• Textile Coloration and Finishing
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• v.24 no.1
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• pp.18-26
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• 2012

In this work, colorants extraction process from gromwell was studied for making powder form of colorants by solving the high viscosity problem of gromwell extracts. In order to do that, sugar extracted together with colorants must be pre-extracted. For sugar decomposition, gromwell roots were pretreated with various enzyme solutions. The total sugar content of pre-extract with enzyme solution was measured. Accordingly, the effects of enzyme type and pretreatment condition on sugar decomposition were investigated to find appropriate enzyme(amylase, hemicellulase, pectinase) and enzyme activity (100~1000unit), pre-extracted time(3~24hr). Color characteristics and dye uptake of dyed fabrics were evaluated. Gromwell colorants were assessed for their potential antimicrobial activities, which possibly expand their end use as functional pigments. The efficiency of removing sugar was increased in the order of hemicellulase, pectinase, amylase, $H_2O$. Gromwell colorants powder yield was in the range of 4.4% to 9.8% depending on pretreatment enzyme. Gromwell colorants produced RP color on the silk and wool fabrics with good dye uptake. Antimicrobial activity of gromwell colorants will greatly increase its potentiality for applying as functional natural colorants in the future.

• Journal of Powder Materials
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• v.25 no.1
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• pp.36-42
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• 2018

In order to expand the application of oxide dispersion-strengthened (ODS) steel, a composite material is manufactured by adding mechanically alloyed ODS steel powder to conventional steel and investigated in terms of microstructure and wear properties. For comparison, a commercial automobile part material is also tested. Initial microstructural observations confirm that the composite material with added ODS steel contains i) a pearlitic Fe matrix area and ii) an area with Cr-based carbides and ODS steel particles in the form of a $Fe-Fe_3C$ structure. In the commercial material, various hard Co-, Fe-Mo-, and Cr-based particles are present in a pearlitic Fe matrix. Wear testing using the VSR engine simulation wear test confirms that the seatface widths of the composite material with added ODS steel and the commercial material are increased by 24% and 47%, respectively, with wear depths of 0.05 mm and 0.1 mm, respectively. The ODS steel-added composite material shows better wear resistance. Post-wear-testing surface and cross-sectional observations show that particles in the commercial material easily fall off, while the ODS steel-added material has an even, smooth wear surface.

• Journal of Magnetics
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• v.21 no.2
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• pp.192-196
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• 2016

The Fe-Si-B-Nb-Cu alloys containing Ca and Al were rapidly solidified to thin ribbons by melt-spinning. The ribbons were ball-milled to make powders, and then mixed with 1 wt.% water glass and 1.5 wt.% lubricant. The mixed powders were burn-off, and then compacted to form toroidal-shaped cores, which were heat treated to crystallize the nano-grain structure and to remove residual stress of material. The characteristics of the powder cores were analyzed using a differential scanning calorimetry (DSC) and a B-H meter. The microstructures were observed using transmission electron microscope (TEM). The optimized soft magnetic properties (${\mu}_i$ and $P_{cv}$) of the powder cores were obtained from the Ca and Al containing alloys after annealing at $530^{\circ}C$ for 1 h. The core loss of Fe-Si-B-Nb-Cu-based powder cores was reduced by the addition of Ca element, and the initial permeability increased due to the addition of Al element.

• Journal of the Korean Society of Food Culture
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• v.24 no.3
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• pp.321-330
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• 2009

This study was conducted to develop a recipe for a nutritional cookie containing chungkukjang powder that had a composition of ingredients and a texture that resulted in a high preference by all age groups. Wheat flour was partially substituted with chungkukjang powder to reduce its content. Response surface methodology was then used to analyze the measured results, which showed 16 experimental points including 2 replicates for chungkukjang powder, butter and sugar. The compositional and functional properties were then measured, after which these values were applied to a mathematical model. A canonical form and perturbation plot revealed the influence of each ingredient on the final mixture. The results of the sensory evaluation showed significant values with respect to color (p<0.01), texture (p<0.05) and overall quality (p<0.05). Taken together, the results of this study indicated that the optimal ratio was 26.57 g of chungkukjang powder, and 82.08 g of butter for every 52.36 g of sugar. The physical and chemical sensory measurements were then evaluated by a t-test, and the results revealed significant differences in the flavor of the optimized cookie when compared to the control cookie.

• International Journal of Industrial Entomology and Biomaterials
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• v.48 no.2
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• pp.59-66
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• 2024

The mature Bombyx mori silkworm is recognized as a rich source of several nutrients. A unique steaming process has been developed to enhance the palatability of Bombyx mori silkworm and make it more convenient to consume. Additionally, it has also been freeze-dried into a powder form, which is recognized as a nutritional supplement with many health benefits. Steamed and Freeze-dried Mature Silkworm Powder (SMSP) is said to offer a wide range of benefits, including longevity, improved athletic performance, prevention of alcohol-induced liver fibrosis or tumors, amelioration of fatty liver, prevention of peptic ulcers, regulation of melanin production, and mitigation of Parkinson's and Alzheimer's diseases by improving cognitive function. The nutritional composition of SMSP is particularly high in glycine, alanine and serine. This review aims to summarize the molecular mechanisms underlying the diverse effects induced by these key components of SMSP. Such elucidation will enhance the credibility of future studies on SMSP, which will require more comprehensive analyses. It appears that SMSP represents a natural health supplement that could have a positive impact on global human health while increasing income.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1992.03a
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• pp.59-70
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• 1992

