• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 제4회 박판성형 심포지엄
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• pp.21-28
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• 2003

Recently, instead of a matched die forming method requiring a high cost and long deliverly ten a multi-point dieless forming method using a pair of matrix type punch array as flexible dies has been developed. As this multi-point dieless forming method has some disadvantage of difficulty in precise punch control and high-cost of equipment, a new concept of multi-point dieless forming method combined with elastomer forming was suggested in this study. For optimal selection of elastomers, compression tests of rubbers, polyethylene and foams were carried out together with FEM analysis of the deformation behavior during sheet forming process using a rigid punch and elastomers. Compressive strain was concentrated on the upper central area of the elastomer under the punch, and the rubber exhibited higher concentration of the compressive strain than foams. Two-dimensional curved surface was formed successfully by the multi-point elasto-dieless forming method using an optimal combination of a rubber and foam.

• Fisheries and Aquatic Sciences
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• 제15권1호
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• pp.77-81
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• 2012

We assessed the toxicity of cryoprotectant agents (CPAs) to gametophytic thalli of red alga Porphyra yezoensis at room temperature. The CPAs used were: dimethyl sulfoxide (DMSO), ethylene glycol (EG), glycerol (GC), 1,2-butanediol (1,2-BD), 1,3-butanediol (1,3-BD), 2,3-butanediol (2,3-BD), 1,3-propanediol (1,3-PD) and propylene glycol (PG). CPA concentrations of 10, 15, 20, 25, 30, 35, 40, 45, and 50% were employed with 30 or 60 s immersion. The toxicity of the eight CPAs to gametophytic thalli of P. yezoensis was in the order: 1,3-BD < DMSO ${\approx}$ 2,3-BD ${\approx}$ PG ${\approx}$ EG < GC < 1,3-PD ${\approx}$ 1,2-BD. All thalli were more sensitive to high CPA concentrations, and most (>75%) thalli survived exposure to 10-25% CPA for 60 s. These data will facilitate selection of the optimal cryoprotectant concentration for cryopreservation of P. yezoensis thalli.

• Journal of the Optical Society of Korea
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• 제17권5호
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• pp.454-460
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• 2013

We present qualitative and quantitative component analyses on compound explosives via Terahertz time-domain spectroscopy (THz-TDS) based on a combination of wavelet thresholding and wavelength selection. Despite its importance, the field of signal processing of THz signals of compound plastic explosives is relatively unexplored. In this paper, experiment results from explosives Composition B-3 and Pentolite are newly presented, suggesting a novel signal processing procedure for in situ compound explosives detection. The proposed signal processing method demonstrates effective component analysis even in noisy and humid environments, showing significant decrease in component concentration percentage error of approximately 22.7% for Composition B-3 and 48.8% for Pentolite.

• Journal of Applied Biological Chemistry
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• 제57권3호
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• pp.197-203
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• 2014

Various parameters such as solvent selection, concentration, solid/liquid ratio, soaking time, temperature, stationary, shaking conditions, and repeated extractions were investigated in order to determine the optimum extraction conditions of ${\beta}$-glucosidase from bagasse fermented by mixed culture of Aspergillus niger NRC 7A and Aspergillus oryzae NRRL 447. Among various solvents tested, non ionic detergents gave the best results than the inorganic or organic salt solutions and distilled water. The optimum conditions for extraction of ${\beta}$-glucosidase were 30 min soaking time at $40^{\circ}C$ under shaking condition at 150 rpm, with solid/liquid ratio 1:15 (w/v), which yielded $2882.74{\pm}95.52U/g$ fermented culture (g fc) of enzyme activity. With repeated washes under the above optimum conditions, the results showed that enzyme extracted in the $1^{st}$ and $2^{nd}$ washes represents about 90% of the total activity.

• Computers and Concrete
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• 제19권6호
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• pp.737-744
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• 2017

Geopolymer Concrete is typically proportioned with activator solution leading to moderately high material cost. Such cost can be enduring in high value added applications especially when cost savings can be recognized in terms of reduction in size of the members. Proper material selection and mix proportioning can diminish the material cost. In the present investigation, a total of 27 mixes were arrived considering the mix parameters as liquid-binder ratio, slag content and sodium hydroxide concentration to study the mechanical properties of geopolymer concrete (GPC) mixes such as compressive strength, split tensile strength and flexural strength. The derived statistical Response Surface Methodology is beleaguered to develop cost effective GPC mixes. The estimated responses are not likely to contrast in linear mode with selected variables; a plan was selected to enable the model of any response in a quadratic manner. The results reveals that a fair correlation between the experimental and the predicted strengths.

