• Korean Journal of Materials Research
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• v.21 no.4
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• pp.225-231
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• 2011

The effect of ferrous/ferric molar ratio on the formation of nano-sized magnetite particles was investigated by a co-precipitation method. Ferrous sulfate and ferric sulfate were used as iron sources and sodium hydroxide was used as a precipitant. In this experiment, the variables were the ferrous/ferric molar ratio (1.0, 1.25, 2.5 and 5.0) and the equivalent ratio (0.10, 0.25, 0.50, 0.75, 1.0, 2.0 and 3.0), while the reaction temperature ($25^{\circ}C$) and reaction time (30 min.) were fixed. Argon gas was flowed during the reactions to prevent the $Fe^{2+}$ from oxidizing in the air. Single-phase magnetite was synthesized when the equivalent ratio was above 2.0 with the ferrous/ferric molar ratios. However, goethite and magnetite were synthesized when the equivalent ratio was 1.0. The crystallinity of magnetite increased as the equivalent ratio increased up to 3.0. The crystallite size (5.6 to 11.6 nm), median particle size (15.4 to 19.5 nm), and saturation magnetization (43 to 71 $emu.g^{-1}$) changed depending on the ferrous/ferric molar ratio. The highest saturation magnetization (71 $emu.g^{-1}$) was obtained when the equivalent ratio was 3.0 and the ferrous/ferric molar ratio was 2.5.

• Journal of the Korean Magnetics Society
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• v.3 no.2
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• pp.87-93
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• 1993

Iron nitride (Fe-N) magnetic thin films were deposited using a DC magnetron sputtering system. Microstructures and magnetic properties were examined as a function of deposition power and nitrogen gas input ratio. The nitrogen content in the film was found to be the major factor determining the microstructure and the magnetic properties. The films deposited at low nitrogen input ratios have an $\alpha$-Fe structure of which the lattice is expanded due to the nitrogen atoms incorporated at the interstitial sites. As the nitrogen content in the film increases, the degree of lat-tice expansion increases and the value of saturation magnetization decreases linearly. The films with a high degree of lattice expansion give very low values of coercivity, which is attributed to the disturbance of colunmar growth and the decrease of surface roughness. Further increase in the nitrogen input ratio causes the phase transfonnation from $\alpha$-Fe to $Fe_{2-3}N$, resulting in the marked reduction in the saturation magnetization. The phase transformation occurs when, regardless of deposition conditions, the nitrogen content reaches at 15 at.% and the lattice is expanded by 5%.

• Korean Journal of Metals and Materials
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• v.49 no.1
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• pp.17-24
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• 2011

To investigate the relationship between heat treatment in zirconium alloy tubing process and metallurgical characteristics of Zr-1Nb-0.69Sn-0.11Fe alloy tubes, mechanical and oxidation behaviors of tubes heat treated at different temperatures after the final pilgering were investigated. The stress strain curves exhibited the saturation behaviors in all heat treatment conditions ($460{\sim}600^{\circ}C$) in this study with the onset strain of saturation increased with increase of post-pilgering annealing temperature. The strength fell off rapidly with increasing annealing temperature. The ultimate strength of the low tin Zr-1Nb-0.69Sn-0.11Fe alloy with slightly higher iron and oxygen contents in this study was found to be higher than Zr-1Nb-1Sn-0.1Fe alloy. The oxidation experiments in steam condition revealed that the corrosion resistance of low tin Zr-1Nb-0.69Sn-0.11Fe alloy was better than the Zr-1Nb-1Sn-0.1Fe alloy with a higher Sn content. The weight gain of low tin Zr-1Nb-0.69Sn-0.11Fe alloy tubes gradually increased with the increasing annealing temperature possibly due to the decreased Nb content in the matrix because of the formation of ${\beta}-Nb$ particles.

• Journal of Soil and Groundwater Environment
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• v.21 no.6
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• pp.192-203
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• 2016

A field investigation was conducted on an aquifer contaminated with trichloroethylene (TCE) for application of in situ reactive zone treatment using nanosized zero-valent iron (NZVI). The aquifer was an unconfined aquifer with a mean hydraulic conductivity of $5.14{\times}10^{-4}cm/sec$, which would be favorable for NZVI injection. Seasonal monitoring of TCE concentration revealed a presence of non-aqueous phase liquid form of TCE near IW (injection well). The hydrochemical data characterized the site groundwater to be a $Ca-HCO_3$ type. The average value of Langelier Saturation Index of the groundwater was -1.33, which implied that the site was favorable for corrosion of NZVI. Dissolved oxygen (DO) concentration varied between 2.5~11.5 mg/L, which indicated that DO would greatly compete with TCE as an electron acceptor. The hydrogeological and hydrochemical characterization reveals that the time around November would be appropriate for NZVI injection when water level and temperature are relatively high and DO concentration is low.

• Journal of the Korean Magnetics Society
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• v.8 no.1
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• pp.6-12
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• 1998

Fe-N(iron-nitrogen) crystal phases were prepared by nitrogen ion implantation into $\alpha$-Fe foil with Plasma Source Ion Implantation (PSII). Ion implantation time of sample is treated 15 minutes(FeN15) and 30 minutes (FeN30). The nitrogen depth profiles measured by Auger electron spectroscopy (AES) were determined to be about 12000 $\AA$ and 4000 $\AA$ for the samples of FeN15 and FeN30, respectively. The results of vibrating sample magnetometer (VSM) show that the saturation magnetization of the samples of as-implanted FeN15 and FeN30 was higher than that of pure $\alpha$-Fe foil, which may be owing to $\alpha$'-$Fe_8N$ or $\alpha$"-$Fe_{16}N_2$ phases. Accordingly this study shows the possibility of the partial formation of $\alpha$' or $\alpha$" phase in iron nitrogen produced by PSII method.II method.

