• Title/Summary/Keyword: 자화 역전

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Magnetic Interaction and Magnetic Properties of Electrodeposited CoPt Magnetic Films with Different Thickness (전기도금법으로 제작한 CoPt 자성막의 자기상호작용과 자기적 성질)

  • Kim, Hyeon-Soo;Lee, Jong-Duck;Jeong, Soon-Young;Lee, Chang-Hyeong;Suh, Su-Jeong
    • Journal of the Korean Magnetics Society
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    • v.21 no.5
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    • pp.151-156
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    • 2011
  • The influence of thickness on magnetic interaction and magnetic properties in electrodeposited CoPt magnetic films was investigated from the analysis of the magnetic remanence curves and the magnetic hysteresis loops. As the thickness of the CoPt film is increased, the perpendicular coercivity and the saturation magnetization are increased but the squareness is considerably decreased. The analysis results of the magnetic remanence curves and the magnetic hysteresis loops exhibited that the dipolar interaction is the main interaction mechanism for all samples, but the strength of the dipolar interaction gradually increased with increasing sample thickness.

Anti-inflammatory and Anti-allergic Effects of Herbal Extracts on Atopic Dermatitis ( Part II ) (약용식물 추출물의 아토피성 피부염에 대한 항염증 및 항알레르기 효과 (제 2 보))

  • Rang, Moon-Jeong
    • Journal of the Korean Applied Science and Technology
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    • v.30 no.1
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    • pp.173-182
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    • 2013
  • Atopic dermatitis is a chronic, relapsing inflammatory skin disease associated with dysfunction of skin barrier and cutaneous hyper-reactivity to environmental triggers. In the previous study, cytotoxicity, antioxidant, anti-inflammatory and anti-allergic activities were investigated for various herbal extracts such as Aloe vera L. (AV), Viola mandshurica W. Becker (VM), Punica granatum L. (PG), and Dendrobium nobile L. (DN) in order to develop effective therapeutic herbal extracts for atopic dermatitis, In this study, anti-inflammatory activities of these herb extracts in lipopolysaccharide (LPS)-induced macrophage RAW264.7 cells were further examined to find the underlying molecular mechanisms. The RT-PCR (reverse transcription polymerase chain reaction) analysis showed that PG, DN and AV inhibited effectively the gene expression of pro-inflammatory cytokines IL-6 and IL-$1{\beta}$ in LPS-stimulated macrophages, while VM did not. The transfection and luciferase analysis exhibited that all herbal extracts hindered the activation of transcription nuclear factor kappa B (NF-${\kappa}B$). The western blot analysis indicated that AV blocked the activation of only JNK MAP (c-Jun N-terminal kinase mitogen-activated protein) kinase not p38 MAP kinase, while VM, PG and DN did not show the activation of both JNK and p38 MAP kinases. These results suggest that AV, VM, PG, and DN have anti-inflammatory activities and thus have the potential to reduce and alleviate the symptoms of atopic dermatitis.

Case studies for modeling magnetic anomalies with COMSOL Multiphysics® (콤솔 멀티피직스를 활용한 지자기장 모델링 사례 연구)

  • Ha, Goeun;Kim, Seung-Sep
    • Journal of the Geological Society of Korea
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    • v.54 no.6
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    • pp.677-682
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    • 2018
  • Magnetic anomalies are sensitive to magnetic properties present in deep Earth and near surface structures. Such geophysical characteristics often can be quantified by numerical analyses. In this study, we developed a finite element method (FEM) approach to compute magnetic anomalies using COMOL $Multiphysics^{(R)}$. This FEM approach was verified by comparing its numerical results with the previously known analytic solution for a uniformly magnetized sphere. Then, we used the method to compute magnetic reversal patterns near mid-ocean ridge with various faulting scenarios. This COMSOL-based approach can be incorporated into advanced multi-physical numerical models to understand the Earth.

Magnetoresistance Variation for Rotation in Ferromagnetic Thin Films (강자성체박막의 회전에 따른 자기저항의 변화)

  • Yang, Ki-Won;Park, Sang-Chul
    • Journal of Korean Ophthalmic Optics Society
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    • v.11 no.3
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    • pp.225-229
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    • 2006
  • In our angle configuration, several peculiar characteristic behaviors of MR could be observed, the mixing of positive MR(PMR) and negative MR(NMR) in the inclined sample was observed. The complete mixing angle, ${\phi}_{mix}$ as a function of inclination angle, ${\theta}$ was observed to fit well to the relation of ${\phi}_{mix}=tan^{-1}(1+tan{\theta})$ in nickel films. The above theoretical relation was obtained by decomposing the magnetic field into the components parallel and perpendicular to the current flow and identifying ${\phi}_{mix}$ as the angle satisfying that the above two components of magnetic field were identical. We also observed that the data of ${\phi}_{mix}$ did not satisfy the above theoretical relation in the iron film. This was explained by the fact that the growth direction in the iron film was an intermediate direction of magnetization, while the growth direction in the nickel film was an easy axis of magnetization.

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Magnetic Field Dependence of the Activation Volume for Sr-ferrite Particles (Sr-페라이트 자성 입자의 활성화 부피의 자기장 의존성)

  • Kim, Hyeon Soo;Jeong, Soon Young;Kim, Kyung Min;Kwon, Hae-Woong
    • Journal of the Korean Magnetics Society
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    • v.26 no.6
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    • pp.196-200
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    • 2016
  • In this study the mechanisms of magnetization reversal and magnetic interaction effects on activation volumes for Sr-ferrite with different particle sizes are investigated. The activation volumes of C2 sample are larger than those of C3 sample in the range of low magnetic fields. But the fields above the coercivity of sample C2, the activation volumes of both samples are decreased linearly with increasing the applied magnetic field. These phenomena can be explained by the strengths of two critical fields representing the reverse domain nucleation field and the domain wall pinning field as well as the strength of dipolar interaction.

Tunable Interlayer Exchange Coupling Energy (조절 가능한 층간교환상호작용에 관한 연구)

  • Ha, Seung-Seok;You, Chun-Yeol
    • Journal of the Korean Magnetics Society
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    • v.16 no.2
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    • pp.130-135
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    • 2006
  • We theoretically demonstrate that the interlayer exchange coupling (IEC) energy can be manipulated by means of an external bias voltage in a $F_1/NM/F_2/S$$(F_1:ferromagnetic,\;NM:nonmagnetic\;metallic,\;F_2:ferromagnetic,\;S:semiconductor\;layers)$ four-layer system. It is well known that the IEC energy between two ferromagnetic layers separated by nanometer thick nonmagnetic layer depends on the spin-dependence of reflectivity to the $F_1/NM/F_2/S$ four-layer system, where the reflectivities at the interface in $NM/F_2$ interface also depends on $F_2/S$ interface due to the multiple reflection of an electron-like optics. Finally, the IEC energy depends on the spin-dependent electron reflectivity not only at the interfaces of $F_1/NM/F_2$, but also at the interface of $F_2/S$. Naturally the Schottky barrier is formed at the interface between metallic ferromagnetic layer and semiconductor, the Schottky barrier height and thickness can be tailored by an external bias voltage, which causes the change of the spin-dependent reflectivity at $F_2/S$ interface. We show that the IEC energy between two ferromagnetic layers can be controlled by an external bias voltage due ti the electron-optics nature using a simple free-electron-like one-dimensional model.