• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.130-131
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• 2007

본 논문에서는 자기포화특성이 두드러진 매입형 영구자석 동기전동기의 특성해석, 설계 및 제어에 응용할 수 있는 통합변수인 d-q축 쇄교자속(Flux Linkage)의 추출에 대하여 나타낸다. 특히, 영구자석과 전기자전류에 의한 Cross-Magnetization을 고려한 특성을 유한요소법(F.E.M)을 통하여 나타내며, 제작된 시작기 실험을 통하여 제안된 추출기법의 타당성을 나타낸다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1186-1188
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• 2005

본 논문에서는 8극 12슬롯 내전형 BLDC 전동기를 기본 모델로 하고, 이를 자기저항법 및 유한요소법을 이용하여 해석 및 설계를 하고자 한다. 본 논문에서 설계대상으로 하는 내전형 BLDC 전동기는 기존에 사용중인 모델로서, 외부의 고정 전기자는 기존의 모델에 맞도록 외경을 그대로 유지하면서 Teeth 등을 설계변수로 하였고, 내부의 회전 자석계자는 기존에는 페라이트 자석을 사용하였으나 전동기의 성능 향상을 위해서 희토류 자석으로 대체하였다. 그리고 이로인한 고정자의 포화가 일어나지 않도록 최적 설계를 하였다. 유한요소법을 적용하여 자속분포, 코깅 토오크, 토오크 등을 해석하였고, 고정자와 슬롯의 최적화를 통하여 토오크 및 전동기의 성능을 향상시켰다.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.35-37
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• 2015

본 논문은 전력구 내 지중선에서 발생하는 상용주파수(60 Hz) 자기장을 이용한 2 W급 무선전력 수신장치를 제안한다. 제안하는 수신장치는 자성체와 구리도선을 포함하는 수신 코일, 장치의 개폐를 위한 손잡이, 직렬공진회로 및 정류기를 포함하는 부가회로로 구성된다. 수신장치는 3상 지중선 중 하나에 설치되어 전력구 내 조명 및 온습도 센서를 구동하는데 사용 가능하다. 수신장치의 자성체로는 높은 기계적 강도 및 포화 자속밀도를 가지는 규소강판 박편이 사용되었으며, 직렬공진회로를 사용하여 최대전력을 수신하였다. 수신장치의 공진회로는 3 이하의 낮은 공진계수를 가지기에 50 Hz 및 60 Hz 지중선에 범용으로 사용이 가능하다. 사용된 규소강판 및 구리선의 무게와 가격의 곱을 성능지수(Figure of Merit)로 선정하여 이를 최소화하는 설계를 수행하였다. 제작된 시작품의 무게는 약 750 g중으로 2.2 W LED부하 구동이 가능하며, 이때 지중선의 전류는 $100A_{rms}$로 가정하였다.

• Journal of Conservation Science
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• v.16 s.16
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• pp.89-103
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• 2004

Provenance discrimination of sixty four obsidian artifacts found in the Korean Peninsular has been carried out using major elements, minor elements and magnetic properties. Most of obsidians in this study were classified into the subalkaline series based on the contents of $Al_2O_3,\;CaO,\;and\;Na_2O+K_2O$ in samples. Provenance & obsidians were classified into three major groups using major elements and minor elements analyse. This result suggests that there are no correlations among the three groups whose provenances are different. Although the magnetic properties of obsidians do not yield clear groupings according to the archaeological site, the bivariate plot for the magnetic susceptibility and the saturation isothermal remanent magnetization shows a rough correlation with the results of major and minor elements analyses.

• Journal of the Korean Magnetics Society
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• v.10 no.2
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• pp.81-85
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• 2000

Crystallographic and magnetic properties of the Mn-doped orthoferrite LaFe$_{1-x}$Mn$_{x}$ O$_3$(0.0$\leq$x$\leq$O.4) system have been investigated by means of x-ray diffractometry, M ssbauer spectroscopy, vibrating sample magnetometer and super-conducting quantum interference device. The structure of the system was found to be orthorhombic distorted perovskite structure. At room temperature, the M ssbauer spectra for x=0.0 consists of one Zeeman sextets from Fe$^{3+}$ ions at octahedral sites. The M ssbauer spectra of two Zeeman sextets (x$\leq$0.1) change one Zeeman sextets and a paramagnetic doublet (x=0.4). The saturation magnetization increases but the coercivity decreases with increasing x in LaFe$_{1-x}$Mn$_{x}$ O$_3$.

