• 천문학회보
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• 제44권2호
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• pp.55.2-55.2
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• 2019

The firehose instability is driven by a pressure anisotropy in a magnetized plasma when the temperature along the magnetic field is higher than the perpendicular temperature. Such condition occurs commonly in astrophysical and space environments, for instance, when there are beams aligned with the background magnetic field. Recently, it was argued that, in weak quasi-perpendicular shocks in the high-β intracluster medium (ICM), shock-reflected electrons propagating upstream cause the temperature anisotropy. This electron temperature anisotropy can trigger the electron firehose instability (EFI), which excites oblique waves in the shock foot. Scattering of electrons by these waves enables multiple cycles of shock drift acceleration (SDA) in the preshock region, leading to the electron injection to diffusive shock acceleration (DSA). In the study, the kinetic properties of the EFI are examined by the linear stability analysis based on the kinetic Vlasov-Maxwell theory and then further investigated by 2D Particle-in-Cell (PIC) simulations, especially focusing on those in high-β (β~100) plasmas. We then discuss the basic properties of the firehose instability, and the implication of our work on electron acceleration in ICM shock.

• 한국자기학회지
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• 제10권6호
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• pp.280-294
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• 2000

RF-DC 마그네트론 스퍼터링을 이용하여 5$\times$$10^{-3}$ Torr의 알곤 가스 분위기에서 [(300nm)Ta/(500nm)NdFeB/(300nm)Ta] 영구자석 박막을 제조한 후 이의 미세구조 및 자기특성을 조사하였다 650-75$0^{\circ}C$로 가열된 Si 기판위에 성막한 [Ta/ NdFeB/Ta] 박막은 수직자기이방성과 함께 우수한 경자기특성을 나타내었으며, 특히 기판온도 $650^{\circ}C$와 $700^{\circ}C$에서 제조된 박막은 막면에 수직한 방향으로 각각 20 MGOe의 최대자기에너지적과 18.9 kOe의 큰 고유보자력을 나타내었다.

• 한국자기학회지
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• 제16권3호
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• pp.173-177
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• 2006

수직자기이방성을 갖는 [Pd/Co] 다층박막으로 구성된 스핀밸브 구조에서 비자성층(space layer, SL) Pd 또는 Cu의 두께와 다층박막의 반복층수 N에 따른 자기저항효과의 의존성을 연구하였다. 비자성층을 Pd보다 Cu로 사용하였을 때 더 큰 자기저항비를 얻었다. 그리고 Cu층과 고정층 사이에 Co층을 삽입하는 경우 약 3배가량 자기저항비가 증가하는 것을 관찰하였다. $Ta_{(2.1nm)}/[Pd_{(0.61)}/Co_{(0.23)}]_4/Cu_{(2.37)}/Co_{(t)}/[Pd_{(0.61)}/Co_{(0.23)}]_2/FeMn_{(10.6)}/Ta_{(2.1)}$ 구조에서 삽입된 Co층의 두께가 0.62nm 또는 1.01nm에서 최대의 자기저항비 7.4%를 얻었다.

• 한국세라믹학회지
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• 제37권4호
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• pp.320-326
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• 2000

Development of texture in SiC materials by hot-pressing and subsequent annealing was studied. Crystallographic texture type was characterized by measuring X-ray pole figures on the perpendicular plane to the hot-pressing direction. Observed all pole figures were nearly axially symmetric (fiber texture). In case of ${\beta}$-SiC materials, the pole density of basal plane (0004) increased as annealing time increased, in contrast, other planes (hkil) of ${\beta}$-SiC materials and all planes of ${\alpha}$-SiC materials nearly remained unchanged. In the case of ${\beta}$-SiC materials, therefore, a weak texture of (0001) plane at the normal direction took place in the 8h annealed samples, resulting from grian growth. The fracture toughness values of ${\alpha}$-SiC materials measured in both planes parallel and perpendicular to the hot-pressing direction were very similar. However, the fracture toughness of ${\beta}$-SiC materials measured parallel to the hot-pressing direction were higher than that measured perpendicular to the hot-pressing derection, relatively, because of the texture and the microstructure anisotropy.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 somma/kms meeting
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• pp.61-61
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• 2003

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.182.2-182.2
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• 2007

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2009년도 임시총회 및 하계학술연구발표회
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• pp.145-145
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• 2009

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2009년도 정기총회 및 동계학술연구발표회
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• pp.82-83
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• 2009

• 한국진공학회:학술대회논문집
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• 한국진공학회 2003년도 제25회 학술발표회 초록집
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• pp.140-140
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• 2003

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2013년도 임시총회 및 하계학술연구발표회
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• pp.76-77
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• 2013