• Journal of Power Electronics
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• v.17 no.2
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• pp.501-513
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• 2017

The fundamental small-signal modeling of lithium-ion (Li-ion) batteries and a parameter evaluation approach are investigated in this study to describe the dynamic behaviors of small signals accurately. The main contributions of the study are as follows. 1) The operational principle of the small signals of Li-ion batteries is revealed to prove that the sinusoidal voltage response of a Li-ion battery is a result of a sinusoidal current stimulation of an AC small signals. 2) Three small-signal measurement conditions, namely stability, causality, and linearity, are proved mathematically proven to ensure the validity of the frequency response of the experimental data. 3) Based on the internal structure and electrochemical operational mechanism of the battery, an AC small-signal model is established to depict its dynamic behaviors. 4) A classical least-squares curve fitting for experimental data, referred as Levy's method, are introduced and developed to identify small-signal model parameters. Experimental and simulation results show that the measured frequency response data fit well within reading accuracy of the simulated results; moreover, the small-signal parameters identified by Levy's method are remarkably close to the measured parameters. Although the fundamental and parameter evaluation approaches are discussed for Li-ion batteries, they are expected to be applicable for other batteries.

• 전자공학회논문지 IE
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• v.44 no.2
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• pp.1-7
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• 2007

The increasing high frequency capabilities of CMOS have resulted in increased RF and analog design in CMOS. Design of RF and analog circuits depends critically on device S-parameter characteristics, magnitude of real and imaginary components and their behavior as a function of frequency. Utilization of scaled high performance CMOS technologies poses challenges as concerns for reliability degradation mechanisms increase. It is important to understand and quantify the effects of the reliability degradation mechanisms on the S-parameters and in turn on small signal model parameters. Various physical effects influencing small-signal parameters, especially the transconductance and capacitances and their degradation dependence, are discussed in detail. The measured S-parameters of H-gate and T-gate devices in a frequency range from 0.5GHz to 40GHz. All intrinsic and extrinsic parameters are extracted from S-parameters measurements at a single bias point in saturation. In this paper we discuss the analysis of the small signal equivalent circuits of RF SOI MOSFET's verificated for the purpose of exacting the change of parameter of small signal equivalent model followed by device flame.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1910-1915
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• 2007

An accurate and simple method to extract equivalent circuit parameters of fully-depleted silicon-on-insulator MOSFETs small-signal modeling operating at RF frequencies including the non-quasi static effects is presented in this article. The advantage of this method is that a unique and physically meaningful set of intrinsic equivalent circuit parameters is extracted by de-embedding procedure of extrinsic elements such as parasitic capacitances and resistances of MOSFETs from measured S-parameters using simple Z- and Y- matrices calculations. The calculated small-signal parameters using the presented extraction method give modeled Y-parameters which are in good agreement with the measured Y-parameters from 0.5 to 20GHz.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.4
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• pp.377-387
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• 2012

An intrinsic small signal equivalent circuit model of Cylindrical/Surrounded gate MOSFET is proposed. Admittance parameters of the device are extracted from circuit analysis and intrinsic circuit elements are presented in terms of real and imaginary parts of the admittance parameters. S parameters are then evaluated and justified with the simulated data extracted from 3D device simulation.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.357-360
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• 2000

This paper describes a parameter extraction method for HBT(Heterojunction Bipolar Transistor) equivalent circuit model without measurements of special test structures or numerical optimizations. Instead, all equivalent circuit parameters are calculated analytically from small-signal S-parameters measured under different bias conditions. These values being extracted from the cutoff mode can be used to extract intrinsic parameters at the active mode. This method yields a deviation of about 1.3 % between the measured and modeled S-parameters.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.957-960
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• 2000

A novel extraction method of high frequency small-signal model parameters for MOSFETS is proposed. From S-parameter measurement, this technique accurately extracts the model parameters including the charge conservation capacitance parameters. To consider charge conservation, nonreciprocal capacitance is considered. The modeled parameters fit the measurements very well without any optimization.

