• Korean Journal of Food Science and Technology
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• v.53 no.4
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• pp.365-374
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• 2021

In this study, the effect of enzyme-modified starch used in the preparation of filled hydrogel powder loaded with curcumin (FHP) on redispersibility, thermal and UV stability, and curcumin retention during in vitro digestion was investigated. FHP maintained stability without layer separation when redispersed and showed more stability against UVB than the emulsion powder (EMP). There was no significant difference in the chemical stability of curcumin between rice starch-based filled hydrogel powder (RS-FHP) and enzyme-modified starch-based filled hydrogel powder (GS-FHP). However, the gel matrix of GS-FHP maintained greater stability of lipid droplets in the stomach compared to RS-FHP, thereby improving the retention rate of curcumin after in vitro digestion. GS-FHP could be used as a novel material for developing premixes that require stable formulation and maintenance of functional substances, as it can increase the dispersion stability and retention rate of functional substances after digestion.

• Membrane Journal
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• v.29 no.1
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• pp.51-60
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• 2019

In order to improve gas separation properties of polymeric membranes which have been widely applied in the industry field, aluminosilicate hollow nanoparticles named as allophanes were synthesized by sol-gel method and formulated in Poly(dimethylsiloxane) (PDMS) matrix to investigate the gas separation properties of PDMS membrane. Transmission electron microscope (TEM), Energy dispersive X-ray analysis (EDX), X-ray diffractometer (XRD), Surface area and pore size analyzer (BET) and Fourier transform infrared spectrophotometer (FTIR) were carried out to characterize the synthetic allophanes. Then the PDMS mixed matrix membranes were prepared by adding different volume fraction of allophanes. To examine the effect of allophanes addition in PDMS matrix using unmodified allophane and modified ones, the gas permeation experiments were performed using oxygen, nitrogen, methane and carbon dioxide. As the volume fraction of modified allophane increased up to 4.05 Vol% the permeability of four test gases through PDMS mixed matrix membranes increased. Also, the selectivity of $O_2/N_2$ and $CO_2/CH_4$ increased with the contents of the modified allophane. Further improvement of gas separation properties of PDMS mixed matrix membranes containing higher volume percent of allophanes can be expected as long as well dispersion of allophanes in PDMS matrix can be achieved for better PDMS membranes.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.714-722
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• 2019

Catalysts were prepared by using incipient wetness impregnation method with 17 wt% Ni on a support ($SiO_2-Y_2O_3$, $Al_2O_3$, $SiO_2-ZrO_2$, $SiO_2$, $TiO_2$, MgO) and the catalytic activity in the reductive amination of ethanol with ammonia in the presence of hydrogen was compared and evaluated. The catalysts used before and after the reaction were characterized using X-ray diffraction, nitrogen adsorption, ethanol-temperature programmed desorption (EtOH-TPD), isopropanol-temperature programmed desorption (IPA-TPD), and hydrogen chemisorption etc. In the case of preparing $ZrO_2$ and $Y_2O_3$ supports, the small amount of Si dissolution from the Pyrex reactor surface provoked the formation of mixed oxides $SiO_2-ZrO_2$ and $SiO_2-Y_2O_3$. Among the catalysts used, $Ni/SiO_2-Y_2O_3$ catalyst showed the best activity, and this good activity was closely related to the highest nickel dispersion, and low desorption temperature in EtOH-TPD and IPA-TPD. The low catalytic activity on Ni/MgO catalysts showed low activity due to the formation of NiO-MgO solid-solutions. In the case of $Ni/TiO_2$, the reactivity was low due to the low nickel metal phase due to strong metal-support interaction. In the case of using a support as $SiO_2-Y_2O_3$, $Al_2O_3$, $SiO_2-ZrO_2$, and $SiO_2$, the selectivities of ethylamines and acetonitrile were not significantly different at similar ethanol conversion.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.497-504
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• 2019

We fabricated $HfO_2$ thin films using RF magnetron sputtering method, and investigated structural and optical properties of $HfO_2$ thin films with RTA temperatures in $N_2$ ambient. $HfO_2$ thin films exhibited polycrystalline structure regardless of annealing process, FWHM of M (-111) showed reduction trend. The surface roughness showed the smallest of 3.454 nm at a annealing temperature of $600^{\circ}C$ in result of AFM. All $HfO_2$ thin films showed the transmittance of about 80% in visible light range. By fitting the refractive index from the transmittance and reflectance to the Sellmeir dispersion relation, we can predict the refractive index of the $HfO_2$ thin film according to the wavelength. The $HfO_2$ thin film annealed at $600^{\circ}C$ exhibited a high refractive index of 2.0223 (${\lambda}=632nm$) and an excellent packing factor of 0.963.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.102-112
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• 2019

This paper studies impact fracture behavior under temperature variation and compressive flexural strength of cement composites using VAE(vinyl acetate ethylene) powder polymer and PVA(polyvinyl alcohol) fiber. Impact test were conducted in the temperature range selected for the $-35^{\circ}C$, $0^{\circ}C$ and $35^{\circ}C$. In this experimental study, impact test were carried out using a drop impact testing machine (Ceast 9350) to obtain such as displacement, time, and impact fracture energy of normal specimen and and cement composites specimen. As test results, the use of VAE powder polymer and PVA fiber were observed to enhance the flexural strength of mortar. The compressive strength of PVA fibers reinforced cement composites was slightly decreased at 28 days, but the flexural strength was observed to increase 24.4% of normal mortar strength. As a result of the drop impact tests, PVA fiber reinforced cement composites specimens showed microcracks due to energy dispersion and crack prevention with bridge effect of the fibers, and scabbing or perforation by impact was suppressed. On the other hand, the normal mortar and VAE powder polymer cement composites specimens were carried out to the perforation and macro crack. Most of normal mortar and the cement composites subjected to impact load on specimens shows mostly local brittle failure. The impact resistant performance of the specimen with PVA fiber was greatly improved due to the increase of flexure performance.

