• Advances in Energy Research
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• v.1 no.2
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• pp.147-163
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• 2013

The world faces several issues of energy crisis and environmental deterioration due to over-dependence on single source of which is fossil fuel. Though, fuel is needed as ingredients for industrial development and growth of any country, however the fossil fuel which is a major source of energy for this purpose has always been terrifying thus the need for alternative and renewable energy sources. The search for alternative energy sources resulted into the acceptance of a biofuel as a reliable alternative energy source. This work presents the study of optimization of process of transesterification of vegetable oil to biodiesel using NaOH as catalyst. A $2^4$ factorial design method was employed to investigate the influence of ratio of oil to methanol, temperature, NaOH concentration, and transesterification time on the yield of biodiesel from vegetable oil. Low and high levels of the key factors considered were 4:1 and 6:1 mole ratio, 30 and $60^{\circ}C$ temperatures, 0.5 and 1.0 wt% catalyst concentration, and 30 and 60 min reaction time. Results obtained revealed that oil to methanol molar ratio of 6:1, tranesetrification temperature of $60^{\circ}C$, catalyst concentration of 1.0wt % and reaction time of 30 min are the best operating conditions for the optimum yield of biofuel from vegetable oil, with optimum yield of 95.8%. Results obtained on the characterizzation of the produced biodiesel indicate that the specific gravity, cloud point, flash point, sulphur content, viscosity, diesel index, centane number, acid value, free glycerine, total glycerine and total recovery are 0.8899, 4, 13, 0.0087%, 4.83, 25, 54.6. 0.228mgKOH/g, 0.018, 0.23% and 96% respectively. Results also indicate that the qualities of the biodiesel tested for are in conformity with the set standard. A model equation was developed based on the results obtained using a statistical tool. Analysis of variance (ANOVA) of data shows that mole ratio of ground nut oil to methanol and transesterification time have the most pronounced effect on the biodiesel yield with contributions of 55.06% and 9.22% respectively. It can be inferred from the results various conducted that vegetable oil locally produced from groundnut oil can be utilized as a feedstock for biodiesel production.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.42 no.6
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• pp.800-804
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• 1997

To evaluate the characters related to rice grain quality as affected by silicate application, the ripened color, appearence and physicochemical properties of rice grain which were produced at the silt-loam paddy field of National Yeongnam Agricultural Exeperiment Station with a little poor drainage for trials on long-term effects of continuous application of same fertilizer were analyzed comparing with the NPK fertilizer an the NPK＋compost in 1995. The whiteness value and color space value in ripened color of rice hull by silicate application were higher than those in the plots of NPK and NPK＋compost, because of low percentage of rusty grain and sooty grain, The percentage of perfect grain in brown rice and in milled rice by the silicate application increased by 6.1~7.5% and by 1.8~3.5% respectively, as compared with the NPK application and white core and white belly of milled rice were decreased, The amylose content, protein content and starch-iodine blue value of milled rice by silicate application were lower than those in the plots of NPK and NPK＋compost, while the peak point and breakdown viscosity of gelatinized rice flour on amylograph, and tastes value evaluated as a indicater of pannel test by nireco tester were higher. By silicate application these factors could be affected toward better in eating quality.

• Journal of Microbiology and Biotechnology
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• v.26 no.6
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• pp.989-998
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• 2016

Acidic endo-polygalacturonases are the major part of pectinase preparations and extensively applied in the clarification of fruits juice, vegetables extracts, and wines. However, most of the reported fungal endo-polygalacturonases are active and stable under narrow pH range and low temperatures. In this study, an acidic endo-polygalacturonase (EPG4) was purified and characterized from a mutant strain of Penicillium oxalicum. The N-terminal amino acid sequence of EPG4 (ATTCTFSGSNGAASASKSQT) was different from those of reported endo-polygalacturonases. EPG4 displayed optimal pH and temperature at 5.0 and 60-70℃ towards polygalacturonic acid (PGA), respectively, and was notably stable at pH 2.2-7.0. When tested against pectins, EPG4 showed enzyme activity over a broad acidic pH range (>15.0% activity at pH 2.2-6.0 towards citrus pectin; and >26.6% activity at pH 2.2-7.0 towards apple pectin). The K_m and V_max values were determined as 1.27 mg/ml and 5,504.6 U/mg, respectively. The enzyme hydrolyzed PGA in endo-manner, releasing oligo-galacturonates from PGA, as determined by TLC. Addition of EPG4 (3.6 U/ml) significantly reduced the viscosity (by 42.4%) and increased the light transmittance (by 29.5%) of the papaya pulp, and increased the recovery (by 24.4%) of the papaya extraction. All of these properties make the enzyme a potential application in the beverage industry.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.90-95
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• 2014

