• International Journal of Industrial Entomology and Biomaterials
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• v.44 no.1
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• pp.12-20
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• 2022

In this research, the silk web was hot-pressed for various times, the effect of press time on the structure and mechanical properties of silk non-woven fabric was also investigated. The yellowing appeared in the silk non-woven fabric and became more apparent as press time was increased. The crystallinity of silk was decreased by the hot press treatment and it did not change significantly with an increase of hot press time. The porosity of silk non-woven fabric was constantly decreased until 120 s and it did not change much after that. The thickness of silk non-woven fabric was significantly decreased by a press time of 10 s and slightly decreased with a further increase of hot press time. The hot press treatment increased the maximum stress and elongation of silk non-woven fabrics. The press time had a significant impact on the mechanical properties of silk non-woven fabric, with 90 s being the optimum condition for the best work of rupture of silk non-woven fabric.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.215-215
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• 2022

Starch synthase proteins (SSI, SSII and SSIII) in rice are mainly involved in amylopectin synthesis mediating its chain elongation, and the functional loss of SSII can increase amylose accumulation through decreasing of amylopectin chain proportions. For purposes of identifying functional haplotypes and evolutionary analyses of this gene, SSII-1, we investigated 374 rice accessions belonging to different subgroups of origins. We subsequently performed bioinformatic analyses on their variations through haplotyping, resequencing and structuring based on different classified populations. Haplotyping of cultivated rice accessions using genetic variations within SSII-1 genomic region of chromosome 10 revealed a total of 8 haplotypes, representing 6 functional haplotypes by 4 non-synonymous SNPs of three different exons (1, 4 and 10), which effect on protein structure. Higher nucleotide diversity value was found in wild group (0.0055) compared to any of cultivated subpopulations, of which aus showed the most reduction of diversity value (0.0003). Tajima's D analysis exhibits the most Tajima's D value only in admixture group (0.3600) which appears to be the cause of a sudden population contraction by rare alleles scarcity. A clear separation of some wild accessions from the admixed cultivated subpopulations was observed in PCA and phylogenetic analysis. Similar admixed pattern of population structure was estimated with an increased K values of 2 to 8 where genetic components of almost all cultivated subpopulations were shared with the wild which can also be subsequently estimated by very low F_ST-values by -0.011 (wild-aromatic) and -0.003 (wild-admixture).

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.147-153
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• 2019

The prestressing steel wire, which is applied a tension to reinforce the structure, is applied flexure simultaneously by the duct and the deviator. In order to evaluate the deflected tensile performance of the prestressing steel wire subjected to both tensile and flexural stresses, the numerical analysis for 600 cases with variables of wire diameters, mandrel diameters, and friction coefficient between mandrel and steel wire was performed. As the result of analysis, the larger the diameter of the steel wire was, the lower the deflected tensile performance was, and the effect decreased with the increase of the wire elongation. The effect of mandrel diameter and friction coefficient between mandrel and wire on the deflected tensile performance of the wire was very small. But the deflected tensile performance and the friction coefficient between mandrel and strand showed a relatively high correlation. Therefore, it is necessary to make enough large elongation to secure the deflected tensile performance. If there is a restriction on the elongation, it is necessary to reduce the diameter of the steel wire to an appropriate value, and to increase the friction between steel wires by adjusting the surface condition of the steel wire.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.141-148
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• 2000

As the steel plates used for automobile safety the TRIP-assisted multiphase steels are being introduced to automobile industry with respect to their remarkable mechanical properties for the combination of high strength and large elongation. This multiphase structure is generated by two stage heat treatment (intercritical annealing & isothermal treatment) The metastable retained austenite can be transformed to martensite when plastically deformed which results in TRIP effect. Actually the microstructure of TRIP-assisted steels consist of a fine dispersite. There present discussion deals with bainite reaction kinetics of austenite in the process o f two stage heat treatment. In relation to bainite transformation the characteristics of bainite reaction is found to be influenced by the bainite tempering temperature and also by the relative rate in which carbides precipitate within residual austenite.

