Analysis on Chaotic Characteristics of Software Project Risk System

Ying Qu,He Wang 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.2

Chaos theory has provided a new pattern for understanding the interacting process of risk factors in system analysis. Software project risk system is a nonlinear system and so it also can be seen as a chaos system. This paper introduces chaos theory into the analysis on software project risk systems to find the evolution law of risk system From the point of chaotic dynamics a dynamic model based on three main parameters for software project risk system on the basis of rational assumption is established. According to judging principles of Lyapunov exponent on chaotic characteristics and the calculation of Lyapunov exponent of software project risk system model, this paper proves that the software project risk system is a chaotic one, which lays the foundations for the related risk research based on the chaos theory. Then it discusses chaotic characteristics such as initial sensibility, inner randomness and strange attractor in software project risk system, which gives guidance for risk control. It also brings a new thought for the study of software project risk management from the point of system.

Spreading Power Spectrum of an Induction Motor Drive System by Chaotic Pulse Width Modulation Method

Kim Jun-Hyeoung,Jung Young-Gook 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5

This paper proposes a chaotic pulse width modulation method to spread the power spectrum of an induction motor drive system. The chaos area λ = 0.99 in the bifurcation tree of the double tent mapping is used for generating the chaotic numbers. An 80C196 micro-controller is employed for generating the chaotic numbers and a triangular carrier with a chaotic frequency is produced using an 80C196 micro-controller and a MAX038 frequency modulator. The experiments are performed with a 1.5[kW] induction motor drive system under a 2.5[A] load condition. The experimental results show that the carrier, voltage/ current and acoustic switching noise spectrum of the proposed method are dispersed over a chaotic frequency range with no specifi c frequency concentration. Especially, in terms of the harmonic spread eff ect of the acoustic switching noise in the frequency range below 10[kHz], we confi rmed that the proposed method shows a slightly smoother distribution in the 5–9[kHz] frequency band than the random PWM (RPWM) method. Finally, the speed control characteristics of the proposed method were investigated by a simple V/F speed control experiment.

Synchronization of Uncertain Chaotic System with Unknown Response System Parameters

Zhanlei Shang,Wenjun Song,Ruiqi Wang,Junwei Lei 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.4

Synchronization of chaotic system is meaningful and widely used in secure communication. A kind of robust adaptive synchronization method was proposed to solve a special chaotic synchronization problem that both response system and driven system have unknown parameters and uncertain nonlinear functions. And the difficulty is also caused by the different structures between master chaotic system and slave chaotic system. A kind of update law of estimation of unknown parameters were designed by choose a proper Lyapunov energy function. And the stability of the whole system is guaranteed by Lyapunov stability theorem. At last, detailed numerical simulation was done to show the rightness of the proposed method.

Intelligent Digital Redesign for Uncertain Nonlinear Systems Using Power Series

성화창(Hwa Chang Sung),박진배(Jin Bae Park),고성현(Sung Hyun Go),주영훈(Young Hoon Joo) 한국지능시스템학회 2005 한국지능시스템학회논문지 Vol.15 No.7

분 논문은 복합 상태 공간에서의 퍼지 기반 제어기를 이용한 지능형 디지털 재설계의 전 역적 접근 방안에 대해 재안하고자 한다. 이산화를 통한 제어기 설계에 있어서 불확실성이 포함된 실시간 비선형 시스템에 대해 보다 효율적이고 안정적인 접근을 위해 TS 퍼지 모델이 사용되었다. 그리고 전 역적 접근을 위핸 방안으로서 문제를 볼록 최적화 관점으로 변환 후, 에라가 가질 수 있는 놈의 영역을 최소화 하여 상태 접합을 이루고자 하였다. 또한 power series를 사용함으로써 불확실성이 포함된 비선형 시스템을 보다 더 정확하게 분석하였다. 샘플링 기간이 충분히 작다면, 불확실 비선형 시스템의 실시간 시스템으로의 전환이 충분한 이유를 가지게 된다. 전 역적 접근을 통한 디지털로 제어된 시스템은 선형 행렬 부등식 형태로 바꾸어 시스템의 안정성을 보장하고자 하였다. 마지막으로 TS 퍼지 모델로 분석된 혼돈 Lorenz system에 적용함으로써 제안된 방법의 안정성과 효율성을 보장받게 된다. This paper presents intelligent digital redesign method of global approach for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent the complex system. And global approach design problems viewed as a convex optimization problem that we minimize the en-or of the norm bounds between nonlinearly interpolated linear operators to be matched. Also, by using the power series, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the global state-matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs). Finally, a TS fuzzy model for the chaotic Lorentz system is used as an example to guarantee the stability and effectiveness of the proposed method.

Backstepping Control and Synchronization for 4-D Lorenz-Stenflo Chaotic System with Single Input

Sung-Hun Yu,Chang-Ho Hyun,Mignon Park 한국지능시스템학회 2011 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.11 No.3

In this paper, a backstepping design is proposed to achieve stabilization and synchronization for the Lorenz-Stenflo (LS) chaotic system. The proposed method is a recursive Lyapunov-based scheme and provides a systematic procedure to design stabilizing controllers. The proposed controller enables stabilization of the chaotic motion and synchronization of two identical LS chaotic systems using only a single control input. Numerical simulations are presented to validate the proposed method.

A study on the Adaptive Controller with Chaotic Dynamic Neural Networks

Sang-Hee Kim,Hee Wook Ahn,Hua O. Wang 한국지능시스템학회 2007 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.7 No.4

This paper presents an adaptive controller using chaotic dynamic neural networks(CDNN) for nonlinear dynamic system. A new dynamic backpropagation learning method of the proposed chaotic dynamic neural networks is developed for efficient learning, and this learning method includes the convergence for improving the stability of chaotic neural networks. The proposed CDNN is applied to the system identification of chaotic system and the adaptive controller. The simulation results show good performances in the identification of Lorenz equation and the adaptive control of nonlinear system, since the CDNN has the fast learning characteristics and the robust adaptability to nonlinear dynamic system.

