• Journal of the Korean Institute of Gas
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• v.10 no.2 s.31
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• pp.22-26
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• 2006

In this study, modeling and simulation works using Aspen Plus were carried out for DME separation and purification process of pilot plant for the daily production of 50 kg of DME. For modeling of the entire DME separation unit, NRTL liquid activity coefficient model was used for the prediction of liquid phase non-idealities, Henry's law option was also used for the estimation of solubilities of light gases in solvents and SRK equation of state model was utilized for the description of vapor phase non-idealities. DME having over 98 wt% purity was obtained as a side distillate product in a DME purification column.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.1
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• pp.1-7
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• 2023

A fuel handling process combined with a pressure swing adsorption system (PSA) was simulated to produce pure hydrogen with a purity greater than 99.97%. The simulation consists of two parts. The fuel processing part consisting of reformer and water-gas shift reaction was simulated with Aspen plus^®, and the hydrogen purification part consisting of PSA was simulated with Aspen Adsorption^®. In this study, the effect of reformer temperature and pressure on the total hydrogen production yield was investigated. Simulations were performed over a temperature range of 700 to 1,000℃ and a pressure range of 1 to 10 bar. The total hydrogen production yield increased with increasing temperature and decreasing pressure. The maximum hydrogen yield was less than 50% in the simulation and will be lower in the real process.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.2
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• pp.179-185
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• 2006

The Ministry of Agriculture and Forestry announced in 2001 that the overall amount of paddy land set aside for rice will be cut down by 12% by 2005, decreasing from 1.08 million to 953,000 hectares. When evaluating the value of paddy rice systems, the multi-function of paddy systems in the monsoon climate is vital importance. The main functions of paddy rice systems are to conserve biodiversity and maintain sustainability. Some crucial environmental benefits of the paddy rice systems include: flood prevention, recharge of water resources, water purification, soil erosion and landslide prevention, soil purification, landscape preservation and air purification. The paddy rice systems in Korea, which are more diverse than upland crop systems, are known to be composed of 14 orders, 36 families and 134 species. The sustain ability of paddy rice production systems can never be overestimated. Rice is part of the culture and even the heart of spiritual life in the area under the monsoon climate. Therefore paddy rice systems should be preserved with the highest priority being the enhancement of the systems' multi-function. As an outlook to future research, the need of joint and interdisciplinary research projects between economists and natural scientists at inland as well as international levels were emphasized in establishing the development of counter-measure logic through actual proofed analysis.

• YAKHAK HOEJI
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• v.54 no.4
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• pp.316-321
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• 2010

Adefovir dipivoxil which was originally developed by Gilead Sciences has been used as treatments of HIV and HBV, especially a therapeutics for HBeAg positive and negative chronic patients. We developed highly efficient purification method using reverse phase column chromatography for mass production and a stable amorphous Adefovir dipivoxil using solid dispersion method. Reverse phase column chromatography led to highly pure product, more than 99.7% by HPLC and can be used for mass production compared with normal column chromatography. Solid dispersion method containing watersoluble polymer and Isomalt showed improved stability of amorphous Adefovir dipivoxil against heat and moisture.

• Journal of Life Science
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• v.19 no.5
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• pp.561-565
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• 2009

Human Tissue factor is an essential enzyme activator that forms a catalytic complex with factor VII/ VIIa, and catalyzes both the extrinsic and intrinsic blood coagulation cascades. The extracellular domain of human tissue factor is responsible for association with the biological partner. The efficient procedures for preparing biologically active human tissue factor are essential for the preclinical and clinical studies with coaguligands. An expression vector in Escherichia coli has been constructed to direct the production of extracellular human tissue factor without a fusion protein or a $His_6$ at the N-terminus. The recombinant human tissue factor was expressed in large amounts as a non-native state in E. coli. The recombinant protein was simply renatured during the DEAE-sephacel chromatographic purification procedure. Our expression and purification system does not require a protease treatment or an additional chromatographic step to remove a fusion contaminant, which provides a very useful alternative to conventional expression systems for the production of human tissue factor.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.34-38
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• 2003

For the production of $B^{30}-homoserine$ insulin analog as a novel anti-diabetic drug, the fermentative study was attempted for the maximal gene expression of HTS-fused $B^{30}-homoserine$ insulin precursor in the recombinant Escherichia coli cells. In a batch fermentation, the maximal production of insulin precursor as much as 38.95 mg/L-h, which occupied more than 12.8% of total cell protein. was achieved when the gene expression was induced by 0.5 mM IPTG at the middle logarithmic growth phase. The HTS-fused $B^{30}-homoserine$ insulin precursor was recovered from a batch culture through the processes of cell harvest, collection of insoluble fraction after sonication and purification by nickel affinity column chromatography. The isolated insulin precursor was 14 mg/L with a recovery yield of 35.9% of expressed gene product. The insulin A and B chain mixture was recovered after the insulin precursor was subjected to CNBr cleavage and purified by nickel affinity column chromatography. The isolated insulin chains were then sulfitolyzed with sodium thiosulfat and sodium tetrathionate, and reconstituted to insulin analog with ${\beta}-mercaptoethanol$, followed by purification with CM-Sepharose C-25 column chromatography.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.1
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• pp.40-45
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• 2007

