• Journal of the Korean Magnetics Society
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• v.17 no.4
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• pp.156-161
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• 2007

To develop array magnetic sensors, specular-type giant magnetoresistive- spin valve (GMR-SV) film of Glass/Ta(5)MiFe(7)/IrMn(10)NiFe(5)/$O_2$/CoFe(5)/Cu(2.6)/CoFe(5)/$O_2$/NiFe(7)/Ta(5)(nm) was deposited by using a high-vacuum sputtering system. One of 15 way sensors in the area of $8{\times}8mm^2$ was Patterned a size of $20{\times}80{\mu}m^2$ in multilayer sample by Photo-lithography. All of 15 sensors with Cu electrodes were measured a uniform magnetic properties by 2-probe method. The highest magnetic sensitivity of MR and output voltage measured nearby an external magnetic field of 5 Oe were MS = 0.5%/Oe and ${\triangle}$V= 3.0 mV, respectively. An easy-axis of top-free layers of $CoFe/O_2/NiFe$ with shape anisotropy was perpendicular to one of bottom-pinned layers $IrMn/NiFe/O_2/CoFe$. When the sensing current increased from 1 mA to 10 mA, the output working voltage uniformly increased and the magnetic sensitivity was almost stable to use the nano-magnetic devices with good sensitive properties.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1125-1126
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• 2011

고온 초전도 전력기기는 상전도 전력기기에 비해, 중량과 부피가 작고 전력손실이 거의 없어 효율이 높고 대용량기기에 많은 장점을 지니고 있으며 또한 환경 친화적이다. 대형화가 요구되는 선박추진용 모터를 초전도 모터로 사용할 경우 저속 및 고 토크의 모터를 제작할 수 있고, 계자 권선과 전기자 권선을 초전도 선재로 사용함으로써 높은 전류밀도와 고 자장이 가능하여 고효율 및 소형 경량화 등의 장점이 있다. 그러나 전초전도 모터의 경우 얇은 테이프 형태의 초전도 선재의 특성으로 인해 구리선처럼 가공이 힘들고, 선재를 초전도 상태로 만들기 위한 냉각이 필요하다. 이러한 문제점을 해결하기 위하여 본 연구에서는 동기모터와 선형모터를 혼합하여 고정자에 위치한 racetrack type의 전기자 권선뿐만아니라 회전자에 자기장을 발생시키는 계자 권선도 회전자가 아니라 고정자부분에 위치하므로 구조상 견고하고 냉각등에 장점이 있는 호모폴라 모터를 제안하였으며 자기저항의 변화가 작은 구조로 토크 리플이 작으므로 소음과 진동이 적은 모터를 설계하였다. 설계 결과로부터 호모폴라 모터를 제작하였으며 레이스트렉형과 팬케이크 권선의 임계전류등을 측정하였다. 추후 호모폴라 모터의 성능시험을 진행할 예정이다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.961-962
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• 2011

핵자기공명(NMR, Nuclear Magnetic Resonance) 장치의 성능은 자계의 세기와 균일한 정도에 따라 좌우된다. 그리고 균일도를 높이기 위해 자성체를 더하는 작업을 보정(Shimming)이라고 하며 이를 위해서는 기존에 분포하는 자계와 더해지는 자성체에 의해 발생하는 자계의 세기를 부분별로 정확하고 정밀하게 계산하는 것이 요구된다. 하지만 이를 비오-사바르의 법칙(해석해)으로 계산하는 것은 너무 복잡하고 그 대안으로 사용하는 유한요소법 기반의 수치해석 프로그램은 유한요소법 자체가 가진 오차로 인해 정확한 결과를 얻기 어렵다. 따라서 이를 해결하기 위해 가렛(M. W. Garrett)이 제안한 고조파 해석을 Real*16이 적용된 포트란을 사용하여 구하고 그 결과를 해석해의 값 및 수치해석 프로그램 결과와 비교하였다. 이를 통해 자계를 계산함에 있어서 고조파 해석의 타당성을 확인하였다.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1529-1530
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• 2006

