• 한국세라믹학회지
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• 제39권3호
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• pp.321-326
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• 2002

착체중합법을 사용하여 nano-size의 ZnWO$_4$ powder를 제조하였다. 금속이온물질로서 znic nitrate와 tungstic acid를 사용하였으며 용매는 ethylene glycol을 사용하였다. 300$^{\circ}$C부터 600$^{\circ}$C의 온도 영역에서 하소한 분말에 대해 열분해 및 결정화 과정, 분말의 형상, 입도 변화 양상을 분석하였다. 일반적인 고상합성시에 필요한 온도보다 현저히 낮은 온도인 400$^{\circ}$C에서 ZnWO$_4$상이 생성되었으며, 600$^{\circ}$C에서 완전한 경정상을 얻을 수 있었다. 합성된 분말은 400$^{\circ}$C와 500$^{\circ}$C에서 원형과 silk-worm 형태가 혼합된 입자 형상을 나타내었고, 600$^{\circ}$C에서보다 균질한 양상을 나타내었다. 합성된 분말의 입자 크기는 400$^{\circ}$C∼600$^{\circ}$C의 온도영역에서 19.9∼24.2nm 정도로 매우 미세하였으며, 하소 온도가 증가함에 따라 분말의 결정상과 입도가 증가하는 것을 확인하였다.

• 한국결정학회지
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• 제11권1호
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• pp.42-45
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• 2000

The complex [Zn(L)Cl](H₂O)(ClO₄) (1) (L=3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,O/sup 1.18/,O/sup 7.12/]docosane) has been prepared and characterized by X-ray crystallography. 1 crystallizes in the monoclinic space group P2₁/c, with a=8.883(1), b=19.319(9), c=15.124(2)Å, β=101.65(1)°, V=2542.0(13) ų, Z=4, R₁(wR₂) for 4457 observed reflections of [I>2σ(I)] was 0.0640(0.1557). The coordination geometry around the zinc is a distorted square-pyramid with four nitrogen atoms of the macrocycle occupying the basal sites(Zn-N/sub av/=2.131(2)Å) and a chloride atom at the axial position with the Zn-Cl distance of 2.315(2)Å.

• 한국분말재료학회지
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• 제21권6호
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• pp.429-433
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• 2014

This study investigated the magnetic properties and frequency dispersion of complex permeability of Ni-Zn-Co ferrites used for magnetic shielding in near field communication (NFC) system. The sintered specimens of $(Ni_{0.7}Zn_{0.3})_{1-x}Co_xFe_2O_4$ composition were prepared by the conventional ceramic processing. The coercive force and saturation magnetization were measured by vibrating sample magnetometer. The complex permeability was measured by RF impedance analyzer in the range of 1 MHz~1.8 GHz. The coercive force increased and saturation magnetization decreased with increasing the Co substitution. The real and imaginary parts of complex permeability decreased and the resonance frequency increased with Co substitution, which was attributed to the increase in crystal anisotropy field and reduction in saturation magnetization. The effect of Co substitution could be found in reducing the magnetic loss to nearly zero at the operating frequency of NFC (13.56 MHz).

• 한국수소및신에너지학회논문집
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• 제16권3호
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• pp.262-268
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• 2005

[ $Zn(BH_4)_2$ ](8.4 wt% theoretical hydrogen storage capacity powders have been successfully synthesized by mechanochemical reaction from mixtures of $ZnCl_2$ and $NaBH_4$ powders in a 1:2 molar ratio in different times. $$ZnCl_2+2NaBH_4{\rightarrow}Zn(BH_4)_2+2NaCl$$ (1) $Zn(BH_4)_2$ powders were characterized by X-ray diffractometry(XRD), and Furier Transform Infrared spectrometry(FT-IR). The thermal stabilities of $Zn(BH_4)_2$ powders were studied by Differential scanning calorimetry(DSC), Thermogravimetry analysis(TGA), and Mass spectrometry(MS). $Zn(BH_4)_2$ can be tested for hydrogen evolution without further purification. The reaction to yield hydrogen is irreversible, the other products being compounds of Zn, and borane. $Zn(BH_4)_2$ thermally decomposes to release borane and hydrogen gas between about 85 and 150$^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.624-630
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• 2006

ZnO deposition parameters are not independent and have a nonlinear and complex property. To propose a method that could verify and predict the relations of process variables, neural network was used. At first, ZnO thin films were deposited by using RF magnetron sputtering process with various conditions. Si, GaAs, and Glass were used as substrates. The temperature, work pressure, and RF power of the substrate were $50\sim500^{\circ}C$, 15 mTorr, and $180\sim210W$, respectively : the purity of the target was ZnO 4 N. Structural properties of ZnO thin films were estimated by using XRD (0002) peak intensity. The structure of neural network was a form of 4-7-1 that have one hidden layer. In training a network, learning rate and momentum were selected as 0.2, 0.6 respectively. A backpropagation neural network were performed with XRD (0002) peak data. After training a network, the temperature of substrate was evaluated as the most important parameter by sensitivity analysis and response surface. As a result, neural network could capture nonlinear and complex relationships between process parameters and predict structural properties of ZnO thin films with a limited set of experiments.

