• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.575-580
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• 2020

In this study, we simulated an amine regeneration process with heat-stable salts removal unit. We derived the optimal operating conditions considering the flow rate of waste, the removal rate of heat-stable salts, and the loss rate of MDEA (methyl diethanolamine). In the amine regeneration process that absorbs and removes acid gas, heat-stable salt impairs the absorption efficiency of process equipment and amine solution. An ion exchange resin method is to remove heat-stable salts through neutralization by using a strong base solution such as NaOH. The acid gas removal process was established using the Radfrac model, and the equilibrium constant of the reaction was calculated using Gibbs free energy. The removed amine solution is separated and flows to the heat-stable salts remover which is modeled by using the Rstoic model with neutralization reaction. Actual operation data and simulation results were compared and verified, and also a case study was conducted by adjusting the inflow mass of removal unit followed by suggesting optimal conditions.

• Korean Journal of Microbiology
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• v.46 no.3
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• pp.248-254
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• 2010

To define the optimum conditions for the mass production of four antifungal Pseudomonas spp. isolated from soil, we have investigated culture conditions and effects of various nutrient sources on the bacterial growth and evaluated antagonistic activity against Rhizoctonia solani and Sclerotinia homoeocarpa, plant pathogens. The optimum temperature and pH for the growth of these isolates were determined as pH 7.0 and $20^{\circ}$ or $25^{\circ}C$, respectively. Sucrose, tryptone, and $K_2HPO_4$ generally were more adequate for better growth as carbon, nitrogen and mineral source, respectively. The nutrient sources were also found to be very effective for high antifungal activities against R. solani and S. homoeocarpa. It was elucidated that YUD-F group (P. mandelii and P. fluorescens), which inhabit regions at relatively low temperature, had more broad spectrum and higher antifungal activity than YUD-O group (P. trivialis and P. jessenii) generally against R. solani and S. homoeocarpa. It is thought that the differences of the average temperature in the various habitats of Pseudomonas spp. influence the optimal growth temperature and antifungal activity. Especially, Pseudomonas spp. of YUD-O group showed the better antifungal activity against dollar spot caused by S. homoeocarpa, but showed relatively weaker antifungal activity against brown patch caused by R. solani.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.120-124
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• 2007

Fusarium proliferatum KGL0401 was previously isolated from Physalis alkekengi var. francheti plant roots and exhibited higher GA productivity than wild type Gibberella fujikuroi. The :tim of this work was to find out an optimal culture condition for GA production. Various carbon(fructose, glucose, lactose, maltose, sucrose) and nitrogen($KNO_3$, urea, glycine, $NaNO_3,\;NH_4Cl$) sources were used for this study. GAs activities were analysed by gas chromatography and mass spectrometry(GC-MS). The highest yield of $GA_3$ was found in the growth medium supplemented with sucrose as carbon source and $NH_4Cl$ as nitrogen source. The optimum carbon-nitrogen concentration for $GA_3$ production was found to be 0.5 M:0.17 M. Supernatant was prepared from the culture fluid of F. proliferatum KGL0401 cultured for 7 days at 3 0'E and the 10 ul supernatant was treated with 2 leaf-rice seedling.

• Advanced Composite Materials
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• v.17 no.1
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• pp.25-40
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• 2008

