• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.63-69
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• 2020

The volume of construction waste material from the entire waste material volume in Korea is approximately 47.3% to take the biggest ratio, and from them, the waste concrete takes up approximately 62.8% that recycling is an urgent issue to address. Therefore, the government recommends more diverse and broader facilitation of the recycled aggregate in order to promote recycling the construction waste materials. In addition, when using concrete recycled aggregate in building, building standard such as floor area ratio and building height are being mitigation. The standard is a condition that mitigation the floor area ratio by up to 15% when using up to 25% of concrete recycled aggregate. Therefore, this study reviewed the relaxation of construction of construction standards when using concrete recycled aggregate in order to actively recommend the use of concrete recycled aggregate. And using the recycled coarse aggregate among the recycled aggregate, the appropriate mixing time in the batch plant according to the substitution rate was derived. In addition, using recycled aggregate admixture in order to improve the drying shrinkage, did comparative analysis about physical and mechanical property of concrete.

• Resources Recycling
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• v.8 no.1
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• pp.23-28
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• 1999

Firing characteristics, transverse rupture strength, and heat capacity were studied of the heat-reservoir refractory materials made of red-firing clay, mill scale, and water glass. The firing shrinkage increased with increase of the clay proportion in samples. The volume of fired bodies showed shrinkage by drying up to $300^{\circ}C$, steady expansion in the 300-$700^{\circ}C$ range due to phase transition of iron oxides. and drastic expansion above $1200^{\circ}C$. Flexural strength decreased from 5.6 Mpa to 2.35 Mpa with the decrease of the ratio of clay to mill scale from 1:1 to 1:3 Heat capacities changed from 1.1 Joul/g$^{\circ}$C to 1.35 Joul/g$^{\circ}$C with the ratio of millscale to clay ratio from 1:1 to 1:3. Mill scale in the specimen appears to exist as liquid phase during firing. Firing the specimens in air leads to the eruption of the molten mill scale to the sample surfaces. Contrarily, firing samples in a refractory sagger with a cover suppressed the eruption of the molten mill scale to the surfaces. The addition of mill scale gave rise to porous sintered bodies which would delay cooling rates of heat-reservoir brick.

• Geomechanics and Engineering
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• v.22 no.3
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• pp.227-236
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• 2020

Expansive soils are renowned for their swelling-shrinkage property and these volumetric changes resultantly cause huge damage to civil infrastructures. Likewise, subgrades consisting of expansive soils instigate serviceability failures in pavements across various regions of Pakistan and worldwide. This study presents the use of polypropylene fibers to improve the engineering properties of a local swelling soil. The moisture-density relationship, unconfined compressive strength (UCS) and elastic modulus (E₅₀), California bearing ratio (CBR) and one-dimensional consolidation behavior of the soil treated with 0, 0.2, 0.4, 0.6 and 0.8% fibers have been investigated in this study. It is found that the maximum dry density of reinforced soil slightly decreased by 2.8% due to replacement of heavier soil particles by light-weight fibers and the optimum moisture content remained almost unaffected due to non-absorbent nature of the fibers. A significant improvement has been observed in UCS (an increase of 279%), E₅₀ (an increase of 113.6%) and CBR value (an increase of 94.4% under unsoaked and an increase of 55.6% under soaked conditions) of the soil reinforced with 0.4% fibers, thereby providing a better quality subgrade for the construction of pavements on such soils. Free swell and swell pressure of the soil also significantly reduced (94.4% and 87.9%, respectively) with the addition of 0.8% fibers and eventually converting the medium swelling soil to a low swelling class. Similarly, the compression and rebound indices also reduced by 69.9% and 88%, respectively with fiber inclusion of 0.8%. From the experimental evaluations, it emerges that polypropylene fiber has great potential as a low cost and sustainable stabilizing material for widespread swelling soils.

• Journal of the Korean GEO-environmental Society
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• v.10 no.4
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• pp.33-40
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• 2009

In earthwork projects, the designer considers cut and fill balance for minimizing earthwork which may significantly decrease construction costs. Despite carrying out considerable earthwork design, the decrease in volume of earth occurs in construction sites because of embankment settlement under self-weight, consolidation settlement of soft ground, cavity filling and soil loss due to rainfall-runoff. To reflect the decrease in volume of earth, the specifications for road construction just give shrinkage factors in embankment for soils without consideration of embankment settlement under self-weight. In this study, the computational method is used to estimate the amount of embankment settlement under self-weight developed by Iseda (1972) and Ishii (1976). This research shows that the total compression settlements are between 3 to 10 percent of embankment height according to the property of embankment material and embankment height. As a result, the designer should consider the compression settlement on embankment material under selt-weight.

• Journal of Sericultural and Entomological Science
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• v.18 no.1
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• pp.27-39
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• 1976

In this study several kinds of spun silk yarn-synthetic filament compounded yarn was manufactured, and several fabrics woven from above mentioned silk compound yarn for evaluation of serviceability as clothing materials. The following results were obtained: 1. Degumming agents are in the order of sodium silicate, sodium hydroxide, sodium carbornate, soap and water. 2. When the concentration of sodium hydroxide is exceeded 3%, degradation of floss silk property is resulted because of excessive dissolving out of silk protein. 3. Degumming effect is much improved by concentration of degumming agent and less by its treating time. 4. Simultaneous application of more the 2 kinds of degumming agent is desirable for improvement of floss silk. 5. Application of natural organic acid brings very good results in keeping original scooping and color of the silk. 6. Load and elongation it increased by compound with synthetic filament yarn. 7. Even the evenness of compound yarn is largely dependent on the quality of floss silk and extent of degumming, the C.V.% of silk compound yarn in the experiment was 8-12%. 8. Single bath dyeing technique was impossible for their cloth, and dyeing was performed in 2 bath system separately for silk and synthetic fiber. 9. Shrinkage ratio due to the dyeing of fabric was 23% in case of polyester and spun silk fabric. 10. The final woven cloth can be applicable to (a) Blouse in care of thin cloth (compound silk fabric) (b) Korean costume for women in case of thick cloth. (compound hand spun silk fabric)

