• Journal of the Korean Wood Science and Technology
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• v.45 no.2
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• pp.182-194
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• 2017

The optimum alkali pretreatment parameters (reaction time, reaction temperature and potassium hydroxide concentration) for facilitate the conversion into fermentable sugar (glucose) from steam exploded (severity log Ro 2.45) barley husk were determined using Response Surface Methodology (RSM) based on a factorial Central Composite Design (CCD). The prediction of the response was carried out by a second-order polynomial model and regression analysis revealed that more than 88% of the variation can be explained by the models. The optimum conditions for maximum cellulose content were determined to be 201 min reaction time, $124^{\circ}C$ reaction temperature and 0.9% potassium hydroxide concentration. This data shows that the actual value obtained was similar to the predicted value calculated from the model. The pretreated barley husk using acid hydrolysis resulted in a glucose conversion of 94.6%. This research of steam explosion and alkali pretreatment was a promising method to improve cellulose-rich residue for lignocellulosic biomass.

• Journal of Life Science
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• v.11 no.6
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• pp.568-573
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• 2001

Sea lettuce(Monostrima nitidum) were treated with several alkali agents on condition with water blanching at 9$0^{\circ}C$ for 10 min., and followed by drying and powdering, thus, the power samples treated and the not treated were then allowed to be stored at $25^{\circ}C$, dark place for 5 months. The sea lettuce powder samples were evaluated for green color intensity and volatile flavor at a month intervals. The green intensity of the samples were measured by using Hunter-lab colorimeter, therefore, the decoloration of greenness were seen in both of the samples treated and the not treated, but there were slight inhibitory effects on decoloration in the treated with alkali agents, especially in the treated with KHCO$_3$.The volatile flavor of the samples were collected by simultaneous distillation-extraction, and then the 31 flavor compounds were separated on HP-5 capillary column(25m$\times$0.25mm i.d) and identified by using GC-MS. From these results, it was presumed that the characteristic impact flavor compounds were $\beta$-cyclocitral, $\beta$-cyclohomocitral, ionene, $\alpha$-ionone and $\beta$-ionone. The total content of the characteristic impact flavor compounds decreased in the samples treated with alkali agents more alkali agents more than in the not treated, but lee decrease was observed in the treated with KHCO$_3$.

• Korean Journal of Food Science and Technology
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• v.29 no.1
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• pp.15-20
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• 1997

Changes in antioxidative substances-sesamol, sesamin and sesamolin - and mineral contents of sesame oil during refining processes have been studied to investigate the oxidative stability of oils during the storage at $70^{\circ}C$. Fe, Cu, Mg and Zn were nearly removed from the oil by the degumming process. During storage, the changes of total volatile contents in crude and degummed sesame oil were not noticeable but those in alkali-refined and deodorized sesame oil were increased at early period of the storage. The increases of hexanal and pentanal were most noticeable and their concentration was increased markedly in alkali-refined, bleached and deodorized sesame oil at early period of the storage. During refining processes and storage, sesamin was relatively stable but the content of sesamolin was decreased. The content of sesamol was decreased until alkali-refining process but increased during a bleaching process. The content of sesamolin tended to decrease with increasing of sesamol during storage.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.277-281
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• 1999

Dull grains segregated from F$_3$ and F$_4$ of the crosses between two dull mutants and a glutinous cultivar were compared with non-glutinous and glutinous segregants for their physicochemical properties. Amylose content of dull rice grain segregated from the dull/glutinous cross showed the intermediate value between glutinous and non-glutinous rice grain, whether it is controlled by the recessive or dominant gene. Alkali digestibility value (ADV) of dull rice grain was lower than that of glutinous or non-glutinous rice. A positive correlation was found between ADV and amylose content of homozygous non-glutinous or dull F$_4$ grains, but a negative relationship was observed in glutinous grains. Protein content of dull grain was significantly higher than that of glutinous or non-glutinous grain segregated from the same cross, while those of glutinous and non-glutinous grains were not different. Among gelatinization characteristics, initial pasting temperature and peak viscosity of dull grains were higher than glutinous rice, and were not different with non-glutinous grain. Hot, cool and consistency viscosities of dull grain were intermediate between glutinous and non-glutinous rices. Dull grains showed the highest breakdown viscosity and the lowest setback viscosity among the three endosperm types.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.3
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• pp.320-325
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• 1985

Relation between amylose and physical properties of milled rice was investigated. Amylose content was negatively and positively correlated with chalkiness and alkali solubility, respectively. No correlation was observed between amylose content and water uptake rate, cooked rice hardness or relative crystallinity. Relative crystallinity of the starch was negatively correlated with alkali solubility and water uptake rate.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.103-109
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• 2010

Anaerobic digestion has been widely used for the treatment of sludge, which is generated from the municipal and industrial wastewater treatment, for its volume reduction and methane production. Many researches on sludge pre-treatment have been carried out in order to enhance the performance of anaerobic digestion by increasing the hydrolysis of sludge which is the rate limiting step of anaerobic digestion. In this study, the effect of pre-treatment on sludge hydrolysis(solubilization), methane production and sludge reduction by anaerobic digestion after thermal, ultrasonic, and thermal-alkali sludge treatment were compared. Thermal-alkali treatment showed 67 and 70% solubilization with municipal and industrial wastewater sludge, respectively, while ultrasonic treatment and thermal treatment gave similar solubilization efficiency of 40% or more. Methane content of the anaerobic digestion gas reached 45~70% and pretreated sludge gave higher methane content than the control sludge. Methane production of thermal, ultrasonic, and thermal-alkali pre-treatment gave 2.6, 2.7, 3.5 times of municipal control sludge and 3.5, 4.1, 4.2 times of industrial control sludge, respectively. Sludge reduction of pre-treated sludge after anaerobic digestion gave 5~19% point higher than that of control sludge, and thermal-alkali treatment showed higher reduction efficiency than thermal and ultrasonic treatment. The results proved that pre-treatment contributed significantly not only for the methane production but also for the cost reduction of sludge treatment and disposal, and thermal-alkali treatment gave the best performance for the sludge treatment.

