• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.137-144
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• 2014

The PHC pile utilizing the air-cooled blast-furnace slag as coarse aggregate was studied. This research was progressed with the range from the indoor mixing design evaluation into the actual goods production. The physical properties of the PHC pile are determined to satisfy through the appropriate mixing design adjustments. However, it should eliminate the aggregates including CaO and MgO in SG when it utilize in an AC (autoclave) type manufacturing process. It satisfied the bending moment, shear strength, and compressive strength of KS F 4306 except the surface states of the pile.

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

• Journal of Environmental Science International
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• v.33 no.1
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• pp.17-25
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• 2024

This study aimed to determine the most suitable coir substrate mixing ratio for optimizing the growth and yield of the "lpduelkkae 1" cultivar. We comprehensively analyzed the physicochemical properties, growth, and yields of four different substrate combinations: perlite (coir with mixing ratios of 70:30 (PC30), 50:50 (PC50), and 30:70 (PC70)) and 100% coir (C100). The results revealed substantial differences in substrate properties. C100 exhibited the highest total porosity and the lowest solid phase, indicating excellent air permeability. The pH levels and electrical conductivity (EC) values ranged from 5.4-6.8 and 1.2-3.1 dS·m^-1, respectively. Leaf growth parameters, including length, width, and dry weight, showed positive correlations with high coir ratios, except for PC30. PC70 and C100 outperformed other substrates in stem growth, exhibiting superior stem diameter and fresh and dry weights. The quantity of marketable leaves was the highest in the C100 substrate. Furthermore, C100 comprised integrated levels of essential nutrients, such as Ca and Mg, owing to its high coir content. In conclusion, a coir ratio of approximately 70% (v/v) should be maintained in the substrate for creating an optimal cultivation environment. Furthermore, the selection of humidity-resistant varieties as well as precise nutrient and moisture management for different seasons and growth stages are crucial for a successful perilla leaf hydroponic cultivation.

• Economic and Environmental Geology
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• v.34 no.6
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• pp.507-522
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• 2001

At the Tongyeong mine, quartz, rhodochrosite (kutnahorite), muscovite, illite, pyrite, galena, chalcopyrite. sphalerite, acanthite, and hessite are the principal vein minerals. They were deposited under epithermal conditions in two stages. Ore mineral assemblages and associated gangue phases in stage can be clearly divided into two general associations: an early cycle (band) that appeared with introduction of most of the sulfides and electrum, and a later cycle in which base metal and carbonate-bearing assemblages (mostly rhodochrosite) became dominant. Tellurides and some electrum occur as small rounded grains within subhedral-to euhedral pyrite or anhedral galena in stageII. Sulfide mineralization is zoned from pyrite to galena and sphalerite. We have used computer modeling to simulate formation of four stages of vein genesis. The reaction of a single fluid with andesite host rock at 28$0^{\circ}C$, isobaric cooling of a single fluid from 26$0^{\circ}C$ to 12$0^{\circ}C$, and boiling and mixing of a fluid with both decreasing pressure and temperature were studied using the CHILLER program. Calculations show that the precipitation of alteration minerals is due to fluid-andesite interaction as temperature drops. Speciation calculations confirm that the hydrothermal fluids with moderately high salinities and pH 5.7 (acid), were capable of transporting significant quantities of base metals. The abundance of gold in fluid depends critically on the ratio of total base metals and iron to sulfide in the aqueous phase because gold is transported as an Au(HS)$_2$- complex, which is sensitive to sulfide activity. Modeling results for Tongyeong mineralization show strong influence of shallow hydrogenic processes such as boiling and fluid mixing. The variable handing in stageII mineralization is best explained by maltiple boilings of hydrothermal fluid followed by lateral mixing of the fluid with overlying diluted, steam-heated ground water. The degree of similarity of calculated mineral assemblages and observed electrum composition and field relationships shows the utility of the numerical simulation method in identifying chemical processes that accompany boiling and mixing in Te-bearing Au-Ag system. This has been applied in models to narrow the search area for epithermal ores.

