• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.87-94
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• 2021

While the shielding substances of radiation shields in medical institutions are beginning to be replaced by environmentally friendly materials, radiation protection according to the shielding properties of environmentally friendly substances is becoming an important factor rather than the existing lead shielding properties. Tungsten and barium sulfate are representative shielding materials similar to lead, and are made in sheets or fiber form with eco-friendly materials. Ytterbium is an impermeable material used as a fluorine compound in the dental radiation field. This study aims to evaluate the shielding performance in the x-ray shielding area by comparing the shielding properties of ytterbium by energy band and that of existing eco-friendly materials. When three types of shielding sheets were fabricated and tested under the same process conditions, the shielding performance of the medical radiation area was about 5 % difference from tungsten. Furthermore, shielding performance was superior to barium sulfate. In the cross-sectional structure of the shielding sheet, there was a disadvantage that the arrangement of particles was not uniform. Ytterbium oxide showed sufficient potential as a medical radiation shielding material, and it is thought that it can improve the shielding performance by controlling the particle arrangement structure and particle size.

• Advances in concrete construction
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• v.10 no.2
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• pp.93-104
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• 2020

Basalt fiber is an eco-friendly fiber and comparatively newer to the world of fiber-reinforced polymer (FRP) composites. A limited number of studies have been reported in the literature on the strengthening of reinforced concrete (RC) beams with basalt fiber reinforced polymer (BFRP). The present experimental work explores the feasibility of using the BFRP strips for shear strengthening of the RC beams. The strengthening schemes include full wrap and U-wrap. A simple mechanical anchorage scheme has been introduced to prevent the debonding of U-wrap as well as to utilize the full capacity of the BFRP composite. The effect of varying shear span-to-effective depth (a/d) ratio on the behavior of shear deficient RC beams strengthened with BFRP strips under different schemes is examined. The RC beams were tested under a four-point loading system. The study finds that the beams strengthened with and without BFRP strips fails in shear for a/d ratio 2.5 and the enhancement of the shear capacity of strengthened beams ranges from 5% to 20%. However, the strengthened beams fail in flexure, and the control beam fails in shear for a higher a/d ratio, i.e., 3.5. The experimental results of the present study have been compared with the analytical study and found that the latter gives conservative results.

• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.3
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• pp.171-177
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• 2019

Hay-making is one of the most common way for forage preservation in livestock industry. The quality and production of hay could be affected by various factors. This experiment was conducted to investigate the effect of tedding time and frequency on drying rate and feed value of forage rye (Secale cereale L.) hay. Rye was harvested on heading stage using mower conditioner. Hay was tedded at each set hour(09:00, 13:00 and 17:00) and sampled at each set hour to determine dry matter (DM) content. After two months' preservation, CP (crude protein), ADF (acid detergent fiber), NDF (neutral detergent fiber), IVDMD (in vitro dry matter digestibility), TDN (total digestible nutrient), RFV (relative feed value), DM loss, visual scores and total fungi count were determined for estimation of hay quality. Tedding was necessary for both speeding up drying rate and improving forage quality. Tedding at 17:00 showed lower NDF content (p<0.05), and also higher RFV value was found compared with tedding at 9:00 and 13:00 (p<0.05). On the other hand, it was observed that more DM losses would be found when tedding later (p<0.05). Tedding in 1~3 times per day were lower in ADF and NDF content (p<0.05), increased CP, TDN and RFV (p<0.05), got less DM loss (p<0.05), and contained less fungi during conservation compared with no tedding (p<0.05). On the other hand, tedding too frequent caused more DM loss (p<0.05). In conclusion, for shorter drying process and higher quality of forage rye hay, tedding at 13:00~17:00 for 1~2 times per day was recommended in this study.