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.519-524
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• 2017

Physical, mechanical and deteriorating properties of Phellodendron amure were investigated. Air dried density located indoor was 0.41 but $0.43g/cm^3$ outdoor. In oven dry shrinkage, T/R ratio for located indoor was 1.40 but 1.32 outdoor. Hygroscopic property at $40^{\circ}C$ with 90% relative humidity was 16.30% for indoor and 15.80% for outdoor. Compressive strength for outdoor conditioned sample was 43.81 MPa but 40.33 MPa for indoor conditioned. Also bending strenght for outdoor conditioned was 84.63 MPa but 68.80 MPa for indoor conditioned. Impact strength was 3.43 and $4.00J/cm^2$ indoor and outdoor, respectively. Hardness at cross-section was 47.92 and 49.20 MPa indoor and outdoor, respectively. With one-year conditioning at indoor or outdoor, there was no significantly different in strength properties, which came from strong resistance for deterioration. Also Phellodendron amure wood showed dimensionally stable raw material based on low T/R ratio.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.795-797
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• 1998

A $BaTiO_3$, ferroelectric material, was mixed $SrTiO_3$, $(x)BaTiO_3-(1-x)SrTiO_3$($0.7{\leq}x{\leq}1$) ceramic capacitor with stable electrical properties in high voltage was fabricated. And microstructure, electrical property were investigated with $SrTiO_3$ mol ratio. The shrinkage, open porosity, sintering density were predominated at $9BaTiO_3-0.1SrTiO_3$. Increasing $SrTiO_3$ mol ratio, curie temperature was shifted at low temperature and maximum permittivity was increased. Also, $0.9BaTiO_3-0.1SrTiO_3$ was showed stable dielectric properties at $25{\sim}80[^{\circ}C]$. V-I properties of specimen were observed in the temperature range of $21{\sim}143[^{\circ}C]$, were divided into three regions. The region I below 10[kV/cm] was shown Ohmic conduction, the region II from 10 to 30[kV/cm] was explained by the Poole-Frenkel emission theory and the region III above 30[kV/cm] was analysed by the tunneling effect.

• Elastomers and Composites
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• v.46 no.2
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• pp.112-117
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• 2011

Recently, high growth potential of barrier materials industry including high performance packing materials was expected with increasing the national income and well-being culture. As high barrier materials, polymer nanocomposites have considerable attractions due to their excellent physical properties compared to conventional composite materials. In general, polymer nanocomposites were consisted of polymer matrix and inorganic fillers, such as layered silicate, carbon nanotubes, and metal- or inorganic nanoparticles. Among these materials, layered silicate which was called as the clay was usually used as nano-fillers because of naturally abundant and most economical and structural properties. Clay-reinforced polymer nanocomposites have various advantages, such as high strength, flammability, gas barrier property, abrasion resistance, and low shrinkage and used for automotive and packing materials. Therefore, in this paper, we focused on the need of gas barrier materials and materials-related technologies.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.17-22
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• 2004

In this study, BNT($BaO-Nd_{2}O_3-TiO_2$) and $70P_{2}O_5-5B_{2}O_3-(25-x)BaO-xNa_{2}O$ glass-ceramic composites were fabricated and investigated in order to apply for low temperature cofired ceramic. The prepared BNT based glass-ceramic composites were sintered at $800{\sim}950^{\circ}C$ with the glass fit contents ranging from 10 to $15\;wt\%$. The properties such as sintering and dielectric property were investigated in the ceramic compositions according to the phosphate glass frit. The dielectric constant was varied between 10 to 40 and shrinkage rate was increased according to increasing glass frit.

• Journal of the Korea Institute of Building Construction
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• v.6 no.1 s.19
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• pp.101-107
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• 2006

While a Study with regard to the measurement on Concrete Strength and the Change of Drying Shrinkage in accordace with Content Ratio of Crushed Stone Powder, it is being analyzed as the result that the strength according to Content Ratio of crushed Stone Powder is somewhat lowering. Accordingly, it is the real situation that the Concrete mixed with Crushed Stone Powder is utilized for non-structural material, not for the structural material. Therefore, this Research willing to furnish the suitable utilizing scheme for construction site as well as practical life by means of conduct the experiment on both Concrete Pressure Strength according to mixture with Crushed Stone Powder and Elastic Modulus, it also presumes the optimum Elastic Modulus Equation after analysis of comparison with common concrete strength. As the result of the experiment, in case of the Content Ratio of Crushed Stone Powder is less than 5%, it did not display a big difference in its both strength and matter-property compare with common concrete. In case of Elastic Modulus, when the Pressure Strength is 50% and 40% respectively, the Elastic Modulus Equation accords very well with the provided condition of Quadratic function, and as the result of the Presumption on Elastic Modulus according to Content of Crushed Stone Powder, in case the Pressure Strength is 50%, Elastic Modulus Equation showed that Error Ratio of Cubic function is at degree of 0.0005%, in case the Pressure Strength is 40%, Elastic Modulus Equation was accorded well with the value of the experimental data likely as the Error Ratio of Cubic function is at the degree around 0.0034%, respectively.