음성과학
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• 제3권
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• pp.148-155
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• 1998

As an application of dimensional analysis in the theory of chaos and fractals, we studied and estimated the information dimension for various phonemes. By constructing phase-space vectors from the time-series speech signals, we calculated the natural measure and the Shannon's information from the trajectories. The information dimension was finally obtained as the slope of the plot of the information versus space division order. The information dimension showed that it is so sensitive to the waveform and time delay. By averaging over frames for various phonemes, we found the information dimension ranges from 1.2 to 1.4.

• 음성과학
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• 제4권2호
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• pp.25-39
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• 1998

This paper deals with fuzzy correlation dimension for an appropriate speech recognition. The proposed fuzzy correlation dimension has absorbed time variation value of strange attractor as utilizing fuzzy membership function at calculation of integral correlation when the results of proposed dimension are applied to speech recognition fuzzed correlation dimension is superior to speech recognition, and correlation dimension is superior to speaker discrimination.

• 한국음향학회지
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• 제16권4호
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• pp.42-48
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• 1997

본 논문에서는 음성을 비선형 결정론적 발생메카니즘에서 발생되는 불규칙한 신호인 카오스로 보고 상관차원과 Lyapunov 차원을 구함으로써 음성화자식별 파라미터와 음성인식파라미터에 대한 성능을 평가하였다. Taken의 매립정리를 이용하여 스트레인지 어트렉터를 구성할 때 AR모델의 파워스펙트럼으로부터 주요주기를 구함으로써 정확한 상관차원과 Lyapunov 차원을 추정하였다. 이트렉터 궤도의 특징을 잘 나타내는 상관차원과 Lyapunov 차원을 가지고 음성인식과 화자인식의 특징파라미터로의 효용성을 고찰하였다. 그 결과, 음성인식보다는 화자식별의 특징파라미터로타당하였으며 화자식별 특징파라미터로서는 상관차원보다는 Lyapunov 차원이 높은 화자식별 인식율을 얻을 수 있음을 알았다.

• 소음진동
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• 제7권3호
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• pp.439-447
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• 1997

In this study, the dynamic instabilities of a nonlinear elastic system subjected to follower forces are investigated. The two-degree-of-freedom double pendulum model with nonlinear geometry, cubic spring, and linear viscous damping is used for the study. The constant, the initial impact forces acting at the end of the model are considered. The chaotic nature of the system is identified using the standard methods, such as time histories, power density spectrum, and Poincare maps. The responses are chaotic and unpredictable due to the sensitivity to initial conditions. The sensitivities to parameters, such as geometric initial imperfections, magnitude of follower force, direction control constant, and viscous damping, etc., are analysed. Dynamic buckling loads are computed for various parameters, where the loads are changed drastically for the small change of parameters.

• KIEE International Transactions on Power Engineering
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• 제4A권1호
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• pp.18-25
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• 2004

This paper proposes a totally new method in the chaos characteristics' analysis of power systems, the introduction of topological invariants. Using a return histogram, a bifurcation graph was drawn. As well, the periodic orbits and topological invariants - the local crossing number, relative rotation rates, and linking number during the process of period-doubling bifurcation and chaos were extracted. This study also examined the effect on the topological invariants when the sensitive parameters were varied. In addition, the topological invariants of a three-dimensional embedding of a strange attractor were extracted and the result was compared with those obtained from differential equations. This could be a new approach to state detection and fault diagnosis in dynamical systems.

• 한국정보통신학회논문지
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• 제4권2호
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• pp.379-388
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• 2000

Previous studies on high impedance faults assumed that the erratic behavior of fault current would be random. 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 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. In addition, qualitative analysis such as phase planes, Poincare maps obtained from fault currents indicate that the irregular behavior is described by strange attractor.

• 대한기계학회논문집B
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• 제29권11호
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• pp.1248-1256
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• 2005

This study was undertaken to investigate the flow characteristics of emulsified fuel with the ultrasonic energy-adding system by using the chaotic method. Efffcts of water contents within emulsified fuel, flow rate and tube length with 5m in diameter from an emulsified chamber has been discussed on the strange attractor and power spectral density function. Five probe sensors were set up from 0.5 to 2.5m by length in 0.5m increments in the tube. In particular, the chaotic features of this system have been practically characterized in terms of chaotic statistics such as the power spectral density function and phase space portraits by resorting to the somewhat noble deterministic chaos theory. In the tube, the dominant frequency increased with increasing water contents and flow rate, but decreased a little with an increase in the length from the emulsified chamber.