• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.95-105
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• 2014

Reinforced concrete (RC) shield tunnel lining must be designed for fireproof performance because the lining is sometimes exposed to very high temperature due to traffic accidents. Both experimental and numerical studies are carried out to evaluate fire resistance performance of precast RC tunnel lining systems. In the experimental studies, six full-scale precast RC tunnel segments are exposed to fire in order to examine the influence of various parameters on the fire resistance performance of precast RC tunnel lining. We used the temperature curve of the RABT criteria, which are severe conditions of fire temperatures. The fire test showed that the explosive spalling was not observed by substituting concrete to PP fiber reinforced concrete. A transient heat flow analysis was carried out in consideration of the material properties that change with temperature, and the results showed good agreement with the test results.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.6
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• pp.9-13
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• 2014

Glass fiber reinforced thermoplastics(GFRTP) is made by adding chemical additive to glass fabric which is strong at a high temperate, incorrodible, and good at intensity and specific gravity. Although we focused on the weight lightening, the intensity of GFRTP is also important. To remedy thermoplastic resin's inferior property of matter to thermo-hardening resin, we formed several specimen, differing the chemical additive as Homo PP, MAPP 3%, Rubber 5%, and mixed. We put pressure of 5 type on the specimens. The analyses result for the different pressure, the resin spreads evenly, then the coherence is increased. Eventually, the mechanical properties are changed. When high intensity is needed, it is good idea to use polypropylene(PP) which has good coherence with glass fabric as chemical additive. We can get better intensity when we form the resin at the optimum pressure depending on mixing of chemical additive and glass fabric than when we increase the pressure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.94-100
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• 2002

This paper is concerned with the development, and performance test of LIPCA (Lightweight Piezo-composite Curved Actuator) that is lighter than other conventional piezo-composite type actuators. LIPCA is composed of top fiber composite layers with a high modulus and low CTE (Coefficient of Thermal Expansion), a middle PZT cermaic wafer, and base layers with a high modulus and high CTE. The performance of each actuator was evaluated using an actuator test system consisting of an actuator supporting jig, a high voltage actuating power supplier, and a non-contact laser measuring system. The simply supported condition actuator was excited by the power supplier with 1.0Hz cycle and up to $100\sim400V_{pp}$. The displacement at the center point of actuator was measured with non-contact laser displacement measuring system, It has been shown that the LIPCA-C2 can 34% decrease in mass and 13% increase in displacement compared to THUNDER.

• Polymer(Korea)
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• v.31 no.3
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• pp.239-246
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• 2007

The sulfonated ion exchange fibers were synthesized by $Co^{60}\;{\gamma}-ray$ radiation-induced graft copolymerization. Degree of grafting was increased with increasing the total dose. The degree of grafting for POF-g-St/DVB copolymer was 1000%. The ion exchange capacity of sulfonated ion exchange fibers were increased by increasing the degree of sulfonation. Its maximum value was 5.06 meq/g. The ion exchange capacity of sulfonated POF- co-St/DVB ion exchange fiber was higher than that of the sulfonated POF- co-styrene ion exchange fibers. The amount of adsorption for heavy metals were also increased with increase in the degree of grafting of the ion exchange fibers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.111-118
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• 2019

This study examined the effect of amorphous metallic (AM) fibers on the spalling properties of ultra high strength concrete. Six specimens with concrete strengths of 100 MPa and 150 MPa were evaluated with mix proportions of polypropylene (PP) fibers of 0.15% by concrete volume, and proportions of AM fibers of 0.3% and 0.5% by concrete volume. These specimens were then heated in accordance with the ISO-834 heating curve. The movement of water vapor through a pore network formed by molten PP fibers was found to be a dominant factor controlling the spalling of high-strength concrete. Spalling control was not found to be significantly affected by the addition of 0.3% AM fibers; however, when 0.5% AM fibers was added, cracking was limited and so were paths for water vapor migration, increasing the likelihood of a moisture clog and creating the differential internal pressure often blamed for concrete spalling.

