• Clean Technology
• /
• v.22 no.3
• /
• pp.196-202
• /
• 2016

In this study, ceria- based catalysts were prepared for dimethyl carbonate (DMC) synthesis and reaction conditions were evaluated for finding the optimal reaction route. In order to find optimal catalysts for DMC synthesis, calcination temperature and Cu(II) impregnation amount were evaluated. The oxidative carbonylation using methanol, carbon monoxide and oxygen and the direct synthesis using methanol and carbon dioxide were introduced for producing DMC. Following the law of Le Chatelier, the dehydration reaction was applied for enhancing the reactivity (methanol conversion) as removing water during the reaction. 2-cyanopyridine, as a chemical dehydration agent, was used. In the case of the oxidative carbonylation, methanol conversion rate increased from 15.1% to 38.7% and the DMC selectivity increased from 0% to 98.8%. In the case of the direct synthesis, methanol conversion rate increased from 1.0% to 77.8% and the DMC selectivity increased from 41.2% to 100.0%.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.11
• /
• pp.1151-1158
• /
• 2011

In this study, a galactooligosaccharide (GOS) was synthesized using active ${\beta}$-galactosidase (${\beta}$-gal) inclusion bodies (IBs)-containing Escherichia coli (E. coli) cells. Analysis by MALDI-TOF (matrix-assisted laser desorption/ionization-time of flight) mass spectrometry revealed that a trisaccharide was the major constituent of the synthesized GOS mixture. Additionally, the optimal pH, lactose concentration, amounts of E. coli ${\beta}$-gal IBs, and temperature for GOS synthesis were 7.5, 500 g/l, 3.2 U/ml, and $37^{\circ}C$, respectively. The total GOS yield from 500 g/l of lactose under these optimal conditions was about 32%, which corresponded to 160.4 g/l of GOS. Western blot analyses revealed that ${\beta}$-gal IBs were gradually destroyed during the reaction. In addition, when both the reaction mixture and E. coli ${\beta}$-gal hydrolysate were analyzed by high-performance thin-layer chromatography (HP-TLC), the trisaccharide was determined to be galactosyl lactose, indicating that a galactose moiety was most likely transferred to a lactose molecule during GOS synthesis. This GOS synthesis system might be useful for the synthesis of galactosylated drugs, which have recently received significant attention owing to the ability of the galactose molecules to improve the drugs solubility while decreasing their toxicity. ${\beta}$-Gal IB utilization is potentially a more convenient and economic approach to enzymatic GOS synthesis, since no enzyme purification steps after the transgalactosylation reaction would be required.

• Proceedings of the PSK Conference
• /
• 2000.10a
• /
• pp.212.2-213
• /
• 2000

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2003.05a
• /
• pp.529-536
• /
• 2003

The majority of previous studios on tolerance synthesis have viewed the issue as a design methodology to determine optimal component tolerances on behalf of a manufacturer. while meeting given assembly tolerance requirements Although a considerable amount of research has been done on this issue. a couple of important questions still remain unanswered First. how ran a design engineer quantitatively incorporate a customer's perception on a product quality into a tolerance synthesis scheme at the early design stage Second. how ran component tolerances and assembly tolerance be optimized in a simultaneous way? To answer these questions. this article presents the customer-driven concurrent tolerance synthesis which is facilitated by the notion of truncated distribution and the use of mathematical programming techniques. while adopting the major principles of Tagurhl philosophy. The work presented in the article is an effort to gain insight, which can be useful in practice when setting up guidelines for an overall tolerance synthesis.