Nylon66 extrudates as a function of the extrusion number were prepared by a twin screw extruder. Chemical structures, thermal properties, melt index, crystal structures, mechanical properties such as the tensile strength, elongation at break and impact strength, and rheological property were measured by FT-IR, $^1H$-NMR, melt indexer, DSC, TGA, XRD, universal tensile tester, Izod impact tester, and rheometer. FT-IR and $^1H$-NMR characterizations indicated that the number of extrusions did not affect the chemical structure. The decrease in the molecular weight was checked by the melt index of extrudates. There were no effects of the thermal history on the melting and degradation temperature. The tensile and impact strength and modulus were found to be similar, regardless of the number of extrusions, but the elongation decreased significantly. The complex viscosity of extrudates at low frequencies decreased with the extrusion number. No structural changes after extrusion were confirmed from the fact that there was no change in the slope and shape of G'-G" plot.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.184-189
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• 2008

Effects of sucrose at different concentrations (0, 10, 20, and 30%, w/w) on steady and dynamic shear rheological properties of sweet potato starch (SPS) paste (5%, w/w) were investigated. The steady shear rheological properties of SPS-sucrose composites were determined from rheological parameters based on power law and Casson flow models. At 25$^{\circ}C$ all the samples showed pseudoplastic and thixoropic behavior with high yield stress. Consistence index (K), apparent viscosity (${\eta}_{a,100}$), and yield stress (${\sigma}_{oc}$) values of SPS-sucrose composites decreased with increasing sucrose concentration from 10% to 30%. The decrease of swelling power was observed at higher sucrose concentration (>20%) and the low swelling power yielded a lower K, ${\eta}_{a,100}$, and ${\sigma}_{oc}$ values. In temperature range of 25-70$^{\circ}C$, Arrhenius equation adequately assessed variation with temperature. Oscillatory test data showed weak gel-like behavior. Magnitudes of storage (G') and loss (G") moduli increased with an increase in sucrose concentration and frequency. The SPS-sucrose composite at 30% concentration closely followed the Cox-Merz superposition rule.

• Composites Research
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• v.34 no.5
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• pp.290-295
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• 2021

The application of lightweight structural composites to automobiles as a solution in line with global fuel economy regulations to curb global warming is recognized as a megatrend. This study was conducted to provide a technical approach that can respond to the issue of replacing parts that require conductive properties to maximize the application of thermoplastic carbon fiber reinforced plastics (CFRPs), which are advantageous in terms of repair, disposal and recycling. By utilizing the properties of the low-viscosity polymerizable oligomer matrix, it was possible to prepare a thermoplastic CFRP exhibiting excellent impregnation properties while uniformly mixing the conductive filler. Various carbon-based conductive fillers such as carbon black, carbon nanotubes, graphene nanoplatelets, graphite, and pitch-based carbon fibers were filled up to the maximum content, and electrical and thermal conductive properties of the fabricated composites were compared and studied. It was confirmed that the maximum incorporation of filler was the most important factor to control the conductive properties of the composites rather than the type or shape of the conductive carbon filler. Experimental results were observed in which it might be advantageous to apply a one-dimensional conductive carbon filler to improve electrical conductivity, whereas it might be advantageous to apply a two-dimensional conductive carbon filler to improve thermal conductivity. The results of this study can provide potential insight into the optimization of structural design for controlling the conductive properties of thermoplastic CFRPs.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.10-21
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• 2021

