• Geomechanics and Engineering
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• v.30 no.5
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• pp.461-469
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• 2022

One of the most important factors that should be considered for using any ground improvement technique is the stability of stabilized soil and the durability of the provided solution for getting the required engineering properties. Generally, most of the earth structures that are constructed on clayey soils are exposing movements due to the long periods of drying or wetting cycles. Over time, environmental changes may result in swells or settlements for these structures. In order to mitigate this problem, this research has been performed on mixtures of high plasticity clay with traditional additives such as lime, cement and non-traditional additives such as polypropylene fiber. The purpose of the research is to assess the most appropriate ground improvement technique by using commercially available additives for resisting the developed desiccation cracks during the drying process and resisting the volume changes that may result during wet/dry cycles as an attempt to simulate the changes of environmental conditions. The results show that the fiber-reinforced samples have the lowest volumetric deformation in comparision with cement and lime stabilized samples, and the optimum fiber content is identified as 0.38%. In addition, the desiccation cracks were not visible on the samples' surface for both unreinforced and chemically stabilized samples. Regarding cracks resistance resulting from the desiccation process, it is observed, that the resistance is connected with the fiber content and increases with the increase of the fiber inclusion, and the optimum content is between 1% and 1.5%.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.6
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• pp.13-19
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• 2004

This study was performed to evaluate permeable properties of eco-concrete using soil, natural coarse aggregate, soil compound and polypropylene fiber. The fIexural strength, ultrasonic pulse velocity and dynamic modulus of elasticity were increased with increasing the content of coarse aggregate, soil compound and polypropylene fiber. The flexural strength, ultrasonic pulse velocity and dynamic modulus of elasticity were 259 MPa, 3,527 m/s and 275 ${\times}$ 102 MPa at the curing age of 28 days, respectively. The coefficient of permeability was decreased with increasing the content of coarse aggregate and soil compound, but it was increased with increasing the content of polypropylene fiber. Accordingly, this concrete can be used for farm road.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.28-29
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• 2016

Recently, the attention on high tensile, and high performance cementitious composite (HPFRCC) which can minimize the damage from explosion of inflammable gas and chemicals has been increased. In spite of outstanding tensile performance, HPFRCC has the drawbacks of fiber ball, undesirable cost, and high autogenous shrinkage. therefore, in this research, to develop the optimum HPFRCC, the fundamental properties and autogenous shrinkage of HPFRCC was analyzed depending on various combination and content of organic and inorganic fibers.

• Fibers and Polymers
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• v.1 no.2
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• pp.83-91
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• 2000

Thermotropic liquid crystalline polymer made up of poly(p-hydroxybenzoate) (PHB)-poly(ethylene terephthalate)(PET) 8/2 copolyester, poly(ethylene 2,6-naphthalate) (PEN) and PET were mechanically blended to pursue the liquid crystalline phase of ternary blends. Complex viscosities of blends decreased with increasing temperature and PHB content. DSC thermal analysis indicated that glass transition temperature (Tg) and melting temperature (Tm) of blends increased with increasing PHB content. Both tensile strength and initial modulus increased with raising PHB content and take-up speed of monofilaments. In the WAXS diagram, only PEN crystal reflection at 2Θ=$15.5^{\circ}C$ appeared but PET crystal reflection was not shown in all compositions. The degree of transesterification and randomness of blends increased with blending time but sequential length of both PEN and PET segment decreased.

• Journal of the Korean Wood Science and Technology
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• v.29 no.3
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• pp.47-58
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• 2001

For finding both ways of recycling the wood and plastic wastes and solving the problem of free formaldehyde gas emission through manufacturing wood particle-polypropylene fiber composite board without addition of formaldehyde-based thermosetting resin adhesive, control particleboards and nonwoven web composite boards from wood particle and polypropylene fiber formulation of 50 : 50, 60 : 40, and 70 : 30 were manufactured at density levels of 0.5, 0.6, 0.7, and 0.8 g/$cm^3$, and were tested both in the physical and mechanical properties according to ASTM D 1037-93. In the physical properties, control particleboard had significantly higher moisture content than composite board. In composite board, moisture content decreased with the increase of target density only in the board with higher content of polypropylene fiber and also appeared to increase with the increase of wood particle content at a given target density. Control particleboard showed significantly greater water absorption than composite board and its water absorption decreased with the increase of target density. In composite board, water absorption decreased with the increase of target density at a given formulation but increased with the increase of wood particle content at a given target density. After 2 and 24 hours immersion, control particleboard was significantly higher in thickness swelling than composite board and its thickness swelling increased with the increase of target density. In composite board, thickness swelling did not vary significantly with the target density at a given formulation but its thickness swelling increased as wood particle content increased at a given target density. Static bending MOR and MOE under dry and wet conditions increased with the increase of target density at a given formulation of wood particle and polypropylene fiber. Especially, the MOR and MOE under wet condition were considerably larger in composite board than in control particleboard. In general, composite board showed superior bending strength properties to control particleboard, And the composite board made from wood particle and polypropylene fiber formulation of 50 : 50 at target density of 0.8 g/$cm^3$ exhibited the greatest bending strength properties. Though problems in uniform mixing and strong binding of wood particle with polypropylene fiber are unavoidable due to their extremely different shape and polarity, wood particle-polypropylene fiber composite boards with higher performance, as a potential substitute for the commercial particleboards, could be made just by controlling processing variables.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.3
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• pp.172-179
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• 2022

