• Journal of the Korean Society for Environmental Technology
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• v.19 no.6
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• pp.543-549
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• 2018

In this study, the treatment efficiency of inorganic membrane according to the flux that blending raw water was investigated at the laboratory level. Based on the results of each blending and flux, we obtained the best efficiency according to each measurement item. The treatment efficiencies were different depending on the raw water and treatment amount of the treated water. Especially, turbidity removal efficiency was high. In the case of $UV_{254}$, the removal efficiency according to the concentration of the raw water and the removal efficiency according to the flux of the treated water showed a maximum of 69 % to minimum of 48 %. In the case of TOC and DOC, the processing efficiency was 22 % and 28 %, respectively, because the organic value of the raw water was low. These results suggest that there is an optimal process to effectively remove contaminants from the inorganic membrane process, and it is necessary to optimize it according to operating conditions.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.511-520
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• 2016

The most energy-demanding step of wastewater treatment is the aeration-dependent elimination of organic carbon. Microbial fuel cells (MFCs) offer an alternative strategy in which carbon elimination is conducted by anaerobic microorganisms that transport respiratory electrons originating from carbon oxidation to an anode. Hence, chemical energy is directly transformed into electrical energy. In this study, the use and stability of barcode-containing exoelectrogenic model biofilms under non-axenic wastewater treatment conditions are described. Genomic barcodes were integrated in Shewanella oneidensis, Geobacter sulfurreducens, and G. metallireducens. These barcodes are unique for each strain and allow distinction between those cells and naturally occurring wild types as well as quantification of the amount of cells in a biofilm via multiplex qPCR. MFCs were pre-incubated with these three strains, and after 6 days the anodes were transferred into MFCs containing synthetic wastewater with 1% wastewater sludge. Over time, the system stabilized and the coulomb efficiency was constant. Overall, the initial synthetic biofilm community represented half of the anodic population at the end of the experimental timeline. The part of the community that contained a barcode was dominated by G. sulfurreducens cells (61.5%), while S. oneidensis and G. metallireducens cells comprised 10.5% and 17.9%, respectively. To the best of our knowledge, this is the first study to describe the stability of a synthetic exoelectrogenic consortium under non-axenic conditions. The observed stability offers new possibilities for the application of synthetic biofilms and synthetically engineered organisms fed with non-sterile waste streams.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.29-40
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• 2023

Xanthan gum and starch compound biopolymer (XS), an environmentally friendly soil-binding material produced from natural resources, has been suggested as a slope protection material to enhance soil strength and erosion resistance. Insufficient wet strength and the consequent durability concerns remain, despite XS biopolymer-soil treatment showing high strength and erosion resistance in the dried state, even with a small dosage of soil mass. These concerns need to be solved to improve the field applicability and post-stability of this treatment. This study explored the utilization of an alkaline-based cation crosslinking method using calcium hydroxide and sodium hydroxide to induce non-thermal gelation, resulting in the enhancement of the wet strength and durability of biopolymer-treated soil. Laboratory experiments were conducted to assess the unconfined compressive strength and cyclic wetting-drying durability performance of the treated soil using a selected recipe based on a preliminary gel formation test. The results demonstrated that the uniformity of the gel structure and gelling time varied depending on the ratio of crosslinkers to biopolymer; consequently, the strength of the soil was affected. Subsequently, site soil treated with the recipe, which showed the best performance in indoor assessment, was implemented on the field slope at the bridge abutment via compaction and pressurized spraying methods to assess feasibility in field implementation. Moreover, the variation in surface soil hardness was monitored periodically for one year. Both slopes implemented by the two construction methods showed sufficient stability against detachment and scouring, with a higher soil hardness index than the natural slope for a year.

