• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.822-829
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• 2002

This paper deals with the distribution characteristics of the current density and axial magnetic flux density for each slits made on the contact electrode in the vacuum interrupter with axial magnetic field type using 3-dimension finite element analysis. It has been known that the presence of an axial magnetic field parallel to the current flow in the arc plasma can increase the high current breaking capacity of vacuum interrupter by carrying out the arc plasma from constricted mode to diffusion mode. The axial magnetic field is created of itself by current flow in the segments of coil electrode behind the contact electrode. The analyzed results show that if the slits are made in the contact electrode, they can increase the current density and axial magnetic flux density in the contact electrode surface and at the gap distance, which is due to decrease the effect of eddy currents flowing in the contact electrode. The phase shift due to eddy currents, defined 3s time difference between the maximum value of current and axial magnetic field, is decreased still more by increasing the number of slits made in the contact electrode at the center point of gap distance. These results demonstrate that 3-dimension finite element analysis has a great deal of merits in the development and evaluation of new electrode at the design of vacuum interrupter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.411-414
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• 2009

It has been investigated for the film uniformity and deposition rate of a-C:H films on glass substrate and polymeric materials in the presence of the modulated crossed magnetic field. We used Plasma CVD, i.e, using a crossed electromagnetic field, for uniform depositing thin film. The optimum discharge condition has been discussed for the gas pressure, the magnetic flux density and the distance between substrate and electrodes, As a result, it is found that the optimum discharge conditions are $CH_4$ concentration $CH_4$=10 %, modulated magnetic flux density B=48 Gauss, pressure P=100 mTorr, discharge power supply voltage V=l kV under these experimental conditions. By using these experimental condition, it is possible to prepare the most uniform film extends over about 160 mm of the film width. In this study, we deposited a-C:H thin film on glass substrate, and have a plan that using this condition, study depositing a-C:H thin film on polymeric substrate in next studies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.284-287
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• 2001

Multi-pole anisotropic Sr-fertile sintered magnets has been studied by powder injection molding under applied magnetic field. The orientation of anisotropic Sr-ferrite powders higher than 80% during injection molding is achieved at the following conditions; apparent viscosity lower then 2500 poise in 1000 sec$\^$-1/ shear rate and applied magnetic field higher then 4 kOe. For the high fluidity and strength of injection molded compact, and the effective binder removal without defects during solvent extraction and thermal debinding, the optimum multi-binder composition is paraffin wax(PW)/carnauba wax(CW)/HDPE = 50/25/25 wt%. The rate of binder removal is proportional to the mean particle size of Sr-ferrite powders whereas it is inversely proportional to the content of Sr-ferrite powders and the sample thickness. The high magnetic properties of Sr-ferrite sintered magnets are; 3.8 kG of remanent flux density, 3.4 kOe of intrinsic coercivity, and 1.2 kG of surface flux density (1-mm-thick) in the direction of applied magnetic field.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.460-467
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• 2002

This paper deals with the distribution characteristics of the current density and axial magnetic flux density on the vacuum interrupter with axial magnetic field type using 3 dimension finite element analysis. An axial magnetic field parallel to the current flow in the arc column can improve the current breaking capacity of vacuum interrupter by affecting the arc mode. The axial magnetic flux density on the contact electrode surface is analyzed by inputting external current as a function of the transient time for sine half wave. And it also is analyzed within the gap distance of the contact electrode. The peak value of current but is decreased with the descending current on the contact electrode surface and within the gap distance of the contact electrode. The residual magnetic field is generated on the contact electrode surface and within the gap distance in the instant of zero current, which is due to the influence of eddy currents. The phase shift due to eddy currents, defined as time difference between the maximum value of current and axial magnetic field, is about 1ms in the center point of gap distance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.782-787
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• 2004

Superconducting flux flow transistor (SFFT) is based on a control of the Abrikosov vortex flowing along a channel. The induced voltage by moving of the Abrikosov vortex in an SFFT is greatly affected by the thickness, the width, and the length of channel. In order to fabricate a reproducible channel in the SFFT, we studied the variation of the critical characteristics of ${YBa}_2{Cu}_3{O}_7-\delta(YBCO)$ thin films with the etching time using ICP (Inductively coupled plasma) system. From the simulation, it was certified that the vortex velocity was increased in a low pinning energy at channel width 0,5 mm. The surfaces of YBCO thin film were etched by ICP etching system. We observed the etched channel surfaces by AFM (Atomic Force Microscope) and measured the critical current density with etching time. As a measured results, the etching thickness of channel should be optimized to fabricated a flux flow transistor with specified characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.33-34
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• 2006

