• Title/Summary/Keyword: 자기성장

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Effects of an External Magnetic Field During Electrodeposition on the Magnetic Properties of CoPtP Alloys (전기도금 시 외부자기장이 CoPtP 합금의 자기 특성에 미치는 영향)

  • Jeung, W.Y.;Park, H.D.
    • Journal of the Korean Magnetics Society
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    • v.15 no.5
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    • pp.276-281
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    • 2005
  • We have investigated the effects of an external magnetic field on the growth direction and the grain size of electrochemically prepared CoPtP alloys. Electrodeposited CoPtP alloys were synthesized by appling an external magnetic field with 0 to 1 T to the perpendicular direction of the films. In the electrodeposited CoPtP alloys without external magnetic field, the growth direction of the alloys was mixed by fcc (111) and hop (002), but only hop (002) was observed in the alloys with 1 T external magnetic field. CoPtP alloys were grown as the columnar growth and the grain size increases with growing the alloys. With appling an external field, the grain size of the alloys was controlled less than 20 nm which is smaller than single domain of Co, and the easy axis of alloys, hcp (002) direction, was grown perpendicular to the films up to 200 nm. We could obtain the optimal thickness of the alloys and electrodeposition condition from the above results. Coercivity and squareness of CoPtP alloys taken out-of-plane are 6.1 kOe and 0.9, respectively. The magnetic properties of CoPtP alloys were measured by VSM, and the microstructural characterization and crystalline orientation measurement of the alloys were carried out by TEM and XRD.

Growth and Characterization of Epitaxial YIG Films for Microwave Devices (마이크로파 소자용 에피틱시 YIG막의 성장과 특성)

  • 김덕실;조재경
    • Journal of the Korean Magnetics Society
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    • v.9 no.2
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    • pp.91-97
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    • 1999
  • YIG $(Y_3Fe_5O_{12})$ films with 4~80 ${\mu}{\textrm}{m}$ thickness were epitaxially grown on GGG $(Gd_3Ga_5O_{12})$ substrates by LPE (liquid phase epitaxy) techniques. Using various melts having different chemical composition the growth temperature was varied as a parameter. Growth rate, surface morphology, chemical composition, lattice constant, saturation magnetization, and magnetic resonance of the films were investigated. Lattice mismatch between the substrate and film Δa, saturation magnetization, and magnetic resonance line width ΔH increased, decreased, and increased, respectively, as undercooling temperature ΔT increased. The films grown by using the melt with larger R$_1$and smaller R$_3$had smaller ΔH. The major origin of the increase of ΔH was the increase of Δa. It is considered that the magnetic field in the film became locally inhomogeneous with the increase of Δa due to the increase of inhomogenity in stress distribution to the film depth direction. Therefore, in order to grow YIG films with small microwave loss it is necessary to grow films at small ΔT using the melt with large R$_1$and small R$_3$resulting in a small Δa.

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Effect of asymmetric magnetic fields on the interface shape in Czochralski silicon crystals (Cz 실리콘 단결정에서 비대칭 자기장이 고액 계면에 미치는 영향)

  • Hong, Young-Ho;Shim, Kwang-Bo
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.4
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    • pp.140-145
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    • 2008
  • Silicon single crystals are grown by Czochralski (CZ) method in different growing conditions. The different shapes of the crystal-melt interface are obtained with various magnetic fields. Effects of zero-Gauss plane (ZGP) shape and magnetic intensity (MI) on the crystal-melt interface in the crystal experimentally are investigated. The shape of ZGP is not only flat but also parabolic, which is due to magnetic ratio (MR) of the lower to upper current densities in the configurations of the cusp-magnetic fields. As the MR increases, the crystal-melt interface becomes more concave. It means that the hot melt can be easily transported to the crystal-melt interface with increasing the MR. Effective shape of the crystal-melt interface is found to depend on the magnetic field in cusp-magnetic CZ method. The experimental results are compared with other studies and discussed.

