• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.3
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• pp.55-62
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• 2000

This paper presents an analysis of the chaotic behavior in the discrete-time voltage mode chaotic generator fabricated using 0.8${\mu}{\textrm}{m}$ single poly CMOS technology. An approximated empirical equation is extracted from the measurement data of a nonlinear function block. Then the bifurcation diagram is simulated according to input variables and Lyapunov exponent λ which represent a dependence on an initial value is calculated. We show the interrelations among time waveforms, state transition, and power spectra for the state condition of chaotic circuit, such as equilibrium, periodic, and chaotic state. And results of experiments in the chaotic circuit with the $\pm$2.5V power supply and sampling clock frequency of 10KHz are shown and compared with the simulated results.

• ETRI Journal
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• v.42 no.4
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• pp.619-632
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• 2020

Highly dispersive S-boxes are desirable in cryptosystems as nonlinear confusion sublayers for resisting modern attacks. For a near optimal cryptosystem resistant to modern cryptanalysis, a highly nonlinear and low differential probability (DP) value is required. We propose a method based on a piecewise linear chaotic map (PWLCM) with optimization conditions. Thus, the linear propagation of information in a cryptosystem appearing as a high DP during differential cryptanalysis of an S-box is minimized. While mapping from the chaotic trajectory to integer domain, a randomness test is performed that justifies the nonlinear behavior of the highly dispersive and nonlinear chaotic S-box. The proposed scheme is vetted using well-established cryptographic performance criteria. The proposed S-box meets the cryptographic performance criteria and further minimizes the differential propagation justified by the low DP value. The suitability of the proposed S-box is also tested using an image encryption algorithm. Results show that the proposed S-box as a confusion component entails a high level of security and improves resistance against all known attacks.

• 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.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.879-889
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• 2003

This research deals with the nonlinearities of rocking vibration associated with impact and sliding on the rocking behavior of rigid block under two dimensional sinusoidal excitation which has different frequencies in two excitation direction. The varied excitation direction influences not only the rocking response but also the sliding motion and the rocking response shape. Chaotic responses are observed in wider excitation amplitude region, when the frequencies in each excitation direction are different. The complex behavior of chaotic response, in the phase space, is related with the trajectory of base excitation and sliding motion.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.9
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• pp.849-855
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• 2010

Damping may change the response characteristics of nonlinear oscillations due to the parametric excitation of a thin cantilever beam. When the natural frequencies of the first bending and torsional modes are of the same order of magnitude, we can observe the one-to-one combination resonance in the perturbation analysis depending on the characteristic parameters. The nonlinear behavior about the combination resonance reveals a chaotic motion depending on the natural frequencies and damping ratio. We can analyze the chaotic dynamics by using the eigenvalue analysis of the perturbed components. In this paper, we derived the equations for autonomous system and solved them to obtain the characteristic equation. The stability analysis was carried out by examining the eigenvalues. Numerical integration gave the physical behavior of each mode for given parameters.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.1
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• pp.8-17
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• 2006

It is essential for robot to have the sensing and communication abilities in the swarm robot system. In general, as the number of robot goes on increasing, the limitation of communication capacity and information overflow occur in global communication system. Therefore a local communication is more effective than global one. In this paper, we analyze information propagation mechanism based on local communication. To find an optimal communication radius, we propose several methods with different conditions. Also, to avoid chaotic behavior which occurs when a robot obtains and loses information, we will suggest the stable condition of information propagation.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.1
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• pp.29-34
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• 2017

Recently, studying chaotic dynamic have been concerned by many researchers in areas of physics, chemistry, mathematics, engineering and social science. Especially, model of addiction, happiness, family and love become major research subjects in the social science. Among these models, love is one of the four emotions that human being have. There are many definitions for love, however, each definitions of love does not coincide with each other. Recently, one of the most important efforts for research is love and it is represented by derivative equation. Then they try to find nonlinear or chaotic behavior from this derivative equation. This paper propose Gaussian fuzzy membership function in order to make external force that are close to action and awareness of human based on love model of Romeo and Juliet with external force. This paper also confirms the existence of nonlinear characteristics through time series and phase portrait.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1040-1053
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• 2002

This research deals with the influence of nonlinearities associated with impact and sliding upon the rocking behavior of a rigid block, which is subjected to two-dimensional horizontal and vertical excitation. Nonlinearities in the vibration were found to depend strongly on the effect of the impact between the block and the base, which involves an abrupt reduction in the system's kinetic energy. In particular, when sliding occurs, the rocking behavior is substantially changed. Response analysis using a non-dimensional rocking equation was carried out for a variety of excitation levels and excitation frequencies. The chaos responses were observed over a wide response region, particularly, in the cases of high vertical displacement and violent sliding motion, and the chaos characteristics appear in the time histories, Poincare maps, power spectra and Lyapunov exponents of the rocking responses. The complex behavior of chaotic response, in phase space, is illustrated by the Poincare map. The distribution of the rocking response is described by bifurcation diagrams and the effects of sliding motion are examined through the several rocking response examples.

• Journal of Mechanical Science and Technology
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• v.17 no.9
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• pp.1249-1260
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• 2003

This present work focuses on the influence of nonlinearities associated with impact on the rocking behavior of a rigid body block subjected to a two-dimensional excitation in the horizontal and vertical directions. The nonlinearities in rocking system are found to be strongly dependent on the impact between the block and the base that abruptly reduces the kinetic energy. In this study, the rocking systems of the two types are considered : The first is an undamped rocking system model that disregards the energy dissipation during the impact and the second is a damped rocking system, which incorporates energy dissipation during the impact. The response analysis is carried out by a numerical method using a non-dimensional rocking equation in which the variations in the excitation levels are considered. Chaos responses are observed over a wide range of parameter values, and particularly in the case of large vertical displacements, the chaotic characteristics are observed in the time histories, Poincare sections, the power spectral density and the largest Lyapunov exponents of the rocking responses. Complex behavior characteristics of rocking responses are illustrated by the Poincare sections.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.67-75
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• 1999

The sensing and communication abilities of a mobile robot are essential to cooperative behavior in distributed autonomous robotic systems. In general, as the number of robot goes on increasing, the limitation of communication capacity and information overflow occur in global communication capacity and information overflow occur in global communication system. Therefore a local communication is more effective than global one. In this paper, we analyze information propagation mechanism based on local communication. To find an optimal communication radius, we propose three methods with different conditions. Also, to avoid chaotic behavior which occurs when a robot obtains and loses information, we find stable condition of information propagation.