• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.7
• /
• pp.809-815
• /
• 2016

In this paper, the electrical values of resistance, current, and voltage condition of reactivity is analyzed by applying the direct current (DC) voltage in medium for stem cell regeneration treatment. The voltage response by medium is related to electrical stimulation in the process of induction of differentiation for stem cell and the differentiation condition can be checked depending on the response of voltage condition. If the voltage level is lower in reacting response of a medium, the stem cell stimulation condition is stable, and if the voltage changing level is higher, the stem cell stimulation condition is unstable and a considerable loss will be resulted in the differentiation process. In this research, the optimization of electrical stimulation condition is expected for possible stem cell regeneration treatment.

• Korean Journal of Food Science and Technology
• /
• v.35 no.2
• /
• pp.222-228
• /
• 2003

Optimum extraction conditions for yield, browning color, electron-donating ability, nitrite-scavenging effect, total polyphenol content, and tyrosinase-inhibitory activity of Flammulina velutipes were determined using response surface methodology through central composite design. Yield of F. velutipes was affected by ethanol concentration, and browning color improved more with the increase of ethanol concentration than microwave power. Nitrite-scavenging effect was improved with increasing ethanol concentration and decreasing microwave power. Electron-donating ability and total polyphenol content were improved with increasing ethanol concentration and microwave power. Tyrosinase-inhibitory effect increased more with decrease in microwave power than with ethanol concentration. The optimal range of extraction conditions for effective component of F. velutipes were $47.21{\sim}76.05$ watt of microwave power, $10.25{\sim}43.56%$ of ethanol concentration, and 5.72 min of extraction time.

• Korean journal of food and cookery science
• /
• v.19 no.4
• /
• pp.504-510
• /
• 2003

To optimize the preparation process of Jeung-Pyun, an experiment was derived, using a central composite design, to fmd the optimal mixing conditions. The addition of Paecilomyces japonica powder, the volume of Tak-Ju and the second fermentation time were independent variables, with the pH, volume, color, sensory and texture properties of the Jeung-Pyun selected as response variables. As the Paecilomyces japonica powder and fermentation time were increased, the b values and volume after the second fermentation also increased. The color of the Jeung-Pyun became deeper with increases in the Paecilomyces japonica powder and fermentation time, and was deepest on the addition of 30% Tak-Ju. The pH increased with increasing fermentation time of the Jeung-Pyun, and on the addition of 3% Paecilomyces japonica rapidly increased more than with the other groups. The optimal mixing conditions for the best quality Jeung-Pyun, with restricted conditions above a b value of 3, a color intensity above 3, and a volume of 40mQ and a pH of 4.02-4.04 after the second fermentation, were 4.0%, 20% and 45 mins for the Paecilomyces japonica powder, Tak-Ju and second fermentation time, respectively.

• Current Research on Agriculture and Life Sciences
• /
• v.7
• /
• pp.175-184
• /
• 1989

Kinetics of ascorbic acid and browning that may use on the optimization of food dehydration were evaluated. Banana was chosen for this as the representative test material. We have described the destruction of ascorbic acid and browning as first and zero order reactions. The temperature dependence between two reactions were conducted with Arrhenius equation. Finally we have operated SPSS computer programs reapeatedly that we found very dose value of the parameter between result of ascorbic acid and browning. The attained Kinetic models were well prepared for the value of result experiments and the models may use on optimization for dehydration progress. Destruction rate of ascorbic acid and browning rate were low at initiation of progress, increased to show maximum at the low moisture on mid-progress and then decreased gradually. Freeze drying showed the most constant quality of product in this case.

• Korean Chemical Engineering Research
• /
• v.61 no.4
• /
• pp.598-603
• /
• 2023

Electrochemical ammonia production using catalysts offers a promising alternative to the conventional Haber-Bosch process, allowing for ambient temperature and pressure conditions, environmentally friendly operations, and high-purity ammonia production. In this study, we focus on the nitrogen reduction reactions occurring on the surfaces of ruthenium catalysts, employing first-principles calculations. By modeling reaction pathways for nitrogen reduction on the (0001) and (1000) surfaces of ruthenium, we optimized the reaction structures and predicted favorable pathways for each step. We found that the adsorption configuration of N₂ on each surface significantly influenced subsequent reaction activities. On the (0001) surface of ruthenium, the end-on configuration, where nitrogen molecules adsorb perpendicularly to the surface, exhibited the most favorable N₂ adsorption energy. Similarly, on the (1000) surface, the end-on configuration showed the most stable adsorption energy values. Subsequently, through optimized hydrogen adsorption in both distal and alternating configurations, we theoretically elucidated the complete reaction pathways required for the final desorption of NH₃.

