• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.320-330
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• 2012

In this paper, we investigate the power integrity of grid structures for power and ground distribution on printed circuit board (PCB). We propose the 2D transmission line method (TLM)-based model for efficient frequency-dependent impedance characterization and PCB-package-integrated circuit (IC) co-simulation. The model includes an equivalent circuit model of fringing capacitance and probing ports. The accuracy of the proposed grid model is verified with test structure measurements and 3D electromagnetic (EM) simulations. If the grid structures replace the plane structures in PCBs, they should provide effective shielding of the electromagnetic interference in mobile systems. An analytical model to predict the shielding effectiveness (SE) of the grid structures is proposed and verified with EM simulations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.4
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• pp.390-402
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• 1997

The ignition noises from the vehicle are measured and the measurement data are statistically treated for modeling. The low-noise amplifier and band-pass filter are added between the receiver and the three axes antenna for low noise level measurement and the APD and PSD are measured in 800 MHz frequency range. The measured APD curves can be expressed in terms of sensitivity study of each model through 3(class A) or 6(Class B) parameters variation, and these optimal parameter can easily be calculated by using the Composite Approximation Algorithm. The selected APD parameter can be used for making the Data Base EM-environments and also applied to determine the output and sensitivity margin for the transmitter and receiver. 'Digital microwave transmission systems are equipped with equalizer against fading during multipath fading. In this paper, we proposed variable reference tap position equalizer that varies the reference tap according to fading type to archive better performance. We got the perf？mance improvement about 4~5 dB in MP condition and 2~3 dB in NMP condition from simulation results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.159-164
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• 2005

Recently, it has demanded high-speed digital circuits as information increase. Therefore, electromagnetic characteristics of compact microwave circuit occurred importantly. And, the effect of the imperfect ground plane on the signal integrity and influence of coupling between two parallel lines for high-speed digital transmission line on the printed circuit board is investigated by FDTD simulations in 3-D electromagnetic analysis method. The results of FDTD simulation are compared with the ADS simulation in commercial software, analyzed lumped element of modeling and electromagnetic wave's radiation of slot as frequency. As a consequence, when the slot in the ground plane is under microstrip line, it has much effect on propagation of wave.

• Korean Journal of Computational Design and Engineering
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• v.21 no.4
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• pp.409-416
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• 2016

This study aims to investigate dynamic interaction characteristics between Maglev train and 3 span continuous guideway. The integrated model including a 3D full vehicle model based on multibody dynamics, flexible guideway by a modal superposition method, and levitation electromagnets with the feedback controller is proposed. The proposed model was applied to the Incheon Airport Maglev Railway to analyze the dynamic response of the vehicle and guideway from the numerical simulation. Using field test data of air gap and guideway deflections, obtained from the Incheon Airport Maglev Railway, the analysis method is verified. From the results, it is confirmed that Maglev railway system are designed and constructed safely according to the design criteria.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.11
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• pp.1074-1080
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• 2013

The low phase noise and wideband frequency synthesizer has been designed by using YTO. Offset PLL structure is used for reducing a division ratio of feedback loop. The phase noise modeling is applied to optimize loop filter of PLL and YTO module. And DDS is used as reference signal of frequency synthesizer for fine resolution. The fabricated wideband frequency synthesizer has the output frequency of 3.2 GHz to 6.8 GHz, phase noise of -107 dBc/Hz at 10 kHz offset from the carrier and frequency resolution of 1 Hz. The measured phase noise is well agreed with the simulated one.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.1036-1042
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• 2005

The crosstalk between bent transmission lines and the effects of additional trace with the metal filled via holes on alleviating the crosstalk are investigated using the circuit concept approach for transmission line sections and impedance modeling for via hole sections. All sections are represented by ABCD matrices and then cascaded. Finally the calculated results by proposed method are confirmed that they agree with the measured results in less than 3 dB except a band of low frequency.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.5
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• pp.228-233
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• 2002

A computational method for analysis of the 3 dimensional electro-magnetic induction problems has been developed. The developed method is capable of modeling the induced current and analyzing its characteristics using only scalar Potential at each node. A benchmark model of asymmetrical conductor with a hole is analyzed to verify the application of the developed method. The calculated value of magnetic flux density are compared with the measured value, and the results indicate that the developed method is valid. Also, Comparing with 3-D finite element method (FEM) results, we conformed effectiveness of the developed method for the accuracy and computation times.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.38-44
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• 2021

To cater to the transition from single-color to multicolor/multi-material printing, this paper proposes a cartridge-replacing type multi-nozzle Fused Depositon Modeling(FDM) three-dimensional (3D) printer. In the test printing run, tool change failure/wobble/layer shift occurred. It was confirmed that improper support was the cause of this tool change failure. As a solution, spline and electromagnetic cartridges were designed. Wobble was caused by machine vibration and the motor stepping out. To minimize wobble, an additional Z-axis was installed, and the four-point bed leveling method was used instead of the three-point bed leveling method. The occurrence of layer shift was ascribed to the eccentricity of the Z-axis lead screw. Therefore, slit coupler was replaced with an Oldham type. In addition to the mechanical supplementation, the control environment was integrated to prevent accidents and signal errors due to wire connections. Before the final test printing run, a rectifier circuit was added to the motor to secure precise control stability. The final test printing run confirmed that the wobble/layer shift phenomenon was minimized, and the maximum error between layers was reduced to 0.05.

• Geophysics and Geophysical Exploration
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• v.7 no.2
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• pp.148-154
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• 2004

This article reviews the development of three-dimensional (3-D) magnetotelluric (MT) modeling. The 3-D modeling of electromagnetic fields is essential in understanding the physics of MT soundings, and in implementing an inversion method to reconstruct a 3-D resistivity image. Although various numerical schemes have been developed over the last two decades, practical methods have been quite limited. However, the recent rapid improvement in computer speed and memory, as well as the advance in iterative solution algorithms for a large system of equations, makes it possible to model the MT responses of complex 3-D structures, which have been very difficult to simulate before. The use of staggered grids in finite difference method has become popular, conserving a magnetic flux and an electric current and allowing for realistic discontinuous fields. The convergence of numerical solutions has been greatly accelerated by adopting Krylov subspace methods, proper preconditioning techniques, and static divergence corrections. The vector finite-element method using edge elements is also free from the discontinuity problem, and seems a natural choice for modeling complex structures including irregular topography because its flexibility allows one to capture full geometric complexity.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.4
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• pp.471-477
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• 2014

In this paper, a modeling and co-simulation methodology is proposed to predict the radiated electromagnetic interference (EMI) from on-chip switching I/O buffers. The output waveforms of I/O buffers are simulated including the on-chip I/O buffer circuit and the RC extracted on-chip interconnect netlist, package, and printed circuit board (PCB). In order to accurately estimate the EMI, a full-wave 3D simulation is performed including the measurement environment. The simulation results are compared with near-field electromagnetic scan results and far-field measurements from an anechoic chamber, and the sources of emission peaks were analyzed. For accurate far-field EMI simulation, PCB power trace models considering IC switching current paths and external power cable models must be considered for accurate EMI prediction. With the proposed EMI simulation model and flow, the electromagnetic compatibility can be tested even before the IC is fabricated.