• Title, Summary, Keyword: 카오스

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Isolated Digit Recognition Combined with Recurrent Neural Prediction Models and Chaotic Neural Networks (회귀예측 신경모델과 카오스 신경회로망을 결합한 고립 숫자음 인식)

  • Kim, Seok-Hyun;Ryeo, Ji-Hwan
    • Journal of the Korean Institute of Intelligent Systems
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    • v.8 no.6
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    • pp.129-135
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    • 1998
  • In this paper, the recognition rate of isolated digits has been improved using the multiple neural networks combined with chaotic recurrent neural networks and MLP. Generally, the recognition rate has been increased from 1.2% to 2.5%. The experiments tell that the recognition rate is increased because MLP and CRNN(chaotic recurrent neural network) compensate for each other. Besides this, the chaotic dynamic properties have helped more in speech recognition. The best recognition rate is when the algorithm combined with MLP and chaotic multiple recurrent neural network has been used. However, in the respect of simple algorithm and reliability, the multiple neural networks combined with MLP and chaotic single recurrent neural networks have better properties. Largely, MLP has very good recognition rate in korean digits "il", "oh", while the chaotic recurrent neural network has best recognition in "young", "sam", "chil".

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A Chaos Characteristic Analysis of Nonlinear Rainfall-Runoff Data (비선형 강우-유출량 자료에 대한 카오스 특성 분석)

  • Park, Sung-Chun;Jin, Young-Hoon;Oh, Chang-Ryol
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.614-618
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    • 2005
  • 수문시계열 분석과 예측은 대부분 ARMA(AutoRegressive Moving Average) 형태의 선형적인 추계학적인 모형을 이용하였으나 자현현상이 복잡해지고 비선형적인 특성을 가짐에 따라 선형적인 해석은 수문시계열의 분석과 예측에 있어서 많은 오류를 내포하고 있다. 이와 같은 문제를 해결하기 위한 시도로 Chaos이론이란 개념이 사용되기 시작하였으며, 수자원분야에서는 1980년대 후반부터 물수지 방정식 및 강우유출에 대한 카오스적 특성분석 등 많은 연구가 진행되었다. 본 연구에서는 영산강유역의 본류를 대표하는 나주지점을 대상으로 2003년 1월 1일 00시부터 2004년 12월 31일 23시까지 17,544개의 시수위 자료에 대하여 해당 년도의 Rating-Curve식을 적용 환산한 유출량자료에 데한 카오스적 특성을 분석하였다. 카오스적 특성을 분석하기에 앞서 원자료에 대하여 이동평균법과 Savitzky-Golay Filter를 적용하여 잡음을 제거하였으며, 1차원의 단일변량의 자료에 대한 상태공간(Phase Space)의 재건을 통하여 비교검토 하였다. 이러한 일련의 과정을 거친 자료에 대하여 상관차원법을 이용하여 영산강 유역의 나주지점의 시유출량 자료에 대한 카오스적 특성을 분석한 결과 저차원의 수렴으로 카오스 특성을 가졌다.

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Wavelet-based Digital Watermarking with Chaotic Sequences (카오스 시퀀스를 이용한 웨이브릿-기반 디지털 워터마크)

  • 김유신;김민철;원치선;이재진
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.1B
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    • pp.99-104
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    • 2000
  • In this paper, as a digital watermark we propose to use a chaotic sequence instead of the conventional Gaussian sequence. It is relatively easy to generate the chaotic sequence and is very sensitive to the change of initial value. The chaotic sequence adopted in this paper is a modified version of logistic map to give the sequence distribution of Chebyshev map. In the experiments, we applied the Gaussian sequence and chaotic sequence to wavelet coefficients of images to compare the similarity distribution. The results show that, as id the DCT-based watermarking system, the chaotic sequence is robust for various signal processing attacks, Moreover, the similarity variance is smaller than the Gaussian sequence for iterative experiments. It also shows a better performance for compression errors than the Gaussian sequence.

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Design and Implementation of a Chaotic Oscillator for UWB (UWB용 카오스 오실레이터의 설계 및 구현)

  • Kang, Sang-Gee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.12
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    • pp.2136-2139
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    • 2008
  • Chaotic oscillators can generate wide-band signals and the spectrum characteristics of the wide-band signals are not changed by switching on and off the output power of the oscillators. When communication systems use a chaotic oscillator, the communication system need not a local oscillator and a mixer used in conventional transceivers. Therefore the configuration of a communication system using a chaotic oscillator is simple and have the characteristics of low-power consumption. In this paper we design and implement a chaotic oscillator. And the test results of the implemented chaotic oscillator for UWB systems are presented. The implemented chaotic oscillator has -8.11dBm of the output power with 500MHz channel bandwidth at 3.4GHz of the center frequency and has about 410MHz of -10dB bandwidth.