Methylene blue(MB) was photocatalytically degraded with one-body photoanode and solar simulator to investigate the possible application to both environmental purification and photoelectrochemical cell for hydrogen production. Photoactive titanium dioxide was formed on both sides of Ti plate following steps such as rinsing-annealing-calcination or anodizing(20 V, 30 V)-annealing($350^{\circ}C$, $450^{\circ}C)$ after etching. The prepared titania plate($2cm{\times}2\;cm$, ca 1.6 mg $TiO_2$ on the basis of $1\;{\mu}m$ thickness) was used to degrade MB(10 ppm in 200 mL solution). The reaction tended to follow the Langmuir-Hinshelwood kinetics with zero order. Comparative experiments with Degussa P25 showed the same zero order kinetics when 2 mg of P25 had been used, while the first order kinetics when 200 mg used. This concludes the feasibility of the prepared titania plate as a material for the purification of low-level harmful organics and an electrode or a membrane for photoelectrochemical system for hydrogen production.

• ALGAE
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• v.25 no.2
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• pp.99-104
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• 2010

A psychrotolerant cyanobacterium, Nodularia spumigena KNUA005, was isolated from a cyanobacterial bloom sample collected near Dasan Station in Ny-${\AA}lesund$, Svalbard Islands during the Arctic summer season. To generate an axenic culture, the isolate was subjected to three purification steps: centrifugation, antibiotic treatment and streaking. The broad antibacterial spectrum of imipenem killed a wide range of heterotrophic bacteria, while the cyanobacterium was capable of enduring both antibiotics, the remaining contaminants that survived after treatment with imipenem were eliminated by the application of an aminoglycoside antibiotic, kanamycin. Physical separation by centrifugation and streaking techniques also aided axenic culture production. According to the cold-tolerance test, this mat-forming cyanobacterium was able to proliferate at low temperatures ranging between 15 and $20^{\circ}C$ which indicates the presence of cold-tolerance related genes in N. spumigena KNUA005. This suggests the possibility of incorporating cold-resistance genes into indigenous cyanobacterial strains for the consistent production of algae-based biofuel during the low-temperature seasons. Therefore, it is needed to determine the cold-tolerance mechanisms in the Arctic cyanobacterium in the next research stage.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.218-223
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• 2011

To obtain eicosapentaenoic acid (EPA)-producing bacteria, some 600 strains of bacteria were isolated from Antarctic sediment and marine organisms during the summer expedition of 1999-2000 and 7 EPA-producing bacteria were obtained through screening with TLC and GC. A strain designated as L93 showed the highest EPA production, which was gram-negative, rod-shaped bacterium. L93 strain was identified as Shewanella sp., from the sequence analysis of 16S rDNA. Optimal conditions temperature and pH for the growth and EPA production were about $4^{\circ}C$ and pH 7. In addition, its production was optimized by 50%(w/v) sea salt. We establish the optimal production system to produce about 320 mg per liter by using this optimal EPA production conditions. EPA-methyl ester was purified from cultured L93 strain to a purity of higher than 97% and typical purification yield is greater than 72% of the input amount via urea complexation and HPLC.

• KSBB Journal
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• v.30 no.3
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• pp.103-108
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• 2015

Production of foreign proteins by transgenic plant cell cultures has several advantages such as post-translational modification, low risk of product contamination and low-cost production and purification. However, target proteins are degraded by extracellular proteases existing in the media. A solution to this problem is the use of perfusion culture and ion exchange chromatography for the application of integrated bioprocess using in situ recovery. With this method, production of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) was investigated in this study. First, optimization of cell concentration during the induction phase for the production of hGM-CSF was examined. As cell concentration increased, the level of hGM-CSF was decreased due to the presence of extracellular proteases. Induction using sugarfree media produced 33% more hGM-CSF. The effects of pH on the binding of hGM-CSF to cationic and anionic exchange resins were also investigated. In terms of stability, optimal pH was found to be 5~7. In the case of using buffer exchange when CM-Sepharose was used as a cationic exchange resin, optimal pH for binding was 4.8 and adsorption yield was 77%. When DEAE-Sepharose was used as an anionic exchange resin, it was 5.5 (74%). Without buffer exchange, optimal pH was 4.6 (84%). From these results, an integrated bioprocess using in situ recovery with simultaneous production and separation of foreign protein in transgenic plant cell suspension cultures was found to be feasible.