• Journal of the Korean Society for Precision Engineering
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• v.28 no.7
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• pp.777-782
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• 2011

Micro features on the surface are well-known to have significant effects on optical or mechanical properties such as the optical interference, reflectance at the surface, contact angle, interfacial friction, etc. These surface micro features are increasingly employed to enhance the functionality of the applications in various application areas such as optical components for LCD or solar panel. Diverse surface features have been proposed and some of them are showing excellent efficiency or functionality, especially in optical applications. Most applications employing the micro features need manufacturing process for mass production and the injection molding and roll-to-roll forming, which are typical processes for mass production adopting polymeric materials, may be also preferred for micro patterned plastic product. Since the functionality or efficiency of the surface structures generally depends on the shape and the size of the structure itself or the array of the structures on the surface, it would be very important to replicate the features very precisely as being designed during the molding the micro pattern applications. In this paper, a series of research activities is introduced for roll-to-roll forming of micro patterned film including filling of patterns with UV curable resin, demolding of surface structures from the roll tool, control of surface energy and cure shrinkage of resin and dispose time and intensity of the UV light for curing of UV curable resin.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.37-43
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• 2006

The coagulation efficacy of Al-based coagulants (such as Alum, PACS, and PACC) was investigated to ascertain removal efficiencies of turbidity and phosphate with variation of solution pH, coagulant dosages, and pre-dilution ratios. The efficacy of Al-based coagulants was maximized in the pH range of 6~9. Under the initial condition of pH 8, $10mg/L\;{PO_4}^{3-}$, and 20 NTU, Al-based coagulants exhibited a similar efficacy in the removal of turbidity, whereas the removal efficiency of phosphate was clearly dependent on the basicity of coagulants: Alum (0%) > PACS (45~50%) > PACC (70%). At high initial turbidity of 100 NTU, polymeric coagulants, such as PACS and PACC, exhibited a higher removal efficiency of turbidity compared to Alum. In comparison to direct injection of coagulants at low initial turbidity (20 NTU), 500~2000 times pre-diluted Alum, exhibited reduced coagulation efficacy; however, removal efficiencies of turbidity and phosphate increased with the increase of retention time. Pres-diluted PACC exhibited the enhanced coagulation efficacy followed by silght decrease of the removal efficiencies with increase of the retention time. At high initial turbidity of 100 NTU, pre-diluted Alum and PACC exhibited higher removal efficiencies of turbidity and phosphate.

• Fisheries and Aquatic Sciences
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• v.23 no.4
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• pp.7.1-7.8
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• 2020

Background: To minimize the use of antibiotics and to obtain a more sustainable fish culture and aquaculture industry, development of alternative natural source of immunostimulant to replace antibiotic in aquafeed is highly needed. Objective: Dietary inclusion effect of yacon (YC), ginger (GG), and blueberry (BB) on growth, body composition, and disease resistance of black rockfish against Vibrio anguillarum was compared to ethoxyquin (EQ). Methods: Four hundred eighty juvenile (an initial weight of 4.2 g) fish were randomly distributed into 12 of 50 L flowthrough tanks (forty fish per tank). Four experimental diets were prepared; the control (Con) diet with 0.01% EQ inclusion, and YC, GG, and BB diets at 1% each additive inclusion. Each additive was included into the experimental diets at the expense of wheat flour. Each diet was assigned to triplicate tanks of fish and hand-fed to satiation twice daily for 8 weeks. At the end of 8-week feeding trial, 20 fish from each tank fish were artificially infected by intraperitoneal injection with 0.1 mL of culture suspension of pathogenic V. anguillarum containing 3.3 × 10⁶ cfu/mL respectively. Fish were monitored for the following 8 days after V. anguillarum infection and dead fish were removed every 6 h for the first 4 days and 12 h for the rest of the study. Results: Weight gain, specific growth rate (SGR), and feed efficiency ratio (FER) of fish fed the YC diet was higher than those of fish fed all other diets. However, feed consumption, protein efficiency ratio, and protein retention was not affected by dietary additive. Moisture, crude protein, and crude lipid content of the whole body of fish were affected by dietary additive. Analysis of the Kaplan-Meier survival curves showed that survival of fish fed the YC, BB, and GG diets was higher than the Con diet. Conclusion: Oral administration of YC can improve not only weight gain, SGR, and FER of black rockfish, but lower mortality of rockfish at occurrence of V. anguillarum.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.506-512
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• 2018

