• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.464-471
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• 2013

This paper proposes a hybrid searching algorithm based on parameter identification for power system load models. Hybrid searching was performed by the combination of particle swarm optimization (PSO) and a complex method, which enhances the convergence of solutions closer to minima and takes advantage of global searching with PSO. In this paper, the load model of interest is composed of a ZIP model and a third-order model for induction motors for stability analysis, and parameter sets are obtained that best-fit the output measurement data using the hybrid search. The origin of the hybrid method is to further apply the complex method as a local search for finding better solutions using the selected particles from the performed PSO procedure.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권2호
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• pp.160-164
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• 2010

The radio frequency (RF) model of SOI FinFETs with gate length of 40 nm is verified by using a 3-dimensional (3-D) device simulator. This paper shows the equivalent circuit model which can be used in the circuit analysis simulator. The RMS modeling error of Y-parameter was calculated to be only 0.3 %.

• Structural Engineering and Mechanics
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• 제5권3호
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• pp.221-237
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• 1997

This paper presents a new uniaxial material model for rate-sensitive analysis addressing both the transient and steady-state responses. The new model adopts visco-plastic theory for the rate-sensitive response, and employs a three-parameter representation of the overstress as a function of the strain-rate. The third parameter is introduced in the new model to control its transient response characteristics, and to provide flexibility in fitting test data on the variation of overstress with strain-rate. Since the governing visco-plastic differential equation cannot be integrated analytically due to its inherent nonlinearity, a new single-step numerical integration procedure is proposed, which leads to high levels of accuracy almost independent of the size of the integration time-step. The new model is implemented within the nonlinear analysis program ADAPTIC, which is used to provide several verification examples and comparison with other experimental and numerical results. The companion paper extends the three-parameter model to trilinear static stress-strain relationships for steel and concrete, and presents application examples of the proposed models.

• 대한전기학회논문지:전력기술부문A
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• 제51권3호
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• pp.118-126
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• 2002

AVR parameter tuning for voltage control of generators has generally been done with the off-line open-circuit model of the synchronous generator. When the generator is connected on-line and operating with load the AVR operates in an entirely different environment from the open-circuit conditions. This paper describes a new method for AVR parameter tuning for on line conditions using SQP(Sequential Quadratic Programming) meshed with frequency response characteristics of linearized on-line system model. As the proposed method uses the un - line system model the tuned parameter sets show more optimal behavior in the on-line operating conditions. furthermore, as this method considers the performance indices that are needed for stable operation as constraints, AVR parameter sets that are tuned by this method could guarantee the stable performance, too.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.217-220
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• 2001

Modified Materka-Kacprzak 대신호 MODFET(modulation-doped field-effect transistor) model을 사용하여 GaN(gallium nitride) MODFET 대신호 모델링을 수행하였다. Dambrine(3)이 제안한 방법에 따라 45㎒에서 40㎒의 주파수 범위에 걸쳐 S-parameter 및 DC특성을 측정하였으며, 측정결과를 토대로 cold FET 방법［4］에 의해 측정된 기생성분들을 de-embedding 함으로써 소신호 파라미터를 추출하였고, 추출된 소신호 파라미터는 함수를 사용하여 측정결과를 재현하는 맞춤함수 모델의 일종인 modified Materka 모델을 사용하여 모델링하였다. 수행된 대신호 모델링을 검증하기 위하여 모델링된 GaN MODFET의 DC 및 S-파라미터, 전력특성을 측정값과 각각 비교해 보았을 때 비교적 일치하고 있음을 보여서 GaN 대신호 모델링을 검증하였으며, modified Materka 모델이 GaN MODFET 대신호 모델링에 유용하게 사용될 수 있음을 보였다.

• 전자공학회논문지B
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• 제31B권3호
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• pp.39-46
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• 1994

In this paper, three types of parameter update law which can be used in model reference adaptive control are suggested based on speed-gradient algorithm which was introduced by Fradkov. It is shown that the parameter update law which was proposed by Narendra is a special from of these laws and that proposed parameter update laws can insure the global stability under some conditions such as attainability and convexity. We also comment that the transfer function of reference model shoud be positive real for the realization of parameter update law.

• 대한전기학회논문지
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• 제37권3호
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• pp.180-185
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• 1988

This paper considers the problem of the optimal input design for parameter estimtion in the ARMAX model in which the system and noise transfer function have the common denominator polynomial. Deriving the information matrix, in detail, for the assumed model structure and using the autocorrelation functin of the filtered input as design variables, it is shown that D-optimal input signal can be realized as an autoregressive moving average process. Computer simulations are carried out to show the standard-deviation reduction in the parameter estimtes using the optimal input signal.

• 한국공작기계학회논문집
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• 제17권3호
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• pp.8-13
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• 2008

The paper proposes a model-based measurement of unsteady flow rate by using distributed parameter pipeline model and the measured pressure values at two distant points along the pipeline. The distributed parameter model of hydraulic pipeline is applied with consideration of frequency dependent viscosity friction and unsteady velocity distribution at a cross section of a pipeline. By using the self-diagnostics functions of the measurement method, the validity is investigated by comparison with the measured and estimated pressure and flow rate wave forms at the halfway section on the pipeline. The results show good agreement between the estimated flow rate wave forms and theoretical those under unsteady laminar flow conditions. The method proposed here is useful in estimating unsteady flow rate through an arbitrary cross section in hydraulic pipeline and components without installing an instantaneous flowmeter.

• Journal of Electrical Engineering and Technology
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• 제1권3호
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• pp.302-307
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• 2006

The purpose of this paper is to develop an improved three-phase transformer model for ATP and parameter estimation methods that can efficiently utilize the limited available information such as factory test reports. In this paper, improved topologically-correct duality-based models are developed for three-phase autotransformers having shell-form cores. The problem in the implementation of detailed models is the lack of complete and reliable data. Therefore, parameter estimation methods are developed to determine the parameters of a given model in cases where available information is incomplete. The transformer nameplate data is required and relative physical dimensions of the core are estimated. The models include a separate representation of each segment of the core, including hysteresis of the core, ${\lambda}-i$ saturation characteristic and core loss.

• Interaction and multiscale mechanics
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• 제5권3호
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• pp.211-228
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• 2012

This paper reports the development of a generalized inverse analysis formulation for the parameter estimation of four-parameter Burger model. The analysis is carried out by formulating the problem as a mathematical programming formulation in terms of identification of the design vector, the objective function and the design constraints. Thereafter, the formulated constrained nonlinear multivariable problem is solved with the aid of fmincon: an in-built constrained optimization solver module available in MatLab. In order to gain experience, a synthetic case-study is considered wherein key issues such as the determination and setting up of variable bounds, global optimality of the solution and minimum number of data-points required for prediction of parameters is addressed. The results reveal that the developed technique is quite efficient in predicting the model parameters. The best result is obtained when the design variables are subjected to a lower bound without any upper bound. Global optimality of the solution is achieved using the developed technique. A minimum of 4-5 randomly selected data-points are required to achieve the optimal solution. The above technique has also been adopted for real-time settlement of four oil refineries with encouraging results.