• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.45-51
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• 2004

Initial flame development and propagation were visualized under different fuel injection timings to relate the initial flame development to the engine stability in a port injection SI engine. Experiments were performed in an optical single cylinder engine modified from a production engine and images were captured through the quartz window mounted in the piston by an intensified CCD camera. Stratification state was controlled by varying injection timing. Under each injection condition, the flame images were captured at the pre-set crank angles. These were averaged and processed to characterize the flame. The flame stability was estimated by the weighted average of flame area, luminosity, and standard deviation of flame area. Results show that stratification state according to injection timing did not affect on the direction of flame propagation. The flame development and the initial flame stability are strongly dependent on the stratified conditions and the initial flame stability governs the engine stability and lean misfire limit.

• Journal of the Korean Applied Science and Technology
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• v.12 no.1
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• pp.1-11
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• 1995

In this outline, the stability of solid/liquid dispersion was theoretically investigated the matter from all angles by using the modified DLVO theory. The stability was handled various considerations such as a production and characteristics of electrical double layer, total interaction$(V_T)$ that consisting of attractive force$(V_A)$ and repulsion$(V_R)$. coagulation, the stability ratio(W), critical flocculation concentration (cfc) and zeta potential$(\zeta)$ etc. It was possible for us to examine with the stability ratio(W), critical flocculation concentration (cfc) and zeta potential$(\zeta)$ that may estimation of stability of solid/liquid dispersion experimentally.

• Journal of the Korean Wood Science and Technology
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• v.30 no.3
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• pp.85-90
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• 2002

This study was carried out to investigate the dimensional stability of bentwoods by three treatments: steaming, urethane varnish coating, and polyethylene glycol (PEG) treatment. Bentwood processing employed a bending-jig with only 4 cm radius of curvature (ROC). The used species were bitter wood (Picrasma quassioides), painted maple (Acer mono), and birch (Betula schmidtiii). The bending properties of these are well-known in bentwood production (Jung et al., 2002). The bentwoods were treated repeated at room temperature [20℃, RH 80% (12 hours) and 40℃ under RH 10% (12 hours)]. To estimate the dimensional stability of bentwoods, we measured the radius of curvature and end-distance. The best results could be attained with PEG treatment. Steaming was the worst treatment. Comparing the properties of the different species, the dimensional stability of bitter wood was excellent. It was concluded that the steaming treatment was unsuitable for dimensional stability of bentwoods.

• Advances in nano research
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• v.13 no.2
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• pp.135-146
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• 2022

The accurate assessment of the performance of nonuniform systems requires a thorough understanding of stability analysis. As a result, the theoretical modeling of the influence of various variables on the performance of small-scale nonuniform structures with conventional and non-conventional geometries is presented in this paper. According to the fundamental computer simulation based on mathematical and mechanical principles, the stability of the nonuniform structures is examined. Thus, a numerical procedure is used to simulate the stability and instability characteristics of the nonuniform small-scale structures via computer aid. Theoretic simulation methods provide a great deal of the design and production of small-scale structures at a low cost compared to experimental simulations. Thus, this paper provides a good presentation of the stability analysis of the nonuniform nanoscale structures with high accuracy without actual experimental.

• Journal of Microbiology and Biotechnology
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• v.1 no.2
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• pp.116-120
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• 1991

The transformant Bacillus subtilis ED213 carrying the pSO100 which cloned the cdd gene encoding cytidine deaminase (cytidine /2'-deoxycytidine aminohydrolase, EC 3.5.4.5, CDase) originated from wild type B. subtilis was cultivated in Spizizen minimal medium (SMM). To overcome poor expression of the cdd gene in SMM medium, the medium compositions and growth conditions were optimized. The optimized medium compositions and growth conditions were cytidine concentration of 80 mg/l, glycerol of 25 g/l, and $(NH_4)_2SO_4$ of 10 g/l, along with $37^{\circ}C$ and pH 7.0. The intracellular CDase production was increased 3 times from 1,000 unit/ml to 3,200 unit/ml, and extracellular CDase also increased from nearly undetectable amounts to 1,500 unit/ml. The cytidine concentration was signified as the most critical compositional factor for overproduction of CDase by increasing the cell density mainly in culture broth. The plasmids were more stable in cells that were grown in original SMM medium with stability of 90% compared to those grown in optimized SMM medium with stability of 80% after 48 hours cultivation. The most active amplification of plasmid was occurred in the logarithmic phase, which showed a value around four times higher than the initial copy number. In the exponential phase, the CDase production was closely related to the plasmid copy number along with the cell density. However, it was not accorded with cell density at the stationary phase.

• KSBB Journal
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• v.7 no.4
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• pp.284-289
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• 1992

The optimum conditions for the production of tryptophan using a recombinant Klebsiella pnuemoniae phe A tyr A trp R/pSC 101-$trp^{+}$ and its plasmid stability during tryptophan production were studied. The optimum temperature was $37^{\circ}C$ and the specific growth rate was 1.05$h^{-1}$ at $37^{\circ}C$. Tryptophan production was increased by glucose fed-batch culture, and tryptophan was accumulated to 0.175 g/l after 36 hrs. This amount was about 1.2 and 1.6 times greater than that obtained from batch culture and flask culture, respectively. The stability of the strain in fed-batch cu1ture was greatly different from that in repeated flask culture. After 6 generation, 95% of total cells was stable in repeated flash culture, but in fed-batch culture only 50% was stable.

