• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.7
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• pp.304-307
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• 2005

The $In_2S_3\;and\;In_2S_3:Co^{2+}$ thin films were grown by the spray Pyrolysis method. The thin films crystallized into tetragonal structures. The indirect energy band gap was 2.32ev for $In_2S_3\;and\;1.81eV\;for\;In_2S_3:Co^{2+}$ at 298K. The direct energy band gap was 2.67ev for $In_2S_3:Co^{2+}$ thin films. Impurity optical absorption peaks were observed for the $In_2S_3:Co^{2+}$ thin films. These impurity absorption peaks are assigned, based on the crystal field theory to the electron transitions between the energy levels of the $Co^{2+}$ ion sited in $T_{d}$ symmetry. The electrical conductivity($\sigma$), Hall mobility(${\mu}_H$), and carrier concentration (n) of the $In_2Se_3$ thin film were measured, and their temperature dependence was investigated.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.195-201
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• 2005

The $SnS_2,\;SnS_2:Cd$, and $SnS_2:Sb$ single crystals were grown by the chemical transport reaction method. The indirect optical energy band gap was found to be 2.348, 2.345, and 2.343 eV for the $SnS_2,\;SnS_2:Cd$, and $SnS_2:Sb$ single crystals, at 6 K respectively. The direct optical energy band gap was found to be 2.511, 2.505, and 2.503 eV f3r the $SnS_2,\;SnS_2:Cd$, and $SnS_2:Sb$ single crystals, at 6 K respectively The temperature dependence of the optical energy band gap was well fitted by the Varshni equation. Two photoluminescence emission peaks with the peak energy of 2.214 and 1.792 eV for $SnS_2$, 2.214 and 1.837 eV for $SnS_2:Cd$, and 2.214 and 1.818 eV the $SnS_2:Sb$ were observed. The emission peaks were described as originating from the donor-acceptor pair recombinations.

• Smart Structures and Systems
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• v.17 no.3
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• pp.413-429
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• 2016

The recent research on proper orthogonal decomposition (POD) has revealed the linkage between proper orthogonal modes and linear normal modes. This paper presents an investigation into the modal identifiability of an instrumented cable-stayed bridge using an adapted POD technique with a band-pass filtering scheme. The band-pass POD method is applied to the datasets available for this benchmark study, aiming to identify the vibration modes of the bridge and find out the so-called deficient modes which are unidentifiable under normal excitation conditions. It turns out that the second mode of the bridge cannot be stably identified under weak wind conditions and is therefore regarded as a deficient mode. To judge if the deficient mode is due to its low contribution to the structural response under weak wind conditions, modal coordinates are derived for different modes by the band-pass POD technique and an energy participation factor is defined to evaluate the energy participation of each vibration mode under different wind excitation conditions. From the non-blind datasets, it is found that the vibration modes can be reliably identified only when the energy participation factor exceeds a certain threshold value. With the identified threshold value, modal identifiability in use of the blind datasets from the same structure is examined.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.259-262
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• 2003

The surface electronic state of rutile $TiO_2$, which is an oxide semiconductor and has a wide band gap of 3.1 $\sim$ 3.5 eV, was calculated by DV-$X_{\alpha}$ method, which is a sort of the first principle molecular orbital method and uses Hartre-Fock-Slater approximation. The $[Ti_{15}O_{56}]^{-52}$ cluster model was used for the calculation of bulk state and the $[OTi_{11}O_{34}]^{-24}$ model for the surface state calculation. After calculations, the energy level diagrams and the deformation electron density distribution map were compared in both models. As results, it was identified that the surface energy levels are found between the valence and conduction band of bulk $TiO_2$ on the surface area. The energy values of these surface-induced levels are lower than conduction band of bulk $TiO_2$ by 0.1 $\sim$ 1 eV. From this fact, it is expected that the surface energy levels act as donar levels in n-type semiconductor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.84-85
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• 2009

The single crystals of p-$CdIn_2Te_4$ were grown by the Bridgman method without the seed crystal. From photocurrent measurements, it was found that three peaks, A, B, and C, correspond to the intrinsic transition from the valence band states of $\Gamma_7(A)$, $\Gamma_6(B)$, and $\Gamma_7(C)$ to the conduction band state of $\Gamma_6$, respectively. The crystal field splitting and the spin orbit splitting were found to be 0.2360 and 0.1119 eV, respectively, from the photocurrent spectroscopy. The temperature dependence of the $CdIn_2Te_4$ band gap energy was given by the equation of $E_g(T)=E_g(0)$ - $(9.43\times10^{-3})T^2$/(2676+T). $E_g(0)$ was estimated to be 1.4750, 1.7110, and 1.8229 eV at the valence band states of A, B, and C, respectively. The band gap energy of $p-CdIn_2Te_4$ at room temperature was determined to be 1.2023 eV.

