• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2C
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• pp.99-108
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• 2006

In this study a series of bench scale test are conducted to increase the undrained shear strength of clayey soils using by Electro-kinetic injection stabilization method. The sodium silicate was injected in anode reservoir and its concentration was changed with 500, 1000, 1500, 2000, 2500mM for configuration of applicability of Electro-kinetic injection stabilization method. Also, the treatment time and electric gradient was changed to acquire the optical influence factors. For increasing the shear strength to maximum values, the calcium chloride and aluminium hydroxide, which concentration was changed with 50, 250, 500, 750, 1000mM, were added at anode reservoir for 5 days after the treatment of sodium silicate in 5 days as the 2nd additives. The test of results in determination of sodium silicate concentration show that the undrained shear strength at each point had a tendency to converge into a constant value when the concentration of sodium silicate came to 1000mM and above. The maximum shear strength increasement was 800% compared with initial value. After a series of test, the electric gradient and treatment time for application of electric fielld were 1V/cm and 6 days. In case of 2nd additives test, the concentration for maximum shear strength is 250mM in all additives and the effects of shear strength improvement was developed approximately 20~30% in comparison to addition of single injection material.

• Food Science and Preservation
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• v.17 no.1
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• pp.91-99
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• 2010

Extraction and bleaching of citric acid- and pepsin-soluble collagens (ASC and PSC, respectively) from shark (Isurus oxyrinchus) skin and muscle were investigated. The optimal sodium hydroxide concentration for extraction was 0.3 M and the optimal treatment time for removal of foreign material was 9 h. The optimal sodium hypochlorite level for bleaching of shark skin was 0.48% (w/v), and sodium hypochlorite was a better bleaching agent than acetone, hydrogen peroxide (10%, v/v), sodium sulfite (0.48%, w/v), sodium thiosulfate (0.48%, w/v), or sodium metabisulfite (0.48%, w/v). Optimal citric acid concentration and extraction time for ASC were 0.3 M and 72 h, respectively, whereas optimal conditions for extraction of PSC were treatment with 0.1 M citric acid containing 0.1% (w/v) pepsin for 24 h. Protein contents in ASSC (acid-soluble shark skin collagen), ASMC (acid-soluble shark meat collagen), PSSC (pepsin-soluble shark skin collagen), and PSMC (pepsin-soluble shark meat collagen) were 88.66%, 83.09%, 90.33%, and 84.81% (on a dry weight basis), respectively, similar to that of commercial marine collagen (88.86%). Net collagen contents of ASSC, ASMC, PSSC, and PSMC, calculated from hydroxyproline levels, were 70.31%, 25.70%, 83.09%, and 32.94%, respectively. The yields of freeze-dried ASSC, ASMC, PSSC,and PSMC were 57.22%, 53.85%, 23.28%, and 20.61%.

• Fashion & Textile Research Journal
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• v.7 no.4
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• pp.439-444
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• 2005

This article describes the change in the hand value of chitosan-crosslinked cotton fabrics. The chitosan-crosslinked cotton fabrics were manufactured by mercerizing process using epichlorohydrin(ECH), 2% aqueous acetic acid and 20% aqueous sodium hydroxide. It proposed that the crosslinking and mercerizing were performed with the mixture of four different molecular weight chitosan and ECH in a single step. Cotton fabrics were dipped in the mixed solution of chitosan and ECH, picked up by mangle roller, pre-dried at $130^{\circ}C$, mercerized and crosslinked in NaOH solution and finally washed and dried. Mechanical and physical properties of the chitosan crosslinked fabric were measured on concentration and molecular weight by Kawabata Evaluation System(KES) and other instruments. As the concentration of chitosan solution increased, LT, WT, B, 2HB were increased. WT, B, 2HB, MIU, SMD, $T_0$, $T_m$ were decreased when chitosan was depolymerized. On the other hand, RT was increased when chitosan was depolymerized.

