• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.49-53
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• 2022

In this study, quantum dot light-emitting diodes (QLEDs) of the optimized EL performance with a radio frequency (RF) sputtered Zn_0.85Mg_0.15O thin film as an electron transport layer (ETL). In typical QLEDs, ZnO nanoparticles (NPs) are widely used materials for ETL layer due to their advantages of high electron mobility, suitable energy level and easy capable of solution processing. However, the instability problem of solution-type ZnO NPs has not yet been resolved. To solve this problem, ZnMgO thin film doped with 15% Mg of ZnO was fabricated by RF sputtering and optimized for the device applied as an ETL. The QLEDs of optimized ZnMgO thin film exhibited a maximum luminance of 15,972 cd/m² and a current efficiency of 7.9 cd/A. Efficient QLEDs using sputtering ZnMgO thin film show the promising results for the future display technology.

• Journal of Environmental Health Sciences
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• v.10 no.2
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• pp.79-87
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• 1984

The purpose of the study is to determine the effects of Zn in lead poisoning rats by way of examining interaction mechanism of Pb and Zn. The fifty-five rats were Pb divided into four groups such as Zn group, group, Pb and Zn group, and control group. The rats of Zn group and of Zn and Pb group were subdivided into four groups by dose of Zn respectively 250mg/l, 500mg/l, 1, 000mg/l and 2, 000 mg/l. The rats having been fed the above mentioned chemicals, were weighed every five days for fifty-five days, and the subjects were slaughtered for measuring $\delta$-ALAD activities in blood and the accumulation amount of the chemicals in livers and kidneys. The results of the study are summarized as following 1. As for body weight gains, those of the control group rats were the highest, and those of Pb group the lowest. 2. $\delta$-ALAD activities of Pb group showed the tendency of decrease in comparison with those of control group. In Zn group, the subgroups of 250mg/l and 500mg/l showed higher activities than control group, whereas the subgroups of 1, 000mg/l and 2.000mg/l showed lower. 3. Hb value of Pb group was lower than that of control group. In Zn group, Hb value of the groups of 250mg/l and 500mg/l was a little higher than that of control group, while that of the groups of 1, 000mg/l and 2, 000mg/l was lower. 4. The amount of Pb and Zn accumulated in liver was much higher than in kidney. The amount of Pb accumulated in organs of Zn and Pb group decreased gradually in contrast to high concentration of Zn.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.11-11
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• 2006

ZnO는 넓은 밴드갭(3.37eV)과 큰 액시톤(exciton) 결합에너지(60meV)를 가지는 II-VI족 화합물 반도체이다[1]. 이와같은 특성은 상온에서도 높은 재결합 효율이 기대되는 엑시톤 전이가 가능하여 자발적인 발광특성 및 레이저 발진을 위한 낮은 임계전압을 가져 일광효율이 큰 장점이 있다. 최근에는 ZnO의 전기적, 광학적, 자기적 특성을 높이기 위해 doping에 대한 연구가 많이 보고 되고 있다. 이중 ZnO내에 Mg을 doping하게 되면 Mg 조성에 따라 밴드갭이 3.3~7.7eV까지 변하게 된다. 그러나 이원계 상평형도에 따라 ZnO내에 고용될 수 있는 MgO의 고용도는 4at% 이하이다. 이는 ZnO는 Wurtzite 구조이고, MgO는 rocksalt 구조로 각각 결정구조가 다르기 때문이다. 본 연구는 열기상증착방법(thermal evaporation)으로 ZnO 템플레이트를 이용하여 MgZnO 나노막대를 합성하였고, Zn와 Mg의 서로 다른 녹는점을 이용해 2-step으로 성장을 하였다. 합성은 수평로를 사용하였으며, 반응온도 550, $700^{\circ}C$로 2-step으로 하였으며, 소스로 사용된 Zn(99.99%)과 Mg(99.99%) 분말을 산소를 직접 반응시켜 합성하였다. Ar 가스와 O2 가스를 각각 운반가스와 반응가스로 사용하였다. ZnO 템플레이트 위에 성장시킨 1차원 MgZnO 나노구조의 형태 및 구조적 특성을 FESEM과 TEM으로 분석하였다. 그리고 결정학적 특성은 XRD를 이용해 분석하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.15-15
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• 2012

