• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.7
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• pp.1-7
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• 1989

For H-polarized incident plane wave, an exact integral expression for the scattered field by an inversely tapered resistive half plane is obtained by using Kontorovich-Lebedev transform. Uniform asymptotic results available for all angles are obtained, and non-uniform asymptotic results which provide the ray-optical interpretation of the calculated scattered field are also obtained. The edge diffraction patterns for several values of inverse proportionality of resistivity are shown. We find out that the results are in agreement with physical reasoning.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.877-880
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• 1999

A rigorous formulation is suggested〔l,2,3〕 in solving the scattering of plane waves by a dielectric wedge. Correcting surface currents are expanded in a Neumann series of fractional orders to meet the edge condition of static limit〔4〕. For the better converging series, the modified Neumann series satisfying the static limit edge condition and the radiation condition are suggested here for the surface currents having two different wave numbers of air and dielectric〔4〕. This representation gives accurate solutions over the whole region including the grazing incidence of the plane waves upon the dielectric wedge of large permittivities.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.884-890
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• 1996

We have investigated a structural change of Si(100)-($2 \times 1$)-Sb surface caused by atomic hydrogen adsorption at room temperature using time-of-flight impact collision ion scattering spectroscopy (TOF-ICISS) and low energy electron diffraction (LEED). We found that when atomic hydrogen adsorbs on the Si(100)-($2 \times 1$)-Sb surface, (1) the partial desorption of Sb atoms from the Si(100) surface occurs even at room temperature, (2) the rest Sb atoms are displaced from their original positions and form an almost two-dimensional layer with dispersive distribution of Sb atoms, and (3) the structural transformation into the Si(100)-($1 \times 1$)-H periodicity is induced by the formation of the $1 \times 1$-H dihydride phase on the Si substrate.

• 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.

• Journal of the Optical Society of Korea
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• v.20 no.5
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• pp.563-566
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• 2016

We report a theoretical research for the condition of electromagnetic shield breaching when a narrow aperture is punctured in thin metal film. To calculate electromagnetic field transmission through a narrow slit, a Rayleigh wave expansion has been applied for free standing, thin metal film. We found that the DC electric field allows perfect transmission when the length of the slit is infinite, regardless of the other geometrical factors such as slitwidth and thickness. Slitwidth dependent transmission spectra as a function of frequency shows a cutoff frequency that decreases almost linearly to the slitwidth, giving that almost successful shielding is only possible when the slitwidth is smaller than 1 micron.

• Advances in nano research
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• v.5 no.3
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• pp.253-260
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• 2017

We report a simple eco-friendly process for the synthesis of gold nanoparticles (AuNPs) using aqueous extract from Coffea Arabica fruit. The formation of AuNPs was confirmed using absorption spectroscopy and scanning electron microscopy images. FT-IR analysis demonstrates the major functional groups present in Coffee Arabica fruit extract before and after synthesizing AuNPs. The Face Center Cubic (FCC) polycrystalline nature of these particles was identified by X-Ray diffraction (XRD) analysis. Taking into account the contribution of the biomass surrounding the AuNPs, dynamic light scattering (DLS) results revealed an average particle size of ~59 nm.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.661-666
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• 1995

The surface structure of the adsorption site for the identification of active sites involved in the Ziegler-Natta catalyst was studied by surface science techniques. As an example of a real catalyst, TiCl3 single crystals were prepared in a gradient furnace designed for this study and characterized by Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED) under ultrahigh vacuum condition. The chlorine covered Ti (0001) surface was employed as a model catalyst for the study of Ziegler-Natta catalyst. The diffuse LEED (DLEED) technique for the surface structural determination was applied to this disordered chlorine adsorbed on Ti (0001) surface. The diffuse scattering intensities were measured by a TV-computer method using a low light level video camera. From an analysis of two catalyst systems, the informations for the surface structure of the model catalyst surfaces were derived.

• Journal of the Optical Society of Korea
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• v.6 no.3
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• pp.76-82
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• 2002

For dielectric gratings on a flat metal surface, photonic band gaps created by Brags scattering of surface plasmon polaritons are observed. The observation result that directly images this gap is compared with that predicted by a numerical model based on a plane wave expansion. Consistency between the experimental and numerical results is also confirmed by comparison with the well-known calculation method of diffraction, the rigorous coupled wave analysis method.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.486-490
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• 2013

A portable infrared laser transmitter delivering a highly uniform detectable beam was demonstrated. It incorporates a flexible beam shaper, comprising a perforated diffuser sheet in conjunction with a pinhole. The beam shaper plays the prominent role of flexibly tailoring the incoming light via both scattering and diffraction, in order to equalize the effective beam width over a long distance. The intensity profile of a generated beam was practically observed, demonstrating that a substantially uniform beam of 70-cm width was achieved for a given threshold detection level, with an average deviation of 6% over a range of 600 m.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.81-81
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• 2003

The stochiometric mixture of evaporating materials for the CuGaSe$_2$ single crystal thin films were prepared from horizontal furnace. Using extrapolation method of X-ray diffraction patterns for the polycrystal CuGaSe$_2$, it was found tetragonal structure whose lattice constant no and co were 5.615$\AA$ and 11.025$\AA$, respectively. To obtains the single crystal thin films, CuGaSe$_2$ mixed crystal was deposited on throughly etched GaAs(100) by the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were 61$0^{\circ}C$ and 45$0^{\circ}C$ respectively, and the growth rate of the single crystal thin films was about 0.5${\mu}{\textrm}{m}$/h. The crystalline structure of single crystal thin films was investigated by the double crystal X-ray diffraction(DCXD). Hall effect on this sample was measured by the method of van der pauw and studied on carrier density and mobility depending on temperature. From Hall data, the mobility was likely to be decreased by pizoelectric scattering in the temperature range 30K to 150K and by polar optical scattering in the temperature range 150K to 293K. The optical energy gaps were found to be 1.68eV for CuGaSe$_2$ single crystal thin films at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation then the constants in the Varshni equation are given by a=9.615$\times$ 10$^{-4}$ eV/K, and $\beta$=335K. From the photocurrent spectra by illumination of polarized light of the CuGaSe$_2$ single crystal thin films. We have found that values of spin orbit coupling ΔSo and crystal field splitting ΔCr was 0.0900eV and 0.2498eV, respectively. From the PL spectra at 20K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be 0.0626eV and the dissipation energy of the acceptor-bound exciton and donor-bound exciton to be 0.0352eV, 0.0932eV, respectively.