• Journal of Welding and Joining
• /
• v.18 no.5
• /
• pp.90-97
• /
• 2000

Effect of alloy elements on joinability of insert metal for liquid phase diffusion bonding of heat resistant alloys was investigated in this study. Also, optimum chemical composition of insert metal was explained using interpolation method. The insert metals utilized was commercial Ni-base amorphous foils and newly developed Ni-base filler metals with B, Si and Cr in this study. Melting point and critical interlayer width(CIW) decreased with increasing additional amount of B, Si and Cr, melting point lowering element of the insert metal. Optimized chemical composition of insert metals could be estimated by interpolation method. The optimum amount of B, Si, Cr addition into the insert metal were found to be about 3%, 4% and 3%, respectively. The measured characteristic values, melting point, microhardness in the bonded interlayer and CIW of the insert metals were the almost identical to ones of the calculated results by interpolation method.

• Journal of the Korean institute of surface engineering
• /
• v.5 no.2
• /
• pp.1-4
• /
• 1972

We have studied about the optimum chemical etching and sensitizing conditions of the plating on plastics. As specimen 'Mitzubishi Nobren MM2A' was used. The results were as follow. 1) The optimum chemical etching conditions. Etched the specimens for $10{\sim}40$ minutes at $70{\sim}80^{\circ}C$ with the etching solution of table 1, and for $10{\sim}15$ minutes at $65{\sim}70^{\circ}C$ with the etching solution of table 2 Table 1. Etching solution (I) Composition : $H_2SO_4(95%)-Component : 250 ml, Composition : $H_3PO_4(85%)$ - Component : 75ml, Composition : $K_2Cr_2O_7$ - Component : 12.5g, 2) The optimum sensitizing conditions. Sensitized the specimens for $60{\sim}90$ seconds at $25^{\circ}C$ with the sensitizing solution of table 3 Table 2. Etching solution (II) Composition : $H_2SO_4(95%)$ - Component : 22.5ml, Composition : $H_3PO_4(85%)$ - Component : 15ml, Composition : $CrO_3$ - Component : 105g, Composition : Water - Component : 150 ml, Table 3. Sensitizing solution Composition : $SnCl_2$ - Component : 9g, Composition : HCl(35%) - Component : 36ml, Composition : Water - Component : 300 ml

• Asian-Australasian Journal of Animal Sciences
• /
• v.19 no.10
• /
• pp.1490-1495
• /
• 2006

The purpose of this research was to develop an optimum composition model for a new synbiotic fermented dairy product with high probiotic cell counts, and to experimentally verify this model. The optimum composition model indicated the growth promoter ratio that could provide the highest growth rate for probiotics in this fermented product. Different levels of growth promoters were first blended with milk to improve the growth rates of probiotics, and the optimum composition model was determined. The probiotic viabilities and chemical properties were analyzed for the samples made using the optimal formula. The optimal combination of the growth promoters for the synbiotic fermented milk product was 1.12% peptides, 3% fructooligosaccharides (FOS), and 1.87% isomaltooligosaccharides (IMO). A product manufactured according to the formula of the optimum model was analyzed, showing that the model was effective in improving the viability of both Lactobacillus spp. and Bifidobacterium spp.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.9
• /
• pp.2011-2016
• /
• 2009

To resolve the differentiation problem of acetone and acrolein in the analysis of carbonyls by high-performance liquid chromatography (HPLC), we investigated the optimum analytical conditions for their separation. Carbonyl compounds were collected by 2,4-dinitrophenylhydrazine (DNPH)-coated cartridges. We examined the influence of three experimental variables: temperature (25, 30, 40, 50 and 60 ${^{\circ}C}$), flow rate (1.0 and 1.2 mL/min), and relative mobile phase composition (among acetonitrile, water and tetrahydrofuran). The experimental results revealed the optimum analytical condition of a flow rate of 1.2 mL/min, temperature of 32 ${^{\circ}C}$ and mobile phase composition of acetonitrile: water: tetrahydrofuran = 34 : 52.8 : 13.2. The analysis of indoor air composition indicated that acrolein and acetone comprised 11% and 42% of all aldehydes, respectively.

