• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.2
• /
• pp.204-211
• /
• 2020

Poly-Lactic Acid(PLA) fiber is an eco-friendly material and is biodegradable, so it can be utilized for manufacturing porous construction materia ls with interna l pore connection. In this study, domestic PLA fiber products(0.5mm india meter, 1.0mm in length, 10mm in length) were tested for melting at high temperatures and high alkality, and they were incorporated with FA-based geopolymer. Compressive strength was obtained through high temperature curing and alkali activator, however the complete melting of the PLA fiber was not ensured. The previous study handling PLA fiber with 0.003mm in diameter was completely dissolved, but 0.5mm and 1.0mm in diameter showed 42.5% and 33.3% of dissolution ratio, respectively. In addition, the increasing fiber volume led floating fibers during curing, which had a negative effect on its workability and solubility. Although the properties of PLA fiber may vary depending on the raw materials and production conditions, PLA fiber with 0.1mm or less diameter is recommended for porous construction material.

• Korean journal of food and cookery science
• /
• v.33 no.2
• /
• pp.155-161
• /
• 2017

Purpose: The purpose of this study was to determine the quality characteristics of gluten-free frying pre-mix with insoluble dietary fiber powder (IDFP) from Chinese cabbage by-product. Methods: Frying powder mix was prepared with 0.5, 1.0, 1.5 or 2.0% IDFP. Fried powder mix only whit brown rice powder was used as a control. Spreadability, pick-up ratio and color of batter, texture, moisture and oil contents, oil absorption and sensory evaluation of fried sweet potato were determined. Results: L and a-values of batter decreased with increasing amount of IDFP, whereas b-value increased with IDFP addition. Hardness and crispiness of fried sweet potato increased with IDFP addition until 1.5%. Moisture content of fried sweet potato increased with higher IDFP addition whereas oil content and oil absorption decreased with increasing amount of IDFP. Sensory evaluation of fried sweet potato showed the best results in the 0.5% of IDFP addition group. Conclusion: Overall preference of IDFP samples was significantly higher than that of control. Based on the study, the optimal amount of IDFP for gluten-free fried powder mix was determined to be 0.5-1.5%.

• The Journal of Korean Society for School & Community Health Education
• /
• v.12 no.3
• /
• pp.43-64
• /
• 2011

Objectives: The purpose of this study was to provide the nutritional education data of the fruit and vegetable eating habits and dietary fiber intake of male and female high school students in the Daegu area. Methods: A survey was conducted on 300 male/female students from four general high schools in the City of Daegu, and the survey included questions ongeneral characteristics, dietary habits, eating behavior patterns and dietary intake. A 24-hour recall method was used for the dietary intake, and the surveyed dietary intake information was analyzed using the Computer Aided Nutritional analysis program (CAN 3.0)--dietary fiber intake, in particular. The data was analyzed using the SPSS window 12.0 program. Results: The average ages of boys and girls were 16.8- and 15.6-years old, respectively. A classification based on BMI showed the following: the low-weight student group was comprised of 10.3% boys and 31.6% girls; the normal-weight group 68.4% boys and 67.5% girls; and the overweight group 21.3% boys and 0.9% girls, whereby showing a significant difference between boys and girls. Vegetable intake showed the following: the ratio of the response of 'taking it once a day' was more than 70%, which showed the low frequency of fruit intake; the ratio of 'taking it more than five times a week' was 53.0% for boys and 68.4% for girls, which showed a higher intake frequency for girls over boys; and the daily dietary fiber per 1,000kcal was 7.1g for boys and 8.2g for girls, whereby showing a significant difference between boys and girls. The meals that contributed most to dietary fiber intake were the school meals, whereas the dietary fiber intake rate through breakfast was the lowest among the three daily meals. The food groups that contributed to dietary fiber intake were vegetable, grains and flavoring matters for boys and vegetable, grains and fruits for girls. Conclusions: In order to increase the daily dietary intake for growing adolescents, who are in an important stage for building the foundation of health, it's recommended that, in addition to the supplement for insufficient dietary fiber through a regular breakfast consisting of high dietary fiber content foods, nutrition-related education about the effects of dietary fiber on the human body be conducted.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.3
• /
• pp.93-102
• /
• 2016

The purpose of this paper is to investigate the flexural behavior of high-strength steel fiber-reinforced concrete beams with compressive strength of 130 MPa. The paper presents experimental research results of steel fiber-reinforced concrete beams with steel fiber content of 1.0% by volume and steel reinforcement ratio of less than 0.02. Both of normal-strength rebar and high-strength rebar were used in the test beams. Modeling as well as compressive and tensile strength test of high-strength steel fiber-reinforced concrete was performed to predict the bending strength of concrete beams. Tension modeling was performed by using inverse analysis in which load-crack mouth opening displacement relationship was considered. The experimental results show that high-strength steel fiber-reinforced concrete beams and the addition of high-strength rebar is in favor of cracking resistance and ductile behavior of beams. For beams reinforced with normal-strength rebar, the ratio of bending strength prediction to the test result ranged from 0.81 to 1.42, whereas for beams reinforced with high-strength rebar, the ratio of bending strength prediction to the test result ranged from 0.92 to 1.07. The comparison of bending strength from numerical analysis with the test results showed a reasonable agreement.