Comparative Evaluation of Modem Technique in Nonsynchronous Chaos Secure Communication (비동기 카오스 비밀통신의 변복조 기술평가)

  • 최희주;배준호;김성곤;변건식
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.178-182
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    • 2000
  • During the past five years, there has born tremendous interest worldwide in the possibility of exploiting chaos in wideband communication systems. Many different demodulation techniques have been proposed up to date. They can be divided into two basic categories. In the first approach, like the conventional coherent demodulation techniques, the chaotic signal has to be recovered from the received noisy signal by synchronization. However, the chaotic synchronization techniques published to data are so sensitive to the channel noise and distortion that these techniques can not be used in radio communications. In the second approach, the demodulation is carried out nonsynchronization. This paper surveys the different chaotic communication techniques that can be implemented nonsynchronization and compares the threshold and BER of the different methods. Finally, FM-DCSK is introduced the first step for apply to wideband chaos digital CDMA, where the data is not limited by the inherent nonperiodic property of the chaotic signal.

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A Study for Estimation of Link Travel Time Using Chaos Theory (카오스이론을 이용한 링크통행시간 산정)

  • 노승만;이인원
    • Journal of Korean Society of Transportation
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    • v.17 no.2
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    • pp.115-126
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    • 1999
  • Past nears many Studies have been described for present state and forecasted for the future phenomena in various areas. Many theories and methodologies in transportation have been developed and applied by researchers and planners. On the other hand, many theories and methodologies had disappeared caused by their critical limitations. One of this cause that was discovered of the Chaos in traffic flows. The occurrence of Chaos in traffic flows has affected to the traffic volume and decreased significancy of a simulation result of a specific traffic flow. According to this fact, long-term forecast of traffic flow is difficult, moreover a butterfly effect impedes development and establishment of transportation model. A methodology to solve Chaos character in traffic flow can be able to provide more effective transport planning. This study tackles to enhance and revise the existing theories for the traffic flow applying Chaos theory to estimating travel time.

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Design and Implementation of a Web Security System using a Chaos Cipher Algorithm (카오스 암호화 알고리즘을 이용한 웹 보안 시스템 설계 및 구현)

  • Lee, Bong-Hwan;Kim, Cheol-Min;Yun, Dong-Won;Chae, Yong-Ung;Kim, Hyeon-Gon
    • The KIPS Transactions:PartC
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    • v.8C no.5
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    • pp.585-596
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    • 2001
  • In this paper, a new stream cipher algorithm based on the chaos theory is proposed and is applied to a Web security system. The Web security system is composed of three parts: certificate authority (CA), Web client, and Web server. The Web client and server system include a secure proxy client (SPC) and a secure management server (SMS), respectively, for data encryption and decryption between them. The certificate is implemented based on X.509 and the RSA public key algorithm is utilized for key creation and distribution to certify both the client and server. Once a connection is established between the client and server, outgoing and incoming data are encrypted and decrypted, respectively, using one of the three cipher algorithms: chaos, SEED, and DES. The proposed chaos algorithm outperforms the other two conventional algorithms in processing time and complexity. Thus, the developed Web security system can be widely used in electronic commerce (EC) and Internet banking.

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Design of image encryption system using multiple chaotic maps (다중 카오스 사상을 이용한 영상 암호시스템 설계)

  • 이성우;신재호
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.14 no.4
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    • pp.183-194
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    • 2004
  • The proliferation of the Internet and the rapid progress of wire/wireless communication technology makes security of digital images more and more important since the exchanges of digital images occur more and more frequently. And as the tight relationship between chaos theory and cryptography, many researches for development of new encryption systems based on chaotic maps have been widely progressed recently. In this paper, we propose a digital image encryption system based on both one-dimensional PLCM(Piecewise Linear Chaotic Map) and two-dimensional baker map. This proposed system is a product cipher that contains a perturbance-based chaotic stream cipher based on ID PLCM and a chaotic block cipher based on 2D baker map and is very high secure and easily implementable cipher having both a good confusion property and a good diffusion property. And with test results, we showed this system is very secure against statistical attacks.

Influence of Noise on Chaotic Time Series (카오스 시계열에 대한 잡음의 영향)

  • Choi, Min-Ho;Lee, Eun-Tae;Kim, Hung-Soo
    • Journal of Korea Water Resources Association
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    • v.42 no.4
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    • pp.355-363
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    • 2009
  • The purpose of this paper is to investigate the influence of noise on chaotic time series. We used two time series of Lorenz system and of Great Salt Lake's volume data which are well known as chaotic systems. This study investigated the attractors, correlation dimensions, and Close Returns Plots and Close Returns Histograms of two time series to investigate the influence of noise as increasing noise level. We performed Chi-square test to the relative frequency of Close Returns Histogram from Close Returns Plot for the investigation of stochastic process of chaotic time series as increasing noise level of time series. As the results, two time series were changed from chaotic to stochastic series as noise level is increased. Finally, we analyzed the effect of noise cancellation by using Simple Moving Average method. The results of applications of Simple Moving Average method to Lorenz and GSL time series showed that we could effectively cancel the noise. Then we could confirm the applicability of Simple Moving Average method to cancel the noise for the hydrologic time series having chaotic characteristics.