• Journal of Korean Association for Spatial Structures
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• v.15 no.2
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• pp.95-103
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• 2015

UHPC(Ultra High Performance Concrete) is used widely with its remarkable performance, such as strength, ductility and durability. Since the fibers in the UHPC can control the tensile crack, the punching shear capacity of UHPC is higher than that of the conventional concrete. In this paper, seven slabs with different thickness and fiber volume ratio were tested. The ultimate punching shear strength was increased with the fiber volume ratio up to 1%. The shear capacity of specimens with the fiber content 1% and 1.5% do not have big differences. The thicker slab has higher punching shear strength and lower deformation capacity. The critical sections of punching shear failure were similar regardless of the fiber volume ratio, but it were larger in thicker slab.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.6
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• pp.115-123
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• 2002

This study was performed to provide basic data for development and construction of reinforced soil wall that mixed with reinforcements such as calcium carbonate, monofilament fiber. In order to determine proper moisture content and mixing ratio by weight of reinforcement, Poisson's ratio and compressive strength tests for sandy soil had been conducted. Model tests for long-term behavior of reinforced soil wall were carried out to investigate the effect of reinforcement during loads and under static loads. The results of creep and model tests for sandy soil compared with clayey soil. Reinforced sandy soil mixed with calcium carbonate and cement showed brittle rupture by shear but that of mixed with monofilament fiber showed ductile rupture due to the tension force of fiber. It was shown that when age increased, creep strain of reinforced soil under sustained load approached constant values.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.415-423
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• 2004

To improve the brittle column behavior during seismic excitation, benefits of using steel fiber reinforced concrete in columns were investigated. For experimental study, eight specimens were used to evaluate the shear enhancement effect. The variables in this study were amount of shear reinforcement ratio (i.e., 0.26, 0.21 $\%$) and steel fiber volume fraction (i.e., 0.0, 1.0, 1.5, 2.0$\%$). The test results indicated that the maximum enhancement of shear capacity was shown in $1.5\%$ steel fiber content. In addition, to predict the maximum shear strength, equations of ACI 318-99, AIJ MB, NZS 3101, Hirosawa and Priestley were reviewed. From the parametric and regression study, modified Priestely equation was proposed by adding steel fiber effect.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.76-81
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• 2004

Injection molding is the most widely used process fir the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result. the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experientially. Using the image processing method, the fiber orientation distribution of welding pars in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.1
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• pp.73-80
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• 2005

Injection molding is the most widely used process for the industrial forming of plastic articles. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of welding parts in injection-molded products is assessed. And the effects of fiber content and injection mold shapes on the fiber orientation in case of fiber reinforced polymeric composites are studied experimentally.

• International Journal of Concrete Structures and Materials
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• v.2 no.1
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• pp.41-48
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• 2008

This study investigates the spalling properties of high strength concrete designed with various types of mineral admixture and diverse content ratios of polypropylene (PP) fiber. Experimental factors considered in series I are four pozzolan types of mineral admixture and series II consists of three shrinkage reducing types of mineral admixture. PP fiber was added 0.05, 0.10 and 0.15vol. % in each mixture of series I and series II, so that totally 27 specimens including control concretes in each series were prepared. Test results showed that the increase of fiber content decreased the slump flow of fresh concrete and increased or decreased the air content depending on the declining ratio of slump flow. For the properties of compressive strength, all specimens were indicated at around 50 MPa, which is high strength range; especially all specimens in series II were 60 MPa. Fire test was conducted in standard heating curve of ISO 834 with ${\phi}100{\times}200\;mm$ size of cylinder moulds for 1 hour. The specimens incorporating silica fume exhibited severe spalling and most specimens without the silica fume could be protected from the spalling occurrence in only 0.05vol % of PP fiber content. This fire test results demonstrated that the spalling occurrence in high strength concrete was not only affected by concrete strength related to the porosity of microstructure but also, even more influenced by micro pore structure induced by the mineral admixtures.

• Journal of Nutrition and Health
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• v.23 no.7
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• pp.492-503
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• 1990

