• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.555-560
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• 2014

In this paper, in order to develop outstanding Pb-free composition ceramics, the $Fe_2O_3$-doped ($Na_{0.525}K_{0.443}Li_{0.037}$)($Nb_{0.883}Sb_{0.08}Ta_{0.037}$)$O_3$ + 0.3 wt% $Bi_2O_3$ + x wt% $Fe_2O_3$ (x= 0~1.0 wt%)(abbreviated as NKL-NST) lead-free piezoelectric ceramics have been synthesized using the ordinary solid state reaction method. The effect of $Fe_2O_3$-doping on their microstructure and electrical properties were investigated. XRD diffraction pattern studies confirm that $Fe_2O_3$ completely diffused into the NKL-NST lattice to form a new stable soild solution with $Fe^{3+}$ entering the $Nb^{5+}$, $Sb^{5+}$ and $Ta^{5+}$ of B-site. And, phase structure of all the ceramics exhibited pure perovskite phase and no secondary phase was found in the ceramics. The ceramics doped with 0.6 wt% $Fe_2O_3$ have the optimum values of piezoelectric constant($d_{33}$), planar piezoelectric coupling coefficient($k_p$) and mechanical quality factor($Q_m$) : $d_{33}$ = 233 [pC/N], $k_p$= 0.44, $Q_m$= 95. These results indicate that the ($Na_{0.525}K_{0.443}Li_{0.037}$)($Nb_{0.883}Sb_{0.08}Ta_{0.037}$)$O_3$ +0.3 wt% $Bi_2O_3$ + 0.6 wt% $Fe_2O_3$ ceramic is a promising candidate for lead-free piezoelectric ceramics.

• Biomedical Science Letters
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• v.2 no.1
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• pp.49-55
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• 1996

The objective of this study was to develop a paper strip which could determine E. coli qualitatively and quantitatively in water, wastewater, drinks, or food. This paper strip method was a simple and rapid test method that determine E. coli by visual identification. In this study, nutrient culture media were formulated and characterized for optimum conditions. Paper strips were then prepared by impregnating into the media and dried at $60^\circ$C. The test procedure is quite simple to use. The paper strip was dipped into a sample, and excess sample was removed. The strip was then incubated at $37^\circ$C for 16 to 20 hours and the number of colonies on the strip was counted. The color of the colony spots produced by microorganisms varied depending on the media formulation. Violet-red spots were produced by E. coli. The test method was simple, rapid and no special laboratory equipment was necessary for visual identification. Therefore, this test method is applicable to on-site tests such as field tests or home tests. The paper strip method was compared with the standard agar plate method and Japanese commercial product. The method of the economical preparation of test strips was studied for production on industrial scale.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.4
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• pp.695-704
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• 2016

Rubber deposited during aircraft landing is known as the main cause of reducing surface friction force on wet surfaces. Thus, rubber deposits are removed at regular intervals for sae airplane landing. The high-pressure waterblast method, widely used for the removal of rubber deposits, is regarded as the main cause for the loss of surface material because in this method, water hits the surface directly at a high pressure. In this study, a rubber removal primer is developed to reduce surface damage by lowering the pressure of waterblast relatively during the removal of rubber deposits such that the deposits are removed efficiently even with a lower water pressure. To achieve this, basic materials appropriate for the primer were selected and their performance, penetration rate, and site applicability were evaluated. Based on the evaluations, the proportion of additive required for improving the performance of the basic materials was first determined. Then, the optimum mix ratio was derived through the evaluation of the effect on pavements, and the development of the rubber removal primer was completed.

• Journal of Applied Biological Chemistry
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• v.53 no.4
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• pp.189-194
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• 2010

We confirmed the hypo-osmotic shock strengths and duration, different type of vectors, and subcelluar localization to identify the optimum analysis condition of plant aquaporin activity in Xenopus ooctye using Arabidopsis thaliana AtPIP2-1 gene. Six minutes and 1/5ND buffer hypoosmotic shock treatment was the best condition to show the maximum swelling of Xenopus oocytes where AtPIP2-1 was expressed using pcDNA3.1 vector. AtPIP2-1 protein was expressed more efficiently in pGEMHE vector which has 5' and 3' UTR (untranslation region) of Xenopus ${\beta}$-GLOBIN gene in multiple cloning site than in pcDNA3.1 vector. Also green fluorescence of GFP fused to AtPIP2-1 was detected onto oocyte plasmamembrane where is the proper subcellular localization target of AtPIP2-1.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.176-183
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• 2010

Endosulfan degrading ability of Klebsiella oxytoca KE-8 immobilized by entrapment with activated carbon was examined. Endosulfan degradation by the immobilized bacterial strains on several different activated carbon based support materials was investigated. Based on results, activated carbon ($8\times30$ mesh) was chosen as a support material. The immobilized Klebsiella oxytoca KE-8 with the cell density of 4 mg $g^{-1}$ (dry weight) degraded 22.18 ug $ml^{-1}$ endosulfan within 5 days at pH 7.0, $30^{\circ}C$ in batch shake flask cultures. Also, we an experimented recycle packed bed column mode and continuous packed bed column mode for endosulfan degradation. Under optimum operation condition, the immobilized cells in a laboratory scale pack bed column with support beads were able to degrade endosulfan completely in defined minimal salt medium at a maximum rate of 129.6 ug $ml^{-1}$ per day. Moreover, the endosulfan degradation activity could be demonstrated at $4^{\circ}C$ for one month without significant decrease in activity. Results of this study suggest that immobilized cells of Klebsiella oxytoca KE-8 might be applicable to endosulfan contaminated site.