• YAKHAK HOEJI
• /
• v.33 no.2
• /
• pp.111-117
• /
• 1989

The optimum reaction conditions for the acid consuming capacity of aluminum silicate synthesized from the reaction of sodium silicate solution and potassium aluminum sulfate solution were investigated by Box-Wilson experimental design, and the micromeritic properties were examined by the means of BET $N_2$ adsorption, Hg penetrometer and methylen blue adsorption. The chemical composition of the samples were analyzed by gravitic method. The results were found to be as follows: optimum reaction temperature $54.7^{\circ}C$, both concentrations of reactant soln 15.7%, reactants molar ratio (Al/Si) 0.5 and drying temperature $65.0^{\circ}C$. The acid consuming capacity of the sample prepared by above optimum conditions was 68 ml and the chemical composition was $Al_2O_3{\cdot}3.6SiO_2{\cdot}3H_2O$. The relationship between acid consuming capacity and micromeritic properties could not found in the range of experiments. Therefore, it is assumed that the acid consuming mechanism of aluminum silicate depends on the neutralization of $Al_2O_3$ and buffer action of $SiO_2$ in sample.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.1
• /
• pp.56-61
• /
• 1997

Lead zirconate titanate (PZT) thin fills were deposited onto the Pt/Ti/SiO2/Si substrate by the pulsed laser deposition with the second harmonic wavelength (532 nm) of Nd:YAG laser. In order to determine the optimum conditions for the film deposition, the phase of the films were investigated as functions of ambient oxygen pressure, substrate temperature, and laser fluence. Also the chemical composition analysis was conducted for the PZT films deposited under various ambient oxygen pressure. When the distance between substrate and bulk PZT target is set to 20 mm, the optimum conditions have been determined to be 3 torr of oxygen pressure, 1.5 J/cm2 of laser fluence, and 823-848(±10) K range of substrate temperature. At these conditions, perovskite phase PZT films were obtained on platinized silicon. The chemical composition of the films is very similar to that of PZT bulk target. The physical structure of the deposited films analyzed by scanning electron microscopy shows a columnar morphology perpendicular to the substrate surface. Capacitance-Voltage hysteresis loop measurements show also a typical characteristics of ferroelectric thin film. The dielectric constant is found to be 528 for the 0.48 μm thickness of PZT thin film.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.20 no.2
• /
• pp.131-138
• /
• 2000

This experiment was carried out during the period from September, 1997 to October, 1998 to determine the effect of fermented saw-dust pig manure (FSP) application on the herbage production on a mixed pasture in the Cheju brown volcanic ash soil. Split plot design (main plot: 3 nitrogen application levels of 0, 150 and 300 kgiha; sub plot: 4 pig sawdust manure levels of 0, 3, 6 and 12 tonha) was used. Plant height and dry matter yield increased significantly with an increase of nitrogen and FSP level. There was no difference in the botanical composition of grasses as affected by FSP application level, but herbage yields of grass species were increased by nitrogen application compared to that without nitrogen application. Botanical composition of white clover decreased with an increase of nitrogen application, but increased with an increase of FSP application level. Percentages of weeds were not affected by application rates of chemical nitrogen fertilizer and swine manure in the mixed species pasture. Nitrogen, phosphorus, and potassium contents of species in the pasture significantly increased with increasing application rates of nitrogen fertilizer. In conclusion, it would be an optimum to apply 150 kgha of inorganic chemical fertilizer and plus either 3 or 6 toniha of fermented swine manure with sawdust for optimum production of mixed pasture on Cheju Island. (Key words : Herbage production, Botanical composition, Morphology, Plant mineral contents)