• International Journal of Aeronautical and Space Sciences
• /
• v.7 no.1
• /
• pp.129-136
• /
• 2006

A new guidance synthesis for anti-ship missiles to control impact angle and impact time is proposed in this paper. The flight vehicle is assumed as a 1st order lag system to consider more practical system. The proposed guidance synthesis enhances the survivability of anti-ship missiles because multiple anti-ship missiles with the proposed synthesis can hit the target simultaneously. The control input to satisfy constraints of zero miss distance and impact angle, and the feedforward bias control input to control impact time constitute the guidance law. The former is from trajectory shaping guidance, the latter is from neural network. And particle swarm optimization method is introduced to furnish reference input and output for learning in neural network. The performance of the proposed synthesis in the accuracy of impact time and angle is validated by numerical examples.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.9
• /
• pp.1493-1498
• /
• 2007

In this work, alkyl methacrylate-based microgels were synthesized by an experimental design method, and their sebum absorption characteristics were investigated. The results of fractional factorial experimentation indicated that the cross-linking agent content, solvent content, and stirring speed were the main parameters in the synthesis of the microgels. The suitable synthesis conditions were determined by the response surface design method. Through a study of the monomer and solvent effects, it was confirmed that the microgel shows the highest sebum absorption ratio when t-butyl methacrylate is used as a monomer or when acetone is used as a solvent. The optimal microgel synthesis conditions for cosmetic application were determined, and the resulting microgel had a mean particle size of 4.7 μm and a sebum absorption ratio of 435%.

• Journal of Plant Biology
• /
• v.36 no.1
• /
• pp.19-27
• /
• 1993

Effects of polyamines on DNA synthesis were studied in synchronized culture of Nicotiana tabacum L. When DFMO and DFMA, inhibitors of ornithine decarboxylase and arginine decarboxylase, respectively were initially applied to the cells, the polyamine contents were rapidly dropped and [methyl-3H] thymidine incorporation into DNA was markedly reduced during the early stage of culture period. Inhibition of DNA synthesis, however, was partially reversed when these inhibitors were applied simultaneously with putrescine. In addition, exogenous administration of putrescine also increased the DNA synthesis during the all over the culture period. In vitro activity of DNA polymerase from Nicotiana tabacum L. was promoted by increasing concentrations of polyamines in the reaction mixture. Maximal activity was shown at 5 mM putrscine, 0.5 mM spermidine and spermine, respectively. Lack of Mg2+ ion in the reaction buffer resulted in an inhibition of the enzyme activity by about 30%. The inhibition could not be completely reversed by application of polyamines at optimal concentrations. These results suggest that polyamines promote the DNA synthesis in vivo and in vitro by stabilizing the DNA-helix upon binding to negatively charged groups on DNA or increasing the activity of DNA polymerase in Nicotiana tabacum L.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.5
• /
• pp.885-888
• /
• 2008

In this work, we demonstrate that glycolytic intermediates can serve as efficient energy sources to regenerate ATP during continuous-exchange cell-free (CECF) protein synthesis reactions. Through the use of an optimal energy source, approximately 10 mg/ml of protein was generated from a CECF protein synthesis reaction at greatly reduced reagent costs. Compared with the conventional reactions utilizing phosphoenol pyruvate as an energy source, the described method yields 10-fold higher productivity per unit reagent cost, making the techniques of CECF protein synthesis a more realistic alternative for rapid protein production.

• ETRI Journal
• /
• v.41 no.5
• /
• pp.619-625
• /
• 2019

In this paper, we propose an array pattern synthesis scheme using semidefinite programming (SDP) under array excitation power constraints. When an array pattern synthesis problem is formulated as an SDP problem, it is known that an additional rank-one constraint is generated inevitably and relaxed via semidefinite relaxation. If the solution to the relaxed SDP problem is not of rank one, then conventional SDP-based array pattern synthesis approaches fail to obtain optimal solutions because the additional rank-one constraint is not handled appropriately. To overcome this drawback, we adopted a bisection technique combined with a penalty function method. Numerical applications are presented to demonstrate the validity of the proposed scheme.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.10
• /
• pp.1471-1478
• /
• 1989

The optimal-time control of the coordinated motion of two robot manipulators may be of consequence in the industrial automation. In this paper two robot manipulators garsping a common object are assumed to travel a specified Cartesian path and the method how to derive the optimal-time solution is explained. This approach is based on parameterizing the corresponding patn and utilizing the phase-plame technique in the trajectory planning. Also the torques supplied by the actuators are assumed to have some constant bounds. The effectiveness of this approach is demonstrated by a computer simulation using a PUMA 560 manipulator.