• Journal of the Korean Magnetics Society
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• v.8 no.1
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• pp.6-12
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• 1998

Fe-N(iron-nitrogen) crystal phases were prepared by nitrogen ion implantation into $\alpha$-Fe foil with Plasma Source Ion Implantation (PSII). Ion implantation time of sample is treated 15 minutes(FeN15) and 30 minutes (FeN30). The nitrogen depth profiles measured by Auger electron spectroscopy (AES) were determined to be about 12000 $\AA$ and 4000 $\AA$ for the samples of FeN15 and FeN30, respectively. The results of vibrating sample magnetometer (VSM) show that the saturation magnetization of the samples of as-implanted FeN15 and FeN30 was higher than that of pure $\alpha$-Fe foil, which may be owing to $\alpha$'-$Fe_8N$ or $\alpha$"-$Fe_{16}N_2$ phases. Accordingly this study shows the possibility of the partial formation of $\alpha$' or $\alpha$" phase in iron nitrogen produced by PSII method.II method.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.228-233
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• 2010

The microwave permeability was measured in order to analyze the thickness dependence of loss properties in CoFeHfO thin films with varying thickness of t = 57~1368 nm. A single resonance peak (P1) at 2.95 GHz was appeared in the samples with thickness less than 405 nm, while second resonance peak (P2) at 547MHz was additionally appeared in the samples with thickness greater than 405 nm. The P2 was originated by the angle distribution of the easy axis, which was confirmed from the measured results of the change of imaginary permeability with applied magnetic field in the sample of 1368 nm thickness and low field torque curves. If the second peaks can be reduced by minimizing the angle distribution of the easy axis, the CoFeHfO thin films with thickness greater than 400 nm can be used for the compact microwave devices operated at up to 2 GHz ranges.

• Journal of the Korean Magnetics Society
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• v.16 no.6
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• pp.293-299
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• 2006

Magnetic nanoparticles were prepared by thermal decomposition and adsorbed with lecithin by applying ultrasonic. The size and saturation magnetization of magnetic nanoparticles were observed with different lecithin concentration, and the maximum tolerated dose (HTD) and toxicity of magnetic fluid was investigated through a biological test. The thickness of lecithin-adsorption layer increased non-linearly with increasing amounts of added lecithin, and the desirable adsorption amount was observed in the lecithin concentration of 20%(w/v). The dispersibility and magnetic properties of lecithin-adsorbed magnetic nanoparticles were most excellent when the ultrasonic exposure time was 1.5h. Also, the maximum tolerated concentration with best cell viability was $32{\mu}g/ml$ in vitro test, and lecithin-adsorbed magnetic fluids improved the biocompatibility by 1.2 times compared with bare magnetite fluids in vivo.

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.43-47
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• 2008

[ $ZnO-Bi_2O_3-Al_2O_3-B_2O_3-SiO_2$ ] nano-glass has been prepared by sol-gel method. The mean particle size was 60.3 nm with narrow size distribution. The nano-galss has been used as a sintering aid for the densification of the NiZnCu ferrites. The ferrite was sintered with nano-glass sintering aids at $840{\sim}900^{\circ}C$, 2 h and the initial permeability, quality factor, density, and saturation magnetization were also measured. The initial permeability of 0.5 wt% nano-glass added toroidal sample for NiZnCu ferrites sintered at $900^{\circ}C$ was 193.3 at 1 MHz. The initial permeability and saturation magnetization were increased with increasing annealing temperature. As a result, $ZnO-Bi_2O_3-Al_2O_3-B_2O_3-SiO_2$ nano-glass systems were found to be useful as sintering aids for multilayer chip inductors.

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.14-18
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• 2008

Bismuth-substituted yttrium iron garnet(Bi:YIG) films, which show excellent magnetic and magneto-optical properties as well as low optical losses by optimizing their deposition and post-annealing condition, have been attracting great attention in optical device research area. In this study, the Bi:YIG thick films were deposited with the aerosol deposition method for the final purpose of applying them to optical isolators. Since the aerosol deposition is based on the impact adhesion of sub-micrometer particles accelerated by a carrier gas to a substrate, the flow rate of carrier gas, which is in proportion to mechanically collision energy, should be treated as an important parameter. The Bi:YIG($Bi_{0.5}Y_{2.5}Fe_5O_{12}$) particles with $100{\sim}500$ nm in average diameter were carried and accelerated by nitrogen gas with the flow rate of 0.5 l/min${\sim}$10 l/min. The coercive force decreased from 51 Oe to 37 Oe exponentially with increasing gas flow rate. This is presumably due to the fact that the optimal collision energy results in reduction of impurity and pore, which makes the film to be soft magnetically. The saturation magnetization decreased due to crystallographical distortion of the film with increasing gas flow rate.