• Journal of Sensor Science and Technology
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• v.16 no.3
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• pp.234-239
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• 2007

Crystallographically {h00}-oriented $0.94(Bi_{0.5}Na_{0.5})TiO_{3}-0.06BaTiO_{3}$ (0.94BNT-0.06BT) ceramics was prepared by the Reactive Templated Grain Growth (RTGG) method using the $Bi_{4}Ti_{3}O_{12}$ template. The sheets prepared by tape-casting of slurries containing the templates and starting materials are cut, laminated, and pressed. Then burn-out and sintering was conducted. Also, to compare with the 0.94BNT-0.06BT ceramics prepared by the RTGG method another 0.94BNT-0.06BT ceramics was prepared by the solid-state method. In the optimum of this experiments range, the degree of orientation of the 0.94BNT-0.06BT ceramics prepared by the RTGG method was texture fraction${\approx}92%$ and the piezoelectric constant($d_{33}$) and coupling factor($k_{p}$) was obtained to $d_{33}{\approx}205{\;}pC/N$, $k_{p}{\approx}0.33%$, respectively.

• Carbon letters
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• v.15 no.2
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• pp.77-88
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• 2014

Double walled carbon nanotubes (DWCNTs) are considered an ideal model for studying the coupling interactions between different concentric shells in multi-walled CNTs. Due to their intrinsic coaxial structures they are mechanically, thermally, and structurally more stable than single walled CNTs. Geometrically, owing to the buffer-like function of the outer tubes in DWCNTs, the inner tubes exhibit exciting transport and optical properties that lend them promise in the fabrication of field-effect transistors, stable field emitters, and lithium ion batteries. In addition, by utilizing the outer tube chemistry, DWCNTs can be useful for anchoring semiconducting quantum dots and also as effective multifunctional fillers in producing tough, conductive transparent polymer films. The inner tubes meanwhile preserve their excitonic transitions. This article reviews the synthesis of DWCNTs, their electronic structure, transport, and mechanical properties, and their potential uses.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.384-393
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• 2012

Railroad signaling systems perform controlling the distance and routes between trains. Signaling methods on the wayside are to control passively the train speed by using signal flags which are installed on the wayside. ATS(Automatic Train Stop) device is used as the signaling method on the wayside in Korea. The ATS device is assistance equipment of engineers. Signal information is transmitted by combining mutual inductance between the wayside transmitter and on-board receiver. The wayside transmitter performs changing oscillation frequency according to the signal information. The on-board receiver performs controlling the train by receiving the frequency. Currently, the oscillation frequency on the on-board receiver is 78[kHz] in case of normal state. When the on-board receiver is over the wayside transmitter, the oscillation frequency is changed by capacitors of the wayside transmitter according to signal flags. In case of changing the oscillation frequency, the waveform is modified in the wayside transmitter and on-board receiver. This phenomenon is that other signals or communication frequency are included. In this paper, electric model between the wayside transmitter and on-board receiver is suggested and frequency response in the wayside transmitter and on-board receiver including other signals is estimated by the coupling coefficient. Also, the value of coupling coefficient is proposed to exclude other signals and demonstrated by using Matlab and PSpice program.

• Journal of Power Electronics
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• v.16 no.2
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• pp.805-814
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• 2016

Electric-field coupled power transfer (ECPT) systems have been proposed as an alternative wireless power transfer (WPT) technology in recent years. With the use of capacitive plates as a coupling structure, ECPT systems have many advantages such as design flexibility, reduced volume of the coupling structure and metal penetration ability. In addition, wireless communications are effective solutions to improve the safety and controllability of ECPT systems. This paper proposes a power and signal shared channel for electric-field coupled power transfer systems. The shared channel includes two similar electrical circuits with a band pass filter and a signal detection resistor in each. This is designed based on the traditional current-fed push-pull topology. An analysis of the mutual interference between the power and signal transmission, the channel power and signal attenuations, and the dynamic characteristic of the signal channel are conducted to determine the values for the electrical components of the proposed shared channel. Experimental results show that the designed channel can transfer over 100W of output power and data with a data rate from 300bps to 120 kbps.

• Journal of Information Display
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• v.10 no.2
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• pp.92-95
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• 2009

Highly efficient blue and white phosphorescent organic light-emitting diodes (PHOLEDs) with an exciton-confining structure were investigated in this study. Effective charge confinement was achieved by stacking two emitting layers with different charge-transporting properties, and blue PHOLEDs with a maximum luminance efficiency of 47.9 lm/W were developed by using iridium(III) bis(4,6-(difluorophenyl) pyridinato-N,C2')picolinate (FIrpic) as an electrophosphorescent dopant. Moreover, when the optimized green and red emitting layers were sandwiched between the two stacked blue emitting layers, white PHOLEDs (WOLEDs) with peak external and luminance efficiencies of 19.0% coupling technique.and 54.0 lm/W, respectively, were obtained without the use of any out-coupling technique.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.315-322
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• 2016

