• 한국세라믹학회지
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• 제52권2호
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• pp.128-132
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• 2015

In this study, we prepared cadmium phosphate glasses with various compositions, given by $xCdO-(100-x)P_2O_5$ (x = 10-55 mol%), and analyzed their Fourier transform infrared spectra, dissolution rate, thermal expansion coefficient, glass transition temperature, glass softening temperature, and optical band gap. We found that the thermal expansion coefficient and dissolution rate increased while the glass transition temperature and glass softening temperature decreased with increasing CdO content. These results suggest that CdO acts as a network modifier in binary phosphate glass and weakens its structure.

• Electronic Materials Letters
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• 제14권6호
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• pp.733-738
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• 2018

Undoped and Mn-doped $In_2O_3$ films were prepared by radiofrequency magnetron sputtering technique. The effects of Mn doping on the structural and optical properties of as-prepared films were investigated using X-ray diffraction, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. Mn doping can enhance the intensity of (222) peak in Mn-doped $In_2O_3$ thin film, indicating Mn dopant promotes preferred orientation of crystal growth along (222) plane. XPS analyses revealed that the doped Mn ions exist at + 2 oxidation states, substituting for the $In^{3+}$ sites in the $In_2O_3$ lattice. UV-Vis measurements show that the optical band gap $E_g$ decreases from 3.33 to 2.87 eV with Mn doping in $In_2O_3$, implying an increasing sp-d exchange interaction in the film. Our work demonstrates a practical means to manipulate the band gap energy of $In_2O_3$ thin film via Mn impurity doping, and significantly improves the photoelectrochemical activity.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1388-1390
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• 2007

This paper investigates how various concentrations of lithium ion influence on crystallization of MgO in thin films formed by spin coating and an the discharge characteristic in a flat fluorescent lamp structure. The XRD results indicate $Li^+$ ion enhances the growth of MgO crystal in a spin coated thin film. The discharge property with the $Li^+$ ion doped MgO films show the lithium ion in MgO film clearly reduce the initial discharge voltages of test devices. Interestingly, the test panels with various doped MgO film have somewhat higher static memory margin of than that of pure-MgO owing probably to the pore structure of spin coated MgO films. The CL spectra, which confirm that the doping creates defects energy levels in the band gap of MgO, show the $F^+$ center is the main defects in doped MgO films.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.6038-6053
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• 2017

In this study, we propose an automatic melody extraction algorithm using deep learning. In this algorithm, feature images, generated using the energy of frequency band, are extracted from polyphonic audio files and a deep learning technique, a convolutional neural network (CNN), is applied on the feature images. In the training data, a short frame of polyphonic music is labeled as a musical note and a classifier based on CNN is learned in order to determine a pitch value of a short frame of audio signal. We want to build a novel structure of melody extraction, thus the proposed algorithm has a simple structure and instead of using various signal processing techniques for melody extraction, we use only a CNN to find a melody from a polyphonic audio. Despite of simple structure, the promising results are obtained in the experiments. Compared with state-of-the-art algorithms, the proposed algorithm did not give the best result, but comparable results were obtained and we believe they could be improved with the appropriate training data. In this paper, melody extraction and the proposed algorithm are introduced first, and the proposed algorithm is then further explained in detail. Finally, we present our experiment and the comparison of results follows.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1890-1892
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• 2005

Recently, high luminance and high efficiency were realized in OLEDs with multilayer structure including emitting materials such as metal-chelate complexes. New luminescent materials, [2- (2-hydroxyphenyl)-quinoline] (Zn(HPB)q), [(1,10-phenanthroline)- (8-hydroxyquinoline)] Zn(Phen)q was synthesized. Zn-Complexes have low molecular compound and thermal stability. The ionization potential(IP) and electron affinity(EA) of Zn-complexes were measured by cyclic-voltammetry(CV). The fundamental structure of the OLEDs was $ITO/{\alpha}$-NPD/Zn-Complex/Al and then we made device structure rightly in energy band gap. We using Zn(Phen)q as emitting layer and Zn(HPB)q as electron transport layer. We measured current density-voltage, luminance-voltage characteristics.