• Journal of Microbiology and Biotechnology
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• v.21 no.11
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• pp.1159-1165
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• 2011

Biodiesel is methyl and ethyl esters of long-chain fatty acids produced from vegetable oils or animal fats. Lipase enzymes have occasionally been used for the production of this biofuel. Recently, biodiesel production using immobilized lipase has received increased attention. Through enhanced stability and reusability, immobilized lipase can contribute to the reduction of the costs inherent to biodiesel production. In this study, methanol-tolerant lipase M37 from Photobacterium lipolyticum was immobilized using the cross-linked enzyme aggregate (CLEA) method. Lipase M37 has a high lysine content (9.7%) in its protein sequence. Most lysine residues are located evenly over the surface of the protein, except for the lid structure region, which makes the CLEA preparation yield quite high (~93%). CLEA M37 evidences an optimal temperature of $30^{\circ}C$, and an optimal pH of 9-10. It was stable up to $50^{\circ}C$ and in a pH range of 4.0-11.0. Both soluble M37 and CLEA M37 were stable in the presence of high concentrations of methanol, ethanol, 1-propanol, and n-butanol. That is, their activities were maintained at solvent concentrations above 10% (v/v). CLEA M37 could produce biodiesel from olive oil and alcohols such as methanol and ethanol. Additionally, CLEA M37 generated biodiesel via both 2-step methanol feeding procedures. Considering its physical stability and reusability, CLEA M37 may potentially be used as a catalyst in organic synthesis, including the biodiesel production reaction.

• Journal of Aerospace System Engineering
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• v.11 no.4
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• pp.8-14
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• 2017

In this study, the production of proper emulsion fuel and the evaluation of its rheological stability in various experimental conditions were carried out. The W/O (water-in-oil) emulsion fuel was made using n-decane, pure water, and Span 80 was used as a surfactant. Increments of water volume ratio and fuel temperature were the factors, which boosted the phase separation of the emulsion fuel. Rheological characteristics for different water/oil volume ratio, temperature, and elapsed time after the fuel production were examined. As the water volume ratio in the fuel increased, the behavior of non-Newtonian fluid was observed. Viscosity declined as the fuel temperature increased due to the cohesion of water droplets in the fuel. The effect of elapsed time on viscosity was not severe for lower water ratio. However, gradual decrease of viscosity 3 hours after fuel production, in the case of ratio of 3:7, was clearly observed.

• Advances in nano research
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• v.14 no.2
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• pp.165-177
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• 2023

Nanomotors are gaining popularity as novel drug delivery methods since they can move rapidly, penetrate deeply into tissues, and be regulated. The ability of manufactured nanomotors to swiftly transport therapeutic payloads to their intended location constitutes a revolutionary nanomedicine strategy. The nanomotors for the drug delivery purpose are released in the blood flow under the different physical conditions, so the stability investigation of these devices is essential before the production, especially in the sport and physical exercise conditions that the blood flow enhances. As a result, using dynamic analysis, this article investigates the stability of the nanomotor released in the blood flow when sport and physical activity circumstances increase blood flow. The considered nanodevice is made of a central motor, and nanotubes are used for the nanomotor blade, which is the drug capsule. Finally, the stability examination of nanomotor as the drug delivery equipment is discussed in detail, and the proposed results can present beneficial results in designing and producing small-scale intelligent devices.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.4
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• pp.247-253
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• 2014

In the silage quality, the process of fermentation and use of micro-organism as starter cultures are crucial. The present study investigated the effect of homo and heterofermentative lactic acid bacteria as a starter culture strain on the silage quality and its aerobic stability using meta-analysis. Total 19 studies were used in the analysis. According to the strains of lactic acid bacteria used, experimental groups were assigned to heterofermentative (HEL), mixture of hetero and homofermentative (HHO), homofermentative (HOL) and various homofermentative (HOM). In each experimental group, standardized result of the treatment (with inoculant) was compared with the control (without inoculant) using risk ratio calculation method. The effect of experimental group was also compared. Different starter culture strains did not influence on silage pH and propionic acid production. However, lactic acid and acetic acid production were significantly (p<0.05) influenced by the start culture strains. HOM showed the greatest lactic acid production and HEL was the lowest. In contrast, HEL showed the greatest in acetic acid production and HOM and HOL were the lowest. In terms of ammonia nitrogen, HHO produced more (p<0.05) than the rest of the treatment. In crude protein and water soluble carbohydrate contents, there were no significant effects among treatments. Different strain of lactic acid bacteria significantly influenced on the effect of aerobic stability (p<0.05). Use of heterofermentative showed greater aerobic stability and the use of homofermentative lactic acid bacteria.