• Clean Technology
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• v.16 no.2
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• pp.145-152
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• 2010

Various technical methods are applied for removing water from the water-retaining media, and the energy efficiency is the main concern in those methods. The electroosmotic process is studied as an efficient way for dewatering. An experimental electroosmotic reactor is designed and used for evaluating the effects of operational variables. The operational variables such as the electrical fields and the structure of water-retaining medias were studied. Three different shapes of polarized electric fields in ranges of 0-100 V/cm and 0-10 kHz are used as the source of electric voltage. The effect of electroosmotic process with respect to the structural variation is estimated by filling the electroosmotic reactor with the glass beads in 0.18 mm, 0.35 mm and 1.2 mm in diameters. 6% of water removal is obtained in the simulating electroosmotic reactor of glass beads. The estimated energy consumption in the simulating electroosmotic was 330~490 cal/g-water.

• Journal of the Korean Society of Combustion
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• v.17 no.1
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• pp.37-47
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• 2012

Experimental study on comparison of diffusive-thermal self-excitation with buoyancy-driven one due to accumulation of partially premixed, preheated mixture in front of edge flame was conducted in horizontally and vertically injected laminar free-jet flames with an applied DC electric field of -10 kV. The application of horizontal injection method with the DC electric field to jet flames was experimentally designed to suppress heat-loss-induced self-excitation and thereby to highlight the definite difference between both diffusive-thermal and buoyancy-driven self-excitations with the same order of O(1.0 Hz), in that diffusive-thermal self-excitation has not been so far found experimentally in laminar jet flames. Flame stability maps in vertically and horizontally injected jet flames are presented. The distinct modes of individual self-excitation are shown to be well described by their own phase diagrams. The results show that buoyancy-driven self-excitation due to the accumulation of partially premixed, preheated mixtures in front of edge flame is branched from the buoyancy-induced self-excitation with O(10 Hz) due to a flame flicker. Once the buoyancy-driven self-excitation appears, it suppresses buoyancy-induced as well as diffusive-thermal self-excitation. The key characteristics for individual self-excitation are discussed and their functional dependencies of Strouhal number upon related physical parameters are also presented.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.129-134
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• 2005

Electroplating copper is the important role in formation of 3D stacking interconnection in SiP (System in Package). The I-V characteristics curves are investigated at different electrolyte conditions. Inhibitor and accelerator are used simultaneously to investigate the effects of additives. Three different sizes of via are tested. All via were prepared with RIE (reactive ion etching) method. Via's diameter are 50, 75, $100{\mu}m$ and the height is $100{\mu}m$. Inside via, Ta was deposited for diffusion barrier and Cu was deposited fer seed layer using magnetron sputtering method. DC, pulse and pulse revere current are used in this study. With DC, via cannot be filled without defects. Pulse plating can improve the filling patterns however it cannot completely filled copper without defects. Via was filled completely without defects using pulse-reverse electroplating method.

• Journal of the Korean Magnetics Society
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• v.25 no.1
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• pp.10-15
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• 2015

The model for the magneto-impedance of composite wires composed of highly conductive nonmagnetic metal core and soft magnetic shell was derived based on the Maxwell's equations. The Cu($100{\mu}m$ diameter)/$Ni_{80}Fe_{20}$($15{\mu}m$ thickness) core/shell composite wire was fabricated by electrodeposition. The impedance spectra for the $Cu/Ni_{80}Fe_{20}$ core/shell composite wire were measured in the frequency range of 10 kHz~10 MHz under longitudinal dc magnetic field in 0 Oe~200 Oe. The spectra of complex permeability in circumferential direction were extracted from the impedance spectra by using the derived model. The extracted spectra of complex permeability showed relaxation-type dispersion which is well curve-fitted with Debye equation with single relaxation frequency. By analyzing the magnetic field dependence of the complex permeability spectra, it has been verified that the composite wire has magnetic anisotropy in longitudinal direction and the origin of the single relaxation process is the magnetization rotation in circumferential direction.

• Journal of the Korean Society of Combustion
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• v.16 no.3
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• pp.41-51
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• 2011

In this paper, we describe the behavior of two self-excitations in laminar attached free-jet flames under the influence of DC electric fields, one of buoyancy-driven and the other of diffusion-thermal instability, established from the horizontal and vertical injection. In the horizontal injection with removed buoyancy effect, oscillating flames with the frequency of 1.3 - 7.4 Hz were observed in a certain condition with Lewis number more than unity. On the other hand, it was appeared Lewis number induced self-excitation as well as buoyancy-driven self-excitation in the vertical upward injection with DC electric fields. This behavior had frequency range of 1.6 - 9.4 Hz and was exhibited to attribute the buoyancy effect. Finally, a well-defined division about two self-excitations having similar frequency range is briefly discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.230.2-230.2
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• 2014