• Journal of the Korea Institute of Building Construction
• /
• v.12 no.4
• /
• pp.377-385
• /
• 2012

In this study, the Impact resistance of steel fiber and organic fiber reinforced concrete and mortar was evaluated and the improvement in toughness resulting from an increase in compressive strength and mixing fiber for impact resistance on performance was examined. The types of fiber were steel fiber, PP and PVA, and these were mixed in at 0.1, 0.5 and 1.0 vol.%, respectively. Impact resistance is evaluated with an apparatus for testing impact resistance performance by high-speed projectile crash by gas-pressure. For the experimental conditions, Specimen size was $100{\times}100{\times}20$, 30mm ($width{\times}height{\times}thickness$). Projectile diameter was 7 and 10 mm and impact speed is 350m/s. After impact test, destruction grade, penetration depth, spalling thickness and crater area were evaluated. Through this evaluation, it was found that as compressive strength is increased, penetration is suppressed. In addition, as the mixing ratio of fiber is increased, the spalling thickness and crater area are suppressed. Organic fibers have lower density than the steel fiber, and population number per unit area is bigger. As a result, the improvement of impact resistance is more significant thanks to dispersion and degraded attachment performance.

• Journal of the Korea Concrete Institute
• /
• v.28 no.4
• /
• pp.387-394
• /
• 2016

This study was evaluated that fundamental quality properties in the mortar level, as part of a basic study for development of fiber reinforced concrete using basalt fiber. Mortar mixtures used in the experiments used the mortar using cement only and high volume fly ash mortar using fly ash of 50%, was evaluated by comparison. As a experiments results, high volume fly ash mortar using 50% fly ash was effective for improving fiber dispersibility than mortar using cement only, accordingly, it showed that fiber aggregation phenomenon has been greatly reduced. In addition, if the fly ash used much more than 50%, the compressive strength has been shown to decrease of about 30%, fiber length and mixing ratio of basalt fiber was found to have a greater effect on flow properties than mechanical properties.

• Computers and Concrete
• /
• v.25 no.6
• /
• pp.509-516
• /
• 2020

Adding fibers improves concrete performance in respect of strength and plasticity. There are numerous fibers for use in concrete that have different mechanical properties, and their combination in concrete changes its behavior. So, to investigate the behavior of the fiber reinforced concrete, an in vitro study was conducted on concrete with different fiber compositions including different ratios of steel, polypropylene and glass fibers with the volume of 1%. Two forms of fibers including single-stranded and aggregated fibers have been used for testing, and the specimens were tested for compressive strength and dividable tensile strength (splitting tensile) to determine the optimal ratio of the composition of fibers in the concrete reinforced by hybrid fibers. The results show that the concrete with a composition of steel fibers has a better performance than other compounds. In addition, by adding glass and propylene fibers to the composition of steel fibers, the strength of the samples is reduced. Also, if using the combination of fibers is required, the use of a combination of glass fibers with steel fibers will provide a better compressive strength and tensile strength than the combination of steel fibers with propylene.

• Journal of Sensor Science and Technology
• /
• v.26 no.6
• /
• pp.414-419
• /
• 2017

The optical characteristics of cresol red, phenol red, and neutral red immobilized in the thin film were investigated with absorbance measurement in order to find a sensing part of a fiber-optic pH sensor. Sol-Gel method with tetramethyl orthosilicate as a precursor was used to immobilize the pH indicators in the thin film. The absorbance spectra were measured when pH indicators were immobilized in the film and were dissolved in the buffer solution. Experimental results showed that the absorbance spectra could be changed when the pH indicator is immobilized in the thin film. As compared with other pH indicators, the neutral red exhibited similar absorbance spectra regardless of physical conditions and was sensitive over whole pH range between 4 and 11. In addition, the absorbance ratio of base peak to acid peak tended to increase in proportion to the increase in pH. Experimental results indicate that the neutral red is a good pH indicator for fabrication of a sensing part of the fiber-optic pH sensor.

• Computers and Concrete
• /
• v.14 no.1
• /
• pp.1-18
• /
• 2014

The addition of steel fibers in concrete mixture is recognized as a non-conventional mass reinforcement scheme that improves the torsional, flexural, and shear behavior of structural members. However, the analysis of fiber reinforced concrete beams under combined torsion, bending, and shear is limited because of the complicated nature of the problem. Therefore, nonlinear 3D finite element analysis was conducted using the "ANSYS CivilFEM" program to investigate the behavior of fiber reinforced concrete L-beams. These beams were tested at different reinforcement schemes and loading conditions. The reinforcement case parameters were set as follows: reinforced with longitudinal reinforcement only and reinforced with steel bars and stirrups. All beams were tested under two different combined loading conditions, namely, torsion-to-shear ratio (T/V) = 545 mm (high eccentricity) and T/V = 145 mm (low eccentricity). Eight intermediate L-beams were constructed and tested in a laboratory under combined torsion, bending, and shear to validate the finite element model. Comparisons with the experimental data reveal that the program can accurately predict the behavior of L-beams under different reinforcement cases and combined loading ratios. The ANSYS model accurately predicted the loads and deformations for various types of reinforcements in L-beams and captured the concrete strains of these beams.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.254-255
• /
• 2017

The aim of this study is to investigate the impact resistant performance of steel short fiber-reinforced cement based composites (SFRCCs) containing 1.0, 1.5, 2.0 and 3.0% volume fraction of steel short fibers subjected to high velocity impact of steel projectile (the diameter of 19.05mm and the mass of 28.13g). The gunpowder impact facility was used for impact tests, and the impact velocity was from about 350 to 700m/s. The specimens were damaged in various failure modes, which are penetration, scabbing, and perforation. Comparing with Plain specimen, SFRCCs have superior capacity on the scabbing limit, and slightly bulged in the back side under the impact velocity of 700m/s. In addition, the impact resistant performance of SFRCCs improved with increase of steel short fiber volume ratio. The fibers play an important role in controlling the local damage of SFRCCs.