• Resources Recycling
• /
• v.31 no.6
• /
• pp.60-65
• /
• 2022

This study presents the carburization process for recycling sludge, which was formed during silicon wafer machining. The sludge used in the carburization process is a mixture of silicon and silicon carbide (SiC) with iron as an impurity, which originates from the machine. Additionally, the sludge contains cutting oil, a fluid with high viscosity. Therefore, the sludge was dried before carburization to remove organic matter. The dried sludge was washed by acid cleaning to remove the iron impurity and subsequently carburized by heat treatment under vacuum to form the SiC powder. The ratio of silicon to SiC in the sludge was varied depending on the sources and thus carbon content was adjusted by the ratio. With increasing SiC content, the carbon content required for SiC formation increased. It was demonstrated that substoichiometric SiC_x (x<1) was easily formed when the carbon content was insufficient. Therefore, excess carbon is required to obtain a pure SiC phase. Moreover, size reduction by high-energy milling had a beneficial effect on the suppression of SiC_x, forming the pure SiC phase.

• Journal of the Korean Society of Radiology
• /
• v.17 no.6
• /
• pp.957-964
• /
• 2023

This study focused on hand sanitizer as a medium that can replace ultrasonic gel, which is vulnerable to contamination by bacteria that reside on the hand. Hand sanitizer produces a strong sterilization effect from germs resident on the hands through different sterilization principles depending on the ingredients. Select products of gel type, cream type, and foam type, except for liquid type with low viscosity, and ultrasonically apply one 62% ethanol gel type and one cream type, one benzalkonium chloride 0.066% cream type and one foam type, respectively. Using ATS-539 as a medium, image evaluation was performed on the axial and lateral resolution and penetration depth, and the presence or absence of an air layer between the probe and the phantom. As a result, in the evaluation of the axial and lateral resolution and the depth of penetration, all four experimental groups met the evaluation criteria. However, in the case of the foam type, although it was suitable for the evaluation criteria of resolution and penetration depth, dark shadows appeared on both sides except for the center of observation during image evaluation. Through this experiment, it was possible to confirm the possibility that the remaining three types of hand sanitizers except the foam type could replace the ultrasonic gel.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.30 no.1
• /
• pp.63-72
• /
• 2024

Poly (butylene adipate-co-terephthalate) (PBAT) is one of the representative biodegradable polymers with high ductility and processability to replace petroleum-based polymers. Many investigations have been conducted to broaden the applications of PBAT in a variety of industries, including the food packaging, agricultural mulching film, and logistics and distribution fields. Foaming process is widely known technique to generate the cell structure within the polymer matrix, offering the insulation and light weight properties. However, there was no commercially feasible foam product based on biodegradable polymers, especially PBAT, and maintaining a proper melt viscosity of the polymer would be a key parameter for the foaming process. In this study, chemical foaming agent and cross-linking agent were introduced to PBAT, and a compression molding process was applied to prepare a foam sheet. The correlation between cell morphological structures and mechanical and physical properties was evaluated. It was found that PBAT with foam structures effectively reduced the density and thermal conductivity, allowing them to be suitable for applications such as insulation and lightweight packaging or cushion materials.

• Food Science and Preservation
• /
• v.30 no.1
• /
• pp.122-131
• /
• 2023

Persimmon peels are mostly discared as a by-product of dried persimmon manufacturing, but effective use is required as it contains various functional constituents. This study covers the preparation of carotenoid-enriched oil by ultrasound treatment of persimmon peel in soybean oil solvent, and the investigation of its physicochemical characteristics. Using the Box-Behnken design and response surface methodology, the optimal extraction conditions (temperature, 62℃; time, 32 min; and persimmon peel to oil ratio, 1:3.1) were determined based on the carotenoid concentration of the extract. The physicochemical characteristics of the extract obtained under optimal conditions and the untreated soybean oil (control) were compared. The total carotenoid content of the extract increased. The carotenoid-enriched soybean oils had a lighter color than the controls, but with high redness and yellowness values. The effect of sonication and a component of the persimmon peel on the oxidation and heating stability of soybean oil was weak. The viscosity and activation energy of carotenoid-enriched soybean oil were slightly higher than those of the control. Thus, it was possible to prepare yellow-red carotenoid-enriched soybean oil by applying ultrasonic-soybean oil solvent extraction to persimmon peel. The oil is expected to be useful as an additive as well as a substitute for general edible oils.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.33 no.4
• /
• pp.653-660
• /
• 2006

