• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.977-982
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• 2017

Recently, the effort that converge the sport and ICT continues together with developing ICT. The game is a representative example. The digital sport is developing as mixed type that are composed with sport and digital such as screen golf and screen bowling. The addiction problem exist in the digital sport like the addiction problem exist in general sport. In this paper, we propose the addiction model in the digital sport as fractional-order. We represent time series and phase portrait for nonlinear behavior from proposed fractional-order model and we confirms the difference between them.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.2
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• pp.191-196
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• 2016

Van der Pol's oscillators is non-conservative oscillator that having nonlinear damping phenomena. The energy of its system is dissipative at a high amplitude whereas its system creates the energy at low amplitude. This paper deals with the Van der Pol oscillator model with a fractional order when the external force apply into Van der Pol oscillator. This paper confirms the status of variation for the limit cycle according to the parameter variation of fractional order in the Van der Pol oscillator that can be represented by fractional differential equation.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.6
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• pp.711-717
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• 2014

Happiness has been studied in sociology and psychology as a matter of grave concern. In this paper the happiness model that a new second -order systems can be organized equivalently with a Spring-Damper-Mass are proposed. This model is organized a 2-dimensional model of identically type with Duffing equation. We added a nonlinear term to Duffing equation and also applied Gaussian white noise and period sine wave as external stimulus that is able to cause of happiness. Then we confirm that there are random motion, periodic motion and chaotic motion according to parameter variation in the new happiness model.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.615-621
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• 2014

The Addiction problems have been became a social problem; the social efforts continue to solve these problems. One of those efforts, we need to establish a mathematical modeling for an addictive model to perform analysis of behavior by using this modeling. We need to process the research that can be judged before and after addictive status with result of the behavior analysis. We have to process an observation of transition from before to after addictive status. According to those necessary, this paper proposed the physical exercise model that is composed by novel second order system, which consisted of Spring-Damper-Mass system with equivalence in order to evolve an addictive equation for physical exercise. This paper also is analyzed by the behaviors for those the addictive equation of physical exercise.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.709-716
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• 2011

Recently, there are many difficult for maintenance in the power in established sensor networks. In order to solve this problems, the power development has been interested using vibration in MEMS that insert the MEMS oscillator. In this paper, we propose the MEMS system with Duffing equation to generate vibration signal that can be use power signal in MEMS and confirm and verify the chaotic behaviors in vibration signal of MEMS by computer simulation. As a verification methods, we confirm the existence of period motion and chaotic motion by parameter variation through the time series, phase portrait, power spectrum and poincare map.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.1
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• pp.57-65
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• 2000

In this paper, a model reference adaptive control for the atomic force microscope (AFM) of tapping mode is investigated. The dynamics between the AFM system and al sample is mathematically modeled as a second order spring-mass-damper system with oscillatory inputs. The attractive and repulsive forces between the tip of the AFM system and the sample are derived using the Lennard-Jones potential energy. By non-dimensionalizing the displacement of the tip and the input frequency, the chaotic behavior near a resonance frequency is better depicted through the non-dimensionalized equations. Four nonlinear analysis techniques, a phase portrait, sensitive dependence on initial conditions, a power spectral density function, and a Pomcare map are investigated. Because the equations of motion derived in this paper involve unknown parameter values such as the damping effect of the air and the interaction constants between materials, the standard model reference adaptive control is adopted. Two control objectives, the prevention of chaos and the tracking of reference signal, are pursued. Simulation results are included.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.91-96
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• 2012

Recently, the research of security and its related problems has been received great interested. The research for hper-chaos systems and its synchronization are actively processing as one of method to apply to secure and cryptography communication. In this paper, we propose the synchronization method by coupling coefficient of linear and nonlinear in order to accomplish the synchronization of hyper-chaos system that organized by SC-CNN(State-Controlled Cellular Neural Network). We also verify and confirm the result of synchronization between entire transmitter and receiver, and each subsystem in transmitter and receiver through the phase portrait and difference of time-series by the computer simulation.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.623-637
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• 2019

This paper analyzes the non-stationary vibration and super-harmonic resonances in nonlinear dynamic motion of viscoelastic nano-resonators. For this purpose, a new coupled size-dependent model is developed for a plate-shape nano-resonator made of nonlinear viscoelastic material based on modified coupled stress theory. The virtual work induced by viscous forces obtained in the framework of the Leaderman integral for the size-independent and size-dependent stress tensors. With incorporating the size-dependent potential energy, kinetic energy, and an external excitation force work based on Hamilton's principle, the viscous work equation is balanced. The resulting size-dependent viscoelastically coupled equations are solved using the expansion theory, Galerkin method and the fourth-order Runge-Kutta technique. The Hilbert-Huang transform is performed to examine the effects of the viscoelastic parameter and initial excitation values on the nanosystem free vibration. Furthermore, the secondary resonance due to the super-harmonic motions are examined in the form of frequency response, force response, Poincare map, phase portrait and fast Fourier transforms. The results show that the vibration of viscoelastic nanosystem is non-stationary at higher excitation values unlike the elastic ones. In addition, ignoring the small-size effects shifts the secondary resonance, significantly.

• Korean Journal of Adult Nursing
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• v.28 no.6
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• pp.701-708
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• 2016

Purpose: This study investigated Korean women in between age 30 to 60 who were obese or overweight in order to explore their self-perception based on lifetime phase. Methods: Focus group interviews were performed four times with six to eight participants in each group (a total of 27). Data were analyzed using inductive thematic analysis. Results: The data analysis from the interviews revealed recurring common themes: heavy heart, heavy body, resigned acceptance of their own condition, and compromise. The study also found that each age group had different concerns: concerning others' gaze on their obese appearances (30s), realizing their aging obese appearances (40s), recognizing red flags of their health with obesity (50s), and becoming ambivalent about their obese appearances (60s). Overall, their perceptions of being overweight were negative and stressful. Women in their 30s and 40s were more interested in their appearances, and thus were more obsessive about weight gain. In contrast, women in their 50s and 60s were more accepting of their physical appearances, and thus were more concerned about living healthy than losing weight. Conclusion: These results may be useful to consider when developing tailored weight-control programs for obese and overweight Korean women. Additionally, strategic approaches for successful and effective programs targeting healthy weight should be based on better understanding about women's self-perceptions and motivations.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.383-388
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• 1994

Chaotic analysis of EEG signal responding to auditory stimulus with various carrier frequency and constant triggering frequency is given in this paper. The EEG signal is obtained from the digital 12channel EEG system made in our laboratory. The carrier frequency is varied from 1 kHz to 3 kHz by 0.5 kHz step. Chaos analysis such as pseudo phase space portrait, Lyapunov exponent, and so on is done on the auditory stimulated evoked potential. This result is found to be quite consistent with the well known results from the psychological perception theory.