• Structural Engineering and Mechanics
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• 제44권2호
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• pp.219-238
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• 2012

Objective of this paper is to compare linear buckling analysis formulations, available in commercial finite element programs. Modern steel design codes, including Eurocode 3, make abundant use of linear buckling loads for calculation of slenderness, and of linear buckling modes, used as shapes of imperfections for nonlinear analyses. Experience has shown that the buckling mode shapes and the magnitude of buckling loads may differ, sometimes significantly, from one algorithm to another. Thus, three characteristic examples have been used in order to assess the linear buckling formulations available in the finite element programs ADINA and ABAQUS. Useful conclusions are drawn for selecting the appropriate algorithm and the proper reference load in order to obtain either the classical linear buckling load or a good approximation of the actual geometrically nonlinear buckling load.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.827-829
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• 1999

The identification of nonlinear system using Extended GMDH(EGMDH) is studied in this paper. The proposed EGMDH algorithm is based on GMDH(Group Method of Data handling) method and its structure is similar to Neural Networks. The each node of EGMDH structure utilizes several types of high-order polynomial such as linear, quadratic and cubic, and is connected as various kinds of multi-variable inputs. As the operating condition changes, the parameters of EGMDH will also change, so the proposed scheme by means of the EGMDH method is capable of adapting rapidly to the changing environment. The simulation result shows that the simple nonlinear process can be modeled reasonably well by the proposed method which are simple but efficient.

• 한국통신학회논문지
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• 제21권4호
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• pp.807-821
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• 1996

In this paper, we proposed a nonlinear hierarchical mtion estimation method. Generally, the conventional hierarchical motion estimation methods have been proposed for fast convergence and detection of large motions. But they have a common drawback that large error in motion estimation is propapated across motion discontinuities. This artifiact is due to the constriaint of motion continuity and the linear interpolation of motion vectors between hierarchical levels. In this paper, we propose an effective hierarchical motion estimation mechod that is robust to motion discontinuities. The proposed algorithm is based on the decomposition of the functional domain for optimizing the intra-level motion estimation functional. Also, we propose an inter-level nonlinear motion estimation equation rather than using the conventional linearprojection scheme of motion field. computer simulations with several test sequences show tht the proposed algorithm performs better than several conventional methods.

• International Journal of Control, Automation, and Systems
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• 제1권2호
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• pp.215-221
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• 2003

The education system in this paper is used to demonstrate and educate the effects of electromagnetic induction. Placing an aluminum ring over the core and switching on AC source causes the ring to jump in the air due to induced currents in the ring producing a magnetic field opposed to that produced in the core. To control the position of the ring by only the current, it is to require nonlinear control algorithm and control board that is composed of photo sensors, decode circuit, computer communication, and power electronics circuit. This paper provides the development for education system in detail and the effects of dynamic neural networks for nonlinear control with on line is studied.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.431-435
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• 2001

The active structural control has emerged as structural safety of structures against natural loadings such as earthquake and wind loadings. Of many control algorithms, Sliding-Mode Control (SMC) can design both linear controller and nonlinear controller. The robustness against parameter variations as well as excitation uncertainties that is imparted to the SMC due to its nonlinear control action, could make SMC an attractive control algorithm when dealing with structures where the external excitation constitutes the main uncertainty in the system. This paper demonstrates experimentally the efficacy of the SMC algorithm based on the active mass driver system in reducing the response of seismically excited buildings. The SMC control strategy is verified with the experimental study on the one-story building model equipped with the active mass driver.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1212-1220
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• 2015

This article presents a new nonlinear joint (state and parameter) estimation algorithm based on fusion of Kalman filter and randomized unscented Kalman filter (UKF), called Kalman randomized joint UKF (KR-JUKF). It is assumed that the measurement equation is linear. The KRJUKF is suitable for time varying and severe nonlinear dynamics and does not have any systematic error. Finally, joint-EKF, dual-EKF, joint-UKF and KR-JUKF are applied to a CSTR with cooling jacket, in which production of propylene glycol happens and performance of KR-JUKF is evaluated.

• Smart Structures and Systems
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• 제19권4호
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• pp.403-413
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• 2017

The present article encompasses a nonlinear finite element (FE) and genetic algorithm (GA) based optimal vibration energy harvesting from nonprismatic piezo-laminated cantilever beams. Three cases of cross section profiles (such as linear, parabolic and cubic) are modelled to analyse the geometric nonlinear effects on the output responses such as displacement, voltage, and power. The simultaneous effects of taper ratios (such as breadth and height taper) on the output power are also studied. The FE based nonlinear dynamic equation of motion has been solved by an implicit integration method (i.e., Newmark method in conjunction with the Newton-Raphson method). Besides this, a real coded GA based constrained optimization scheme has also been proposed to determine the best set of design variables for optimal harvesting of power within the safe limits of beam stress and PZT breakdown voltage.

• 대한기계학회논문집B
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• 제26권7호
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• pp.959-965
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• 2002

It is intended to develop an algorithm for dynamic simulation of a fast-acting solenoid valve. The coupled equations of electric, magnetic, and mechanical systems should be solved simultaneously in a transient nonlinear manner. The transient nonlinear electromagnetic field is analyzed by the Finite Element Method (FEM), which is coupled with nonlinear electronic circuitry. The dynamic movement of the solenoid valve is analyzed at every time step from the force balance acting on the plunger, which includes the electromagnetic force calculated from the Finite Element analysis as well as the elastic force by a spring and the hydrodynamic pressure force along the flow passage. Dynamic responses of the solenoid valves predicted by this algorithm agree well with the experimental results including bouncing effects.

• 한국지능시스템학회논문지
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• 제7권3호
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• pp.65-71
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• 1997

신경 회로망의 출현으로 비선형 시스템 모델링에 대한 관힘이 다시 고조되고 있다. 따라서 본 논문에서는 미지의 비선형 시스템을 동적으로 인식하기 위해 GMDH(Group Method of Data Handling) 일고리즘을 사용한 DPNN(Dynamic Polynomial Neural Network)을 제안한다. GMDH를 사용한 동적 시스템의 인신은 일렬의 입/출력 데이타를 인가하여 필요한 계수들의 집합을 동적으로 산출함으로써 훈련시킨다. 또한 DPNN을 이용하여 비선형 시스템을 제어하기 위해, MRA(Model Reference Adaptive Control)를 설계한다. 결과에서 컴퓨터 시뮬레이션을 통해 DPNN을 사용한 모델링과 제어가 잘 수행됨을 알 수 있었다.

• 한국지능시스템학회논문지
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• 제8권3호
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• pp.50-55
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• 1998

GMDH(Group Method of Data Handing)는 복잡한 비선형 시스템을 인식하는데 유용한 데이타 분석 기법이다. 따라서 본 논문에서는 비선형 다이내믹 시스템을 모델링하기 위한 GMDH 알고리즘의 적용 방법을 제안한다. GMDH를 사용한 다이내믹 시스템의 인식은 일련의 입출력 데이타를 인가하여 필요한 계수들의 집합을 동적으로 산출함으로써 이루어진다. 또한, 본 논문에서는 데이타를 취사 선택하는 기준을 순차적으로 감소시킴으로써 GMDH의 단점인 계산량의 과다를 방지하는 방법도 제안하였다.