• Journal of Environmental Science International
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• v.18 no.8
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• pp.911-918
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• 2009

Electromagnetic interference (EMI) is defined as the interaction phenomena of electromagnetic waves scattered from a large structure or complex terrain. In this study, the propagation of linear wave is modeled with ray theory, direct simulation Monte Carlo (DSMC), and some classical theories on flat plates. The wave physics of reflection, refraction, and diffraction are simulated for the investigation of front and back scattering of the one-dimensional plane wave from a tower with ray theory and DSMC, respectively. The effect of rotating disk idealized from the real wind-turbine blades is modeled with a simplified version of the classical electromagnetic theory as well as DSMC based on the ray theory.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.369-374
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• 2011

An induction motor operated with high voltage source generally generates high current in starting mode and has a long transient time after being started. This large and sustaining starting current causes the end windings of the stator to have excessive electromagnetic force. This force is the source of vibration and has a negative and serious influence on the insulation of end windings. Therefore, designing the end winding part with an appropriate support system is needed. To design the support ring enclosing the end windings, we analyze the distribution of electromagnetic force on the end windings by applying the Biot-Savart's law and the 3D finite element method (FEM), and comparing two simulation methods. Finally, we verify the safety of the support structure of the end winding part using stress analysis, which is analyzed with the electromagnetic forces from the 3D FEM simulation.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.6
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• pp.822-828
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• 2015

This paper describes computer simulation program of high-altitude electromagnetic pulse (HEMP). The HEMP is produced by the gamma rays form high-altitude nuclear explosion. The gamma rays generate a current of compton electron that leads to the production of electromagnetic fields. In case of high altitude nuclear burst, the electrical fields at the earth's surface are strong enough to be damaged for electrical and electronic device over a very much larger area. Therefore, national infrastructure will be serious damage such as power grid and communication network. In this paper introduce simulation program for calculation of HEMP and present to simulation study results of high altitude nuclear explosion experiment from U.S. and U.S.S.R.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1275-1276
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• 2015

Full wave electromagnetic simulation or fabricated models of an antenna are used to predict its radiation characteristics. In this work estimation of radiated power of an antenna based on its electrical model is presented. The computed radiated power using the electrical model have good agreement with the radiated power results obtained through the full wave electromagnetic simulation of the antenna model. The presented approach offers the advantage of saving of computation time of the full wave EM simulation.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.51-56
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• 2017

This study proposes a modeling process of equivalent terrains to reduce the computational load and time of a full-wave electromagnetic (EM) simulation. To verify the suitability of the proposed process, an original terrain model with a size of $3m{\times}3m$ is equivalently quantized based on the minimum range resolution of a radar, and the radar image of the quantized model is compared with that of the original model. The results confirm that the simulation time can be reduced from 407 hours to 162 hours without a significant distortion of the radar images, and an average estimation error of the quantized model (20.4 mm) is similar to that of the original model (20.3 mm).

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1832-1842
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• 2014

A novel probabilistic small signal stability analysis (PSSSA) method considering load correlation is proposed in this paper. The superiority Latin hypercube sampling (LHS) technique combined with Monte Carlo simulation (MCS) is utilized to investigate the probabilistic small signal stability of power system in presence of load correlation. LHS helps to reduce the sampling size, meanwhile guarantees the accuracy and robustness of the solutions. The correlation coefficient matrix is adopted to represent the correlations between loads. Simulation results of the two-area, four-machine system prove that the proposed method is an efficient and robust sampling method. Simulation results of the 16-machine, 68-bus test system indicate that load correlation has a significant impact on the probabilistic analysis result of the critical oscillation mode under a certain degree of load uncertainty.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.592-601
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• 2016

This paper presents the modeling of insulated-gate bipolar transistor (IGBT) in electromagnetic transients program (EMTP) simulation for the reliable calculation of switching and conduction losses. The conventional approach considering the physical property of switching devices requires many attribute parameters and large computation efforts. In contrast, the proposed method uses the curve fitting and interpolation techniques based on typical switching waveforms and a user-defined component with variable resistances to capture the dynamic characteristics of IGBTs. Therefore, the simulation time can be efficiently reduced without losing the accuracy while avoiding the extremely small time step, which is required in simulation by the conventional method. The EMTP based simulation includes turn-on and turn-off transients of IGBT, saturation state, forward voltage of free-wheeling diode, and reverse recovery characteristics, etc. The effectiveness of proposed modeling for the EMTP simulation is verified by the comparison with experimental results obtained from practical implementation in hardware.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.35-45
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• 2008

Electromagnetic Forming (EMF) technology such as magnetic pulse forming, which is one of the high velocity forming methods, has been used for the joining and forming process in various industry fields. This method could be derived a series of deformation of sheet metal by using a strong magnetic field. In this study, numerical approach by finite element simulation of the electromagnetic forming process was presented. A transient electromagnetic finite element code was used to obtain the numerical model of the time-varying currents that are discharged through the coil in order to obtain the transient magnetic forces. Also, the body forces generated in electromagnetic field were used as the loading condition to analyze deformation of thin sheet metal workpiece using explicit dynamic finite element code. In this study, after finite element analysis for thin sheet metal forming process with free surface configuration was performed, analytical approach for a dimpled shape by using EMF was carried out. Furthermore, the simulated results of the dimpled shape by EMF were compared with that by a conventional solid tool in view of the deformed shape. From the results of finite element analysis, it is confirmed that the EMF process could be applied to thin sheet metal forming.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.229-232
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• 2005

More than effectively judging the existence of voids behind concrete tunnel linings or under concrete pavements, this research aims to develop the analysis algorithm of radar capable of estimation of the shape of specific voids. To detect or estimate void shapes in non-reinforced concrete, the simulation analysis model of transmission and reflection wave of electromagnetic radar is used. This radar simulation model is carried out with various void shapes. As the results, a proposed method in this study has a possibility of detecting or estimating void shapes with good accuracy.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.169-172
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• 2002

In this paper, the design formulas for bandpass filters using parallel coupled stepped impedance resonators(SIR) are derived. General content about basic feature of stepped impedance resonators(SIR) is represented. The filters and duplexer using stepped impedance resonators(SIR) have been designed and realized with the presented design method at IMT-2000 frequency band Simulations have used serenade circuit simulation and HFSS EM-simulation. We were showed excellent agreements between SIR design theory and simulation results on the multi-layer filter/duplexer.