• Journal of Microbiology and Biotechnology
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• v.26 no.7
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• pp.1163-1172
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• 2016

The Ω-loop is a nonregular and flexible structure that plays an important role in molecular recognition, protein folding, and thermostability. In the present study, molecular dynamics simulation was carried out to assess the molecular stability and flexibility profile of the porcine trypsin structures. Two Ω-Loops (fragment 57-67 and fragment 78-91) were confirmed to represent the flexible region. Subsequently, glycosylation site-directed mutations (A73S, N84S, and R104S) were introduced within the Ω-loop region and its wing chain based on its potential N-glycosylation sites (Asn-Xaa-Ser/Thr consensus sequences) and structure information to improve the thermostability of trypsin. The result demonstrated that the half-life of the N84S mutant at 50℃ increased by 177.89 min when compared with that of the wild-type enzyme. Furthermore, the significant increase in the thermal stability of the N84S mutant has also been proven by an increase in the T_m values determined by circular dichroism. Additionally, the optimum temperatures of the wild-type enzyme and the N84S mutant were 75℃ and 80℃, respectively. In conclusion, we obtained the thermostability-improved enzyme N84S mutant, and the strategy used to design this mutant based on its structural information and N-linked glycosylation modification could be applied to engineer other enzymes to meet the needs of the biotechnological industry.

• Tunnel and Underground Space
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• v.16 no.6 s.65
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• pp.467-475
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• 2006

The use of face bolt method has been increasing abroad recently. Hence, many tests and measurements are being conducted and reported. Also, it is well hewn that determination of the installation number of foe bolts in the design stage is very difficult due to difference of the ground condition and the type of a bolt to be used. First of all, the type, the number, etc. of bolts used in various tunnel construction sites, investigated, are analyzed. The relationship between bolt and ground condition could not be found because bolts have been used with the other support methods in many cases. In the laboratory test and numerical analysis based on the site investigation, the behavior of ground and pipes installed on the tunnel face to support has been examined. Especially, the installed number is focused on. According to the result of tests, the surface settlement and the axial displacement of the face decrease exponentially as the number of installed bolts increases.

• Polymer(Korea)
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• v.34 no.1
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• pp.14-19
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• 2010

Applying acrylic silane monomer for determent of weathering damage of stone cultural assets from various sources was investigated to improve inorganic affinity of polymer impregnated to the stone for conservation treatment using impregnation of acrylic polymers under pressure. Radical polymerization was carried out with various mixture ratios of methacrylate (MMA), as the base monomer, and vinyl trimethoxy silane (VTMS). Subsequently, according to the changes of glass transition temperatures, average molecular weights, and storage moduli of the obtained copolymers, the case of adding 1 wt% of benzoyl peroxide, polymerization for 8 hrs, and mixing 5 mol% of VTMS to MMA was the optimum condition of monomer ratio and polymerization. Practically, fresh granites collected in domestic site and weathered stones were treated by following the obtained result above, and then, the moisture absorption, impact, acid resistance, and adhesion properties of the treated stones were compared to those of the corresponding stones treated with MMA only. It was found that those properties of the stones treated with PMV5 were considerably improved.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.2
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• pp.203-214
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• 2007

This study aimed at researching the process selection for two-stage and dual media filtration system, as a technology substituting the existing sand filter without expanding the site when retrofitting an old filter bed or designing a new one. In order to select the process for optimum complex filtration system, three running conditions have been tested. Test results demonstrated that Run 3 in which the 1st stage was filled with anthracite and coarse sand, and the 2nd stage was filled up with activated carbon and fine sand reduced the head loss and the load of turbidity substances. Also, Run 3 showed better performance in removing TOC, particle counts, THMFP and HAAFP, compared to other two conditions. 99 % of Cryptosporidium was removed. Bisphenol-A was rarely removed from the 1st stage of coarse sand and 2nd stage of fine sand, but 99 % of it was removed from the 2nd stage of activated carbon. In conclusion, when it is required to retrofit an old rapid filter bed or design a new one for the purpose of improving filtration performance, the following two-stage and dual media filtration system is suggested: the 1st stage of filter bed needs to be filled up with coarse sand to remove turbidity as the pretreatment for extending duration of filtering, the top part of 2nd stage needs to be filled up with granular activated caron to remove dissolved organic matters and others as the main process, and finally the bottom part of 2nd stage needs to be filled up with fine sand as the finishing process.

• Journal of IKEEE
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• v.5 no.2 s.9
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• pp.221-231
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• 2001

In this paper, we propose an efficient requantization method for INTRA frames in heterogeneous transcoding from MPEG-1 to MPEG-4 simple profile. The quantizer for MPEG-1 INTRA MB usually uses a quantization weighting matrix while the quantizer for MPEG-4 simple profile doesn't. As a result, the quantization step sizes of the two quantizers may not be the same even for the same quantization parameter. Due to this mismatch in the quantization step site, the transcoded MPEG-4 sequence suffers from serious quality degradation and the number of bits produced by transcoding increases from the original MPEG-1 video sequence. To solve these problems, we propose an efficient method to find a near-optimum reconstruction level in the transcoder. We also present a PDF (probability distribution function) estimation method for the original DCT coefficients of MPEG-1 video sequence, which is required for the proposed requantization. Experimental results show that the proposed method gives $0.3{\sim}0.6dB$ improvement in PSNR over the conventional method, even at the reduced bit-rate about $5{\sim}7%$ from the conventional method.