• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.137-142
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• 2013

The indiscriminate use of the fossil fuel has caused serious environmental pollutions such as the shortage of energy and global warming. Microalgae have being emphasized as $3^{rd}$ generation biomass which makes the carbon dioxide reduce effectively as well as produces the biofuel. Large scale production of microbial biomass by continuous culture is a quite challenging issue, because off-line optimization strategies of a microbial process utilizing a model-based scheme give rise to many difficult problems. In this paper, the static and simple control method which was able to be applied in time-variant growth environment and large scale of algae culture was studied. The significant disturbances in on-line measurement of cell density were reduced by Savitzky-Golay FIR smoothing filter. Dunaliella salina was cultivated continuously in a flat panel photobioreactor by the on-off control of the turbidostat process.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.285-290
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• 2013

Recently a novel bio refinery process with using nonedible biomass, especially microalgae, has been developed in order to directly reduce $CO_2$ concentration from flue gas and simultaneously produce renewable bio fuel. Micro algae-to-biofuel processes are composed of microalgae cultivation, harvesting, lipid extraction, and bio fuel conversion. So, there are concerns about the energy efficiencies of bio refinery processes. In this study, the net energy ratio of microalgae processes were calculated for the microalgae produced from a pilot photobioreacto using $CO_2$ released from coal combustion. In this study, trans-esterification and pyrolysis processes were used to analyze the net energy efficiencies. Micro algae-to-biofuel processes might produce bio fuels with the higher energy than that of the total consumed energy for cultivation, harvesting, extraction and conversion. If the lipid content of microalgae was higher, the trans-esterification conversion process was more effective than that of pyrolysis process.

• Journal of Microbiology and Biotechnology
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• v.28 no.10
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• pp.1671-1682
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• 2018

Alginate lyases (endo and exo-lyases) are required for the degradation of alginate into its constituting monomers. Efficient bioethanol production and extraction of bioactives from brown algae requires intensive use of these enzymes. Nonetheless, there are few commercial alginate lyase preparations, and their costs make them unsuitable for large scale experiments. A recombinant expression protocol has been developed in this study for producing seven endo-lyases and three exo-lyases as soluble and highly active preparations. Saccharification of alginate using 21 different endo/exo-lyase combinations shows that there is complementary enzymatic activity between some of the endo/exo pairs. This is probably due to favorable matching of their substrate biases for the different glycosidic bonds in the alginate molecule. Therefore, selection of enzymes for the best saccharification results for a given biomass should be based on screens comprising both types of lyases. Additionally, different incubation temperatures, enzyme load ratios, and enzyme loading strategies were assessed using the best four enzyme combinations for treating Macrocystis pyrifera biomass. It was shown that $30^{\circ}C$ with a 1:3 endo/exo loading ratio was suitable for all four combinations. Moreover, simultaneous loading of endo-and exo-lyases at the beginning of the reaction allowed maximum alginate saccharification in half the time than when the exo-lyases were added sequentially.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.189-199
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• 2019

This study addresses the biorefinery feedstock from Pinus densiflora. This raw material is a major tree species in the Republic of Korea; it is renewable, has cost-effective, and is readily available. In this study, steam explosion of P. densiflora was performed in a reactor at $225^{\circ}C$ and with 1 to 13 min reaction times with or without previous water impregnation. The combined severity factor (Ro), which is an expression relating the reaction temperature and reaction time used in the steam explosion treatment, ranged from 3.68 to 4.79. The influence of both impregnation and steam explosion conditions were investigated by examining color variations, chemical composition, and mass balance on the pretreated solids. The results showed that steam-exploded P. densiflora that was not impregnated with water exhibited significantly darker color (chroma 28.8-41.4) than water-impregnated and steam-exploded P. densiflora (chroma 18.8-37.3). The increased ${\alpha}$-cellulose and lignin contents were detected as the severity factor increased. Furthermore, the ${\alpha}$-cellulose and lignin contents in the non-impregnated/steam-exploded P. densiflora were higher than those in the water-impregnated/steam-exploded P. densiflora. However, the decreased holocellulose content was detected as the severity factor increased. In mass balance, the holocellulose yield from water-impregnated/steam-exploded P. densiflora was higher than that from the non-impregnated P. densiflora.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.335-338
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• 2010

In this study, the atmospheric plasma treatment with $He/O_2$ was conducted to modify the surface chemistry of carbon fibers. The effects of plasma treatment parameters on the surface energetics of carbon fibers were experimentally investigated with respect to gas flow ratio, power intensity, and treatment time. Surface characteristics of the carbon fibers were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Fourier transform infrared (FT-IR), Zeta-potential, and contact angle measurements. The results indicated that oxygen plasma treatment led to a large amount of reactive functional groups onto the fiber surface, and these groups can form together as physical intermolecular bonding to improve the surface wettability with a hydrophilic polymer matrix.

• Journal of Integrative Natural Science
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• v.3 no.3
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• pp.148-152
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• 2010

Photoluminescence properties and surface morphologies of porous silicon etched with various applied current densities at fixed etching times. FE-SEM image of porous silicon surface indicated that the porous silicon prepared at currents below 200 mA exhibited very bright red photoluminescence properties. As the applied current densities increased, the photoluminescence efficiencies of porous silicon prepared at applied current densities above 300 mA decreased, and displayed the cracked surface on porous silicon. This cracked surface start to collapsed to give cracked domains.

• BMB Reports
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• v.45 no.1
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• pp.14-19
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• 2012

A feruloyl esterase encoding gene (designated fae6), derived from a leachate metagenomic library, was cloned and the nucleotide sequence of the insert DNA determined. Translational analysis revealed that fae6 consists of a 515 amino acid poly-peptide, encoding a 55 kDa pre-protein. The Fae6 primary structure contained the G-E-S-A-G sequence, which corresponds well with a typical catalytic serine sequence motif (G-x-S-x-G). The fae6 gene was successfully over-expressed in E. coli and the recombinant protein was purified to 8.4 fold enrichment with 17% recovery. The $K_M$ data showed Fae6 has a high affinity to methyl sinapate while thermostability data indicated that fae6 was thermolabile with a half life ($T_{1/2}$) < 30 min at $50^{\circ}C$. High affinity for Fae6 against methyl sinapate, methyl ferulate and ethyl ferulate suggest that the enzyme can be useful in hydrolyzing ferulated polysaccharides in a biorefinery process.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.43-47
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• 2011

In woody waste separated from municipal solid waste, medium density fiberboard was major contributors with particleboard, paper, plywood and log, with different composition based on collected period. In chemical compositional analysis of woody waste, it was similar to softwood based on carbohydrate composition analysis. Based on the carbohydrate composition, saccharified solution from MWW could be good resource for biorefinery.

• Proceedings of the Membrane Society of Korea Conference
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• 2008.05a
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• pp.90-93
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• 2008

• Proceedings of the Membrane Society of Korea Conference
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• 2008.05a
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• pp.180-184
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• 2008