• 제목, 요약, 키워드: 카오스

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Nonlinear Forecasting of Daily Runoff Using Inverse Approach Method (가역접근법을 이용한 일유출량 자료의 비선형 예측)

  • Lee, Bae-Sung;Jeong, Dong-Kug;Jung, Tae-Sung;Lee, Sang-Jin
    • Journal of Korea Water Resources Association
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    • v.39 no.3
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    • pp.253-259
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    • 2006
  • In almost all previous hydrological studies, the standard approach adopted for nonlinear time series analysis is to perform system characterization first followed by forecasting. However, a practical inverse approach for forecasting nonlinear hydrological time series was proposed recently To investigate the applicability standard approach method and inverse approach, this study used a theoretical time series (Mackey-Glass time series) and daily streamflows of the Bear River in Idaho. To predict a theoretical time series and daily streamflow, this study used local approximation method. From chaos analysis, chaotic characteristics are found in daily streamflow of the Bear River in Idaho. Resulting from 1, 3 and 5-day prediction, inverse approach method is shown to be better than the standard approach for a theoretical chaotic time series and daily streamflow.

Microcontroller based Chaotic Lorenz System for Secure Communication Applications (암호통신 응용을 위한 마이크로 컨트롤러 기반 로렌츠 카오스 시스템)

  • Jayawickrama, Chamindra;Song, Hanjung
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.12
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    • pp.1698-1704
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    • 2018
  • This paper presents a implementation of a chaotic Lorenz system for data secure communication applications. Here we have used PIC18F family-based microcontroller to generate the chaotic signal, and simulated waveform patterns confirm that the chaotic behavior of the microcontroller based discrete time chaotic Lorenz system. There are three R-2R ladder type A/D converters have been implemented for conversion of direct microcontroller digital output into analog waveform, utilizing this specific microcontroller relevant to this experiment work, microcontroller ports B, C and D have been utilized for its time waveform outputs X, Y and Z respectively. XC8 compiler used for the compilation of the program. MATLAB and PROTEUS software platforms are used for simulation. Finally, chaotic time wave forms, 2D chaotic attractors were obtained and secure communication analog waveforms were also verified by experimental measurement.

Integrated Circuit Design and Implementation of the Voltage Controlled Chaotic Circuit (전압제어형 카오스회로의 집적회로 설계 및 구현)

  • 송한정;곽계달
    • Journal of the Korean Institute of Telematics and Electronics C
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    • v.35C no.12
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    • pp.77-84
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    • 1998
  • A voltage controlled chaotic circuit has been designed in integrated circuit and fabricated by using 0.8$\mu\textrm{m}$ single poly CMOS technology. The fabricated chaotic circuit consist of sample and hold circuits, op-amps, nonlinear function generator and two phase clock generator. The test results of the chaotic circuit show that periodic state, quasi-periodic state and chaotic state can be obtained according to the input control voltage with the ${\pm}$2.5V power supply and clock rate of 20kHz. In addition, two dimensional chaotic patterns have been observed by connecting this circuit in parallel or series

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Chaotic Disaggregation of Daily Rainfall from the Climate Change Scenarios (기후변화 시나리오에 따른 일 강우자료의 카오스적 시간분해)

  • Kyoung, Min-Soo;Sivakumar, Bellie;Kim, Hung-Soo;Kim, Byung-Sik
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.178-183
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    • 2008
  • 지구온난화로 인한 기후변화가 기정사실화 되면서 이러한 기후변화에 대비하기 위한 다양한 연구가 진행중이다. 수자원과 관련된 기후변화 연구를 살펴보면 초기에는 장기적 관점에서 기후변화가 유출에 미치는 영향에 대한 연구가 대부분을 이루고 있었으나 2003년을 기점으로 유럽을 중심으로 기후변화가 홍수량에 미치는 영향에 대한 연구가 시작되었다. 기후변화가 홍수에 미치는 영향을 평가하는데 가장 중요한 것은 수문시계열 자료의 해상도라고 할 수 있다. 이러한 시공간적 해상도 문제를 해결하기 위해서 세계 각국은 각국의 상황에 맞는 RCM을 개발하고 있으며 자국에 적합한 축소기법을 개발하고자 노력하고 있다. 따라서 본 연구에서는 고해상도 수문기상자료의 생성을 위하여 기후변화 모형으로부터 생성된 일 단위 강우자료를 시자료로 분해하기 위한 기법을 제시하고자한다. 지난 수십년 동안 강우나 기타 수문시계열 자료를 다양한 해상도의 자료로 변환하기 위한 연구가 진행되어왔다. 그러나 이러한 연구의 가장 큰 한계점은 대부분의 시계열 자료가 추계학적 특성을 가지고 있다고 가정한 후, 분석을 진행했다는 것이다. 이렇게 되면 강우발생에 따른 물리적 과정을 모형의 구조에 반영하는데 한계점을 드러내게 된다. 따라서 본 연구에서는 해상도를 변화시키는데 따른 강우의 운동역학적 특성을 고려하기 위하여 카오스를 기반으로 한 분해기법을 제시하고자 한다. 우선 카오스 분석을 통해서 지점 강우자료의 카오스 특성을 확인한 후, 현재까지 관측된 강우를 기반으로 $2CO_2$에서의 일 강우를 일 단위 보다 작은 단위로 분해하였다.