• Applied Chemistry for Engineering
• /
• v.8 no.2
• /
• pp.315-319
• /
• 1997

In this study, the optimum analytical conditions for determination of distribution of propylene oxide in a nonionic surfactant and separation of fatty alcohols were investigated by Reversed Phase High Performance Liquid Chromatography. To analyse the distribution of propylene oxide (PO) and carbon chain length of a fatty alcohol, we derivatized samples for the purpose of using a UV detector. Also, we studied the influences of columns and mobile phase composition to obtain the optimum separation conditions. In our experiment, Waters Symmetry $C_8(3.9{\times}150mm)$ column was used. And the optimum condition were obtained by gradient elution with methanol and water as the mobile phase. In the plot of log k' vs composition of water in the binary phase, the linerality was very good. We ploted the calibration curve to conform the quality of fatty alcohol, a good linerality was obtained.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.27 no.2
• /
• pp.57-71
• /
• 1985

The characteristics of compaction and unconfined compressive strength were investigated by mixing with lime to all soils adjusted by given percentages of two kinds of clays to sand to obtain the most effective distribution of grain size and the optimum lime content for soil stabilization. In addition, unconfined compressive strength and durability tested by adding of sodium metasilicate, sodium sulfate, sodium carbonate, sodium gydroxide and magnesium oxide to lime-soil mixture mixed with 8 percent lime to adjusted soil having the mixing percentage of 60 percent of cohesive black clay and 40 percent of sand by weight to get the effect and the optimum content of chemicals. The results obtained were as follows; 1.With the addition of more lime, the optimum moisture content was increased, and the maximum dry density was decreased, whereas the more the amount of clay and the less was the maximum drt density. 2. In the soil having more fine grain size the unconfined compressive strength was larger in the earlier stage of curing period, in accordance with the longer period, the mixing percentages of sand to clay showing the maximum unconfined compressive strength, on the basis of 28-day strength, were 60% : 40% (black clay) and 40% : 60% (brown clay) respectively. 3. The reason why the soil adjusted with black clay was remarkably bigger in the unconfined compressive strength than ones adjusted with brown clay for all specimen of lime-soil mixture was the difference in the kind of clay, the amount of chemical compositions the value of pH. Black clay was mainly composed of halloysite that reacted with lime satisfactorily, whereas the main composition of brown clay was kaolinite that was less effect in the enhance of unconfined compressive strength. Also the difference of unconfined compressive strength was because black clay was larger in the amount of composition of calcium oxide and magnesium oxide in the value of pH affecting directly on the unconfined compressive strength of lime-soil mixture than brown clay. 4. In the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40%, on the standard of 7-day strength, the effect of chemical was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium hydroxide and sodium metasilicate. 5. The optimum amount of chemical being applicable to the maximum unconfined compressive strength of lime-chemical-soil mixture was 1 percent by weight for air dry soil in the case of adding sodium carbonated and 0.75 percent on sodium hydroxide, the unconfined compressive strength was increased continuously with increase of the amount of chemical up to 2 percent of chemical content is the lime-chemical-soil mixture added sodium metasilicate, sodium sulfate and magnesium oxide. 6. It was considered that the chemical played and accelerant role of early revelation of strength because the rate of increase of unconfined compressive strength of all of lime-chemical-soil mixtures was largest on the 7-day cured specimen. 7. The effect of test on freezing and thawing after adding suitable amount of chemical on the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40% was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium metasilicate and sodium hydroxide.

• Korean Chemical Engineering Research
• /
• v.53 no.1
• /
• pp.6-10
• /
• 2015

Enzyme fuel cells were composed of enzyme anode and PEMFC cathode. Enzyme anodes was fabricated by compression of a mixture of graphite particle, glucose oxidase as a enzyme and ferrocene as a mediator, and then coated with Nafion ionomer. Open circuit voltage (OCV) were measured with variation of anode manufacture factors, to find optimum condition of enzyme anode. Optimum pressure was 9.0 MPar for enzyme anode pressing process. Highest OCV was obtained at 60% graphite composition in enzyme anode. Optimum glucose concentration was 1.7mol/l in anode substrate solution and enzyme activity of anode was stable for 7 days.