• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.140-147
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• 1996

This study was performed to investigate the characteristics of workability and strength of the concrete containing admixtures such as silica fume, fly ash, blast furnace slag, and rice husk ash. For this purpose, the workability and the strength of the concrete containing each admixture were tested and analyzed according to the unit weight of binder and the replacement ratio of each admixture.

• Food Engineering Progress
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• v.23 no.2
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• pp.118-124
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• 2019

This study aims to investigate the physical properties of extruded psyllium husk upon the addition of emulsifiers. Three different emulsifiers-glycerol monostearate (GMS), polyglycerol ester (PGE), and sugar ester (SE)-were added to the mixture of psyllium husk and rice powder before extrusion. Extrusion was performed using a twin-screw extruder at 140℃ die temperature, 200 rpm screw speed, and 16% feed moisture content. The physical properties of psyllium husk extrudates including expansion ratio, specific length, piece density, texture profile, color properties, water soluble index, and water absorption index were evaluated. It was observed that the expansion ratio was the highest while the specific length and piece density were the lowest in the control which had no emulsifiers. Texture profile analysis showed that the apparent elastic modulus and breaking strength were highest in the extrudate with a PGE of 0.1%. The adhesiveness was found to be lowest in the extrudates with an SE of 0.1% and GMS of 0.5%. Lightness value was highest in the extrudate with a PGE of 0.1%. Color difference, water soluble index, and water absorption index were highest in the control. The results reveal that some physical properties of extruded psyllium husk were improved with the addition of emulsifiers. This finding provides useful information for the development of psyllium snacks with good physical characteristics.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.229-239
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• 2005

Dietary powder from Plantaginis ovatae testa was prepared by mechnical milling/grinding of the outer layer of the seed. The crystalline/surface structures of its powder (100 mesh) were examined, and several physical functionalities including, water capacity, oil holding capacity, emulsion/foam properties and physiological functionality such as in-vitro glucose and bile acid retarding effects were also investigated. Water holding capacity(WHC) of psyllium powder was $33.71{\pm}0.10g$ water retained/g solid at room temperature, whileas oil holding capacity(OHC) for soybean or rice bran oil were about 1.80g oil retained/g solid. These values of WHC and OHC were about 5.6 times higher and 2.8 times lower than those of commercial ${\alpha}$-cellulose, respectively. Changes of pH showed a small effect on WHC, but WHC increased with temperature. Emulsion capacity of 2%(w/v) psyllium was about 60% level of 0.5%(w/v) xanthan gum but emulsion stability after incubation of 24 hours showed about 1.4 times improvement of xanthan gum(0.5%,w/v). Also, psylliume(above 2%, w/v) alone had higher foam capacity than that of xanthan(1.1 times) and especially, 1 or 2% addition of psyllium improved the foam stability of protein solution(1% albumin+0.5% $CaCl_2$) by factor of 3.3 and 6.0 times, respectively. The glucose and bile acid retarding effects of psyllium powder were relatively very excellent suggesting the prevention from diabetes and arteriosclerosis. Especially, psyllium showed the 3.7 and 3.3 times higher effect on in-vitro glucose and bile acid retardation than those of commercial ${\alpha}$-cellulose, respectively.

• The Korean Journal of Mycology
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• v.33 no.2
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• pp.86-88
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• 2005

Antifungal activity of the extracts of plants and marine microalgae against Magnaporthe grisea was investigated. Acetone extracts of promegranate rind, leek seed, and maize husk demonstrated high antifungal activity against M. grisea. MIC (minimum inhibitory concentration) of acetone extracts of promegranate rind, leek seed, and maize husk was 100 ng/ml, $50\;{\mu}g/ml,\;and\;100\;{\mu}g/ml$ respectively. Ethanol extract of Amphiprora gigantea showed antifungal activity against M. grisea with MIC of $100\;{\mu}g/ml$.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.547-554
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• 2018

Torrefaction is the promising process of pretreating biomass materials to increase the quality of their energy, especially to upgrade the materials' grindability so that it is suitable for a commercial pulverizer machine. In this study, torrefaction of oak, bamboo, oil palm trunk, and rice husk was carried out under different torrefaction temperatures ($300^{\circ}C$, $330^{\circ}C$, and $350^{\circ}C$) and different torrefaction residence times (30, 45, and 60 minutes). Complete characterization of the torrefied biomass, including proximate analysis, calorific value, thermogravimetric analysis, mass yield, energy yield, and grindability properties (Hardgrove Grindability Index) was carried out. Increasing the torrefaction temperature and residence time significantly improved the calorific value, energy density (by reducing the product mass), and grindability of the product. Furthermore, for commercial purposes, the torrefaction conditions that produced the desired grindability properties of the torrefied product were $330^{\circ}C-30minutes$ and $300^{\circ}-45minutes$, and the latter condition produced a higher energy yield for bamboo, oil palm trunk, and rice husk; however, torrefaction of oak did not achieve the targeted grindability property values.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.62-71
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• 2017

This study was investigated on the properties of board made from carbonized rice husk differed in density of board, resin addition ratio and sawdust addition ratio. Water absorption is showed the lowest value to 80.09% when the resin addition ratio of 25%, as the density increased and sawdust addition ratio decreased, the water absorption was decreased. The measured thickness swelling satisfied with the quality standards of KS F 3104, so the feasibility of building interior has been confirmed in the dimensional stability. In case of resin addition ratio of 25%, the internal bond strength was satisfied quality standards of KS F 3104 to $0.244N/mm^2$. With increasing the density, resin and sawdust addition ratio, brinell hardness increased.