• Electrical & Electronic Materials
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• v.9 no.4
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• pp.372-378
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• 1996

The phtoreflectance(PR) spectra of B ion implanted semi-insulating(SI) GaAs were studied. Ion implantation was performed by 150keV implantation energy and 1*10/aup 12/-10$^{15}$ ions/c $m^{2}$ doses. Electronic band structure was damaged by ion implantation with above 1*10$^{13}$ ions/c $m^{2}$ dose. When samples were annealed, " peak was observed at 30-40meV below band gap( $E_{g}$). It should be noted that this energy is close to the ionization energies of S $i_{As}$ , and GeAs in G $a_{As}$ which are also found as impurities in LEC GaAs, it is therefore possible that this feature is related to S $i_{As}$ , or G $e_{As}$ and B ions by implanted defect associated with them. From PR spectra of etched samples which is as-implanted by 1*10$^{14}$ and 1*10$^{15}$ ions/c $m^{2}$ dose, the depth of destroyed electronic band structure was from surface to 0.2.mu.m below surface.nic band structure was from surface to 0.2.mu.m below surface.

• Journal of Power Electronics
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• v.19 no.1
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• pp.44-57
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• 2019

Recently, the use of LLCL filters for grid inverters has been suggested to give better harmonic attenuation than the commonly used L and LCL filters, particularly around the switching frequency. Nevertheless, this filter is mainly designed for constant switching frequency pulse width modulation (CSF PWM) methods. In variable switching frequency PWM (VSF PWM), the harmonic components are distributed across a wide frequency band which complicates the use of a high order filter, including LCL and LLCL filters. Recently, a confined band variable switching frequency (CB-VSF) PWM method has been proposed and demonstrated to be superior to the conventional constant switching frequency (CSF) PWM in terms of switching losses. However, the applicability of LLCL filters for this type of CB-VSF PWM has not been discussed. In this paper, the authors study the suitability of an LLCL filter for CB-VSF PWM and propose design guidelines for the filter parameters. Using simulation and experimental results, it is demonstrated that the effectiveness of an LLCL filter with CB-VSF PWM depends on the parameters of the filters as well as the designed variable frequency band of the PWM. Simulation results confirm the performance of the suggested LLCL design, which is further validated using a lab scale prototype.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.69-74
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• 1998

In order to monitor the tool wear in milling operation, cutting force is measured as the tool wear increased. The digital signal processing methods are used to detect the tool wear . As AR parameter extract the feature of tool wear , it can be used as input parameter of pattern classifier. The FFT monitor the tool wear exactly , but it can not do real time signal processing. The band energy method can be used to real time monitoring of tool wear ,but int can degrade the exact monitoring.

• Rapid Communication in Photoscience
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• v.3 no.3
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• pp.59-60
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• 2014

The trans-$A_2B_2$ porphyrin and Ni-porphyrin derivatives were synthesized by Suzuki coupling of bromoporphyrin with arylborate as a key step. The band gaps of those complexes were measured from their absorption, emission and cyclic voltammetric data. All the LUMO energy level of porphyrin derivatives is lower than that of P3HT, and the HOMO energy level is evaluated higher than the HOMO of PCBM.

• Journal of information and communication convergence engineering
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• v.6 no.4
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• pp.411-416
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• 2008

When compose magnetic field curer by belt and band style and need by magnetic field ripple last month, produce self-discipline roof. Bred in muscle disease (lumbago, backbone disease, corpulence) back. Result that study, manufactured various variableness band style - magnetic field probe firstly. Can establish self-discipline treatment pulse price by disease secondly. Could seek correct variableness band punishment, - magnetic field probe relationship implementation and property in waist, and so on, shoulder, neck, arm, leg, ankle, wrist etc. by third. Could find variableness band style energy value that need in-magnetic field Probe's treatment by fourth. This research could design pulse of self-discipline in band form and apply each according to disease.