The fine dust generated in the home and restaurant business occupies a low ratio of about 4% of the total fine dust emissions. However, at the foodservice business, the rate of change of the pollutant concentration is very high, so that the temporary fine dust concentration can be measured up to 60 times. The pollutants generated from non-industrial combustion plants consist of particulate fine dust and gaseous organic compounds. To remove these pollutants, cleaning dust collection system, which is an effective system for simultaneous removal of gaseous and particulate matter, is applied. This is a method of increasing the probability of diffusion capture of the Brownian motion by pressurized liquid injection method using the atomizing nozzle. The dust removal efficiency of the fine dust collecting system was analyzed by nozzle spraying air pressure condition and angle using the manufactured fine dust removing system. As a result, it was confirmed that the efficiency of removal of fine dust and gaseous organic compounds was more than 90%. The developed system is expected to be highly usable in the future because it can remove particulate dust from the existing plant hood system without any installation cost.

• Resources Recycling
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• v.28 no.4
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• pp.44-50
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• 2019

In the electric arc furnace process, the chemical energy such as the heat of oxidation reaction and the heat of carbon combustion etc. is consumed as 30% of the total input energy. In order to reduce $CO_2$ emission in EAF, it is necessary to decrease the use of electric power energy during scrap melting stage and increase the use of chemical energy. In general, when the carbon materials is individually charged into the molten steel, the carbon materials floated to the slag layer due to low density before it is dissolved in molten steel. When the concentration of carbon in the molten steel is high, the combustion energy of carbon by oxygen injection can lower the electric power energy and improve the chemical energy consumption. Therefore, an efficient charging methods of carbon material is required to increase the efficiency of carbon combustion heat. On the other hand, Al-dross, which is known as a by-product after Al smelting, includes over 25 mass% of metallic Al, and the oxidation heats of Al is lager than that of carbon. However, the recycling ratio fo Al-dross was very low and is almost landfilled. In order to effectively utilize the heats of oxidation of Al in Al-dross, it is necessary to study the application of Al-dross in the steel process. In this study, the dissolution efficiency of carbon and aluminum in molten steel was investigated by varying the reaction temperature and the mixing ratios of coke and Al-dross.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.11
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• pp.1673-1685
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• 2019

Objective: To evaluate the efficacy of treatments based on gonadotrophin-releasing hormone (GnRH), GnRH-prostaglandin $F2{\alpha}$ ($PGF2{\alpha}$), and/or intense exposure to novel rams to induce fertile estrus without the use of steroid hormones in seasonally anestrous Suffolk ewes. Methods: In the first experiment, ewes were treated with one injection of GnRH, two injections of GnRH administered 7 days apart, or a sequence of GnRH-$PGF2{\alpha}$-GnRH (GPG). In the second experiment anestrous ewes were exposed, for 36 days starting on the day of weaning, to groups of four rams of three different breeds that were alternated every day. Besides exposure to the male effect (ME), the ewes were injected with saline solution (ME group, n = 20), with GnRH (ME-GnRH group, n = 20) or with a sequence of GnRH-$PGF2{\alpha}$-GnRH (ME-GPG group, n = 20). The rams used for male-effect were fitted with aprons to prevent mating, and ewes detected in estrus were bred to selected fertile rams. Ovarian activity was monitored by progesterone determinations in both experiments. Results: In the first experiment sustained induction of ovarian activity was not achieved and no ewe was detected in estrus. In the second experiment induction of sustained ovarian activity was achieved in all groups. Most of the ewes were detected in estrus, 76.7% of the ewes were mated during a 36-d breeding period and 71.7% of all the ewes became pregnant during that period. No significant differences between groups were found for any of these variables. However, estrus detection efficiency was higher in the ME-GnRH group than in the ME group (p<0.05). Conclusion: An intense male-effect, that included the continuous presence and frequent alternation of several rams of different breeds, was sufficient to induce ovarian activity and fertile estrus in Suffolk ewes during the period of deep anestrus without the use of hormones, although addition of GnRH improved the efficiency of estrus detection.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.33-44
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• 2019

Clinker layer is a stratum structure distributed in volcanic area such as Jeju Island. The clinker layers were formed in between the repetitive action of eruption and solidification of lava flows. Since the clinker layer contains a large amount of voids accompanied by the lava gas ejection process, there is a possibility of inducing overall stability of the ground due to the low stiffness and strength of the clinker layer. Therefore, in this study, site investigation was carried out at both ends of the 00 bridge where the clinker layers exist. And, based on the ground survey results, the behavior of shallow foundations was analyzed numerically. In addition, the improved shallow foundation behavior in grouting substitution using the chemical injection method of the clinker layer was compared with the shallow foundation behavior in the ground, and the grouting substitution efficiency of each layer was analyzed. As a result, the bearing capacity, the replacement efficiency and elastic settlement were different according to the presence or absence of the sediment layer. This is because the sediment layer has a lower stiffness and density than the clinker layer.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.6
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• pp.393-402
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• 2020

