• Journal of Korea Foundry Society
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• v.18 no.4
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• pp.364-372
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• 1998

Effects of Si and Ca additions on the mechanical properties of AM60 based Mg alloys have been investigated. Hardness of the AM60 based Mg alloys reached a maximum value after aging for approximately 33 hours but the amount of hardness increase was negligible. The poor age hardening response of the alloys was due to low Al content, which implies that Al content must be >6 wt.% to observe age hardening effect. The tensile and yield strength increased with increasing Al, Si, and Ca content but elongation decreased with increasing Al and Si content. The best mechanical properties obtained in AM 40-2.5Si-0.2Ca alloy after T4 heat treatment were as follows; tensile strength 193.4 MPa, yield strength 79.2 MPa, and elongation 11.2%. High temperature property obtained from creep test was also improved by introducing $Mg_2Si$ which has high hardness, high melting temperature and low thermal expansion coefficient.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.180-180
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• 2010

The design and implementation of high rate deposition process and anti-scratch property of silicon oxide film by PECVD with UHF power were investigated according to the effect of UHF input power with HF bias. New regime of high rate deposition of SiOx films by hybrid plasma process was investigated. The dissociation of OMCTS (C8H24Si4O4) precursor was controlled by plasma processes. SiOx films were deposited on polyethylene terephthalate (PET) and polycarbonate substrate by plasma enhanced chemical vapor deposition (PECVD) using OMCTS with oxygen carrier gas. As the input energy increased, the deposition rate of SiOx film increased. The plasma diagnostics were performed by optical emission spectrometry. The deposition rate was characterized by alpha-step. The mechanical properties of the coatings were examined by nano-indenter and pencil hardness, respectively. The deposition rate of the SiOx films could be controlled by the appropriate intensity of excited neutrals, ionized atoms and UHF input power with HF bias at room temperature, as well as the dissociation of OMCTS.

• Journal of the Korea Fashion and Costume Design Association
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• v.8 no.1
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• pp.49-57
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• 2006

Turmeric is aromatic, perennial herb, up to 1m high and distributed in East Asia. Parts used of it Rhizomes and is known to be used a medicinal stuff yellow dye stuff from past to nowadays in the Oriental region. The objectives of this study were to investigate and to compare to the dyeability of Turmeric according to pH, temperature, mordants, and the antimicrobial properties of wool dyed with turmeric. The results of this study are as follows: The wavelengths of the strongest absorption of Turmeric extract were 420 nm respectively. The extracted dye from Turmeric has affinity to wool. The dyeing rates are decreased according to diluting times and the dyeing rates are increased according to high temperature. The color of pH 3-7 is yellow green, over pH 9 is turned to orange yellow. The color of the non-mordant sample is yellow but it changed to bright yellow by Al, to orange yellow by Cu mordant, and to brown yellow by Fe mordant. The launder fastness and is not good, 2-4 grade and the light fastness is bad, 2-3 grade, but the dry-cleaning fastness is generally good, 4-5 grade. The fabrics dyed with Turmeric extract showed high antibacterial property on Staphylococcus aureus.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.2
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• pp.67-71
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• 2017

At high temperature, the roles of $NH_4$ and $H_2O$ in $(NH_4)_2Fe(SO_4)_2{\cdot}6H_2O$ and $(NH_4)_2Zn(SO_4)_2{\cdot}6H_2O$ single crystals were investigated using a pulse NMR spectrometer. Temperature was shown to have a significant influence, causing changes in the deformation of $NH_4$ and $H_2O$. From the $^1H$ NMR and $^{14}N$ NMR spectrum, the forms of environment surrounding $^{14}N$ in $NH_4$ groups is more important than the loss of $H_2O$ groups. NMR studies indicate that $NH_4{^+}$ ions in Tutton salts play an important role in the changes of the crystal structure at high temperatures.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.621-626
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• 2022

Tungsten is a high melting point metal unlike other steel materials, and it is difficult to manufacture because of its high melting temperature. In this study, pressure sintering process method was applied to manufacture the tungsten materials at low temperature. Therefore, it is necessary to densify the sintered material by using a sintering additive. Studies have been conducted on how the amount of titanium for sintering tungsten affects the mechanical properties of tungsten in this study. In order to secure the densification mechanism of tungsten powder during the sintering process, the characteristics of the sintered tungsten material according to the change of titanium content were evaluated. It was investigated the relationship between sintering parameters and mechanical properties for densification of microstructures. The sintered tungsten materials according to sintering additive content showed high sintered density (about 16.31g/cm³) and flexural strength (about 584 MPa) when the content of sintering additive was 3 wt%. However, as the content of the sintering additive increases, mechanical property of flexural strength is decreased, and the porosity is increased due to the heterogeneous sintering around titanium.

• Korean Journal of Materials Research
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• v.25 no.9
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• pp.442-449
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• 2015

The effects of coating parameters were investigated in wear resistance coatings of Diamalloy-406 on Inconel 718 to obtain an optimum coating condition by high velocity oxy-fuel spraying. The coating parameters, the flow rates of source gases (hydrogen and oxygen), the powder feed rate, and the spray distance, were designed by the Taguchi method. The optimal conditions were determined: oxygen flow rate 34 FRM, hydrogen flow rate 57 FRM, powder feed rate 35 g/min, and spray distance 7 inch. Friction coefficients of the coating and the substrate decreased with an increasing sliding surface temperature from $25^{\circ}C$ to $450^{\circ}C$. The friction coefficient of Diamalloy-4006 coating decreased as the sliding surface temperature increased from $0.43{\pm}0.01$ at $25^{\circ}C$ to $0.29{\pm}0.01$ at $450^{\circ}C$. The wear trace and wear depth of the coating were smaller than the substrate at all temperatures tested. The relationship between spray parameters and wear resistance was discussed extensively, based on the measured roughness, hardness, and porosity in each coating.

