• Journal of IKEEE
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• v.22 no.4
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• pp.1206-1209
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• 2018

Single-layer winding configuration in a 12-slot 10-pole Permanent Magnet Synchronous Motor (PMSM) has been adopting in electrical power steering (EPS) systems to get the high fault tolerance capability of the motor. However, the motor with single-layer winding has magnetic circuit saturations in the teeth, which deteriorates its performance. In this paper, we propose asymmetric teeth widths to get over the demerit, and analyze the effect of the teeth width ratio variations on the performances of the PMSM. As a result, we suggest the most valuable teeth width ratio for designing the PMSM with a single-layer winding configuration.

• Progress in Medical Physics
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• v.19 no.4
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• pp.269-275
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• 2008

Although MR imaging is generally applicable to depict knee joint deterioration it, is sometimes occurred to mis-read and mis-diagnose the common knee joint diseases. In this study, we employed magnetization transfer ratio (MTR) method to improve the diagnosis of the various knee joint diseases. Spin-echo (SE) T2-weighted images (TR/TE 3,400-3,500/90-100 ms) were obtained in seven cases of knee joint deterioration, FSE T2-weighted images (TR/TE 4,500-5,000/100-108 ms) were obtained in seven cases of knee joint deterioration, gradient-echo (GRE) T2-weighted images (TR/TE 9/4.56/$50^{\circ}$ flip angle, NEX 1) were obtained in 3 cases of knee joint deterioration, In six cases of knee joint deterioration, fat suppression was performed using a T2-weighted short T1/tau inverse recovery (STIR) sequence (TR/TE =2,894-3,215 ms/70 ms, NEX 3, ETL 9). Calculation of MTR for individual pixels was performed on registration of unsaturated and saturated images. After processing to make MTR images, the images were displayed in gray color. For improving diagnosis, three-dimensional isotropic volume images, the MR tristimulus color mapping and the MTR map was employed. MTR images showed diagnostic images quality to assess the patients' pathologies. The intensity difference between MTR images and conventional MRI was seen on the color bar. The profile graph on MTR imaging effect showed a quantitative measure of the relative decrease in signal intensity due to the MT pulse. To diagnose the pathologies of the knee joint, the profile graph data was shown on the image as a small cross. The present study indicated that MTR images in the knee joint were feasible. Investigation of physical change on MTR imaging enables to provide us more insight in the physical and technical basis of MTR imaging. MTR images could be useful for rapid assessment of diseases that we examine unambiguous contrast in MT images of knee disorder patients.

• Journal of the Korean Magnetics Society
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• v.7 no.5
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• pp.265-273
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• 1997

The MR ratios and the exchange biasing field and interlayer coupling field were investigated in $Ni_{91}Fe_{19}/Co_{90}Fe_{10}/Cu/Co_{90}Fe_{10}/NiO$ spin-valve sandwiches grown on antiferromagnetic NiO films as a function of the NiO thickness, the thickness of Cu and pinning layer $Co_{90}Fe_{10}$. The spin-valve sandwiches were deposited on the Corning glass 7059 by means of the 3-gun dc and 1-gun rf magnetron sputtering at a 5 mtorrpartial Ar pressure and room temperature. The deposition field was 50 Oe. The MR curve was measured by the four-terminal method with applied magnetic soft bilayer [NiFe/CoFe] (90$\AA$) decreased dramatically to less than 10 Oe when the NiFe/CoFe bilayer used an NiFe bilayer thicker that 20$\AA$. So NiFe layer improved the softmagnetic properties in the NiFe/CoFe bilayer. The GMR ratio and the magnetic field sensitivity of the spin-valve film $Ni_{91}Fe_{19}(40{\AA})/Co_{90}Fe_{10}(50{\AA}) /Cu(30{\AA})/Co_{90}Fe_{10}(35{\AA})/NiO(800{\AA})$ was 6.3% and about 0.5 (%/Oe), respectively. The MR ratio had 5.3% below an annealing temperature of 20$0^{\circ}C$ which slowly decreased to 3% above 30$0^{\circ}C$. The large blocking temperature of the spin-valve film was taken (as being) due to the good stability of the NiO films. Thus, the spin-valve films with a free NiFe/CoFe layer clearly had a high large GMR output and showed a effective magnetic field sensitivity for a suitable spin-valve head material.

