• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• 제11권4호
• /
• pp.565-574
• /
• 2000

A new ground penetrating radar imaging method for the estimation of buried artificial structures location and their approximate shapes in dispersive lossy ground is investigated. Fundamental idea is based on estimating delayed time and amplitude retrieval coefficients from scattered signals by buried scatterers. Using absolute value integration of each scanning site not only improve the accuracy of measured scattered signal, but also offers convenient ways to extract the image of buried structures. Multi-term Debye model was employed to describe a dispersive and lossy ground medium. We used the finite difference time domain method to discretize the wave equation in continuous form into the machine suitable form. This imaging method uses a new wave path tracing technique in time domain, which is helpful to identify the exact position of buried structures against the ground surface fluctuations.

• 연구논문집
• /
• 통권33호
• /
• pp.17-25
• /
• 2003

In this work, thermal design of a PCR chip for LOC is systematically conducted. From the numerical simulation of a PCR chip based on the finite volume method, how to control the average temperature of a PCR chip and the temperature difference between the denaturation zone and the annealing zone is presented. The average temperature is shown to be controlled by adjusting heat input and a cooler as well as a heater is shown to be necessary to obtain three individual temperature zones for polymerase chain reaction. To reduce the time required, a heat sink for the cooler is not included in the calculation domain for the PCR chip and heat sink design is conducted separately by using a compact modeling method, the porous medium approach.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• 제6권3호
• /
• pp.3-14
• /
• 1995

The broadband input impedance, the input power and the radiation pattern of the monopole antenna attached to the handy phone operated at 800MHz are calculated by using the Finite Difference Time Domain(FDTD) Method. For the FDTD analysis of frequency characteristics of monopole antenna, the handy phone is modeled with the geometry that the monopole antenna is connected to a conducting box, and the modified FDTD algorithm[11] used the thin wire appproximation method and the Maxwell's integral equation from the original Yee algorithm is applied for the analysis of the wire structure. Also, by means of finding the current distribution directly from circumferencial magnetic filelds around the monopole antenna and the conducting box, the radiation pattern is calculated to observe the influence of the conducting box, and is compared with the results of the known mothod for the FDTD calculation of radiation pattern, For the experiments, the handy phone of which full length including antenna is .lambda. $\lambda$/2 is manufactured and we confirm that all computation results are agree well with the mea- sured values.

• Bulletin of the Korean Chemical Society
• /
• 제28권12호
• /
• pp.2200-2202
• /
• 2007

The local field distribution around gold nanosphere-gold plane junction has been studied using the finitedifference time-domain (FDTD) electrodynamics calculation procedure. We find that both the in-plane and out-of-plane polarized excitation produce enhanced field strong enough to explain the observed SERS activities of the junctions. Comparison with a simple dipole-image dipole model shows that the enhanced field primarily originates from the multipole-image multipole interaction, which indicates that the detailed fine-structures of the nanoparticles also play a significant role in the SERS activities as well.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• 제11권2호
• /
• pp.95-106
• /
• 1999

A numerical model is represented to calculate the wave fields such as the reflected waves, the transmitted waves and the depth-averaged velocities over submerged breakwaters for the normally incident wave trains of nonlinear mono-chromatic wave and solitary wave. The finite amplitude shallow water equations with the effects of bottom friction are solved numerically in time domain using an explicit dissipative Lax-Wendroff finite difference method. The numerical model is verified by comparisons with the other numerical results and the measured data. It is found that the submerged breakwater may be more useful for protecting the energies of monochromatic waves rather than solitary waves. Finally, the armor stability on submerged breakwater is indirectly analyzed using the hydrodynamic characteristics of flow fields.

• Journal of Broadcast Engineering
• /
• 제18권6호
• /
• pp.911-918
• /
• 2013

The proposed print antenna using Finite Difference Time Domain(FDTD) method is analyzed in this paper. A low radiation resistance and an ultra-wide band of this antenna are also presented. The propagation process of the reflected wave and the electric field distribution in the time domain are calculated in respectively. The antenna parameters are optimized for the maximum band width, return loss, input impedance, and radiation pattern in the frequency domain using Fourier transforming. The experimental bandwidth of the antenna is 1.85GHz~6.35GHz for the VSWR less than or equal to 2.0. The measured results are relatively in good agreement with the FDTD results. The proposed antenna can be applied to various applications such as UWB, broadcasting-network system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• 제19권4호
• /
• pp.427-435
• /
• 2008

In this paper, a stable marching-on in time(MOT) method with a time domain combined field integral equation(CFIE) is presented to obtain the transient scattering response from arbitrarily shaped three-dimensional conducting bodies. This formulation is based on a linear combination of the time domain electric field integral equation(EFIE) with the magnetic field integral equation(MFIE). The time derivatives in the EFIE and MFIE are approximated using a central finite difference scheme and other terms are averaged over time. This time domain CFIE approach produces results that are accurate and stable when solving for transient scattering responses from conducting objects. Numerical results with the proposed MOT scheme are presented and compared with those obtained from the conventional method and the inverse discrete Fourier transform(IDFT) of the frequency domain CFIE solution.

• ETRI Journal
• /
• 제31권4호
• /
• pp.387-392
• /
• 2009

This paper introduces a novel parallel shift operator finite-difference time-domain (SO-FDTD) method for plasma in the dispersive media. We calculate the interaction between the electromagnetic wave of various frequencies and non-magnetized plasma by using the parallel SO-FDTD method. Then, we compare the results，which are calculated with serial and parallel SO-FDTD executions to obtain the speedup ratio and validate the parallel execution. We conclude that the parallel SO method has almost the same precision as the serial SO method, while the parallel approach expands the scope of memory and reduces the CPU time.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• 제40권5호
• /
• pp.181-186
• /
• 2003

This paper presents a numerical dispersion relation for the two-dimensional finite-difference time-domain method based on the alternating-direction implicit time-marching scheme(2-D ADI-FDTD), which method has the potential to considerably reduce tile number of time iterations especially in case where the fine spatial lattice relative to the wavelength is used to resolve fine geometrical features. The proposed analytical relation for 2-D ADI-FDTD is compared with those relations in the Previous works. Through numerical tests, the dispersion equation of this work was shown as correct one for 2-D ADI-FDTD.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• 제23권1호
• /
• pp.108-114
• /
• 2012

We propose a dispersive finite-difference time domain(FDTD) algorithm suitable for the electromagnetic analysis of the human body. In this work, the dispersion relation of the human body is modeled by a quadratic complex rational function(QCRF), which leads to an accurate and efficient FDTD algorithm. Coefficients(involved in QCRF) for various human tissues are extracted by applying a weighted least square method(WLSM), referred to as the complex-curve fitting technique. We also presents the FDTD formulation for the QCRF-based dispersive model in detail. The QCRFbased dispersive model is significantly accurate and its FDTD implementation is more efficient than the counterpart of the Cole-Cole model. Numerical examples are used to show the validity of the proposed FDTD algorithm.