• 한국도로학회논문집
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• 제18권6호
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• pp.105-113
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• 2016

OBJECTIVES : This study is to develop the optimum mixing proportions for cement concrete pavement with using recycled aggregates. METHODS : The mixture varied recycled coarse aggregates content from 50 % to 100 % to replace the natural coarse aggregates by weight. Tests for fundamental properties as a cement concrete pavement were conducted before and after hardening of the concrete. RESULTS : It was found that the variation in the amount of the recycled aggregate affected the compressive and flexural strength development, as well as the chloride ion penetration resistance. As the amount of the recycled aggregate content increased the compressive and flexural strength and the resistance to chloride ion penetration decreased. However, the resistance to freeze-thaw reaction was affected significantly. In addition, the gradation of the aggregate became worse and hence so did the coarseness factor as the recycled aggregate amount increased. CONCLUSIONS : The fundamental properties of the concrete with recycled aggregate does not seem to be appropriate when the recycled aggregate quality is not guaranteed up to a some level and its replacement ratio is over 50%. The optimized gradation of the aggregates should also be sought when the recycled aggregate is used for the cement concrete pavement materials.

• 한국식품영양과학회지
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• 제3권1호
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• pp.83-95
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• 1974

This experiment was initiated to determine the effective components of garlic during the growth stages and to regulate the contents artificially. The following results were obtained : 1. Alliin content was increased during its growth and showed drastic increase at maturing stage. 2. The kinds of free amino acids detected during growth stages were 15 for leaf growth, 14 for bulbing and 18 for maturing stage. The total content of free amino acids was high. est at maturing stage. 3. The optimum conditions for the maximum amounts of alliin and free amino acid determined by the binary interaction of Systematic Variations Method were 40% $NO_3^{-1}+60%\;SO_4^{-2}$, 62% $NO_3^{-1}+38%\;PO_4^{-3}$, 42% $K^{+1}+58%\;Ca^{+2}$ and 56% $K^{+1}+44%\;Mg^{+2}$ for alliin, and 72% $NO_3^{-1}+28%\;SO_4^{-2}$, 49% $NO_3^{-1}+51%\;SO_4^{-2}$, 45% $K^++55Ca^{+2}$ and 66% $K^{+1}+34%\;Mg^{+2}$ for free amino acid. 4. Ideal curve for alliin and free amino acid was attained by applying the binary interaction of Systematic Variations Method and it was possible to approach the optimum ionic proportion from the optimum contents on this curve.

• 농업과학연구
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• 제46권4호
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• pp.941-953
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• 2019

Biodiesels are being explored as a clean energy alternative to regular diesel, which causes pollution. In this study, the optimum conditions for producing biodiesel (BD) by combining beef tallow, an animal waste resource with a high saturated fatty acid content, and corn oil, a vegetable oil with a high unsaturated fatty acid content, were investigated, and the fuel properties were analyzed. Furthermore, Multivariate Analysis of Variance (MANOVA) was used to verify the optimum conditions for producing biodiesel. The influences of control factors, such as the oil blend ratio and methanol to oil molar ratio, on the fatty acid methyl ester and biodiesel production yield were investigated. As a result, the optimum condition for producing blended biodiesel was verified to be tallow to corn oil blend ratio of 7 : 3 (TACO7) and a methanol to oil molar ratio of 14 : 1. Moreover, the interaction between the oil blend ratio and the methanol to oil molar ratio has the most crucial effects on the production of oil blended biodiesel. In conclusion, the analysis results of the fuel properties of TACO7 BD satisfied the BD quality standard, and thus, the viability of BD blended with waste tallow as fuel was verified.

• Food Science and Biotechnology
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• 제14권2호
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• pp.190-195
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• 2005

The conditions for the extraction of effective substances from the stem of Opuntia ficus-indica were optimized by a response surface methodology. The total extract yield was maximized under the temperature of $97.77^{\circ}C$, at a time duration of 145.82 min and a water to sample ratio 16.59 mL/g. Moreover, the optimum conditions for the extraction of effective substances were as follows: $84.95^{\circ}C$, 156.50 min and a water/sample ratio of 7.46 mL/g for the phenolics content; and $97.11^{\circ}C$, 139.03 min and a water/sample ratio of 10.91 mL/g for the pectin content. The range of optimum extraction conditions in consideration of the physicochemical properties of the extracts were shown to be as $95-100^{\circ}C$ as the extraction temperature, 120-180 min as extraction time and a water to sample ratio of 5-18 mL/g.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권2호
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• pp.40-46
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• 2010

In this study, microwave irradiation, which is reflected by metals, was used to reduce the amount of sewage sludge, and the results were used to verify solubilization efficiency and determine optimum operation conditions. Biogas production and methane content of the gas under optimized conditions were measured with the biochemical methane potential (BMP) test. The sludge was taken from a thickened sludge tank at J sewage treatment plant (JSTP) in Seoul, Korea. For the experiments, 50 mL of sludge was filled in vessels and the vessels were irradiated with the power of 500, 600, 700, and 800W for 2~5 min. In addition, Fe powder was added by 0.01, 0.05, and 0.1 g to compare the efficiency with and without Fe powder. The results confirmed that solubilization efficiency was higher in the presence of Fe powder. The optimum conditions of 0.01 g addition of Fe powder with 800W irradiation for 5 min, yielded nearly 22.95% higher solubilization efficiency than without Fe powder. The BMP tests were carried out using sludge obtained from the experiments carried out under the optimum conditions. As a result, sludge subjected by 800W with 0.01 g of Fe powder for 5 min displayed the highest level of gas production and methane content. Through this study, it could be confirmed that solubilization efficiency increased by addition of Fe powder.