• The Journal of the Korea Contents Association
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• v.19 no.5
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• pp.280-286
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• 2019

This study first examines whether the matching principle reduces information asymmetry and verifies the effect on earnings sustainability and information asymmetry. In the presence of information asymmetry between managers and information users, managers can reduce information asymmetry by increasing the quality of earnings. Information asymmetry is measured by the financial analysts' earnings forecast variance. When we look at the results of previous studies, verify whether information asymmetry decreases as the response to the revenue cost increases and whether negative relationship between profit persistence and information asymmetry appears when the response to the revenue cost is high. As a result, firms with high revenue cost response showed a decrease in information asymmetry. The persistence of the earningss from the high earnings-cost response shows that the analysts' earnings forecast dispersion decreases. This means that the better the response to the revenue cost, the better the quality of the earnings and the less the information risk about the uncertainty of the enterprise. This study is different from the previous studies in that it analyzed whether the persistence of the earnings that responded to the high revenue cost reduces the information asymmetry. The results of this study suggest that managers can reduce the information asymmetry by carrying out appropriate revenue - cost responses, which provides important implications for stakeholders who use accounting earnings information.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.413-419
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• 2019

In the recent, as a world demand of energy resources has been transformed from fossil fuels to hydrogen-based clean energy resources, a huge attention has been attracted to increase the performance and decrease a production cost of core materials in fuel cell technology. The utilization of reinforced composite membranes as electrolytes in the polymer electrolyte membrane fuel cells can reduce the use of high cost perfluorosulfonic acid (PFSA), mitigate the cell impedance, and improve the dimensional stability as well as the interfacial stability, giving rise to achieve both an improved performance and a reduction of production costs of the fuel cell devices. In this study, we investigate the effects of physical characteristics and cell performances according to the various ionomer solvents in the solution based manufacturing process of reinforced composite electrolyte membrane.

• Journal of the Korean Geotechnical Society
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• v.37 no.2
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• pp.5-17
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• 2021

The Moon has been an attractive planet as an outpost for deep space exploration since He-3 and water ice which can be used as energy resources were discovered. In-Situ Resource Utilization (ISRU) construction material fabrication method is required for sustainable space planet exploration. In this paper, the possibility of microwave sintering technology for construction material fabrication was evaluated using lunar regolith that can be easily collected from the Moon surface. Experimental assessment of the influence factors on microwave sintering was conducted using a hybrid sintering system for efficient processing. The heat distribution in the furnace was observed using thermal paper that is coated with a material formulated to change color when exposed to heat. Based on this result, sintered cylindrical KLS-1s with a diameter of 1 cm and a height of 2 cm were fabricated. Densities were measured for the sintered KLS-1s under rotating turntable conditions that have an effect of microwave dispersion. The more dielectrics were arranged, the more microwaves were dispersed reducing the heat concentration, and thus a uniformity of sintered KLS-1s was enhanced.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.167-172
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• 2011

In this work, the effect of surface treatment on mesoporous carbons (MCs) supports was investigated by analyzing surface functional groups. MCs were prepared by a conventional templating method using mesoporous silica (SBA-15) for using catalyst supports in direct methanol fuel cells (DMFCs). The MCs were treated with different phosphoric acid ($H_3PO_4$) concentrations i.e., 0, 1, 3, 4, and 5 M at 343 K for 6 h. And then Pt-Ru was deposited onto surface treated MCs (H-MCs) by chemical reduction method. The characteristics of Pt-Ru catalysts deposited onto H-MCs were determined by specific surface area and pore size analyzer, X-ray diffraction, X-ray photoelectron, transmission electron microscopy, and inductive coupled plasma-mass spectrometer. The electrochemical properties of Pt-Ru/H-MCs catalysts were also analyzed by cyclic voltammetry experiments. From the results of surface analysis, an oxygen functional group was introduced to the surface of carbon supports. From the results, the H4M-MCs carbon supports surface treated with 4 M $H_3PO_4$ led to uniform dispersion of Pt-Ru onto H4M-MCs, resulting in enhancing the electro-catalytic activity of Pt-Ru catalysts.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.6
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• pp.47-54
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• 2020

The acupressure is a treatment that applies pressure to certain parts of the body and has been mainly used for pain relief in the field of oriental medicine. However, the treatment effect is often different depending on the practitioner's ability, experience, and physical strength, so standardized acupressure is needed. In this regard, the equipment is being released, but this is mainly a rolling massage method, which reduces energy concentration and poses a risk of injury. Therefore, in this study, a device that provides vertical acupressure based on variable bogie (wheel truck) was implemented. As a result of experimenting with load and body pressure distribution and desirability to validate the device's bearing pressure, the acupressure rod held up to 150kg, the body pressure ratio was measured lower than the body pressure ratio of the comparison item in section 0%