• Textile Coloration and Finishing
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• v.34 no.1
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• pp.20-26
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• 2022

Centrifugal spinning is an emerging technique for fabricating micro-to-nano-fibers in recent years. To obtain fibers with the desired size and morphology, it is necessary to configure and optimize the parameters used in centrifugal spinning. In this study, it was controlled by changing the solution's concentration (7.5, 10, and 12.5 wt.%) and disk's rotational velocity (6,000, 8,000, and 10,000 rpm) to prepare centrifugal spun nano-filter. The morphological property, air permeability, and dust collection efficiency of the PVA/PP bi-layer nanoweb prepared by centrifugal spun PVA on the PP micron nonwoven substrate are studied using a field emission scanning electron microscope, an air permeability tester, and a filter tester equipment, and the analysis results indicate that it is suitable as a nano-filter when the concentration of PVA solution is 10 wt.% and the rotational velocity of the disk is 8,000 rpm. The resultant reduced diameter and uniform fibers also proved that an excellent dust collection efficiency filter could be made.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.2
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• pp.143-152
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• 2006

High performance concrete(HPC) has been widely used in high-rise building. The HPC has several benefits including high strength, high fluidity and high durability. However, spalling is susceptible to occur in HPC and HPC also tends to be deteriorated in the side of fire resistance performance at fire. This paper investigated the spalling prevention of high performance RC column. Control concrete showed severe failure and a case of concrete with fire enduring spraying material exhibited more severe spalling failure than even control concrete. In addition, concrete with fire enduring paint reported the most favorable spalling resistance effect for preventing spall, compared with other concrete covered with finishing materials, such as fire enduring spraying material, gypsum board, marble board and fire enduring PC board. Meanwhile, concrete adding 0.1% of PP fiber demonstrated spalling resistance performance after 3hours load bearing test.

• Polymer(Korea)
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• v.27 no.6
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• pp.562-568
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• 2003

Environmental problems due to waste tire and waste plastics let us develop practical and economically feasible products. For this purpose, the characteristics of waste tire/plastic composites including various additives were examined using internal mixer. Experimental results indicated that the tensile strength and the flexural strength of waste tire/plastic composites decreased with the waste tire content. When 20 wt% of PP was added to the waste tire (60 wt%)/HDPE composites, the tensile strength was 1.5 times higher than the composite without PP, It was also found that the strain at break of composites increased by 2.5 times with 10 wt% addition of ethylene vinyl acetate and styrene ethylene butylenes styrene respectively. When 10 wt% of glass fiber was added to waste tire (60 wt%)/ HDPE composites, the tensile strength was 63% higher than the composite without glass fiber.

• Journal of Nutrition and Health
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• v.30 no.5
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• pp.465-477
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• 1997

