• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.506-508
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• 2001

The ferrite plating with applying power ultrasound waves of 19.5 kHz and 600W enabled us to encapsulate entirely MnZn ferrite cores for transformers with Ni$\sub$x/Zn$\sub$y/Fe$\sub$3-x-y/O$_4$coating. Supplying a NH$_4$OH solution during the plating broke the limit of the solubility of Ni ions to ferrite-plated films. The electrical resistivity of the NiZn ferrite coating increased with increasing the Ni and Zn content, reaching 2.3${\times}$10$\^$5/Ωcm at the composition of Ni$\sub$0.24/Zn$\sub$0.30/Fe$\sub$2.46/O$_4$. The saturation magnetization was 540 emu/㎤. As a result, the MnZn ferrite cores were successfully encapsulated with the NiZn ferrite coatings for an insulation layer.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.474-480
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• 2001

In this paper a low signal reduction communication system that does not use the communication line but power line is presented It will be very useful for an information-oriented society with tele-metering and home automation. The conventional system has a difficulty in transmitting information due to decreasing communication voltage. The proposed system employs a special type switching amplifier system which has a low inner resistance and uses high efficient ferrite core in coupling circuit. This new system is proposed to reduce the loss of conductor load and coupling circuit in a PLC system.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.613-616
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• 1998

In this paper, a model of a Eddy-current probe coil with a ferrite core in the presence of a half-space with a layer is developed. The half-space with a layer is accounted for by computing the appropriate Green's function by using Bessel transforms. Upon introducing equivalent Amperian currents within a core to explain effect to a impedance change in the coil due to a (ferrite) core, we derive a volume integral equation, The integral equation is transformed via the method of moments into a vector-matrix equation, which is then solved using a linear equation solver. Through the above processing, we computed impedance value in a Eddy-current probe coil due to a conductivity change of layer.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.146-152
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• 2003

The waste ferrites from magnetic core manufacturing process were used to $CO_2$gas decomposition to avoid the greenhouse effects. The waste ferrites are the mixed powder of Ni-Zn and Mn-Zn ferrites core. In the reduction of ferrites by 5% $H_2/Ar$ mixed gas, the weight loss of ferrites was about 14~16wt%. After the$CO_2$gas decomposition reaction, the weight of the reduced ferrites was increased up to 11wt%.$CO_2$gas was decomposed by oxidation of Fe and FeO in reduced compound and the phase of the waste ferrite was changed to spinel structure. A new technique capable of$CO_2$decomposition as low cost process through utilizing waste ferrite was development.

• Journal of the Korean Magnetics Society
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• v.23 no.3
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• pp.94-97
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• 2013

Orthogonal fluxgate sensor was fabricated with cylinder-shaped NiZn ferrite core, Cu wire through the core and pickup coil wound on the core, and the bias current effect on the output sensitivity of it was investigated. The output ($$\sim_\sim$$ sensitivity) of the sensor was largely dependent on the operation frequency, and the tendency of sensor output was similar to that of the impedance of pickup coil. The maximum output was obtained by adding the DC bias current of which value was over 50% of the excitation current. The output was saturated when the DC bias current was larger than 50% of the excitation current.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.606-609
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• 1995

Ferrite cores are often magnetized under DC-biased field because they have been intensively used in electronic circuits such as an inverter circuit and a switching regulator circuit. Thus we investigated the effects of DC-biased field on magnetic properties in the frequency range of DC-100kHz for two kinds of ferrite cores, TDK PC38 and TDK $H_{3}S$, which have different shapes of B-H loop from each other. The magnetic loss per cycle, W/f, in the $H_{3}S$ core decreased with increasing the strength of DC-biased field, although W/f in the PC38 core increased monotonically with DC-biased field. The observed decreasing tendency differs from the previous result for Si-Fe and ferrite cores, and can be attributed to decrease in eddy current loss as well as that in hysteresis loss.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.5
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• pp.28-35
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• 2000

In this paper, we design a ring inductor using the ferrite core to denoise the EMI(Electromagnetic Interference) for facsimile. The EMI for facsimile is radiated from the signal line of PSTN(Public Switching Telephone Network) between facsimile and PSTN. We denoise the radiated noise by inserting a ferrite core(Ni-Zn) between facsimile and PSTN. Even though we may denoise the radiated noise using two or more than two ferrite cores, we only concentrate on denoising EMI by adjusting number of turns of one ferrite core since it gives economical gain. As a result of measuring EMI using the designed inductor with 4 turns inserted in the line connected between facsimile and PSTN, the value of radiated emission is reduced below 30 dB$\mu$V/m.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.2
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• pp.61-66
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• 2003

The electromagnetic properties and thermal behavior of Mn-Zn ferrite cores used for the blocking filter in he Power Line Communication(PLC) application were investigated as the function of additives. The highest density and permeability of 4.98 g/㎤) and 8,221 respectively were obtained to the specimen with composition of MnO 24 mol%, ZnO 25 mol% and Fe$_2$O$_3$ 51 mol% added MnO$_3$ 400 ppm, SiO$_2$ 100 ppm and CaO 200 ppm since the uniform grains were organized and the microstructures were compacted through reduction of pores. The permeability was increased up to 13,904 as temperature of specimen increased to 11$0^{\circ}C$, however, it was decreased precipitously under 100 over 11$0^{\circ}C$. The exothermic behavior was observed in the frequency range from 1 kHz to 1 MHz that the maximum temperature of specimens became 102$^{\circ}C$ at 1 MHz. In the consequence, the Mn-Zn ferrite core developed by this research will maintain the stable electromagnetic properties since the temperature of ferrite core rose to 93$^{\circ}C$ in the range of 10 kHz to 450 kHz bandwidth qualified for PLC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.68-71
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• 2002

The electromagnetic properties and thermal behavior of ferrite cores used in the blocking filter for PLC were investigated as a function of additives. The highest density of 4.98 $g/cm^2$ and permeability of 8221 were obtained to the specimen added $MoO_3$ 400 ppm, $SiO_2$ 100 ppm and CaO 200 ppm since the microstructures were compacted through reduction of pores in the specimen. The permeability was increased up to 13094 at $110^{\circ}C$ with increasing temperature of specimen, however, it was decreased precipitously to under 100 over $110^{\circ}C$. The exothermic behavior was observed that the temperature of specimens became $102^{\circ}C$ at 1MHz. In the consequence, the ferrite core developed by this research will maintain the stable electromagnetic properties since the temperature of ferrite core rose to $93^{\circ}C$ in the range of 10kHz to 450kHz bandwidth qualified for PLC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.53-57
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• 2006

In this paper, maxwell 3D finite element analysis program (Ansoft) was used to obtain electromagnetic properties associated with the coil and nearby structures. The electromagnetic emitting properties were presented by 3D simulation software operated at 250 kHz and some specific conditions. The electromagnetic field in the ferrite core was shown to be high and symmetric. An LS-100 luminance meter and a Darsa-2000 spectrum analyzer were used in the experiment. According to data on the lamp tested using high magnetic field ferrite, the optical and thermal wave fields were shown to be high around the ring-shaped electrodeless fluorescent lamp. The optical or light field was high at the center of the bulb rather than around the ferrite core. The light conditions of the bulb were assumed to be complex, depending on the condition of the filler gas, the volume of the bulb, and the frequency of the inverter. Our results have shown coupling between the gas plasma and the field of the light emitted to be nonlinear.