• Clinical and Experimental Pediatrics
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• v.48 no.11
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• pp.1232-1238
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• 2005

Purpose : Though more than 15 years have passed after introduction of Lorenzo's oil therapy in X-linked adrenoleukodystrophy(ALD), its efficacy is still fully not known. In patients who already have neurologic symptoms, most reports indicate that the neurologic disability continues to increase. We evaluated its efficacy in X-linked ALD patients. Methods : Four patients who were treated with Lorenzo's oil for at least 12 months were enrolled from 1996 to 2003. During treatment, changes of neurologic symptoms, brain magnetic resonance imaging(MRI) findings, and serum saturated very long-chain fatty acid(C26:0) were assessed. Results : Two patients with childhood cerebral ALD had progression of neurologic symptoms and MRI lesions during treatment. One asymptomatic patient developed childhood cerebral ALD after six year treatment of Lorenzo's oil. One "Addison only" patient remained neurologically intact after three years. During Lorenzo's oil therapy, serum C26:0 levels which had increased at diagnosis decreased in all four patients. Conclusion : Treatment with Lorenzo's oil did not prevent disease progression in childhood cerebral ALD patients who were already symptomatic. Long term follow up will be needed in asymptomatic ALD including "Addison only" to reveal the efficacy of Lorenzo's oil.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.3
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• pp.163-172
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• 1989

In order to study spatial variability of soil physical properties accross the land-partitioned boundary on Hwadong silt clay loam soil (Fine clayey, mixed, mesic family of Aquic Hapludalfs), all measured data were analyzed by means of kriging, fractile diagram, smooth frequency distribution, and autocorrelation. Sampling for soil particle size distribution analysis was made at 225 intersections of $15{\times}15$ grid with 10m interval. Field capacity, bulk density and saturated hydraulic conductivity were measured in situ at 594 intersections of $33{\times}18$ grid with 2.5m interval in only $6,000m^2$ reselected from $22,500m^2$ of sampling area for particle size distribution analysis. Sampled or measured soil depths were 0 to 10cm 25 to 35cm and 50 to 60cm at each intersections. The results are summarized as follows: 1. The coefficient of variance (CV) of various physical properties ranges from 4.8 to 128.8%. Saturated hydraulic conductivity is classified into the high variation group with CV greater than 100%, while the low variation group with CV smaller than 10% consists of bulk density. Other properties belong to the medium variation group with CV between 10 and 100%. 2. The appropriate number of soil samples for the determination of various physical properties with error smaller than 10% are calculated as one for bulk density, six for field moisture capacity, 16 for silt, 19 for clay, 69 for sand and 686 for saturated hydraulic conductivity. 3. Smooth frequency distribution and fractile diagram show that saturated hydraulic conductivity is in lognormal distribution while other physical properties are in normal distribution. 4. Serial correlation analysis reveals that the soil physical properties have spatial dependence between two nearest neighbouring grid points. Autocorrelation analysis of physical properties measured between the serial grid points in the direction of south to north following section boundary shows that the zone of influence showing stationarity ranges from 7.5 to 40m. In the direction of east to west across section boundary, the autocorrelogram of many physical properties shows peaks with the periodic interval of 30m, which are similar to the partitioned land width. This reveals that the land-partitioned boundary causes soil variability.

• Journal of the Korean Magnetics Society
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• v.13 no.1
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• pp.1-5
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• 2003

Magnetic and structural properties of $(CoFe_2O_4)_{1-x}(Y_3Fe_5O_{12})_x$ powders (0 $\leq$ x $\leq$ 1) grown by a conventional ceramic method were investigated using X-ray diffractormeter (XRD), scanning electron microscopy (SEM), Mossbauer spectroscopy and vibrating sample magnetometer (VSM). The XRD results for the powders annealed at 120$0^{\circ}C$ indicated that no other peak was observed except for the ones from cobalt ferrite and the garnet powder. SEM micrographs indicated that cobalt ferrite and garnet powders were aggregated and completely formed together. It was hard to identify which part of the powders was the garnet or the cobalt ferrite. Mossbauer spectra for powders grown separately and mixed mechanically consisted of sub-spectra of cobalt ferrite and garnet, however, powders annealed together had an extra sub-spectrum, which was related with the interaction between iron ions at the grain surfaces of cobalt ferrite and the garnet: cobalt ferrite and garnet particles were located very closely. The value of the saturation magnetization measured by a VSM as a function of composition ratio agreed very well with the ones based on the theoretical calculation.