Recently, the demand for atypical structures with functions and sculptural beauty is increasing in the construction industry. Existing mold-based structure production methods have many advantages, but building complex atypical structures represents limitations due to the cost and technical characteristics. Production methods using molding are suitable for mass production systems, but production cost, construction period, construction cost, and environmental pollution can occur in small quantity batch production. The recent trend in the construction industry calls for new construction methods of customized small quantity batch production methods that can produce various types of sophisticated structures. In addition to the economic effects of developing related technologies of 3D Concrete Printers (3DCP), it can enhance national image through the image of future technology, the international status of the construction civil engineering industry, self-reliance, and technology export. Until now, 3DCP technology has been carried out in producing and utilizing residential houses, structures, etc., on land or manufacturing on land and installing them underwater. The final purpose of this research project is to produce marine structures by directly printing various marine structures underwater with 3DCP equipment. Compared to current underwater structure construction techniques, constructing structures directly underwater using 3DCP equipment has the following advantages: 1) cost reduction effects: 2) reduction of construct time, 3) ease of manufacturing amorphous underwater structures, 4) disaster prevention effects. The core element technology of the 3DCP equipment is to extrude the transferred composite materials at a constant quantitative speed and control the printing flow of the materials smoothly while printing the output. In this study, the extruding module of the 3DCP equipment operates underwater while developing an extruding module that can control the printing flow of the material while extruding it at a constant quantitative speed and minimizing the external force that can occur during underwater printing. The research on the development of 3DCP equipment for printing concrete structures underwater and the preliminary experiment of printing concrete structures using high viscosity low-flow concrete composite materials is explained.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.276-286
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• 2021

General high fluidity concrete is the area of high strength concrete with a high amount of cement to secure the required fluidity and workability. Since most of the concrete structures currently used have normal strength, there is a limit to the practical expansion and practicality of use. Thus it is necessary to develop normal strength-high fluidity concrete with low binders that can be used not only in general buildings but also in special buildings, and can greatly reduce construction time and save labor costs. This requires to develop and apply the polycarboxylate-based superplasticizer. In this study, PCE was prepared for each combination of starting materials(WR, HB, RT) and the rheological properties of cement paste were analyzed using ringflow cone and a rotary viscometer. As a result, when PCE with a combination of WR 80%, HB 6.5%, and RT 13.5% was applied, the yield stress can be minimized while securing the plastic viscosity at level of the normal strength. In addition, high fluidity due to the high dispersion effect was confirmed.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1442-1455
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• 2018

The objective of this study was to examinate the differences of general component, chromaticity, pH, weight, loss on baking, specific volume bulk, diameter of upper side and height, mechanical texture, DPPH radical, ABTS radical, Total amount of phenol, Monacolin-K content, sensory test on Muffin using no Red Yeast Rice and different levels (2%, 4%, 6%, 8%, 10%) of Red Yeast Rice. pH was decreased as the amount of added Red Yeast Rice increased(control 8.35, RM2% 7.93, RM4% 7.86, RM6% 7.69, RM8% 7.49, RM10% 7.30). Weight and loss on baking were showed not too different depending the amount of added Red Yeast Rice, and the baking loss were at very low point. Adhesion, cohesiveness, elasticity, viscosity, and chewiness showed no attentive differences on mechanical texture analysis. As the level of Red Yeast Rice increased, DPPH radical, ABTS radical, and Total phenol content decreased. Monacolin K were at higher point as the level of Red Yeast Rice increased. The sensory test showed Taste, Texture, and Overall acceptability gained the highest point when using 4% of Red Yeast Rice. On the sensory test, 4% of Red Yeast Rice was considered to be the best level based on Flavor and Color. The results of these tests show 4% of Red Yeast Rice is most preferred and considered to be most suited with flour and rice flour.

• The Korean Journal of Food And Nutrition
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• v.32 no.4
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• pp.355-363
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• 2019

This study was conducted to explore the quality characteristics of colored rice depending on the cultivars (Jeogjinu, Josaengheugchal, Joeunheukmi, Heukjinjubyeo, Hongjinju, Heukjinmi, Geongganghongmi) for porridge. The moisture, crude protein, lipid, ash, amylose and damaged starch contents of colored rice ranged from 10.05~11.23%, 7.72~8.69%, 2.68~3.26%, 1.62~1.88%, 6.29~20.31% and 5.06~8.26%, respectively. The highest moisture (11.23%), crude protein (8.69%), lipid (3.26%) and ash (1.88%) contents of colored rice were detected in Heukjinjubyeo, Joeunheukmi, Josaengheugchal and Heukjinmi, respectively. The lowest amylose and damaged starch contents of colored rice were detected in Josaengheugchal and Joeunheukmi, respectively. In general, the water binding capacity, water solubility and swelling power of Heukjinmi were greater than those of the other cultivars. The investigation of the pasting properties (peak, trough, break down, final and setback viscosity, peak time, pasting temperature) of colored rice indicated a low value in Josaengheugchal. The lowest hardness (13,673.25 g) of colored rice was observed in Heukjinjubyeo while the highest digestibility (5.44 glucose mg/g) of colored rice was observed in Josaengheugchal. These results indicated that Josaengheugchal are suitable cultivars for porridge.