• Composites Research
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• v.24 no.3
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• pp.1-5
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• 2011

Since the environmental problems and new stricter regulations are forcing the industries to introduce more ecological materials for their products, biodegradable materials have attracted increasing attention. Among these materials, Polylactic acid(PLA) is a promising candidate for its modulus, strength, chemical resistance. However, PLA could not be used for automobile industries for its low heat resistance and impact strength. In this study natural fibers were (jute fiber was) introduced as reinforcements in order to improve heat resistance and impact strength of PLA. Especially for improving the adhesion between PLA and jute, various surface treatments were tried. With each treatment, we verified that the impact strength of composite was improved. With annealing treatment, we found a remarkable increase of heat resistance of PLA composite.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.511-517
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• 2015

Sound absorption capability of the flame resistant treated sawdust-mandarin peel composite particleboard was were estimated by two microphone transfer function methods. The weight of flame resistant treated board slightly increased by the treatment. The treatment improved fire retardant performance by decreasing the charred area of flame resistant treated board. Sound absorption capabilities of flame resistant treated sawdust-mandarin peel composite particleboard, in the entire estimated frequency range of 500-6,400 Hz was slightly lower than those of the control specimen. Sound absorption capability of both the control and flame resistant treated sawdust-mandarin peel composite particleboards were higher than that of commercial gypsum boards, being widely used as a sound absorber for ceiling at the estimated frequency.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.411-419
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• 2022

This study conducted acute oral toxicity test and acute dermal toxicity test to evaluate the toxicity of lightweight and high-strength cement composite containing carbon nanotube. It was compared with the toxicity of ordinary concrete that did not contain carbon nanotube. Both lightweight and high-strength cement composite and ordinary concrete were categorized in GHS category 5 as a result of acute oral toxicity test. In addition, no toxic symproms were observed during the acute dermal toxicity test in all specimens, concluding that those were judged to correspond to GHS category 5/unclassified.

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.137-141
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• 2010

Generally, polymer materials are not air-permeable and hydrophilic. In addition, they do not possess anti-fungal property. Hydrophilicity, air-permeability, and anti-fungal properties of new composites consisting of polymer, ceramic nanoparticles, and silver ion were investigated by contact angle measurements, air permeation time, and cell culture. The hydrophilic, air-permeable, and anti-fungal composites can be used in health care industry.

• Korean Journal of Agricultural Science
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• v.47 no.1
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• pp.183-191
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• 2020

Lichens are composite organisms consisting of a symbiotic association of a fungus with a photosynthetic partner (the photobiont or phycobiont), usually either a green alga or cyanobacterium. According to more recent studies, the biological activities of lichens and lichen substances include an antibiotic activity, antitumor and antimutagenic activity against human immunodeficiency virus (HIV), allergenic activity, plant growth inhibitory activity, and enzyme inhibitory activity. This study screened lichen extracts with a potent in vitro antifungal activity against plant diseases caused by phytopathogenic fungi. The compounds were isolated from Stereocaulon alpinum and Sphaerophorus globosus, and their chemical structures were identified as methyl hematommate, methyl β-orsellinate, 5-hydroxyferulic acid, sphaerophorin, and 2-heptyl-4,6-dimethoxybenzoic acid by electron ionization mass spectrometry (EI-MS) and nuclear magnetic resonance (NMR) spectral analyses. In vitro disease control against Alternaria mali, Cochliobolus miyabeanus, Colletotrium gloeosporioides, and Verticillum dahliae was evaluated. And among the five compounds, only methyl hematommate was effective against A. mali, C. miyabeanus, and C. gloeosporioides. The compounds were isolated from these lichens, which have a similar biosynthetic pathway, respectively. This is the first report of these compounds being isolated from these lichens.

• Journal of Fashion Business
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• v.22 no.2
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• pp.107-117
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• 2018

Nettle fiber, a sustainable fiber, was applied to the fabrication of denim to identify changes in textile appearance and formation. For the weaving of nettle denim, nine specimens, distinguished by three kinds of composite use of nettle fiber and three stages of fabrication processes, were used. The kinetic characteristics of the nine specimens were measured by the KES-FB system, and the images of the specimens of finished denim textiles, captured with a CCD Camera, were analyzed. In terms of the extensibility (EM) of nettle denim, all specimens showed post-processing increase, thereby suggesting an easy transformation of the textile as a source material for denim fabric. The effects of washing on the woven formation of denim were also identified. The geometric roughness (SMD), the problematic property of bast-fiber-like nettle fiber, was found to be decreased by washing. In terms of the bending rigidity (B) of the textile, the post-processing shrinking percentage of elastic nettle denim was found to decrease; all specimens that underwent bio-washing only also manifested that post-processing elasticity increased. To improve the draping of nettle denim, a mixed spinning together with washing were found to be advantageous. In terms of the shear stiffness (G), which is closely associated with the appearance of clothes, the formation of textile was improved regardless of the types of processing, including bio-washing and bleach washing.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1297-1302
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• 2012