Fuji VII is a glass-ionomer cement specially targeted for early protection in erupting first and second molars. Properties of Fuji VII such as very high level of fluoride release, low viscosity and no need to preliminarily etch the substrate would be useful to erupting molars with primary pit and fissure caries or hypoplastic area for preventive goal or remineralization. The purpose of this study were to evaluate remineralization of Fuji VII glass ionomer cement and to compare with one of other restorative materials such as conventional glass ionomer cement, resin-modified glass ionomer cement, compomer and composite resin. Forty-two extracted human molars were used for this study. All teeth were immersed in demineralizing solution for 48 hours after Class V cavity preparation was made on sound proximal surface. The teeth were randomly divided into six groups and restored with Fuji VII, Fuji II, Fuji II LC improved, F2000, $Filtek^{TM}$ Z250 and control group was unrestored. The middle area with $130{\pm}20{\mu}m$ thickness was separated from specimen using microtome and demineralized area was photographed under polarized microscope. Separated area was relocated to specimen and stored in artificial saliva, After four weeks, changes of demineralized area were observed and compared to them restorated immediately. The results from the this study can be summarized as follows ; 1. Fuji VII, Fuji II, Fuji II LC improved have more prominent remineralization effect than F2000, $Filtek^{TM}$ Z250, control group. 2. No significant differences in remineralization effect are seen between Fuji VII and Fuji II, Fuji II LC improved.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.48 no.1
• /
• pp.55-64
• /
• 2022

The potassium cream soap with fatty acid called cleaning foam has a crystal gel structure, and unlike an emulsion system, it is weak to shear stress and shows characteristics that are easily separated under high temperature storage conditions. The crystal gel structure of cleansing foams is significantly influenced by the nature and proportion of fatty acids, degree of neutralization, and the nature and proportion of polyols. In order to investigate the effect of these parameters on the crystal gel structure, a ternary system consisting of water/KOH/fatty acid was investigated in this study. The investigation of differential scanning calorimeter (DSC) revealed that the eutectic point was found at the ratio of myristic acid (MA) : stearic acid (SA) = 3 : 1 and ternary systems were the most stable at the eutectic point. However, the increase in fatty acid content had little effect on stability. On the basis of viscosity and polarized optical microscopy (POM) measurements, the optimum degree of neutralization was found to be about 75%. The system was stable when the melting point (T_m) of the ternary system was higher than the storage temperature and the crystal phase was transferred to lamellar gel phase, but the increase in fatty acid content had little effect on stability. The addition of polyols to the ternary system played an important role in changing the T_m and causing phase transition. The structure of the cleansing foams were confirmed through cryogenic scanning electron microscope (Cryo-SEM), small and wide angle X-ray scattering (SAXS and WAXS) analysis. Since butylene glycol (BG), propylene glycol (PG), and dipropylene glycol (DPG) lowered the T_m and hindered the lamellar gel formation, they were unsuitable for the formation of stable cleansing foam. In contrast, glycerin, PEG-400, and sorbitol increased the T_m, and facilitated the formation of lamellar gel phase, which led to a stable ternary system. Glycerin was found to be the most optimal agent to prepare a cleansing foam with enhanced stability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.12
• /
• pp.496-503
• /
• 2016

To analyze an infinite slope that is reinforced with stabilizing piles, the forces on the stabilizing pile were estimated by the theory of plastic deformation and the theory of plastic flow and the effects of diverse factors on the factor of safety of an infinite slope were investigated. According to the results of the analyses, the factor of the safety of the slope reinforced with stabilized piles were increased tremendously and the factor of safety decreased as the center to center distance of the stabilizing pile increased. The effect of the existence of seepage of the infinite slope with stabilizing piles on the factor of safety appears to be insignificant. Considering the formulated factor of safety of an infinite slope with stabilizing piles, the width and length of the element of the infinite slope and force on the stabilizing pile influence the factor of safety of the infinite slope with a stabilizing pile including the soil strength parameter, inclination of the slope and depth of the slope, which are important for calculating the factor of safety of a non-reinforced infinite slope. The factor of safety of an infinite slope with stabilizing piles derived from the theory of plastic deformation were increased significantly with the internal friction angle of the soil, and the minimum and the maximum factor of safety under the conditions considered in this study were 13.7 and 65.6, respectively. As the diameter of the stabilizing pile increased, the forces on the stabilizing pile also increased but the factor of safety of the infinite slope with stabilizing piles decreased due to the effects of the width and the length of the element of the infinite slope. The factor of safety of the infinite slope with stabilizing piles derived from plastic flow were much larger than that of the non-reinforced infinite slope and the factor safety of the infinite slope with a stabilizing pile increased with increasing product of the flow velocity and plastic viscosity ( ) and the factor of safety of the infinite slope with stabilizing piles decreased with increasing center to center distance of the pile.

