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자전 연소 전구체로 합성한 나노 크기 경/연 복합페라이트의 자기 특성
오영우,안종견,Oh, Young Woo,Ahn, Jong Gyeon 한국마이크로전자및패키징학회 2015 마이크로전자 및 패키징학회지 Vol.22 No.3
Glycine-nitrate와 citric acid를 이용하여 단상의 Ni-Zn ferrite, Ba-ferrite 나노입자와 두 나노복합체 ferrite의 전구체를 제조하고 이를 열처리하여 XRD 및 FT-IR로 각각의 상 분석을, SEM으로 분말의 형상과 크기를, VSM으로 자기적 특성과 합성된 나노복합체 ferrite에서의 exchange-coupling 상호작용을 확인하였다. XRD 분석 결과, 자전 연소법으로 얻은 전구체로 단상의 Ni-Zn ferrite와 Ba-ferrite 나노 입자 및 $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ 나노복합체 페라이트가 합성되었으며, 나노복합체에는 $BaFe_{12}O_{19}$와 $Ni_{0.5}Zn_{0.5}Fe_2O_4$가 잘 분포되어 있어 경자성과 연자성이 공존하고 있음을 확인하였고, 나노복합체 페라이트의 히스테리시스 곡선의 형상을 통해 경자성과 연자성 사이에 exchange-copuling이 잘 이루어졌음을 확인할 수 있었다. VSM으로 측정한 나노복합체의 경우. GNP로 제조한 precursor를 $900^{\circ}C$에서 하소한 $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ 나노복합체는 포화자화 81.69 emu/g, 잔류자화 38 emu/g, 보자력 2598.48G를 나타내었다. $Ni_{0.5}Zn_{0.5}Fe_2O_4/BaFe_{12}O_{19}$ 복합체에서 $BaFe_{12}O_{19}$의 무게비가 증가 할수록 보자력은 증가하였고, 포화자화값과 잔류자화 값은 감소하였다. The goal of this research is the create novel magnets with no rare-earth contents, with larger energy product by comparison with currently used ferrites. For this purpose we developed nano-sized hard-type/soft-type composite ferrite in which high remanent magnetization (Mr) and high coercivity (Hc). Nano-sized Ba-ferrite, Ni-Zn ferrite and $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ composite ferrites were prepared by sol-gel combustion method by use of glicine-nitrate and citric acid. Nanocomposite ferrites were calcined at temperature range $700-900^{\circ}C$ for 1h. According to the X-ray diffraction patterns and FT-IR spectra, single phase of NiZn-ferrite and Ba-ferrite were detected and hard/soft nanocomposite ferrite was indicated to the coexistence of the magnetoplumbite-structural $BaFe_{12}O_{19}$ and spinel-structural $Ni_{0.5}Zn_{0.5}Fe_2O_4$ that agreed with the standard JCPDS 10-0325 data. The particle size of nanocomposite turn out to be less than 120 nm. The nanocomposite ferrite shows a single-phase magnetization behavior, implying that the hard magnetic phase and soft magnetic phase were well exchange-coupled. The specific saturation magnetization ($M_s$) of the nanocomposite ferrite is located between hard ($BaFe_{12}O_{19}$) and soft ferrite($Ni_{0.5}Zn_{0.5}Fe_2O_4$). The remanence (Mr) of nanocomposite ferrite is much higher than that of the individual $BaFe_{12}O_{19}$ and $Ni_{0.5}Zn_{0.5}Fe_2O_4$ ferrite, and $(BH)_{max}$ is increased slightly.
열분해법과 혼합가스 질화법으로 합성한 FePtN 나노 입자의 특성
오영우(Young Woo Oh) 한국자기학회 2016 韓國磁氣學會誌 Vol.26 No.4
The effect of thermal-nitrification on L1o transfomation in nano-sized FePt particles was studied. As-synthesized FePt nanoparticles by thermal decomposition method have fcc structured phase and their Hc and Ms were 247.34 Oe and 27.308 emu/g, respectively. According to the XRD analysis, phase transformation from fcc (face centered cubic) to fct (face centered tetragonal) structure was revealed by heating under NH<SUB>3</SUB>+H<SUB>2</SUB> mixed-gas atmosphere. Also a slight shift of each (111) peak indicated phase transformation from fcc to fct structure. Hc and Ms of fct FePtN were 1058.2 Oe and 32.718 emu/g, respectively. The nano-sized FePtN magnetic particles synthesized by thermal decomposition method and mixed-gas nitrification are expected for advanced applications such as high density magnetic recording media and biomedical materials.