The purpose of this article is to know the effects on bowel function of the kind of fiber and the amount of fiber in SD-rats. To do this experiment, we select of $\alpha$-cellulose as n insoluble cellulose source and alginic acid and pectin as soluble cellulose source. The rats diets contained callolose camcentrations of 1.0%, 3.6%, 6.0% and 10.0%. After that, we raised the SD-rats for 4weeks and measured the amount of food intake, body weight, the food effciency ratio, the length of liver and stomach the weight of the intestines, the transit time through the intestines, pH in feces, and the amount of bile acid and Ca, Mg, pp. 1) The amount of food intake was 15.75-31.00g/day. It was highest in the 10.0% cellulose group and the lowest in the 3.6% and 6.0% alginic acid group (p<0.05). The body weights of rats were 277.50-349.809. It was highest in the 1.0% pectin group and lowest in the 3.6% alginic acid group, 6.0% cellulose group, and 10.0% pectin group. It had differences according to the content fiber and the kind of dietary(p<0.01). The food efficiency ratio was (p<0.01). The higher the content of dietary fiber, the lower the calory and the food efficiency ratio. 2) Transit time was 446.0-775.0 minutes and it showed signidicant ifferences according to the content and kind of dietary fiber(p<0.01). It was long in the 1.0% cellulose group and 1.0% pectin group but short in the 10.0% alginic acid group. As the content of dietary fiber increased, the transit time through the intestines was shortened. The length of small intestine was 101.03-120.40cm and there were no difference cegardloss of the content and kind of fiber. The length of the large intestine was 20.92-25.42cm and there were significant differences according to the content and kind of the fiber. High-fiber diets resulted in increases in the length of the large intestine. 3) The weight of the liver was 8.68-10.96g and there were no differences according to the content and kind of fiber. The weight of stomach was 1.28-1.74g and there were no differences resulting from the kind of dietary fiber, but it was highest in the 10.0% alginic acid group. The weight of the small intestine was 5.52-8.04g with no difference resulting from to the kind of fiber. It was highest in the 10.0% the alginic acid group and lowest in the 1.0% alginic acid group(p<0.05). The weight of large intestine was 2.50-3.30g with no differences related to the kind of dietary fiber. It was heaviest in the 6.0% and 10.0% alginic acid groups and in the 10.0% pectin group with differences related to the content of fiber(p<0.05). 4) The pH of the feces was 5.82-6.86 according to the kind of dietary fiber, alginic acid group was high at 6.66, the cellulose group was 6.26. but the pectin group was low at 6.30. There were difference according to the content of fiber, but no consistency. The content of bile acid was 6.25-34.77umol per 1g of dry feces. According to the kind of dietary fiber, the alginic acid group was low at 12.91umol, cellulose group was 18.64umol and, the pectin group was the highest at 27.78umol(p<0.001). Based on the content of dietary fiber, alginic acid group was low at 1.0%, but high at 3.6% pectin group(p<0.001). 5) The amount of feces was 1.00-5.10g/day. The weight of rat feces was 2.23g/day in the alginic acid goup, 2.75g/day in the cellulose group, and 1.82g/day in the pectin group. According to the content of fiber, cellulose group was high at 10.0% but alginic acid group was 1.0%, and there were significant difference according to the dietary fiber. The more the content of fiber, the more increase the content of feces in alginic acid, cellulose and pectin group. The content of Ca in the feces was 80.10-207.82mg/1g of dry feces. In the dietary fiber, alginic acid group was 193.08mg, cellulose group was 87.5mg, pectin group was 138.16mg. In the content of fiber, alginic acid group was high at 1.0% and 3.6% but low at 10.0% of Pectin group. The content of Mg was 19.15-44.72mg/1g of dry feces. According to the kind of dietary fiber, alginic acid group was 35.33mg, cellulose group was 23.60mg, and pectin was 36.93mg. According to the content of fiber, pectin group was high at 1.0% and low at 10.0% of cellulose group. The content of P was 1.65-4.65mg/1g of dry feces. According to the kind of dietary fiber, alginic acid group 2.23mg/g dry feces, cellulose group was 2.29mg/g, pectin group wa 4.08mg/g dry feces. In the content of fiber, pectin group was high at 6.0% and low at 6.0% alginic acid group, but there were significant difference among the analysis value. The conetnt of Ca and MG was higher in soluble alginic acid group and pectin group than in insoluble cellulose group. The high the content of the dietary fiber, the lower the food efficiency ratio and the short the transit time through intestine with the increase of the length of large intestin as well as the higher level of the stomach, the small intestine and the large intestine. According to the content of the dietary fiber, the amount of the feces, Ca, Mg and P was increased but the length the small intestin, the weight of liver, pH of the feces and the amount of bile acid showed no differences and consistency.

• Elastomers and Composites
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• v.46 no.3
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• pp.211-217
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• 2011

Wood Polymer Composite (WPC) has attracted a great deal of attention in environmental industries due to renewable resources, processability, excellent physical properties and logging regulations for application to housing units and engineering construction materials. In this study, commercial WPCs were prepared by using a modular intermeshing co-rotating twin screw extruder. The effect of three main factors such as wood flour contents, coupling agent concentrations and pre-treatment of wood flour on the properties of WPCs was extensively investigated. It was found that tensile strength and thermal stability were decreased with increasing wood flour contents whereas the water absorption was increased. Addition of maleic anhydride grafted polypropylene (PP-g-MA) into WPC exhibited better physical properties. On the contrary, the water absorption was slightly decreased with PP-g-MA. Finally the sample, which was prepared with pre-treated wood flour, represented the highest tensile strength. However, the water absorption of the sample was increased due to the transition of crystalline structure of cellulose.