Mg(1-4)Zn 이원계 압출재 및 Mg5Sn(1-4)Zn 삼원계 압출재의 부식거동을 3.5 % NaCl 용액에서 다양한 전기화학기법을 이용하여 평가하였다. 이원계 합금에 대한 연구결과, Zn 함량 증가에 따라 Mg 모재의 부동태화가 촉진되었고 동시에 수소발생속도가 증가하였으며 그 결과 부식전위의 상승이 관찰되었다. 그러나 Zn 함량 증가에 따른 부동태화 효과보다 수소발생 증가 효과가 우세하므로 결과적으로 Zn 함량 증가에 따라 부식속도는 증가하였다. Mg5Sn(1-4)Zn 삼원계 합금에 대한 부식시험 결과, Mg5Sn2Zn 합금이 가장 낮은 부식속도 및 우수한 부동태화를 나타내었으며 이는 합금원소 Sn의 수소발생속도 감소효과와 합금원소 Zn의 부동태화 효과의 상호작용에 의한 것으로 사료된다.

• Journal of Sensor Science and Technology
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• v.31 no.6
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• pp.455-460
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• 2022

Brush-like ZnO hierarchical nanostructures decorated with MgxZn1-xO (x = 0.1, 0.2, 0.3, 0.4, and 0.5) were fabricated and examined for application to a gas sensor. They were synthesized using vapor phase growth (VPG) on indium tin oxide (ITO) substrates. To generate electronic accumulation at ZnO surface, MgZnO nanoparticles were prepared by sol-gel method, and the ratio of Mg and Zn was adjusted to optimize the device for NO₂ gas detection. As the electrons in the accumulation layer generated by the heterojunction reacted faster and more frequently with the gas, the sensitivity and speed improved. When tested as sensing materials for gas sensors at 100 ppm NO₂ at 300℃, these MgZnO decorated ZnO nanostructures exhibited an improvement from 165 to 514 times compared to pristine ZnO. The response and recovery time of the MgZnO decorated ZnO samples were shorter than those of the pristine ZnO. Various analyzing techniques, including field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray powder diffraction (XRD) were employed to confirm the growth morphology, atomic composition, and crystalline information of the samples, respectively.

• Korean Journal of Materials Research
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• v.7 no.11
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• pp.1012-1017
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• 1997

Mg-Zn-Ca합금의 잉곳트는 BN을 내벽에 바른 4x$10^{-5}$Torr의 진공의 석영관내에서 제조하였다. Mg-Zn합금계의 입자미세화를 위하여 0.5-5wt.%조성범위의 Ca를 첨가하였다. 제조된 합금을 용체화처리한 후 결정립크기와 경도를 측정하였다. Mg-6wt.%Zn합금의 입자미세화효과는 Ca가 1.5wt%첨가 될 때 최적의 조건이었다. Mg-6wt.% Zn과 Mg-6wt.% Zn-2wt.% Ca및 Mg-6wt.% Zn-1.5wt.% Si합금을 시효처리하여 시효거동을 조사하였다. 입자미세화에 의한 경도증가효과는 Mg-Zn-Ca합금계에서 크게 나타났으며 시효에 의한 경도증가효과는 Mg-Zn-Si합금계에서 크게 나타났다. Mg-6wt.%Zn합금의 부식전류밀도는 0.5wt.% Ca의 조성에서 감소되었다.

