• 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 Nutrition and Health
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• v.21 no.5
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• pp.317-323
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• 1988

Mean daily excretion of Ca, P, and Fe were measured in 49 healthy young Koreans(23 males and 26 females) form urine and feces samples cellected for three days. Dietary intakes of the subjects during the study periods were calculated from intake records. Main results of the study are as following: 1) Mean daily urinary, fecal, and total Ca excretions were 162$\pm$20mg, 346$\pm$39mg, and 508$\pm$50mg, respectively in males and 154$\pm$16mg, 262$\pm$26mg, and 416$\pm$24mg, respectively in females. The mean values of the two groups were not significantly different. 2) Mean daily urinary, fecal, and total P excretions were 751$\pm$45mg, 384$\pm$26mg and 1135$\pm$56mg, respectively in males and 552$\pm$29mg, 335$\pm$34mg and 894$\pm$50mg, respectively in females. Urinary and total P excretion in males were significantly higher than females(p<0.01), but such differences disappeared when the excretions were calculated per kg body weight. 3) mean daily fecal Fe excretions were 12.8$\pm$0.9mg in males and 10.1$\pm$0.8mg in females. The mean value in males was significantly higher than that in females(p<0.05) but when calculated per kg body weight, both groups excreted 0.2mg/kg body weight. 4) Mean daily intake levels of the minerals estimated from three day food intake records were Ca 543mg, P 1136mg, and Fe 14.3mg in males and Ca 533mg, P 869mg, Fe 10.8mg in females. These intake levels seem to be sufficient to supply the daily losses of the study subjects except P in females. However, the problem of estimating dietary intake levels by food intake record should be recognized. Especially females in the study are in menstration age and their Fe losses in the menstration (estimated to be 0.5mg of available Fe per day) should be also supplied in the diet.

• Korean Journal of Metals and Materials
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• v.48 no.8
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• pp.765-774
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• 2010

Oxygen equilibrium and the solubility of MgO have been measured in the $CaO-Fe_tO-MgO-SiO_2({\leq}5mass%)-{\Sigma}M_xO_y$ slag in equilibrium with liquid iron in the temperature range of 1550 to $1700^{\circ}C$. The effect of oxides on the MgO solubility, and a method for calculating the solubility of MgO using slag composition and temperature,were discussed. The solubility of MgO is increased with increasing temperature and $Fe_tO$ content, and with decreasing basicity (C/S). The effect of ${\Sigma}M_xO_y$ on the solubility of MgO is a dilution effect due to the increase in slag volume. The activity and activity coefficient of $Fe_tO$ decreased with increasing basicity (B). The effect of temperature on the activity was negligible. The value of ${\rho}=Fe^{3+}/Fe^{2+}$ increased with the increase of the slag basicity (B") and the decrease of the $Fe_tO$ content in the slag.

• Journal of Magnetics
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• v.7 no.4
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• pp.132-137
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• 2002

The electronic structures and magnetism of the non-oxide perovskite MgCFe$_3$(001) surface were investigated by using the all-electron full-potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA). We considered both of the MgFe terminated (MgFe-Term) and the CFe terminated (CFe-Term) surfaces. We found that the minority spin d-bands of Fe(S) of the MgFe-Term are strongly localized and Fermi level (EF) lies just below the sharp peak of the minority spin d-band of Fe(S), while the minority spin d-bands of Fe(S) of the CFe-Term are not localized much and Fermi level (E$_F$) lies in the middle of two peaks of the minority spins. The majority Fe(S) d-band width of MgFe- Term is narrower than that of the CFe-Term. It is found that the magnetic moment of Fe(S) of the MgFe- Term is 2.51 ${\mu}$$_B$, which is much larger than that of 1.97 ${\mu}$$_B$ of the CFe-Term.

• Journal of the Korean Institute of Navigation
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• v.22 no.4
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• pp.69-75
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• 1998

The super wideband electromagnetic wave absorber in RF-A-PF type has been proposed, which can be used for an anechoic chamber, wall material to prevent TV ghost, etc, In this paper, $Ni_x-Mg_{0.1}-Zn_(1-x-0.1){\cdot}Fe_2O_4$ Ferrite Powder has been fabricated. Using this, then, [$Ni_x-Mg_{0.1}-Zn_(1-x-0.1){\cdot}Fe_2O_4$-Rubber composite for RF-layer in the RF-A-PF type absorber has been fabricated and its characteristics has been analyzed. As a result, it has been shown that the $Ni_x-Mg_{0.1}-Zn_(1-x-0.1){\cdot}Fe_2O_4$-Rubber composit with the quantity $_x$ of $Ni_x$ between 0.5 and 0.6 is suitable for the RF-layer in the case of which the grain size is sub-micrometer order.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.5
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• pp.447-453
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• 1999

