• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.9
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• pp.680-684
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• 1991

The scattering problem of a transverse electric (TE) plane wave by strip grating with a dielectric slab over a ground plane is analyzed by the method of moments. By use of equivalence principle, surface magnetic current density on the shorted slot is expanded in a series of Chebyshev polynomial a satisfying the appropriate edge condition. Numerical results for reflection coefficient are obtained and compared with other available results. Our numerical results obtained from the present method are in good agreement with other result available in the literature.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.209-214
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• 2017

A plane-wave incident upon asymmetric multi-layered dielectric grating as well as symmetric grating structure generates space harmonics. Selected space harmonics among those harmonics can undergo strong resonance scattering variations known as GMR(guided-mode resonance). In this paper, to clarify these effects, the field propagation and dispersion curve inside the grating region are analyzed by using a rigorous equivalent transmission-line theory(RETT) based on eigenvalue problem. The results show that, at the peak of a scattering resonance, the reflected mode is almost identical to a leaky wave that can be supported by the grating structure. Thus, it confirms to be occurred GMR effect associated with the free-resonant character of leaky waves at asymmetric multi-layered dielectric gratings. Quantitative simulation results illustrating the behavior of typical gratings are given, and the special case of normal incidence is discussed for TE and TM modes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.12
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• pp.1935-1944
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• 1993

We calculate the optimum refractive index and thickness for a single layer antireflection coating as a function of active layer thickness of a laser diode using three different simplified numerical methods. The difference of the results using three methods comes from that of the effective refractive index of a laser used in three methods. We compare three simplified methods to an exact method to check the validity of the simplified methods. We conclude that the simplified method, choosing the effective index of a laser diode as a function of incidence angle of each plane wave composing of a guided mode agree well to an exact method for both TE and TM modes and the cases of strongly and weakly guiding.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.5
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• pp.1-6
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• 1997

An analysis method for the electromagnetic scattering of a tE polarized plane wave from a periodic strip grating over a grounded dielectric slab is consisered from the viewpoint of reflectio ngraing problem. The strip gratings showing bragg and off-bragg balzing phenomena at the frequency of 10GHz are designed, respectively. The strip grating structure is implemented using aluminum plate (hround conductor), paraffin(dielectric material ; .xi.$_{\gamma}$=2.24) and copper (strip conductor ; 0.08mm thickness). The experimental results (reflection power) for bragg as well as off-bragg blazing phenomenon have been compared with the theoretical results and fairly good agreements between theory and experiment have been observed.ed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1094-1102
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• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside conducting screen of finite thickness is considered for the case that the TE(to the slit axis) polarized plane wave is incident on the slit in conducting screen. Using the method of moments the variations of the transmitted power through the slits are obtained and compared with those computed from an equivalent circuit constructed using an equivalent slit admittance. It is found that the effective slit width of a narrow slit, at resonance, becomes $1/{\pi}$ wavelengths independently of the actual slit width. The transmission resonance phenomena in the proposed geometry are explained in connection with the variations of an equivalent admittance of the slit in the cavity.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.283-288
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• 2011

In this study, a wide-band photonic crystal Y-splitter for TE modes is proposed. A triangular lattice of air holes etched in a GaAs slab is used as the platform. In order to numerically analyze the structures, plane wave expansion (PWE) and finite difference time domain (FDTD) methods are used. In comparison with the structures reported in the literature, the proposed topology has a less complexity while it provides more than 100nm bandwidth. The simplicity of the design, its high transmission ratio and its wide bandwidth makes it a suitable choice for the implementation of photonic crystal integrated circuits.

• Journal of the Korean Magnetics Society
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• v.10 no.1
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• pp.22-29
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• 2000

The effective linewidth was measured using the conventional cavity perturbation method at 9.43 GHz in room temperature for Ca-Zr substituted yttrium iron garnet plate. The experimental set-up consists of the network analyzer, the electromagnet and the cylimdrical TE001 cavity. Measurement was performed in the static magnetic field perpendicular to the sample plane. The real and imaginary parts of diagonal component of the microwave susceptibility tensor are obtained from the resonance frequency and the quality factor Q of the cavity. Variations of the effective linewidth was qualitatively explained with the spin wave scattering theory.

• Journal of the Korean Magnetics Society
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• v.26 no.2
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• pp.39-44
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• 2016

Determination of the structural, electronic, and magnetic properties of the magnetically doped bismuth-telluride alloys are drawing lots of interest in the fields of the thermoelectric application as well as the research on magnetic interaction and topological insulator. In this study, we performed the first-principles electronic structure calculations within the density functional theory for the Gd doped bismuth-tellurides in order to study its magnetic properties and magnetic phase stability. All-electron FLAPW (full-potential linearized augmented plane-wave) method is employed and the exchange correlation potentials of electrons are treated within the generalized gradient approximation. In order to describe the localized f-electrons of Gd properly, the Hubbard +U term and the spin-orbit coupling of the valence electrons are included in the second variational way. The results show that while the Gd bulk prefers a ferromagnetic phase, the total energy differences between the ferromagnetic and the antiferromagnetic phases of the Gd doped bismuth-telluride alloys are about ~1meV/Gd, indicating that the stable magnetic phase may be changed sensitively depending on the structural change such as defects or strains.

• Journal of the Korean Magnetics Society
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• v.23 no.1
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• pp.1-6
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• 2013

Spin-orbit coupling (SOC) effect is known to be the physical origin for various exotic magnetic phenomena in the low-dimensional systems. Recently, SOC also draws lots of attention in the study on magnetically doped thermoelectric alloys to determine their properties as the thermoelectric application as well as the topological insulator via the exact electronic structures determination near the Fermi level. In this research, aiming to investigate the spin-orbit coupling effect on the structural properties such as the lattice constants and the bulk modulus of the most widely investigated thermoelectric host material, $Bi_2Te_3$, we carried out the first-principles electronic structure calculation using the all-electron FLAPW (full-potential linearized augmented plane-wave) method. Employing both the local density approximation (LDA) and the generalized gradient approximation (GGA), the structural optimization is achieved by varying the in-plane lattice constant fixing the perpendicular lattice constant and vice versa, to find that the SOC effect increases the equilibrium lattices slightly in both directions while it markedly reduces the bulk modulus value implying the strong orientational dependence, which are attributed to the material's intrinsic structural anisotropy.

• Journal of Biosystems Engineering
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• v.36 no.1
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• pp.23-32
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• 2011

In this work, the finite element method was used to investigate the shifts of resonance frequencies and quality factor of whispering-gallery-mode (WGM) for an opto-fluidic ring resonator (OFRR) biosensor. To describe the near-field radiation transfer, the time-domain Maxwell's equations were employed and solved by using the in-plane TE wave application mode of the COMSOL Multiphysics with RF module. The OFRR biosensor model under current study includes a glass capillary with a diameter of 100 mm and wall thickness of 3.0 mm. The resonance energy spectrum curves in the wavelength range from 1545 nm to 1560 nm were examined under different biosensing conditions. We mainly studied the sensitivity of resonance shifts affected by changes in the effective thickness of the sensor resonator ring with a 3.0 mm thick wall, as well as changes in the refractive index (RI) of the medium inside ring resonators with both 2.5 mm and 3.0 mm thick walls. In the bulk RI detection, a sensitivity of 23.1 nm/refractive index units (RIU) is achieved for a 2.5 mm thick ring. In small molecule detection, a sensitivity of 26.4 pm/nm is achieved with a maximum Q-factor of $6.3{\times}10^3$. These results compare favorably with those obtained by other researchers.