• Korean journal of food and cookery science
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• v.29 no.3
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• pp.291-300
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• 2013

This study was conducted to develop the optimum mixing rates of a functional instant pumpkin gruel including pumpkin powder and to have the high preference to all age groups. The produced of this study were to optimum the composite recipe by making instant pumpkin gruel, respectively, with the different 16 experimental point with 3 replicates of the weight of pumpkin powder ($X_1$), roasted soybean flour ($X_2$) and gelatinized rice flour ($X_3$), and by quantities of the using response surface methodology(RSM). The color, pH, viscosity, and sensory characteristics(appearance, color, flavor, taste, viscosity, overall acceptability) were dependent parameters. The color of instant pumpkin gruel L value decreased with increasing amounts of pumpkin powder and a value and b value increased. pH and viscosity increased with increasing amounts of pumpkin powder and roasted soybean powder. The optimal mixing percentage of pumpkin powder, roasted soybean flour and gelatinized rice flour were 5.25 g, 3.00 g and 4.50 g for overall quality of 5.72 g, 4.30 g and 3.00 g for maximum score of overall organoleptic quality, respectively.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.330-343
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• 1997

Extraoral maxillofacial prostheses are essential for restoring facial structures that are lost as a result of congenital missing, injuries from accidents, surgical treatments of head and neck cancer. Recently, silicone is the most useful material for this purpose and is more advantageous than other maxillofacial prosthetic materials. However, there are some problems for long-term usage of silicone prostheses due to tear and color change. These are major contributing environmental factors to those problems that are such as ultraviolet light, cleansing agents, changes in humidity and successive adhesion and removal. The aim of this study is to evaluate the physical properties and color changes of maxillofacial prosthetic silicone material by those environmental factors using A-2186 silicone material (Factor II, USA) and two pigments, cadmium yellow medium and cosmetic red. Aluminium molds were fabricated according to the ASTM No. D412 & D624 specifications and resulted specimens from molds were fabicated and treated as follows. Control group and experimental I group were fabricated with 0.1% wt. pigment mixing in silicone elastomer and II-1 group, II-2 group of experimental II group were fabricated with 0.2%, 0.3% wt. pigment mixing in silicone elastomer, respectively. Control group was kept in darkroom at room temperature, I-1 group was kept under natural sunlight during 1week, I-2 group was soaked in 20% soap water during 1wk. I-3 group was successively adhered and removed 200 times on inner region of arm using Daro adhesive-33. Experimental II groups were kept in darkroom at room temperature. Instron universal testing machine was used to measure the % elongation, tensile strength, tear strength of control, experimental I, II groups and reflectance spectrophotometer(COLOR EYE-3000, Macbeth, USA) was used to measure the color differences between control group and experimental I group. The results were as follows : 1. When compared with control group, natural weathering group and 20% soap-water soaking group had no significant differences in % elongation(p>0.05). 2. 200 times successive adhesion and removal group, 0.2% wt. pigment group and 0.3% wt. pigment group had significant decreases in % elongation(p<0.05). 3. Natural weathering group, 20% soap-water soaking group and 200 times successive adhesion and removal group had no significant differences in tensile strength (p>0.05). 4. 0.2%, 0.3% wt. pigment groups had significant decreases in tensile strength(p<0.05). 5. Values of all experimental groups were decreased in tear strength. and 200 times successive adhesion and removal group had significant decrease in tear strength(p<0.05). 6. Natural weathering group and 20% soap-water soaking group had significant color differences(${\Delta}E$) and it could be detectable to naked eye(p<0.05). 7. Color differences between control group and 200 times adhesion and removal group were not detectable to the naked eye (${\Delta}E<1.0$).