• 한국식품조리과학회지
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• 제28권6호
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• pp.655-663
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• 2012

This study was carried out response surface analysis for brown sauce optimization. Three factors of heating time (10, 20, 30, 40, and 50 min), the added gelatin content (0, 4, 8, 12, and 16%) and the added tomato paste amount (0, 6, 12, 18, and 24%) were encoded into 5 levels (-2, -1, 0, 1, 2). After the central synthesis plan was set up to produce samples in 16 pre-arranged conditions and the sensory tests were conducted, the investigation on optimum level of these factors was conducted. The scope of optimum conditions for extraction was established through reading the range of reaction surfaces superimposed between those representing sensory properties such as color, flavor, taste, viscosity and overall acceptability was established. In this study, it was found out that the scope of optimum conditions for brown sauce extraction was 30 min for heating time, 9.00% for gelatin content and 11.25% for tomato paste amount. The reliability test proved the mentioned scope to have a similar value to that of the estimated scope when compared to the experimental values which was observed through experiments conducted under the same conditions as applied to values predicted through RSM program, enabling the verification of the reliability of derived regression formula.

• 한국작물학회지
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• 제46권1호
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• pp.64-67
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• 2001

Snap bean is a new corp in Korea but believed to have a great deal of potentials for both domestic and overseas markets. The present study was performed to obtain the basic information about growth- and quality-related characteristics and to determinate the optimum seeding date and harvesting time for snap bean. Pod yield was significantly affected by seeding date. The highest pod yield was obtained from March 20 for determinate type and April 4 for indeterminate one, respectively, with the range of 13.0-23.7 t/ha. The pod length of indeterminate type was over 13cm, and the pod length was over 5 grams. The pod width for tested varieties was less than 1.0cm. Considering the pod growth characters such as pod length, pod width, and pod weight, the optimum harvesting time for immature pods of snap bean was supposed to be from 15 to 20 days after flowering. The daily yield of snap bean was begun to sharply increase from 15 days after the first flowering and the maximum yield was recorded at 30 days after flowering. For the accumulated yield, nearly 90% of total yield was obtained in 42 days after flowering.

• 한국환경농학회지
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• 제27권4호
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• pp.460-463
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• 2008

The change of glutelin contents in rice grain during the maturity period was investigated to determine optimum rice harvesting time. The glutelin content was increased with increasing time after heading. In this study, eight of glutelin subunits were found. Among the glutelin subunits, 7208-subunit (MW, 35 kD) contents was significantly increased at 65 days after heading compared with 55 and 60 days after heading. 7405-subunit (MW, 50 kD) contents was steadily increased with time after heading. The results showed that at 55th day after heading would be optimum time for harvest to get the low glutelin content of rice grain.

• 한국식품영양과학회지
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• 제27권1호
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• pp.80-86
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• 1998

This work was designed to determine the optimum roasting conditions with application of a pressure roaster for improving the roasting process of the Polygonatum sibiricum tea which has been roasting with a traditional method. Soluble solid content of the Polygonatum cibiricum tea was 63.16% in the tea roasted at 0.85kgf/$\textrm{cm}^2$(roasting pressure) and 13.9min(roasting time) which were maximum point by the ridge analysis. The optimum conditions predicted for each corresponding sensory properties of the Polygonatum cibirium tea were 0.87kgf/$\textrm{cm}^2$ and 9.2min in color, 0.89kgf/$\textrm{cm}^2$ and 9.7min in sweet 0.72kgf/$\textrm{cm}^2$ and 5.4min in burnt flavor, 0.89kgf/$\textrm{cm}^2$ and 9.9min in appetizing flavor, 0.87kgf/$\textrm{cm}^2$ and 9.3min in aftertaste, 0.89kgf/$\textrm{cm}^2$ and 10.0min in aroma, and 0.88kgf/$\textrm{cm}^2$ and 9.6min in overall acceptability of the tea. The optimum conditions based on the soluble solid content and sensory properties of the Polygonatum cibiricum tea, were 0.83~0.88kgf/$\textrm{cm}^2$ and 9.7~10.4min.

• Advances in concrete construction
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• 제8권2호
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• pp.127-137
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• 2019

Roller Compacted Concrete (RCC) is a zero slump concrete consisting of a mixture of cementitious materials, sand, dense graded aggregates and water. In this study, an attempt has been made to investigate the effect of aggregate type on strength and abrasion resistance of RCC made by using granulated blast furnace slag (GGBS) as partial replacement of cement. Mix proportions of RCC were finalized based upon the optimum water content achieved in compaction test. Two different series of RCC mixes were prepared with two different aggregates: crushed gravel and limestone aggregates. In both series, cement was partially replaced with GGBS at a replacement level of 20%, 40% and 60%. Strength Properties and abrasion resistance of the resultant mixes was investigated. Abrasion resistance becomes an essential parameter for understanding the acceptability of RCC for rigid pavements. Experimental results show that limestone aggregates, with optimum percentage of GGBS, perform better in compressive strength and abrasion resistance as compared to the use of crushed gravel aggregates. Observed results are further supported by stoichiometric analysis of the mixes by using basic stoichiometric equations for hydration of major cement compounds.