• Title/Summary/Keyword: 자기적성질

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자기연마를 이용한 미세 버제거 연구

  • ;;Yuri M.Baron
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.05a
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    • pp.259-259
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    • 2004
  • 정밀부품의 가공 시에 발생되는 burr는 제품의 정밀도, 성능과 제품의 생산성에도 부정적인 영향을 끼치다. 따라서 효율적인 burr의 제거는 제품의 성능의 향상뿐만 아니라 생산성의 향상에도 긍정적인 영향을 미칠 수 있다. 자기 연마법(Magnetic Abrasive Finishing)은 연마제의 연마특성과 철의 자기화 성질을 이용한다. 자기장내의 자기력선의 응집현상을 통해서 burr를 제거하는 방법이다. 자기 유도자에 의해 형성된 magnet flow를 따라 지립이 정렬을 하고 정렬된 지립은 브러쉬의 역할을 하여 burr를 제거하게 된다.(중략)

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The Multi-Frequency NMR Relaxation and EPR Study of Nano-sized Iron Oxide

  • 황문정;이영주;이일수;장용민
    • Proceedings of the KSMRM Conference
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    • 2002.11a
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    • pp.129-129
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    • 2002
  • 목적: 초상자성 nano 산화철 입자의 특성을 연구하기 위하여, 여러 다른 자기장 세기에서의 NMR 자기공이완시간(T1/T2)을 측정하고, 초상자성 nano-particle 조영제의 기전에 관한 모델로부터 얻어 진 계산식과 비교해보며, 다양한 온도에서의 EPR spectrum을 이용하여 이들의 전자적 성질을 비교해 보고자 하였다.

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Self-healing Engineering Materials: I. Organic Materials (자기치유 공학재료: I. 유기 재료)

  • Choi, Eun-Ji;Wang, Jing;Yoon, Ji-Hwan;Shim, Sang-Eun;Yun, Ju-Ho;Kim, Il
    • Clean Technology
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    • v.17 no.1
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    • pp.1-12
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    • 2011
  • Scientists and engineers have altered the properties of materials such as metals, alloys, polymers, ceramics, and so on, to suit the ever changing needs of our society. Man-made engineering materials generally demonstrate excellent mechanical properties, which often tar exceed those of natural materials. However, all such engineering materials lack the ability of self-healing, i.e. the ability to remove or neutralize microcracks without intentional human interaction. The damage management paradigm observed in nature can be reproduced successfully in man-made engineering materials, provided the intrinsic character of the various types of engineering materials is taken into account. Various self-healing ptotocols that can be applied for the organic materials such as polymers, ionomers and composites can be developed by utilizing suitable chemical reactions and physical intermolecular interactions.

Variation of the Magnetic Properties of Electrodeposited CoP Nanowire Arrays According to Their Size and Microstructure (CoP나노선재의 자기적 성질에 미치는 미세구조와 크기 효과)

  • Kim, Yi J.;Lee, Kwan H.;Jeung, Won Y.;Kim, Kwang B.
    • Journal of the Korean Electrochemical Society
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    • v.6 no.3
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    • pp.208-211
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    • 2003
  • We have investigated the dimensional and microstructural dependence of magnetic properties of CoP nano-wire arrays fabricated by electrodeposition on AAO(anodic aluminum oxide) templates with different-size nanopores. Our results indicate that the magnetic properties of nanowire arrays can be varied with their dimensions and microstructures. As for the CoP nanowire arrays with the diameter of 20nm, it was found to have the coercivity more than 2.6kOe due to the shape anisotropy and squareness(Mr/Ms) of $\~0.8$. The CoP nanowire arrays with the diameter of 200m, however, showed very different magnetic properties depending on the current densities. Nanowires fabricated at $5mA/cm^2$ had stronger tendency to have the preferred crystallographic orientation of (002) parallel to the nanowire than those fabricated at $35mA/cm^2$ These microstructural differences are the reason why CoP nanowire arrays prepared at different current densities exhibited different magnetic properties.

Nuclear Magnetic Resonance of Carbon Nanotube and Boron Nitride Nanotube (Carbon Nanotube 와 Boron Nitride Nanotube 의 핵자기공명)

  • 정재갑;유권상;남승훈;이규층;이무희;이영희
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.6
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    • pp.22-27
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    • 2004
  • 특성에 대한 많은 연구가 진행되었고, 새로운 나노 소자로서의 가능성을 보여왔다. CNT의 전기적 성질은 직경과 chirality 의 함수로서 금속 혹은 반도체 성질을 주기적으로 가지며, 이론적 연구에 의하면 단일구역의 CNT 는 1/3 이 금속성, 나머지는 밴드갭이 수 ㎷ 로 아주 작고, 나노튜브의 직경에 반비례하는 반도체 성질을 나타낸다.(중략)

Magnetic Properties of NdFeB Powders Prepared by Mechanical Alloying (기계적합금법으로 제조한 NdFeB계 분말의 자기적 성질)

  • Kim, Taek-Soo;Hwang, Yeon;Lee, Hyo-Sook
    • Journal of the Korean Magnetics Society
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    • v.8 no.4
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    • pp.210-215
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    • 1998
  • $Nd_{15}Fe_{77}B_8$ and $Nd_{16}Fe_{76}B_8$ powders were prepared by mechanical alloying in Ar atmosphere, and their phases and magnetic properties were investigated with as a function of the annealing temperature. It was found that the mechanical alloyed $Nd_{16}Fe_{76}B_8$ powder for 450 hours was amorphous phase with a part of $\alpha$-Fe crystallites. The obtained powders at 700 $^{\circ}C$ for 30 minute resulted in two phase of $Nd_2Fe_{14}B$ and $NdB_6$ by the solid-state reaction. The mechanical alloyed $Nd_{16}Fe_{76}B_8$ powder for 450 hour and annealed at 700 $^{\circ}C$ for 30 minute was showed $_iH_c\;of\;9.91\;kOe,\; B_{max}\;of\;12.93\;kG,\;Br\;of\;7.6\;kG\;and\;(BH)_{max}\;10.1\;MGOe$.

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