• Korean Chemical Engineering Research
• /
• v.56 no.3
• /
• pp.309-314
• /
• 2018

In this study, methanol extracts of the Oxalidaceae were tested with a potential functional cosmetic agent. As cosmetic agent tests, cell toxicity, polyphenol content, antioxidation, anti-wrinkle, and whitening effects were measured. Cell toxicity of the extracts was weak up to $1,000{\mu}g/mL$. Polyphenol contents of Oxalis corniculata L., Oxalis obtriangulata Maximowicz and Oxalis articulata Savigny were $116.036{\pm}0.37mg/g$, $54.72{\pm}0.52mg/g$ and $88.18{\pm}1.15mg/g$, respectively. Oxalis corniculata L., Oxalis obtriangulata Maximowicz and Oxalis articulata Savigny extracts showed 89%, 80% and 88% of antioxidation effects at $1,000{\mu}g/mL$ concentration using DPPH free radical scavenging assay. Oxalis corniculata L., Oxalis obtriangulata Maximowicz and Oxalis articulata Savigny extracts indicated 81%, 51% and 57% of antiwrinkle effects at $1,000{\mu}g/mL$ concentration using elastase inhibition assay. Oxalis corniculata L. extract was particularly excellent in elastase inhibition effect. Whitening effect using tyrosinase inhibition assay was relatively weak. Lotion formulation including 1% Oxalis obtriangulata Maximowicz extract was stable based on the temperature stability test for 28 days in terms of pH, viscosity and appearance. However, Lotion formulation including 1% Oxalis corniculata L. extract and Oxalis articulata Savigny extract need formulation improvement. From the research, methanol extract of Oxalis corniculata L. seems to be good candidate for antiwrinkle functional cosmetic agent.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.50 no.spc1
• /
• pp.29-32
• /
• 2005

This experiment aimed to estimate the effect of imperfect rice on rice palatability. Rice cultivar, Ilpumbyeo, was cultivated by direct-seeding on flooded paddy surface with 11 kg/10a nitrogen application. Palatability of harvested rice was measured by NIR spectroscope. Brown rice was divided according to their appearance namely, perfect, discolored, green-kerneled, and immature opaque with a composition ratio of $75.7\%,\;11.0\%,\;8.0\%,\;and\;5.3\%$ respectively. When the perfect brown rice was milled, the grain were composed of head, cracked, and white core & belly, at $64.7\%,\;25.3\%\;and\;10.0\%$ respectively. The milled rice of discolored brown rice had similar composition with the perfect rice. The milled green-kerneled vice, on the other hand, had $36\%$ head rice and $64\%$ white core & belly rice. The immature opaque brown rice, when milled, had $25.3\%$ white core & belly and $74.7\%$ damage & opaque rice. With the respect to grain quality, the viscosity of white core at belly rice and damaged & opaque rice was lower than that of head rice. In contrast, their protein content was a little higher than that of head rice. The palatability value of pure imperfect rice was much lower than head rice. The palatability value of damaged & opaque rice was the lowest among the imperfect rices. When mixed with head rice, the damaged & opaque rice impacted on the deterioration of vice palatability. Mixing $1\%$ each of white core at belly rice and damaged h opaque rice decreased the palatability value by $5\%$ as compared with the head rice.

• Radiation Oncology Journal
• /
• v.20 no.2
• /
• pp.147-154
• /
• 2002

Purpose : Gingko biloba extract (GBE), a natural product extracted from Gingko leaves, is known to increase the radiosensitivity of tumors. This radiosensitization probably arises from the increase in the peripheral blood flow by decreasing the blood viscosity and relaxing the vasospasm. The influence of a GBE on the metabolic status in fibrosarcoma II (FSall) of a C3H mouse was investigated using $^{31}P$ magnetic resonance spectroscopy (MRS). Materials and Methods : Eighteen C3H mice with fibrosarcoma II $(from\;100\;mm^3\;to\;130\;mm^3)$ were prepared for this experiment. The mice were divided into 2 groups; one (9 mice) without a priming dose, and the other (9 mice) with a priming dose of GBE. The GBE priming dose (100 mg/kg) was administered by an intraperitoneal (i.p.) injection 24 hours prior to the measurement. First $^{31}P$ MRS spectra were measured in the mice from each group as a baseline and test dose of GBE (100 mg/kg) was then administered to each group. One hour later, the $^{31}P$ MRS spectra were measured again to evaluate the change in the energy metabolic status. Results : In the group without the priming dose, the mean pH, PCr/Pi, PME/ATP, Pi/ATP, PCr/(Pi+PME) values 1 hour after the test dose were not changed significantly compared to the values at the baseline. However, in the group with the priming dose, the mean PCr/Pi, Pi/ATP, PCr/(Pi+PME) values 1 hour after the test dose changed from the baseline values of 0.49, 0.77, 0.17 to 0.74, 0.57, 0.28 respectively. According to the paired t-test, the differences were statistically significant. Conclusion : The above findings suggest that the metabolic status is significantly improved after administering GBE if the priming dose is given 24 hours earlier. This shows that the radiosensitizing effect of GBE is based on the increase of tumor blood flow and the improvement in the metabolic status.