• International Journal of Highway Engineering
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• v.17 no.2
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• pp.1-11
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• 2015

PURPOSES : This study set out to investigate the fundamental properties of alkali-activated concrete (AAC) using modified slag as the pavement maintenance material. METHODS: The material properties of modified slag based alkali-activated concrete (MSAAC) were analyzed and evaluated against those of alkali-activated slag concrete (AASC). Several mix formulations were considered, including one MSACC and four AASCs. The main variables considered in the study were slump, air content, compressive strength, rapid chloride permeability test, scaling resistance, freeze-thaw test, XRD, SEM, and EDS. RESULTS: MSAAC exhibits a compressive strength in excess of 21 MPa six hours after curing. Also, the charge passed of the MSACC was found to be less than 2000 coulombs after seven days and about 1000 coulombs after 28 days. The weight loss determined from a scaling test did not exceed $1kg/cm^2$ in the case of the MSACC, but that of the AASCs had already exceeded $1kg/cm^2$ at the 10th cycle. Based on the results of the freeze-thaw test, the relative dynamic modulus of every mix was found to be in excess of 90%. An energy dispersive spectroscopy(EDS) analysis found that the weight rate percentage of the calcium and aluminum in the MSAAC mix is twice that of the AASC mixes. CONCLUSIONS : It was found that the MSAAC mix exhibits significantly better performance than AASC mixes, based on various fundamental properties.

• Journal of the Korea Concrete Institute
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• v.13 no.3
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• pp.213-220
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• 2001

Incorporation of wastes glass aggregate in mortar may cause crack and this may result in the strength reduction due to alkali-silica reaction(ASR) and expansion. The purposes of this study were to investigate the properties of alkali-silica expansion and strength loss through a series of experiments which had a main experimental variables such as waste glass aggregate contents, glass colors, fiber types, and fiber contents. The steel fibers and polypropylene fibers were used for constraining the ASR expansion and mortar cracking. From the result, green waste glass was more suitable than brown one because of low expansion. And in this accelerated ASTM C 1260 test of waste glass, pessimum content can not be found. Also, when used the fibers with waste glass, there is an effect on reduction of expansion and strength loss due to ASR between the alkali in the cement paste and the silica in the waste glass. Specially, adding 1.5 vol.% of steel fiber to 20% of waste glass, the expansion ratio was reduced by 40% and flexural strength was developed by up to 110% comparing with only waste glass(80$\^{C}$ H$_2$O curing).

• Journal of the Korean Ceramic Society
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• v.44 no.9
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• pp.471-476
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• 2007

The hydration mechanism of the $3CaO{\cdot}Al_2O_3-CaSO_4{\cdot}2H_2O$ system in the presence of alkali sulfates has been investigated. The early hydration rate of $3CaO{\cdot}Al_2O_3$ was accelerated by the addition of $Na_2SO_4$ and $K_2SO_4$. This is closely related to the formation of syngenite $(CaSO_4{\cdot}K_2SO_4{\cdot}H_2O)$, and the U-phase added $K_2SO_4$ and $Na_SO_4$ in the $3CaO{\cdot}Al_2O_3-CaSO_4{\cdot}2H_2O$ system, respectively. The formation of the rigid syngenite and U-phase structure led to rapid setting and decreases the sulfate content in the liquid phase of the hydrating cement to the extent that it cannot adequately retard the hydration of $3CaO{\cdot}Al_2O_3$. In case of the alkali sulfate not added to the $3CaO{\cdot}Al_2O_3-CaSO_4{\cdot}2H_2O$ system, the ettringite was transformed to monosulfoaluminate immediately after the consumption of gypsum. However, when the alkali sulfates were added to this system, the ettringite did not transform to monosulfoaluminate immediately even though the gypsum was completely consumed. There was a stagnation period to transform to the monosufoaluminate after the consumption of gypsum because the syngenite and U-phase remained as the sulfate source.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.4
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• pp.309-314
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• 2002

Rhtological properties of surimi gel from white fishes by acid (acid surimi) and alkali (alkali surmi) process and effect of chemicals on gelation were investigated by punch and dynamic tests. The breaking force and deformation values of heat-induced gel of acid surimi were less than their values of alkali and conventional surimi gel, and whiteness was greatly decreased, Gel point of acid surimi was decreased but it of alkali surimi was increased with increasing moisture content in the range of 80 to $85\%$. Storage modulus of acid surimi was the highest vaule in pH 6.8, but that of alkali surimi showed high value at neutral and slightly alkali pH. Propylene glycol increased storage modulus in $20\~50^{\circ}C$, hut urea and 2-mercaptoethanol suppressed it. Potassium bromide improved storage modulus in $20~80^{\circ}C$, The results suggest that alkai process is used for making surimi instead of conventional method.