• Advances in nano research
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• v.15 no.4
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• pp.315-328
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• 2023

The main goal of the present study was to assess the effects of eggshell powder (ESP) and halloysite nanotubes (HNTs) on the mechanical properties of abaca fiber (AF)-reinforced natural composites. For this purpose, a limited number of indentation tests were first performed on the AF/polypropylene (PP) composites for different HNT and ESP loadings (0 wt.% ~ 6 wt.%), load amplitudes (150, 200, and 250 N), and two types of indenters (Vickers or conical). The Young's modulus, hardness and plasticity index of each specimen were calculated using the indentation test results and Oliver-Pharr method. The accuracy of the experimental results was confirmed by comparing the values of the Young's modulus obtained from the indentation test with the results of the conventional tensile test. Then, a feed-forward shallow artificial neural network (ANN) with high efficiency was trained based on the obtained experimental data. The trained ANN could properly predict the variations of the mentioned mechanical properties of AF/PP composites incorporated with different HNT and ESP loadings. Furthermore, the trained ANN demonstrated that HNTs increase the elastic modulus and hardness of the composite, while the incorporation of ESP reduces these properties. For instance, the Young's modulus of composites incorporated with 3 wt.% of ESP decreased by 30.7% compared with the pure composite, while increasing the weight fraction of ESP up to 6% decreased the Young's modulus by 34.8%. Moreover, the trained ANN indicated that HNTs have a more significant effect on reducing the plasticity index than ESP.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.53-59
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• 2013

Since 1990s, the major recycling methods for mechanical recycling of FRP(Fiber Reinforced Plastics)boats has involved shredding and grinding of the scrap FRP in a new recycled product. But still it leads to secondary problem such as air pollution, unacceptable shredding noise level and few limited applications. This study is to propose a newly advanced method which is more efficient and environment friendly waste FRP regenerating system. As extracting FRP layer and making the recycled fiber for recycled-fiber reinforced concrete(RFRC) from waste FRP, the recycling process has some merits in a sense of the recycling energy and the environmental effects. In this study, for those tasks, spectro-chemical differentiation method and coloring water-soluble dye treatment makes the roving layer more distinguishable photophysically. Also that has remarkably reduced safety hazards and energy. Using the mechanical properties of polymers and composite, FRP with the orthotropic and laminated plastic structure has been easily separated in the new extracting system. Also the new method has introduced five kind of separating manuals for the some different compositions of FRP boats. The roving fiber of laminated glass-fiber layer is as good as the polyvinyl fiber which is cost-high commercial fiber to increasing strength of concrete products. The early study has shown the effectiveness of laminated glass-fiber layer which also is chemical-resistant due to the resin coating. These results imply that more efficient and environment friendly recycled glass fiber can be better applied to the fiber reinforced concrete(FRC) substitute and this study also has shown wide concrete applications with RFRC from the waste FRP boat.

• Textile Coloration and Finishing
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• v.33 no.1
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• pp.40-47
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• 2021

As modern society develops, it becomes very complex and diverse, and interests in the convenience of life and the natural environment are gradually increasing. Products used in our daily life are also changing according to the needs of consumers, and food packaging is one of them. In particular, retort packaging materials have been used for the purpose of long-term preservation of contents, but the appearance of products suitable for recent environmental issues has been somewhat delayed. Therefore, in order to develop eco-friendly and human-friendly products by replacing the metals used in the existing retort packaging materials, the possibility of substitution was examined using cellulose nanofibers, a natural material. As a result, it can be seen that all functions can be replaced according to the existing long-term storage characteristics for retort packaging films. In particular, not only oxygen permeability and water vapor permeability, which are one of the most important factors, but also heat resistance, which is heating durability, is evaluated as applicable to commercialization compared to products using metals currently in use.

• Journal of Fashion Business
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• v.26 no.3
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• pp.87-97
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• 2022

This study investigated the dyeability and color change of the natural dyes of SeaCell, a biodegradable functional fiber that is permanently added to cellulose fibers with natural additives extracted from seaweeds. The natural dyes used in the study are five dyes. Gardenia and turmeric, which are yellow-based natural dyes, Sappan wood and Lac, which are red-based natural dyes, and Indigo, a blue-based natural dye, were selected. The dyeability and color change according to the change of the mordant conditions and the number of times of dyeing were investigated. In addition, the dyeing properties and colors of cotton and silk fibers were compared under the same dyeing conditions as SeaCell. The study results are as follows. It was found that SeaCell had lower dyeing properties than silk, a protein fiber, in gardenia, sappan wood, and lac dyes, but had higher dyeing properties than cotton with the same cellulose component as SeaCell fibers. In the case of turmeric, it showed higher dyeing properties than cotton except for the no mordant condition. In the case of Indigo dye, SeaCell shows the best dyeability, indicating that it is a very suitable fiber for Indigo dyeing. As sustainable functional fibers are continuously developed in the future, natural dyes that are environmentally friendly and human-friendly are actively introduced and commercialized, and it is expected that they can be used as reference materials.

