• Title/Summary/Keyword: 불연속 자기저항

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A Study on the Structural and Magnetoresistance Properties of Co/Ag Multilayers (Co/Ag 다층박막의 구조 및 자기저항 현상에 관한 연구)

  • 이용규;이성래
    • Journal of the Korean Magnetics Society
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    • v.6 no.2
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    • pp.86-92
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    • 1996
  • The structural, magnetic and magnetoresistance properties of Co/Ag multilayer films prepared by thermal coevaporation were studied. When the Ag layer was $60{\AA}$ thick, the Co layer behaved ferromagnetically even with the thickness of $5{\AA}$. However, when the thickness of Ag layer was $30{\AA}$ and that of Co layer was less than $15{\AA}$ thick, the Co layer became discontinuous and the islands of Co behaved mostly superpararnagnetically. The maximum MR ratio, 6.1% was obtained in the $3000{\AA}\;Ag30{\AA}/Co10{\AA}$ Ag30 A ICo 10 A discontinuous multilayer. Agglomeration of the Co layer was promoted by annealing and hence MR ratio increased when the thickness of Ag layer was thinner than $15{\AA}$. The SiO underlayer enhanced the MR ratio in the $1000{\AA}$ thick multilayer via the layer structure improvement.

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Structural,Magnetic, and Magnetoresistance Behavior of Magnetron Sputtered NiFe/Ag Multilayers under an Ar and $Ar/H_2$ Atmosphere (Ar 및 $Ar/H_2$ 분위기에서 스퍼터 증착한 NiFe/Ag 다층박막의 구조, 자기 및 자기저항 거동에 관한 연구)

  • 서유석;이성래
    • Journal of the Korean Magnetics Society
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    • v.9 no.3
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    • pp.159-165
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    • 1999
  • Structural, magnetic and magnetoresistance behavior of NiFe/Ag multilayers prepared by a magnetron sputter under an Ar and $Ar/H_2$ atmosphere was studied. It was difficult to make a uniform multilayer by using an Ar atmosphere. However, the uniform multilayers could be fabricated by using an $Ar/H_2$ atmosphere. This was thought to be due to decrease in the energy of the sputtered atom and Ar content of the film. Typical magnetoresistance behavior of the discontinuous NiFe/Ag multilayers appeared when the uniform multilayer was formed and annealed. Substrate temperature did not improve the uniformity of the multilayers. Above 20$0^{\circ}C$ of the substrate temperature, the films were almost formed into granular alloys rather than multilayers.

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Shape Design for Improving the Characteristics of Interior PM Synchronous Motor (매입형 영구자석 동기전동기의 특성 향상을 위한 형상설계)

  • Kim, Sung-Il;Lee, Geun-Ho;Hong, Jung-Pyo;Lee, Sung-Ho
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.814-815
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    • 2008
  • 매입형 영구자석 동기전동기의 경우 고효율, 고출력 그리고 넓은 속도 범위와 같은 많은 장점에도 불구하고 상대적으로 큰 코깅토크와 토크 리플로 인하여 정밀한 위치 제어용 전동기로 사용하는데 있어 한계가 있다. 이는 flux barrier와 치 사이의 불연속적인 자기저항의 변화가 주요한 원인 중의 하나로 이를 최소화 할 수 있는 형상 설계가 필요하다. 따라서 본 논문에서는 초기 설계된 매입형 영구자석 동기 전동기의 특성을 향상시키기 위한 형상 설계를 제시하고 실험 결과를 통하여 제안된 설계 방법의 유용성을 증명하고자 한다.

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The Design of Auxiliary-core for Reducing Detent Force (PMLSM의 디텐트력 저감을 위한 보조코어의 설계)

  • Jang, Woo-Sung;Kim, Jee-Hyun;Ahn, Ho-Jin;Jang, Ki-Bong;Kim, Gyu-Tak
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.883_884
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    • 2009
  • PMLSM에서는 전기자 권선부의 슬롯-치 구조로 인한 디텐트력과 단부효과에 의한 디텐트력, 영구자석의 고조파 성분 자속에 의한 디텐트력이 발생한다. 따라서, 본 연구에서는 자기저항의 불연속으로 인한 디텐트력을 제거시키기 위하여 전기자 권선과는 독립된 자기회로를 가지는 보조코어의 설치를 제안하였다. 보조코어의 최적 설계는 유한요소 해석과 실험계획법을 이용하였으며 이론치와 실험치를 비교함으로서 본 연구의 타당성을 입증하였다.