Sweet potato varieties with high fiber content in the storage root have poor texture when steamed or roasted. This study investigates the difference in fiber content among sweet potato varieties by soil and climate. The average fiber content of 'Hogammi', 'Sodammi', 'Pungwonmi', 'Danjami', and 'Jinyulmi' cultivars from the samples collected at farms in Haenam, Muan, and Unbong, Korea were 95.71, 66.73, 44.55, 40.55, and 38.53 mg/100g FW, respectively. There was no significant difference between site-specific conditions and varieties. Based on the degree of visual fibrousness, 'Hogammi' has an average of 3.6-4.0 with many thick stringy fibers. The fiber content of the 'Hogammi' cultivar was measured across 19 sites representing the main sweet potato growing regions of Korea. The fiber content was between 115.82 and 114.6 mg/100g in Haenam 2 and Boryeong 1, and 87.46 mg/100g in Hamyang. However, the fiber content at the remaining 16 sites was within the range of 94.63-108.52 mg/100g, although there were some site-level differences. The fiber content of the sweet potato storage roots were positively correlated with soil phosphorus (R² = 0.58^**), organic matter (R² = 0.52^*), and pH (R² = 0.51^*), which had a significance of 1% and 5%. The fiber content of sweet potato storage roots was found to have increased with increasing phosphorus content, organic matter and pH in the soil. However, there was no correlation with the amount of precipitation, days of precipitation and hours of sunshine with the fiber content of sweet potato at the selected sites.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.5 no.2
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• pp.137-146
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• 1995

Twenty(20) large commercial buildings located in Seoul with friable sprayed-on surface insulation material on ceilings were investigated for asbestos content in bulk material by polarized light microscopy and for airborne fiber concentrations in buildings by phase contrast microscopy. In addition, such building-related variables as building age, numbers of traffic, airflow, surface conditions of the ceiling, temperature, and humidity were studied for any correlation with airborne fiber concentrations. The results were as follows: 1. Chrysotile asbestos was found in two bulk samples with 3-5% content and with <1%in one sample out of total 20 bulk samples collected. Glass fiber and mineral wool were the two major constituents of the bulk samples. 2. The ceiling surfaces were very friable in 16 buildings and were relatively hard in 4 buildings. The friability of the surface material was dependent upon the type and the amount of binder that had been mixed with the sprayed-on surface material. 3. Airborne fiber concentrations were log-normally distributed and the geometric mean(geometric standard deviation) fiber concentrations in the underground parking lots, inside buildings, and outdoor ambient air were 0.0063(1.97)f/cc, 0.0068(2.29)f/cc, and 0.0033(2.36)f/cc, respectively. 4. No significant relationship of airborne fiber concentrations and all building-related variables studied except humidity was found. The results of this study suggest that the sprayed-on surface insulation material found in some commercial buildings may possibly be contaminated with asbestos. Since most of the ceiling surfaces surveyed were very friable and poorly maintained and the airborne fiber concentrations were relatively high, there is a possibility of asbestos fiber contamination in these buildings, particularly at those buildings with asbestos-contaminated surface material. Since poorly maintained surface conditions were thought to be a source of high airborne fiber concentrations, there is a urgent need of a systematic operation and maintenance program. Further study of non-occupational asbestos exposure in general population utilizing advanced analytical technique such as transmission electron microscopy is highly recommended.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.473-476
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• 2006

In this study, evaluation of fire-resistant performance for polypropylene fiber-mixed mortar was performed to establish specification for stability of tunnel structure against fire afterward. In the fire-resistant performance test with mix proportion of polypropylene fiber, cracks were observed for mortar under 0.15% of fiber content, but micro-cracks were remarkably reduced for mortar more than 0.2% of fiber content. From the results, we are concluded that optimal mix proportion of polypropylene fiber is $0.20{\sim}0.25%$.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.82-87
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• 1992

In this thesis, the fatigue tests were performed on a series of SFRC (steel fiber reinforced concrete)to investigate the flexural tensile behavior of SFRC varying with the steel fiber contents and the steel fiber aspect ratios. Beam specimens of 10$\times$10$\times$60cm are used. the specimen series are classified according to the steel fiber contents varying 0.5. 1.0, 1.5%, and to the steel fiber aspect ratios varying 60, 80, 100. The three point loading system was used in the fatigue tests. The minimum value of repeated loading was fixed at 10.0kgf and maximum value was 75% to static ultimate strength for periodically using concrete strain gages located at the lower end of the mid-span, and the stress-strain curves were drawn for each specimens, respectively. From the tests result, it was found that the larger steel fiber content and the smaller the steel fiber aspect ratio is , the tensile strain of SFRC under fatigue load proportionally increases. By the regression analysis on these results, the empirical formulae to predict the tensile strain of SFRC were suggested. In comparison of the tensile elastic modulus under fatigue load, it was also found that the larger steel fiber content and the smaller steel fiber aspect ratio is , the smaller decreasing rate of the stiffness of SFRC under fatigue load decreased.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.3
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• pp.262-265
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• 1993

Dietary fiber content and carbohydrate digestibility of dried soymilk residue (DSR) and tofu containing DSR were evaluated. Insoluble dietary fiber (IDF) content was 37.4 and 49.8% (%, moisture free basis) for common soymilk residue and DSR, respectively. Both soymilk residues contained 12.5% of soluble dietary fiber (SDF, dry basis). Tofu containing DSR, which is partially substituted with DSR corresponding to 10% weight of soybean used, had higher dietary fiber content (30% more for RDF and 45% more for SDF) than tofu manufactured in traditional manner. Carbohydrate digestibility was much lower in all tofu products ranging from 11% to 21%, and there was a negative correlation( r = -0.9243) between carbohydrate digestibility and total dietary fiber content.