• Title, Summary, Keyword: 카오스

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카오스, 복잡계와 경제학

  • 김승환
    • Journal of the KSME
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    • v.42 no.4
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    • pp.46-49
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    • 2002
  • 최근 카오스, 프랙탈 등 과학적 방법론이 국내에서도 금융공학에 접목되고 있으며, 시장경제 이해와 과학적 투자 기법을 통한 금융시장의 선진화에 공헌할 것으로 기대되고 있다.

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저자 초대-"축제의 정신" 펴낸 이상일 교수

  • Park, Cheon-Hong
    • The Korean Publising Journal, Monthly
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    • pp.12-12
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    • 1998
  • 축제는 카오스와 난장을 통해 인간의 근원적 활력을 되찾게 합니다. 카오스 후의 생기는 일상의 삶을 고갈시키지 않는 싱싱한 수맥이지요. 오늘날 우리의 민속축제는 과거의 형식만 남아 있고, 상품광고나 스폰서의 잔치마당으로 타락했습니다. 현재를 반영하는 삶의 축제가 이 시대 이 땅의 축제로 자리매김될 수 있어야 합니다.

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BER Performance Evaluation of Boss Map According to Delay Time in CDSK Modulation Scheme and Chaos Transceiver (CDSK 변조 방식과 카오스 송수신기의 지연시간에 따른 Boss Map의 BER 성능 평가)

  • Lee, Jun-Hyun;Keum, Hong-Sik;Lee, Dong-Hyung;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.7
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    • pp.365-371
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    • 2014
  • Chaos communication system is possible to improve the system security by using chaos signal. Further, it is possible to reduce the possibility of eavesdropping, and have strong characteristics from interference signal and jamming signal. However, BER(Bit Error Rate) performance of chaos system is worse than digital communication system. By this reason, researches in order to improve the BER performance of chaos communication system are being actively studied. In previous studies, we proposed a novel chaos map for BER performance improvement, and called it 'Boss map'. Also, we proposed a novel chaos transceiver for BER performance improvement. However, BER performance is evaluated differently according to delay time in transceiver. Therefore, in order to use Boss map effectively, we should find the optimal delay time in proposed chaos transceiver. In this paper, when Boss map is used, we evaluate BER performance of CDSK(Correlation Delay Shift Keying) system and novel chaos transceiver according to delay time. After evaluation of BER performance according to delay time, we find a delay time that is possible to have best BER performance in CDSK system and novel chaos transceiver.

Characteristic Analysis of Proposed Chaos Map in CDSK System (CDSK 변조 방식에서 제안한 카오스 맵의 특성 분석)

  • Lee, Jun-Hyun;Ryu, Heung-Gyoon
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.5
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    • pp.44-50
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    • 2014
  • Chaos communication system is one of the security algorithms that is applied to improve the security. Chaos signal is non-linear, and it is generated randomly according to the initial conditions. Also, chaos communication system has characteristics such as non-periodic, wide-band, non-predictability of signals and easy implementation. So, security of chaos communication system is superior, and it has low interception probability and good anti-jamming characteristic. However, BER performance is worse than digital communication system, because it has many self interference signal in case of CDSK system. To improve these disadvantages, we analyze the PDF trend which can improve the BER performance in existing study, and we proposed a chaos map. And, proposed chaos map was defined as the 'Boss map'. Generally, BER performance is changed according to initial values, parameters and spreading factors. Therefore, in this paper, we will introduce PDF trends which can improve the BER performance, and will describe about Boss map. Also, characteristics of Boss map is analyzed by evaluating the BER performance of Boss map according to initial values, parameters and spreading factors. As a result, while maintaining the similar BER performance, initial value of Boss map can be selected from 0 to 1.2, and BER performance is best when parameter alpha is 2.5. Also, BER performance is best when spreading factor is 50.

