• Proceedings of the KSME Conference
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• 2007.05a
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• pp.786-791
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• 2007

Statistical differences between men and women are investigated for a total of eleven joint motions during level walking. Human locomotion which exhibits nonlinear dynamical behaviors is quantified by the chaos analysis. Time series of joint motions was obtained from gait experiments with ten young males and ten young females. Body motions were captured using eight video cameras, and the corresponding angular displacements of the neck and the upper body and lower extremity were computed by motion analysis software. The maximal Lyapunov exponents for eleven joints were calculated from attractors constructed and then were analyzed statistically by one-way ANOVA test to find any difference between the genders. This study shows that sexual differences in joint motions were statistically significant at the shoulder, knee and hip joints.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.05a
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• pp.179-182
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• 2001

인체 활동에 따라 우리 몸에는 다양한 전기적 생체신호가 발생하며 특히 뇌의 활동에 따라 발생되는 뇌파(EEG)는 비침습적 방법으로 측정될 수 있는 장점 때문에 뇌기능 연구 및 임상 등에서 널리 사용되어지고 있다. 또한 임상에서는 주로 뇌 신경계 질환환자의 병인 규명 및 기전 연구를 위하여 뇌파가 사용되어지고 있다. 최근에는 컴퓨터 발달에 따라 카오스, 비선형 이론 등의 다양한 방법으로 복잡한 시계열 신호인 뇌파를 분석하는 기법들이 개발되어 뇌파의 특징점을 찾아 임상에 활용하거나 뇌기능 연구에 적용하려는 연구가 진행되고 있다. 본 논문에서는 잡화(artifact)가 섞여 있는 뇌파신호 및 artifact가 제거된 다음 재구성된 뇌파신호(reconstructed EEG signal), 그리고 독립성분으로 분리된 각각의 신호에 대하여 특징점을 찾기 위하여 비선형 및 선형 분석을 실시하여 유의한 차이점을 밝혔다.

• Journal of The Korean Association For Science Education
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• v.25 no.7
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• pp.711-720
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• 2005

The purpose of this study was to understand mechanisms of scientific discovery and how this can help students, as young scientists, to understand scientific ideas in the science classroom. To unravel this mechanism, this study employed the notion of chaos. This phenomena was rediscovered by Edward Lorenz. In this paper, the general concept of chaos was briefly discussed in relation with previous scientific theories such as Newtonian physics and quantum mechanics. Following this, discovery constraints in terms of available technology at the time was described. In addition, Lorenz's psychological processes during the discovery was also discussed. Based on analysis, major implications for the field of science education were the provision of relevant schemata, the use of cognitive tools, the presentation of problems with various representational forms, and the sharing of ideas with others.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.792-795
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• 2007

To quantify irregular body motions the time series analysis was applied to the gait study. The motions obtained from gait experiment are complex to exhibit nonlinear behaviors. The purpose of this study is to measure quantitatively the characteristics of the major six joints of the body during walking. The gait experiments were carried out for eighteen young males walking on a motor driven treadmill. Joint motions were captured using eight video cameras, and then three dimensional kinematics of the neck and the upper and lower extremities were computed by KWON 3D motion analysis software. The largest Lyapunov exponent was calculated from the time series to quantify stabilities of each joint. The results provides a data set of nonlinear dynamic characteristics for six joints engaged in normal walking.

• Proceedings of the Korean System Dynamics Society
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• 1999.08a
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• pp.133-157
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• 1999

