• Journal of The Korean Society of Grassland and Forage Science
• /
• v.16 no.2
• /
• pp.147-154
• /
• 1996

Rye(Secale cereale L.) shows lower dry matter yield and nutrient content when it was harvested before wintering. This study was conducted to investigate how effect forage rape(Brassicu napus Subsp oleifera), which carries early maturity and can be harvested before wintering, on the increase of the forage yield and nutrient content when rye was sown mixed with the rape. Optimum sowing rate of the rye/rape mixture was also pursued in this study. The five treatment of rye single, rape single, ryel20+rape 1Okg/ha, rye84+rape 7kg/ha and rye60+rape 5kg/ha were sown on 2 September 1989. Rape single plot was cut one time(l9 November 1989) and the other plots were cuted two times(19 November 1989 and 20 May 1990). In botanical composition of the mixtures, rape recorded dominant ratio with 64~69% at the autumn cut. The rye84+rape 7kg/ha mixture plot marked the highest dry matter yield with 4.46t/ha among all the experimental plot at the autumn cut(P<0.05). In year total yield of dry matter(t/ha), rye single, rape single, rye120+rape IOkg/ha, rye84+rape 7kg/ha and rye60+rape 5kg/ha marked 13.6, 4.1, 12.7, 12.9 and 11.8, respectively. In crude protein content, the rye single plot was 17.2% at the autumn cut on the other hand the mixture plots showed increasing tendency with 18.0~19.9%. In crude fiber content, the mixture plots were remarkably lower than rye single plot. In year total yield of crude protein, rye84+rape 7kg/ha mixture plot showed the highest yield with 1.6lt/ha among all the experimental plots. Ratio of crude protein yield to crude fiber yield, rye84+rape 7kg/ha tended to be higher than the other mixture plots. It is confirmed that the rye/rape mixture can produce more forage than the rye single cropping when they are harvested in late autumn, besides the mixture forage contains higher crude protein than that rye single forage. It can be said that the rydrape mixture is more useful than the rye single cropping, and optimum sowing rate of the mixture is 84kg/ha of rye+7kg/ha of rape.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.784-787
• /
• 2007

A process flowsheet simulation model based on ASPEN PLUS was developed to investigate the effect of co-gasification of coal and rice husk on the gasifier performance and pollutant emissions in IGCC power plant. The analyses were done for an 02-blown, pulverized gasifier using coal and rice husk as feedstock, parameter employed the blending ratio of rice husk in coal were investigated. From the simulation results, it was found that gaseous pollutant emissions were reduced substantially with the increase of the blending ratio of rice husk. An optimum range between 15% and 25% rice husk-to-coal ratio was found to be the optimum point in terms of gaseous pollutant emission per energy output for sui fur and nitrogen compounds.

• Journal of Environmental Health Sciences
• /
• v.22 no.4
• /
• pp.82-90
• /
• 1996

This study was performed to find the optimum mixing ratio of paper waste in composting of mixture of swine feces and newspaper. Using the experimental setting of aeration rate which was found in the experiment carried out priorly, and moisture contents reported in other literature, just the initial C:N ratios were differentiated by mixing different amount of newspaper with the same amount of swine feces. This study was carried out by operating 4 experimental cornposting reactors of bench scale for 3 weeks. The followings are the conclusions that were derived from this study. 1. During composting reaction, the C:N ratio of each cornposter was decreased. Degree of decrease was in order of run 3, run 2, run 4, and run 1 of which initial C:N ratio was 30, 25, 35, and 20 respectively. All of the final composts were found to be completed composting reaction. 2. Ash contents of each reactor increased rapidly in order of run 3, run 2, run 4, and run 1. The absolute values of quadratic effect coefficients of each second order regression function was 0.059, 0.038, 0.032, and 0.030 respectively. Ash contents evolution trend had a linear correlation with the C:N ratio trend. (r=-0.96932, p<0.05) 3. The range of highest temperatures reached during composting was 47.2-53.5$\circ$C. Those were not significantly different from one another. Thermophilic temperatures were maintained in the range of 48-108 hours. 4. Contents of heavy metal detected in the final compost were lower than those of Korean and European standards. 5. Concentration range of Nitrogen in the final compost was 1.11-2.27%, and that of phosphorus was 8.40-10.70 mg/kg. 6. The optimum C:N ratio which has been proposed without the consideration of types of bulking agents should be re-examined. Biodegradabilities of each bulking agents was thought to be important factor when determining the optimum initial C:N ratio for cornposting.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.13 no.1
• /
• pp.45-50
• /
• 2006