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A New Light Cryptosystem with a Discretized Chaotic Functions (이산화된 카오스 함수를 이용한 새로운 경량의 암호 시스템)

  • Lim, Dae-Woon;Yang, Gi-Joo;An, Ta-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.12C
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    • pp.977-983
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    • 2010
  • The output values of chaotic functions look highly unpredictable and random-like. These features are in accord with the requirements for secure cryptosystems. For this reason, many kinds of cryptosystems using chaotic functions have been proposed so far. However, most of those algorithms are not applicable for light cryptosystems because they need a high level of computing ability. In this paper, we propose a new light chaotic cryptosystems which are suitable for the systems with a low level of computing ability. From the simulations, we show the performance of proposed cryptosystems on computational complexity and security level.

Chaotic dynamics of the multiplier based Lorenz circuit (곱셈기 기반 로렌츠 회로의 카오스 다이내믹스)

  • Ji, Sung-hyun;Song, Han-Jung
    • Journal of the Korean Institute of Intelligent Systems
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    • v.26 no.4
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    • pp.273-278
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    • 2016
  • In this paper, chaotic circuit of the Lorentz system using multipliers, operational amplifiers, capacitor, fixed resistor and variable resistor for control has been designed in a electronic circuit. Through PSPICE program, electrical characteristics such as time waveforms, frequency spectra and phase attractors analyzed. And in the special area ($10{\sim}100k{\Omega}$) of the $500k{\Omega}$ control variable resistor, the circuit showed chaotic dynamics. Also, we implemented the circuit in a electronic hardware system with discrete elements. Measured results of the circuit coincided with simulated data.

Nonlinear Analysis in Love Dynamics with Triangular Membership Function as External Force (삼각 퍼지 소속 함수를 외력으로 가진 사랑 동력학에서의 비선형 해석)

  • Bae, Young-Chul
    • Journal of Digital Contents Society
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    • v.18 no.1
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    • pp.217-224
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    • 2017
  • Recently, we have been continued effort that chaotic theory apply into love model which is an area of social science. To make the chaotic behaviors in the differential equation that represent as Romeo and Juliet, we apply an external force to the differential equation. However, this external force have disadvantage that cannot exactly represent for emotion of human. In this paper, to solve these advantage, we introduce triangular fuzzy membership function to provide the external force that can describe most similar status for action and word of human in the love model of Romeo and Juliet. Also, to confirm the chaotic behaviors in the love model of Romeo and Juliet with proposed fuzzy membership function, we use time series and phase plane.

Chaos Theory: An Alternative for a Paradigm Shift in the Social Science Studies (사회과학연구 패러다임 변화대안으로서의 카오스 이론)

  • Kim, Min Sun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.11
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    • pp.6621-6629
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    • 2014
  • Social phenomena require the fundamentals of novel scientific epistemology and methodology due to the continual change by complex variables. A systematic understanding of paradigm shifts is also necessary for analyzing the problems currently faced in society. This study presents chaos theory, which was developed from the natural sciences, to discuss the abnormality of modern society that underscores the importance of the chaos paradigm. Chaos theory is applicable to diverse social phenomena that stretches across politics, economics, and sociology. If social science research can appropriately and effectively develop and apply chaos theory, the theory can be utilized as a useful paradigm to reinforce the fundamentals of epistemology and methodology in exploring social phenomena.

Temperature Analysis of the Voltage Contolled Chaotic Circuit (전압 제어형 카오스회로의 온도특성 해석)

  • Park, Yongsu;Zhou, Jichao;Song, Hanjung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.8
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    • pp.3976-3982
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    • 2013
  • This paper presents a temperature analysis of the chaotic behavior in the voltage controlled CMOS chaotic circuit. The circuit is based on a simple nonlinear function block which is needed for chaotic signal generation. It consists of a NFB (nonlinear function block), a level shifter and non-overlapping two-phase clock for sample and hold. By SPICE simulation, chaotic dynamics such as frequency spectra and bifurcations according to the temperature variations were analyzed. And, it was showed that the circuit can generate discrete chaotic signals within control voltage in the range from 1.2 V to 2.3 V in a specific temperature condition of $25^{\circ}C$.

Chaotic Phenomenon in Rolling Mill Bearing (압연기 베어링에서의 카오스 현상에 관한 연구)

  • 배영철;김주완
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.157-160
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    • 2001
  • 회전체 베이링 상태진단에 신뢰성을 갖기 위하여 여러 가지 진단 방법이 연구되고 있으며, 이때 이용하는 변수는 온도와 소음, 진동 그리고 윤활유가 있으며 분석 방법으로는 온도추이분석, 소음분석, 진동분석, 윤활제 분석방법이 주로 이용되고 있다. 본 연구에서는 압연기 베어링의 상태진단의 변수로 베어링의 진동 신호를 선택하고 이 진동신호에서 비선형성이 강한 신호 즉 카오스적 거동이 있음을 타켄스의 매립법과 포엔카레 단면을 이용하여 확인하였다.

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