• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.988-990
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• 2003

Disk type Single Phase SRM(Switched Reluctance Motor) can be used axial and radial direction magnetic flux. Therefore, the energy density per unit of volume is high and the axis can be shorter than that of any other motor. In this paper, the flux-linkage was measured according as rotor positions of disk type single phase SRM, which is designed and fabricated in previous studies. From the measured data, we got the magnetization curves, inductance profile, co-energy and torque. Also, we compared the value of the measurement with the value of analysis through 3D FEM simulation.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권5호
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• pp.204-210
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• 2005

Alternating current (AC) losses of two Bi-2223 ([Bi, Pb]: Sr: Ca: Cu: O = 2:2:2:3) tapes [(Tape I, un-twist-pitch) and the other with a twist-pitch of 10 mm (Tape II)] were measured and compared. These samples, produced by the powder-in-(Ag) tube (PIT) method, are multi-filamentary. Also, it's produced by non-twist and different twist pitch (8, 10, 13, 30, 50 and 70 mm). The critical current measurement was carried out under the environment in liquid Nitrogen and in zero-field by 4-probe method. Susceptibility measurements were conducted while cooling in a magnetic field. Flux loss measurements were conducted as a function of ramping rate, frequency and field direction. The AC flux loss increases as the twist-pitch of the tapes decreased, in agreement with the Norris Equation. Neutron-diffraction measurements have been carried out investigate the crystal structure, magnetic structures, and magnetic phase transitions in Bi-2223([Bi, Pb]:Sr:Ca:Cu:O)

• Journal of Magnetics
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• 제4권2호
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• pp.69-72
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• 1999

Magnetic properties and crystallographic structure of e-beam evaporated Co/Cr and Co/Mo multilayer thin films were investigated using VSM and XRD. Co/Cr and Co/Mo multilayer thin films are confirmed as an alternating layered structure. The structure of films with thicker Co layers than Cr and Mo layers are found to be a hcp structure with the c-axis perpendicular to the film plane. The direction of the film plane is the easy magnetization one. There is a no significant difference in shape of hysteresis loops between Co/Cr and Co/Mo multilayer films. It is found that Mo layer is more effective than Cr for preparing Co layer with c-axis normal to the film plane.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
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• pp.101-104
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• 2003

The maximum coercive force of SmCo thin film was obtained at the Sm=28.2% and dc bias field was generated to CoZrNb, soft magnetic thin film, deposited on the SmCo thin film. DC field point having the maximum permeability for CoZrNb was shifted to higher dc field. DC field strength increased as the length of easy direction of magnetization decreased and 60Oe was measured for $3mm{\times}0.5mm$ sample.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.879_880
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• 2009

this paper studies the influence of permanent magnet on the vibration of synchronous motor two PM motors with NdFeB and Ferrite magents which have same Back-EMF and output power have been desined. First, the dynamic simulation is performed with these two motors' parameters. The current waveforms can be evaluated. And then based on the equivalent magnetization current principle, the magnetic force density and force including the tangential and radial direction components can be calculated. According to the relationship between the vibration and radial force, the vibration of these two motors can be predicted. This result will give meaningful advice to the motor design.

• 한국자기학회지
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• 제13권5호
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• pp.193-197
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• 2003

우수한 연자성 특성과 자왜 특성을 동시에 나타내는 철계 아몰퍼스 박막을 이용한 고기능성 센서나 신호처리소자와 같은 자기탄성 디바이스를 구현하기 위해서는 자기이방성의 제어가 필요하다. 본 연구에서는 철계 아몰퍼스 박막의 자기이방성을 제어하기 위해서 바이어스 응력을 이용한 자기이방성제어 방법을 제안하였다. 제안한 방법은 박막의 기판을 굴곡시킨 상태에서 열처리를 실시하여 박막의 응력을 해소하고, 열처리 후 박막기판의 형상을 원상으로 복귀시켜서 박막에 바이어스 응력이 인가되도록 하고, 이 응력에 의해서 박막의 자기이방성이 제어되도록 하는 것이다. 응력을 이용하여 자기이방성을 제어한 박막패턴을 자구의 관찰과 자화곡선의 평가를 고찰한 결과, 제안한 자기이방성 제어방법이 유용함을 알 수 있었다.

• 한국자기학회지
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• 제9권2호
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• pp.91-97
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• 1999

막후 4~80$\mu\textrm{m}$의 YIG(Y3FeO12)막을 GGG(Gd3Ga5O12) 기판 상에 수 종류의 화학조성이 서로 다른 Melt를 사용하여 성장 온도를 변화시키며 LPE(Liquid Phase Epitaxy)법으로 에피탁시 성장시켰다. 제조한 막의 성장속도, 표면 형상, 화학 조성, 격자상수, 포화 자화, 자기공명특성을 조사했다. 기판과 막간의 격자상수의 mismatch Δa, 포화자화 그리고 자기공명흡수반치폭 ΔH는 과냉각온도 ΔT가 증가함에 따라 각각 증가, 감소 및 증가하는 경향을 보였다. 또한, R1값이 작은 Melt를 사용한 경우, 동일한 Δa가 증가하면 막후 방향으로의 응력 분포가 불균일해져 막 내부의 자장이 불균일해지기 때문으로 생각된다. 따라서, 마이크로파 손실이 작은 양질의 마이크로파 소자용 YIG막을 제조하기 위해서는 R1값이 크고 R3값이 작은 Melt를 사용하여 ΔT가 작은 영역에서 막을 성장시켜 ΔT가 작은 영역에서 막을 성장시켜 Δa를 작게 해야만 한다.