Papers were prepared from cut cocoons and mulberry branches, which are byproducts from sericulture industry. The long filament of silk should be cut into appropriate length in order to prepare paper and this was achieved by chemical method. By a mixture of sodium hydroxide and sodium carbonate solution, the silk filaments were cut into short fibers (less than 1 mm in length). Since the short silk fibers (sSf) could not bind each other by itself, starch and poly(ethylene oxide)(PEO) were added as a bonding agent. When starch and PEO were used in a ratio of 3:7, the silk papers had optimum mechanical properties for paper. Fibers from the skin of mulberry branches (MBF) were added to sSf to enhance the mechanical properties of pure silk paper. Bleaching of MBF was performed with a mixture of hydrogen peroxide and sodium silicate. The mechanical properties were greatly enhanced and the optimum blend ratio of MBF and sSf were 7:3. The mulberry/silk paper has good absorption property against formaldehyde, and therefore, the paper could be applied as a wall paper for preventing the sick house syndrome.

• Nuclear Engineering and Technology
• /
• v.31 no.2
• /
• pp.133-138
• /
• 1999

Research on the etching reaction of UO$_2$ with CF$_4$/O$_2$gas mixture plasma is carried out. The reaction rates are investigated as a function of CF$_4$/O$_2$ ratio, plasma power, and substrate temperature. It is found that there exists an optimum CF$_4$/O$_2$ ratio around 4:1 at all temperatures up to 37$0^{\circ}C$ and surface analysis using XPS X-ray Photoelectron Spectroscopy) confirms the result. Peak rate at the optimum gas composition increases with increasing temperature. Highest rate obtained in this study leaches 1050 monolayers/min. at 37$0^{\circ}C$ under r. f. power of 150 W, which is equivalent to about 0.5${\mu}{\textrm}{m}$/min. The rate also increases with increasing r. f. power, thus, higher power and higher substrate temperature will undoubtedly raise the etching reaction rate much further. This reaction seems to be an activated process, whose activation energy will be derived in the following experiments.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.412-419
• /
• 2009

Large quantity of extra soils discharged from excavation site in Songdo area can be treated by hardening agents and utilized in surface stabilized layer overlying thick reclaimed soft soil deposit. Though surface layer stabilization method using cement or lime for very soft soils has been studied in recent years, but studies on moderately soft clayey silt has not been tried. The purpose of this research is to investigate optimum mixing condition for stabilizing Songdo marine soil with low plasiticity. The optimum mixing conditions of hardening agents with Songdo soil such as kind of agents, mixing ratio, initial water content and curing time are investigated by uniaxial compression test and laboratory vane test. The results indicate that strength increases with high mixing ratio and long curing time, while decreases drastically under certain water content before mixing. Finally, optimum mixing condition considering economic efficiency and workability with test results was proposed.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.21 no.3
• /
• pp.632-640
• /
• 1997

Changes in surface properties and detergency of sunactant mixtures were investigated in order to study the optimum mixing ratio of anionic and nonionic surfactants by measuring surface tension, interfacial tension, suspendability, and emulsification as a Amction of mixing ratio. Also, surface tension and detergency of the surfactant mixtures were determined with the increase of water-hardness or temperature. The results were as follows: the addition of NPE to anionic surfactant solutions (LAS or SDS) by 0.1 mole fraction remarkably decreased surface tension. NPE (n=15)/anionic surfactant mixtures showed a synergistic effect in lowering interfacial tension and emulsification, but NPE (n=7.5)/anionic surfactant mixtures did not. In suspension stability, however, synergism appeared when LAS or 505 was mixed with both of NPE's. With respect to the hydrophile of NPE, NPE (n=15) was more effective than NPE (n=i.5) in improving suspension stability. Detergency of LAS/NPE mixture changed almost linearly with mixing ratio, but that of SDS/NPE mixture increased remarkably by the addition of 0.1 or 0.2 mole fraction of NPE at all temperatures. As the temperature increased, surface tension of surfactant mixtures decreased and detergency was improved, but their synergistic effect decreased. In hard water, the mixtures showed better detergency than single surfactuant solutions.

