• Journal of Microbiology and Biotechnology
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• v.17 no.6
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• pp.1054-1057
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• 2007

Lipases are industrially useful versatile enzymes that catalyze numerous different reactions including hydrolysis of triglycerides, transesterification, and chiral synthesis of esters under natural conditions. Although lipases from various sources have been widely used in industrial applications, such as in food, chemical, pharmaceutical, and detergent industries, there are still substantial current interests in developing new microbial lipases, specifically those functioning in abnormal conditions. We screened 17 lipase-producing yeast strains, which were prescreened for substrate specificity of lipase from more than 500 yeast strains from the Agricultural Research Service Culture Collection (Peoria, IL, U.S.A.), and selected Yarrowia lipolytica NRRL Y-2178 as a best lipase producer. This report presents new finding and optimal production of a novel extracellular alkaline lipase from Y. lipolytica NRRL Y-2178. Optimal culture conditions for lipase production by Y. lipolytica NRRL Y-2178 were 72 h incubation time, $27.5^{\circ}C$, pH 9.0. Glycerol and glucose were efficiently used as the most efficient carbon sources, and a combination of yeast extract and peptone was a good nitrogen source for lipase production by Y. lipolytica NRRL Y-2178. These results suggested that Y. lipolytica NRRL Y-2178 shows good industrial potential as a new alkaline lipase producer.

• Applied Biological Chemistry
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• v.27 no.4
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• pp.238-244
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• 1984

To produce inulase from Kluyveromyces fragilis No.351 using Jerusalem artichoke tuber extract, optimization of the condition was conducted. As results, the optimal concentration of artichoke tuber extract was 3.5 % and bactocasitone showed better production than yeast extract. The optimal temperature and pH were $30^{\circ}C$ and 5.5, respectively. The addition of $NH_4H_2PO_4$ increased the enzyme production. Inulase synthesis was growth-associated and the enzyme production increased as concentration of dissolved oxygen increased. A higher quantity of industrial grade inulase was prepared by the combination of ultrafiltration and ethanol precipitation with 72% recovery.

• Membrane and Water Treatment
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• v.8 no.3
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• pp.279-292
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• 2017

This study was aimed at ultrafiltration (UF) as a pretreatment before reverse osmosis (RO) within the scheme of hybrid reverse osmosis-multistage flush (RO-MSF) desalination. Seawater at elevated temperature (after MSF heat-exchangers) was used as a feed in this process. The pretreatment system was represented as a set of functionally-linked technological segments such as: UF filtration, backwashing, chemical- enhanced backwashing, cleaning, waste disposal, etc. The process represents the sequences of operating cycles. The cycle, in turn, consists of the following unit operations: filtration, backwashing and chemical-enhanced backwashing (CEB). Quantitative assessment was based on the following indicators: normalized permeability, transmembrane pressure, specific energy and water consumption, specific waste generation. UF pre-treatment is accompanied by the following waste streams: $W1=1.19{\times}10$ power of $-2m^3$ (disposed NaOCl with 0.0044% wt.)/$m^3$ (filtrate); $W2=5.95{\times}10$ power of $-3m^3$ (disposed $H_2SO_4$ with 0.052% wt.)/$m^3$(filtrate); $W3=7.26{\times}10$ power of $-2m^3$ (disposed sea water)/$m^3$ (filtrate). Specific energy consumption is $1.11{\times}10$ power of $-1kWh/m^3$ (filtrate). The indicators evaluated over the cycles with conventional (non-chemical) backwashing were compared with the cycles accompanied by CEB. A positive impact of CEB on performance indicators was demonstrated namely: normalized UF resistance remains unchanged within the regime accompanied by CEB, whereas the lack of CEB results in 30% of its growth. Those quantitative indicators can be incorporated into the target function for solving different optimization problems. They can be used in the software for optimisation of operating regimes or in the synthesis of optimal flow- diagram. The cycle characteristics, process parameters and water quality data are attached.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.1977-1988
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• 2015

β-1,3-glucanosyltransferases play essential roles in cell wall biosynthesis in yeast. Kluyveromyces lactis has six putative β-1,3-glucanosyltransferase genes. KlGAS1-1 and KlGAS1-2 are homologs of Saccharomyces cerevisiae gene GAS1. RT-qPCR indicated the transcription level of KlGAS1-1 was significantly reduced while heterologous protein (thermostable xylanase B) secretion was enhanced during medium optimization. To evaluate if these two events were related, and to improve xylanase B secretion in K. lactis, we constructed KlGAS1-1 and KlGAS1-2 single deletion strains and double deletion strain, respectively. KlGAS1-1 gene deletion resulted in the highest xylanase B activity among the three mutants. Only the double deletion strain showed morphology similar to that of the GAS1 deletion mutant in S. cerevisiae. The two single deletion strains differed in terms of cell wall thickness and xylanase B secretion. Transcription levels of β-1,3-glucanosyltransferase genes and genes related to protein secretion and transport were assayed. The β-1,3-glucanosyltransferase genes displayed transcription complementation in the cell wall synthesis process. KlGAS1-1 and KlGAS1-2 affected transcription levels of secretion- and transport-related genes. Differences in protein secretion ratio among the three deletion strains were associated with changes of transcription levels of secretion- and transport-related genes. Our findings indicate that KlGAS1-1 deletion is an effective tool for enhancing industrial-scale heterologous protein secretion in K. lactis.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1108-1113
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• 2015