스퍼터링 공정은 보통 수백 eV로 가속된 이온에 의한 고체 타겟으로부터 입자의 방출로서 정의할 수 있다. 스퍼터된 입자는 열에너지보다 운동에너지가 크며 박막성장은 저에너지의 입자충격, 불활성 가스이온, 타겟부터 산란된 입자에 의하여 지배된다. 본 연구는 직경 2인치의 원형 Cr 타겟을 셔터를 닫고 예비 스퍼터링 할 때 셔터(SUS 304 0.1t)가 전자기력을 받아서 기계적으로 진동하는 현상을 규명하고자 하였다. 셔터의 하단부를 챔버의 중심축에 고정시켜서 타겟과 평행하도록 수 cm 떨어뜨려서 위치한 뒤 직류 마그네트론 플라즈마를 발생시켰을 때 DC power에 따라서 각각 움직임을 동영상촬영을 진행하였고, 셔터의 중심을 실로 매달아서 자유롭게 움직일 수 있도록 한 뒤 플라즈마가 발생했을 때 기계적인 움직임을 중점적으로 관찰했다. 움직임의 차이를 비교하기 위해서 셔터의 크기를 줄여가며 일정한 DC power에서 실험을 진행했고, 자세한 관찰을 위해서 초고속카메라(210 fps)로 짧은 순간의 변화를 비교했다. 실험조건은 5, 10 mTorr, DC power 30, 40, 50, 70, 100 W, Ar 30 sccm, 셔터의 크기 10, 20, 30, 40, 50, 60 mm로 실시했다. 압력이 낮아질수록, 셔터의 크기가 작을수록, DC power가 커질수록 움직임변화가 커졌고, 진동수가 빨라지는 것을 확인했다. F=qE=ma를 통해서 실험에서 촬영한 동영상을 근거로 거리측정을 통해 실험에서 얼마의 전기장이 인가되어 있는지 예측하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.9
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• pp.1324-1328
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• 2013

The reason of train location detection is generally the train interval control between the railway stations and the train path control in the railway station yard in order to avoid train collision. It is very important to know the train location for shortening the train headway, and improving the efficiency of railway maintenance as well as the safe operation of trains. Therefore, the accurate detection of train location is the prerequisite technology in railway signalling system. The track circuit and the wheel sensor of rolling stock have been used to detect the train location widely in urban railway as well as high speed train. The track circuit is continuously monitored by electrical equipment to detect the absence of the train and the tachometer and encoder is used for the wheel sensor to measure the train speed. But speed sensor failures are frequent due to the extremely harsh operating conditions encountered in rail vehicle. The CBTC(Communication based Train Control) system has been used in urban railway system recently. But the installation of CBTC system is very high and the modification of design is difficult. This paper deals with the feasibility of new train location detection method using magnetic sensors.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.64-72
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• 2002

The use of linear DC motor is spreaded according to industrial development. This study was objected to study the analysis of double side excitation LDM with moving magnet type. In this LDM structure, the mover made use of permanent magnet with six pieces so as to large thrust, the stator was bedded for the multi separated type winding to repress the i개n saturation. Also, double side excitation winding is suppressed to thrust ripple with stratification to zigzag type and designed to production for static thrust. Then it is important to ratio of permanent magnet to winding width at multi separate, this paper analyzed to separate to three pieces of 1:1, 1:0.84 and 1:0.5 with width ratio. The analysis method calculated the parameter useful for permeance and magnetic resistance more than FEM of complicated numerical value analysis. Through manufactured experiment system, measurement result of thrust was almost acquired to constant thrust for all displacement.

• Journal of Biomedical Engineering Research
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• v.32 no.4
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• pp.305-311
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• 2011

For effective stimulation with tDCS, spatial focality of induced electrical field(EF) and current density(CD) is one of the important factors to be considered. Recently, there have been some studies to improve the spatial focality via different types of electrodes and their new configurations: some improvements using ring electrodes were reported over the conventional pad electrodes. However, most of these studies assumed isotropic conductivities in the head. In this work, we have investigated the effect of tissue anisotropy on the spatial focality of tDCS with the 4 + 1 ring electrode configuration via a 3-D high-resolution finite element(FE) head model with anisotropic conductivities in the skull and white matter. By examining the profiles of the induced EF from the head models with isotropic and anisotropic conductivities respectively, we found that the spatial focality of the induced EF significantly drops and get diffused due to tissue anisotropy. Our analysis suggests that it is critical to incorporate tissue anisotropy in the effective stimulation of the brain via tDCS.

• Korean Journal of Optics and Photonics
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• v.11 no.1
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• pp.25-32
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• 2000

Comparisons are made between the first hyperpolarizability $\beta$ of pure N-(4-nitrophenyl)-(L)-prolinol (NPP) and poly (methyl metacrylate) (PMMA) or poly-p-(phenylene terephthalates) (PPT) with NPP side group determined with two different methods, electric-field-induced second-harmonic generation (EFISHG) and hyper-Rayleigh scattering (HRS) methods. Both techniques yield the same values within the experimental errors for pure NPP and NPP-PMMA in 1,1,2,2-tetrachloroethane solution. But the measured results of NPP-PPT polymer in 1,1,2,2-tetrachloroethane solution are showing that the first hyperpolarizability was enhanced with an enhencement of a factor 9.7 in EFISHG and a factor 2.4 in HRS relative to pure NPP. These results indicate that nonlinear optical chromophores organized as side groups of polymers with a rigid backbone contribute coherently to the secondorder nonlinear response of the polymer in the dc electric field as polar polymer chains. hains.