• Applied Microscopy
• /
• v.2 no.1
• /
• pp.1-6
• /
• 1972

The Optimum Conditions of Preparing barium Ferrite from $BaCO_3$ and $Fe_2O_3$ are Sought for with electron microscope. At first to find the optimum sintering temperature, the mixture in 1 : 3 mole ratio. Sintered primarily at $700^{\circ}C$ for an hour, is Sintered secondary at $960^{\circ}C{\pm}10,\;1040^{\circ}C{\pm}10,\;1120^{\circ}C{\pm}10,\;1200^{\circ}C{\pm}10,\;1250^{\circ}C{\pm}10,\;1330^{\circ}C{\pm}10$, respectively for an hour. at the optimum temperature,abtained in this way. Sintering time is varied from 10 minutes to 120 minutes with 10 minutes intervals. Through the experiment, It is found that the optimum temperature of $1200{\sim}1250^{\circ}C$ and optimum time of half-one hour.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.30 no.5A
• /
• pp.433-442
• /
• 2010

A control of chloride diffusion coefficient is very essential for service life of reinforced concrete (RC) structures exposed to chloride attack so that much studies have been focused on this work. The purpose of this study is to derive the intended diffusion coefficient which satisfies intended service life and propose a technique for optimum concrete mixture through genetic algorithm(GA). For this study, 30 data with mixture proportions and related diffusion coefficients are analyzed. Utilizing 27 data, fitness function for diffusion coefficient is obtained with variables of water to binder ratio(W/B), weight of cement, mineral admixture(slag, flay ash, and silica fume), sand, and coarse aggregate. 3 data are used for verification of the results from GA. Average error from fitness function is observed to 18.7% for 27 data for diffusion coefficient with 16.0% of coefficient of variance. For the verification using 3 data, a range of error for mixture proportions through GA is evaluated to 0.3~9.3% in 3 given diffusion coefficients. Assuming the durability design parameters like intended service life, cover depth, surface chloride content, and replacement ratio of mineral admixture, target diffusion coefficient, where exterior conditions like relative humidity(R.H.) and temperature, is derived and optimum design mixtures for concrete are proposed. In this paper, applicability of GA is attempted for durability mixture design and the proposed technique would be improved with enhancement of comprehensive data set including wider range of diffusion coefficients.

• Computers and Concrete
• /
• v.17 no.5
• /
• pp.629-638
• /
• 2016

Optimization of the concrete mixture design is a process of search for a mixture for which the sum of the cost of the ingredients is the lowest, yet satisfying the required performance of concrete. In this study, a statistical model was carried out to model a cost effective optimal mix proportioning of high strength self-compacting concrete (HSSCC) using the Response Surface Methodology (RSM). The effect of five key mixture parameters such as water-binder ratio, cement content, fine aggregate percentage, fly ash content and superplasticizer content on the properties and performance of HSSCC like compressive strength, passing ability, segregation resistance and manufacturing cost were investigated. To demonstrate the responses of model in quadratic manner Central Composite Design (CCD) was chosen. The statistical model showed the adjusted correlation coefficient R2adj values were 92.55%, 93.49%, 92.33%, and 100% for each performance which establish the adequacy of the model. The optimum combination was determined to be $439.4kg/m^3$ cement content, 35.5% W/B ratio, 50.0% fine aggregate, $49.85kg/m^3$ fly ash, and $7.76kg/m^3$ superplasticizer within the interest region using desirability function. Finally, it is concluded that multiobjective optimization method based on desirability function of the proposed response model offers an efficient approach regarding the HSSCC mixture optimization.