• 제목/요약/키워드: magnetic separation

검색결과 407건 처리시간 0.034초

경사 자기장 하에서의 조셉슨 볼텍스 동역학 (Josephson Vortex Dynamics in Tilted Magnetic Fields)

  • 진용덕;기동근;이후종
    • Progress in Superconductivity
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    • 제9권2호
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    • pp.140-145
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    • 2008
  • We report on the Josephson vortex dynamics in $Bi_2Sr_2CaCuO_{8+\delta}$ natural Josephson junctions by c-axis tunneling measurements. Beside the quasiparticle branches in the current-voltage characteristics, a new set of multiple branches, referred to as Josephson-vortex-flow branches (JVFBs), are observed. The JVFBs emerge in an in-plane magnetic field above $H_0\;=\;{\Phi}_0/{\gamma}s^2$ and show highly hysteretic behavior, which can be explained in terms of the recently proposed dynamic-phase-separation model. In this work we examined the effect on the JVFBs by the presence of pancake vortices generated as the external magnetic field was applied slightly tilted from the in-plane direction. JVFBs were found to become larger and prominent with increasing pancake vortex density as the tilt angle increased, which were presumably caused by slowing down of a Josephson vortex lattice in the presence of pancake vortices.

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탠덤형 자석 소호기를 사용한 760V급 직류 개폐기의 차단 특성 (760 V-Class DC Switch Breaking Characteristics Using Tandem Type Magnet Extinguisher)

  • 김효성
    • 전력전자학회논문지
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    • 제27권3호
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    • pp.175-179
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    • 2022
  • Magnetic arc extinguishing technology is effective as an extinguishing device for low-voltage direct current (DC) circuit breakers with a resistive load of ≤4 kW. The separation distance between the magnet and the electrical contact must be shortened to increase the magnetic arc extinguishing force. However, if the magnet is installed too close to the electrical contact points, the magnet is exposed to high temperatures due to the arc current generated when the load current is cut off and the magnetism is lost. To solve this problem, the effective magnetic flux density at the electrical contact can be maintained high by placing the arc extinguishing magnet in a tandem structure with the electrical contact point between them, and the proper separation distance between the contact points and the magnet can be maintained. In addition, an electric arc extinguishing technology that emits arc energy using a series circuit of diode and resistor is used to suppress the continuous arc voltage generated by the inductive load. For the proposed circuit breaker, the breaking characteristics are analyzed through the breaking test for the DC load of the 760 V level, the load power of 4 kW, and the time constant of 5 ms, and an appropriate arc extinguishing design guideline is proposed.

Synthesis of Nanomaterials such as fluorescent-magnetic Nanoclusters and Frequency Doubling Nanowires for Bioapplications

  • Jeong, Jinhoo;Kim, Seungwook;Kim, Woong
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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    • pp.132.1-132.1
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    • 2014
  • Fluorescent-magnetic nanoclusters were synthesized for biomedical applications. The nanoclusters consisted of superparamagnetic core-nanoclusters, highly fluorescent shell of nanocrystals, and lipid A. Magnetic cores were used for both magnetic resonance imaging (MRI) and cell separation. Fluorescent shell was used for optical imaging. The lipid-A-loaded nanoclusters were up-taken by dendritic cells via phagocytosis, which successfully activated dendritic cells. The dendritic cells were migrated to lymph nodes and spleen of mice. The results showed that our novel nanoclusters can play a role as an efficient optical and magnetic imaging, a cell separating and a pathogen mimetic agent at the same time. Additionally, synthesis of wavelength conversion nanowires will be discussed, which may be used as an optical nanoprobe in biological studies.

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Co-22%Cr 자성합금박막에서 박막두계에 따른 자기미세구조 변화 (The change of magnetic microstructure with Co-22%Cr film thicknesses)

  • 송오성
    • 한국표면공학회지
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    • 제31권5호
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    • pp.261-265
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    • 1998
  • We investigated compositional separation of Co-23%Cr magnetic alloy thin films with varying film thicknesses. Saturation magnetization and magnetic microstructures were investigated using vibrating sample magnetometer (VSM) and scanning probe microscope (SPM), respectively. Saturation magnetization was as 700 emu/cc for films below 50 nm-thick, and changed to 430 emu/cc for the ones above 2000 nm-thick. This may be due to increment of molar volume of Cr-enriched phase as film thickness increases. The surface grain size in AFM (atomic force microscope) measurement becomes larger as film thickness increases. The MFM (magnetic force microscope) reveals that magnetic microstructure is changed from the fine spherical domains to the maze type domains as film thickness increases. We conclude that employing thickness of Co-22%Cr films below 50 nm is favorable for high density recording in order to enhance perpendicular saturation magnetization and SNR (signal to noise ratio).

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기계적 처리에 의한 반도체 IC칩 스크랩으로부터 유가금속의 분리에 관한 연구 (Separation of Metals from Intergrated Circuit Chip Scrap by Mechanical Beneficiation)

  • 이재천;이강인;이철경;양동효
    • 자원리싸이클링
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    • 제3권1호
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    • pp.38-43
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    • 1994
  • 국내의 반도체 회사에서 발생한 IC칩 스크랩의 기계적인 전처리를 통하여 귀금속 및 유가금속을 분리하는 연구를 행하였다. IC칩 스크랩을 절단, 분쇄한 뒤 분쇄된 스크랩의 입자크기에 따른 금속의 분포도를 조사하였으며 함유되어 있는 금속편을 자력선별에 의하여 분리하였다. 일련의 분쇄공정을 통하여 얻어 진 IC칩 스크랩 분쇄물의 입도분포는 +3 mm가 7.5%, 3~1 mm가 17.0%, -1 mm가 75.5%야였다. 분쇄물을 $700^{\circ}C$에서 배소하였을 때 중량감소율은 약 18%이였으며 입도분포에 따른 금속의 함량은 十3mm에서 97%, 1~3mm에서 96%, 1~0.595 mm에서 13% 및 0.595~0.5mm에서 3.7%이었다. Au는 99%가 -lmm의 분쇄물에 존재하였다. 자력선별기를 사용하여 700 및 1,500 Gauss로 Ni, Fe, Cu, Sn, Pb를 분리 회수할 수 있었다.

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