• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.449-455
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• 1994

In order to obtain the basic data for synthetic studies of bioactive peptide using enzyme, Kyotorphin(analgesic peptide) derivative was synthesized from Ac-Tyr-OH and $Arg-NH_2$ by $\alpha-chymotrysin$ in two phase system(organic phase and aqueous phase). In effect of organic solvent on Kyotorphin derivative synthesis from Ac-Tyr-OH(10 mM) and $Arg-NH_2$ (20 mM), the synthesis in ethyl acetate system of organic solvents was higher than those in other organic solvents (n-butanol, n-hexane, dichloromethane and chloroform). The optimal conditions for the synthesis are as follows: enzyme conc., 10 ${\mu}M;$ reaction pH, 7.0; reaction temp., $35^{\circ}C$ ; the ratio of organic phase volume/aqueous phase volume $(\alpha)$, 15. Under the optimal conditions, the yield was 70.2%, and the reaction achieved to equilibrium after 24 hrs.

• Korean Journal of Materials Research
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• v.18 no.5
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• pp.266-271
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• 2008

Magnesium alloys are alloyed with rare earth elements (Re, Ca, Sr) due to the limited use of magnesium in high-temperature conditions. In this study, the influences of Zr and Zn on the aging behavior of a Mg-Nd-Y alloy were investigated. magnesium alloys containing R.E elements require aging treatments Specifically, Nd, Y and Zr are commonly used for high-temperature magnesium alloys. Various aging treatments were conducted at temperatures of 200, 250 and $300^{\circ}C$ for 0.5, 1, 3, 6, and 10 hours in order to examine the microstructural changes and mechanical properties at a high temperature ($150^{\circ}C$). Hardness and high-temperature ($150^{\circ}C$) tensile tests were carried out under various aging conditions in order to investigate the effects of an aging treatment on the mechanical properties of a Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy. The maximum hardness was 67Hv; this was achieved after aging at $250^{\circ}C$ for 3 hours. The maximum tensile, yield strength and elongation at $150^{\circ}C$ were 237MPa, 145MPa and 13.6%, respectively, at $250^{\circ}C$ for 3 hours. The strengths of the Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy increased as the aging time increased to 3 hours at $250^{\circ}C$ This is attributed to the precipitation of a Nd-rich phase, a Zr-rich phase and $Mg_3Y_2Zn_3$.

• Korean Journal of Materials Research
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• v.24 no.8
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• pp.429-433
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• 2014

As the fabrication technology used in FPDs(flat-panel displays) advances, the size of these panels is increasing and the pattern size is decreasing to the um range. Accordingly, a cleaning process during the FPD fabrication process is becoming more important to prevent yield reductions. The purpose of this study is to develop a FPD cleaning system and a cleaning process using a two-phase flow. The FPD cleaning system consists of two parts, one being a cleaning part which includes a two-phase flow nozzle, and the other being a drying part which includes an air-knife and a halogen lamp. To evaluate the particle removal efficiency by means of two-phase flow cleaning, silica particles $1.5{\mu}m$ in size were contaminated onto a six-inch silicon wafer and a four-inch glass wafer. We conducted cleaning processes under various conditions, i.e., DI water and nitrogen gas at different pressures, using a two-phase-flow nozzle with a gap distance between the nozzle and the substrate. The drying efficiency was also tested using the air-knife with a change in the gap distance between the air-knife and the substrate to remove the DI water which remained on the substrate after the two-phase-flow cleaning process. We obtained high efficiency in terms of particle removal as well as good drying efficiency through the optimized conditions of the two-phase-flow cleaning and air-knife processes.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.4
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• pp.231-238
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• 2004

The conditions are obtained for the decomposition of solid radioactive wastes, including ion exchange resin, zeolite, charcoal, and sludge from nuclear power plant. In the process of decomposing the radioactive wastes was used the microwave acid digestion method with mixed acid. The solution after acid digestion by the following method was colorless and transparent. Each solution was analyzed with ICP-AES and AAS and the recovery yield for 5 different elements added into the simulated radioactive wastes were over $94{\%}$. The elemental analysis of destructive low and medium level radioactive wastes by the proposed microwave acid digestion conditions concerning the chemical characteristics of each radioactive waste are expected to be useful basic data for development of optimal glass formulation.

• Applied Biological Chemistry
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• v.34 no.3
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• pp.273-278
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• 1991

Methanol assimilating bacterium, Pseudomonas sp. ILS-003 was used to investigate the optimum conditions for the production of $poly-{\beta}-hydroxybutyric$ acid from methanol. For PHB production, the optimum initial pH was 6.4 and the optimum temperature was $30^{\circ}C$. Also the optimum methanol concentration was found to be 1.0%(v/v). In the PHB production, $(NH_4)_2SO_4$ was the most effective nitrogen source and the optimum concentration was 0.8 g/l, which was eqivalent to 17.4 in C/N ratio. Also, deficiency of the 2 valence metal ions in the medium had stimulating effect on PHB accumulation. Under the optimum substrate concentration, successive feeding of 0.25%(v/v) methanol was the most effective on PHB production. Under the optimum conditions, 1.94 g/l of PHB and 2.78 g/l of dry biomass were produced in 96 hours, and the yield was 69.8%(w/w).

