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강소영,이병태,이종운,문승현,김경웅 대한방사선 방어학회 2002 방사선방어학회지 Vol.27 No.1
가압경수로 일차냉각수내 탈염공정의 효과적 운용을 위하여 Amberlite IRN-77 양이온 교환수지의 특성 및 Co(II), Ni(II), Cr(III), Fe(III) 이온의 흡착거동을 연구하였다. 용존 금속이온 농도가 약 200 mgL^-1 인 용액 100 mL에 대하여 이온교환수지 투입량은 약 0.6g이 가장 적절하였으며, 이온교환 반응 속도 측정 결과 대부분의 흡착은 반응 1 시간 이내에 신속히 발생하였다. 수지에서의 양이온 교환은 Langmuir 흡착등온선을 잘 따르는 것으로 나타났으나, Fe(III)의 경우, 다른 금속과는 달리 쉽게 평형에 이르지 못하였으며 이는 공기와 오래 접촉한 결과 철산화물 또는 수산화물을 형성하며 용액 중으로부터 침전되기 때문인 것으로 관찰되었다. 전자가가 동일한 Co(II)와 Ni(II)가 동시에 포함된 모의 조제용액에 대하여 흡착실험을 한 결과, 각 이온은 거의 동일한 흡착 거동을 보였다. 그러나 전자가가 큰 Cr(III)이 첨가된 경우, 이들은 기존에 수지에 흡착되어 있던 전자가가 낮은 금속들을 탈착시키고 대신 흡착하는 경향을 보였다. 따라서 이온교환수지를 이용한 효과적인 탈염 공정을 위해서는 용존 금속 상호간의 경쟁적 흡착관계의 규명이 필요한 것으로 여겨진다. Characteristics of Amberlite IRN-77, a cation exchange resin, and the mechanisms of its adsorption equilibria with Co(II), Ni(II), Cr(III) and Fe(III) and Fe(III) ions were investigated for the application of the demineralizing process in the primary coolant system of a pressurized water reactor (PWR). The optimum dosage of the resin for removal of the dissolved metal ions at 200 mgL^-1 was 0.6 g for 100 mL solution. Most of each metal ion was absorbed onto the resin in an hour from the start of the reaction. Each metal adsorption onto the resin could be well represented by Langmuir isotherms. However, in the case of Fe(III) adsorption, continuous formation of Fe-oxide or -hydroxide and its subsequent precipitation inhibited the completion of the equilibrium between the metal and the adsorbent. Cobalt(II) and Ni(II), which have an equivalent electrovalence, were adsorbed to the resin with a similar adsorption amount when they coexisted in the solution. However, Cr(III) added to the solution competitively replaced Co(II) and Ni(II) which were already adsorbed onto the resin, resulting in desorption of these metals into the solution. The result was likely due to a higher adsorption affinity of Cr(III) than Co(II) and Ni(II). This implies that the interactively competitive adsorption of multi-cations onto the resin should be fully considered for an efficient operation of the demineralizing ion exchange process in the primary coolant system.
Domain wall motion driven by an oscillating magnetic field
Moon, Kyoung-Woong,Kim, Duck-Ho,Kim, Changsoo,Kim, Dae-Yun,Choe, Sug-Bong,Hwang, Chanyong IOP 2017 Journal of Physics. D, Applied Physics Vol.50 No.12
<P>The coherent unidirectional motion of magnetic domain walls (DWs) is a key technology used in memory and logic device applications, as demonstrated in magnetic strips by electric current flow as well as in films by oscillation of a tilted magnetic field. Here we introduce a coherent unidirectional motion of DWs in the strip, utilizing an oscillating field, which is described within a previous 1D model. The essential criterion for DW motion in this approach is the oscillating-field-induced modulation of the DW width, which has not been previously considered. This DW motion driven by width modulation sheds light on high frequency domain manipulation in spin devices. A comprehensive inspection of field angle dependence reveals that unidirectional DW motion in this model requires chiral DWs, followed by asymmetric deformation of the domain shape.</P>
Incoherent Domain Configuration Along Wire Width in Permalloy Nanowires
Kyoung-Woong Moon,Jae-Chul Lee,Myung-Hwa Jung,Kyung-Ho Shin,Sug-Bong Choe IEEE 2009 IEEE transactions on magnetics Vol.45 No.6
<P>Magnetization reversal in ferromagnetic Permalloy nanowires is experimentally investigated by measurement of the anisotropic magnetoresistance (AMR). Two distinct regimes of the magnetization reversal are observed with respect to the angle of the external magnetic field. For the regime of large angles, the AMR curves exhibit two distinct jumps, evidencing the existence of an intermediate transient state. The intermediate state is in the form of an incoherent magnetization configuration consisting of three domain structures with two Neel walls, due to the inhomogeneous shape anisotropy distribution, as confirmed by a micromagnetic prediction.</P>