• Textile Coloration and Finishing
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• v.13 no.1
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• pp.38-44
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• 2001

The adsorption ability of dyes on chitin, a natural polymer was investigated for decolorization of dye wastewater. Chitin was manufactured in lab by decalcification in dilute aqueous hydrochloric acid solution and deproteination in dilute aqueous sodium hydroxide solution with shrimp shells. Absorbance of residue solution of dyebaths after dye adsorptions of chtin were measured in varieties of dye concentration and dipping periods. Three kinds of Direct dyes -C.I. Direct Red 81 (red 81), C.I. Direct Brown l(brown 1) and C.I. Direct Green 26(green 26) - were used. Red 81 and brown 1 have smaller molecular weight than green 26. The results from experimentals were of]tamed as follows: 1) Adsorption of green 26 was improved in dyebath by addition of salt, but red 81 and brown 1 were not found any improvements. 2) Smaller size of chitin particles could be absorbed much more speedy. In this experiments, the smallest range of chitin particle size was $250\mu{m}$ and less. 3) The most efficient amount of chitin for 20m1 of dyebath was 0.2g, 4) Both of red 81 and brown 1 showed good and speedy adsorption abilities as dyestuffs of over 90 percent in just one minute in dyebath of 0.01% dye concentration. But green 26 was absorbed slowly because of its large molecular weight. It took 40minutes to absorb dyestuffs of over 90 percent in dyebath of 0.01% dye concentration.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.449-455
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• 2009

The antioxidant properties of water extracted polysaccharides (PW), 1%(w/v) NaOH extracted polysaccharides (PN1), and 5%(w/v) NaOH extracted polysaccharides (PN5) were assessed in this paper. PW showed good capability of scavenging $H_2O_2$, anti-lipid peroxidation, reduction power, and scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH). The maximum values were all observed at the dose of 1 mg/mL sample. As far as the antioxidant activities of PN1 were concerned, the capability of scavenging superoxide radical, chelating metal, and total antioxidation showed higher than those of PN5. When polysaccharide concentration was 1 mg/mL, the 3 index described above were attached 71.8%, 51.6%, and $446.3{\mu}M$ Trolox equivalent, respectively. With respect to PN5, higher capabilities of scavenging hydroxyl free radicals were obtained while the peak of 84.8% was observed at the concentration of 1.0 mg/mL. Moreover, the concentration-dependent influences were characterized in all cases.

• Journal of the Korean Wood Science and Technology
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• v.47 no.1
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• pp.110-123
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• 2019

This work was conducted to examine the relationship between lignin content and the durability of larch (LAR) pellets. LAR sawdust was immersed in tap water (TW), sulfuric acid (AC) and sodium hydroxide (AK) solutions, and then the immersed sawdust was used for pellet fabrication. Klason lignin (KL) content of the immersed LAR, contents of soluble lignin (SL) and monomeric sugars liberated from the immersion of LAR, and durability of LAR pellets were measured. KL content decreased as the concentration of AC and AK solutions increased, but glucose content increased with increase in AC and AK concentration. Durability of wood pellets fabricated using non-immersed LAR sawdust was the highest, followed by those made using TW-, AK- and AC-immersed sawdust. LAR pellets became more durable as the concentration of KL and SL increased, but a significant positive correlation was found only between pellet durability and KL content. Through the fluorescent microscopic observation and SEM-EDX analysis, it was verified that lignin content of non-immersed LAR pellets was higher than that of AC- and AK-immersed LAR pellets. These results suggest that lignin might contribute to an increase in inter-particle bonding in wood pellets.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.7 s.144
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• pp.938-947
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• 2005

Kenaf basts were double retted by using water and enzyme. The best conditions were enzyme concentration $0.125\%$ and 1 day treatment at $50^{\circ}C$, 4 days treatment at $20^{\circ}C$. It was showed that the double rotting could be more economical and eco-friendly than just water rotting or enzyme rotting. Kenaf fibers have been cottonized by removing lignin and hemicellulose partially. In order to cottonize kenaf fiber, lignin of kenaf fibers were removed by sodium chlorite and then hemicellulose of kenaf fibers were removed by sodium hydroxide. The cottonizing phenomenon of kenaf fibers were was confirmed in transversal and longitudinal photograph of SEM. The tensile strength and crystallinity of cottonized fiber were investigated. The tensile strength and crystallinity were lower as the lignin and hemicellulose of kenaf fibers were less.

