• Structural Engineering and Mechanics
• /
• 제76권5호
• /
• pp.599-611
• /
• 2020

A state-space method is developed to investigate the time-dependent behaviors of an angle-ply cylindrical shell in cylindrical bending with surface-bonded piezoelectric layers. Both the interfacial diffusion and sliding are considered to describe the properties of the imperfect interfaces. Particularly, a matrix reduction technique is adopted to establish the transfer relations between the elastic and piezoelectric layers of the laminated shell. Very different from our previous paper, in which an approximate numerical technique, i.e. power series expansion method, is used to deal with the time-dependent problems, the exact solutions are derived in the present analysis based on the piezoelasticity equations without any assumptions. Numerical results are finally obtained and the effects of imperfect interfaces on the electro-mechanical responses of the laminated shell are discussed.

• 한국항공우주학회지
• /
• 제36권12호
• /
• pp.1152-1162
• /
• 2008

본 논문은 헬리콥터 비선형 제어기 설계를 위한 State-Dependent Riccati Equation (SDRE) 기법을 다루었다. SDRE 제어기법은 비선형 운동방정식에 대해 선형 시스템과 같은 구조를 갖는 방정식을 필요하기 때문에 State-Dependent Coefficient (SDC) factorization 기법을 개발하여 비선형 운동방정식으로부터 이러한 구조의 방정식을 유도하였다. SDRE제어기를 온라인상에서 설계하는데 필요한 대수 Riccati 방정식의 효율적인 수치해법을 연구하였다. 본 연구에서 제안된 수치기법을 헬리콥터의 경로추종문제로 적용하였으며, 고 신뢰도의 헬리콥터 수학적 모델을 적용하여 실시간으로 SDRE 제어기를 설계할 수 있는 방안을 제안하였다.

• 대한전자공학회논문지
• /
• 제22권6호
• /
• pp.1-6
• /
• 1985

기준입력은 정상상태 오차에 영향을 주는 요인 중의 하나다. 본 논문은 표준입력에 의해 야기피는 정상상태 오차를 제거할 수 있는 새로운 디지날 제각기 설계 방법을 제시한다. 먼저 연준입력 함수 형태에 따라, 기준입력 항이 제거된 새로운 제어 시스템 식이 유도되고. 최려제어를 이용하여 유도된 시스템의 출력을 최소로 하는 제어법칙이 구해진다. 강태공간 방법에 의해. 제시된 제어 알고리즘은 불안정 시스템을 포함해서 시불변 선형 시스템에 적용될 구 있다.

• 한국공간구조학회논문집
• /
• 제19권4호
• /
• pp.69-76
• /
• 2019

A stadium roof that uses the pin-jointed spatial truss system has to be designed by taking into account the unstable phenomenon due to the geometrical non-linearity of the long span. This phenomenon is mainly studied in the single-free-node model (SFN) or double-free-node model (DFN). Unlike the simple SFN model, the more complex DFN model has a higher order of characteristic equations, making analysis of the system's stability complicated. However, various symmetric conditions can allow limited analysis of these problems. Thus, this research looks at the stability of the DFN model which is assumed to be symmetric in shape, and its load and equilibrium state. Its governing system is expressed by nonlinear differential equations to show the double Duffing effect. To investigate the dynamic behavior and characteristics, we normalize the system of the model in terms of space and time. The equilibrium points of the system unloaded or symmetrically loaded are calculated exactly. Furthermore, the stability of these points via the roots of the characteristic equation of a Jacobian matrix are classified.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.134-139
• /
• 2002

This paper presents a servo design method for high track-density hard disk drives, in which the plant time delay, mainly due to the processor computation time, is taken into account. The key idea behind the proposed design method is to incorporate the delay model into the output equation of the state-space representation for the plant model; thereby, the delay is accounted for by a standard state observer in a natural manner, with simplified state equations as compared to those for conventional methods. The results from practical application confirm that the proposed method is quite effective in realizing a high-bandwidth servo system in hard disk drives.