• Korean journal of food and cookery science
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• v.27 no.6
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• pp.691-700
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• 2011

This study's objective is to determine the optimum mixing ratio of yam (Dioscorea japonica THUMB) powder and egg for the preparation of pasta. Response surface methodology revealed 10 experimental points, including two replicates for yam powder and egg. Yam pasta formulation was optimized using rheology. Yellowness(p<0.05) and redness displayed a linear model pattern, while lightness was represented by a quadratic model. The texture(p<0.05), including flavor(p<0.05) and overall quality(p<0.05) was measured as a sensory evaluation. In addition, mechanical properties displayed significant values in adhesiveness(p<0.05). These results showed that yam powder affects flavor and appearance, and egg affects adhesiveness and overall quality. The optimum formulations processed by numerical and graphical optimization were determined at 19.50 g of yam powder and 28.07 g of egg.

• The Journal of Advanced Prosthodontics
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• v.8 no.5
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• pp.372-379
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• 2016

PURPOSE. Alginate mixers available in the market do not have the automatic proportioning unit. In this study, an automatic proportioning unit for the alginate mixer and controller software were designed and produced for a new automatic proportioning unit. With this device, it was ensured that proportioning operation could arrange weight-based alginate impression materials. MATERIALS AND METHODS. The variation of coefficient in the tested groups was compared with the manual proportioning. Compression tension and tear tests were conducted to determine the mechanical properties of alginate impression materials. The experimental data were statistically analyzed using one way ANOVA and Tukey test at the 0.05 level of significance. RESULTS. No statistically significant differences in modulus of elastisity (P>0.3), tensional/compresional strength (P>0.3), resilience (P>0.2), strain in failure (P>0.4), and tear energy (P>0.7) of alginate impression materials were seen. However, a decrease in the standard deviation of tested groups was observed when the customized machine was used. To verify the efficiency of the system, powder and powder/water mixing were weighed and significant decrease was observed. CONCLUSION. It was possible to obtain more mechanically stable alginate impression materials by using the custom-made proportioning unit.

• Journal of the Korean Chemical Society
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• v.6 no.2
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• pp.176-197
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• 1962

Seasonal variations of chemical constituents of estuarine water at a definite station of the tidal flat in Guang Yang inlet have been determined for two days a month. The range and mean of the annual variations are as follows:Tidal variations through a year are as follows:1. Although the tidal value of pH is almost constant during one tidal cycle, it raises abruptly 0.1-0.2 intervals of pH value during the first period of flood.2. The lower values of chlorinity, magnesium and calcium contents have been determined the nearer the slack after ebb, and slightly higher during the first period of flood tide than the last of ebb. The tidal change of calcium contents is more remarkable than of magnesium.3. The higher per cent saturation values of dissolved oxygen, sometimes higher than 100 per cent, re determined the nearer the slack after ebb.4. The total nitrogen contents, relatively poor, varies accidentally during one tidal cycle, whereas phosphate-P and silicate-Si are rich at the slack after ebb and increase proportionally to the mixing percentage of fresh water. The average values, 52.2 and 18.5 of Si/P and N/P are greater than of the normal.5. The acid soluble iron contents, lower in winter than in summer, is also varies accidentally during one tidal cycle and the magnitude of the variation is large.6. The chemical composition considered from the value of Ca/Cl or Mg/Cl of estuarine water varies according to the chlorinity even at the high chlorinity of 18-19%.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.373-378
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to determine the optimum operational condition in lime adding process in water treatment plant(WTP). The mixing time at dissolution tank and sedimentation time at saturator for maintaining optimal turbidity condition of lime supernatant were 60~75 minutes and 75~95 minutes, respectively. There was no difference according to $CO_2$ adding methods such as $CO_2$ saturated water or $CO_2$ gas. But, $CO_2$ saturated water could be convenience at WTP in terms of pH control and quantitative dosing. To minimize generation of calcium carbonate products, the short time interval between adding of lime and $CO_2$ is most important. The lime should be added below 32 mg/l for preventing pH rising and generation of calcium carbonate products at the heating condition.