• Advances in concrete construction
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• v.13 no.2
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• pp.133-152
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• 2022

Ecological issues such as natural resource reduction and enormous waste disposals are increasingly leading in developing civilization toward sustainable construction. The two primary environmental issues are the depletion of natural resources and the disposal of trash in open landfills. Waste steel fiber (WSF) was investigated for usage as a cement-based concrete (CBC) constituent in this research. Recycling waste fibers both makes cement composites more long and cost-effective, also aids in pollution reduction. The objective of this study is to analyze the impacts of waste fiber on the fresh and mechanical features of concrete using recycled additives. A comparative research on the durability and mechanical qualities of fiber-reinforced concrete (FRC) constructed with natural aggregates was conducted for this aim. The obstacles to successful WSF recycling methods application in the building industry have been investigated, resulting that CBCs with these fibers make an economic and long lasting choice to deal with waste materials. The workability of fiber enhanced concrete was found to be comparable to that of normal concrete. Fibers have a considerable impact on the splitting tensile strength, flexural and compressive strength of recycled concrete. Fiber may enhance the water permeability. When the WSF content is 0.6 kg/m3, the water absorption is nearly half. Fibers would have no effect on its permeability.

• Journal of the Korean Society of Clothing and Textiles
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• v.48 no.3
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• pp.511-527
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• 2024

The aim of this study was to impart color to bacterial cellulose (BC) fabric using various natural plant-based dyes-namely, gardenia jasminoides, green tea, and pomegranate peel. A protein pretreatment was also applied to improve the BC fabric's dyeability and mechanical properties. The BC fabric's dyeing and mordanting conditions when using plant-based natural dyes were determined by changes in the K/S values. The dyeability of BC samples dyed with green tea or pomegranate peel improved when they were pretreated with soy protein isolate (SPI) prior to dyeing. Moreover, the SPI pretreatment was efficient in improving the BC fabric's tensile strength and flexibility. This study proposes a method for dyeing BC fabric that uses plant-based natural dyes and confirms the effects of the protein pretreatment on the fabric's dyeability and durability.

• Korean Journal of Materials Research
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• v.16 no.11
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• pp.692-697
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• 2006

Deodorization of natural zeolites have been improved not only for polar but also for non-polar pollutants by sucessive ion exchanges of H and Ag ions starting from Korean natural zeolite with high adsorption capacity. The modified zeolites with $TiO_2$ coating on the surface revealed high deodorization and photocatalytic decomposition effects. Further modification was made with $10{\sim}20nm$ silica nano particles coating on the surface, the resulting composite particles of $SiO_2/TiO_2/modified$ natural zeolite revealed not only comparable deodorization but also better durability and resisatnce to color change compared to the $TiO_2$/modified natural zeolite without much compensation of photocatalytic decomposition effect, when the composite particles were exposed to the polypropylene non-woven fiber coated with organic binder. It is expected for the composite particle prepared here to be used as indoor building materials for indoor air quality control.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.12-19
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• 2017

Yellow-hearted pine (YHP; Pinus densiflora for. erecta Uyeki) is one of the Red pine species and has extremely narrow growth ring and high ratio of heartwood growing in Korea. It has been used for valuable wooden constructions as palace and temple for royal family since the Joseon Dynasty period. However, scientific information on the wood properties of YHP is still very lacking. This study was carried out to investigate natural durability of YHP to fungi and termites attack. Examination of anti-fungal and anti-termite properties of YHP was performed at indoor condition using brown-rot fungi (Fomitopsis palustris), white-rot fungi (Trametes versicolor), and termite (Reticulitermes speratus). The results showed that weight loss of the heartwood in YHP after fungi and termite test was much lower than those of the sapwood in YHP. Furthermore, the highest mortality of termite was obtained from the heartwood of YHP. Consequently, it is clearly revealed that the heartwood of YHP has excellent durability against brown- and white-rot fungi and termite.

