• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.199-205
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• 1990

With a view to improving the method of rice marketing quality estimation, vaietal milling characteristics and apparent qualities were studied and their statistical interrelationships were computed for 2 years crops, using 22 varieties of Japonica type and Japonica x Indica type (Tongil). The milling yield was the highest for Japonica, while the broken rice yields was the highest for Japa.xInd. type. But bran yield did not show any significant differences among rice types. Milling factors were volume weight of brown rice, dehulling yield, and Polishing yields; the better these factors, the higher the yield. High apparent quality milled rice with high milling yield were produced from rice types whose broken rice, chalked rice, husk yield and bran yield were little and/or low.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.21 no.5
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• pp.117-124
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• 2019

When manufacturing concrete, several mineral admixture is added to improve the basic physical property and durability and to make economical concrete. Such mineral admixture includes fly ash, granulated blast furnace slag, silica fume, etc., and not only the studies about mixing these mineral admixtures but also the studies for the development of new materials have been steadily in progress. Recently, some researchers have found, as a part of the development of new materials, the rice straw ash can also be used as a pozzolanic material for concrete considering similar chemical properties of rice straw ash to that of rice husk ash. But there has been insufficient amount of study about it. So, this study was to investigate the possibility as mineral admixture of agriculture by-product, by analyzing properties of concretes using rice straw ash with replacement ratio in comparison with other mineral admixture. In order to measure amount of SiO2 of rice straw ash, XRF(X-ray fluorescence) analysis was tested. For the measure pozzolanic reaction of rice straw ash, pH change and color change was tested according to curing day. Also to evaluate properties of concrete using rice straw ash, slump test, air contents test and compressive strength was tested.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.184-188
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• 1997

To investigate the absorption and transfer factor(TF) of Sr-85 by rice(Oryza sativa L.), experiments were carried out through pot cultivations on a sandy-loam soil treated 74 and 222Bq per gram of soil in a plastic film house. Sr-85 absorption rates of Ilpoombyeo, late maturing variety and Odaebyeo, early maturing variety, at harvesting stage, were 0.39-0.43% and 0.66-0.73%, respectively. Sr-85 absorption rates of Odaebyeo were about 1.5 times higher than those of Ilpoombyeo. Ratios of Sr-85 radiation and Sr-85 concentration in brown rice were much lower compared with those in straw and husk. Sr-85 concentrations in each part of Odaebyeo were remarkably higher than those of Ilpoombyeo. Transfer factor of Sr-85 from soil to plant ranged from 0.037 of brown rice to 4.13 of rice straw at harvesting stage. The order of the Sr-85 transfer factor in plant parts was straw>husk>brown rice. Sr-85 concentrations treated in soil had no effect on the growth and yield of rice.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.174-184
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• 2015

In the present study, the metabolism of [$^{14}C$]butachlor was investigated in rice plant according to the OECD test guideline No. 501. [$^{14}C$]Butachlor was treated as granule to paddy water by application of 1.5 kg ingredient (a.i.)/ha at the 3~4 leave stage of rice plant. At 85 days after treatment (DAT), samples of panicle, foliage, and roots were taken for radioactivity analysis. Upon harvest at 126 DAT, rice plants were separated into brown rice, husk, straw, and root parts. Amounts of total radioactivity absorbed by rice plant ranged from 8.6 to 9.8% of applied radioactivity (AR). Total radioactive residues (TRRs) of rice plant at 126 DAT was the highest as 4.0421 mg/kg (7.3% AR) in the straw followed by 1.4595 mg/kg (2.4% AR) in the root, 0.7257 mg/kg (0.1% AR) in the husk. The lowest level recording 0.1020 mg/kg (0.1% AR) was found in brown rice. Each part was extracted with various solvents and solvent/water mixtures. Greater than 70% of TRRs was readily extractable from foliage, panicle, husk and straw. Only 34.0% of the brown rice and 43% of root based on TRRs were extractable showing that the residues were completely assimilated in the plant tissue. The level of non-extractable radioactivity was ranged from 26.2 to 66.0% of TRRs. From this study, five tentative major metabolites (M1, M2, M3, M4 and M5) were observed in rice extracts. Among the metabolites, 2,6-diethylaniline assigned as M4 was identified in rice plant by comparing to retention time of reference standard. Un-metabolized butachlor was not detected in any fractions. In soil extracts, N-(butoxymethyl)-N-(2,6-diethyl phenyl)acetamide, 2,6-diethylaniline, M2, M3 and M5 were observed. And the concentration of butachlor was low level (ca. 0.03 mg/kg).

• Journal of the Korean Wood Science and Technology
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• v.34 no.5
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• pp.42-51
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• 2006