• Smart Structures and Systems
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• 제29권3호
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• pp.457-473
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• 2022

A high-frequency vibration control method is proposed in this paper for Pumped Storage Power Plants (PSPPs) using Eddy Current Tuned Mass Damper (EC-TMD), based on which a new type of EC-TMD device is designed. The eddy current damper parameters are optimized by numerical simulation. On this basis, physical simulation model tests are conducted to compare and study the effect of structural performance with and without damping, different control strategies, and different arrangement positions of TMD. The test results show that EC-TMD can effectively reduce the control effect under high-frequency vibration of the plant structure, and after the additional damping device forms EC-TMD, the energy dissipation is further realized due to the intervention of eddy current damping, and the control effect is subsequently improved. The Multi-Tuned Mass Damper (MTMD) control strategy broadens the tuning band to improve the robustness of the system, and the vibration advantage is more obvious. Also, some suggestions are made for the placement of the dampers to promote their application.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.906-909
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• 2006

The secondary electron emission coefficient $({\gamma})$ of the cathode is an important factor for improving the discharge characteristics of AC-PDPs because of its close relationship to discharge voltage. In AC-PDPs, MgO is most widely used as a surface protective layer. In this experimental, we have investigated the electronic structure of the energy band structure of the MgO layer responsible for the high ${\gamma}$. The MgO layers have been deposited by electron beam evaporation method, where the $O_2$ partial pressures have been varied as 0, $5.2{\times}10^{-5}$ torr, $1.0{\times}10^{-4}$ torr, and $4.1{\times}10^{-4}$ torr, in this experiment. It is noted that work function that is energy gap between surface and first defect level of MgO layer has the lowest value for the highest O2 partial pressure of $4.1^{\ast}10^{-4}$ Torr.

• 한국전기전자재료학회논문지
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• 제13권5호
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• pp.437-443
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• 2000

In this study several lanthanide complexes such as Eu(TTA)$_3$(Phen), Tb(ACAC)$_3$-(Cl-Phen) were synthesized and the white-light electroluminescence(EL) characteristics of their thin films were investigated where the devices having structures of anode/TPD/Tb(ACAC)$_3$(Cl-Phen)/Eu(TTA)$_3$(Phen)/Alq$_3$or Bebq$_2$/cathode and the low work function metal alloy such as Li:Al was used as the electron injecting electrode(cathode). Device structure of glass substrate/ITO/TPD(30nm)/Tb(ACAC)$_3$(Phen)(30nm)/Eu(TTA)$_3$(Phen)(6nm)/DCM doped Alq$_3$(10nm)/Alq$_3$(20nm)/Li:Al(100nm) was also fabricated and their EL characteristics were investigated where Eu(TTA)$_3$(Phen) and DCM doped Alq$_3$were used as red light-emitting materials. It was found that the turn-on voltage of the device with non-doped Alq$_3$was lower than that of the devices with doped Alq$_3$and the blue and red light emission peaks due to TPD and Eu(TTA)$_3$(Phen) with non-doped Alq$_3$were lower than those with DCM doped Alq$_3$Details on the white-light-emitting characteristics of these device structures were explained by the energy and diagrams of various materials used in these structure where the energy levels of new materials such as ionization potential(IP) and electron affinity(EA) were measured by cyclic voltametric method.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.592-602
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• 2021

Thorium compounds have attracted immense scientific and technological attention with regard to both fundamental and practical implications, owing to unique chemical and physical properties like high melting point, high density and thermal conductivity. Hereby, we investigate the mechanical and thermodynamic stability and report on the structural, electronic and magnetic properties of new silicon-doped cubic ternary thorium phosphides ThSi_xP_1-x (x = 0, 0.25, 0.5, 0.75 and 1). The first-principles density functional theory procedure was adopted within full-potential linearized augmented plane wave (FP-LAPW) method. The exchange and correlation potential terms were treated within Generalized-Gradient-Approximation functional modified by Perdew-Burke-Ernzerrhof parameterizations. The proposed compounds showed mechanical and thermodynamic stable structure and hence can be synthesized experimentally. The calculated lattice parameters, bulk modulus, total energy, density of states, electronic band structure and spin magnetic moments of the compounds revealed considerable correlation to the Si substitution for P and the relative Si/P doping concentration. The electronic and magnetic properties of the doped compounds rendered them non-magnetic but metallic in nature. The main orbital contribution to the Fermi level arises from the hybridization of Th(6d+5f) and (Si+P)3p states. Reported results may have potential implications with regard to both fundamental point of view and technological prospects such as fuel materials for clean nuclear energy.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.170.1-170.1
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• 2016

$Bi_2Te_3$ has long been studied for its excellent thermoelectric characteristics. Recently, this material has been known as a topological insulator (TI). The surface states within the bulk band gap of a TI, which are protected by the time reversal symmetry, contribute to the conduction at the surface, while the bulk is in insulating state. In contrast to the bulk defects tuning the chemical potential to the Dirac energy, the native defects near the surface are expected not to change the shape of the Fermi surface and the related spin structure. Using scanning tunneling microscopy (STM), we have systematically characterized surface or near surface defects in p- and n- doped $Bi_2Te_3$, and identified their structure by first principles calculations. In addition, bias-polarity dependences of STM images revealed the electron donor/acceptor nature of each defect. A detailed theoretical study of the surface states near the Dirac energy reveals the robustness of the Dirac point, which verifies the effectiveness of the disturbance on the backscattering from various kinds of defects.