• 수산해양기술연구
• /
• 제11권1호
• /
• pp.26-31
• /
• 1975

Mordern Ocean-going ships utilize stabilization techniques in order to minimize the effects of oscillations due to the unwanted disturbances. In this paper, as an elementary design of automatic control system with linear-state vari;tble feedback and series compensator for ship stabilization, analysis and design is limited to the linear time-invariant single input and output system. In order for the Controlled system to meet the requirements of stability, accuracy and transient response, a model of the automatic control system is proposed. For the analysis and design of this model, the state-space method, that is, the mordern way, or an alternative to the transfer function method of describing a linear system that utilize the state variables and state equations, is applied.

• Journal of applied mathematics & informatics
• /
• 제13권1_2호
• /
• pp.247-259
• /
• 2003

Optimal control problem for the exploitaton of oil is investigated. The optimal control problem under consideration in this paper is governed by weak coupled parabolic PDEs and involves with pointwise state and control constraints. The properties of solution of the state equations and the continuous dependence of state functions on control functions are investigated in a suitable function space; existence of optimal solution of the optimal control problem is also proved.

• 한국전산구조공학회논문집
• /
• 제37권2호
• /
• pp.85-93
• /
• 2024

이 논문에서는 파랑 하중을 받는 부유식 구조체의 운동 해석에 있어서 시스템 식별 방법을 이용한 상태공간방정식 모델을 수립하고 해석하는 방법을 제안하였다. 상태공간방정식 모델의 수립 방법으로는 주파수영역에서 하중-변위 입출력 관계에 대한 목표 전달함수를 구하고 이에 가장 근접하는 상태공간방정식을 구하는 절차를 제시하였다. 전통적으로 부유식 구조체 운동의 시간영역 해석은 지연함수의 합성곱적분을 포함하는 Cummins 방정식을 시간적분하여 이루어진다. 상태공간방정식 모델은 이러한 시간영역해석을 효과적으로 수행하기 위한 방법의 하나로서 연구되어 왔다. 제안하는 방법에서는 시스템 식별방법인 N4SID 와 전달함수의 분모 및 분자 다항식의 계수를 설계변수로 하는 최적화방법을 사용하여 목표 전달함수에 상응하는 상태공간방정식을 구한다. 제안하는 방법의 적용성을 보이는 예제로서 단자유도 수치모델 및 6자유도 바지의 운동을 해석하였다. 제시하는 상태공간방정식 모델은 주파수영역 및 시간영역에서 모두 기존의 해석결과와 잘 일치하고 시간영역해석에서는 계산의 정확도를 확보하면서 계산 시간을 크게 줄일 수 있음을 확인하였다.

• Journal of Astronomy and Space Sciences
• /
• 제32권2호
• /
• pp.151-159
• /
• 2015

The fundamental conception in physics of the propagation of the electromagnetic wave polarization in matter is newly understood as the cardinal keyword in free-space quantum communication technology and cosmology in astrophysics. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has accordingly received attention from scientists exploiting the protocol of quantum key distribution (QKD) to guarantee unconditional security in cryptography communication. We have provided a dynamic polarization platform for presenting the polarization modes of a transverse electromagnetic wave, converting the state of polarization through the arrangement of optical elements, using Jones vectors calculations in Methematica. The platform graphically simulates the mechanism of production and propagation of the polarized waves in a medium while satisfying Maxwell's equations.

• 대한기계학회논문집A
• /
• 제25권1호
• /
• pp.145-152
• /
• 2001

Thermal deformation of a machine tool structure can be evaluated from the analysis of the whole temperature field. However, it is extremely inefficient and impossible to know the whole temperature field by measuring temperatures at every point. So, the temperature estimator is required, which can predict the whole temperature field from the temperatures of just a few points. In this paper, a 1-dimensional heat transfer problem is modeled with modal analysis and state space equations. And then the state observer is designed to estimate the intensity of heat source and the whole temperature field in real time. The reliability of the estimator is verified by making comparison between solutions obtained from the proposed method and the exact solutions of examples. The proposed method is applied to the estimation of temperature distribution in a ball screw system.