Appropriate yield criteria are necessary to perform computer simulation for densification processes of powder compacts and sintered metals. Various yield functions have been reviewed and a new form for yield criterion has been advanced. The yield criterion satisfies experimental results from combined tension and torsion tests of sintered porous iron specimens.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.47-58
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• 2011

Halogen free intumescent flame retardants(IFRS), such as the mixture of melamine phosphate(MP) and char forming agents(pentaerythritol(PER), di-pentaerythritol(DiPER), tris(2-hydroxyethyl) isocyanurate(THEIC)), were prepared and characterized. Polypropylene(PP)/$IFR_S$ composites were also prepared in the presence of ethylene diamine phosphate(EDAP) as a synergist and used into flame retardant PP powder coatings. Thermoplastic PP powder coatings at 20 wt% flame retardant loading were manufactured by extruded and then mechanical cryogenic crushed to bring them in fine powder form. These intumescent flame retardant powder coatings($IFRPC_S$) were applied on mild steel surface for the purpose of protection and decorative. It is a process in which a $IFRPC_S$ particles coming in contact with the preheated mild steel surface melt and form a thin coating layer. The obtained MP flame retardant was analyzed by utilizing FTIR, solid-state $^{31}P$ NMR, ICP, EA and PSA. The mechanical properties as tensile strength, melt flow index(MFI) and the thermal property as TGA/DTA and the fire safety characteristics as limiting oxygen index(LOI), UL94 test, SEM were used to investigate the effect of $IFRPC_S$. The experimental results show that the presence of $IFR_S$ considerably enhanced the fire retardant performances as evidenced by the increase of LOI values 17.3 vol% and 32.6 vol% for original PP and $IFRPC_S$-3(PP/MP-DiPER/EDAP), respectively, and a reduction in total flaming combustion time(under 15 sec) in UL94 test of $IFRPC_S$. The prepared $IFRPC_S$-3 have good comprehensive properties with fire retardancy 3.2 mm UL94 V-0 level, LOI value 32.6%, tensile strength $247.3kg/cm^2$, surface roughness Ra $0.78{\mu}m$, showing a better application prospect. Through $IFRPC_S$-2(PP/MP-PER/EDAP) and $IFRPC_S$-3 a better flame retardancy than that of the $IFRPC_S$-1(PP/MP/EDAP) was investigated which was responsible for the formed more dense and compact char layer, improved synergy effect of MP and PER/DiPER.

• Journal of the Korean institute of surface engineering
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• v.50 no.6
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• pp.465-472
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• 2017

The ingot fabrication conditions related with the thermal shock bearing phase and microstructure have investigated for the rare earth zirconate ceramic material, lanthanum gadolinium zirconate, as a thermal barrier coating using electron beam evaporation method. The thermal shock resistance of the prepared ingot was evaluated by high energy electron beam irradiation. The rare earth zirconate ceramic powder was prepared by controlling the raw material powder composition of $La_2O_3$, $Gd_2O_3$ and $ZrO_2$ so as to have a composition of $(La_{0.3}Gd_{0.7})_2Zr_2O_7$ which was selected from the former study. Ingot samples were prepared under two conditions. The first condition is prepared by sintering the prepared powder mixture to form an ingot. The second condition is prepared by calcining the prepared powder mixture to form a composite phase and then sintering to form an ingot. X-ray diffraction(XRD) and Scanning Electron Microscope(SEM) were used to analyze phase forming behavior and microstructure of ingot samples. Nanoindentation method used to obtain elastic modulus and hardness of each ingot specimen. Also the stress distribution of ingot was simulated by using FEM method assuming the ingot surface was exposed to electron beam. As a results, in the case of an ingot having a network-shaped microstructure in which relatively coarse pores are included, it seems that the thermal shock resistance was higher than in the case of an ingot having a microstructure composed of relatively fine grains only or particles with the similar level size when the high energy electron beam irradiation.

• Journal of the Korean Society for Heat Treatment
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• v.31 no.3
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• pp.111-119
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• 2018

We report the post-annealing effect of Sn doped ZnO (ZnO:Sn) thin film grown on sapphire (001) substrate using radio-frequency powder sputtering method. During thermal annealing in a vacuum atmosphere, the ZnO:Sn thin film is transformed into a porous thin film. Based on X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analyses, a possible mechanism for the production of pores is presented. Sn atoms segregate to form clusters that act as catalysts to dissociate Zn-O bonds. The Zn and O atoms subsequently vaporize, leading to the formation of pores in the ZnO:Sn thin film. We also found that Sn clusters were oxidized to form SnO or $SnO_2$ phases.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.626-631
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• 1997

AlSiCa powders were prepared from the domestic Hadong Kaolin ($Al_2O_3{\cdot}2SiO_2{\cdot}2H_2O$). As a result of the reaction of Hadong Kaolin and carbon powder at reducing atmosphere, $Al_2O_3{\cdot}SiC$ composite started to form at $1300^{\circ}C$ and completed at $1400^{\circ}C$. The optimum amount of carbon was 1:4 in mole ratio. It was found that only bright-green $\beta-SiC$ phase forms when the mixture was packed without carbon powder in alumina crucible.