This study was performed to investigate nutritional effect of various dietary fibers on lead absorption, and protein and lipid metabolisms in growing rats. Sixty male rats of Sprague-Dawley strain weighing 140$\pm$1.1g were blocked into 10 groups according to body weight and fed 10 kinds of diet different with fiber sources [non-fiber, cellulose, pectin, guar gum or carboxymethylcellulose(CMC)] and lead levels (0 or 1%) for 4 weeks. Results were summerized as follows : 1) Food intake, weight gain, FER and PER were remarkably decreased in lead(Pb)-added groups. Weight gain, FER and PER in Pb-added pectin group were significantly lower than those in Pb-added non-fiber group. 2) Liver and kidney weights, femur weight and length, hematocrit and hemoglobin content were decreased in Pb-added groups. Especially femur and liver weights in pectin groups were the lowest among groups. 3) Total protein content in serum was significantly decreased in Pb-added groups but was not different with dietary fiber sources. Total lipid content in serum was not different with dietary Pb levels and fiber sources, but cholesterol content in serum of guar gum group was significantly decreased by Pb addition. 4) Nitrogen, lipid and cholesteol contents in liver were significantly decreased in Pb-added groups, and lipid content in liver of pectin and CMC groups was lower than other groups. 5) Daily urinary and fecal excretions of nitrogen, kipid and cholesterol were decreased in Pb-added groups, and fecal nitrogen was significantly increased in Pb-added groups, and fecal nitrogen of cellulose and guar gum groups was significantly higher than other groups. Fecal excretions of lipid and cholesterol were increased by dietary fibers, and especially fecal lipid was remarkably increased in pectin and guar hum group. 6) Pb contents in liver and femur were decreased by dietary fibers. Especially Pb contents in liver, kidney and femur were significantly decreased in guar gum group. 7) Daily urinary and fecal excretions of Pb were significantly increased in cellulose and guar gum groups, and fecla excretion of Pb in guar gum group was twice of non-fiber group. Pb absorption ratio was significantly decreased in guar gum group. In conclusion, dietary fibers have effect on protein and lipid metabolisms, and decreased intestinal absorption of Pb by increasing fecal excretion. But the degree of effect was different with dietary fiber sources.

• Food Science of Animal Resources
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• v.32 no.6
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• pp.732-739
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• 2012

The aim of this study was to investigate the effect of chicken feet gelatin and wheat fiber levels on the quality characteristics properties of semi-dried chicken jerky. The obtained chicken feet gelatin swollen with hydrochloric solution (0.1 N HCl, pH $1.31{\pm}0.02$) was dehydrated via freeze-drying. Six formulations of chicken jerky that were prepared, based on the ratio of chicken meat, chicken feet gelatin and wheat fiber, were 100:0:0, 98:0:2, 99:1:0, 97:1:2, 98:2:0 and 96:2:2, respectively. The moisture content of semi-dried chicken jerky containing 2% wheat fiber was higher than that of jerky without the added fiber (p<0.05); moreover, an increase in the content of chicken feet gelatin also increased the moisture content. The drying yield of the samples increased with an increase in chicken feet gelatin. In addition, the drying yield of samples containing 2% wheat fiber was higher (p<0.05) than those without the added wheat fiber. However, the shear force of the samples significantly decreased with the increase in chicken feet gelatin content. Further, the shear force of the samples containing 2% wheat fiber was higher (p<0.05) than those without the added wheat fiber. No significant differences, except for color, were observed in the sensory analysis among the treatments.

• Advances in concrete construction
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• v.8 no.2
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• pp.139-144
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• 2019

In this study, the mechanical properties of reactive powder concrete (RPC) with a constant cement to silica fume ratio of 4 were investigated. In the experimental program, reactive powder concretes with steel fiber at different ratios were produced. Five productions using quartz sand with a maximum grain size of 0.6 mm were performed. A superplasticizer with a ratio of 3% of the cement was used for all productions. $40{\times}40{\times}160mm$ prismatic specimens were prepared and tested for flexural and compression. The specimens were exposed to two different curing conditions as autoclave and standard curing condition. Autoclave exposure was performed for 3 hours under a pressure of 2 MPa. It was observed that the compressive strength of concrete, along with the flexural strength exposed to autoclave was quite high compared to the strength of concretes subjected to standard curing. The results obtained indicated that the compressive strength, along with the flexural strength of autoclaved concrete increased as the amount of cement used increases. Approximately 15% increase in flexural strength was achieved with a 4% steel fiber addition. The maximum compressive strength that has been reached is over 210 MPa for reactive powder concrete for the same steel fiber ratio and with a cement content of $960kg/m^3$. The relationship between compressive strength and flexural strength of reactive powder concrete exposed to both curing conditions was also identified.

• Journal of Korean Association for Spatial Structures
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• v.23 no.2
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• pp.69-78
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• 2023

This paper investigates the effects of aspect ratio and volume fraction of hooked-end normal-strength steel fibers on the compressive and flexural properties of high-strength concrete with specified compressive strength of 60 MPa. Three types of hooked-end steel fibers with aspect ratios of 64, 67 and 80 were considered and three volume fractions of 0.25%, 0.50% and 0.75% for each steel fiber were respectively added into each high-strength concrete mixture. The test results indicated that the addition of normal-strength steel fibers is effective to improve compressive and flexural properties of high-strength concrete but fiber aspect ratio had little effect on the modulus of elasticity and compressive strength. As steel fiber content and aspect ratio increased, flexural beahvior of notched high-strength concrete beams was effectively improved.