• Title/Summary/Keyword: bilinear system

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An Efficient Certificateless Public Key Encryption Scheme (인증서 기반이 아닌 효율적인 공개키 암호화 기법)

  • 이영란;이향숙
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.14 no.5
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    • pp.165-176
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    • 2004
  • Al-Riyami and Paterson$^{[1]}$ suggested the new public key paradigm which is called the certificateless public key system. This system takes the advantages of both traditional PKC and ID-based PKC. It does not require the use of certificates of the public key and does not have the key escrow problem caused from the ID-based cryptosystem. In this paper, we propose an efficient certificateless public key encryption scheme which satisfies mutual authentication. The security of our protocol is based on the hardness of two problems; the computational Diffie-Hellman problem(CDHP) and the bilinear Diffie-Hellman problem(BDHP). We also give a formal security model for both confidentiality and unforgeability, and then show that our scheme is probably secure in the random oracle model.

Design of Servo Control System Using Bilinear Transformation Approach (쌍선형 변환법을 이용한 서어보 제어계 설계)

  • Kim, Sang-Bong;An, Hwi-Ung;Ji, Seok-Geun
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.1
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    • pp.81-87
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    • 1990
  • In this paper, a new design method in which transient response behavior of a servo~system can be improved, is proposed using a bilinear transformation method which assigns the poles of the closed-loop system in a specified region. The servo-system is a dynamic system which follows the given reference input automatically. In the above meaning, the design of a servo-system is similar to a regulator design problem for the extended system which is resulted from the given system and the reference input by the well known internal moel principle. In the design problem of servo control system, it is supposed that the proposed design method has more practical meaning in comparison to the other design methods, in the views of assigning the characteristic roots of the closed loop system in a specified region satisfying a design specification for the given transient response rather than in the exact positions of the poles. The applicability of the design method proposed in this paper was proved by the simulation results for the angle control problem of an electrical servo mechanism.

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NUMERICAL SOLUTIONS FOR MODELS OF LINEAR ELASTICITY USING FIRST-ORDER SYSTEM LEAST SQUARES

  • Lee, Chang-Ock
    • Korean Journal of Mathematics
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    • v.7 no.2
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    • pp.245-269
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    • 1999
  • Multigrid method and acceleration by conjugate gradient method for first-order system least squares (FOSLS) using bilinear finite elements are developed for various boundary value problems of planar linear elasticity. They are two-stage algorithms that first solve for the displacement flux variable, then for the displacement itself. This paper focuses on solving for the displacement flux variable only. Numerical results show that the convergence is uniform even as the material becomes nearly incompressible. Computations for convergence factors and discretization errors are included. Heuristic arguments to improve the convergences are discussed as well.

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Optimal Control Design for an Active Control System Considering a Stroke of a Hybrid Mass Damper (복합형 질량 감쇠기의 운동거리를 고려한 능동제어시스템의 최적설계)

  • 고현무
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 1999.04a
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    • pp.196-201
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    • 1999
  • In active control of structures the stroke of a Hybrid Mass Damper is the one of he main constraints of the system because there is limited installation space available in the structure. To design an optimal controller for a HMD system control objective are defined considering these constraints and effectiveness of H-infinity control method with bilinear transform that satisfies the defined objective is examined for the optimum efficiency. Numerical results show that the proposed H-infinity controller satisfies the constraints and provides optimal performance.

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Robust Intelligent Digital Redesign of Nonlinear System with Parametric Uncertainties (불확실성을 갖는 비선형 시스템의 강인한 지능형 디지털 재설계)

  • Sung, Hwa-Chang;Joo, Young-Hoon;Park, Jin-Bae
    • Journal of the Korean Institute of Intelligent Systems
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    • v.16 no.2
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    • pp.138-143
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    • 2006
  • This paper presents intelligent digital redesign method for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent the complex system. And global approach design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between nonlinearly interpolated linear operators to be matched. Also, by using the bilinear and inverse bilinear approximation method, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the global state-matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs). Finally, a TS fuzzy model for the chaotic Lorentz system is used as an . example to guarantee the stability and effectiveness of the proposed method.

