• Applied Chemistry for Engineering
• /
• v.31 no.6
• /
• pp.630-634
• /
• 2020

We developed a processing recipe to synthesize flexible polyurethane foam with a pore size of 335 ± 107 ㎛. The gelling reaction time was varied from 0 to 30 minutes and the physical properties of the foam were evaluated. The gelling reaction where the polypropylene glycol and tolylene 2,4-diisocyanate (TDI) were reacted to form urethane prepolymer, proceeded until a chemical blowing agent, deionized water, was introduced. Fourier transform infrared (FT-IR) spectra showed that the composition of the foam did not change but the foam height reached a peak value when the gelling reaction time was 10 minutes. We found that increasing the gelling time lessened the coalescence and helped the formation of cells. Lastly, the repeatability of polyurethane foam was confirmed by one-way analysis of variance (ANOVA) by synthesizing ten identical polyurethane foams under the same experimental conditions, including the gelling reaction time. Overall, the new time parameter in-between the gelling and blowing reactions will give extra stability in manufacturing identical polyurethane foams and can be applied to various polyurethane foam processes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.644-650
• /
• 2021

This study characterized the reforming of methane with carbon dioxide, which is a major cause of global warming. The methane decomposition reaction with carbon dioxide was carried out using transition metal catalysts. The reactivity of tin was lower than that of a transition metal, such as nickel and iron. Most of the decomposition reaction occurred in the solid state. The melting point of tin is 505.03 K. Tin reacts in a liquid phase at the reaction temperature and has the advantage of separating carbon produced by the decomposition of methane from the liquid tin catalyst. Therefore, deactivation due to the deposition of carbon in the liquid tin can be prevented. Methane decomposition with carbon dioxide produced carbon monoxide and hydrogen. Ni was used to promote the catalyst performance and enhance the activity of the catalyst and lifetime. In this study, catalysts were synthesized using the excess wet impregnation method. The effect of the reaction temperature, space velocity was measured to calculate the activity of catalysts, such as the activation energy and regeneration of catalysts. The carbon-deposited tin catalyst regeneration temperature was 1023 K. The reactivity was improved using a nickel co-catalyst and a water supply.

• Journal of the Korean GEO-environmental Society
• /
• v.12 no.12
• /
• pp.63-70
• /
• 2011

Expanded Polystyrene (EPS) is a type of geosynthetic material manufactured with various strengths, unit weights, and dimensions. Due to recent advances in research on EPS, the use of EPS has increased dramatically. This super light weight material has a unit weight of approximately $0.16{\sim}0.47kN/m^3$, equivalent to 6.3~15.7 of that of most natural soils with conditions of fill materials. In spite of this advantage, it is noted that no standard method of resilient modulus test on EPS geofoam was reported and no literature on resilient modulus test methods for EPS geofoam exist. The main object of this study was to investigate feasibility of the resilient modulus of EPS when it was applied for flexible pavement. The investigation of the feasibility was completed based on the results from triaxial tests.

• Journal of Convergence for Information Technology
• /
• v.12 no.1
• /
• pp.144-152
• /
• 2022

The Spartina anglica is recognized as a highly invasive plant and active eradication methods are required. In this study, we aimed to determine the physiologic activities of Spartina anglica extracts as a cosmetic ingredient. Antioxidant properties were investigated by different chemical methods including radical quenching (DPPH and ABTS), reducing power(FRAP) assay and aerial part of S. anglica(SAA) extract presented the strongest antioxidant activities. The significant cytotoxicity was not observed up to a concentration of 0.5 mg/mL in RAW264.7 cells and NHDF cells. The anti-inflammatory activity of S. anglica belowground(SAB) extract had strong effects on cell-based systems, including LPS-induced NO and cytokines(TNF-a and IL-6) production in RAW264.7 cells. Collagen synthesis and skin hydration gene expression of S. anglica extract showed the highest anti-wrinkle and moisturizing effect in NHDF cells. Results presented in this study tend to show that the ethanol extracts of S. anglica could be exploited as useful-bio-resource for bioactive substances in functional cosmetics.

• Journal of the Microelectronics and Packaging Society
• /
• v.29 no.1
• /
• pp.17-33
• /
• 2022

Ti₃C₂T_X MXene, first reported by Naguib et al. in 2011, has attracted tremendous attention due to its excellent hydrophilicity, electrical conductivity, and mechanical/chemical stability. Since MXene is a two-dimensional material with a thickness of few nanometers, which ensure its flexibility. In last few years, due to these properties many researchers used Ti₃C₂T_X MXene into various fields such as flexible smart sensors, energy harvesting/storage devices, supercapacitors and electromagnetic interference shielding systems. In this review article, we have briefly discussed the various synthesis processes and characteristics of Ti₃C₂T_X MXene. Moreover, we reviewed the latest development of Ti₃C₂T_X MXene as flexible electrode material to be used into different applications.