• 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.

• Journal of Microbiology and Biotechnology
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• v.20 no.10
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• pp.1403-1414
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• 2010

Aspergillus awamori BTMFW032, isolated from sea water, produced tannase as an extracellular enzyme under submerged culture conditions. Enzymes with a specific activity of 2,761.89 IU/mg protein, a final yield of 0.51%, and a purification fold of 6.32 were obtained after purification through to homogeneity, by ultrafiltration and gel filtration. SDS-PAGE analyses, under nonreducing and reducing conditions, yielded a single band of 230 kDa and 37.8 kDa, respectively, indicating the presence of six identical monomers. A pI of 4.4 and a carbohydrate content of 8.02% were observed in the enzyme. The optimal temperature was found to be $30^{\circ}C$, although the enzyme was active in the range of $5-80^{\circ}C$. Two pH optima, pH 2 and pH 8, were recorded, although the enzyme was instable at a pH of 8, but stable at a pH of 2.0 for 24 h. Methylgallate recorded maximal affinity, and $K_m$ and $V_{max}$ were recorded at $1.9{\times}10^{-3}$M and 830 ${\mu}Mol$/min, respectively. The impacts of a number of metal salts, solvents, surfactants, and other typical enzyme inhibitors on tannase activity were determined in order to establish the novel characteristics of the enzyme. The gene encoding tannase, isolated from A. awamori, was found to be 1.232 kb, and nucleic acid sequence analysis revealed an open reading frame consisting of 1,122 bp (374 amino acids) of one stretch in the -1 strand. In silico analyses of gene sequences, and a comparison with reported sequences of other species of Aspergillus, indicate that the acidophilic tannase from marine A. awamori differs from that of other reported species.

• Korean Journal of Plant Resources
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• v.30 no.1
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• pp.88-95
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• 2017

Effects of different soil water conditions on fruit characteristics were investigated in 5-year-old 'Nero' black chokeberry trees (Aronia melanocarpa). Three kinds of drought stresses, including low water deficit, severe water deficit, and very severe water deficit, due to decline of soil water decreased the fruit quality of weight of 10 berries, soluble solid content, and anthocyanin, compared with the control (consistent water supply) during the harvest period. After longer drought stress, supply of soil water could induce berry cracking because cell size of epidermis of fruits contracted, whereas cell size of sub-epidermis and flesh expanded. Thus periodic water supply using water supply facility is needed for yield and quality of 'Nero' black chokeberry fruits.

• KSBB Journal
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• v.9 no.3
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• pp.312-318
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• 1994

The esterification of Ac-Tyr-OH was carried out in one-phase system containing ethanol by ${\alpha}$-chymotrypsin. The results of the esterification reaction are as follows. Chitin-${\alpha}$-chymotrypsin complex was found to be an effective catalyst for the esterlfication of Ac-Tyr-OH in ethanol organic solvent. The optimal conditions for the esterification were chitn/${\alpha}$-chymotrypsin ratio, 20(w/w); reaction temp., $35^{\circ}C$; reaction pH, 8.0; reaction time, 24 hrs. Also, addition of chitin in water/water-miscible organic solvent was effective for the stability of the enzyme. The esterification yield, Km and Vmax under optimal conditions were 93%, 3.093mM and 1.088mM/mg/hr, respectively.

• Korean Journal of Plant Resources
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• v.27 no.6
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• pp.701-706
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• 2014

Three highbush blueberries (Vaccinium corymbosum cvs. Bluecrop, Coville, and Northland) grown in an open field and in a rain shelter were compared to evaluate the potential benefits of rain-sheltering systems on growth and fruit quality. Shrubs grown in rain shelter flowered 5-14 days earlier and were in full bloom earlier than those in the open field. All three cultivars set fruit by nearly 90% of flowers when they were grown in the open field, but was markedly reduced when they were grown in the rain shelter, to approximately 50% for 'Bluecrop' and 'Coville'. Fruit sets ratio of 'Northland' grown in the in the rain shelter was 14.5. Fruit from greenhouse-grown 'Northland' were larger, heavier, and had more seeds per berry. Soluble sugar content (SSC) of fruits varied both with the cultivars and growing conditions. SSC of fruits grown in the greenhouse was higher in 'Bluecrop' compared to that grown in the field, but this pattern was reversed in 'Northland'. Titratable acid was significantly higher in fruits from rain shelter-grown shrubs of both 'Bluecrop' and 'Northland' than in fruits from open field-grown shrubs (P < 0.05), although there was no difference in TA with respect to growing conditions for 'Coville'. The number of seed per fruit, fruit length and diameter, weight, SSC, and TA were similar in 'Coville' shrubs grown in the open field and the rain shelter. Fruit firmness of 'Bluecrop', 'Coville', and 'Northland' was higher in the rain shelter than in the open field. 'Coville' and 'Northland' fruits harvested in the open field had higher blue chroma than those harvested in the rain shelter. However, this pattern was reversed for 'Bluecrop'. On the whole, sheltering from rain affected most fruit characteristics of the three cultivars differently. Therefore, suitable blueberry cultivars for the rain shelter should be chosen by purpose.