• 한국자기학회지
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• 제6권6호
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• pp.382-387
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• 1996

본 연구에서는 ${(Ni_{x}Cu_{0.2}Zn_{0.8-x}O)}_{1-w}{(Fe_{2}O_{3})}_{1+w}$의 Ni 함량(x)과 $Co_{3}O_{4}$ 첨가량에 따른 복소투자율 변화에 관하여 검토하였다. Ni 함량 x=0.6 이상에서는 매우 좁은 투자율 허수항($\mu$") 피이크가 형성됨으로서 다른 조성에 비해 손실이 적음을 알 수 있었고 공명주파수($f_{\mu"max}$)는 Ni 함량의 변화와 비례하여 현저하게 증가하였다. $Fe_{2}O_{3}$ 결핍량(w)이 많을 수록 $\mu$" 값은 낮았으나, $Fe_{2}O_{3}$ 결핍량(w)의 변화가 공명주파수에는 큰 영향을 미치지 않는 경향을 나타내었다. NiCuZn 페라이트 조성에 대하여 $Co_{3}O_{4}$를 첨가한 경우는 첨가량이 많아짐에 따라 초기투자율이 감소하여 $f_{\mu"max}$ 값은 증가하였으나, 전체적인 손실의 정도를 제어하는데에는 Ni 함량을 변화시키는 것이 더 효과적임을 알 수 있었다.

• 대한화학회지
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• 제54권1호
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• pp.43-48
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• 2010

p-페닐렌 디아민과 maleic anhydride, 아세틸 아세톤과 커플된 O-아미노 페놀의 아조화합물으로 부터 폴리이미드가 만들어졌다. 합성된 폴리이미드(PA)는 DMF용매 속에 다른 몰비율로 녹아있는 $Co^{+2},\;Cr^{+2},\;Ni^{+2},\;Cu^{+2},\;Zn^{+2},\;Cd^{+2}$ and $Fe^{+3}$ 를 포함하는 전이금속이온들의 금속염들과 함께 환류되었다. 이 complex들은 원소분석과 열분석, IR, $^1H$ NMR으로 구조분석, 특성 연구되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.303-305
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• 1996

The electrical Properties of ZnO added TiO$_2$were investigated by using the complex impedance measurement and voltage-current source and measurement unit. The electrical conductivity of ZnO added TiO$_2$decrease with increasing the content of ZnO. The frequency-dependent Ac conductivity increase as frequency increase. Also, the trend of capacitances is similar to the AC conductivity. The semicircles of impedance spectrum increase with increasing ZnO contents. The decrease of electrical conductivity seems to be the effect of ZnO acceptor adding.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.103-106
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• 1997

The electrical properties and the sensing properties of ZnO-TiO$_2$ composites were investigated by using the complex impedance measurement and voltage-current source and measurement unit. In air, the electrical conductivity of TiO$_2$ added ZnO increase with increasing the content of TiO$_2$ and the relative dielectric constants for 3, 5 and 7mol% TiO$_2$ added ZnO are 7, 13 and 120, respectively. In 3000ppm CO gas, the relative dielectric constants for 3, 5mol% TiO$_2$ added ZnO are 25, 28, respectively.

• 한국농공학회논문집
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• 제48권1호
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• pp.3-10
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• 2006

The chemical fractions of heavy metals were investigated in the soils of reclaimed and natural tidelands of southwest coastal area of Korea. The distribution pattern of each heavy metal in different fractions was in the order: 1) Cu : organic bound > organic complex > residual > exchangeable = water soluble. 2) Cr : residual > organic bound > organic complex > water soluble > exchangeable. 3) Pb : organic bound > residual > organic complex > water soluble > exchangeable. 4) Cd residual > organic bound > organic complex > water soluble = exchangeable. 5) Zn : organic bound > residual > organic complex > water soluble > exchangeable. The content of residual Zn showed positive correlation with organic matter content but organic bound Zn showed negative correlation with CEC. The content of residual and exchangeable Cd showed highly positive correlation with organic matter content but residual, organic bound, and exchangeable Cd showed negative correlations with CEC. Water soluble Pb showed positive correlation with CEC but organic bound Pb showed negative correlation with CEC.