The this study, the effect of rice husk flour (RHF) as scavenger on formaldehyde emission rate and formaldehyde content from urea-formaldehyde (UF) resin bonded RHF content wood particleboards (PB). Two type of particle size ($30{\mu}m$ and $300{\mu}m$) of RHF was premixed with the UF resin at 5% and 15% by weight. The performance of UF resins is greatly influenced by the curing characteristics in their curing processing. The curing behavior was monitored activation energy ($E_a$) by DSC and pH variation according to RHF contents. PB with dimensions of $27cm{\times}27cm{\times}0.7cm$ was prepared at a specific gravity of 0.75 using $E_1$ and $E_2$ class UF resins. Formaldehyde emission and formaldehyde content from RHF filled PB bonded with UF resin was measured by 24 h desiccator and perforator method, respectively. RHF causes an increased pH of UF resin. $E_a$ of the modified UF resin decreased independently of RHF particle size. As the pH and the $E_a$ variation of the UF resin containing RHF increased, the amount of formaldehyde content decreased. The formaldehyde emission and formaldehyde content levels of the PB bonded with 15 wt% of $30{\mu}m$ RHF and $E_2$ type UF resin were low and satisfied grade $E_1$, as measured by 24 h desiccator and perforator method. The result of a comparison between 24 h desiccator and perforator test using PB showed that the linear regression analyses show a good correlation between the results for the 24 h desiccator and the perforator tests. The linear regression of a correlation between the desiccator and the perforator was Y=4.842X-0.064 ($R^2=0.989$). RHF was effective at reducing formaldehyde emission and formaldehyde content in urea-formaldehyde adhesives when used as scavenger.

• Research in Plant Disease
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• v.21 no.3
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• pp.215-221
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• 2015

This study was conducted to control ginger rhizome rot treated with the combined treatment, the hairy vetch, carbonized rice husk and eggshell calcium in organic ginger farm. Early symptoms of leaf yellowing and plant wilt began in the chemical fertilizer treatment on July 1. Ginger rhizome rot was more progressed on October 2, and stem browning and dead plant showed a high disease incidence with from 36.7% to 43.0%. On the other hand, the combined treatment did not occur at all until July 1 and delayed the disease incidence to October 2. It showed a low disease incidence of 1.3% to 1.7%. In the combined treatment, the content of soil Na, Fe, Cu was decreased and organic matter was increased twice with 31.6% than previous. Population density of Pythium sp. is lower in the combined treatment ($0.3-2.0{\times}10^3cfu/g$ than the chemical fertilizer treatments ($12.0-12.3{\times}10^3cfu/g$). The combined treatment, hairy vetch, carbonized rice husk and the eggshell calcium is able to control the ginger rhizome rot in organically cultivated ginger field.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.415-423
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• 2007

Pyrolysis characteristics of sawdust and rice husk as biomass resources in a thermogravimetric analysis were determined. Experiments were carried out with a linear heating rate under inert atmosphere of $N_2$ gas. Pyrolysis of the biomass can be classified as a lower temperature reaction zone where the major component of holocellulose is thermally decomposed and a high temperature reaction zone where lignin is thermally decomposed. The obtained data was analyzed by the two-step consecutive reaction model. Activation energies of sawdust and rice husk are found to be respectively 82.5 kJ/mol and 85.1kJ/mol in the low temperature zone according to the first order reaction model and 19.7 kJ/mol, 22.0 kJ/mol in the high temperature zone according to the three-way transport model. The reaction rate constant with variation of heating rate can be well predicted by the kinetic compensation relation of Gaur-Reed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.111-117
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• 2017

This study examined the material properties of Korean rice husk ash (RHA) according to the manufacturing process, and evaluated the feasibility of its use as a new admixture for high strength concrete. For this purpose, its particle size distribution, chemical composition, and microstructure were analyzed under various parameters, such as calcination temperature ($400^{\circ}C$, $650^{\circ}C$, and $900^{\circ}C$) and the inclusion of a milling process. X-ray fluorescence analysis confirmed that the silicon oxide ($SiO_2$) content of RHA was improved to more than 92% with a calcination process at $650^{\circ}C$ or higher. In addition, microstructural analysis showed that the RHA calcined at $650^{\circ}C$ has a porous structure. Because of this, the absorption capacity of the RHA was improved. On the other hand, when the milling process was applied, the porous structure was destroyed; thus, the absorption capacity tended to decrease further. Based on the analysis results, it was concluded that RHA calcined at $650^{\circ}C$ can be used as an admixture for high strength concrete, which possesses functions of both a shrinkage reducing agent and a pozzolanic activator.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.71-77
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• 2022

To increase biomass utilization, rice husk-based activated carbon (RHAC) followed by nitrogen plasma surface treatment was prepared and the electric double-layer capacitor performance was investigated. Through nitrogen plasma surface treatment, up to 2.17% of nitrogen was introduced to the surface of RHAC, and in particular the sample reacted for 5 min with nitrogen plasma showed dominant formation of pyrrolic/pyridine N functional groups. In addition, mesopores were formed on the RHAC material by the removal of silica, and the surface roughness of the carbon material increased by nitrogen plasma surface treatment, resulting in the formation of many micropores. As a result of cyclic voltammetry measurement, at a scan rate of 5 mV/s, the specific capacitance of the RHAC treated with nitrogen plasma increased up to 200 F/g, showing an 80.2% improvement compared to that of using untreated RHAC (111 F/g). This is attributed to the synergetic effect of the introduction of pyrrolic/pyridine-based nitrogen functional groups and the increase of the micropore volume on the surface of the carbon material. This study has a positive effect on the environment in terms of recycling waste resources and using plasma surface treatment.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.89-94
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• 1996

The purpose of this study is to investigate the workability and strength of concrete containing admixtures. For this purpose, four kinds of admixtures such as silica fume, fly ash, ground granulated blast-furnace, rice husk ash are selected and tested on the workability and strength according to the replacement ratio of them. As a result, considering their workability and strength, the optimum replacement ratio of them were obtained for each concrete containting admixtures.