• Journal of Powder Materials
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• v.24 no.2
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• pp.87-95
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• 2017

Lithium silicate, a lithium-ion conducting ceramic, is coated on a layer-structured lithium nickel manganese oxide ($LiNi_{0.7}Mn_{0.3}O_2$). Residual lithium compounds ($Li_2CO_3$ and LiOH) on the surface of the cathode material and $SiO_2$ derived from tetraethylorthosilicate are used as lithium and silicon sources, respectively. Powder X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy analyses show that lithium silicate is coated uniformly on the cathode particles. Charge and discharge tests of the samples show that the coating can enhance the rate capability and cycle life performance. The improvements are attributed to the reduced interfacial resistance originating from suppression of solid-electrolyte interface (SEI) formation and dissolution of Ni and Mn due to the coating. An X-ray photoelectron spectroscopy study of the cycled electrodes shows that nickel oxide and manganese oxide particles are formed on the surface of the electrode and that greater decomposition of the electrolyte occurs for the bare sample, which confirms the assumption that SEI formation and Ni and Mn dissolution can be reduced using the coating process.

• Journal of Powder Materials
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• v.4 no.1
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• pp.26-41
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• 1997

The powder metallurgy (P/M) processed 2009 and 2124 Al composites reinforced with SiC particulates were studied by focusing on the effect of consolidation temperature on the microstructural and mechanical Properties. The mechanical properties such as tensile properties and microhardness of the second phases were analysed in relation to the microstructures observed by a SEM and an optical microscope. The in situ fracture process study using SEM showed that the grain refinement and the removal of manganese-containing particles often observed in the 2124 Al-${SiC}_{p}$ composites were important for the improvement of the mechanical properties. This study offers an optimum consolidation temperature for the control of the manganese-containing particles in the 2124 Al-${SiC}_{p}$ composites that yields mechanical properties higher than those of the 2009 Al-${SiC}_{p}$ composites.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.933-934
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• 2006

The present study examines the sintering behaviour and effect of manganese addition both mechanically-blended and mechanically alloyed on Cr-Mo low alloyed steels to enhance the mechanical properties. Mn sublimation during sintering provides some specific phenomena which facilitate the sintering of alloying elements with high oxygen affinity. First step is the optimization of milling time to attain a master alloy with 50% of Mn which is diluted in Fe-1.5Cr-0.2Mo water atomized prealloyed powder by normal mixing. These mixtures are pressed to a green density of $7.1g/cm^3$ and sintered at $1120^{\circ}C$ in $90N_2-10H_2$ atmosphere.

• Journal of Nutrition and Health
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• v.40 no.8
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• pp.769-778
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• 2007

Using ICP-AES, we analyzed manganese content in 366 foods consumed frequently by Koreans. For the analysis, it was included a total of 366 foods such as 51 kinds of grains, 7 kinds of potatoes and starches, 7 kinds of sugars and sweeteners, 12 kinds of legumes, 11 kinds of nuts and seeds, 68 kinds of vegetables, 7 kinds of mushrooms, 33 kinds of fruits, 13 kinds of meats, 4 kinds of eggs, 48 kinds of fishes and shellfishes, 7 kinds of seaweeds, 16 kinds of milks, 8 kinds of oils and fats, 27 kinds of beverages, 34 kinds of seasonings, 13 kinds of processed foods and others. Among the grains, starches and sugars, manganese content of rice was 0.745 mg/100g. As for legumes, the content of manganese in soybean milk was 0.033 mg/100g and in black beans was 4.075 mg/100g. In nuts and seeds, the content of manganese in gingko nuts was 0.268 mg/100g while that in pine nuts was 8.872 mg/100g. Among the vegetables, manganese contents were 0.061 mg/100g in cherry tomato and 14.017 mg/100g in ginger. In mushrooms, the highest manganese content was displayed in ear mushroom at 10.382 mg/100g. Dried jujube and shrimp were found to be the fruits and fishes with high manganese contents at 2.985 mg/100g and 3.512 mg/100g, respectively. Among dairy foods, oils and beverages, manganese content was the highest in instant coffee powder at 2.577 mg/100g. Seasonings and processed foods posted 0.010 mg/100g in Sagolgomtang, instant soup and 23.846 mg/100g in pepper. In a furture, more various food for manganese content needs to be analyzed and a reliable food database should be compiled from the findings of researches in order to estimate manganese consumption accurately.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.403-404
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• 2006

Sintered materials have been applied widely in Valve Seat Inserts (VSI). The demands for VSIs are not only good heat and wear resistance but also good machinability. The sintered materials, which are made of a mixture of manganese containing iron powder and certain types of sulfide powder, have superior machinability due to precipitation of the fine MnS particles in the matrix. This report introduces a new VSI material, which has both superior machinability, and wear resistance due to applies of this "MnS precipitation" technique.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1220-1221
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• 2006

[ $LiMn_2O_4$ ] powders for lithium ion batteries were synthesized from two separate raw material pairs of LiOH/MnO and $LiOH/MnO_2$. The powders prepared at 780 and $850^{\circ}C$ and their difference of electrochemical properties were investigated. Both powders calcined at 780 and $850^{\circ}C$ were composed of a single-phase spinel structure but those treated at $850^{\circ}C$ showed a lower intensity ratio of $I_{311}$ to $I_{400}$, a slightly larger lattice parameter, and an increased discharge capacity by 10% under $3.0{\sim}4.3V$ voltage range. The XPS study on the oxidation states of manganese repealed that powders made from LiOH/MnO had less $Mn^{3+}$ ion and gave better battery performances than those from $LiOH/MnO_2$.