The interaction between carbon monoxide (CO) and a cobalt-salen complex (Co(salen)) was studied and applied to detect CO. The metal complex doped PEDOT:PSS film exhibited good sensitivity to CO and differentiate CO from other gases. The response of the composite to CO was reversible (RSD < 5%) change in resistance upon removal of CO gas from the test chamber. The effects of adding Co(salen) in the probe film on the response of the sensor were investigated using AFM, XPS, and FT-IR spectroscopy. The sensitivity of the sensor increased as the Co(salen) concentration enhanced as it increased from 0.0 to 1.5 wt. %, where the highest sensitivity ($%{\Delta}R/R_o$) of $-25.0{\pm}0.05%$ was achieved with 1.0 wt. % Co(salen). The sensor containing probe exhibited a linear response ($R^2$ = 0.983) in the range of 0.5 to 10.0% CO (v/v) $N_2$, and the detection limit was 1.74% CO (v/v) in $N_2$.

• Environmental Engineering Research
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• v.24 no.2
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• pp.354-361
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• 2019

Renewable energy from biomass and biodegradable wastes can significantly supplement the global energy demand if properly harnessed. Pyrolysis is the most profound modern technique that has proved effective and efficient in the energy conversion of biomass to yield various products like bio-oil, biochar, and syngas. This study focuses on optimization of slow pyrolysis of banana peels waste to yield banana peels vinegar, tar and biochar as bio-infrastructure products. Response surface methodology using central composite design was used to determine the optimum conditions for the banana wastes using a batch reactor pyrolysis system. Three factors namely heating temperature ($350-550^{\circ}C$), sample mass (200-800 g) and residence time (45-90 min) were varied with a total of 20 individual experiments. The optimal conditions for wood vinegar yield (48.01%) were $362.6^{\circ}C$, 989.9 g and 104.2 min for peels and biochar yield (30.10%) were $585.9^{\circ}C$, 989.9 g and 104.2 min. The slow pyrolysis showed significant energy conversion efficiencies of about 90% at p-value ${\leq}0.05$. These research findings are of primary importance to Uganda considering the abundant banana wastes amounting to 17.5 million tonnes generated annually, thus using them as pyrolysis feedstock can boost the country's energy status.

• Korean Journal of Plant Resources
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• v.35 no.6
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• pp.820-824
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• 2022

Ecologically sustainable means of development is the point to support environmental homeostasis. One of our roles is to find bio-degradable resources that can be substituted for petroleum-based products to effectively abide by the natural viability. To counter the issues of deforestation and preserve biodiversity, it is necessary to produce a non-wood crop that can fulfill the requirement for raw material from which several products can be produced. Kenaf (Hibiscus cannabinus), a member of the family Malvaceae, is showing sufficient potentiality along this road-map. Due to its rich fiber content, it has been used extensively in various fields for long, probably as early as 4,000 BC. At present, kenaf has been used as provider of paper, plastics, fiber glass, biofuel, activated carbon and epoxy composite. This obviously catch one's attention towards its capability to replace petroleum-based products as a whole. Moreover, the plant shows considerable relevance in decreasing pollutants by virtue of its enormous absorption capacity. These multiple applications of kenaf justify its credibility to be the best resource for the better world. The paper presents an overview on its numerous uses reported in the literature that we have investigated and its great potential as a valuable multipurpose crop.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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• pp.553-559
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• 2016

There has been increasing global interest in the environmental pollution problems produced by fossil fuel consumption and greenhouse gas emissions. In order to tackle these issues, new renewable energy such as solar, wind, bio gas, fuel cell and pressure retarded osmosis(PRO) have been developed extensively. Among these energy sources, PRO is one of the salinity gradient power generation methods. In PRO, energy is obtained by the osmotic pressure generated from the concentration difference between high and low concentration solutions separated by a semipermeable membrane. The development for high power density PRO membranes is imperative with the purpose of commercialization. This study investigates development of thin film composite PRO membrane and spiral wound module for high power density. Also, the influence of membrane backing layer on power density was identified, and the characteristic factors of PRO membranes was determined. Different backing layers were used to improve power density. As expected, the PRO membrane with more porous backing layer showed higher power density.