상호결합 카오스 시스템의 분산 퍼지 동기화

김한솔(Han Sol Kim),주영훈(Young Hoon Joo),박진배(Jin Bae Park) 한국지능시스템학회 2018 한국지능시스템학회논문지 Vol.28 No.2

본 논문에서는 연속 시간 상호 결합 카오스 시스템을 위한 분산 퍼지 동기화 방법을 제안한다. 이를 위해, 구동 (drive)과 응답(response) 카오스 시스템을 각각 연속 시간 상호 결합 타카기-수게노 (Takagi-Sugeno: T-S) 퍼지 모델로 표현하며, 두 시스템의 응답을 동기화하는 분산 퍼지 동기화 제어기의 설계 방법을 선형 행렬 부등식 (linear matrix inequality: LMI) 형태로 유도한다. 또한, 설계 유연성의 증대를 위해 본 논문에서는 구동 카오스 시스템의 상호 결합률을 정확히 알지 못하며, 상한 조건만 알고 있다고 가정한다. 이에 더해, 구동과 응답 카오스 시스템의 소속 함수를 모두 포함하는 새로운 퍼지 리아푸노프 (Lyapunov) 함수를 제안하며, 이를 통해 동기화 조건을 수치적으로 완화한다. 마지막으로, 제안하는 방법의 타당성을 시뮬레이션 예제를 통해 검증한다. In this paper, we propose a decentralized fuzzy synchronization method for continuous-time interconnected chaotic systems. To this end, drive and response chaotic systems are represented as continuous-time interconnected Takagi-Sugeno (T-S) fuzzy model, and its synchronization controller design method is proposed in terms of linear matrix inequalities (LMIs). Also, in order to increase the design flexibility, it is assumed that the interconnection rate of the drive chaotic system is not known exactly but its upper bound condition only can be known. In addition, we define a novel fuzzy Lyapunov function that consists of both membership functions of the drive and response chaotic systems, thereby numerically relaxing the resulting synchronization condition. Finally, the effectiveness of the proposed method is validated through a simulation example.

Intelligent Digital Redesign of Uncertain Nonlinear Systems : Global approach

성화창(Hwachang Sung),주영훈(Younghoon Joo),박진배(Jinbae Park),김도완(Dowan Kim) 한국지능시스템학회 2005 한국지능시스템학회 학술발표 논문집 Vol.15 No.2

This paper presents intelligent digital redesign method of global approach for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent the complex system. And global approach design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between nonlinearly interpolated linear operators to be matched. Also by using the power series, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the global state-matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs). Finally, we prove the effectiveness and stabilization of the proposed intelligent digital redesign method by applying the chaotic Lorentz system.

A study on the Adaptive Controller with Chaotic Dynamic Neural Networks

Kim, Sang-Hee,Ahn, Hee-Wook,Wang, Hua O. Korean Institute of Intelligent Systems 2007 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.7 No.4

This paper presents an adaptive controller using chaotic dynamic neural networks(CDNN) for nonlinear dynamic system. A new dynamic backpropagation learning method of the proposed chaotic dynamic neural networks is developed for efficient learning, and this learning method includes the convergence for improving the stability of chaotic neural networks. The proposed CDNN is applied to the system identification of chaotic system and the adaptive controller. The simulation results show good performances in the identification of Lorenz equation and the adaptive control of nonlinear system, since the CDNN has the fast learning characteristics and the robust adaptability to nonlinear dynamic system.

개별 혼돈 시스템을 이용한 USN 통신 프로토콜 설계

임거수 (Geo-Su Yim) 한국정보전자통신기술학회 2015 한국정보전자통신기술학회논문지 Vol.8 No.6

USN 환경의 구축에 있어서 무선통신을 이용한 안전한 센서 네트워크 구현은 전체 시스템에 있어서 가장 중요한 요소라고 할 수 있다. USN 통신은 접근성, 비접촉성을 높이기 위해 무선통신을 사용하고 있으나 이것으로 인한 보안의 취약성은 시스템을 위험하게 하고 있다. 우리는 이런 다중센서 네트워크인 USN에 효율적으로 적용할 수 있는 보안 프로토콜을 제안한다. 우리가 제안한 프로토콜은 개별 혼돈 시스템을 이용한 방법으로 각각의 센서에 장착된 혼돈 시스템을 주 혼돈 시스템과 미리 준비된 킷값을 초깃값으로 동기화시키고, 동기화된 값을 대칭키로 하여 통신하는 보안 프로토콜이다. 본 논문에서 보인 통신 프로토콜은 USN의 취약한 보안 문제와 센서노드의 프로그램 용량 제한 문제점을 해결하기 위한 새로운 방법으로 계속적인 후속 연구가 이루어진다면 좋은 성과를 얻을 수 있을 것으로 생각된다. In the construction of USN environment, the implementation of a safe sensor network using wireless communications can be said to be the most important factor in the entire system. Although USN communication uses wireless communications to enhance accessability and non-contact capability, this results in the security vulnerability, thus endangering the system. In this regard, we propose a security protocol that can be effectively applied to USN, a multi-sensor network. The proposed protocol is a method using an individual chaotic system, and it is a security protocol to synchronize the main chaotic system mounted on each sensor and prepared key values into the initial values, and to communicate with the use of the synchronized values as symmetric keys. The communication protocol proposed in this paper is expected to yield good results as a new method to resolve security problems of USN and program capacity limitations of sensor nodes if subsequent studies continue to be carried out.