• 대한간호학회지
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• 제45권1호
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• pp.147-156
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• 2015

Purpose: This study was done to describe the return to work experience of military officers with cancer. Methods: Individual in-depth interviews with 15 participants were conducted between September 2013 and April 2014. Participants were interviewed 1~4 times; interviews continued until the data became saturated. Data were analyzed using Strauss and Corbin's grounded theory. Results: The core category emerged as "living a new life after enduring difficulties". The return to work process consisted of four sequential phases: chaos, positive thought formation, behavior practices, and reformation. Action/interaction strategies used by military officers with cancer to resolve enduring difficulties were controlling emotions, accepting reality, prioritizing health, making efforts to improve relationships, and looking for future jobs. Conclusion: These results will promote understanding of military officers' return to work experience following cancer survival, and will be helpful in developing more effective nursing interventions through enhanced perspectives and insights of practitioners.

• 한국수학교육학회지시리즈A:수학교육
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• 제37권1호
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• pp.115-138
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• 1998

We seek the possibility of introduction of Fractals to the high school math. curriculum through identifying Fractals teaching programs appropriate for the scopes and sequences in math. education for the high school students. We presented the contents of Fractal theory suitable for the high school students. The following subjects were chosen to be introduced; self-similarity, Fractal dimension, Cantor set, Sierpinsky triangle, Sierpinsky carpel Koch curve, Koch island, perimeter estimate of rugged profiles drawn on paper, and chaos game. We developed the working papers and the criteria for appraisal. Each working paper focuses on the activities in which students can solve the given problems, understanding the characteristics and ideas of Fractals. The working papers were given to the second year students who take science course, and the degree of achievements were analyzed based on the appraisal criteria. The results show that it is possible to introduce Fractals to the high school students.

• 전기학회논문지
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• 제61권4호
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• pp.617-621
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• 2012

This paper considers the synchronization problem of chaotic systems. For this problem, the sampled-data control approach is used to achieve asymptotic synchronization of two identical chaotic systems. Based on Lyapunov stability theory, a new stability condition is obtained via linear matrix inequality formulation to find the sampled-data feedback controller which achieves the synchronization between chaotic systems. Finally, the proposed method is applied to a numerical example in order to show the effectiveness of our results.

• Smart Structures and Systems
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• 제14권5호
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• pp.743-763
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• 2014

The paper presents an investigation of the nonlinear dynamical system of an electrostatically actuated micro-cantilever by the incremental harmonic balance (IHB) method. An efficient approach is proposed to tackle the difficulty in expanding the nonlinear terms into truncated Fourier series. With the help of this approach, periodic and multi-periodic solutions are obtained by the IHB method. Numerical examples show that the IHB solutions, provided as many as harmonics are taken into account, are in excellent agreement with numerical results. In addition, an iterative algorithm is suggested to accurately determine period doubling bifurcation points. The route to chaos via period doublings starting from the period-1 or period-3 solution are analyzed according to the Floquet and the Feigenbaum theories.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2521-2525
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• 2005

In this paper, we presented a predictive control technique, which is based on wavelet neural network (WNN), for the control of chaotic systems whose precise mathematical models are not available. The WNN is motivated by both the multilayer feedforward neural network definition and wavelet decomposition. The wavelet theory improves the convergence of neural network. In order to design predictive controller effectively, the WNN is used as the predictor whose parameters are tuned by error between the output of actual plant and the output of WNN. Also the training method for the finding a good WNN model is the Extended Kalman algorithm which updates network parameters to converge to the reference signal during a few iterations. The benefit of EKF training method is that the WNN model can have better accuracy for the unknown plant. Finally, through computer simulations, we confirmed the performance of the proposed control method.

• 대한기계학회논문집B
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• 제29권11호
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• pp.1248-1256
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• 2005

This study was undertaken to investigate the flow characteristics of emulsified fuel with the ultrasonic energy-adding system by using the chaotic method. Efffcts of water contents within emulsified fuel, flow rate and tube length with 5m in diameter from an emulsified chamber has been discussed on the strange attractor and power spectral density function. Five probe sensors were set up from 0.5 to 2.5m by length in 0.5m increments in the tube. In particular, the chaotic features of this system have been practically characterized in terms of chaotic statistics such as the power spectral density function and phase space portraits by resorting to the somewhat noble deterministic chaos theory. In the tube, the dominant frequency increased with increasing water contents and flow rate, but decreased a little with an increase in the length from the emulsified chamber.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.281-284
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• 1995

This paper describes a complexity measure algorithm based on nonlinear dynamics(chaos theory). In order to quantify complexity or regularity of biomedical signal, this paper proposed fractal dimension-1 and fractal dimension-2 algorithm with digital filter. Approximate entropy algorithm which measure a system regularity are also compared. In this paper investigate what we quantify of biomedical signal. These quantified complexity measure may be a useful information about human physiology.

• 한국전자통신학회논문지
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• 제5권5호
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• pp.534-540
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• 2010

본 논문에서는 여러 대의 카오스 로봇이 운영할 때 이들 로봇 사이의 충돌을 회피하고, 또한 장해물을 피해가기 위한 수학적 알고리즘을 제안한다. 포메이션 제어에 위하여, 로봇과 로봇 사이의 통신에 따른 명령체계를 마련하기 위한 기법의 하나로 로봇 시스템들 간의 동기화 기법을 제시하고 컴퓨터 시뮬레이션으로 그 결과를 확인하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2002년도 추계학술발표논문집 (중)
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• pp.1075-1078
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• 2002

스트림 암호 시스템에서는 비선형 결합 LFSR 키 수열을 이용하였다. 주기가 존재하고 상관관계 공격에 약한 비선형 LFSR 키 수열의 문제를 개선하기 위해 제안된 카오스 키 수열은 균형성과 랜덤특성을 만족하지 못하고 있다. 따라서, 본 연구에서는 적응적 임계값 적용 방법을 이용하여 균형성과 랜덤특성을 만족하는 카오스 키 수열 생성 기법을 제안하였다. 본 연구에서 제안한 키 수열 생성 기법은 로지스틱 방정식을 이용하여 키 수열 생성을 위한 카오스 신호를 만든 다음 카오스 신호를 적응적 임계값 적용방법을 통해 '0'과 '1'로 양자화하여 키 수열을 생성한다. 제안한 알고리즘으로 생성된 키 수열의 특징을 분석한 결과 균형성과 랜덤특성이 기존의 카오스 키 수열에 비해 개선되었음을 알 수 있다.

• 음성과학
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• 제9권2호
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• pp.147-155
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• 2002

In the area of speech processing, raw signals used to be presented into 2D format. However, such kind of presentation methods have limitation to extract characteristics from the signal because of the presentation method. Generally, not much information can be detected from the 2D signal. Strange attractor in the field of chaos theory provides a 3D presentation method. In the area of recognition problem, signal presentation method is very important because good features can be detected from a good presentation. This paper discusses a new feature extraction method that extracts features from a cycle of the strange attractor. A neural network is used to check whether the method extracts suitable features or not. The result shows very good points that can be applied to some areas of signal processing.