• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.247-253
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• 2019

3D printing technology has attracted considerable attention because of its potential to fabricate the intricate design of ceramic products. In this study, ceramic 3D nozzle printing was introduced to manufacture complex alumina products with a ceramic pigment. The alumina paste was formulated by incorporating an elastomer to impart viscoelastic properties. Viscoelastic pastes play an essential role in ceramic 3D nozzle printing. The effects of the viscoelastic properties of the ceramic pastes on their printability were assessed using comprehensive rheological analysis, and various shapes were printed. As a result, the paste with a high yield stress showed better printability. In addition, a ceramic pigment was added to the developed pastes to increase the aesthetics of the printed ceramic structure. The printed ceramic parts were sintered in air at 1300 ℃. The stability of the ceramic pigment was confirmed even after high-temperature sintering.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.518-525
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• 2018

In the 21st century, human beings are becoming increasingly concerned about greenhouse gas emissions as the environment changes due to climate change become serious. The temperature of Korea has risen by approximately $1.5^{\circ}C$ from 1904 to 2000, and the climate is changing gradually to a subtropical climate. As a result, the frequency of floods and droughts increases, so that the water available to humans is decreasing every year, and the cost of using city water is rising every year. The reuse of wastewater that is normally abandoned is inevitable. This study examined the monthly data for 6 months of operation by installing a reuse system of concentrated wastewater (Re R/O System) that is generated during the process of manufacturing de-ionized water (DI-Water System) used in semiconductor processing. As a result of the survey, the city water supply saved approximately $2,767m^3$ per month. The average annual greenhouse gas emissions was $1,329.07kg-CO_2$ per month due to the electricity consumption of the water reuse system. On the other hand, because of the reduction in city water supply, the average monthly average of $918.64kg-CO_2$ was reduced, and the greenhouse gas emissions were increased to $410.43kg-CO_2$ per month. If it improves some processes in the water reuse system, the amount of greenhouse gas emissions can be reduced by an average of $254.41kg-CO_2$ per month.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.474-481
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• 2018

The policy-making and technological development of eco-friendly automobiles designed to increase their supply is ongoing, but the internal combustion engine still accounts for approximately 95% of automobiles in use. To meet the stricter emission regulations of internal combustion engines based on fossil fuels, the proportion of after-treatments for vehicles and (ocean going) vessels is increasing continuously. As diesel engines have high power and good fuel economy in addition to less CO2 emissions, their market share is increasing not only in commercial vehicles, but also in passenger cars. Because of the characteristics of the diesel combustion, however, NOx is generated in localized high-temperature combustion regions, and particulates are formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for the after-treatment of exhaust gas to reduce NOx in diesel vehicles. This study examined the effect of a containing promoter on SCR catalysts to cope with the severe exhaust gas regulation. The de-NOx performance of the Mn-SCR catalyst was the best, and the de-NOx performance was improved as the ion exchange rate between Mn ion and Zeolyst was good and the activation energy was low. The de-NOx performance of the 7Cu-15Ba/78Zeoyst catalyst was 32% at $200^{\circ}C$ and 30% at $500^{\circ}C$, and showed the highest performance. The NOx storage material of BaO loaded as a promoter was well dispersed in the Cu-SCR catalyst and the additional de-NOx performance of BaO was affected by the reduction reaction of the Cu-SCR catalyst. Among the three catalysts, the 7Cu-15Ba/Zeolyst SCR catalyst was resistant to thermal degradation. The same type of CuO due to thermal degradation migrates and agglomerates because BaO reduces the agglomeration of the main catalyst CuO particles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.380-389
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• 2020

The conversion characteristics and fuel properties for producing biodiesel (BD) by blending beef-tallow, an animal waste resource with a high-saturated fatty acid content, and sunflower-oil, a vegetable oil with a high-unsaturated fatty acid content, were investigated. For this investigation, the effects of the control factors, such as the oil-blend ratio and methanol-to-oil molar ratio, on the fatty acid methyl ester and BD production yield were also investigated. The kinematic viscosity reduction effects of BD using heating and ultrasonic irradiation were verified, and the optimal temperature of each BD-diesel fuel blend for reducing the kinematic viscosity was derived using the correlation equation. As a result, the optimal conditions for producing blended biodiesel were verified to be TASU7 and a methanol-to-oil molar ratio of 10:1. The analysis results of the fuel properties of TASU7 satisfied the BD quality standard; hence, the viability of BD blended with waste tallow as fuel was verified. The experimental results on the kinematic viscosity reduction showed that heating is more effective in reducing the kinematic viscosity because it took less time than ultrasonic irradiation, and the equipment was cheaper and more straightforward than the ultrasonic irradiation method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.596-601
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• 2020

Silicon carbide is considered a potentially useful material for high-temperature electronic devices because of its large band gap energy and p-type or n-type conduction that can be controlled by impurity doping. Accordingly, the thermoelectric properties of -SiC powder prepared by refined diatomite were investigated for high value-added applications of natural diatomite. -SiC powder was synthesized by a carbothermal reduction of the SiO₂ in refined diatomite using carbon black. An acid-treatment process was then performed to eliminate the remaining impurities (Fe, Ca, etc.). n-Type semiconductors were fabricated by sintering the pressed powder at 2000℃ for 1~5h in an N2 atmosphere. The electrical conductivity increased with increasing sintering time, which might be due to an increase in carrier concentration and improvement in grain-to-grain connectivity. The carrier compensation effect caused by the remaining acceptor impurities (Al, etc.) in the obtained -SiC had a deleterious influence on the electrical conductivity. The absolute value of the Seebeck coefficient increased with increasing sintering time, which might be due to a decrease in the stacking fault density accompanied by grain or crystallite growth. On the other hand, the power factor, which reflects the thermoelectric conversion efficiency of the present work, was slightly lower than that of the porous SiC semiconductors fabricated by conventional high-purity -SiC powder, it can be stated that the thermoelectric properties could be improved further by precise control of an acid-treatment process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.575-581
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• 2020

