• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1355-1361
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• 2016

The inter-turn fault (ITF) causes the negative sequence components in the d -q voltage equation due to an increase in the unbalance of three-phase input currents. For this reason, d -q voltage equation become complicate as the voltage equation is classified into positive and negative components. In this study, we propose a simplified d -q equivalent circuit of an interior permanent magnet synchronous motor under ITF state. First, we proposed modeling method for d -q current based on the finite element method simulation results. Then, we developed the simplified d -q equivalent circuit by applying the proposed d -q current modeling.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.600-602
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• 2006

Some abnormal signals diagnostics and analysis through an important equivalent circuits modeling for passive elements under severe accident conditions have been performed. Unlike the design basis accidents, there are inherently some uncertainties in the instrumentation capabilities under the accident conditions. So, the circuit simulation analysis and diagnosis methods are used to assess instruments in detail when they give apparently abnormal readings as an accident alternative method. The simulations can be useful to investigate what the signal and circuit characteristics would be when similar to a variety of symptoms that can result from the environmental conditions such as high temperature, humidity, and pressure condition. In this paper, a new simulator through an analysis of the important equivalent circuits modeling under temperature accident conditions has been designed, the designed simulator is composed of the LabVIEW code as a main tool and the out-put file of the Multi-SIM code as an engine tool is exported to in-put file of the LabVIEW code. The procedure for the simulator design was divided into two design steps, of which the first step was the diagnosis method, the second step was the circuit simulator for the signal processing tool. It has three main functions which are a signal processing tool, an accident management tool, and an additional guide from the initial screen. This simulator should be possible that it could be applied a output signal analysis to some transient signal by variation of the resistance passive elements in the R-L-C equivalent circuit modeling under various degraded conditions in NPPs.

• Composites Research
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• v.16 no.5
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• pp.7-14
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• 2003

Modeling of thick composite structures for finite element analysis is relatively complicated. 2-D plane elements may cause inaccurate result since the plane stress condition cannot be applicable in these structures. Therefore a 3-D modeling should be used. However, the difficulty to model all the layers with different material properties and ply orientation arise in this case. In this paper, an equivalent modeling is proposed and numerically tested for analysis of thick composite structures. By grouping layers with same material and ply orientation, number of elements through the thickness is remarkably reduced and still the result is close enough to the one from a detail finite element model. MSC/NASTRAN and PATRAN are used for the analysis. The proposed modeling technique has been applied for analysis of composite rotor hub system designed by Korea Aerospace Research Institute(KARI). Using the proposed equivalent modeling technique, we could conduct stress analysis for the hub system and check the safety factor of each part.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.1
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• pp.1-11
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• 2015

In order to perform a soil-isolation-structure interaction analysis of seismically isolated nuclear power plant (NPP) structures, the nonlinear behavior of a seismic isolation system may be converted to an equivalent linear model used in frequency domain analysis. Seismic responses for seismically isolated NPP containment structures subjected to a simple artificial acceleration history and different site class earthquakes are evaluated for the equivalent-linear and nonlinear models that have been applied to lead-rubber bearing (LRB) modeling. It can be observed that the maximum displacements of the equivalent linear model are larger than that of the nonlinear model. From the floor response spectrum analysis for the top of NPP containment structures, it can be observed that the spectral acceleration of an equivalent linear model at about 0.5 Hz frequency is about 2~3 times larger than that of a nonlinear model.

• Journal of Power Electronics
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• v.17 no.2
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• pp.442-452
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• 2017

This paper deals with the input-output modeling of a vector controlled PMSM drive system and design of a simple multiple model adaptive control (MMAC) scheme with desired transient responses. We present a discrete-time modeling technique using closed-loop identification that can experimentally identify the equivalent models in the d-q coordinates. A bank of linear models for the equivalent plant of the current loop is first obtained by identifying them at several operating points of the current to account for nonlinearity. Based on these models, we suggest a simple q-axis MMAC combined with a fixed d-axis controller. After the current controller is designed, another equivalent model including the current controller in the speed control loop shall be similarly obtained, and then a fixed speed controller is synthesized. The proposed approach is demonstrated by experiments. The experimental set up consists of a surface mounted PMSM (5 KW, 220V, 8 poles) equipped with a flywheel load of 220kg and a digital controller using DSP (TMS320F28335).

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.512-515
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• 1991

The advantages of poly-phase converter are to be able to reduce the ripple current and to lessen the weight of power inductors. This paper is derived the equivalent circuit, dc of and ac modeling circuit of a 3-phase multiple buck converter by using state space representation and averaging techniche. Futhermore, it is represented the equivalent circuits according to the duty cycle.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.49-52
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• 1998

In this paper, to implement the electrical equivalent modeling of powder electroluminescent device, capacitate equation of device was chosen. The conventional structure device which have dielectric and phosphor layer between electrodes, and the single emission structure device which means that dielectric and phosphor were mixed between electrodes, were investigated. As a result, it was possible to make the equation that is transferred capacitance to phosphor layer, and using measured brightness efficiency and conductivity of devices was calculated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.743-749
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• 2003

By biasing the gate of cold-HEMT with a voltage slightly lower than the pinch-off point, a new small-signal modeling method that is free from gate degradation problem and requires no additional DC measurement is proposed in this paper. The method has shown excellent agreement between modeled and measured S-parameters up to 62 GHz at 49 different normal operating bias points.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1138-1143
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• 2015

Effects of fabrication process variations on impedance of microelectrodes integrated on a neural probe were examined through equivalent circuit modeling and SPICE simulation. Process variation and the corresponding range were estimated based on experimental data. The modeling results illustrate that the process variation induced by metal etching process was the dominant factor in impedance variation. We also demonstrate that the effect of process variation is frequency dependent. Another process variation that was examined in this work was the thickness variation induced by deposition process. The modeling results indicate that the effect of thickness variation on impedance is negligible. This work provides a means to predict the variations in impedance values of microelectrodes on neural probe due to different process variations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.88-93
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• 2003

This paper presents an efficient dynamic modeling method for open cracked rotor-bearing systems. An equivalent bending spring model is introduced to represent the structural weakening effect in the presence of cracks. The proposed modeling method is validated through a series of simulations and experiments. First, the proposed method is rigorously compared with a commercial finite element code. Then, an experiment is performed to validate the proposed modeling method. Finally, a numerical example is introduced to demonstrate the possible application of the proposed method in the crack diagnosis fur rotor systems.