• Journal of Animal Science and Technology
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• v.63 no.5
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• pp.1008-1017
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• 2021

This study was conducted to investigate the effect of different fattening periods on the growth performance, carcass characteristics, and economic traits of Holstein steers. Sixty Holstein steers (8.0 ± 0.28 months old) with an average body weight (BW) of 231.88 ± 2.61 kg, were randomly allocated to five different fattening period treatments: 20, 21, 22, 23, and 24 months (n = 12 in each treatment group). Final BW and average daily gain (ADG) did not differ among the treatment groups during the early fattening period. At the late stage of the fattening period, the final BW of steers in the 24-month treatment group (812.84 kg) was greater (p < 0.05) than that of steers in the 20-month treatment group (750.39 kg). During the same period, steers in the 20- and 21-month treatment groups had a significantly higher (p < 0.05) ADG than those in the 22-month treatment group. The highest ADG (1.36 kg/day) was found in the 20-month treatment group (1.36), followed by the 21- (1.33 kg/day), 22- (1.22 kg/day), 23- (1.21 kg/day), and 24- (1.14 kg/day) month treatment groups. The feed conversion ratio (FCR) increased as the fattening period increased, and the FCR was 12.88% lower in the 20-month treatment group than in the 24-month treatment group. However, no significant differences were detected in back-fat thickness, loin area, marbling score, and chemical characteristics (water, crude protein, and crude fat content) among the treatment groups. The composition of fatty acids including C18:0, C18:1, saturated fatty acids, unsaturated fatty acids, and poly-unsaturated fatty acids did not differ among the experimental groups. As the fattening period increased, production costs increased, resulting in a decrease in gross income. The gross income for steers in the 24-month treatment group was 35.8% and 23.5% lower than that for steers in the 20- and 21-month treatment groups, respectively. Taken together, the best performance, including the ADG, FCR, and gross income, was obtained when the fattening program of the Holstein steers lasted 20 months.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.684-701
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• 2016

The Gaussian process model (GPM) is a flexible surrogate model that can be used for nonparametric regression for multivariate problems. A unique feature of the GPM is that a prediction variance is automatically provided with the regression function. In this paper, we estimate the safety margin of a nuclear power plant by performing regression on the output of best-estimate simulations of a large-break loss-of-coolant accident with sampling of safety system configuration, sequence timing, technical specifications, and thermal hydraulic parameter uncertainties. The key aspect of our approach is that the GPM regression is only performed on the dominant input variables, the safety injection flow rate and the delay time for AC powered pumps to start representing sequence timing uncertainty, providing a predictive model for the peak clad temperature during a reflood phase. Other uncertainties are interpreted as contributors to the measurement noise of the code output and are implicitly treated in the GPM in the noise variance term, providing local uncertainty bounds for the peak clad temperature. We discuss the applicability of the foregoing method to reduce the use of conservative assumptions in best estimate plus uncertainty (BEPU) and Level 1 probabilistic safety assessment (PSA) success criteria definitions while dealing with a large number of uncertainties.

• Horticultural Science & Technology
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• v.29 no.3
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• pp.260-266
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• 2011

An efficient protocol was established for high frequency somatic embryogenesis through a callus culture of Coelogyne cristata. The best frequency of callusing was obtained from a PLB segment (3-5 mm) cultured on MS medium supplemented with coconut water (CW) and a combination of both 3 $mg{\cdot}L^{-1}$ of 2,4-D and BA. When the calli were sub-cultured on the MS medium without any PGRs, the average number of somatic embryos were higher than those with PGRs treatment. NAA is the most critical factor among PGRs, which dramatically hindered for the formation of a somatic embryo. The efficacy of the addition of coconut powder (CP) for somatic embryogenesis was almost the same in all treatments. However, the number of somatic embryos formed distinctly depended on age of the callus. The somatic embryos converted into healthy plants with well-developed shoots on the same medium. Plantlets showed the best responses of root and shoot growth when transferred to $\frac{1}{2}$ MS medium containing 1.5 $g{\cdot}L^{-1}$ of activated charcoal. All plants with above 3.0-cm-high were successfully acclimatized in the greenhouse.

