• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.446-450
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• 1991

PID controller is popular but have defect inversing following reference input and noise elimination. Therefor, this paper focus on reducing rise time and robustness against noise. The result that is simulated with feedforward method and sliding mode show that rise time decrease and robustness increase.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.171-179
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• 2001

The purpose of this paper is the derivation and development of the new definitions and methods for the new estimation of robustness for the systems having structured uncertainties. This proposition adopts the theoretical analysis of the Lyapunov direct methods, that is, the sign properties of the Lyapunov function derivative integrated along finite intervals of time, in place of the original method of the sign properties of the time derivative of the Lyapunov function itself. This is the new sufficient criteria to relax the stability condition and is used to generate techniques for the robust design of control systems with structured perturbations. The systems considered are assumed to be nominally linear, with time-variant, nonlinear bounded perturbations. This new techniques demonstrate the improvement of robustness bounds from the numerical results.

• Journal of electromagnetic engineering and science
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• v.3 no.1
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• pp.57-61
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• 2003

The effects of high frequency noises on a perturbational inversion technique for a stratified dispersive medium are investigated in this paper. It is shown that the perturbational solution becomes unstable under high frequency noises. The physical origin of this instability is described. In order to enhance the robustness of the perturbational inverse scattering solution, a parametric inversion technique is introduced. The examples for the 2-pole and the 3-pole reflection coefficients are compared and contrasted, and improvement of the robustness of the solutions is shown.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.6
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• pp.606-614
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• 1991

A robust direct adaptive controller with respect to additive and multiplicative unmodeled dynamics is designed. A new term, proportional to the product of the bounded tracking error and normalizing signal, is added to the conventional control input for improvement of robustness and performances of an adaptive system. It is shown by the mathematical analysis and simulation results that the stability of the closed loop system is guaranteed and the performance of the system is improved.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.4
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• pp.298-306
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• 1989

Robustness of adaptive pole-placement control against unmodeled dynamics is proved. This proof is done by showing that the sufficient condition for robustness, conic condition and stability of a specific operator, is satisfied for a larger set of unmodeled dynamics. The simulation results show the proposed method is quite powerful. And the difference between the concept of the pseudoplant control and the known internal model control is shown by the closed loop analysis.

• Journal of Internet Computing and Services
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• v.11 no.5
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• pp.119-126
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• 2010

In this paper, we analyze the robustness of transformed-key asymmetric watermarking system and show its improvement by proposing a new detection method. Based on the assumption that the transformed-key asymmetric watermarking system is under the threat of subtraction attack, we first propose the criterion for the detection performance of the watermarking system and analyze the optimum condition on the system. Next, a new detection method is proposed to improve the detection performance of the system based on the criterion. The proposed improvement makes the system robust to not only subtraction attack but also Wu's attack.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.93-98
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• 2017

This paper relates with the robustness performance improvement of QE-MMA (Quantized Error-MMA) adaptive equalization algorithm based on the dithering in order to reduce the intersymbol interference by nonlinear distortion occurs at channel. The QE-MMA was appeared for the easiness of H/W implementation in place of multiplication to shifting in the tap coefficient updates applying the power-of-two operation to the magnitude of error signal in currently SE-MMA, it's performance were degraded by this. For improving it's performance, the proposed DQE-MMA adds the dither signal which has constant statistical characteristics in the prestage of power-of-two operation. It was confirmed by simulation that the DQE-MMA gives better robustness performance than current QE-MMA in the same channel and signal to noise ratio.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.5
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• pp.997-1008
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• 2022

Today, AI(Artificial Intelligence) technology is being extensively researched in various fields, including the field of malware detection. To introduce AI systems into roles that protect important decisions and resources, it must be a reliable AI model. AI model that dependent on training dataset should be verified to be robust against new attacks. Rather than generating new malware detection, attackers find malware detection that succeed in attacking by mass-producing strains of previously detected malware detection. Most of the attacks, such as adversarial attacks, that lead to misclassification of AI models, are made by slightly modifying past attacks. Robust models that can be defended against these variants is needed, and the Robustness level of the model cannot be evaluated with accuracy and recall, which are widely used as AI evaluation indicators. In this paper, we experiment a framework to evaluate robustness level by generating an adversarial sample based on one of the adversarial attacks, C&W attack, and to improve robustness level through adversarial training. Through experiments based on malware dataset in this study, the limitations and possibilities of the proposed method in the field of malware detection were confirmed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.883-900
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• 2017

In this paper block based blind secure gray image watermarking scheme based on discrete wavelet transform and singular value decomposition is proposed. In devising the proposed scheme, security is given high importance along with other two requirements: robustness and imperceptibility. The use of discrete wavelet transform not only improves robustness but the selection of bands with high tolerance towards noise caused an improvement in terms of imperceptibility. The robustness further improved due to the involvement of singular vectors along with singular values in watermark embedding and extraction process. Finally, to achieve security, the selected DWT band is decomposed into smaller blocks and random blocks are chosen for modification. Furthermore, the elements of left and right singular vectors of selected blocks are chosen based on their dependence upon each other for watermark embedding. Various experiments using different images as host and watermark were conducted to examine and validate the proposed technique. Additionally, the proposed technique is tested against various attacks like compression, affine transformation, cropping, translation, X shearing, scaling, Y shearing, filtering, blurring, different kinds of noises, histogram equalization, rotation, etc. Lastly, the proposed technique is compared with state-of-the-art watermarking techniques and their comparison shows significant improvement of proposed scheme over existing techniques.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.62-65
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• 2004

An optimal robust controller design method for gun driving system is discussed in this paper. The parameters of the gun driving controller are tuned by using the LQR characteristics for the performance and robustness. Tuning method that optimize velocity error gives a significant improvement over the existing PID tuning methods. It is shown that the tuning result of real gun driving system which is regarded as rigidness model or stiffness model satisfy performance and robustness.