• Journal of the Korean Institute of Intelligent Systems
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• v.6 no.2
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• pp.72-80
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• 1996

본 논문은 카오스 발생회로(chaos generation circuit)를 설계 및 구현하고, 카오스 회로들간의 카오스 동기화(chaos synchronization) 알고리즘을 기초로 하여 카오스 변조통신을 구성하여 음성비화시스템의 구현에 관하여 실험적으로 검증했다. Pecorra와 Carroll 은 카오스 신호로서 카오스 시스템을 구동하면 카오스 동기화가 가능하다고 발표했다. 이러한 제어기법은 카오스 신호의 마스킹과 복원 알고리즘의 등장을 초래했다. 본 연구는 카오스 신호를 발생하기 위하여 상태변수 기법을 이용하여 로렌쯔(Lorenz) 카오스 발생회로를 하드웨어로 구현했다. 수치 실험 및 보드상의 실험에서 카오스 회로는 카오스의 동적특성을 나타냈으며, 카오스 발생회로들간의 카오스 동기제어를 아루었다. 음성비화를 위한 카오스 신호의 변조는 카오스 신호에 음성신호를 가산하여 송신하며, 광대역)spread spectrum)의 카오스 변조통신 (chaotic modulation communication)에서 음성정보는 수신시스템의 카오스 부시스템에서 카오스 신호를 빼내어 신호를 복원한다. 보드상에서 하드웨어로 구현한 카오스 변.복조 통신시스템을 구성하여 음성신호와 비화통신에 카오스 지능제어기법을 적용하였다.

• The KIPS Transactions:PartD
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• v.13D no.3 s.106
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• pp.437-444
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• 2006

A chaos cipher system that focuses on the stream cipher system has a demerit that the longer the text is, the slower the speed of the encryption and description and the transmission and reception. On this study, we designed the cipher web mail system showing much better capabilities than the existing web mail system as the text is longer. In the embodiment of the cipher web mail system, we developed the key stream, the encryption and description of the text and the inside and outside mail viewer and so on. After the efficiency test, it was valued high in the respect of the speed of the encryption and description and the transmission and reception. And it made up for the defect of the stream cipher system. We expect that we can use it through the persistent applied study in the server system security, the file security, the security of the internet information, the protection of the e-commerce system information and other fields based on the cipher technique as the wide use cipher system that can replace the block cipher system.

• Journal of Mechanical Science and Technology
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• v.17 no.11
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• pp.1714-1724
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• 2003

Feedback strategies of a qualitative competitive game between two players can be designed such as to influence parameters of a mechanical system to induce chaotic behavior. The purpose is to reduce the options and effects of the opponent's strategy. We show it on a case with dynamics specified by a nonautonomous Duffing equation with the players represented by damping and external forcing, respectively. It seems however that the conclusions can be made valid generally.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.106.6-106
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• 2001

In this paper, a four-degree-of-freedom non-linear model is developed to study the dynamic response of vehicle that is caused by the disturbance from the road. The chaotic vibration of the model is investigated with numerical simulation. The model displays complicated dynamic responses including harmonic motions and chaos. It is found that changing of the damping coefficients of the system can eliminate the chaotic response.

• Speech Sciences
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• v.3
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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.

• Speech Sciences
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• v.1
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• pp.285-293
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• 1997

This paper was constructed to investigate strange attractor in considering speech which is regarded as chaos in that the random signal appears in the deterministic raising system. This paper searches for the delay time from AR model power spectrum for constructing fit attractor for speech signal. As a result of applying Taken's embedding theory to the delay time, an exact correlation dimension solution is obtained. As a result of this consideration of speech, it is found that it has more speaker recognition characteristic parameter, and gains a large speaker discrimination recognition rate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.140-144
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• 2004

Global bifurcations and chaos in modal interactions of an imperfect circular plate with one-to-one internal resonance are investigated. The case of primary resonance, in which an excitation frequency is near natural frequencies, is considered. The damping force is not included in the analysis. The Melnikov's method for heteroclinic orbits of the autonomous system was used to obtain the criteria for chaotic motion.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.107-112
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• 1989

We observe experimentally self-pulsing, subharmonic generation, spectral bistability, and chaos in a stable laser diode with delayed optoelectronic feed-back. The laser diode emits 200 ps optical pulses with 1.1 GHz repetition rate in the self-pulsing region. The bistable region critically depends on the closed loop gain of the system. We also explain observed experimental result.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.33-38
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• 2007

Since it is difficult to analytically express the Melnikov function when a dynamic system possesses multiple saddle fixed points with homoclinic and/or heteroclinic orbits, this paper investigates a vehicle model with nonlinear suspension spring and hysteretic damping element, which exhibits multiple heteroclinic orbits in the unperturbed system. First, an algorithm for Melnikov integrals is developed based on the Melnikov method. And then the amplitude threshold of road excitation at the onset of chaos is determined. By numerical simulation, the existence of chaos in the present system is verified via time history curves, phase portrait plots and $Poincar{\acute{e}}$ maps. Finally, in order to further identify the chaotic motion of the nonlinear system, the maximal Lyapunov exponent is also adopted. The results indicate that the numerical method of estimating chaotic threshold is an effective one to complicated vehicle systems.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1581-1587
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• 2006

Today's subway system is packed with various informations such as danger/safety signs, directions, and tightly placed advertisements. All these elements are becoming one big chaos rather than convenient source of information for commuters. To solve this problem immediately, it has to be analysed for systematic character of subway spaces and leaded to constructive improvement for the locating subway signs in correct and convenient spots with right contents. Especially in case of transfer stations, structure is complicated and mazed. At the same time, tremendous amount of commuters are passing through and all these commuting are adding more complications and chaos to the system. Therefore, it is harder to focus on gathering environment informations and finding right directions. Better guiding signage for easier transfer is now essential for new standard of modern commuting with total and logical system. Eventually, it will be great help for setting budget efficiency and advanced subway environment through efficient and Koreanized subway transfer system.