Fe₄N 나노분말과 Fe₁₇Sm₂N<SUB>x</SUB> 자성분말의 자기적 특성
오영우(Young Woo Oh),이정구(Jung Goo Lee),박상준(Sang Jun Park) 한국자기학회 2012 韓國磁氣學會誌 Vol.22 No.3
Nano-magnetic materials such as iron-nitrides have been actively studied as an alternative to the application of high density, high performance needs for next generation information storage and also alternative to the rare earth and neodymium magnet. Fe₄N is the basic materials for magnetic storage media and is one of the important magnetic materials in focus because of its higher magnetic recording density and chemical stability. Single phase γ’-Fe₄N nanoparticles have been prepared by a PAD (Plasma Arc Discharge) method and nitriding in a NH₃-H₂ mixed gases at temperature, 400 ℃ for 4 hrs. Also Fe₁?Sm₂N<SUB>x</SUB> powders were synthesized by nitriding after reduction/diffusion of Fe₁?Sm₂ to compare the magnetic properties with nano-sized Fe₄N particles. The saturation magnetization of Fe₄N and Fe₁?Sm₂N<SUB>x</SUB> were 149 and 117 emu/g, respectively, but the coercive force was considerably smaller than that of bulk or acicular Fe₄N.
오영우(Oh Young Woo),임종인(Lim Jong In) 한국정보법학회 2010 정보법학 Vol.14 No.2
온라인을 통한 저작권침해의 대부분은 포털, P2P, 웹하드, UCC 등 서비스를 제공하는 온라인서비스제공자(Online Service Provider, OSP)의 인터넷 사이트를 통해서 이루어진다. 그 동안은 인터넷의 특성으로 인해 온라인상 불법 저작물을 복제 전송하여 유통시킨 직접 침해자인 개인을 특정하기가 쉽지 않을 뿐만 아니라 특정이 가능하더라도 손해배상 능력이 없는 경우가 많아 OSP에게 책임 추궁이 집중되었다. 하지만 OSP의 책임을 너무 지나치게 인정하고 규제를 강화할 경우 오늘날 지식 및 정보의 유통에 핵심적 역할을 하는 OSP의 사업이 심각하게 위축될 수 있다는 비판이 제기되고 있으며, 이에 따라 저작권보호와 정보 및 지식의 자유로운 유통을 합리적으로 조율할 수 있도록 하는 효율적인 규제방안 마련이 중요한 상황이다. 이에 따라 이 글에서는 온라인상 저작권보호를 위해 OSP를 중심으로 한 이해당사자들 사이의 상생을 위한 협력과 자율규제의 필요성을 살펴보고, 이어서 우리나라의 자율규제 현황분석을 토대로 우리 현실에 맞는 바람직한 자율규제 활성화 방안으로 OSP 의 자율규제 분위기 조성을 위한 입법적 정비, OSP의 자율규제 기구 참여 확대, 필터링 관련 OSP와 저작권자의 적극적인 협력 모색, OSP의 불법저작물에 대한 공동 대응방안 마련 등 4가지를 제시하였다. The majority of online copyright infringement occurs on internet sites hosted by Online Service Providers(the “OSPs”). Up until now, the OSPs have been targeted in terms of legal liability due to a difficulty in identifying the individuals who committed direct infringement activities and financial inabilities of such direct infringers. However, there has been criticism that shifting much of the liability to the OSPs provisioned by the tightened regulation is likely to result in the chilling effect of the OSPs’ activities that have played critical roles in the proliferation of free distribution of information. Thus, it appears that we have reached a turning point that calls out for an efficient regulatory mechanism that promotes the free distribution of information, but yet still promotes the protection of copyright at the same time. This paper looks into a way to promote the collaboration and cooperation among the interested parties, especially, by the OSPs, for the protection of copyright in online world. This paper further proposes based on the current status of self-regulatory framework a promotion of self-regulation that addresses the specific concerns we face in Korea. The four proposals include (1) a modification of legislative framework that creates the mood for active participation by the OSPs in the self-regulatory framework (2) a promotion of participation of OSPs in self-regulatory bodies, (3) an active collaboration in filtering of infringing materials by and among the OSPs and the copyright owners, and (4) a preparation of a counterplan to be adopted by the OSPs to respond to the distribution of copyright-infringing contents.