• Journal of Electrochemical Science and Technology
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• v.12 no.1
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• pp.101-111
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• 2021

To improve the potential of single chamber microbial fuel cells (SCMFCs) as an applicable technology, the main challenge is a practical application for larger scales bioenergy production from potent exoelectrogenic microorganism with real dairy wastewater. To increase power generation, three individual MFCs were together operated in series best under the fed batch condition for 15 days. The volume of MFC 1 and MFC 2 is "300 mL" and MFC 3 is "500 mL" respectively. The individual MFCs 1, MFC 2 and MFC 3 gives an open circuit voltage of 0.60 V, 0.66 V and 0.55 V and result in total working voltage when connected in series of 1.745V, which lead an LED to glow. The maximum power densities obtained from MFC 1, MFC 2 and MFC 3 are 62 mW/㎡, 50 mW/㎡ and 45 mW/㎡ (normalized to the surface area of the anodic electrode, which was 50 ㎠ for all three MFCs), and corresponding to current densities of 141 mA/㎡, 155 mA/㎡ and 123 mA/㎡, respectively. Therefore this work suggests the cheapest way to connect microbial fuel cells in series to gain power with the lowest operating cost and chemical oxygen demand (COD) removal.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.31-39
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• 2005

Direct methanol fuel cell (DMFC) is considered as a candidate for portable power sources, that could overcome the disadvantages of lithium battery. But in order to attain commercial viability the long term stability of the DMFC should be achieved. Understanding the long-term behavior of membrane-electrode assembly (MEA) is a prerequisite to this purpose and the optimization of the MEA is also needed. In this study we have investigated the changes in performance and electrochemical properties of the MEA during extended operation and the effects of heat treatment of MEA on the long-term performance. The MEAs have been treated in an autoclave with saturated water vapor at 120$^{\circ}C$, vacuum oven at 140$^{\circ}C$ and boiling in organic solvents. The autoclaved MEA was found to be have the best long term performance. The on-off operation mode also increased the performance probably due to effective removal of products from the electrodes. Physical and electrochemical analyses using a scanning electron microscope, impedance analyser and half-cell technique have been done to characterize the MEAs.

• Journal of the Korean Ceramic Society
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• v.52 no.4
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• pp.229-233
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• 2015

Currently, the majority of commercial white LEDs are phosphor converted LEDs made of a blue-emitting chip and YAG yellow phosphor dispersed in organic silicone. However, silicone in high-power devices results in long-term performance problems such as reacting with water, color transition, and shrinkage by heat. Additionally, yellow phosphor is not applicable to warm white LEDs that require a low CCT and high CRI. To solve these problems, mixing of green phosphor, red phosphor and glass, which are stable in high temperatures, is common a production method for high-power warm white LEDs. In this study, we fabricated conversion lenses with LUAG green phosphor, SCASN red phosphor and low-softening point glass for high-power warm white LEDs. Conversion lenses can be well controlled through the phosphor content and heat treatment temperature. Therefore, when the green phosphor content was increased, the CRI and luminance efficiency gradually intensified. Moreover, using high heat treatment temperatures, the fabricated conversion lenses had a high CRI and low luminance efficiency. Thus, the fabricated conversion lenses with green and red phosphor below 90 wt% and 10 wt% with a sintering temperature of $500^{\circ}C$ had the best optical properties. The measured values for the CCT, CRI and luminance efficiency were 3200 K, 80, and 85 lm/w.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1397-1400
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• 1999

The grape juice was found to have a good quality when grape was pressed after heating at $80^{\circ}C$ for 30 min. The extraction yield of juice from grape was above 75%(v/w). The yield was lower than 60% when grape was heated below $60^{\circ}C$, although the taste was good. But when grape was overheated, for example, at $100^{\circ}C$ and pressed, the grape juice had dark brown color and showed off-flavor. The grape juice of which sugar content was above $14^{\circ}Brix$ and the ratio of sugar content to total acidity was over 20 was found to have the best quality to drink.