Cadaverine (1,5-diaminopentane) is an important industrial chemical with a wide range of applications. Although there have been many efforts to produce cadaverine through fermentation, there are not many reports of the direct cadaverine production from lysine using biotransformation. Whole-cell reactions were examined using a recombinant Escherichia coli strain overexpressing the E. coli MG1655 cadA gene, and various parameters were investigated for the whole-cell bioconversion of lysine to cadaverine. A high concentration of lysine resulted in the synthesis of pyridoxal-5'-phosphate (PLP) and it was found to be a critical control factor for the biotransformation of lysine to cadaverine. When 0.025 mM PLP and 1.75 M lysine in 500 mM sodium acetate buffer (pH6) were used, consumption of 91% lysine and conversion of about 80% lysine to cadaverine were successfully achieved.

• Journal of Korea Multimedia Society
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• v.13 no.7
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• pp.943-949
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• 2010

This paper presents some improvements on VLSI implementation of lifting-based 9/7 wavelet transform by optimization hardware multiplication. The proposed solution requires less logic area and power consumption without performance loss compared to previous wavelet filter structure based on lifting scheme. This paper proposes a better approach to the hardware implementation using Lefevre algorithm based on extensions of Pattern search methods. To compare the proposed structure to the previous solutions on full multiplier blocks, we implemented them using Verilog HDL. For a hardware implementation of the two solutions, the logical synthesis on 0.18 um standard cells technology show that area, maximum delay and power consumption of the proposed architecture can be reduced up to 51%, 43% and 30%, respectively, compared to previous solutions for a 200 MHz target clock frequency. Our evaluation show that when design VLSI chip of lifting-based 9/7 wavelet filter, our solution is better suited for standard-cell application-specific integrated circuits than prior works on complete multiplier blocks.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.7
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• pp.50-57
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• 2000

We propose a logic synthesis algorithm for the design of FPGAs operating at high speed. FPGA is a novel technology that provides programmability in the field. Because of short turnaround time and low manufacturing cost, FPGA has been noticed as an ideal device for system prototyping. Despite these merits, FPGA has drawbacks, namely low integration and long delay time comparing to ASIC. The proposed algorithm partitions a given circuit into subcircuits utilizing a kernel divisor such that the subcircuits can be performed at the same time, hence reducing the delay of the circuit. Experimental results on the MCNC benchmark show that the proposed algorithm is effective by generating circuits having 19.1% les delay on average, when compared to the FlowMap algorithm.

• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.655-664
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• 2020

Free viewpoint image synthesis technology is one of the important technologies in the MPEG-I (Immersive) standard. RVS (Reference View Synthesizer) developed by MPEG-I and in use in MPEG group is a DIBR (Depth Information-Based Rendering) program that generates an image at a virtual (intermediate) viewpoint from multiple viewpoints' inputs. RVS uses the mesh surface method based on computer graphics, and outperforms the pixel-based ones by 2.5dB or more compared to the previous pixel method. Even though its OpenGL version provides 10 times speed up over the non OpenGL based one, it still shows a non-real-time processing speed, i.e., 0.75 fps on the two 2k resolution input images. In this paper, we analyze the internal of RVS implementation and modify its structure, achieving 34 times speed up, therefore, real-time performance (22-26 fps), through the 3 key improvements: 1) the reuse of OpenGL buffers and texture objects 2) the parallelization of file I/O and OpenGL execution 3) the parallelization of GPU shader program and buffer transfer.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.266-272
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• 2020

In this study, the production of ethyl levulinate from chitosan using successive acid-catalyzed hydrolysis and esterification was investigated. To optimize and analysis the reaction factors and heir reciprocal interaction, response surface methodology was introduced. In the effect of water content in ethanol solvent, the production yield of ethyl levulinate was high at 5% water content (or 95% ethanol). As a result of optimization of reaction factors, 30.1% ethyl levulinate yield was obtained under the condition of 200 ℃, 3.19% chitosan, 0.49M sulfuric acid, 5% water content, and 58 min. Finally, the formation yield of ethyl levulinate was tended to enhance by increase of combined severity factor. This result indicated that the potential of chitosan as feedstock for production of chemicals and fuels.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.394-398
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• 2012

Astragalin (AS), kaempferol monoglycoside, is classified as a polyphenol, and a minute quantity of AS is known to be present in several plants. Recently, it was reported that AS can be prepared by the partial hydrolysis of camelliaside A (CamA) and camelliaside B (CamB) in the tea seed extract (TSE) in the presence of a commercial enzyme complex such as Mash. In this paper, the effects of reaction temperature, amount of enzyme, and the substrate concentration on the reactivity were investigated. As the reaction temperature or the amount of enzyme increased, the reaction rate to produce AS increased, however, the hydrolysis of AS into KR was also enhanced. As a conclusion, the reaction, when 2 mL of Mash to 1 g of TSE was applied with a substrate concentration of 15% at $50^{\circ}C$, was found to be optimum, based on the reaction rate and the selectivity to AS.