A colorless antistatic agent was prepared for use in antistatic films for liquid crystal displays (LCDs) requiring low surface resistance and high transmittance. Among various lithium-fluoro compounds and quaternary ammonium salts, antistatic materials were selected based on their electrical conductivity, and antistatic agents were prepared to measure the surface resistance. As a result, the material with high conductivity showed a relatively low surface resistance, i.e., relatively good antistatic performance. Based on the antistatic materials selected, the formulation ratio for producing the best antistatic agent was established through the experimental design method and the effects of each factor were analyzed. The higher the use of lithium- fluoro compounds as antistatic materials, the higher the ratio of oligomer use with multi-functional groups, and the smaller the surface resistance. The quaternary ammonium salts increased the antistatic performance of the lithium-fluoro compounds, but the effects of the amount used were not relatively large. After manufacturing the antistatic PET film, the properties of the antistatic film showed low surface resistance values (<10⁹ Ω/sq.), high permeability (>92%), low haze (<0.5%), and high whiteness (L^⁎>95). In addition, the antistatic film reliability was found to be excellent by showing a stable surface-resistance change rate of less than 10%, even under high temperature and high humidity conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.304-311
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• 2020

The purpose of this study is to change plant growth according to the light quantity of LED light source and to standardize plant factories technology according to the optimal LED light range. Growth was relatively stable at the 1,400 lx and 1,600 lx intensities, and growth continued with increasing light intensity, but growth slowed down with growth without leaves (Ed- I don't understand). The growth characteristics at 400 lx to 800 lx were sustained to some extent during the experimental period, but the growth of the larvae was maintained until the 7th day and the growth of leaves was not developed. From 1,000 lx to 1,400 lx, brightness, leaf growth and daily growth increased, and the growth cycle exhibited a repeating cycle of growth and slowdown. In addition, 1,600 lx and 1,800 lx showed similar growth to that at 1,400 lx, but leaf growth was high. However, at 1,800 lx, the growth was slightly higher than at 1,400lx and it slowed down over time. In addition, the stronger the light, the higher the temperature around the plant and the greater the dryness of the leaves due to the heat emitted from the light source.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.293-299
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• 2020

This study was undertaken to optimize combining the processes of enzymatic hydrolysis and extraction for lycopene production from autumn olive berry. The autumn olive berry was pulverized and suspended in water, followed by treatment with various hydrolytic enzymes including Ceremix, Celluclast, AMG, Viscozyme, Pectinex, Promozyme, Ultraflo and Tunicase. Reaction solutions were subjected to extraction by applying different organic solvents including acetone, ethyl acetate, hexane and chloroform. Highest yields of lycopene extraction were obtained with the Ceremix (hydrolysis enzyme) and chloroform (extraction solvent) combination. Subsequently, using this ideal combination, enzymatic hydrolysis conditions, including enzyme concentration, pH and temperature, were statistically optimized to 0.58%, 5.5 and 54.4℃, respectively, by applying the response surface method. The lycopene extraction yield increased 2.3-fold (22.6 mg/100g) by using the selected combined process. We propose that these results could be used for the future development of bioactive materials required for bio-health care products.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.164-172
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• 2020

The fuel oil/heat exchanger installed in military aircraft is a device that cools the lubricant oil supplied to other devices, such as an AMAD, and a hydraulic pump using the low temperature of the fuel is cracked at the AMAD lubricant inlet port. If a crack in the heat exchanger occurs, the lubricant oil supplied to other equipment is not cooled. Therefore, the flight can no longer be performed. In this study, non-destructive inspection and microscopic examination of the fracture surface of the oil port were performed to analyze the crack tendency. The oil pipe connected to the oil port is a titanium pipe, which is fastened with over torque and has been identified as the leading cause of heat exchanger oil port cracks. In addition, it was verified as the main reason for cracking by finite element analysis. The material and diameter of the pipe were changed to improve this defect, and the applied torque was adjusted. In addition, the bending value of the pipe was adjusted to minimize the fatigue accumulation due to pulsating pressure. As a result, no cracks occurred on the heat exchanger via the ground test after the installation of an improved pipe under the same conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.57-63
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• 2020

To develop simple acrosome staining of horse spermatozoa, this study tested the binding properties of Coomassie brilliant blue G or R on the sperm smears after 3.7% paraformaldehyde (PF) or 35% methanol (MT) fixation. After being fixed with PF and stained with 0.05, 0.1, or 0.2 % of CBB G or R for 2 min, horse spermatozoa were examined for their intact acrosome status. The intact acrosome of fresh horse spermatozoa were 62.6% and 61.5% with 0.05% of the G and R CBB solution, but 80.2 and 79.7% with G type and 78.1 and 76.0% with R type. On the other hand, when MT was used for fixation, the acrosome reacting sperm ratio was 3.5%, but was 9.0% in the case of PF. These results show that the intact acrosome of horse sperm could be judged using a 0.1~0.2% CBB G or R staining technique. PF would be an essential fixative for examining acrosome reacting horse spermatozoa. This method could be used to identify sperm with a damaged acrosome during low-temperature storage or cryopreservation for artificial insemination of horses.