• Clean Technology
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• v.21 no.1
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• pp.39-44
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• 2015

This study investigated the effects of six metal oxide nanoparticles (NPs: CuO, NiO, TiO₂, Fe₂O₃, Co₃O₄, ZnO) on seed germination and germination index (G.I) for five types of seeds: Brassica napus L., Malva verticillata L., Brassica olercea L., Brassica campestris L., Daucus carota L. NPs of CuO, ZnO, NiO show significant toxicity impacts on seed activities [CuO (6-27 mg/L), ZnO (16-86 mg/L), NiO (48-112 mg/L)], while no significant effects were observed at > 1000 mg/L of TiO₂, Fe₂O₃, Co₃O₄. Tested five types of seed showed different sensitivities on seed germination and root activity, especially on NPs of CuO, ZnO, NiO. Malva verticillata L. seed was highly sensitive to toxic metal oxide NPs and showed following EC₅₀s : CuO 5.5 mg/L, ZnO 16.4 mg/L, NiO 53.4 mg/L. Mostly following order of toxicity was observed, CuO > ZnO > NiO > Fe₂O₃ ≈ Co₃O₄ ≈ TiO₂, where slightly different toxicity order was observed for carrot, showing CuO > NiO ≈ ZnO > Fe₂O₃ ≈ Co₃O₄ ≈ TiO₂.

• Journal of Korea Foundry Society
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• v.30 no.4
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• pp.137-141
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• 2010

The effects of Zn amounts on the castability and tensile properties of Al-Zn-Mg-Cu alloys were investigated for development of high strength die casting aluminium alloys. Al-Zn-Mg-Cu alloys with 3.5% Zn showed high cast cracking tendency and poor mold filling behaviour. Al-Zn-Mg-Cu alloys with 5wt% Zn and 7wt% Zn had the tensile strengths of 300~400MPa and the elongations of 2~18%. The effect of Zn on the tensile strength of Al-Zn-Mg-Cu alloys was insignificant, but Al-Zn-Mg-Cu alloy with high Zn amount had lower elongation.

• Journal of Surface Science and Engineering
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• v.47 no.6
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• pp.330-334
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• 2014

In this study, the Zn-Mg alloy coatings with various Mg contents were deposited using an unbalanced magnetron sputtering process. Their surface microstructure, chemical composition, phase, and corrosion property were investigated. The microstructure of the Zn-Mg coatings changed from porous microstructure to dense one with increasing Mg contents in the coatings. As Mg contents in coatings increased, intermetallic phases such as $Mg_2Zn_{11}$ and $MgZn_2$ were detected from X-ray diffraction (XRD) results. The corrosion resistance of the Zn-Mg alloy coatings was investigated quantitatively using electrochemical impedance spectroscopy (EIS) measurement with 3.5% NaCl solution. The results of EIS measurement showed that the charge transfer resistance and the phase angle of the Zn-Mg alloy coatings were increased from $162.1{\Omega}{\cdot}cm^2$ to $558.8{\Omega}{\cdot}cm^2$ and from about $40^{\circ}$ to $60^{\circ}$ with increasing Mg contents from 5.1 wt.% to 15.5 wt.% in the coatings. These results demonstrate that the Zn-Mg coatings with increasing Mg contents showed an enhanced corrosion resistance.

• Korean Journal of Materials Research
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• v.25 no.6
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• pp.269-273
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• 2015

The effect of adding Ca on the microstructural and mechanical properties of as-cast Mg-11Li-3Zn-1Sn(wt%) alloys were investigated. Mg-11Li-3Zn-1Sn-0.4Mn with different Ca additions (0.4, 0.8, 1.2 wt%) were cast under an $SF_6$ and $Co_2$ atmosphere at $720^{\circ}C$. The cast billets were homogenized at $400^{\circ}C$ for 12h and extruded at $200^{\circ}C$. The microstructural and mechanical properties were analyzed by OM, XRD, SEM, and tensile tests. The addition of Ca to the Mg-11Li-3Zn-1Sn-0.4Mn alloy resulted in the formation of $Ca_2Mg_6Zn_3$, MgSnCa intermetallic compound. By increasing Ca addition, the volume fraction and size of $Ca_2Mg_6Zn_3$ with needle shape were increased. This $Ca_2Mg_6Zn_3$ intermetallic compound was elongated to the extrusion direction and refined to fine particles due to severe deformation during hot extrusion. The elongation of the 0.8 wt% Ca containing alloy improved remarkably without reduction strength due to the formation of fine grain and $Ca_2Mg_6Zn_3$ intermetallic compounds by Ca addition. It is probable that fine and homogeneous $Ca_2Mg_6Zn_3$ intermetallic compounds played a significant role in the increase of mechanical properties.