• 디지털산업정보학회논문지
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• 제7권4호
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• pp.75-79
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• 2011

With the rapid growth of digital communication and the internet, the importance of conducting research on data encryption methods is increasing. Some of the pertinent researches that have been conducted so far introduced data encryption methods using chaos systems, and numerous researches are currently being conducted on such methods. The signals produced by the chaos systems are called "determined noise," and if this is applied to data encryption, very effective results can be obtained. Using the Henon map, the relationship between the non-linearity of the chaos system and the strength of encryption was analyzed, and a linear-structure chaos system that uses non-linearity as a variable for encryption strength was constructed. Using the constructed chaos system, an image was encrypted and decoded, and the correlation coefficient of the linear-structure chaos system's performance was calculated and then analyzed.

• 한국지능시스템학회논문지
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• 제14권7호
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• pp.883-888
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• 2004

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. When a chaos UAVs meet an obstacle in an Arnold equation, Chua's equation and hyper-chaos equation trajectory the obstacle reflects the UAV( Unmanned Aerial Vehicle).

• 천문학논총
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• 제7권1호
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• pp.1-7
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• 1992

We may consider the following three fundamental epistemological questions concerning cosmology. Can cosmology at last understand the origin of the universe? Can computers at last create? Can life be formed at last synthetically? These questions are in some sense related to the liar paradox containing the self-reference and, therefore. may not be answered by recursive processes in finite time. There are, however. various implications such that the chaos may break the trap of the self-reference paradox. In other words, Goedel's incompleteness theorem would not apply to chaos, even if the chaos can be generated by recursive processes. Internal relations among cosmology, epistemology and chaos must be investigated in greater detail.

• Journal of Astronomy and Space Sciences
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• 제38권3호
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• pp.157-164
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• 2021

We describe a method for the in-orbit calibration of body-mounted magnetometers based on the CHAOS-7 geomagnetic field model. The code is designed to find the true calibration parameters autonomously by using only the onboard magnetometer data and the corresponding CHAOS outputs. As the model output and satellite data have different coordinate systems, they are first transformed to a Star Tracker Coordinate (STC). Then, non-linear optimization processes are run to minimize the differences between the CHAOS-7 model and satellite data in the STC. The process finally searches out a suite of calibration parameters that can maximize the model-data agreement. These parameters include the instrument gain, offset, axis orthogonality, and Euler rotation matrices between the magnetometer frame and the STC. To validate the performance of the Python code, we first produce pseudo satellite data by convoluting CHAOS-7 model outputs with a prescribed set of the 'true' calibration parameters. Then, we let the code autonomously undistort the pseudo satellite data through optimization processes, which ultimately track down the initially prescribed calibration parameters. The reconstructed parameters are in good agreement with the prescribed (true) ones, which demonstrates that the code can be used for actual instrument data calibration. This study is performed using Python 3.8.5, NumPy 1.19.2, SciPy 1.6, AstroPy 4.2, SpacePy 0.2.1, and ChaosmagPy 0.5 including the CHAOS-7.6 geomagnetic field model. This code will be utilized for processing NextSat-1 and Small scale magNetospheric and Ionospheric Plasma Experiment (SNIPE) data in the future.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제7권2호
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• pp.87-100
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• 2000

In this paper, we try to approach chasos with numerical method. After investigating nonlinear dynamcis (chaos) theory, we introduce Lyapunov exponent as chaos\`s index. To look into the existence of chaos in 2-dimensional difference equation we computes Lypunov exponent and examine the various behaviors of solutions by difurcation map.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2004년도 추계학술대회 학술발표 논문집 제14권 제2호
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• pp.7-10
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• 2004

In this paper, we propose a method to avoid obstacles that have unstable limit cycles in a chaos trajectory surface. We assume all obstacles in the chaos trajectory surface have a Van der Pol equation with an unstable limit cycle. When a chaos UAVs meet an obstacle in an Arnold equation or Chua's equation trajectory, the obstacle reflects the UAV

• 음성과학
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• 제7권3호
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• pp.167-183
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• 2000

In this paper, we propose two kinds of chaos dimensions, the fuzzy correlation and fuzzy Lyapunov dimensions, for speaker recognition. The proposal is based on the point that chaos enables us to analyze the non-linear information contained in individual's speech signal and to obtain superior discrimination capability. We confirm that the proposed fuzzy chaos dimensions play an important role in enhancing speaker recognition ratio, by absorbing the variations of the reference and test pattern attractors. In order to evaluate the proposed fuzzy chaos dimensions, we suggest speaker recognition using the proposed dimensions. In other words, we investigate the validity of the speaker recognition parameters, by estimating the recognition error according to the discrimination error of an individual speaker from the reference pattern.

• 한국통신학회논문지
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• 제39A권7호
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• pp.365-371
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• 2014

카오스 통신 시스템은 카오스 신호를 이용하여 시스템의 보안성을 향상시킨다. 또한, 도청 확률을 줄일 수 있으며, 간섭 신호나 재밍 신호에 강한 특징을 가진다. 하지만 디지털 통신 시스템보다 BER(Bit Error Rate) 성능이 좋지 않은 단점을 가진다. 이런 이유로 인해 카오스 통신 시스템의 BER 성능을 향상시키기 위한 연구가 활발이 이루어지고 있다. 우리는 이전 연구에서 BER 성능을 향상시키기 위해 새로운 카오스 맵을 제안하고 이 카오스 맵을 'Boss map'이라 불렀다. 또한, 새로운 카오스 송수신기 구조를 제안하여 BER 성능을 향상시켰다. 하지만 BER 성능은 송수신기에서 사용하는 지연 시간에 따라 다르게 평가된다. 따라서 Boss map을 효과적으로 사용하기 위해서는 CDSK(Correlation Delay Shift Keying) 방식과 제안된 카오스 송수신기의 최적의 지연시간을 찾아야 한다. 본 논문에서는 Boss map을 사용했을 때, CDSK 방식과 새로운 송수신기 구조의 지연시간에 따른 BER 성능을 평가한다. 지연 시간에 따른 BER 성능을 평가한 후, CDSK 방식과 새로운 송수신기 구조에서 최적의 BER 성능을 가질 수 있는 지연 시간을 확인한다.

• 전자공학회논문지B
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• 제33B권7호
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• pp.86-98
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• 1996

Modulation and demodualtion circuits of chaos frequency shift keying have been implemented using chua's circuits. The modulatin circuit, which is designed ot perform the frequency-doubling by coupled synchronization wihtout changing the intrinsic characteristics of its two chaos signals generated, modulates the digital input signals. The demodulation circuit detects the digital input signals form carrier by drive synchronization. these circuits, which are simplest until now and have no restriction to their digital input amplitudes, perform the aimed functions.

• 한국과학교육학회지
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• 제25권7호
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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.