• Title/Summary/Keyword: 시스템 섭동

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Introduction of Numerical Simulation Techniques for High-Frequency Combustion Instabilities (고주파 연소불안정 예측을 위한 해석기술 개발 사례)

  • Kim, Seong-Ku;Joh, Miok;Han, Sanghoon;Choi, Hwan-Seok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2017.05a
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    • pp.68-77
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    • 2017
  • High-frequency combustion instability results from a feedback coupling between the unsteady heat release rate and the acoustic waves formed resonantly in the combustion chamber. It can be modeled as thermoacoustic problems with various degrees of the assumptions and simplifications. This paper presents numerical analysis of self-excited combustion instabilities in a variable-length lean-premixed combustor and designs of passive control devices such as baffle and acoustic resonators in a framework of 3-D FEM Helmholtz solver. Nonlinear behaviors such as steep-fronted shock waves and a finite amplitude limit cycle are also investigated with a compressible flow simulation technique.

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DYNAMIC MODEL DEVELOPMENT FOR INTERPLANETARY NAVIGATION (행성탐사 항행해 결정을 위한 동역학 모델 개발)

  • Park, Eun-Seo;Song, Young-Joo;Yoo, Sung-Moon;Park, Sang-Young;Choi, Kyu-Hong;Yoon, Jae-Cheol;Yim, Jo-Ryeong;Choi, Joon-Min;Kim, Byung-Kyo
    • Journal of Astronomy and Space Sciences
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    • v.22 no.4
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    • pp.463-472
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    • 2005
  • In this paper, the dynamic model development for interplanetary navigation has been discussed. The Cowell method for special perturbation theories was employed to develop an interplanetary trajectory propagator including the perturbations due to geopotential, the Earth's dynamic polar motion, the gravity of the Sun, the Moon and the other planets in the solar system, the relativistic effect of the Sun, solar radiation pressure, and atmospheric drag. The equations of motion in dynamic model were numerically integrated using Adams-Cowell 11th order predictor-corrector method. To compare the influences of each perturbation, trajectory propagation was performed using initial transfer orbit elements of the Mars Express mission launched in 2003, because it can be the criterion to choose proper perturbation models for navigation upon required accuracy. To investigate the performance of dynamic model developed, it was tested whether the spacecraft can reach the Mars. The interplanetary navigation tool developed in this study demonstrated the spacecraft entering the Mars SOI(Sphere of Influence) and its velocity .elative to the Mars was less than the escape velocity of the Mars, hence, the spacecraft can arrive at the target planet. The obtained results were also verified by using the AGI Satellite Tool Kit. It is concluded that the developed program is suitable for supporting interplanetary spacecraft mission for a future Korean Mars mission.

Disturbance Observer of Multi-Input Multi-Output Linear Systems (다중입출력 선형 시스템에서의 외란 관측기 설계)

  • Joo, Young-Jun;Back, Ju-Hoon;Shim, Hyung-Bo;Seo, Jin-Heon
    • Proceedings of the KIEE Conference
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    • 2007.10a
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    • pp.51-52
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    • 2007
  • 이 논문에서는 다중입출력 선형 시스템에 대한 외란 관측기설계 방법을 제안하고자 한다. 제안된 방법을 특이 섭동(Singular Perturbation) 이론을 사용하여 해석하며, 그 결과 Q 필터의 상수가 매우 작다면 외란 제거와 시스템 불확실성에 대한 보상을 통하여 실제 시스템을 공칭 시스템으로 근사화 시켜주는 것을 볼 수 있다.

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Decentralized Dynamic Controller Design for Uncertain Large-Scale Systems (섭동을 가지는 대규모 시스템의 다이나믹 제어기 설계)

  • Park, J.H.;Won, S.
    • Proceedings of the KIEE Conference
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    • 1999.11c
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    • pp.469-471
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    • 1999
  • In this paper, a dynamic output feedback controller design technique for robust decentralized stabilization of uncertain large-scale systems is presented. Based on the Lyapunov method, a sufficient condition for robust stability, is derived in terms of three linear matrix inequalities(LMIs). The solutions of the LMIs can be easily obtained using efficient convex optimization techniques.

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Stabilizing controller for singularly perturbed discrete time systems (특이섭동 쌍일차 이산시 시스템에서의 안정화 제어에 관한 연구)

  • Kim, Beom-Soo;Kim, Young-Joong;Chang, Sae-Kwon;Lim, Myo-Taeg
    • Proceedings of the KIEE Conference
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    • 2002.07d
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    • pp.2155-2157
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    • 2002
  • In this paper, we present a stabilizing controller for the singularly perturbed discrete time bilinear systems. The proposed control method guarantees the robust stability for the resulting closed loop system with multi-input. We verify the proposed algorithm by a numerical example.