• Journal of Korean Society of Transportation
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• v.14 no.3
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• pp.127-141
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• 1996

This paper presents a unique approach to urban traffic network signal control. This paper begins with an introduction to traffic control in general, and then goes on to describe the approach of fuzzy control, where the signal timing parameters at a given intersection are adjusted as functions of the local traffic network condition and adjacent intersection. The signal timing parameters evolve dynamically using only local information to improve traffic signal flow. The signal timing at an intersection is defined by three parameters : cycle time, phase split, off set. Fuzzy decision rules are used to adjust three parameters based only on local information. The amount of change in the timing parameters during each cycle is limited to a small fraction of the current parameters to ensure smooth transition. In this paper the effectiveness of this method is showed through simulation of the traffic signal flow in a network of controlled intersection.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.4
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• pp.1-6
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• 2012

This paper presents the extraction and analysis of small-signal parameters of tunneling field-effect transistors (TFETs) by using TCAD device simulation. The channel lengths ($L_G$) of the simulated devices varies from 50 nm to 100 nm. The parameter extraction for TFETs have been performed by quasi-static small-signal model of conventional MOSFETs. The small-signal parameters of TFETs with different channel lengths were extracted according to gate bias voltage. The $L_G$-dependency of the effective gate resistance, transconductance, source-drain conductance, and gate capacitance are different with those of conventional MOSFET. The $f_T$ of TFETs is inverely proportional not to $L_G{^2}$ but to $L_G$.

• Smart Structures and Systems
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• v.19 no.5
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• pp.499-512
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• 2017

Traditional structural dynamic analysis and Structural Health Monitoring (SHM) of large scale concrete civil structures rely on manufactured embedding transducers to obtain structural dynamic properties. However, the embedding of manufactured transducers is very expensive and low efficiency for signal acquisition. In dynamic structural analysis and SHM areas, piezoelectric transducers are more and more popular due to the advantages like quick response, low cost and adaptability to different sizes. In this paper, the applicable feasibility assessment of the designed "artificial" piezoelectric transducers called Concrete Piezoelectric Smart Module (CPSM) in dynamic structural analysis is performed via three major experiments. Experimental Modal Analysis (EMA) based on Ibrahim Time Domain (ITD) Method is applied to experimentally extract modal parameters. Numerical modal analysis by finite element method (FEM) modeling is also performed for comparison. First ten order modal parameters are identified by EMA using CPSMs, PCBs and FEM modeling. Comparisons are made between CPSMs and PCBs, between FEM and CPSMs extracted modal parameters. Results show that Power Spectral Density by CPSMs and PCBs are similar, CPSMs acquired signal amplitudes can be used to predict concrete compressive strength. Modal parameter (natural frequencies) identified from CPSMs acquired signal and PCBs acquired signal are different in a very small range (~3%), and extracted natural frequencies from CPSMs acquired signal and FEM results are in an allowable small range (~5%) as well. Therefore, CPSMs are applicable for signal acquisition of dynamic responses and can be used in dynamic modal analysis, structural health monitoring and related areas.

• International Journal of Control, Automation, and Systems
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• v.3 no.spc2
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• pp.355-362
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• 2005

Deregulations and market practices in power industry have brought great challenges to the system planning area. In particular, they introduce a variety of uncertainties to system planning. New techniques are required to cope with such uncertainties. As a promising approach, probabilistic methods are attracting more and more attentions by system planners. In small signal stability analysis, generation control parameters play an important role in determining the stability margin. The objective of this paper is to investigate power system state matrix sensitivity characteristics with respect to system parameter uncertainties with analytical and numerical approaches and to identify those parameters have great impact on system eigenvalues, therefore, the system stability properties. Those identified parameter variations need to be investigated with priority. The results can be used to help Regional Transmission Organizations (RTOs) and Independent System Operators (ISOs) perform planning studies under the open access environment.