The effects of Ba and Ce addition has been investigated in YBCO prepared by trifluoroacetate (TFA) metalorganic depostition (MOD) method. Precursor solutions with cation ratios of Y:Ba:Cu:Ce = 1:2+x:3:x (x = 0, 0.05, 0.1 and 1.5) have been prepared by adding an excess amount of cerium and barium. Coated film was calcined at lower temperature and conversion heat treatment at temperature of $780{\sim}810^{\circ}C$. It has been shown that the critical current (Ic) of YBCO film was degraded by doping of Ba and Ce atoms. But Ic was increased as the amount of doped Ba and Ce content increased from 5 % to 15 %. It was observed that there was little increase of a flux pinning force with Ba and Ce addition in YBCO film prepared by TFA-MOD process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.259-262
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• 2003

Superconducting flux flow transistor(SFFT) is based on a control of the Abrikosov vortex flowing along a channel. The induced voltage by moving of the Abrikosov vortex in SFFT is greatly affected by the thickness and width, of channel. In order to fabricate a reproducibility channel in SFFT, we have researched the variation of the critical characteristics of YBCO thin films with the etching time using ICP(Inductively coupled plasma) system. It was certified that the velocity of vortex decreased with increasing the width of channel and was saturated faster in low bias from a simulation. An etching mechanism of YBCO thin films by ICP system was also certified by AFM(Atomic Force Microscope) and by measuring the critical current density with etching time. As measurement result, we could analyze that we should optimize the etching thickness of channel part to construct a flux flow transistor with desired characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.587-590
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• 2003

The first attention in designing a transformer for low temperature rise should be to reduce losses. Leakage inductance and temperature rise are two of the more impotent problems facing the magnetic core technology of today's high frequency transformers. Excessive leakage inductance increases the stress on the switching transistors and limits the duty-cycle, and excessive temperature rise can lead the design limitation of high frequency transformer with high current. The flat transformer technology provides a very good solution to the problems of leakage inductance and thermal management for high frequency power. The critical magnetic components and windings are optimized and packaged within a completely assembled module. The turns ratio in a flat transformer is determined as the product of the number of elements or modules times the number of primary turns. The leakage inductance increase proportionately to the number of elements, but since it is reduced as the square of the turns, the net reduction can be very significant. The flat transformer modules use cores which have no gap. This eliminates fringing fluxes and stray flux outside of the core. The secondary windings are formed of flat metal and are bonded to the inside surface of the core. The secondary winding thus surrounds the primary winding, so nearly all of the flux is captured.

• Membrane Journal
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• v.25 no.5
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• pp.391-397
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• 2015

The porous support polyvinylidene fluoride (PVDF) with a salting out based on the hollow fiber membrane polyethyleneimine (PEI) and polyvinylsulfonic acid (PVSA) by coating with by phase separated and pressurization (PSP) method to produce a multilayer membrane. The resulting membranes were characterized under the various conditions, such as the heat treatment temperature, coating concentration, feed concentration, cross-linking time and cross-link agent concentration in terms of flux and rejection rate for NaCl 100 ppm solution at 4 atm. The best results were PEI 20,000 ppm and PVSA 1,000 ppm, PEI 15% with a 2% malic acid aqueous solution coated by PSP method the hollow fiber membrane heat-treated for 1 minute showed flux 24.3 LMH, the rejection of 82.1%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.531-534
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• 2004

In Recent, it became necessary to develope the technology about electrodeless fluorescent lamp according to demand of the electodeless fluorescent lamp system that used higher efficiency and advantage of long-lifetime. Especially, in the electordeless fluorescent lamp which used H-mode, efficiency of lamp is decided from matching parameter of antena and inverter. So it is of the utmost importance to design antena and inverter Therefore, this paper used a transformer principle for efficiency rising of electrodeless fluorescent lamp and interpreted an equivalent circuit, used an impedance analyzer in order to confirm a performance enhancement of lamp along design of antenna, and confirmed parameter characteristic of R, L, C, Z, Q-factor along a change of magnetic flux density. Also, this paper confirmed a luminance characteristic of electordeless lamp along parameter change with measuring optical characteristic along a change of magnetic flux density