• Korean Journal of Food Science and Technology
• /
• v.35 no.5
• /
• pp.777-782
• /
• 2003

Response surface methodology (RSM) was used to monitor the characteristics of ethanol extracts from Hericium erinaceus. A central composite design was applied to investigate the effects of independent variables, ethanol concentration $(X_1)$, and sample ratio $(X_2)$ on dependent variables, soluble solid $(Y_1)$, total phenols $(Y_2)$, crude protein $(Y_3)$, electron donating ability $(Y_4)$, and browning color $(Y_5)$ of the extracts. As the sample ratio increased, the soluble solid content increased. Ethanol concentration played a minor role. Total phenols and crude protein increased with sample ratio. Sample ratio had a greater effect than alcohol concentration in the extraction of soluble solid, total phenols, crude protein, and browning color, with an exception of electron donating ability. The optimum ranges at 2 hr extraction was $3.9{\sim}5.0\;g/l00\;mL$ in sample ratio and $36{\sim}52%$ in ethanol concentration. Predicted values at the optimized conditions were acceptable when compared to experimental values.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.46 no.4
• /
• pp.349-360
• /
• 2020

Bio-conversion manufacturing technology has been developed to produce ginsenoside Rd which is increasingly in demand as a cosmetic material due to various possibilities related to improving skin function. In order to convert ginsenoside Rb1 which is contained in red ginseng saponin (RGS) into Rd, several commercial enzymes were tested. Viscoflow MG was found to be the most efficient. In order to optimize the conversion of RGS to ginsenoside Rd by enzymatic transition was carried out using response surface methodology (RSM) based on Box-Behnken design (BBD). The main independent variables were RGS concentration, enzyme concentration, and reaction time. Conversion of ginsenoside Rd was performed under 17 conditions selected according to BBD model and optimization conditions were analyzed. The concentration of the converted ginsenoside Rd ranged from 0.3113 g/L to 0.5277 g/L, and the highest production volume was obtained under condition of reacting 2% RGS and 1.25% enzyme for 13.5 hours. Consequently, RGS concentration, enzyme concentration which is 0.05 less than p-value and among the interactions between the independent variables, the interaction between enzyme concentration and reaction time was confirmed to be the most influential.

• Polymer(Korea)
• /
• v.32 no.4
• /
• pp.385-389
• /
• 2008

Chain propagation and chain transfer in anionic polymerization of hexafluoropropylene oxide were investigated under various reaction conditions such as the stabilization of reaction temperature, the amount of hexafluoropropylene solvent, and the feeding rate of hexafluoropropylene oxide monomer. Anionic initiator for the polymerization was synthesized from cesium fluoride and hexafluoropropylene oxide in tetraethyleneglycol dimethylether. It was possible to obtain a high molecular weight poly(HFPO) ($M_w$ 14800) using the anionic initiator in conditions of stabilized reaction temperature, and optimized addition of solvent and monomer feeding (HFP/initiator mole ratio=31.5 and HFPO feeding rate=11.67 g/hr). Otherwise, chain transfer reaction in anionic polymerization was increased. From the results of molecular weight in various reaction conditions, it was found that chain propagation and chain transfer in anionic polymerization of HFPO were very sensitive to reaction conditions.

• Journal of Life Science
• /
• v.13 no.6
• /
• pp.794-798
• /
• 2003

Batch production of (S)-phenyl oxirane was investigated using epoxide hydrolase activity of Rhodosporidium toruloides SJ-4. Effect of reaction condition of asymmetric biohydrolysis of racemic phenyl oxirane was analyzed and optimized by response surface methodology. The optimal conditions of pH, temperature and DMSO cosolvent ratio were 7.4, $34^P\circ}C$, and 2.3%(v/v), respectively. The final yield was enhanced up to 67%, and reaction times required to reach 99% ee (enatiomeric excess) decreased down to 50% by response surface methodology Enantiopure (S)-phenyl oxirane with 100% enantiopurity and 24% yield (theoretical yield = 50%) was obtained from racemic substrate.

• Food Science and Preservation
• /
• v.13 no.3
• /
• pp.363-368
• /
• 2006

This study was performed to develop flavor materials from Elsholtzia ciliata Hylander with analyzing functionality and aroma profile and to optimize supercritical fluid extraction method and optimum condition. The qualities of water extracts such as total yield total phenolic compound electron donation ability, estragole and L-carvone, were affected by extraction pressure than time. The response variables had significant with pressure than with time and the established polynomial model was suitable(P>0.05) model by Lack-of-Fit analysis. The optimum extraction conditions which were limited of maximum value for dependent variables under experimental conditions based on central composite design were 238 bar and 42 min.