The research and development in soundproof materials for preventing noise have attracted great attention due to their social impact. Noise insulation materials are especially important in the field of soundproofing. Since the insulation ability of most materials follows a mass rule, the heavy weight materials like concrete, lead and steel board are mainly used in the current noise insulation materials. To overcome some weak points in these materials, fiber reinforced composite materials with lightweight and other high performance characteristics are now being used. In this paper, innovative insulation sheet materials with carbon and/or glass fabrics and nano-silica hybrid PU resin are developed. The parameters related to sound performance, such as materials and fabric texture in base fabric, hybrid method of resin, size of silica particle and so on, are investigated. At the same time, the wave analysis code (PZFlex) is used to simulate some of experimental results. As a result, it is found that both bundle density and fabric texture in the base fabrics play an important role on the soundproof performance. Compared with the effect of base fabrics, the transmission loss in sheet materials increased more than 10 dB even though the thickness of the sample was only about 0.7 mm. The results show different values of transmission loss factor when the diameters of silica particles in coating materials changed. It is understood that the effect of the soundproof performance is different due to the change of hybrid method and the size of silica particles. Fillers occupying appropriate positions and with optimum size may achieve a better effect in soundproof performance. The effect of the particle content on the soundproof performance is confirmed, but there is a limit for the addition of the fillers. The optimization of silica content for the improvement of the sound insulation effect is important. It is observed that nano-particles will have better effect on the high soundproof performance. The sound insulation effect has been understood through a comparison between the experimental and analytical results. It is confirmed that the time-domain finite wave analysis (PZFlex) is effective for the prediction and design of soundproof performance materials. Both experimental and analytical results indicate that the developed materials have advantages in lightweight, flexibility, other mechanical properties and excellent soundproof performance.

• Journal of Energy Engineering
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• v.25 no.2
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• pp.86-93
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• 2016

The existence of high temperature equipment such as steam pipe, deaerator, steam storage tanks and main steam stop valves makes relatively higher workplace temperature in a power plant of the turbine building. In order to cool down the air temperature in the turbine building, the outside air flow with lower temperature passes through the window and the hotter air in the building is extracted to the outside by installing the ventilation fan on the roof. Nevertheless, higher temperature regions near the high temperature equipment still exist in the turbine building and additional fans for the temperature reduction in the higher temperature region should be examined for the optimal location and mass flow rate. The purpose of the present study is to suggest the optimized location and capacity of the additional ventilation fans for a comfortable working environment. From the present study, it has been elucidated that the additional ventilation fans might be located near the high temperature deaerator and it could reduce the mean temperature in the turbine building by $3.0^{\circ}C$ and the temperature near the deaerator could be reduced by $4.2^{\circ}C$.

• Tunnel and Underground Space
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• v.22 no.4
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• pp.227-242
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• 2012

Youngju multipurpose dam is planned to minimizing the damage by flood and obtaining the water for industrial use in Nakdong river region. Faults in rock mass have strong influences on the behaviors of dam structure. Thus, it is very important to analyse for the characteristics of fault rocks in dam design. However, due to the limitation of geotechnical investigation in design stages, engineers have to carry out the additional geological survey including directional boring to find the distribution of faults and the engineering properties of faults for stability of dam. Especially, the selection of location of dam and type of dam considering fault zone must be analyzed through various experimental and numerical analysis. In this study, various geological survey and field tests were carried out to analyse the characteristics of the large fault zone through the complex dam is designed in foundation region. Also, the distribution of structural geology, the shape of faults and the mechanical properties of fault rock were studied for the reasonable design of the location and type of dam for long-term stability of the complex dam.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.447-451
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• 2019

6-gingerol can be converted to 6-shogaol, one of the predominant active compounds found in ginger, via processing such as drying and extraction. Subcritical water extraction is the environmentally friendly method of extraction of bioactive compounds using only purified water as a solvent. This study investigated subcritical water extraction ($190^{\circ}C$, 15 min) of 6-gingerol, and 6-shogaol from dried ginger (Zingiber officinale) including drying conditions such as temperature (room temperature, 60, $80^{\circ}C$, and freeze drying) and time duration for drying (1-4 h). The amount of 6-gingerol was found to be reduced, and that of 6-shogaol was found to be increased depending upon the water content of dried ginger. Upon oven-drying ginger at $60^{\circ}C$ for 2 h, the maximum yields of 6-gingerol ($0.18{\pm}0.02mg/g$ fresh weight), and 6-shogaol ($0.47{\pm}0.02mg/g$ fresh weight) were obtained upon subcritical water extraction.