• Resources Recycling
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• v.12 no.6
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• pp.13-18
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• 2003

The initial NiCuZn synthetic ferrite were acquired from thermally decomposing the metal nitrates Fe($NO_3$)$_3$ㆍ$9H_2$O, Zn($NO_3$)$_2$ㆍ$6H_2$O, Ni($NO_3$3)$_2$ㆍ $6H_2$O and Cu(NO$_3$)$_2$ㆍ $3H_2$O at 1$50^{\circ}C$ for 24 hours and was calcined at $500^{\circ}C$. Each of those was pulverized for 3 and 9 hours in a steel ball mill and was sintered between $700^{\circ}C$ and $1,000^{\circ}C$ for 1 hour, and then their microstructures and magnetic properties were examined. We could make the initial specimens chemically bonded in liquid at the temperature as low as $150 ^{\circ}C$, by using the melting points less than $ 200^{\circ}C$ of the metal nitrates instead of the mechanical ball milling, then narrowed a distance between the particles into a molecular level, and thus lowed sintering temperature by at least $200 ^{\circ}C$ to $300^{\circ}C$ Their initial permeability was 50 to 490 and their saturation magnetic induction density and coercive force 2,400G and 0.3 Oe to 1.2 Oe each, which were similar to those of NiCuZn ferrite synthesized in the conventional process.

• Progress in Medical Physics
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• v.18 no.1
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• pp.35-41
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• 2007

In this work practical considerations of a pulsed arterial spin labeling MRI are presented to reliable multi-slice perfusion measurements In the human brain. Three parameters were considered in this study. First, In order to improve slice profile and Inversion efficiency of a labeling pulse a high power Inversion pulse of adiabatic hyperbolic secant was designed. A $900^{\circ}$ rotation of the flip angle was provided to make a good slice profile and excellent Inversion efficiency. Second, to minimize contributions of a residual magnetization be4ween Interleaved scans of control and labeling we tested three different conditions which were applied 1) only saturation pulses, 2) only spotter gradients, and 3) combinations of saturation pulses and spotter gradients Applications of bo4h saturation pulses and spoiler gradients minimized the residual magnetization. Finally, to find a minimum gap between a tagged plane and an imaging plane we tested signal changes of the subtracted image between control and labeled Images with varying the gap. The optimum gap was about 20mm. In conclusion, In order to obtain high quality of perfusion Images In human brain It Is Important to use optimum parameters. Before routinely using In clinical studios, we recommend to make optimizations of sequence parameters.

• Journal of the Korean Magnetics Society
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• v.15 no.3
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• pp.186-190
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• 2005

The $Al_{0.2}CoFe_{1.8}O_4$ ferrite films and powders were prepared by the sol-gel method. The crystallographic and magnetic properties of the samples were examined with annealing temperature by X-ray diffraction, $M\ddot{o}ssbauer$ spetroscopy and vibrating sample magnetometry. The powder samples showed the presence of spinel structure at annealing temperatures above 673 K, while the film samples indicated the spinel structure above 873 K, also the particle size increased with rising annealing temperatures. The $M\ddot{o}ssbauer$ spectra of $Al_{0.2}CoFe_{1.8}O_4$ powder annealed above 873 K could be fitted as the superposition of two Zeeman sextets due to ferrimagnetic phase. And the spectra of annealed at 673 K exhibited the superposition of ferrimanetic and paramagnetic phase and those of annealed at 473 K showed only a paramagnetic phase. The magnetic behaviour of powders appeared that the coercivity increased until annealed at 673 K but decreased above this temperature. The coercivity of the film samples decreased from 1.084 kOe at 873 K to 0.540 kOe at 1073 K with increasing annealing temperatures.

• Resources Recycling
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• v.8 no.4
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• pp.45-56
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• 1999

The purpose of tlus sludy was to preparc raw material powder for Mn-Zn iclrile, h m mined mill scale and fero-Mn, usins a co-spray roasting process The mill scale and ferra-Mn uscd in this raalins process was rcf~nedb y mesn-ns of a slxc~apl rxcss ~nvolvinm~a te~ialsc ontalning imp~u-ltleso r less than 100 pprn In this study an effeclive spray roaster system. wllich produces fme complex oxide powder, collects produccd ~owder.,m d prcvel~tse ~~llssiooifi HCI gas. was also manufactured. By means of spray~ngp urifcd raw malerial solu~lionl nln a manufacued high tcmpervture rumace. &-ferrite powder and a comnpleu o ~ d e powder of Fe,O; and M,x203 were manufactured. The chmcterlstics of the composllion. surface urca, and p'miicle size dismbulion or the produced powder were exmined. ptoduced powdcr was then ~ m e dwi tli ZnO powder. aid olher addilives of defined cornposnion, and Mn-Zn femite cares werc praiuccil by meuns of Sorlning and closely controlled sintering processes. The magpelic p~oprlieso f c olo~ss, initlal permeability. mauin~u~mnn agnehc flux. coz~civcr orcc and residual magnccic flux for the above cores we,= measured, and fmm Il~ase I-csulls the eflicacy of lhe co-spray roasling pncess to pl.ellare raw material powder lor Mn-Zn ferntc was established