• 자원환경지질
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• 제32권2호
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• pp.189-201
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• 1999

Paleomagnetic and rock magnetic investigations have been carried out for the Cretaceous Hanyang Group, exposed in the Yongyang Sub-Basins within the Kyeongsang Basin, eastern South Korea. A total of 452 oriented core samples was drilled from 31 sits for the study. The in-situ site mean direction is more dispersed than the mean direction after bedding correction, indicating that the fold test is positive at 95% confidence level. In addition, the stepwise unfolding of the characteristic remanent magfold test is positive at 95% confidence level. In addition, the stepwise unfolding of the characteristic remanent magnetization reveals that a maximum value of k is observed at 90% unfolding. Furthermore, the rock magnetic investigations and electron microscope observations of the representative samples show that the main magnetic carrier of the Hayang Group is the detrital specular hematite of single and pseudo-single domain sizes with negligible contribution of pigmentary hematite grains. These results collectively imply that the ChRM direction is the primary component acquired at the time of the formation of the strata. Provided the primary nature of the ChRM, a magnetostratigraphic correlation between polarities of the studied formation and the Geomagnetic Time Scale indicates that the Hayang Group in the Yongyang Sub-Basin can be correlated to the Cretaceous Long Normal superchron. The paleomagnetic pole position from this study is significantly different from those of the Hayang group in the Euiseong the Milyang sub-Basins. Rather the paleomagnetic pole position of the Hayang Group of the study area is closer to that of the Quaternary period or present time of the Korean Peninsula. It is hypothesized that the study area might be rotated about 25$^{\circ}$ aticlockwise with respect to the Euiseong and Milyang Sub-Basins after the formation of the strata and aquisition of the ChRM, although there is not enough geologic evidence supporting the rotation hypothesis.

• 한국자기학회지
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• 제12권2호
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• pp.51-56
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• 2002

마그네트론 스퍼터링을 이용하여 퍼멀로이 박막의 제조시 요구되는 자기이방성 조절을 위하여 필요한 조건을 NdFeB자석과 3-D전산모사를 이용하여 평가하였으며, 또한 같은 조건에서 제조된 박막의 특성을 조사하였다. 타겟과 기판과의 거리가 5cm인 경우 타겟 자석과 자기이방성 조절을 위하여 장입된 영구자석의 상호 작용에 의하여 기판에 평행한 자속을 얻기 위한 조건이 전산모사 결과 영구자석간의 거리 변화에 매우 민감하였으며, 최적의 조건의 두 영구자석의 간격이 70mm에서 가장 균질한 자속을 대면적에서 얻을 수 있음이 확인되었다. 투입전력 450 W에서 기판에 장착시킨 NdFeB 자석간 거리(48, 60, 70, 80, 85mm) 를 변화시킨 결과 포화자화 값은 10~12 kG, 보자력은 0.2~1 Oe, 비저항은 20 $\mu$$\Omega$cm의 값을 갖는 퍼멀로이가 제조되었으며, 자기적 이방성은 전산모사의 결과와 일치하였다. 그 결과 자석간의 간격이 70mm에서 제조된 두께 1 $\mu$m 퍼말로이의 유효투자율이 10 MHz에서 2500을 유지하는 결과를 얻었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.188.1-188.1
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• 2015

For present investigation Fe/MgO/Fe/Co multilayer stack is grown on Si substrate using e-beam evaporation in ultrahigh vacuum. This stack is irradiated perpendicularly by 120 MeV $Ag^{8+}$ at different fluences ranging from $1{\times}10^{11}$ to $1{\times}10^{13}ions/cm^2$ in high vacuum using 15UD Pelletron Accelerator at Inter University Accelerator Centre, New Delhi. Magnetic measurements carried out on pre and post irradiated stacks show significant changes in the shape of perpendicular hysteresis which is relevant with previous observation of re-orientation of magnetic moment along the direction of ion trajectory. However increase in plane squareness may be due to the modification of interface structure of stacks. X-ray reflectivity measurements show onset of interface roughness and interface mixing. X-ray diffraction measurements carried out using synchrotron radiation shows amorphous nature of MgO and Co layer in the stack. Peak corresponding body centered Fe [JCPDS-06-0696] is observed in X-ray diffraction pattern of pre and post irradiated stacks. Peak broadening shows granular nature of Fe layer. Estimated crystallite size is $22{\pm}1nm$ for pre-irradiated stack. Crystallite size first increases with irradiation then decreases. Structural quality of these stacks was further studied using transmission electron microscopic measurements. Thickness from these measurements are 54, 36, 23, 58 and 3 nm respectively for MgO, Fe, MgO, Fe+Co and Au layers in the stack. These measurements envisage poor crystallinity of different layers. Interfaces are not clear which indicate mixing at interface. With increase fluence mixing and diffusion was increased in the stack. X-ray absorption spectroscopic measurements carried out on these stacks show changes of Fe valence state after irradiation along with change of O(2p)-metal (3d) hybridized state. Valence state change predicts oxide formation at interface which causes enhanced in-plane magnetization.