• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05a
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• pp.96-100
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• 2003

평면형 자심재료용으로 응용하기 위한 Mn-Zn 페라이트에서 저손실 조성의 전자기적 특성과 분위기 조건에 따른 특성변화를 관찰하였다. $Fe_{2}O_{3}$ : MnO : ZnO 의 물비가 53 : 36 : 11 일 때, 가장 우수한 특성을 나타내었으며, $SiO_{2}$와 CaO는 입계 저항층 형성을 통한 손실은 감소시키고, 이로 인해 성능지수는 증가하여 100kHz ~ 200kHz 범위에서 최대값을 나타내어 전자기적 효율이 극대화되었다. 산소분압의 제어는 승온과정부터 산소분압을 제어시켜주어야만 Zn-loss 현상의 증가와 $Fe^{2+}$이온 농도의 감소 및 $Fe^{2+}-Fe^{3+}$ 이온간의 호핑(hoping)현상 등에 의한 손실을 최소화 할 수 있으며, 높은 투자율을 얻을 수 있었다. 그리고 소결 또는 냉각 중 평형 산소분압이 유지되지 못하면 다량의 결함이 출현하게 되고, 특히 $600^{\circ}C$이하에서 스피넬 상의 분해-산화반응이 일어나면서 미세구조 상에 결함으로 남게 되어 전자기적 특성이 저하되었다.

• 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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• 2003.05e
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• pp.23-26
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• 2003

The flat transformer, typically, has a number of parallel single turn secondary windings. Each secondary winding is coupled to the same primary winding. Therefore, the current in each secondary winding is equal to the ampere-turns in the primary winding, and to each other. These characteristics are particularly advantageous where parallel rectifiers are used. The windings share the current equally, with no need for ballast resistors or other added components. In this study, the ferrite magnetic core samples of Mn-Zn system for the Flat transformer are manufactured and the electrical and magnetic characteristics of its tested. The density of sample FO2-2 sintered at $1350^{\circ}C$ is $4.00kg/m^3$, which shows the good microstructural state. The initial permeability and saturation flux density of FO2 at room temperature is 2700 and 510mT, individually. The power loss of FO2 samples at 250kHz have been ranged $350kW/m^3$ to $80kW/m^3$ with temperature. And the minimum power loss of sample FO2-2 showed at $70^{\circ}C$, which property seems very positive to apply for a flat transformer.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.211-213
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• 2003

무전극 램프에서 유도 결합형 플라즈마가 많이 사용되는데, 코일의 권선수나 주파수에 의해 전기적 특성의 변화가 크다. 따라서, 기존의 환형 무전극 형광램프에 사용되는 ferrite core나 coil을 새롭게 적용하기 위하여 투자율이 2000인 Mn-Zn ferrite를 사용하여 주파수별로 coil의 권선수를 변화시키며 전기적 특성을 측정하여 기존의 무전극 램프와 비교하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.543-545
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• 2003

무전극 램프에서 유도 결합형 플라즈마가 많이 사용되는데 코일의 권선수나 주파수에 의해 전기적 특성의 변화가 크다. 따라서, 기존의 환형 무전극 형광 램프에 사용되는 ferrite core나 coil을 새롭게 적용하기 위하여 투자율이 2000인 Mn-Zn ferrite를 사용하여 주파수별로 coil의 권선수를 변화시키며 전기적 특성을 측정하여 기존의 환형 무전극 형광램프와 비교하였다.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.60-64
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• 2003

유도결합형 플라즈마를 이용하는 무전극 형광램프는 소프트 페라이트를 이용하여 방전을 유도하며, 페라이트의 주파수나 온도 특성이 안정하면, 공심 솔레노이드코일을 사용하였을 때보다 램프전력이 더 효율적이 된다. 페라이트의 형상과 코일의 권선수는 코일의 임피던스, 인덕턴스, Q-factor에 직접적으로 영향을 주며, 감은 위치에 변화에 의해서도 그 값들이 변할 수 있다. 따라서, 본 논문에서는 전구형 무전극 형광램프의 방전에 중요한 역할을 하는 안테나에 대한 실험 결과로서 Mn-Zn 페라이트를 이용한 솔레노이드 코일에 주파수와 코일의 권선수를 변화시켜 코일의 전기적 특성을 조사하였다. 임피던스 특성은 주파수가 증가함에 따라 증가하였으며, 코일의 권선수가 14회일 때, 기존 램프의 안테나와 비슷한 $324[\Omega]$을 나타내었으나, Q-factor는 코일의 권선수가 증가할 수 록 감소하였으며, 기존 램프의 안테나와 많은 차이를 보였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.211-214
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• 2004

The advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours and is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. 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

• Journal of the Korean Magnetics Society
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• v.25 no.3
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• pp.83-86
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• 2015

Nowadays the weapon systems are employed air bursting munition (ABM) as smart programmable 40 mm shells which have been developed in order to hit the target with programmed munition that can be air burst after a set distance in the battlefield. In order to improve the accuracy of such a bursting time, by measuring the speed of the munition from the barrel, weapon systems calculate the exact time of flight to the target and then the time information must be inputted to the munition. In this study, we introduce a device capable of detecting a shot at K4 40 mm automatic grenade. The shot is composed of a rotating copper band to convert linear motion into rotary motion when it passes through the barrel, the steel section is exert the effect of fragment and aluminum section to give fuze information. The aluminum section was used to detect munition using eddy current method. To measure muzzle velocity by means of non-contact method, two eddy current probes separated 10 cm was employed. Time interval between two eddy current probe detection times was used as muzzle velocity. The eddy current probe was fabricated U-shape Mn-Zn ferrite core with enamelled copper wire, and 200 kHz alternating current was used to detect inductance change. Measured muzzle velocity using the developed sensor was compared to the Doppler radar system. The difference was smaller than 1%.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.3
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• pp.54-60
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• 2001

A newly designed inductive micro displacement detecting system is presented. The proposed inductive system consists of driving coils, position-detecting coils, cores, and closed-loop formed magnetic blocks. The cores and magnetic blocks are made of Mn-Zn ferrite. When AC sine wave is applied to the driving coils, the time derivative flux is generated within the system, and then induced voltages arise in the position-detecting coils according to the core\`s position. Putting the cores to be moved proportionally to the input displacement, the induced voltage is proportional to input displacement. The parameters that affect the system characteristics are turn ratio, air-gap size, excitation frequency, overlap area, load resistance, capacitance effect, and so forth. Based on the experimental results, the system parameters are selected in such a way as to have high sensitivity ad stable responses. The sensitivity of the proposed inductive displacement-detecting system is greater than 2800mV.V-1mm-1 and the linearity error is below $\pm$0.10% in the range of $\pm$200㎛.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.552-559
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• 2004

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The ring-shaped electrodeless lamp is intended as a high efficiency replacement for the incandescent reflector lamp in many applications. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. 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 optical characteristics were measured luminance and a temperature and an optical spectrum distribution for 10 min in a one minute interval at the same time. With a goal of finding alternative materials, we show measurement results of electrical characteristics of a ring-shaped electrodeless fluorescent lamp as a function of frequency and the number of coil turns using a highly permeable($\mu$$_{r}$(equation omitted) 2,000) Mn-Zn ferrite. These results are compared with those of conventional ring-shaped electrodeless fluorescent lamp. It is found that the resistance, inductance and impedance are increased while the quality factor decreases as frequency increases.s.