• Journal of the Korean GEO-environmental Society
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• v.15 no.4
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• pp.61-67
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• 2014

With a view to resolving environmental problems of hazardous cement, this study seeks to identify the unconfined compressive strength and bending strength of the vegetation block designed herein by utilizing high-strength natural soil stabilizer instead of cement. Soil stabilizer is mainly made of mixture of short fiber extracted from natural fiber and lime, etc. Soil stabilizer reinforces the shearing strength of soil to improve block supportive power and durability while preventing flood and frost damages. For the unconfined compressive strength test, test pieces were prepared by mixing soil stabilizer and weathered soil in different ratios of 6 %, 12 % and 18 %. Experiments were carried out according to curing periods of 5th, 7th, 14th and 28th of the day. For bending strength test, blocks were made in the same mixture ratios as for the unconfined compressive test and tested for each stage. Also, to evaluate for the field applicability, proposed optimum water content considering the characteristics of the soil stabilizer. Permeability test result for the vegetation block, satisfied by the KS F 4419 quality standards.

• The Research Journal of the Costume Culture
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• v.22 no.3
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• pp.431-439
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• 2014

This research verified the usefulness and practicality of citrus peel extract as a natural dye. This study dyed cotton, silk, and cotton/mulberry fiber blended fabrics using citrus peel extract, and measured the dyeability and functional property to verify their usefulness and practicality. The dyeing affinity of the citrus peel extract was measured by dyeing under alkaline conditions to determine the temperature and time for optimal dyeing conditions of the solution. The results show that a temperature and time of $60^{\circ}C$ and 30 minutes were optimal for dyeing cotton fabrics with citrus peel extract, $50^{\circ}C$ and 60 minutes for silk fabrics, and $60^{\circ}C$ and 60 minutes for cotton/mulberry fiber blended fabrics, respectively. In addition the results of measuring the color fastness of the cotton, silk, and cotton/mulberry fiber blended fabrics dyed with the citrus peel extract show that the color fastness was superior for washing, friction, sweat, and water. However, the color fastness for sunlight appeared to be slightly weak. In addition, it was found that fabric dyed with the citrus peel extract showed partial antimicrobial properties. The antimicrobial property appeared the greatest in the silk fabric. The cotton/mulberry fiber blended fabrics had 90% or more Staphylococcus aureus present, but the antimicrobial properties were not high in the cotton fabric. Additionally, the heavy metal content, which is harmful to the human body, appeared to be lower than standard figures, so the dye was found to be innocuous to humans. Therefore, when the results of this study are put together, citrus peel extract is sufficiently useful and practical as an ingredient for a natural dye. Moreover, there is ample possibility to develop citrus peel dyed fabrics as environmentally friendly fashion materials.

• Composites Research
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• v.33 no.4
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• pp.213-219
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• 2020

Recently, global facing environmental issues have been raised caused by plastic waste. Hence, increasing the demand for interest in environmentally friendly materials. In this row, research on engineering composite materials also replacing the synthetic reinforcement by introducing natural fibers. However, focus on the strength and interfacial adhesion between matrix and reinforcement is very essential in natural fiber composite, which is insufficient in the literature. There are number of approaches for improving the mechanical strength of the composites, one of the common methods is to reinforce additive nanoparticles. The present investigation, bio-additives were synthesized utilizing bio-waste, cheap, bio-degradable sea-weed powder that could replace expensive nanomaterials and reinforced into the CFRP composite through Hand lay-up followed by a vacuum process. Mechanical properties were evaluated and analyzed through microanalysis. The results concluded that synthesized additives are effective for improving mechanical properties such as tensile, flexural, impact, and shear strength. Overall, the results confirmed that the fabricated composites have potential applications in the field of engineering applications.