Dynamic Analysis of Gimbal Structure System Including Nonlinear Elastic Rubber Vibration Isolator with Shock Acceleration (비선형 탄성 방진 고무부에 충격 가속도를 받는 짐발 구조 시스템의 동적 해석)

  • Lee, Sang Eun;Lee, Tae Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.40 no.4
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    • pp.415-422
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    • 2016
  • When shock acceleration is applied to a mechanical system, it may cause malfunctioning and damage to the system. Hence, to prevent these problems when developing a gimbal structure system for observation reconnaissance, the MIL-STD-810G shock standard must be satisfied as a design specification. Rubber vibration isolators are generally assembled on the base of the system in order to reduce the shock transferred from the aircraft. It is difficult to analyze the transient behavior of the system accurately, because rubber has a nonlinear load-deformation curve. To treat the nonlinear characteristic of the rubber, bilinear approximation was introduced. Using this assumption, transient responses of the system under base shock acceleration were calculated by the finite element method. In addition, experiments with a true prototype were performed using the same conditions as the analytical model. Compared with experimental data, the proposed numerical method is useful for the transient analysis of gimbal structure systems, including rubber vibration isolators with nonlinear stiffness and damping.

Equivalent linear and bounding analyses of bilinear hysteretic isolation systems

  • Wang, Shiang-Jung;Lee, Hsueh-Wen;Yu, Chung-Han;Yang, Cho-Yen;Lin, Wang-Chuen
    • Earthquakes and Structures
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    • v.19 no.5
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    • pp.395-409
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    • 2020
  • With verifications through many relevant researches in the past few decades, adopting the equivalent lateral force procedure for designing seismically isolated structures as a preliminary or even final design approach has become considerably mature and publicly acceptable, especially for seismic isolation systems that mechanically exhibit bilinear hysteretic behavior. During the design procedure, in addition to a given seismic demand, structural designers still need to previously determine three parameters, such as mechanical properties of seismic isolation systems or design parameters and performance indices of seismically isolated structures. However, an arbitrary or improper selection of given parameters might cause diverse or even unacceptable design results, thus troubling structural designers very much. In this study, first, based on the criterion that at least either two design parameters or two performance indices of seismically isolated structures are decided previously, the rationality and applicability of design results obtained from different conditions are examined. Moreover, to consider variations of design parameters of seismically isolated structures attributed to uncertainties of mechanical properties of seismic isolation systems, one of the conditions is adopted to perform bounding analysis for seismic isolation design. The analysis results indicate that with a reasonable equivalent damping ratio designed, considering a specific variation for two design parameters (the effective stiffness and equivalent damping ratio) could present more conservative bounding design results (in terms of isolation displacement and acceleration transmissibility) than considering the same variation but for two mechanical properties (the characteristic strength and post-yield stiffness).

The Lens Aberration Correction Method for Laser Precision Machining in Machine Vision System (머신비전 시스템에서 레이저 정밀 가공을 위한 렌즈 수차 보정 방법)

  • Park, Yang-Jae
    • Journal of Digital Convergence
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    • v.10 no.10
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    • pp.301-306
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    • 2012
  • We propose a method for accurate image acquisition in a machine vision system in the present study. The most important feature is required by the various lenses to implement real and of the same high quality image-forming optical role. The input of the machine vision system, however, is generated due to the aberration of the lens distortion. Transformation defines the relationship between the real-world coordinate system and the image coordinate system to solve these problems, a mapping function that matrix operations by calculating the distance between two coordinates to specify the exact location. Tolerance Focus Lens caused by the lens aberration correction processing to Galvanometer laser precision machining operations can be improved. Aberration of the aspheric lens has a two-dimensional shape of the curve, but the existing lens correction to linear time-consuming calibration methods by examining a large number of points the problem. How to apply the Bilinear interpolation is proposed in order to reduce the machining error that occurs due to the aberration of the lens processing equipment.

Robust Digital Redesign for Observer-based System (관측기 기반 시스템에 대한 강인 디지털 재설계)

  • Sung, Hwa-Chang;Joo, Young-Hoon;Park, Jin-Bae
    • Journal of the Korean Institute of Intelligent Systems
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    • v.17 no.3
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    • pp.285-290
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    • 2007
  • In this paper, we presents robust digital redesign (DR) method for observer-based linear time-invariant (LTI) system. The term of DR involves converting an analog controller into an equivalent digital one by considering two condition: state-matching and stability. The design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between interpolated linear operators to be matched. Also, by using the bilinear and inverse bilinear approximation method, we analyzed the uncertain parts of given observer-based system more precisely, When a sampling period is sufficiently small, the conversion of a analog structured uncertain system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the state-matching of the digitally controlled system are formulated in terms of linear matrix inequalities (LMIs).