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Application of H¡? Controller Design Method to a Linear Singularly Perturbed System (H$\infty$ 제어기 설계법의 선형 특이섭동 시스템에의 적용)

  • Yoo, Seog-Hwan
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.43 no.4
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    • pp.648-657
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    • 1994
  • This paper presents a solution of the H$\infty$ control problem for a linear singularly perturbed system. A sufficient condition for a linear singularly perturbed system to achieve the prescribed disturbance attenuation level is obtained. Based upon this sufficient condition, an H$\infty$ controller design method which involves the solutions of two generalized algebraic Riccati equations(GRE) is developed.

Delay-Dependent Criterion for Stability of Uncertain Neutral Systems (비선형 섭동을 갖는 뉴트럴 시스템의 시간종속 안정성 조건식)

  • Park, Ju-H.
    • Proceedings of the KIEE Conference
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    • 2000.07d
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    • pp.2320-2322
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    • 2000
  • In this paper, the problem of the stability analysis for linear neutral delay-differential systems with nonlinear perturbations is investigated. Using Lyapunov second method, a new delay-dependent sufficient condition for asymptotic stability of the systems in terms of linear matrix inequalities (LMIs), which can be easily solved by various convex optimization algorithms, is presented. A numerical example is given to illustrate the proposed method.

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Structural System Identification using adaptive design domain approach (적응성 설계영역 기법을 이용한 구조 시스템 식별)

  • Jang, Seong-Min;Baek, Sung-Min;Cho, Meang-Hyo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2009.04a
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    • pp.146-150
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    • 2009
  • 구조 시스템 식별은 역문제로서 이상화된 유한요소 모델을 실험치와 일치시키기 위해 유한요소모델을 보정하는 형태로 주로 이루어진다. 이를 위해 비선형 섭동법이 사용되고 있으며 이 방법을 실제 문제에 사용하기 위해서 시스템 축소법에 대한 연구가 진행 되고 있다. 하지만 기존의 방법에서는 유한요소모델의 모든 요소가 실험치와 다르다고 가정하여서 전체 요소 수만큼의 설계 변수를 두어서 역해석을 수행한다. 이런 기존의 방법에서는 시스템이 커짐에 따라 연산 시간이 기하급수적으로 증가하게 되어 어려움이 있다. 설계 변수의 증가는 해공간(solution space)의 확장을 의미하며 이는 해의 정확성에 큰 영향을 끼친다. 본 연구에서는 모델을 적은 수의 설계영역으로 나누어서 반복연산 단계마다 해의 경향성을 이용해서 설계 영역을 전략적으로 변경하는 적응성 설계영역기법을 제안한다. 수치예제를 통해 본 연구에서 제안하는 기법의 정확도와 효용성을 고찰한다.

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Robust Decentralized Stabilization of Uncertain Large-Scale Discrete-Time Systems with Delays (시간지연을 갖는 이산시간 대규모 시스템의 강인 제어기 설계)

  • Park, Ju-Hyeon
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.37 no.6
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    • pp.7-14
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    • 2000
  • This paper describes the synthesis of robust decentralized controllers for uncertain large-scale discrete-time systems with time-delays in subsystem interconnections. Based on the Lyapunov method, a sufficient condition for robust stability, is derived in terms of a linear matrix inequality (LMI). The solutions of the LMI can be easily obtained using various efficient convex optimization techniques. A numerical example is given to illustrate the proposed method.

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Wavelet-based Analysis for Singularly Perturbed Linear Systems Via Decomposition Method (웨이블릿 및 시스템 분할을 이용한 특이섭동 선형 시스템 해석)

  • Kim, Beom-Soo;Shim, Il-Joo
    • Journal of Institute of Control, Robotics and Systems
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    • v.14 no.12
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    • pp.1270-1277
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    • 2008
  • A Haar wavelet based numerical method for solving singularly perturbed linear time invariant system is presented in this paper. The reduced pure slow and pure fast subsystems are obtained by decoupling the singularly perturbed system and differential matrix equations are converted into algebraic Sylvester matrix equations via Haar wavelet technique. The operational matrix of integration and its inverse matrix are utilized to reduce the computational time to the solution of algebraic matrix equations. Finally a numerical example is given to demonstrate the validity and applicability of the proposed method.