• Fashion & Textile Research Journal
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• v.14 no.2
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• pp.320-330
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• 2012

The natural dyeing of cotton fabrics with guava leaf extract was investigated. The temperature and time of dyeing are $40^{\circ}C$ and $90^{\circ}C$ for eighty minutes, respectively. In addition, the dyebath has been set at pH 5. Sn pre-mordanted fabrics showed the highest K/S value. Regardless of dyeing temperature, K/S values were high when Al, Cu, Fe-mordanted fabrics were dyed in post-mordanting and Sn-mordanted fabrics were dyed in pre-mordanting. The K/S value of dyeing fabrics could be increased with repetitive dyeing and mordanting. Compared to untreated dyed fabrics, the K/ S values of fabrics which had been treated with soybean milk, chitosan and gall nut tannin were increased. The changed surface colors of fabrics that were treated with soybean milk, chitosan and gall nut tannin were Y, YR and achromatic colors. Fabrics dyed with alkaline water extract showed reddish color. Sn-mordanted fabrics dyed with acidic water extract showed vivid yellowish color, and Cu-mordanted fabrics dyed with ethanol extract showed yellowish green color. In case of Sn-mordanted fabrics, the washing fastness was level 4. The dry cleaning fastness also showed very excellent result with level 4-5. The rubbing fastness was better in dry rubbing than in wet rubbing of the fabrics. For the light fastness, all dyed fabrics showed low fastness. For antibacterial activity, the powder of guava leaf extract and the dyed fabrics with guava leaf extract showed 99.9% of high antibacterial activity. All dyed fabrics showed higher deodorization and UV protection rate than control fabric.

• Journal of Conservation Science
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• v.17 s.17
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• pp.19-32
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• 2005

The exterior of Korean traditional wooden buildings have been painted with Danchung of painting method using glue and pigments. However because of losing traditional techniques and materials through the period of colonization and industrialization, many problems are occurring today. Especially after several years from painting, occurrence of scalings and flakings in painting layer is a serious problem. To improve weathering resistance of painting layer caused by stress from the difference of swelling and shrinkage between painting layer and wood plate, was examined by weathering tests. The stress is due to the hydrophilic property of wood, mechanical properties(tensile property and stress relaxation) of painting layer, and priming methods by various binders such as glue, acrylic emulsion(Primal AC-3444), acrylic resin(Paraloid B-72). Because stress relaxation of acrylic emulsion of which glasf transition temperature is below room temperature$(7^{\circ}C)$ is high, painting layers with acrylic emulsion generate no scalings and flakings and are in the most durable state in all weathering tests. Priming method which starts from low concentration to high concentration, is more effective to improve durability than other priming methods.

• Elastomers and Composites
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• v.15 no.1
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• pp.3-9
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• 1980

The oxygen permeability and it's proofness of te various commercial polymer films have been investigated at the constant pressure and temperature. Oxygen proofness, the reciprocals of the oxygen permeability for the various samples, were determined by means of a coulometric oxygen permeability tester. The testing of sample films was performed at constant temperature $(23{\pm}1^{\circ}C)$ under 1 atm. for 24 hours. The order of the relative proofness observed are as follows; oriented Nylon (O. Nylon)> oriented Polyester (O. PET)>nonoriented Nylon (N. Nylon)>nonoriented Polyester (N.PET)> rigid Polyvinyl chloride (Rigid PVC)>semirigid Polyvinyl chloride (Semirigid PVC)> oriented Polypropylene (O. PP)>plasticized Polyvinyl chloride (P. PVC)> casted Polypropylene (C. PP)> low density Polyethylene (LDPE)>high density Polyethylene (HDPE, Inflation)> high density-polyethylene (HDPE, T-die) The oxygen proofness of the films was increased with the polarity cf polymer, the film thickness and mechanical orientation and decreased with the addition of plasticizer in PVC. For the use of wrapping materials, one film with the polar property in the main chain of the polymer molecule and the others with nonpolar property in it are laminated for the protection from oxygen and moisture.

• Composites Research
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• v.22 no.3
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• pp.35-43
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• 2009

In this study, for a radiator hose made of carbon black filled EPDM(ethylene-propylene diene monomer) rubber, a measuring method of crosslink density was established to analyze the aging behaviors under thermo-oxidative stresses. At $125^{\circ}C$, the crosslink density of the rubber specimens decreased slightly in the initial stage, but increased with increasing the aging time. Such variation in crosslink density was similar to that of tensile strength. This might be due to the formation of sulphoxide crosslinks as well as to additional crosslinks made by the reaction of unvalcunized sulfurs. A high temperature aging of rubber specimens at $180^{\circ}C$ caused a slight increase in crosslink density while it did a large decrease in tensile strength and elongation. With aging at high temperature, the formation of carbonyl groups in EPDM molecule chain and formation of sulphoxide crosslink, rather than the crosslink density variation itself, had a large influence on such changes in mechanical property.