• Computers and Concrete
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• v.19 no.4
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• pp.435-442
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• 2017

In recent years, the use of supplementary cementing materials, especially in addition to concrete, has been the subject of many researches. Rice husk ash (RHA) is one of these materials that in this research, is added to the roller compacted concrete as one of the pozzolanic materials. This paper evaluates how different contents of RHA added to the roller compacted concrete pavement specimens, can influence on the strength and permeability. The results are compared to the control samples and determined optimal level of RHA replacement. As it was expected, RHA as supplementary cementitious materials, improved mechanical properties of roller compacted concrete pavement (RCCP). Also, the application of adaptive neuro-fuzzy inference system (ANFIS) in predicting the permeability and compressive strength is investigated. The obtained results shows that the predicted value by this model is in good agreement with the experimental, which shows the proposed ANFIS model is a useful, reliable, fast and cheap tool to predict the permeability and compressive strength. A mean relative error percentage (MRE %) less than 1.1% is obtained for the proposed ANFIS model. Also, the test results and performed modeling show that the optimal value for obtaining the maximum compressive strength and minimum permeability is offered by substituting 9% and 18% of the cement by RHA, respectively.

• Korean Journal of Materials Research
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• v.21 no.12
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• pp.685-689
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• 2011

The goal of this investigation was to produce a zirconia-family black ceramics that has enhanced functionality and reliability. Color zirconia ceramics have been produced by adding pigments. Pigments cause structural defects within zirconia and result in a drop in physical properties. Using environmentally friendly rice husk, we produced a black zirconia that is free of structural defects. In optimal firing conditions for black zirconia the calcining temperatures of the molding product are changed from $400^{\circ}C$ to $1200^{\circ}C$, and the firing temperatures are changed from $1400^{\circ}C$ to $1600^{\circ}C$. Color of testing the specimens was analyzed using Ultraviolet (UV) spectroscopy. Scanning Electron Microscope (SEM), EDAX (EDX), and Fourier transform infrared spectroscopy (FT-IR) analyses were carried out in order to examine impregnation properties and crystal phases. Universial Test Machine (UTM) was used to measure the flexual strength as well as the compressive strength. From experimental results, it was found that in optimal firing conditions the sample was calcined from $1000^{\circ}C$ to $1500^{\circ}C$. Commission internationalde I'Edairage (CIE) values of manufactured black zirconia color were $L^*$ = 29.73, $a^*$ = 0.23, $b^*$ = -2.68. The bending strength was 918 MPa and the compressive strength was 2676 MPa. These strength values are similar to typical strength values of zirconia, which confirms that carbon impregnation did not influence physical properties.

• Advances in concrete construction
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• v.11 no.1
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• pp.81-88
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• 2021

Rice Husk Ash (RHA) geopolymer paste activated by sodium aluminate were characterized by X-ray diffractogram (XRD), scanning electron microscope (SEM), energy dispersion X-Ray analysis (EDAX)and fourier transform infrared spectroscopy (FTIR). Five series of RHA geopolymer specimens were prepared by varying the Si/Al ratio as 1.5, 2.0, 2.5, 3.0 and 3.5. The paper focuses on the correlation of microstructure with hardened state parameters like bulk density, apparent porosity, sorptivity, water absorption and compressive strength. XRD analysis peaks indicates quartz, cristobalite and gibbsite for raw RHA and new peaks corresponding to Zeolite A in geopolymer specimens. In general, SEM micrographs show interconnected pores and loosely packed geopolymer matrix except for specimens made with Si/Al of 2.0 which exhibited comparatively better matrix. Incorporation of Al from sodium aluminate were confirmed with the stretching and bending vibration of Si-O-Si and O-Si-O observations from the FTIR analysis of geopolymer specimen. The dense microstructure of SA2.0 correlate into better performance in terms of 28 days maximum compressive strength of 16.96 MPa and minimum for porosity, absorption and sorptivity among the specimens. However, due to the higher water demand to make the paste workable, the value of porosity, absorption and sorptivity were reportedly higher as compared with other geopolymer systems. Correlation regression equations were proposed to validate the interrelation between physical parameters and mechanical strength. RHA geopolymer shows comparatively lower compressive strength as compared to Fly ash geopolymer.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.967-976
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• 2023

Biochar is emerging as a promising substance for achieving carbon neutrality and climate change mitigation. It can absorb several nutrients via ion bonding on its surface functional groups, resulting in slow dissociation of the bonds. Biochar, like organic fertilizers, contributes to sustainable nutrient management. The purpose of this study was to investigate the effects of nutrient-coated biochar amendments on leafy vegetables production and soil fertility. The nutrient-coated biochar was produced by soaking rice husk biochar in a nutrient solution containing nitrogen (N), phosphorus, and potassium for 24 hours. Nutrient-coated biochar and organic fertilizers were applied to soil at a rate of 120 kg·N·ha^-1. The growth components of the leafy vegetables showed that nutrient-coated biochar led to the highest fresh weight (FW) of both lettuce and kale (i.e., 146.67 and 93.54 g·plant^-1 FW, respectively). As a result, nutrient-coated biochar amendments led to superior yield compared to the control treatment and organic fertilization. The elemental composition of leafy vegetables revealed that soil amended with nutrient-coated biochar resulted in higher nutrient contents, which was attributed to the high nutrient contents supplied by the rice husk biochar. Soil amendment with nutrient-coated biochar positively enhanced the soil fertility compared to amendment with organic fertilizer. Therefore, nutrient-coated biochar is a promising substance for enhancing agronomic performance of leafy vegetables and improving soil fertility.