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Compensation of the Discontinuous Properties of the Guide System using Magnetic Levitation (자기 부상 안내 기구의 불연속 특성 보상 방법)

  • Lee, Sang Joon;Jung, Kwang Suk
    • Journal of Institute of Convergence Technology
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    • v.3 no.2
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    • pp.11-15
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    • 2013
  • These days, the quality of goods is required to improve in the process of manufacturing the semiconductor through the short working hours and clean transportation. The non-contact transport device using magnetic levitation can be a solution in the manufacturing process. The non-contact transport device, using electromagnetic actuation, is the system that can actually transport them by only using attraction force from the electromagnetic source without authentic contact. Moreover, the system using electromagnetic force has a substantial number of benefits ranging from unrestricted design to unlimited expansion. Especially, the price is competitive. The non-contact transport device, using electromagnetic force, has another merits in controlling by giving the same amount of attraction force to ferromagnetic body. By controlling the currents given to coil, the operator is able to decide the direction of the transportation. In order to design the optimal system, we implemented five different things such as the presence of the links below the electromagnetic, the electromagnet changes due to coupling method, the change according to the thickness of the links below electromagnet, due to changes in between electromagnetic distance direction, and the size of the current. Through simulations and the optimum design, it seems to control easily and figure out the exact size of power. It might definitely be the non-contact transport that can sharply reduce tiny scratches and particles in the process of manufacturing the semiconductor.

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GaAs/A1GaAs HEMT구조의 2DEC 측정

  • Lee, Jae-Jin;Maeng, Seong-Jae;Park, Hyo-Hun;Kim, Jin-Seop;Ma, Dong-Seong
    • ETRI Journal
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    • v.11 no.4
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    • pp.67-74
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    • 1989
  • n-GaAs/A1GaAs계의 화합물 반도체 접합에 형성되는 이차원 전자 가스를 캐패시턴스-전압(C-V), 각도 의존 자기저항(SdH), 전자 빔 반사(EBER)등의 측정 방법을 통하여 A1GaAs 조성비(x)는 0.281, 전도대와 가전도대의 밴드 불연속은 각각 밴드 갭($E_g$)의 69%와 31%임을 알았고, 여기에 존재하는 이차원 전자가스의 면농도는 $5.4\times10^11cm^-2, 페르미 준위 $E_F$는 25mev임을 알았다. 또한 도핑 된 A1GaAs층에서 흔히 나타나는 Franz-Keldysh진동은 불순물의 활성화도가 작으면 형성되는 전기장의 약화로 나타나지 않는다는 것을 발견하였다.

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Kyeryong Mountain as a Contested Place (경합(競合) 장소(場所)로서의 계룡산(鷄龍山))

  • Ryu Je-Hun
    • Journal of the Korean Geographical Society
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    • v.40 no.5 s.110
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    • pp.553-570
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    • 2005
  • On Kyeryong Mountain, different religious(or ideological) groups have endowed space and place with amalgams of different meanings, uses and values. In addition to Buddhism and Confucianism, Shamanism and other popular beliefs have practiced their own ideologies(or powers) to create and maintain their own territories and identities. The geographies of resistance, involving Shamanism, have been scattered all over the mountain, discontinuous in the territorialization. These geographies of resistance could be identified the best around the most sacred sites, such as Sambulbong, Amyongch'u and Sutyongch'u. The entanglement of Shamanism with Buddhism, in various patterns through space and time, has indeed contributed to the survival of Shamanism as a subordinate power.

Review on the Three-Dimensional Magnetotelluric Modeling (MT 법의 3차원 모델링 개관)

  • Kim, Hee-Joon;Nam, Myung-Jin;Song, Yoon-Ho;Suh, Jung-Hee
    • Geophysics and Geophysical Exploration
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    • v.7 no.2
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    • pp.148-154
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    • 2004
  • This article reviews the development of three-dimensional (3-D) magnetotelluric (MT) modeling. The 3-D modeling of electromagnetic fields is essential in understanding the physics of MT soundings, and in implementing an inversion method to reconstruct a 3-D resistivity image. Although various numerical schemes have been developed over the last two decades, practical methods have been quite limited. However, the recent rapid improvement in computer speed and memory, as well as the advance in iterative solution algorithms for a large system of equations, makes it possible to model the MT responses of complex 3-D structures, which have been very difficult to simulate before. The use of staggered grids in finite difference method has become popular, conserving a magnetic flux and an electric current and allowing for realistic discontinuous fields. The convergence of numerical solutions has been greatly accelerated by adopting Krylov subspace methods, proper preconditioning techniques, and static divergence corrections. The vector finite-element method using edge elements is also free from the discontinuity problem, and seems a natural choice for modeling complex structures including irregular topography because its flexibility allows one to capture full geometric complexity.