• Journal of Welding and Joining
• /
• v.32 no.6
• /
• pp.47-55
• /
• 2014

The purpose of the study is to produce a mechanically improved weld and minimum variation of color through comparing unpulsed and pulsed GTAW (Gas Tungsten Arc Welding) for pure titanium (CP grade7) tube. Pulsed GTAW using 60 A peak current and 20 A background current (1:9) achieved the wider window of welding conditions having part and full penetration without burn-through than the case of unpulsed GTAW. Moreover, the pulsed welding reduced a discoloration on the back bead of the weld and the size of microstructures (basket weave and serrated ${\alpha}$). That is because the pulsed welding has it's a low heat input and severe weld flow induced from electric current variation. Furthermore, the pulsed welding improved the bending property of the welded Ti tube. The enhanced bending property for the pulsed GTAW was due to the insignificant discoloration on the weld surface with maintaining the metal polish.

• Applied Biological Chemistry
• /
• v.32 no.4
• /
• pp.374-377
• /
• 1989

To optimize the enzymatic saccharification of raw-starch, reaction conditions by shaking with glass beads were adapted together with ${\alpha}-amylase$ from Streptomyces sp. 4M-2 and amyloglucosidase from commercial source. When raw-starch was degraded by the ${\alpha}-amylase$ in shaking flask with beads (raw-starch : bead in diam. of 3mm=1 : 5 by weight) at the shaker speed of 300rpm, the saccharification rate of corn and potato starch were increased up to 88% and 69% after 30 hrs of reaction, respectively. Application of the amyloglucosidase in combination with the ${\alpha}-amylase$ enhanced the rate of saccharifcation: 88% of saccharification was obtained in 6 hrs for raw-corn starch under the same reaction conditions as above.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.10 no.1
• /
• pp.73-77
• /
• 2005

Plant-derived natural products have been and will continue to be valuable sources. Elicitors have been employed to modify cell metabolism in order to enhance the productivity of useful metabolites in plant cell/tissue cultures. In this study, several elicitors were used to improve the productivity of useful metabolites and to reduce culture time for archiving high concentration in P. ginseng hairy root cultures. The addition of chitosan, chitosan oligosaccharide and alginate oligosaccharide to the culture of P. ginseng hairy roots caused growth to be inhibited with the increase in elicitor concentration. The usage of the chitosan elicitor and D-glucosamine caused a slight decrease in hairy root growth, whereas total ginseng saponin accumulated slightly with the increase in elicitor concentration. When gel beads were added to the culture medium at the initial period, hairy root growth was enhanced. The maximum growth was 1.35 times higher than that of the control at $1\%$ (w/v). Total ginseng saponin content decreased due to the addition of alginate beads. This would result in consistent diffusion of lower levels of calcium ions during the culture period that promotes biomass growth.

• Journal of Korean Society for Atmospheric Environment
• /
• v.23 no.6
• /
• pp.727-733
• /
• 2007

In this study, a newly developed biotrickling system, combined with a non-thermal plasma reactor, was investigated to effectively treat gaseous contaminants such as VOCs (Volatile Organic Compounds). Three kinds of non-thermal plasmas (NTPs) such as a rod type dielectric barrier discharge (DBD) plasma, a packed bead type DBD plasma and a gliding arc (GA) plasma, were tested and compared in terms of power consumption. The rod type DBD plasma was selected as one for integration with biotrickling system due to its relatively high VOC removal efficiency, low power consumption and low pressure drop. Toluene and xylene as representatives of VOCs were used as test gases. The experiment results showed that the efficiency of biotrickling system was especially very low at the high gas concentration and high flow rate and the removal efficiencies of VOCs were considerably enhanced in the biotrickling system, when the DBD plasma was worked in front of that even at the high gas concentration and high flow rate.

• Food Science of Animal Resources
• /
• v.27 no.1
• /
• pp.110-116
• /
• 2007

Lactobacillus salivarius subsp. salivarius Nam27 with a high ${\beta}$-galactosidase activity was selected for enzymatic characterization. For purification, cell pellet was disrupted by Bead Beater, by DEAE-Sepharose and Mono-Q chromatography. The specific activity of the purified enzyme was 5,312 units/mg. The molecular weight of native monomeric ${\beta}$-galactosidase was estimated to be 30,000 dalton (monomer) by the SDS-PAGE. The optimum temperature and optimum pH were $50^{\circ}C$ and 5.0, respectively. This enzyme was stable between 35 and $55^{\circ}C$. ${\beta}$-galactosidase activity was lost rapidly above pH 7.0. But ${\beta}$-galactosidase was more stable at pH 4.0 (acidic conditions). And ${\beta}$-galactosidase activity was lost rapidly above $65^{\circ}C$ after 10 min incubation. $Ca^{2+}$ and $Zn^{2+}$ metal ions enhanced ${\beta}$-galactosidase activity by 164.09% and 127.37% while $Cu^{2+}$, $Fe^{3+}$ and $Mn^{2+}$ lowered ${\beta}$-galactosidase activity by 58.29%,85.10% and 77.66% respectively. Other metal ions didn't affect ${\beta}$-galactosidase activity significantly.