• Journal of the Korea Institute of Building Construction
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• v.20 no.2
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• pp.113-121
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• 2020

Lots of soil-pavement concrete placed showed a number of problems such as decreasing strength, and durability. In this research, to provide a solution of the problem reported the wasting materials of natural organic lime and magnesia lime were used as a hardener to achieve sufficient performance of soil-pavement concrete. Namely, as a stimulus of blast furnace slag, the natural organic lime and magnesia lime were tested within the mix proportion of 0 to 10 % for each lime to make a new hardener. As a result, in the case of mortar with 1 to 3 % of cement to fine aggregate, 30 % replaced blast furnace slag showed the more favorable results with 5 to 5 % of mix proportion for natural organic lime and magnesia lime.

• Advances in concrete construction
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• v.10 no.2
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• pp.171-183
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• 2020

The main objective of this study is the assessment of the ability of limestone mortars to resist to different chemical attacks. The ability of polypropylene (PP) fibres waste used as reinforcement of these concrete materials to enhance their durability is also studied. Crushed sand 0/2 mm which is a fine limestone residue obtained by the crushing of natural rocks in aggregates industry is used for the fabrication of the mortar. The fibres used, which are obtained from the waste of domestic plastic sweeps' fabrication, have a length of 20 mm and a diameter ranging between 0.38 and 0.51 mm. Two weight fibres contents are used, 0.5 and 1%. The durability tests carried out in this investigation included the water absorption by capillarity, the mass variation, the flexural and the compressive strengths of the mortar specimens immersed for 366 days in 5% sodium chloride, 5% magnesium sulphate and 5% sulphuric acid solutions. A mineralogical analysis by X-ray diffraction (XRD) and a visual inspection are used for a better examination of the quality of tested mortars and for better interpretation of their behaviour in different solutions. The results indicate that the reinforcement of limestone mortar by PP fibres waste is an excellent solution to improve its chemical resistance and durability. Moreover, the presence of PP fibres waste does not affect significantly the water absorption by capillarity of mortar nether its mass variation, when exposed to chloride and sulphate solutions. While in sulphuric acid, the mass loss is higher with the presence of PP fibres waste, especially after an exposure of 180 days. The results reveal that these fibres have a considerable effect of the flexural and the compressive behaviour of mortar especially in acid solution, where a reduction of strength loss is observed. The mineralogical analysis confirms the good behaviour of mortar immersed in sulphate and chloride solutions; and shows that more gypsum is formed in mortar exposed to acid environment causing its rapid degradation. The visual observation reveals that only samples exposed to acid attack during 366 days have showed a surface damage extending over a depth of approximately 300 ㎛.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.5
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• pp.205-211
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• 2015

Most of the sulfur is obtained from desulfurization of natural gas and crude oil. In Korea, more than 120 tons of sulfur are produced by refinery, and about 50 % of the produced sulfur is used as a raw material for the production of fertilizer and sulfuric acid. Modified sulfur is manufactured from excessive sulfur that could be used to improve concrete properties, and this study evaluated concrete strength and durability that contains modified sulfur. Flexural and compressive strengths of concrete with sulfur modified polymer were comparable to those of OPC concrete with mixing water at similar temperatures, while the strengths increased a little as mixing water temperature increased. It was also confirmed that the resistance to freeze-thaw damage was more dependent on entrained air characteristics obtained by a proper use of air entraining agent than on the use of sulfur modified polymer. When concrete was immersed in 5 % sulfuric acid, the rate of reduction in compressive strength of OPC concrete was less than 1/4 of the strength reduction of concrete with sulfur modified polymer. Also, the resistance of concrete with sulfur modified polymer to scaling due to the use of de-icing salt was evaluated as Class 1, while that of OPC concrete was evaluated as Class 4, as aggregates were exposed. Accordingly, it is believed that sulfur modified polymer could be effectively used for bridge deck concrete since sulfur modified polymer improves the durability of concrete.