A Novel Transmitter and Receiver Design of CDSK-Based Chaos Communication System (CDSK 방식의 카오스 통신 시스템의 새로운 송·수신기 설계)

  • Lee, Jun-Hyun;Ryu, Heung-Gyoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.10
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    • pp.987-993
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    • 2013
  • Chaos communication system has characteristics of non-periodic, non-predictability, broadband signal and easy implementation. Also, chaos communication system is sensitive to the initial value, because completely another signal is generated when initial value of chaos equation is changed subtly. By these characteristics, security of chaos communication system is generally evaluated better than other digital communication systems. However, BER(Bit Error Rate) performance is worse than other digital communication systems, because transmitter and receiver of existing chaos communication system are strongly influenced by reference signal and noise. So, studies in order to improve the BER performance of chaos communication system is continuously performed. In this paper, We will propose a new CDSK (Correlation Delay Shift Keying) receiver in order to improve the BER performance. After we compare to the performance of existing receiver and proposed receiver, BER performance of proposed receiver evaluate. A novel receiver has characteristic that BER performance is better than existing receiver. However, if existing transmitter is used, existing receiver is possible to recover information bits even though BER performance is bad. Therefore, we propose a novel CDSK transmitter in order to improve the security of proposed receiver. When information bits are transmitted by using proposed transmitter, existing receiver is impossible to recover information bits, and proposed receiver is possible to recover information bits.

Chaotic Disaggregation of Daily Rainfall Time Series (카오스를 이용한 일 강우자료의 시간적 분해)

  • Kyoung, Min-Soo;Sivakumar, Bellie;Kim, Hung-Soo;Kim, Byung-Sik
    • Journal of Korea Water Resources Association
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    • v.41 no.9
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    • pp.959-967
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    • 2008
  • Disaggregation techniques are widely used to transform observed daily rainfall values into hourly ones, which serve as important inputs for flood forecasting purposes. However, an important limitation with most of the existing disaggregation techniques is that they treat the rainfall process as a realization of a stochastic process, thus raising questions on the lack of connection between the structure of the models on one hand and the underlying physics of the rainfall process on the other. The present study introduces a nonlinear deterministic (and specifically chaotic) framework to study the dynamic characteristics of rainfall distributions across different temporal scales (i.e. weights between scales), and thus the possibility of rainfall disaggregation. Rainfall data from the Seoul station (recorded by the Korea Meteorological Administration) are considered for the present investigation, and weights between only successively doubled resolutions (i.e., 24-hr to 12-hr, 12-hr to 6-hr, 6-hr to 3-hr) are analyzed. The correlation dimension method is employed to investigate the presence of chaotic behavior in the time series of weights, and a local approximation technique is employed for rainfall disaggregation. The results indicate the presence of chaotic behavior in the dynamics of weights between the successively doubled scales studied. The modeled (disaggregated) rainfall values are found to be in good agreement with the observed ones in their overall matching (e.g. correlation coefficient and low mean square error). While the general trend (rainfall amount and time of occurrence) is clearly captured, an underestimation of the maximum values are found.

Secure Communication in Hyper-Chaos Circuit (하이퍼 카오스 회로에서의 카오스 비밀통신)

  • Bae, Young-Chul
    • Proceedings of the KIEE Conference
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    • pp.2072-2074
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    • 2001
  • In this paper, a transmitter and a receiver using two identical Hyper-Chaos that n-double scroll circuits are proposed and a hyper-chaos synchronizations and secure communication are investigated. we are proposed unidirectional coupling of identical n-double scroll cell for hyper-chaos synchronization. We've shown that simulation result is synchronization and secure communication.

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Synchronization in Hyper-Chaos Circuit (하이퍼카오스 회로에서의 카오스 동기화)

  • Bae, Young-Chul
    • Proceedings of the KIEE Conference
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    • pp.2069-2071
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    • 2001
  • In this paper, a transmitter and a receiver using two identical Hyper-Chaos that n-double scroll circuits are proposed and a hyper-chaos synchronizations are investigated. we are proposed unidirectional coupling of ide n-double scroll cell for hyper-chaos synchronizat. We've shown that simulation result is synchronization.

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카오스 이론과 유체혼합 - 3차원 혼합의 적용예를 중심으로 -

  • 황욱렬;권태헌
    • Journal of the KSME
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    • v.42 no.4
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    • pp.42-45
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    • 2002
  • 이 글에서는 카오스의 이론적인 관점에서 성공적이라 할 수 있는 3차원 유동의 적용 예 중에서 산업적으로 관심의 대상이 될 수 있는 파이프 유동에서의 혼합증진, 혼합탱크 내의 혼합증진, 단축압출기에서의 혼합증진, 그리고 마이크로 채널 유동에서의 혼합증진 등 네 가지 유동에 대해 소개하도록 한다.

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