• Journal of Korean Society on Water Environment
• /
• v.23 no.1
• /
• pp.155-160
• /
• 2007

Constructed wetland has been widely used for the treatment of sewage, stormwater runoff, industrial wastewater, agricultural runoff, acid mine drainage and landfill leachate. For the removal of nitrogen and phosphorus, uptake by plants and adsorption to media material are the major processes, and, therefore, the selection of media with specific adsorption capacity is the critical factor for the optimal design of wetland along with the selection of appropriate plant species. In this study, two media materials (loess bead and mixed media) possessing different adsorption characteristics for ammonium and phosphate were selected, and their adsorption characteristics were evaluated. In addition, the performance of subsurface-flow wetland systems employing these media was evaluated in both batch and continuous flow systems. With LB medium, beter phosphorus removal was observed, while better ammonia removal was obtained with MM medium. In addition, enhanced removal efficiencies were observed in the wetland systems employing both media and aquatic plants, mainly due to the better environment for microbial growth. As a result, appropriate selection or combination of media with respect to the inflow water quality maybe important factors for the successful design and operation of wetland systems.

• KSBB Journal
• /
• v.9 no.5
• /
• pp.525-531
• /
• 1994

Tyrosinase has two types of enzymatic activities, cresolase catalyzing the hydroxylation of monophenol and catecholase catalyzing the oxidation of o-phenol. Gradual inactivation of the enzyme during the reaction is a barrier to be overcome for the commercial application of the enzyme. Tyrosinase was stabilized by modifying the lysine residue of the enzyme using glutaraldehyde. In addition to that, tyrosinase was also stabilized by adapting the continuous reactor system. In packed bed reactor quinone could be easily removed, so the stability of tyrosinase increased. Borate buffer retarded the reaction rate of catechol to quinone and consequently decreased the tyroslnase inactivation. Tyrosinase immobilizer on controlled pore glass showed significantly enhanced stability in a packed-bed reactor.

• Journal of the Semiconductor & Display Technology
• /
• v.11 no.1
• /
• pp.21-27
• /
• 2012

The optical diffuser for direct-lit LED backlight unit was prepared by using extrusion compounding followed by thermoforming process. Poly(methyl methacrylate) (PMMA) with superior optical characteristics and polycarbonate (PC) with good thermal property were used as base resins, and crosslinked polystyrene (PS) and PMMA beads as diffusing agents were incorporated into resin matrix to derive light scattering and diffusing action. In the compounded plate, the diffusing beads were observed to be dispersed uniformly and distinctly in the continuous phase. The inclusion of polymeric beads up to 3 wt% substantially enhanced the optical characteristics such as luminance, luminance uniformity, haze for the diffuser. Two different diffusers of PC and PMMA-based compound with various compositions were compared in terms of measured optical, thermal, and mechanical properties, which would be expected to be utilized for the industrial application of LED backlight unit.

• Journal of the Korean Ceramic Society
• /
• v.52 no.5
• /
• pp.380-383
• /
• 2015

We prepared the $TiO_2$ layer with 0 ~ 4 wt% of polystyrene (PS) beads having a radius of 250 nm to increase the dye adsorption and energy conversion efficiency (ECE) of a dye sensitized solar cell (DSSC). Then, we fabricated DSSCs using $0.45cm^2$ active area. FE-SEM was used to characterize the microstructure consisting of $TiO_2$ layer and PS beads. UV-VIS-NIR was used to determine the optical absorbance of working electrodes (WEs). Solar simulator and potentiostat were used to determine the photovoltaic properties. We observed that pores having a radius of 250 nm were formed with the density of $0.15ea/{\mu}m^2$ in $TiO_2$ layers after conducting the sintering process. The absorbance in visible light regime was found to increase with the increase in the amount of PS beads. The ECE increased from 4.66% to 5.25% when the amount of PS beads was increased from 0 to 4 wt%. This is because the pores of PS beads increased the adsorption of dye. Our results indicate that the ECE of the DSSCs can be enhanced by the addition of an appropriate amount of PS beads into $TiO_2$ layers.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.6 no.6
• /
• pp.419-425
• /
• 2001

A dense pellicular solid matrix has been fabricated by coating 4% agarose gel on to dense zironia-silica(ZS) spheres by watr-in-oil emulsification . The agarose evenly laminated the ZS bead to a depth of 30㎛, and the resultin gpellicular assembly was characterised by densities up to 2.39g/mL and a mean particle dimeter of 136 ㎛. In comparative fluidisation tests, the pellicular solid phase exhibited a two-fold greater flow velocity than commercial benchmark ad-sorbents necessary to achieve common values of bed expansion. Furthermore, the perlicular parti-cles were characterised by improved qualities of chromatographic behaviour, particularly with re-spect to a three-fold increase in the apparent effective diffusivity of lysozyme within a pellicular assembly modified with Cibacron Blue 3GA. The properties of rapid protein adsorption/desorp-tion were attributed to the physical design and pellicular deployment of the reactive surface in the solid phase. When combined with enhanced feedstock throughput, such practical advantages recommend the pellicular assembly as a base matrix for the selective recovery of protein products from complex, particulate feedstocks(whole fermentation broths, cell disruptates and biological extracts).