시스템 다이나믹스는 전통적인 단선론적 인과론을 극복하고 시스템의 동태적 특성을 파악하는데 상당한 공헌을 하였다. 그러나 이러한 시스템의 특성을 방정식에 의존하는 시뮬레이션 기법(Equation-Based Simulation:EBS)을 이용하여 분석하는 경우 방정식으로 묘사하기 어려운 복잡적응시스템(Complex Adaptive System)에서는 한계를 갖고 있다. 따라서 시스템의 동태적 특성을 좀더 정확히 파악을 하기 위해서는 시스템을 구성하는 개체(agent)들의 행동이 시스템 전체에 미치는 영향들을 모형화 함으로써 파악하는 것이 바람직하다고 할 수 있다. 본 연구는 이러한 개체지향 시뮬레이션(Agent-eased Simulation: ABS)의 기법을 복잡성과학의 패러다임을 소개함으로써 그 중요성을 설명하고자 한다. 특히 카오스 이론으로부터 복잡성과학으로의 발전 과정을 개념을 중심으로 논의함으로서 복잡적응시스템의 이해를 돕고자 한다. 또한 ABS가 실제로 전통적인 EBS가 묘사하는 생태계 시스템의 변화를 잘 묘사할 수 있다는 사실을 보여주기 위하여 3개체가 있는 Lotka-Voltera 모형을 Cellular Automata 라는 ABS에 기반 한 시뮬레이션 기법을 활용하여 그 사용가능성을 제시하고자 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.12
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• pp.1441-1446
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• 2014

Love which is one of the emotional of mankind, has been studied in sociology and psychology as a matter of grate concern. In this paper we propose a modified romantic behaviors by using basic the love equation of Romeo and Juliet. We represent the behaviors using time series and phase portrait when we vary the parameter in the modified love equation. Also we analyze the behavior's relation by using time series and phase portraits when external force applied as the third person between Romeo and Juliet.

• Journal of the Korean Society of Costume
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• v.38
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• pp.179-191
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• 1998

On this thesis, the focus is that studying costumes which have been affected by deconstructionism that is based on chaos and fractal the-ory. Chaos and fractal theory is accepted as a new paradigm for open world which is changing very vast and fast. And this theory is needed for artists and designers who should have spacetime conciousness and open mind and attitude towark open world. In the results, various costume typess of deconstructionism have been shown by fashion designers and artists' works. Thoes are as follows; 1. normal relationship of costume changes to abnormal relationship 2. three-dimentional structure of costume changes to two-dimentional structure. 3. open to materials and techniques. 4. separated costume parts reconstruct as ambiguous whole on function. 5. body absence and accessorizing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.8
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• pp.889-895
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• 2007

Quantifying dynamic stability is important to assessment of falling risk or functional recovery for leg injured people. Human locomotion is complex and known to exhibit nonlinear dynamical behaviors. The purpose of this study is to quantify major joints of the body using chaos analysis during walking. Time series of the chaotic signals show how gait patterns change over time. The gait experiments were carried out for ten young males walking on a motorized treadmill. Joint motions were captured using eight video cameras, and then three dimensional kinematics of the neck and the upper and lower extremities were computed by KWON 3D motion analysis software. The correlation dimension and the largest Lyapunov exponent were calculated from the time series to quantify stabilities of the joints. This study presents a data set of nonlinear dynamic characteristics for eleven joints engaged in normal level walking.

• Journal of Welding and Joining
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• v.28 no.1
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• pp.72-76
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• 2010

Irregular fluctuation of penetration depth in CW single mode fiber laser welding is analyzed statistically and chaotically. Among various chaos theories, one of the basic concept referred as Lyapunov exponent is applied to the analysis to quantify the irregularity of penetration. Especially, maximal Lyapunov exponent (MLE) is known as the representative value indicating chaotic degree of the system dynamics. MLE calculation method of experimental data is applied to longitudinal spiking defect in fiber laser weld. Laser power modulation is suggested as a remedy then the computed MLE value is compared to CW case. It is shown that the adoption of chaos theory, MLE computation, can be used as a measurement standard to prove the validity of the solutions to prevent the unexpected chaotic behavior of weld through this work.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.4
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• pp.478-485
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• 1999

The purpose of this paper was the determination of the relationship between the chaotic charateristics and various levels of brain activities. Assuming that EEG(eletroencephalogram), which is generated by a nonlinear electiecal behavior of billions of neurons in the brain, has chaotic characteristics, it was confirmed by frequency spectrum analysis, log frequency spectrum analysis, correlation dimension analysis and Lyapunov exponents analysis. Chaotic characteristics are related to the degree of brain activity. The slope of log frequency spectrum increased and the correlation dimension decreased with respect to the brain activities, while the lagrest Lyapunov exponent has some rough correlation.