CoFe2O4 Films Grown on (100) MgO Substrates by a rf Magnetron Sputtering Method ((100) MgO 기판에 성장한 CoFe2O4 박막의 물리적 및 자기적 특성에 관한 연구)

  • Lee, Jae-Gwang;Chae, Kwang-Pyo;Lee, Young-Bae
    • Journal of the Korean Magnetics Society
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    • v.16 no.2
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    • pp.140-143
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    • 2006
  • Single crystalline $CoFe_2O_4$ thin films on (100) MgO substrates were fabricated using a rf magnetron sputtering method. The deposited films were investigated for their crystallization by X-ray diffraction, Rutherford back-scattering spectroscopy and field emission scanning electron microscopy. When a cobalt ferrite film was deposited at the substrate temperature of $600^{\circ}C$, squared grains of about 200 nm were uniformly distributed in the film. However, the grains became irregular and their sizes also varied from 30 to 150 nm when the substrate temperature was $700^{\circ}C$. Hysteresis loops of a film deposited at $600^{\circ}C$ showed that the magnetically easy axis of the film was perpendicular to the substrate surface. Except for the squareness ratio, magnetic properties of the cobalt ferrite films grown by the present rf sputtering method were as good as those of the films prepared by a laser ablation method: The in-plane and perpendicular coercivities were 283 and 6800 Oe, respectively. As the thickness of the deposited film increased twice, the saturation magnetization became double but the coercivity remained unchanged. However, deposition of the Co ferrite films with a higher rf powder decreased the squareness ratio and the perpendicular coercivity of the films.

A Study on the Variables Affecting Self-Directed Learning of Workers: Focusing on Hope and Growth Mindset (직장인들의 자기주도적 학습에 영향을 미치는 변인: 희망과 성장 마인드셋을 중심으로)

  • Lee, Chang-Seek;Ryu, Eun-Kyung;Jang, Ha-Young
    • Journal of Digital Convergence
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    • v.16 no.9
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    • pp.29-37
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    • 2018
  • The purpose of this study was to investigate factors affecting self-directed learning of workers. For this purpose, 335 workers were surveyed in two cities in the northwestern part of Chungcheongnamdo. The research was carried out by difference test to identify the diffrence of self-directed learning according to general characteristics and by correlation analysis of main variables. Also in order to identify the effect of hope and growth mindset on self-directed learning, hierarchical regression analysis was conducted by diving the group into employee-level and higher employee-level. The main results are as follows. First, Self-directed learning differed by gender. Second, correlation analysis revealed that hope, growth mindset and self-directed learning were positively correlated. Third, regression analysis showed that the pathway thinking of hope and the intelligence of the growth mindset influenced self-directed learning of employee-level workers. And it showed that the pathway thinking of hope influenced self-directed learning of higher employee-level workers. Finally, we discussed policies to enhance workers' self-directed learning based on positions.

Korean Music Therapy Students' Growth in Supervision: A Modified Grounded Theory (음악치료 전공생이 수퍼비전에서 경험하는 성장에 대한 연구)

  • Yun, Juri
    • Journal of Music and Human Behavior
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    • v.10 no.2
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    • pp.35-54
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    • 2013
  • The purpose of this study was to examine how Korean music therapy students experience growth under clinical supervision. The investigator conducted in-depth qualitative interviews with 9 students from 3 different universities in Seoul who had at least three semesters of clinical supervision. Data was analyzed using a modified grounded theory approach to construct the growth experience of music therapy supervisees. Results suggest that growth can be understood in terms of both personal and professional domains and includes four types of experiences: growth hindering, fostering, mediating, and revealing. In the personal domain, hindering factors are defensiveness, narcissistic trauma, avoidance and anxiety whereas growth fostering and mediating factors include reflection on self, musical self, unconscious drives and conflicting issues as well as self-driven problem solving skills. As a result, growth in the personal domain is associated with increased self-acceptance and self-awareness. Growth in the professional domain is hindered by having trust issues, performance anxiety, identity crisis, and being hypersensitive to the judgment of others. On the other hand, growth is fostered and mediated by opening the self and interacting more with others, building trusting relationships with peers and supervisors, and establishing a new relationship with music, which leads to improved attitude, increased motivation, and more efficient and effective training.