• Advances in concrete construction
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• v.8 no.3
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• pp.217-223
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• 2019

This paper presents the mechanical and microstructural properties of the geopolymer paste which was developed by utilizing the industrial by-products, rice husk ash (RHA) and ultra-fine slag. Ultra-fine slag particles with average particle size in the range of 4 to 5 microns. RHA is partially replaced with ultra-fine slag at different levels of 0 to 50%. Sodium silicate to sodium hydroxide ratio of 1.0 and alkaline liquid to binder (AL/B) ratio of 0.60 is taken. Setting time, compressive, flexural strengths were studied up to the age of 90 days with different concentrations of NaOH. The microstructure of the hybrid geopolymer paste was studied by performing the SEM, EDS, and XRD on the broken samples. RHA based geopolymer paste blended with ultrafine slag resulted in high compressive and flexural strengths and increased setting times of the paste. Strength increased with the increase in NaOH concentration at all ages. The ultra-small particles of the slag acted as a micro-filler into the paste and enhanced the properties by improving the CASH, NASH, and CSH. The maximum compressive strength of 70MPa was achieved at 30% slag content with 16M NaOH. The results of XRD, SEM, and EDS at 30% replacement of RHA with ultra-fine slag densified the paste microstructure.

• Structural Engineering and Mechanics
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• v.70 no.6
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• pp.671-681
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• 2019

This paper examines the applicability of artificial neural network (ANN) and multivariate adaptive regression splines (MARS) to predict the compressive strength of bacteria incorporated geopolymer concrete (GPC). The mix is composed of new bacterial strain, manufactured sand, ground granulated blast furnace slag, silica fume, metakaolin and fly ash. The concentration of sodium hydroxide (NaOH) is maintained at 8 Molar, sodium silicate ($Na_2SiO_3$) to NaOH weight ratio is 2.33 and the alkaline liquid to binder ratio of 0.35 and ambient curing temperature ($28^{\circ}C$) is maintained for all the mixtures. In ANN, back-propagation training technique was employed for updating the weights of each layer based on the error in the network output. Levenberg-Marquardt algorithm was used for feed-forward back-propagation. MARS model was developed by establishing a relationship between a set of predictors and dependent variables. MARS is based on a divide and conquers strategy partitioning the training data sets into separate regions; each gets its own regression line. Six models based on ANN and MARS were developed to predict the compressive strength of bacteria incorporated GPC for 1, 3, 7, 28, 56 and 90 days. About 70% of the total 84 data sets obtained from experiments were used for development of the models and remaining 30% data was utilized for testing. From the study, it is observed that the predicted values from the models are found to be in good agreement with the corresponding experimental values and the developed models are robust and reliable.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.421-426
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• 2001

The pneumatic classification and acidic leaching behaviors of phosphor sludge have been examined to establish the recycling system of rare earth components contained in waste fluorescent lamp. At first, separation characteristic of rare earth components and calcium phosphate in phosphor sludge was investigated by pneumatic classification. After pneumatic classification of phosphor sludge, rare earth components were leached in various acidic solutions and sodium hydroxide solution. For recovery of soluble component in leaching solution, rare earth components were separated as hydroxide and oxalate precipitations. The experimental results obtained are summarized as follows: (1) In classification process, rare earth components in phosphor sludge were concentrated to 29.3% from 13.3%, and its yield was 32.9%. (2) In leaching process, sulfuric acid solution was more effective one as a leaching solvent of rare earth component than other solutions. Y and Eu components in phosphor sludge were dissolved in sulfuric acid solution of 1.5 k㏖/㎥, and other rare earth components were rarely dissolved in leaching solution. Leaching degrees of Y and Eu were respectively 92% and 98% in the following optimum leaching conditions; sulfuric acid concentration is 1.5 k㏖/㎥ , leaching temperature 343 K, leaching time 3.6 ks and pulp concentration 30 kg/㎥. (3) Y and Eu components of phosphor sludge contained in waste fluorescent lamp were, effectively recovered by three processes of pneumatic classification, sulfuric acid leaching and oxalate precipitation methods. Their recovery was finally about 65 %, and its purity was 98.2%.