현재 한빛 플라즈마에서 운영되고 있는 전자기 진단장치는 정전탐침, 자장탐침 및 반자성루프 둥이 있다. 정전탐침은 고정식, 이동식, 고속주사방식 세 종류의 진단장치가 개발되어 실험에 이용되어 왔는데 비교적 쉽게 많은 종류의 probe와 다양한 probe tip을 구성할 수 있기 때문에 한빛 장치에서 axial 및 azimuthal 방향으로 전자 온도/밀도 및 그들의 분포를 측정하고 있다. 단일탐침에서 사용되던 RF 보상기술을 삼중탐침에서도 적용시켜 RF 보상 삼중탐침을 개발하였다. 기존의 삼중탐침의 경우에는 DC에 대해서는 높은 임피던스로 외부에 부유되어 있지만 RF의 경우에는 외부와 부유되지 않고 낮음 임피던스로 연결되어있는 경우가 많았다. 하지만 RF보상 삼중탐침의 경우에는 RF의 경우에도 충분히 큰 임피던스로 부유되어 있다. 따라서 보다 왜곡되지 않은 측정을 할 수 있다. RF보상 삼중탐침을 이용하여 한빛 Mirror 플라즈마에서 axial 방향으로 Plasma 변수들의 변화를 관찰하면서 기존의 탐침에서 볼 수 얼던 여러 특성을 관찰할 수 있었다.

• Journal of the Korean Magnetics Society
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• v.23 no.3
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• pp.98-103
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• 2013

The magnetic easy axis of the ferromagnetic layer for the dual-type GMR-SV (giant magnetoresistance-spin valve) having NiFe/Cu/NiFe/IrMn/NiFe/Cu/NiFe multuilayer structure controlled by the post annealing treatment. The magnetoresistive curves of a dual-type IrMn based GMR-SV depending on the direction of the magnetic easy axis of the free and the pinned layers are measured by the different angles for the applied fields. By investigating the switching process of magnetization for an arbitrary measuring direction, the optimum annealing temperature having a steady and isotropy magnetic sensitivity of 2.0 %/Oe was $105^{\circ}C$. This result suggests that the in-plane orthogonal magnetization for the dual-type GMR-SV film can be used by a high sensitive biosensor.

• Geophysics and Geophysical Exploration
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• v.12 no.4
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• pp.355-360
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• 2009

This paper presents mobile robot based down-scale mineral resources exploration test system for the USN (Ubiquitous Sensor Network) based exploration. The system emulates the actual exploration environment. Underneath the metal free test plate, a metal object is attached. A magneto-meter mounted mobile robot runs around on the plate to find the metal. The measured magneto-meter values are transferred to the host PC via wireless network. The system enables to improve the reliability of simulation as well as to help efficient exploration system design. Metal-detecting experiments were carried out to illustrate the efficiency of the proposed system.

• Journal of the Korean Magnetics Society
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• v.11 no.2
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• pp.72-77
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• 2001

Top spin valve films with PtMn antiferromagnetic layers were deposited using a multi-target dc magnetron sputtering in (100)Si substrates overcoated with 500 $\AA$ of Al$_2$O$_3$. Firstly, the post-deposition annealing was performed at 270$\^{C}$ in a unidirectional magnetic field of 3 kOe to induce the crystallographic transformation of the PtMn layer from a fcc (111) to a fct (111) structure. Secondly, the spin valve films were annealed without magnetic fields and magnetic properties were measured. In Si/A1$_2$O$_3$ (500$\AA$)/Ta(50$\AA$)NiFe(40$\AA$)/CoFe(17$\AA$)/Cu(28$\AA$)/CoFe (30$\AA$)PtMn(200$\AA$)Ta(50$\AA$) top spin valve samples, the MR ratio decreased slowly with increasing annealing temperature up to 325$\^{C}$. But above 325$\^{C}$, the MR ratio decreased rapidly to 1%, due to a collapse of the exchange coupling between a antiferromagnetic layer and a pinned layer with increasing annealing temperature. Also above 325$\^{C}$, the exchange biased field rapidly decreased and the interlayer coupling field rapidly increased with increasing annealing temperature. A change in the interlayer coupling field was resulted from the increase in interface roughness due to Mn-interdiffusion through the grain boundaries. We confirmed the temperature in changing magnetic properties agreed well with the blocking temperature of PtMn based spin valve structure.