• Journal of Dairy Science and Biotechnology
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• v.23 no.1
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• pp.1-8
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• 2005

The purpose of this study was to demonstrate biochemical properties and antibacterial activity of lactoferrin(Lf) obtained from the colostrum of Korean native cow. Lactoferrin was isolated from the colostrum of Korean native cow by purification steps using batch extraction, ion exchange chromatography, gel filtration chromatography, affinity chromatography. Other whey protein components that is similar molecular weight and affinity to lactoferrin were gradually removed from crude Korean Native cow's lactoferrin during the purification steps. The molecular weight of the purified Korean native cow's Lf(K-Lf) was 81 kDa, the isoelectric point was 9, and the content of iron was 0.56mg/g, which is indicated that iron saturation of the K-Lf was 40.6%. Amino acid composition and a-helix content were different K-Lf from bovine Lf(B-Lf). Antibacterial activity of E. coli O111 by K-Lf was lower than that of B-Lf. A minimal inhibitory concentration(MIC) of K-Lf and B-Lf was 2.75mg/ml and 1.5mg/ml respectively.

• Food Science of Animal Resources
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• v.25 no.1
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• pp.98-102
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• 2005

The purpose of this study was to demonstrate biochemical properties of lactoferrin (Lf) obtained from the colostrum of Korea native cow. The molecular weight of the purified Korean native cow's Lf (K-Lf) was 81kDa, the isoelectric point was 9, and the content of iron was 0.56 mg/g, which is indicated that iron saturation of the lactoferrin was 40.6%. Amino acid composition and a-helix content were different K-Lf from bovine Lf (B-Lf). Immunological cross reactivity was observed between K-Lf and B-Lf but not between K-Lf and human Lf (H-Lf) by immunodiffusion test and Western blot analysis. Out results indicate that structure of K-Lf is different from that of B-Lf although K-Lf and B-Lf were immunologically cross-reactive.

• Journal of the Korean Society of Food Science and Nutrition
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• v.14 no.2
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• pp.108-116
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• 1985

This study was designed to investigate the nutritional anemic state and hematological findings of children, aged 11 and 12 years, living in Haenam Koon (living at home) and in Mokpo City (living in an orphan asylum) located in Chonnam. The mean red blood cell number of male was higher than female in both groups of living in the rural area and in the city orphan asylum (p<0.01), but the white blood cell count was not significantly different. The levels of average hemoglobin, hematocrit and mean corpuscular hemoglobin concentration of the children in both groups were similar, and 19.8% of children living at home in the rural area and 32.1% of children living in the city orphan asylum were anemic. The mean levels of serum total protein, albumin and A/G ratio in children of both group were not statistically different, and 18.4% of children living at home in the rural area and 13.2% of children living in the city orphan asylum were insufficient in the serum total protein value. The average serum cholesterol level of children living at home in the rural area was higher than that of children living in the city orphan asylum(p<0.01), and that of female living at home was higher than that of male (p<0.05). The mean levels of serum iron, total iron binding capacity and transferrin saturation of children living at home in the rural area were significantly higher than those of children living in the city orphan asylum (p<0.01).

• Journal of the Korean Magnetics Society
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• v.18 no.1
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• pp.14-18
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• 2008

Bismuth-substituted yttrium iron garnet(Bi:YIG) films, which show excellent magnetic and magneto-optical properties as well as low optical losses by optimizing their deposition and post-annealing condition, have been attracting great attention in optical device research area. In this study, the Bi:YIG thick films were deposited with the aerosol deposition method for the final purpose of applying them to optical isolators. Since the aerosol deposition is based on the impact adhesion of sub-micrometer particles accelerated by a carrier gas to a substrate, the flow rate of carrier gas, which is in proportion to mechanically collision energy, should be treated as an important parameter. The Bi:YIG($Bi_{0.5}Y_{2.5}Fe_5O_{12}$) particles with $100{\sim}500$ nm in average diameter were carried and accelerated by nitrogen gas with the flow rate of 0.5 l/min${\sim}$10 l/min. The coercive force decreased from 51 Oe to 37 Oe exponentially with increasing gas flow rate. This is presumably due to the fact that the optimal collision energy results in reduction of impurity and pore, which makes the film to be soft magnetically. The saturation magnetization decreased due to crystallographical distortion of the film with increasing gas flow rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.545-551
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• 2011

Recently, demands for generating high quality tap waters are increasing with high concern of water pollution and corrosion of water pipelines. For the reasons, developing water quality stabilization technique in water purification system is sought rather than replacing to a new pipelines. In this study, high-purity liquid lime($Ca(OH)_2$) was introduced for a water quality stabilization technique in water purification process and simulated water distribution system of pilot-scale size was applied to evaluate anti-corrosion control effect. The effect of anti-corrosion control was calculated in terms of LSI(Langelier Saturation Index) In conclusion, the result of pilot plant showed improvement of corrosiveness by liquid lime($Ca(OH)_2$) with reduction of released iron(Fe). Application of anti-corrosion control technique to the mild steel coupon and the copper coupon were effective by indicating 35.4, 44.5% of improvements. Besides, sample pipes which were treated with liquid lime had formated more thicker layer of corrosion product inside of pipes. As a result, the process of injecting water stabilizer can greatly contribute to the high quality of tap water.