In the membrane process, it is important to improve water treatment efficiency to ensure water quality and minimize membrane fouling. In this study, a pilot study of membrane process using reservoir water was conducted for a long time to secure high flux operation technology capable of responding to influent turbidity changes. The raw water and DAF(Dissolved Air Flotation) treated water were used for influent water of membrane to analyze the effect of water quality on the TMP (Trans Membrane Pressure) and to optimize the membrane operation. When the membrane flux were operated at 70 LMH and 80 LMH under stable water quality conditions with an inlet turbidity of 10 NTU or less, the TMP increase rates were 0.28 and 0.24 kPa/d, respectively, with minor difference. When the membrane with high flux of 80 LMH was operated for a long time under inlet turbidity of 10 NTU or more, the TMP increase rate showed the maximum of 43.5 kPa/d. However, when the CEB(Chemically Enhanced Backwash) cycle was changed from 7 to 1 day, it was confirmed that the TMP increase rate was stable to 0.23 kPa/d. As a result of applying pre-treatment process(DAF) on unstability water quality conditions, it was confirmed that the TMP rise rates differed by 0.17 and 0.64 kPa/d according to the optimization of the coagulant injection. When combined with coagulation pretreatment, it was thought that the balance with the membrane process was more important than the emphasis on efficiency of the pretreatment process. It was considered that stable TMP can be maintained by optimizing the cleaning conditions when the stable or unstable water quality even in the high flux operation on membrane process.

• Tunnel and Underground Space
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• v.31 no.1
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• pp.41-51
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• 2021

The hydraulic fracturing developed to improve permeability of tight reservoir is one of key stimulation technologies for developing unconventional resources such as shale gas and deep geothermal energy. The experimental study was conducted to improve disadvantage of hydraulic fracturing which has simple fracture pattern and poor fracturing efficiency. The fracturing experiments was conducted for tight rock using various fracturing fluids, water, N2, and CO2 and the created fracture pattern and fracturing efficiency was analyzed depending on fracturing fluids. The borehole pressure increased rapidly and then made fractures for hydraulic fracturing with constant injection rate, however, gas fracturing shows slowly increased pressure and less fracture pressure. The 3D tomography technic was used to generate images of induced fracture using hydraulic and gas fracturing. The stimulated reservoir volume (SRV) was estimated increment of 5.71% (water), 12.72% (N2), and 43.82% (CO2) respectively compared to initial pore volume. In addition, permeability measurement was carried out before and after fracturing experiments and the enhanced permeability by gas fracturing showed higher than hydraulic fracturing. The fracture conductivity was measured by increasing confining stress to consider newly creating fracture and closing induced fracture right after fracturing. When the confining stress was increased from 2MPa to 10MPa, the initial permeability was decreased by 89% (N2) and 50% (CO2) respectively. This study shows that the gas fracturing makes more permeability enhancement and less reduction of induced fracture conductivity than hydraulic fracturing.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.99-107
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• 2018

This research has developed a high temperature steam cleaning technology using a ceramic membrane with durability against temperature and pressure conditions. In steam cleaning, steam of $120^{\circ}C$ is injected into the ceramic membrane to induce pyrolysis by the endothermic reaction to remove fouling from the membrane. The water quality of raw water was adjusted to turbidity 10, 25 NTU and DOC 2.5 mg/L, and the membrane was uniformly fouled by constant pressure operation at 100, 200, and 300 kPa. Physical backwashing was performed with water and air at a pressure of 500 kPa and steam at $120^{\circ}C$ was injected for 0 to 5 minutes. As the turbidity concentration and the operating pressure increased, the flux decreased by 0.7 to 14.4%. It is confirmed that 10.7 to 53.8% recovery is possible than physical cleaning at the injection of steam for 3 minutes, so it is considered that the steam cleaning of the ceramic membrane is effective. Compared with CEB after NaOCl (300 mg/L) filtration at 25 NTU and 300 kPa of turbidity, the steam cleaning result for 3 minutes was similar to 46.7% of CEB for 3 hours. It has been confirmed that steam cleaning is suitable for a ceramic membrane having excellent heat resistance against high temperature. It was considered to have better cleaning efficiency as compared with general physical backwashing.