• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.2
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• pp.105-116
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• 1996

The design and analysis of the transversely fed EMC(electromagnetically coupled) microstrip dipole have been accomplished by using the integral equation and MOM(method of moment)in frequency domain in order to find the current distribution of the dipole. In this study, we proposed the possibilities for design and analysis of EMC micro-strip dipole array antenna by means of calculating the current distribution of each dipole directly using the FDTD(finite difference time domain) method. In this case, we applied the formulation which is the finite difference expression of the Maxwell's integral equation. From the current distribution of each dipole, we calculated the far field electric component and showed that the calculation process and running time was reduced with respect to the method which calculates the radiation field with surface electric and magnetic current density.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.776-787
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• 1998

This paper analyzes the local specific absorption rates (SAR's) averaged over 1 g and 10 g in a human head model in contact with a mobile phone operating at 835 MHz. The used numerical method is a total field finite-difference time-domain (FDTD) technique. The phone was simulated with a conducting box, a plastic case, and a whip antennal composed of a monopole and a helix. The discrete human model of the spatial resolution 3 mm is based on Magnetic Resonance Imaging (MRI), computerized tomography (CT) and anatomical images. The near field and far field and far field patterns were analyzed for extended and retracted phone. The two methods to take the volumes of the weights, 1 g or 10 g in tissue are proposed and compared to offer a reproductive technique for SAR estimations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.839-848
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• 2000

This paper presents the results of an electromagnetic field analysis for a reverberation chamber that is an alternative method of a shielded anechoic chamber, which is widely used for the analysis and measurement of electromagnetic interference and immunity test. Inside the defined test volume of the rectangular and triangular type, the Schroeder Quadratic Residue Diffuser was employed. FDTD(Finite-Difference Time-Domain) simulation method was applied to produce the field characteristics inside those reverberation chambers. According to the results, field uniformities on the aforementioned two types of reverberation chambers were correlated within $\pm$3dB, and $\pm$4.4dB tolerances, and rectangular type reverberation chamber shows an independent polarization result.

• Korean Journal of Optics and Photonics
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• v.24 no.2
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• pp.53-57
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• 2013

A polarization selective blazed grating employing metal-slit arrays was proposed. Nano-scale metal-slits were applied to the micro-scale blazed grating to give the functionality of polarization selection. Case study was carried out for the proposed structure utilizing numerical FDTD (Finite Difference Time Domain method) simulation. Diffraction efficiency of 77.61% and polarization extinction ratio of 8.99 was achieved with arbitrary parameters and diffraction efficiency of 64.22% and polarization extinction ratio of 81.09 was achieved with other parameters to enhance extinction ratio.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.48-65
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• 1995

This paper deals with the analysis of the unintentional radiation from the TDX-1B subscriber Board. According to the demand of digital systems and developement of high speed switching devices, electro- magnetic noise intensity and it's bandwidth occupancy in spectrum are increasing and so there is a serious possibility causing the various EMI phenomena. More accurate radiation model was established by using the Finite Difference Time Domain (FDTD) analysis, and the EMI probabilistic analysis of the digital switching system was performed. For validating the proposed model and its calculated results, on-promises test was performed and compared with the calculated results. These results may be applicable to be used for EMI model in large digital system, and prediction of EMI effect from a large digital system, and the EMI control design when designing digital system to meet inter- national EMI regulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.528-537
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• 2002

In this paper, the extended FDTD is used for the analysis of microwave circuits including active elements. Lumped elements such as R, L, C which are inserted into a microstrip line are analyzed with the FDTD lumped element modeling. Parasitic capacitance and inductance could be obtained using network modeling and so it is sure that FDTD lumped element modeling makes it possible to get more accurate data which include parasite components. Moreover, a balanced mixer using two diodes that are modeled by an extended FDTD is designed and the more exact characteristic of the mixer is acquired than in current circuit simulator.

• Journal of Broadcast Engineering
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• v.19 no.6
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• pp.934-941
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• 2014

In this paper, we present a low profile 2-layered meander built-in monopole antenna for portable RFID reader using FDTD(Finite Difference Time Domain) method. The input impedance, return loss, and VSWR in the frequency domain are calculated by Fourier transforming the time domain results. The double meander 2-layer structure is used to enhance the impedance matching and increase the antenna gain. The measured bandwidth of the antenna is 0.895 GHz ~ 0.930 GHz for a S11 of less than -10dB. The measured peak gain of proposed low profile RFID built-in antenna is 2.3 dBi. And the proposed built-in antenna for portable RFID reader can offers relatively wide-bandwidth and high-gain characteristics, in respectively. Experimental data for the return loss and the gain of the antenna are also presented, and they are relatively in good agreement with the FDTD results. This antenna can be also applied to mobile communication field, energy fields, RFID, and home-network operations, broadcasting, and other low profile mobile systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1165-1172
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• 2008

In this paper, the scattering parameters of the metamaterial slab are obtained using the 2D FDTD(Finite-Difference Time-Domain) method. FDTD method is one of strongest electromagnetic numerical method which is widely used to analyze the metamaterial structure because of its simplicity. But it is very difficult to obtain frequency response of metamaterial itself because frequency dispersive model such as Lorentz, Drude model are used in FDTD. We used the well-known m-n-m cycle sine pulse to obtain the frequency response of the metamaterials. Comparisons between the wideband Gaussian input pulse and band-limited m-n-m cycle sine pulse are performed in this paper also. From the results, we concluded that the scattering parameters in frequency domain can be obtained using specific input pulse in FDTD even if the response has valid only for limited bandwidth.

• ETRI Journal
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• v.35 no.5
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• pp.915-918
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• 2013

This work presents an accurate finite-difference time-domain (FDTD) dispersive modeling of concrete materials with different water/cement ratios in 50 MHz to 1 GHz. A quadratic complex rational function (QCRF) is employed for dispersive modeling of the relative permittivity of concrete materials. To improve the curve fitting of the QCRF model, the Newton iterative method is applied to determine a weighting factor. Numerical examples validate the accuracy of the proposed dispersive FDTD modeling.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.163-164
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• 2006

In this paper, an analytical laser ablation model with Maxwell equation will be addressed by considering relationship between laser ablation and material. The Maxwell equation consists of four equations: two Gauss laws for electric and magnetic fields, Faraday's law, and Ampere's law. This analytical model will be calculated by employing Finite Difference Time Domain (FDTD). This method also makes it possible to simulate the laser beam propagation in a wide range of materials, such as metals, semiconductors, and dielectrics. Therefore, in this study, a numerical model for short pulse laser interaction with materials is developed, focusing on the accurate description of laser beam propagation and ablation process into the material with each pulse.