• Journal of the Korea Institute of Information Security & Cryptology
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• v.8 no.3
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• pp.17-26
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• 1998

본 논문에서는 DES(Data EncryptionStandard)시스템에서의 핵심부분에 해당되는f 함수에 대한 비선형 해석을 다룬다. 먼저 S-box의 입출력 형태를 비션형 결합함수 형태로 구성하여 f 함수에 대한 또 다른 형태의 분석방식을 제시한다. 이러한 분석방법은 DES뿐만 아니라 블록 암호시스템의 안전성 문제를 분석할 수 있으며, 또한 보다 안전한 블록암호 시스템을 제안하기 위한 기초자료로 사용될수 있을 것이다.

• Smart Media Journal
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• v.3 no.2
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• pp.9-13
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• 2014

The Levenberg-Marquardt (LM) algorithm is the most widely used fitting algorithm. It outperforms simple gradient descent and other conjugate gradient methods in a wide variety of problems. Based on the work of paper[1], we propose a modified Levenberg-Marquardt algorithm for better performance of mobile system. The LM parameter at the $k_{th}$ iteration is chosen ${\mu}=A{\bullet}{\parallel}f(x){\parallel}{\bullet}I$ where f is the residual function, and J is the Jacobi of f. In this paper, we show this method is more efficient than traditional method under the situation that the system iteration is limited.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.55-64
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• 1990

This paper concerned about a study on the direct pole placement PID self-tuning controller design for DC servo motor control system. The method of a direct pole placement self-tuning PID control for a DC servo motor of Robot manipulator tracks a reference velocity in spite of the parameters uncertainties in nonminimum phase system. In this scheme, the parameters of classical controller are estimated by the recursive least square (RLS)identification algorithm, the pole placement method and diophantine equation. A series of simulation in which minimum phase system and nonminimum phase system are subjected to a pattern of system parameter changes is presented to show some of the features of the proposed control algorithm. The proposed control algorithm which shown are effective for the practical application, and experiments of DC servo motor speed control for Robot manipulator by a microcomputer IBM-PC/AT are performed and the results are well suited.