• 환경위생공학
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• 제15권2호
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• pp.102-111
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• 2000

As IR-sensor for detecting pollution material, the iron silicide has a fit band gap, high physicochemical stability at high temperature and good acid resistance. The growing film was formed with the Fe-Si bond and the organic compound because plasma resolved the injected precursors into various active species. In the Raman scattering spectrum, the Fe-Si vibration mode showed at 250 {TEX}$cm^{-1}${/TEX}. The FT-IR peak indicated that the various organic compounds were deposited on the films. The iron silicide was epitaxially grown to β-phase by the high energy of plasma. The lattice structure of films had [220]/[202] and [115]. The thickness of the films increased with the flow rate of silane. But rf-power increased with decreasing the thickness. The optical gap energy and the band gap were shown about 3.8 eV and 1.182∼1.194 eV. The band gap linearly increased and the formula was below: {TEX}$E_g^{dir}${/TEX}= 8.611×{TEX}$10^{-3}N_{D}${/TEX}＋1.1775

• Journal of information and communication convergence engineering
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• 제16권3호
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• pp.197-202
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• 2018

This paper reveals the impact of the insertion of electromagnetic band gap (EBG) structures on the performance of circularly polarized (CP) patch-slot antenna with offset slot. Several optimizations are necessary to precise physical parameters in the aim to fix the resonance frequency at 3.2 GHz. The proposed antenna possesses lightweight, simplicity, low cost, and circular polarization ensured by two feeding sources to permit right-hand and left-hand circular polarization process (RHCP and LHCP). The measured results compared with simulation results of the proposed circularly polarized EBG antenna with offset slot show good band operations with –10 dB impedance bandwidths of 9.1% and 36.2% centered at 3.2 GHz, which cover weather radar, surface ship radar, and some communications satellites bands. Our investigation will confirm the simulation and experimental results of the EBG antenna involving new EBG structures.

• Transactions on Electrical and Electronic Materials
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• 제16권1호
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• pp.5-9
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• 2015

Optical and electrical properties were studied for Antimony doped tin oxide thin films from precursors containing 10, 30, 50, and 70 atom% of Sb deposited on bare sodalime silica, barrier layer coated sodalime silica, and pure silica glass substrates by sol-gel spinning technique. The direct band gaps were found to vary from 3.13~4.12 eV when measured in the hv range of 2.5~5.0 eV, and varied from 4.22~5.08 eV when measured in the range of 4.0~7.0 eV. Indirect band gap values were in the range of 2.35~3.11 eV. Blue shift of band gap with respect to bulk band gap and Moss-Burstein shift were observed. Physical thickness of the films decreased with the increase in % Sb. Resistivity of the films deposited on SLS substrate was in the order of $10^{-2}$ ohm cm. Sheet resistance of the films deposited on barrier layer coated soda lime silica glass substrate was found to be relatively less.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.341-341
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• 2010

Electronic structure of Calix adsorbed on epitaxial graphene (EG) was investigated using high resolution photoemission spectroscopy (HRPES). Increasing the deposition of calix molecule, we found that EG becomes n-type doping using secondary edge measurement (work function change). As we observe bonding nature of O 1s peak, we found that single O 1s peak can be clearly distinguished in the spectra indicating equivalent adsorption state. Finally, we were able to control the band gap of EG using valence band spectra as we change the amount of calix molecule. In this study, we will propose the possibility of band gap modulation of EG using calix molecule.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2511-2513
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• 2007

• Journal of electromagnetic engineering and science
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• 제6권2호
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• pp.98-102
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• 2006

In this paper, we have designed and fabricated the high power amplifier employing PBG(Photonic Band-Gap Structure) to improve the linearity of the amplifier in the millimeter wave band. The fabricated amplifier using MMIC(TGA1073G) has operated about 24 GHz band and the PBG has resulted in 35 dB suppression about 49 GHz where the second harmonic occurs due to the amplifier. As a result, the output power has been 24.43 dBm and 13.2 dBc of the IMD has been improved. Also, the PAE is obtained to 14.96 % of the amplifier employing the PBG structure in Ka band.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.376-376
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• 2010

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 $E_g(T)=E_g(0)-(9.43{\times}10^{-3})T^2/(2676+T)$. $E_g$(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.

• Carbon letters
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• 제28권
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• pp.72-80
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• 2018

In this study, an empirical relationship between the energy band gap of multi-walled carbon nanotubes (MWCNTs) and synthesis parameters in a chemical vapor deposition (CVD) reactor using factorial design of experiment was established. A bimetallic (Fe-Ni) catalyst supported on $CaCO_3$ was synthesized via wet impregnation technique and used for MWCNT growth. The effects of synthesis parameters such as temperature, time, acetylene flow rate, and argon carrier gas flow rate on the MWCNTs energy gap, yield, and aspect ratio were investigated. The as-prepared supported bimetallic catalyst and the MWCNTs were characterized for their morphologies, microstructures, elemental composition, thermal profiles and surface areas by high-resolution scanning electron microscope, high resolution transmission electron microscope, energy dispersive X-ray spectroscopy, thermal gravimetry analysis and Brunauer-Emmett-Teller. A regression model was developed to establish the relationship between band gap energy, MWCNTs yield and aspect ratio. The results revealed that the optimum conditions to obtain high yield and quality MWCNTs of 159.9% were: temperature ($700^{\circ}C$), time (55 min), argon flow rate ($230.37mL\;min^{-1}$) and acetylene flow rate ($150mL\;min^{-1}$) respectively. The developed regression models demonstrated that the estimated values for the three response variables; energy gap, yield and aspect ratio, were 0.246 eV, 557.64 and 0.82. The regression models showed that the energy band gap, yield, and aspect ratio of the MWCNTs were largely influenced by the synthesis parameters and can be controlled in a CVD reactor.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2333-2337
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• 2007

Nanoporous TiO2 and ZrO2 thin films were spin-coated using a surfactant-templated approach from Pluronic P123 (EO20PO70EO20) as the templating agent, titanium alkoxide (Ti(OC4H9)4) as the inorganic precursor, and butanol as a the solvent. The control of the electronic structure of TiO2 is crucial for its various applications. We found that the band gap of the hybrid nanoporous thin films can be easily tuned by adding an acetylacetonestabilized Zr(OC4H9)4 precursor to the precursor solution of Ti(OC4H9)4. Pores with a diameter of 5 nm-10 nm were randomly dispersed and partially connected to each other inside the films. TiO2 and ZrO2 thin films have an anatase structure and tetragonal structure, respectively, while the TiO2-ZrO2 hybrid film exhibited no crystallinity. The refractive index was significantly changed by varying the atomic ratio of titanium to zirconium. The band gap for the nanoporous TiO2 was estimated to 3.43 eV and that for the TiO2-ZrO2 hybrid film was 3.61 eV.

• 한국재료학회지
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• 제4권2호
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• pp.227-232
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• 1994

450KHz 저주파수로 플라즈마 화학증착법을 이용하여 Diamondlike carbon박막을 제작하고 optical band gap, 미소경도, 내부응력 등의 물성에 대하여 13.56MHz의 전원을 사용했을 때보다 optical band gap이 감소하였으며 FT-IR및 CHN분석결과 박막 내의 C-H결합농도와 총 수소의 함량이 크게 감소하는 것으로 밝혀졌다. 또한 저주파수로 DLC 박막을 형성하는 경우 미소경도의 희생없이 내부응력을 크게 줄일 수 있어 기판과의 접착성이 향상될 것으로 기대되었다.