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.201-205
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• 2012

The effects of various manganese precursors for the low-temperature selective catalytic reduction (SCR) of $NO_x$ were investigated in terms of structural, morphological, and physico-chemical analyses. $MnO_x/TiO_2$ catalysts were prepared from three different precursors, manganese nitrate, manganese acetate(II), and manganese acetate(III), by the sol-gel method. The manganese acetate(III)-$MnO_x/TiO_2$ catalyst tended to suppress the phase transition from the anatase structure to the rutile or the brookite after calcination at $500^{\circ}C$ for 2 h. It also had a high specific surface area, which was caused by a smaller particle size and more uniform distribution than the others. The change of catalytic acid sites was confirmed by Raman and FT-IR spectroscopy and the manganese acetate(III)-$MnO_x/TiO_2$ had the strongest Lewis acid sites among them. The highest de-NOx efficiency and structural stability were achieved by using the manganese cetate(III) as a precursor, because of its high specific surface area, a large amount of anatase $TiO_2$, and the strong catalytic acidity.

• Resources Recycling
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• v.11 no.1
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• pp.3-8
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• 2002

In order to make the high purity Mn$_3$O$_4$powder for the raw material of soft ferrite, Mn is extracted from the dust and the extracted solution is refined. The dust is generated in producing a medium-low carbon ferromanganese and contains 90% Mn$_3$O$_4$. Mn$_3$O$_4$in the dust was reduced into MnO by roasting with charcoal. Injection of the 180g/L of the reduced dust into 4N HCI solution increased pH of the leaching solution higher than 5 and then a ferric hydroxide was precipitated. Because the ferric hydroxide co-precipitates with Si ion etc, Fe and Si ion was removed from the solution and the about 10% Mn solution was obtained. The solution was diluted with water to Mn-15000 ppm and $NH_4$F was injected into the diluted solution at $70^{\circ}C$ to the F-3000 ppm. As a result, Ca ion is precipitated as $CaF_2$and the residual concentration of Ca was 14 ppm. Injection of the equivalent (NH$1.5M_4$)$_2$$CO_3$solution as 2 L/min at $25^{\circ}C$ into the above solution precipitated a fine and high purity $MnCO_3$powder. The deposition was filtrated and roasted at $1000^{\circ}C$ for 2 hours. As a result, $MnCO_3$powder is converted into $Mn_3$$O_4$powder and it had $8.2\mu$m of median size. The final production is above 99% $Mn_3$$O_4$powder and it satisfied the requirement of high purity $Mn_3$$O_4$powder for a raw material of soft ferrite.

• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.315-320
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• 2006

manganese oxides have been prepared by Chimie Douce redox reaction between permanganate and chalcogen element fine powder under acidic condition (pH = 1). According to powder X-ray diffraction analyses, the S- and Se-doped manganese oxides are crystallized with layered birnessite and tunnel-type -MnO2 structures, respectively. On the contrary, Te-doped compound was found to be X-ray amorphous. According to EDS analyses, these compounds contain chalcogen dopants with the ratio of chalcogen/manganese = 4-7%. We have investigated the chemical bonding character of these materials with X-ray absorption spectroscopic (XAS) analysis. Mn K-edge XAS results clearly demonstrated that the manganese ions are stabilized in octahedral symmetry with the mixed oxidation states of +3/+4. On the other hand, according to Se K- and Te L1-edge XAS results, selenium and tellurium elements have the high oxidation states of +6, which is surely due to the oxidation of neutral chalcogen element by the strong oxidant permanganate ion. Taking into account their crystal structures and Mn oxidation states, the obtained manganese oxides are expected to be applicable as electrode materials for lithium secondary batteries.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.4
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• pp.447-452
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• 2007

This study was peformed to estimate manganese intake and the major food source of manganese in Korean adults. The 354 subjects aged over 20 years were measured anthropometrics and dietary intake using 24-hour recall method. Daily intake and the major food sources of manganese were calculated using manganese database of food composition tables in Korea, USA and Japan. The average age, height, weight and BMI were 54.6years, 165.7cm, 67.2kg and $24.5kg/m^2$ for men and 53.8 years, 153.7cm, 59.1kg and $24.9kg/m^2$ for women, respectively. The daily energy and manganese intake of men were significantly higher than those of women (1740.9 kcal vs. 1432.6 kcal; p<0.001, 3.7mg vs. 3.2mg; p<0.01). However, daily manganese intake per 1000kcal between men and women was not significantly different (2.2mg/1000kcal vs. 2.3mg/1000kcal). Daily manganese intakes from each food group were 1.9mg from cereals, 0.5mg from vegetables, 0.4mg from pulses and 0.2mg from seasonings. The 20 major food sources of dietary manganese were rice, soybean, sorghum, Kimchi, tobu, wheat flour, red pepper powder, small red bean, glutinous millet, soybean paste, potato, Ramyeon, green pepper, noodle, buckwheat Naengmyeon, soybean sprout, laver, watermelon, perilla seeds powder and soy sauce. Manganese intake from these 20 foods was 74.0% of the total dietary manganese intake. In conclusion, daily manganese intake of the subject was 3.4mg (2.2mg/1000 kcal) and met adequate intake of manganese. The mai or food sources of manganese were cereals, pulses, and vegetables such as rice, soybean, sorghum, Kimchi and tobu.