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Robust Delay-dependent Stability Criteria for Takagi-Sugeno Fuzzy Systems with Time-varying Delay
Yajuan Liu(유아연),Sangmoon Lee(이상문),Ohmin Kwon(권오민) 대한전기학회 2015 전기학회논문지 Vol.64 No.6
This paper presents the robust stability condition of uncertain Takagi-Sugeno(T-S) fuzzy systems with time-varying delay. New augmented Lyapunov-Krasovskii function is constructed to ensure that the system with time-varying delay is globally asymptotically stable. Also, less conservative delay-dependent stability criteria are obtained by employing some integral inequality, reciprocally convex approach and new delay-partitioning method. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed method.
H<SUB>∞</SUB> Sampled-Data Control of LPV Systems with Time-varying Delay
Yajuan Liu(유아연),Sangmoon Lee(이상문) 대한전기학회 2015 전기학회논문지 Vol.64 No.1
This paper considers the problem of sampled-data control for continuous linear parameter varying (LPV) systems. It is assumed that the sampling periods are arbitrarily varying but bounded. Based on the input delay approach, the sampled-data control LPV system is transformed into a continuous time-delay LPV system. Some less conservative stabilization results represented by LMI (Linear Matrix Inequality) are obtained by using the Lyapunov-Krasovskii functional method and the reciprocally combination approach. The proposed method for the designed gain matrix should guarantee asymptotic stability and a specified level of performance on the closed-loop hybrid system. Numerical examples are presented to demonstrate the effectiveness and the improvement of the proposed method.
Sampled-data Control for Lur'e Dynamical Systems
Yajuan Liu(유아연),Sangmoon Lee(이상문) 대한전기학회 2014 전기학회논문지 Vol.63 No.2
This paper studies the problem of the sampled-data control for Lur"e system with nonlinearities. The nonlinearities are expressed as convex combinations of sector and slope bounds. It is assumed that the sampling periods are arbitrarily varying but bounded. By constructing a new augmented Lyapunov-Krasovskii functional which have an augmented quadratic form with states as well as the nonlinear function, the stabilizing sampled-data controller gains are obtained by solving a set of linear matrix inequalities. The effectiveness of the developed method is demonstrated by numerical simulations.
Yajuan Guan,Josep M. Guerrero,Juan C. Vasquez 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
A coordinated secondary control based on a novel autonomous currents sharing control strategy for balanced discharge rate of energy storage systems in islanded microgrid (MG) is proposed in this paper. The coordinated secondary controller is able to regulate the output power of distributed generating (DG) systems according to their state-of-charge by adjusting the virtual resistances of their voltage controlled inverters. This controller can not only provide the faster response and accurate output current sharing control, but also avoid the potential operation failure resulting from the over current and unintentional outage of DGs. Thus, the stability and reliability of islanded MG can be improved. The eigenvalues and root locus with the proposed controller are presented to design the parameters as well as analyzing the system stability. Simulation results based on Matlab/simulink are presented in order to verify the effectiveness of the proposed controller.
Yajuan Cui,Li Lan,Zhonghua Shi,Shandong Yuan,Yaoqiang Chen,Yi Dan 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.60 No.-
Three ceria-zirconia solid solutions were prepared by different synthesis routes. The results showed that CZ3 exhibited incompact structure with heterogeneous particle size distribution, accompanied by a bimodal pore size distribution. After aging treatment, the specific surface area and cumulative pore volume of CZ3-a were 37 m2/g and 0.22 cm3/g, which decreased by only 51% and 4% respectively from the fresh state. And the particle volume increased by only 4 times. Among the three samples, the textural/structural properties of CZ3 showed the smallest degradation, indicating the highest thermal stability, which was attributed to the incompact structure and special texture.
An Improved Anonymous Remote user Authentication Scheme with Key Agreement based on Dynamic Identity
Yajuan Shi,Han Shen,Yuanyuan Zhang,Jianhua Chen 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.5
To keep the pace with the development of internet technology, remote user authentication techniques become more and more important to protect user’s privacy. Recently, Kumari, et al., presented an improved remote user authentication scheme with key agreement based on dynamic-identity using smart card. This scheme allows legal users to change the password at his will without the need to connect the server. They claimed that their scheme could resist smart card stolen or loss attack, user impersonation and server masquerading attack, and provide user anonymity and untraceability and so on. However, our research indicates that their scheme is completely unsafe. Furthermore, the scheme can’t provide the proper mutual authentication. In this manuscript, we will propose a new scheme, which can withstand those attacks mentioned above and provide the perfect user anonymity and forward secrecy. Security analysis makes it clear that the improved scheme apparently is more secure and practical.
Yajuan Liu(유아연),Sangmoon Lee(이상문) 대한전기학회 2017 전기학회논문지 Vol.66 No.2
This paper studies the state estimation problem for static neural networks with time-varying delay. Unlike other studies, the controller scheme, which involves time-varying sampling and uncertainties, is first employed to design the state estimator for delayed static neural networks. Based on Lyapunov functional approach and linear matrix inequality technique, the non-fragile sampled-data estimator is designed such that the resulting estimation error system is globally asymptotically stable with H∞ performance. Finally, the effectiveness of the developed results is demonstrated by a numerical example.
Novel Results for Global Exponential Stability of Uncertain Systems with Interval Time-varying Delay
Liu, Yajuan,Lee, Sang-Moon,Kwon, Oh-Min,Park, Ju H. The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.6
This paper presents new results on delay-dependent global exponential stability for uncertain linear systems with interval time-varying delay. Based on Lyapunov-Krasovskii functional approach, some novel delay-dependent stability criteria are derived in terms of linear matrix inequalities (LMIs) involving the minimum and maximum delay bounds. By using delay-partitioning method and the lower bound lemma, less conservative results are obtained with fewer decision variables than the existing ones. Numerical examples are given to illustrate the usefulness and effectiveness of the proposed method.
Flirting with the “Modern girl”: Socialism and cosmopolitanism in packaging a model-laborer in China
Liu Yajuan,Galway Matt,Hoy Thomas 이화여자대학교 아시아여성학센터 2022 Asian Journal of Women's Studies(AJWS) Vol.28 No.3
Huang Baomei was not an average national model-laborer (laomo). The Chinese Communist Party (CCP) granted her this grand title to leverage her social status for promoting its goals of getting workers to work harder, produce more, and consume less. But Huang Baomei longed to look and act like a “modern girl” (modeng nülang), the well-dressed and well-groomed image which Shanghai women had aspired to over generations. She not only survived through political movements such as the Anti-Rightist Campaign, but also took advantage of the movement discourse to win the hearts of many. She faced tough opposition, but the CCP Shanghai Municipal Committee helped to elevate her popularity over more than a decade in Communist China. In examining her career, this paper shows how Huang introduced debates among CCP cadres and both reshaped and directed key concepts in CCP propaganda at local and national levels