• Textile Coloration and Finishing
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• v.20 no.2
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• pp.47-52
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• 2008

Nylon textured yarn is usually manufactured by disk type false twist texturing. Dyeing properties of nylon textured yam have not been studied yet. In this study, dyeing properties of nylon textured yam according to draw ratio out of process parameters were investigated. The fact that microstructure of nylon textured yarn in amorphous region particularly is transformed by draw ratio was confirmed indirectly by measurement of dyeing rate because dyeing rate was affected by the structure of amorphous region. Dyeing rate at draw ratio 1.29 was the lowest because the higher draw ratio increase amorphous orientation and disturb dye diffusion into amorphous region. The microstructure according draw ratio was indirectly confirmed by 5% strength, tenacity, elongation. But difference in K/S value and fastness was insignificant.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1182-1189
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• 2010

The mechanical behavior of a granular material is governed by the applying effective stresses and its skeletal structure which is considered to be the packing of particles giving overall density and degree of anisotropic. Factors that affect soil packing are the particle size, size distribution and shape, and the arrangement of grain contact. Soil particle size and shape are the most important factor, but difficult to quantify. In this study, 2D Fourier analysis is applied to quantify the shape of granular particles. Jumunjin sand was used in the experiment and particle images are captured using an optical microscope. The results showed that three lower order Fourier descriptor are closely related with roundness, sphericity of the granular particle. Also statistical approach is used to determine roundness, form factor, elongation ratio, roughness of Jumunjin sand.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.28-33
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• 2010

Ni alloy steel is able to use during long time because of good acid and corrosion resistance. So, it's research has focused on developing the alternative alloy which is economically feasible. Recently, consumption of Kovar steel is gradually increased in field of the jet engine and the gas turbine because of its low thermal expansive characteristics. The specimens of Kovar steel(29%Ni-17%Co) contain 0.00%C, 0.03%C, 0.06%C, 0.10%C and 0.20%C, respectively. Ingots are manufactured by VIM(vacuum induction melting furnace) and then specimens are made by automatic hot rolling after heat treatment. Strength of Kovar steel according to carbon contents is estimated by hardness, tensile and impact test. Hardness of the 0.20%C specimen is more improved approximately 14.4% than one of base metal. Its strength increases 32.4% of a base metal, and its impact energy is also enhance 11.5%.

• Journal of Korea Foundry Society
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• v.15 no.4
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• pp.351-359
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• 1995

The effects of In and Be additions on the aging behaviors and mechanical properties in the Al-Cu-Li alloy were investigated using the transmission electron microscope, the scanning electron microscope, hardness and tensile strength measurement. The aging is promoted and the double hardness peak is appeared by the addition of In and Be in the Al-Cu-Li alloy. The strength is increased, but the elongation and toughness are decreased by the addition of In in the Al-Cu-Li alloy. And the Al-Cu-Li-In-Be alloy has good combination with the strength, the elogation and toughness than Al-Cu-Li-In alloy.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.53-56
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• 2004

The mechanical properties and optical micrographs are studied for rolled magnesium alloy sheet with hexagonal close packed structure(HCP) at room and elevated temperatures. Tensile properties such as tensile strength, elongation, R-value and n-value are also measured for AZ31 magnesium alloy. Magnesium with strong texture of basal plane parallel to the rolling direction usually has high R-value and plastic anisotropy at room temperature. As temperature increases, the R-value for AZ31 magnesium sheet decreases. In addition, the AZ31 sheet becomes isotropy and recrystallization above $200^{\circ}C$. Formability of magnesium alloy sheets remarkably poor at room temperature is improved by increasing temperature. Sheet forming of magnesium alloy is practically possible only at high temperature range where plastic anisotropy disappears.

• Fibers and Polymers
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• v.5 no.1
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• pp.25-30
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• 2004

The present paper reports the impact of thermal treatment on the characteristics of core-sheath type hybrid technical yarns. The core-sheath type hybrid yams are prepared using DREF-III technology. Polyester and glass multifilaments are used as core components whereas the cotton and polyester staple fibers are the sheath components wrapped around the core filament with different proportions to form a hybrid structure. The thermal treatment is carried out both in dry and in wet state under relaxed condition and the thermal shrinkage, sheath-slipping resistance and tensile and bending properties of hybrid yarns have been studied. Thermal treatment markedly increases the thermal shrinkage and sheath-slipping resistance of hybrid yarns with polyester multifilament in core, but insignificant effect for yarns with glass multifilament in core. Breaking elongation of hybrid yams with polyester multifilament in core increases with treatment temperature. The hybrid yarns with glass multifilament in core are least affected by thermal treatment.