• Journal of Sensor Science and Technology
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• v.10 no.5
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• pp.292-303
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• 2001

This work reports the tunneling effects of the lateral field emitters. Tunneling effect is applicable to the VMFS(vacuum magnetic field sensors). VMFS uses the fact that the trajectory of the emitted electrons are curved by the magnetic field due to Lorentz force. Polysilicon was used as field emitters and anode materials. Thickness of the emitter and the anode were $2\;{\mu}m$, respectively. PSG(phospho-silicate-glass) was used as a sacrificial layer and it was etched by HF at a releasing step. Cantilevers were doped with $POCl_3(10^{20}cm^{-3})$. $2{\mu}m$-thick cantilevers were fabricated onto PSG($2{\mu}m$-thick). Sublimation drying method was used at releasing step to avoid stiction. Then, device was vacuum sealed. Device was fixed to a sodalime-glass #1 with silver paste and it was wire bonded. Glass #1 has a predefined hole and a sputtered silicon-film at backside. The front-side of the device was sealed with sodalime-glass #2 using the glass frit. After getter insertion via the hole, backside of the glass #1 was bonded electrostatically with the sodalime-glass #3 at $10^{-6}\;torr$. After sealing, getter was activated. Sealing was successful to operate the tunneling device. The packaged VMFS showed very small reduced emission current compared with the chamber test prior to sealing. The emission currents were changed when the magnetic field was induced. The sensitivity of the device was about 3%/T at about 1 Tesla magnetic field.

• Journal of the Korean Magnetics Society
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• v.23 no.6
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• pp.193-199
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• 2013

The regional distribution of magnetic isotropy depending on the post annealing condition for the dual-type structure GMR-SV (giant magnetoresistance-spin valve) of NiFe/Cu/NiFe/IrMn/NiFe/Cu/NiFe multilayer was investigated. The rotation of in-plane ferromagnetic layer induced by controlment of the post annealing temperature inside of the vacuum chamber. The magnetoresistive curves of a dual-type IrMn based GMR-SV depending on the direction of the magnetization easy axis of the free layer and the pinned layer are measured by between $0^{\circ}$ and $360^{\circ}$ angles for the applied fields. The optimum annealing temperature having a steady and isotropy magnetic sensitivity of 1.52 %/Oe was $107^{\circ}C$ in the rotational section of $0{\sim}90^{\circ}$. By investigating the switching process of magnetization for an arbitrary measuring direction, the in-plane orthogonal magnetization for the dual-type GMR-SV multilayer can be used by a high sensitive biosensor for detection of magnetized micro-beads.

• Journal of Digital Contents Society
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• v.12 no.1
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• pp.49-55
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• 2011

Because of causing the geometrical transformation of the magnetic field, the patient implementing the fixation using the nonmagnetic metal screw causes the magnetic susceptibility artifact at an image. Thus, in this research, the distortion measure of the image according to the frequency oblique direction conversion tried to be compared in the magnetic susceptibility artifact occurence. First, the itself phantom inserting the nonmagnetic metal screw of the titanium component was made and the region of interest was set up and the frequency oblique direction the anterior - back side was converted to the right-to-left direction in the axial image and a right-to-left was converted to the upper side - bottom side in the coronal plane and the upper - bottom side was converted to the anterior - back side in the sagittal plane and the distortion measure of the region of interest was compared, it observed. In a result, when converting the frequency oblique direction, the distortion difference of the region of interest could be confirmed and it is considered to enhance the diagnostics efficiency changing the oblique direction appropriately.