• Korean Journal of Materials Research
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• v.13 no.6
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• pp.365-368
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• 2003

Small amounts of additives such as mol % 0.13 NiO and mol % 0.01 $CaCO_3$were added to Cu-Zn-Mg ferrites. Basic composition of the Cu-Zn-Mg ferrites was $Cu_{Cu}$X/$Fe_{0.054}$ /$Zn_{0.486}$$Mg_{0.407}$ $Fe_{1.946}$ $O_4$(group A) and $Cu_{0.263}$$Fe_{0.027}$ $Zn_{0.503}$ $Mg_{0.262}$ $Fe_{1.973}$ $O_4$(group B). Specimens were sintered at different temperatures (1010, 1030, $1050^{\circ}C$) for 2 hours in air followed by an air cooling. Then, effects of various composition and sintering temperatures on the microstructure and the magnetic properties such as inductions, coercive forces, and initial permeabilities of the Cu-Zn-Mg ferrites were investigated. The average grain size increased with the increase of sintering temperature. The magnetic properties obtained from the aforementioned Cu-Zn-Mg ferrite specimens were 1,724 gauss for the maximum induction, 1.0 oersted for the coercive force, and 802 for the initial permeability. These magnetic properties indicated that the specimens could be utilized as the core of IFT (intermediate frequency transformer) and antenna in the amplitude modulation.

• Journal of the Korean Magnetics Society
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• v.19 no.1
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• pp.12-16
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• 2009

Z-type barium ferrite [($Ba_{3}Co_{0.8}Zn_{1.2}Fe_{24}O_{41}$, $Ba_{3+{\delta}}Co_{0.8}Zn_{1.2}Fe_{24}O_{41}$ ${\delta}$ = 3, 5, 7, 13 wt%. $Ba_{3}Co_{0.8}Zn_{1.2}Fe_{24+{\delta}}O_{41}$ ${\delta}$ = 5, 7, 10 wt% )] were synthesized using co-precipitation method. The microstructure and magnetic properties of synthesized particles were investigated. In all prepared particles M-type Ba ferrite is identified with Z-type Ba ferrite together. It is found that particles having 7 wt% for Ba and 5 wt% for Fe excess addition revealed high saturation magnetization, respectively. All synthesized particles showed relatively high coercivity for device application. This result may be attributed to the contribution of M-type Ba ferrite. Ba and Fe excess addition was not affected to the structural change of CoZnZ Ba ferrite. The certain amount of excess additions of Ba and Fe and the 2 step heat-treatment may be beneficial to the improvement of soft magnetic properties of Z-type barium hexa-ferrite

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.4
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• pp.312-317
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• 2004

High dose ($3{\times}10^{16}cm^{-2}$) implantation of Fe or Ni ions into bulk, single-crystal ZnO substrates was carried out at substrate temperature of ${\sim}350^{\circ}C$ to avoid amorphization of the implanted region. The samples were subsequently annealed at $700^{\circ}C$ to repair some of the residual implant damage. X-Ray Diffraction did not show any evidence of secondary phase formation in the ZnO. The Ni implanted samples remained paramagnetic but the Fe-implanted ZnO showed evidence of ferromagnetism with an approximate Curie temperature of ${\sim}$240K. Preliminary X-Ray Photoelectron Spectroscopy measurements showed the Fe to be ill the 2+ oxidation state. The earrler density in the implanted region still appears to be too low to support carrier-meditated origin of the ferromagnetism and formation of bound magnetic polarons may be one potential explanation for the observed magnetic properties, No evidence of the Anomalous Hall Effect could be found in the Fe-implanted ZnO, but its transport properties were dominated by the conventional or ordinary Hall effect.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.79-87
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• 2010

Field water qualities (temperature, pH, Eh, EC, DO) was monitored by 6 times March to September 2009 on background water (BW) and acid mine drainage (AMD0, AMD1, AMD2 and AMD3 points), and flow rate was measured on AMD0 point. Acid mine drainage flowed out from abandoned Ilgwang mine were high acid waters that lower than pH 3, and Eh component was ranged 400 to 600 mV. EC measured on acid mine drainage were higher over 10 times than background water, DO component was increased by reaction on the air during the water flow from AMD0 point to AMD4 point. Heavy metal concentrations in acid mine drainage were ordered Fe > Cu > Zn > Mn > As > Cd, and Fe concentration was highest for 81.870~474.30 mg/L. Monitoring periods measured maximum concentrations of heavy metals were May for As and Cd, June for Fe, July for Cu, Zn and Mn. The periods measured minimum concentrations were monitored April for Cd and Mn, September for Fe, Cu, Zn and As. Discharge mass of heavy metal components were calculated 53.44 kg for Fe, 6.25 kg for Cu, 5.26 kg for Zn, 2.13 kg for Mn, 0.14 kg for As and 0.04 kg for Cd, respectively. Total discharge mass of heavy metal components were calculated 67.26 kg for 1 day, and Fe component was taken 79% of total mass.

• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.368-376
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• 2009

In this study we investigated and tried to understand problems monitored in an experiment on reactivity of metals in chemistry I. Three problems were discussed. First, the reason that aluminium plate does not react with other metal ions such as zinc, iron and copper was studied and the way to overcome this problem was suggested. Second, the reason that the bubbles were generated when FeS$O_4$(aq) and Zn(s) react was discussed. Third, the precipitates which appeared in the reaction of FeS$O_4$(aq) and Zn(s) were identified. Through reference study and experimental investigation, we could reach the following results. First, aluminium could not react with other metal ions due to the surface oxide layer that is formed very fast and prevents aluminium from reacting with metal ions in solution. This problem could be overcome by allowing a competing reaction of acid and aluminium during the reaction of aluminium and metal ions. Second, the observed bubbles were identified to be hydrogen gas, produced by the reaction between metals and hydronium ion in the solution. Third, black precipitates that were produced on the surface of zinc plate and exhibited magnetic property were characterized to be $Fe_3O_4$(s), and brown precipitates that were produced in the solution phase were to be $Fe_2O_3$(s) by the analysis of X-ray photoelectron spectra.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.6
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• pp.444-448
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• 2010

Based on first-principles calculations, we study the magnetic properties of Co, Ni, Fe, V, and Mn impurities in ZnO. The stabilities of the ferromagnetic state and the magnetic moment of each impurity largely depend on the amount of doped electron or hole. For lightly doped n-type ZnO, it is found that the doping of Ni ions is the most effective for inducing ferromagnetism, while Fe ions show the most stable ferromagnetic couplings for heavily doped n-type samples. The characteristics of the magnetic interactions of Co ions are similar with those of Fe ions, but Co ions require much larger amount of doped electron than Fe ions to show the ferromagnetic couplings. The ferromagnetic coupling between Mn and V ions is unstable in n-type conditions.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.252-253
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• 2009

희생양극으로 많이 활용되고 있는 Zn, Mg 금속은 모재 금속과 갈바닉 쌍을 형성하여 방식체를 보호하게 된다. 본 실험에서는 SPCC 강판위에 Fe+Mg, Fe+Zn 강판을 각각 제작하여 갈바닉 전류와 갈바닉 전위를 측정하였다. 갈바닉 전류는 초기에 금속 표면의 산화피막의 영향으로 큰값을 나타났으나, 시간의 경과에 따라 안정적인 값을 나타냈다. 즉, 가스압의 증가에 따라 제작된 Fe+Mg, Fe+Zn박막의 내식성은 우수하게 나타났고, 가스압이 낮을수록 박막의 내식성은 떨어지는 것으로 나타났다. 갈바닉 전위는 철의 방식전위에 도달하는 시간에 따라 내식성의 우수성을 판단하였다.

• Journal of Powder Materials
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• v.25 no.3
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• pp.208-212
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• 2018

In this paper, a new $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ high entropy alloy (HEA) is identified as a strong candidate for the single face-centered cubic (FCC) structure screened using the upgraded TCFE2000 thermodynamic CALPHAD database. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA is fabricated using the mechanical (MA) procedure and pressure-less sintering method. The $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA, which consists of elements with a large difference in melting point and atomic size, is successfully fabricated using powder metallurgy techniques. The MA behavior, microstructure, and mechanical properties of the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA are systematically studied to understand the MA behavior and develop advanced techniques for fabricating HEA products. After MA, a single FCC phase is found. After sintering at $900^{\circ}C$, the microstructure has an FCC single phase with an average grain size of $18{\mu}m$. Finally, the $Co_{10}Fe_{10}Mn_{35}Ni_{35}Zn_{10}$ HEA has a compressive yield strength of 302 MPa.

• Analytical Science and Technology
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• v.14 no.2
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• pp.140-146
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• 2001

The study was carried out to analyze the pollutants, Fe, Cu, Cr, Zn, Cd for 3 sediments of 5 sites collected from lake in K river basin. 5cm sediment, which is nearly proximated to water from sediment of depth 30cm, showed higher Fe, Cu, Cr, Zn, Cd data than another 5-10cm and 10cm sediment, which is separated from sediment of depth 30cm. Also, 5cm sediment nearly proximated to water showed the following data: Fe, 34.9-39.8mg/L, Cu, 34.5-44.8mg/L, Cr, 68.0-79.2mg/L, Zn, 147.4-126.0mg/L, Cd, 2.2-1.0mg/L, respectively. From this results, we know the fact that the pollution degree of sediment has an effect on the water quality in like and stream.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.3
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• pp.333-337
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• 2009

This study was conducted to determine contents and estimated availabilities of trace minerals (Cu, Fe, Mn, Zn) in soybean sprouts depending on culture periods such as 1, 3 and 5 days. The proportional changes of Cu estimated availability in cotyledon were between 57.31 and 98.34%, between 63.69 and 82.56% for Fe, 99.19 and 99.82% for Mn and 48.60 and 94.56% for Zn, respectively, based on dry matter. The estimated availabilities of Cu, Fe, Mn, and Zn in hypocotyl were between 34.63 and 56.0%, 20.74 and 40.33%, 86.5 and 95.88%, and 96.11 and 96.61%, respectively, on dry matter basis.