• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.231-236
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• 2008

Response surface methodology (RSM) was used for the analysis and optimization of the production process of strawberry Kochujang. Experiments were carried out according to a central composite design, selecting strawberry puree content and red pepper powder content as independent variables and soluble solids content, moisture content, water activity, color characteristics ($L^*-$, $a^*-$, and $b^*$-values) as response variables. The polynomial models developed by RSM were highly effective for describing the relationships between the study factors and the responses. Kochujang containing a higher amount of red pepper powder had a higher soluble solids content; on the contrary, soluble solids content decreased with the increase in the strawberry puree content in the sample. Moisture content increased with increased strawberry puree content but decreased with increased red pepper powder content. Water activity increased with the increase in strawberry puree content in the sample but was less affected by the amount of red pepper powder content. Decreases in $L^*$-values with increasing amount of red pepper powder were noted. $a^*$-values decreased with the increases in red pepper powder content but increased with the increase in strawberry puree content in the Kochujang formulation. $b^*$-values decreased with the increases in red pepper powder content but was less affected by the strawberry puree content. Overall optimization, conducted by overlaying the contour plots under investigation, was able to point out an optimal range of the independent variables within which the six responses were simultaneously optimized. The point chosen as representative of this optimal area corresponded to strawberry puree content=14.36% and red pepper powder content=11.33%, conditions under which the model predicted soluble solids content=$59.31^{\circ}Brix$, moisture content=45.30% (w.b.), water activity=0.758, $L^*$-value=24.81, $a^*$-value=7.250, and $b^*$-value=10.19.

• Journal of Powder Materials
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• v.17 no.2
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• pp.154-159
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• 2010

In this study, the sintering behavior of (Nd, Dy)-Fe-B powder which fabricated by strip-casting was investigated with various sintering temperatures and holding times. The relative density over 99% could be obtained by both sintering at $1070^{\circ}C$ for 1h and sintering at $970^{\circ}C$ for 20h. The grain growth was observed in sintered specimen at $1050^{\circ}C$ compared to one at $970^{\circ}C$. The isothermal sintering process below $1000^{\circ}C$ led to suppress grain growth showing the improved magnetic properties. The phase transformation of Nd-rich was confirmed by X-ray diffraction pattern.

• Journal of Powder Materials
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• v.19 no.1
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• pp.1-5
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• 2012

In order to improve the remanence of (Nd, Dy)-Fe-B sintered magnets, we investigated the influence of compaction conditions such as packing density, applied field and green density on the magnetic properties. While the remanence decreased with increasing the packing density and green density, it increased with the increase of the applied field. In addition, XRD analysis revealed that the remanence was enhanced as the degree of powder alignment was improved. The green density was more influential on the remanence than the packing density and applied field.

• Progress in Superconductivity
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• v.14 no.2
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• pp.116-121
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• 2012

Effect of mixed gas and additional Mg powder in an annealing process of the $MgB_2$ is investigated. Four different type of samples were prepared, each in different annealing environment of Ar, $Ar+4%H_2$, Ar with Mg powder and $Ar+4%H_2$ with Mg powder. Different annealing environment did not affect the electron-phonon interaction which is reflected from the same superconducting transition of 36.6 K for all samples. The reducing effect of hydrogen is clearly depicted from the presence of excess Mg in sample synthesized in $Ar+4%H_2$ gas implying the reduced rate of reaction between Mg and B. This has manifested itself in terms of slightly increased high-field critical current density of the sample. In contrast, the sample synthesized in $Ar+4%H_2$ with Mg powder, has shown overall enhancement in the superconducting properties as presented by higher diamagnetic saturation and critical current density.

• Journal of Powder Materials
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• v.16 no.2
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• pp.110-114
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• 2009

Mechanical coating process was applied to form 89 %-hydrolyzed poly vinyl alcohol (PVA) onto boron carbide ($B_4C$) nanopowder using one step high energy ball mill method. The polymer layer coated on the surface of B4C was changed to glass-like phase. The average particle size of core/shell structured $B_4C$/PVA was about 50 nm. The core/shell structured $B_4C$/PVA was formed by dry milling. However, the hydrolyzed PVA of $98{\sim}99%$ with high glass transition temperature ($T_g$) was rarely coated on the powder. The $T_g$ of polymer materials was one of keys for guest polymer coating on to the host powder by solvent free milling.

• Food Science and Preservation
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• v.22 no.6
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• pp.838-844
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• 2015

The purpose of this study was to perform a functional components analysis and investigate the physical properties of powders made from the stems or fruit of freeze-dried Cheonnyuncho cactus (Opuntia humifusa). The functional components analysis showed that the stem and fruit powders han vitamin C levels of 42.14 mg and 105.21 mg, respectively. The stems powder contained more lutein than the fruit powder. The fruit powder contained more vitamin C than the stem powder. The SDF (soluble dietary fiber) and IDF (insoluble dietary fiber) in the stem powder were 45.24% and 22.15%, respectively, which were higher then the values for the fruit powder. The stem and fruit powders contained 19.30 mg/g and 25.10 mg/g of crude saponin, respectively. The pH of the stem and fruit powders was 5.34 and 5.07, respectively, both indicating low acidity. The L, a and b values of the stem powder color were 78.28, -3.71, and 19.19, respectively. The L, a and b values of the fruit powder color were 55.56, 24.84, and -3.18, respectively. The stems powder had a higher bulk density, water holding capacity, and swelling power than those of the fruit powder, but water-retaining capacity of the stem powder was lower than that of the fruit powder. In addition, the stems powder had a higher viscous material content and water uptake compared to the fruit powder. Based on the above results, we determined that Cheonnyuncho (Opuntia humifusa) powder had potentially useful functional components and physical properties.

• 연구논문집
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• s.34
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• pp.121-129
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• 2004

The influence of powder size and ball-milling time on the magnetic properties of $Fe_{73}Si_{16}B_7Nb_3Cu_1$ nanocrystalline alloy powder was investigated. Flake-shaped powders were produced by pulverizing the ribbons annealed at $550^\circC$ for 1 hour. The powders were classified and consolidated into core shapes at a pressure of 18ton/$cm^2$. The initial permeability at 100kHz of the inductor core produced using $53-75\mum$ powders showed the highest value although its consolidated density showed the lowest one. The reason for the result is due to the cracking of the particles larger than $75\mum$ during the consolidation process. The ball-milling of powders for 2-4 hours improved the consolidation density and the initial permeability of the cores. The intrinsic coercivity of the powder decreased as well, resulting from the stress relief of the powder by a short-time milling.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.10b
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• pp.14-15
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• 1998

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.11a
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• pp.32-32
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• 2002

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.04a
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• pp.50-50
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• 2003