• Journal of Life Science
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• v.29 no.10
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• pp.1126-1135
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• 2019

From a sample of bamboo byproduct, the protease-producing yeast strain CO-1 was newly isolated. Strain CO-1 is spherical to ovoid in shape and measures $3.1-4.0{\times}3.8-4.4{\mu}m$. For the growth of strain CO-1, the optimal temperature and initial pH were $30^{\circ}C$ and 4.0, respectively. The strain was able to grow in 0.0-15.0%(w/v) NaCl and 0.0-9.0%(v/v) ethanol. Based on a phylogenetic analysis of its 18S rDNA sequences, strain CO-1 was identified as Pichia anomala. The extracellular protease produced by P. anomala CO-1 was partially purified by ammonium sulfate precipitation, which resulted in a 14.6-fold purification and a yield of 7.2%. The molecular mass of the protease was recorded as approximately 30 kDa via zymogram. The protease activity reached its maximum when 1.0%(w/v) CMC was used as the carbon source, 1.0%(w/v) yeast extract was used as the nitrogen source, and 0.3%(w/v) $MnSO_4$ was used as the mineral source. The protease revealed the highest activity at pH 7.0 and $30^{\circ}C$. This enzyme maintained more than 75% of its stability at a pH range of 4.0-10.0. After heating at $65^{\circ}C$ for 1 hr, the neutral protease registered at 60% of its original activity. The protease production coincided with growth and attained a maximal level during the post-exponential phase.

• Journal of the Korean Geotechnical Society
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• v.37 no.3
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• pp.31-41
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• 2021

A dozer is a construction machinery used to move soil mass along large open tracts of land. Soil thrust generated on the soil-track interface determines the performance of the dozer; to improve the tractive performance of the dozer, the outer surface of the continuous-track is designed to protrude with grousers. In this study, we calculated soil thrust of the dozer equipped with grousers with various shape ratios, and evaluated the optimal grouser shape ratio considering ground conditions. Grouser generated additional soil thrust on the side of the continuous-track (e.g., side soil thrust) and converted the shearing surface (e.g., from soil-track interface to soil-soil interface), increasing the soil thrust of dozer by about 1.3 to 1.6 times. The effect of grouser's shape ratio on the soil thrust of dozer differed with the relative density of the ground. As the shape ratios of grouser increased, soil thrust of dozer decreased at the relative density of 40% and increased at the relative density of 80%. Based on these results, it can be concluded that the shape ratio of grouser severely affects the dozer's performance; thus, careful consideration of the optimal shape ratio of grouser is of great importance in the mechanical design, evaluation, and optimization of the undercarriage of dozers.

• Journal of Microbiology and Biotechnology
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• v.32 no.5
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• pp.630-637
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• 2022

The objective of this study was to optimize industrial-grade media for improving the biomass production of Weissella cibaria JW15 (JW15) using a statistical approach. Eleven variables comprising three carbon sources (glucose, fructose, and sucrose), three nitrogen sources (protease peptone, yeast extract, and soy peptone), and five mineral sources (K₂HPO₄, potassium citrate, ⳑ-cysteine phosphate, MgSO₄, and MnSO₄) were screened by using the Plackett-Burman design. Consequently, glucose, sucrose, and soy peptone were used as significant variables in response surface methodology (RSM). The composition of the optimal medium (OM) was 22.35 g/l glucose, 15.57 g/l sucrose, and 10.05 g/l soy peptone, 2.0 g/l K₂HPO₄, 5.0 g/l sodium acetate, 0.1 g/l MgSO₄·7H₂O, 0.05 g/l MnSO₄·H₂O, and 1.0 g/l Tween 80. The OM significantly improved the biomass production of JW15 over an established commercial medium (MRS). After fermenting OM, the dry cell weight of JW15 was 4.89 g/l, which was comparable to the predicted value (4.77 g/l), and 1.67 times higher than that of the MRS medium (3.02 g/l). Correspondingly, JW15 showed a rapid and increased production of lactic and acetic acid in the OM. To perform a scale-up validation, batch fermentation was executed in a 5-l bioreactor at 37℃ with or without a pH control at 6.0 ± 0.1. The biomass production of JW15 significantly improved (1.98 times higher) under the pH control, and the cost of OM was reduced by two-thirds compared to that in the MRS medium. In conclusion, OM may be utilized for mass producing JW15 for industrial use.