• Journal of the Korean Institute of Gas
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• v.14 no.6
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• pp.15-20
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• 2010

Compressed Natural Gas (CNG) buses have been supplied since the year 2000 in order to resolve severe atmospheric pollution in metropolitan area and contributed on the improvement of urban atmospheric environment. However, it is indispensible to take an adequate measure to guarantee the safety of CNG vehicles because of the possibility of huge fire accident. A receptacle, connecting device between high pressure fuel supply tank and fuel line, plays an important role in CNG supply system. In recent, leakage of CNG from receptacles has been reported. So, the concern about the security and reliability of receptacles has been arisen. Therefore, a lot of efforts to prevent leakage are invested among researchers and the durability of this component should be guaranteed despite repeated operation. This research has performed durability tests of a CNG receptacle regarding the repeated usage, extreme chattering, and continuous full flow test. Although a receptacle used for CNG vehicle satisfies validation requirements in the test results, it has been found that failure in the function of leakage prevention in a receptacle could take place in the case of prolonged exposure to high supply pressure in common quick charging environment on site.

• Journal of the Korean Society of Costume
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• v.44
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• pp.181-199
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• 1999

The industry of modern clothing has deviated from the overflow of commercialism and the standardization and nowadays is going toward pursuing art, creativity, and high added value. This trend brings the return of the natural materials from the synthetic textiles and increases the value of old and handmade fabrics. Finally, the handmade-paper, which is a natural material, comes to be reconsidered as a new material for the clothing. Therefore, as the natural materials and the manufacture of handmade clothing are rising again, the qualitative improvement and globalization of clothing industry should be first realized through the developments of creative and various clothing materials and new expressing techniques. The above investigation and study have been synthesized and analyzed as follows: First, through the study on the origin of the paper clothing, its historical background and the process of its development, we've learned these two facts following : the paper clothing of the East in the past mostly had practiced meanings. On the other hand, in the West it had meanings which were raised the artist's emotions and beauty-consciousness to the artistic level by the various kinds of expressing methods. Second, handmade-paper was manufactured by the embedding method, which mixed mulberry pulp, gauze, corn, hair, sisal, silk and so on. It was found that handmade-paper had the affluent and proper texture as the clothing material and was be able to control the clarity through the variation of thickness. It was also confirmed that the creative and original texture with hand-worked molding beauty was obtained by the use of handmade-paper. Third, when the handmade-paper is used, the molding beauty of plane, relievo, and solid can be freely pursued, and various and effective molding conformation can be constructed by the effect of superposition and repetition. Also, because the maximum discretion from the various optional manufacturing methods is allowed, the molding beauty can be maximized when the clothes are manufactured with handmade-paper. Fourth, the gauze with strong drape was combined to overcome the stiffness and the tearing of the paper. As a result, the durability and the wearability of the paper were strengthened and thus the thus the applications as the clothing material were enlarged. In conclusion, in order to enhance the value, creativity, practicality, and artistic sense of the design for modern clothing, the clothes made of handmade-paper should be more studied. Moreover, for the generalization of paper clothes, the studies on the development of practical paper with paper with water resistance, post-treatment after dyeing, flexibility, and durability should be done. I really hope that this study will be the motive to provoke the possibility of handmade-paper as new clothing material in not only practical sense but also artistic sense.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1970-1971
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• 2007

The efficiency of such work highly depend on the worker's safety, who is protected by tools such as gloves, sleeves, blankets and flexible coverings among other manufactured natural-rubber goods. Use, storage and maintenance of these tools guarantee the quality and durability of the material. However, it might be observed that good tools made of such material are disapproved of when received from manufacturers or when they are removed from the warehouse for replacement. This work shows the experimental results obtained from ageing at a temperature of $100^{\circ}C$ for 48, 70 and 312 h, although the application of AC electrical tension in samples and the measuring of current leakage are presented. The measurements in samples were carried out with samples prepared from the deformulated commercial materials and respectively reformulated into thin films. The obtained results showed the mechanisms of conduction of samples in low and high electric fields. It was also identified an electric tension transition showing that in low fields it prevails the Ohm's law conduction, and in high electric fields it prevails the conduction of space charge limited current (SCLC). These results can support the natural rubber formulation process having as their main objective the reducing of the mechanisms that occur under high conduction current in high electric fields, which leads the material to a dielectric breakdown. It is necessary to research this raw material from different internationally standard clones to characterize dielectric and electric properties for industrial applications. Moreover, this natural material has a low commercial price when compared to the synthetic ones.