Congruent $LiNbO_3$ crystals with doped Mg and codoped with Mn or Fe were grown by the Czochralski method. It is known that the physical properties of $LiNbO_3$ depend strongly on the addition of Mg and transition metals. This is established by studying the following properties; XRD patterns, the phase transition temperature, energy of the fundamental absorption edge, the shape of the absorption band of the $OH^-$ vibration and lines of the ESR of $Fe^{3+},\; Mn^{2+}$. The position of the UV absorption edge and the shape and peak point of the absorption band of the $OH^-$ vibrational band changed monotonously up to a critical concentration of $Mg^{2+}$ ions. The mechanism of the incorporation of Mg ions changes at this concentration. The transition temperature was estimated by measuring the dielectric temperature behavior up to $1230^{\circ}C$ in a frequency range of 100Hz to 10MHz. EPR of $Mn^{2+}\;and\; Fe^{3+}$ ions were employed to investigated the Mg doping effects in the $LiNbO_3$ crystal. The increase of linewidths and the asymmetry of signals were observed in all crystals. New signals of $Fe^{3+}$ arising from the new centers were observed I the heavily Mg-doped crystals.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.2
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• pp.152-164
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• 1995

$xPb(Fe_{1/2}Nb_{1/2})O_3 - (1 - x)Pb(Mg_{1/3}Nb_{2/3})O_3$ powders were synthesized by the molten salt synthesis method using the NaC!- KCI flux with 1 : 1 molar ratio, and their powders and dielectric properties were investigated. The synthesized powders showed less agglomerated shape with the average particle size of less than $2 \mu\textrm{m}$. The composition $x0.3Pb(Fe_{1/2}Nb_{1/2})O_3-0.7Pb(Mg_{1/3}Nb_{2/3})O_3$ could be sintered at $1000{\times}C$ and its dielectric constnat was over 11, 000.

• Journal of the Korean Ceramic Society
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• v.45 no.7
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• pp.418-422
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• 2008

The preparation of FeB by SHS in $B_2O_3-Mg-Fe-Fe_3O_4$ system was investigated in this study. In the preparation of FeB, the effects of the initial pressure of inert gas in reactor, the content of Mg and $Fe_3O_4$ in mixture on the reactivity and reaction products was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 25 atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 25 atm, the optimum composition for the preparation of pure FeB was $1.5B_2O_3$+3.43Mg+ 1.7Fe+$0.1Fe_3O_4$. The FeB synthesized in this condition had an irregular shape and the particle size of $5\;{\mu}m$.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.549-559
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• 2009

The objectives of this study are to investigate the biomineralization of goethite and lepidocrocite formed on the twisted-stalk and the sheathed-filament structure that is suggest microbe origin, and heavy metal in the yellow Fe-hydroxide. On the ratio of Cl and the Cl/Br ratios that are a pollution and non-pollution of groundwaters, it is indicated that the groundwater in this areas were relatively contaminated by human activity. The composition of the yellow Fe-hydroxide consisted mainly of $Fe_2O_3$ and $SiO_2$. The content of $Fe_2O_3$ ranges from 58.57 wt.% to 75.7 3wt.%, and $SiO_2$ content ranges from 5.8 wt.% to 16.17 wt.%. Heavy metal elements such as Zn(max. 6,160 mg/kg), Pb(max. 377 mg/kg), U(max. 503 mg/kg), Cr(max. 203 mg/kg), Cu(max. 77 mg/kg), V(max. 162 mg/kg), Ni(max. 105 mg/kg) were observed to be rich in those yellow Fe-hydroxide. The lath and platy crystals and needle-shaped crystals were clearly observed on the twisted-stalks and sheathed-filaments structure. The goethite, gypsum, and lepidocrocite were identified in the yellow Fe-hydroxide by x-ray powder diffraction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.9
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• pp.760-765
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• 2009

The effects of $Fe_2O_3$ addition on optical and electrical properties of MgO films as a protective layer for AC plasma display panels were investigated. Doped MgO films prepared by the e-beam evaporation have a higher ${\gamma}$ (secondary electron emission coefficient) than pure MgO protective layer. Roughness increased with amount of $Fe_2O_3$ up to 100 ppm and then decreased further addition. These results showed that discharge properties and optical properties of MgO protective layers seemed to be closely related with microstructure factors such as roughness. Good optical and electrical properties of ${\gamma}$ of 0.120, surface roughness of 14.1 nm and optical transmittance of 94.55% were obtained for the MgO + 100 ppm $Fe_2O_3$ protective layer sintered at $1700^{\circ}C$ for 5 hrs.