• Corrosion Science and Technology
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• 제9권3호
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• pp.116-121
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• 2010

For over a decade, research and development on submerged hardware in continuous galvanizing pots has been carried out at Teck's Product Technology Centre. The outcome of numerous laboratory tests and field trials has demonstrated that dissimilar materials with comparable surface hardness are most suitable for the manufacture of roll bearings. Wear debris can be easily retained in bearings made of the same material, thereby negatively affecting bearing performance and service life. Bearings made of the same materials are also vulnerable to catastrophic failures. The dissolution of iron from the coated strip creates an iron-rich zone associated with a high concentration gradient in the vicinity of the sink roll. Consequently, the sink roll becomes a preferential site for dross pick-up. In operations involving extremely high temperatures, such as in Galvalume production, the material selection for pot hardware is immaterial to the final corrosion product of the hardware and the pick-up on the hardware.

• 분석과학
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• 제13권3호
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• pp.399-402
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• 2000

To determine the concentrations of microcystins present in lake water or in tap water using high performance liquid chromatography, it is necessary to concentrate a large volume of water samples (about 20 L) into very small volume (0.1-0.3 mL). Concentration can be conveniently done when disc type solid phase extraction (SPE) apparatus is used. Using this apparatus we have investigated the recovery rates of three kinds of microcystins, RR, YR, LR. The recovery rates were relatively low and the reproducibilities were not good either. It is expected, however, that the appropriate selection of the disc conditioning and eluting solvents and reproducible reconcentration process after SPE will improve both the recovery rates and the reproducibilities.

• 한국기계가공학회지
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• 제2권4호
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• pp.40-45
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• 2003

In this paper, to choose the optimum CBN wheel for Internal Grinding at LM Guide, among 7 types of CBN-wheels, the 2 types of CBN-wheels, which were the macrofracture CBN wheel and the microfracture CBN wheel, have been used, and the SCM420H have been used as the workpiece. The working conditions in the grinding experiments were depth-of-cut, table speed, and spindle speed for 4 types of the CBN grinding wheels, 2 types of the lubrications. By the experiments, the loading effect of the microfracture types of the CBN-wheel needed a short dressing interval and resulted in grinding wheel wear and bad surface roughness. However, a macrofracture type of CBN-wheel with the concentration of 100, CB120Q100V showed the best surface roughness quality at a low table speed for internal grinding at LM-guide.

• KSBB Journal
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• 제6권4호
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• pp.385-388
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• 1991

자란(B. striata)의 미성숙종자로 부터 유도한 embryogenic callus를 현탁배양하고 이와같은 embryogenic cell suspensions로부터 분리한 원형질체에 electroporation 방법을 사용하여 reporter genes이 들어있는 pBI121 plasmid DNA 를 도입하고 그 발현을 확인하였다. 배양된 세포에 있어서 GUS의 활성은 plasmid DNA양의 증가와 함께 높게 나타났으며, 200-300 voltage/1180 uF에서 GUS의 활성 및 원형질체의 생존율(viability)이 가장 좋았다.

• Journal of Microbiology and Biotechnology
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• 제10권1호
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• pp.115-118
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• 2000

Recombinant plasmids harboring a heterologous gene coding for the enhanced green fluorescent protein (EGFP) were transfected and expressed in Drosophila melanogaster S2 cells. A stable transformation of polyclonal cell populations expressing EGFP were isolated after 4 weeks of selection with hygromycin B. The recombinant EFGP expressed in transformed S2 cells consisted of a molecular weight of 27 kDa. EGFP expression was also confirmed by fluorometric measurement. The maximum EGFP concentration was about 9.3 mg/I. The present findings demonstrate not only the successful stable expression of EGFP in Drosophuila was about 9.3 mgI. The present findings demonstrate not only the successful stable expression of EGFP in Drosophila S2 cells, but also the use of EGFP as a reporter to analyze gene expression, with its potential of a Drosophila cell expression system for recombinant protein production being an alternative to a baculovirus-insect cell expression system.