Room acoustic properties of coupled rooms connected by an aperture has been analyzed using statistical acoustic model based on the diffused sound field assumption, which has limitation in dealing with the parameters such an room geometries and non uniform absorptivity of the boundary surfaces. In order to overcome these difficulties the acoustic diffusion model has been introduced, by which distribution of the acoustic energy density can be analyzed for various shapes and wall absorptivity. In this study acoustic properties of coupled rooms connected by an aperture(e.g. door) is analyzed using acoustic diffusion equation, which is solved numerically. The mean energy densities of two rooms obtained by the diffusion model are compared with those from the statistical model. The results show good agreement for various coupling aperture sizes and absorption coefficients. For a limiting case when the partition wall is substituted by an aperture and the two rooms eventually forms a single room, results of coupled room analysis using diffusion model show good agreement with those of a single room.

• Journal of the Korean Chemical Society
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• v.24 no.3
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• pp.233-238
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• 1980

It was observed that the magnetic moment for iron in $[(DPGH)_2FeO_2Fe(DPGH)_2]$, the oxygenation product of a octahedral iron(Ⅱ) complex, $[Fe(DPGH)_2(NH_3_2]$, decreases with decreasing temperature from ${\mu}$ = 3.60 B.M (Bohr Magneton) per iron at $298^{\circ}$K down to ${\mu}$ = 1.65 B.M per iron at $4.2^{\circ}K$. This observation may be explained by a weak antiferromagnetic coupling between two iron(Ⅲ) atoms of intermediate spin state (S = 3/2) in the molecule with the coupling constant $J = -l cm^{-1}$.

• Journal of Magnetics
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• v.8 no.1
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• pp.18-23
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• 2003

In our previous work, microstructure and magnetic properties of two-phase exchange-coupled $Sm_2Fe_{15}Ga_2C_{x}$/$\alpha$-Fe nanocomposites have been investigated by means of x-ray diffraction, transmission electron microscopy and magnetization measurement. It was found the exchange coupling between the magnetically hard phase $Sm_2Fe_{15}Ga_2C_{x}$ and the magnetically soft one ${\alpha}$-Fe results in an enhancement of the remanence. The sizes of crystallites of both phases are, however much larger than the Block domain-wall width of the magnetically hard phase. This microstructure gives rise to a concave demagnetization curve and consequently reduces the maximum energy Product. In order to improve their magnetic properties, a few Percent of Zr, which may be effective to refine the microstructure through rapid quenching, was introduced into the nanocomposites. The addition of Zr was found to improve the magnetic properties significantly, Under optimum heat-treatment conditions, the remanence, coercivity and maximum energy Product increase from 0.65 T, 0.48 T and 50 kJ/$m^{3}$ for the Zr-free sample to 0.72 T, 0.77 T and 71.6 kJ/$m^{3}$ for the 1 at.% Zr-containing one, respectively, The improvements of magnetic properties are due to the refinement of microstructure by the addition of Zr.

• Membrane and Water Treatment
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• v.3 no.1
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• pp.1-23
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• 2012

The coupling of anaerobic biological process and membrane separation could provide excellent suspended solids removal and better biomass retention for wastewater treatment. This coupling improves the biological treatment process while allowing for the recovery of energy through biogas. This review gives a basic description of the anaerobic wastewater treatment process, summarizes the state of the art of anaerobic membrane bioreactors (AnMBRs), and describes the current research trends and needs for the development of AnMBRs. The research interest on AnMBR has grown over the conventional anaerobic processes such as upflow anaerobic sludge blanket (UASB). Studies on AnMBRs have developed different reactor configurations to enhance performances. The AnMBR performances have achieved comparable status to other high rate anaerobic reactors. AnMBR is highly suitable for application with thermophilic anaerobic process to enhance performances. Studies indicate that the applications of AnMBR are not only limited to the high strength industrial wastewater treatment, but also for the municipal wastewater treatment. In recent years, there is a significant progress in the membrane fouling studies, which is a major concern in AnMBR application.

• International Journal of Aerospace System Engineering
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• v.2 no.1
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• pp.43-46
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• 2015

Aeroelastic gust response analysis plays an important role in design of aircrafts. For gust response analysis, frequency domain aerodynamics method has been typically used with generalized aerodynamic influence coefficient matrices at various reduced frequencies. However, it cannot be applied to the aeroservoelastic analysis, such as gust alleviation control. Time-domain state space (SS) models must be built. It attacks little attention that gust response analysis relies on continuous gust time-domain input signal in terms of its PSD function. The aim the current study is to provide a reduced-order modeling (ROM) method based on CFD to model gust responses for continuous gust responses for continuou gust inputs in time domain. The paper analyzed the gust response of AGARD445.6 wing subjected to the Dryden gust with ROMs and compared the difference between the rigid structure and elastic one. The results demonstrate that structure elastic effect effect should be considered in the design of aircraft.