• Korean Journal of Materials Research
• /
• v.32 no.1
• /
• pp.14-22
• /
• 2022

To improve light absorption ability in the visible light region and the efficiency of the charge transfer reaction, Pd nanoparticles decorated with reduced TiO₂ nanotube photocatalyst were synthesized. The reduced TiO₂ nanotube photocatalyst was fabricated by anodic oxidation of Ti plate, followed by an electrochemical reduction process using applied cathodic potential. For TiO₂ photocatalyst electrochemically reduced using an applied voltage of -1.3 V for 10 min, 38% of Ti⁴⁺ ions on TiO₂ surface were converted to Ti³⁺ ion. The formation of Ti³⁺ species leads to the decrease in the band gap energy, resulting in an increase in the light absorption ability in the visible range. To obtain better photocatalytic efficiency, Pd nanoparticles were decorated through photoreduction process on the surface of reduced TiO₂ nanotube photocatalyst (r10-TNT). The Pd nanoparticles decorated with reduced TiO₂ nanotube photocatalyst exhibited enhanced photocurrent response, and high efficiency and rate constant for aniline blue degradation; these were ascribed to the synergistic effect of the new electronic state of the TiO₂ band gap energy induced by formation of Ti³⁺ species on TiO₂, and by improvement of the charge transfer reaction.

• Korean Journal of Food Science and Technology
• /
• v.54 no.4
• /
• pp.369-376
• /
• 2022

This study was conducted to investigate the efficacy of rose hip utilization on various diseases. Rose hips are produced on a shrub native to Europe, and have been used for medicinal purposes and nutritional supplementation for centuries. It is rich in minerals, vitamins, and various functional compounds, including calcium, magnesium, phosphorus, potassium, selenium, vitamin B, vitamin C, and vitamin E, quercetin, catechin, β-carotene, β-sitosterol, polyphenol, flavonoid, taxifolin, ellagic acid, and salicylic acid. Extracts and powders of rose hips have been reported to contain antioxidant, free radical scavenging, and anti-inflammatory activity, and exert beneficial effects including amelioration of osteoarthritis, body fat reduction, anti-obesity activity, anti-bacterial activity, antidiabetic properties, and anti-cancer activity. Therefore, rose hips as a functional natural food may be considered effective for use in treating diseases including obesity, diabetes, osteoporosis, cardiovascular disease, and cancer.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.12
• /
• pp.1797-1808
• /
• 2021

Artificial intelligence is considered one of the core technologies leading the 4th industrial revolution. It is adopted in various fields bringing about a huge paradigm shift throughout our society. The field of biotechnology is no exception. It is undergoing innovative development by converging with other disciplines such as computers, electricity, electronics, and so on. In drug discovery and development, big data-based AI technology has a great potential of improving the efficiency and quality of drug development, rapidly advancing to overcome the limitations in the existing drug development process. AI technology is to be specialized and developed for the purpose including clinical efficacy and safety-related end points based on the multidisciplinary knowledge such as biology, chemistry, toxicology, pharmacokinetics, etc. In this paper, we review the current status of AI technology applied for drug discovery and consider its limitations and future direction.

• Membrane Journal
• /
• v.33 no.4
• /
• pp.168-180
• /
• 2023

H₂ generation from renewable sources is crucial for ensuring sustainable production of energy. One approach to achieve this goal is biohydrogen production by utilizing renewable resources such as biomass and microorganisms. In contrast to commercial methods, biohydrogen production needs ambient temperature and pressure, thereby requiring less energy and cost. Biohydrogen production can reduce greenhouse gas emissions, particularly the emission of carbon dioxide (CO₂). However, it is also associated with significant challenges, including low hydrogen yields, hydrodynamic issues in bioreactors, and the need for H₂ separation and purification methods to obtain high-purity H₂. Various technologies have been developed for hydrogen separation and purification, including cryogenic distillation, pressure-swing adsorption, absorption, and membrane technology. This review addresses important experimental developments in dense polymeric membranes for biohydrogen purification.

• Journal of the Korean Society of Radiology
• /
• v.17 no.4
• /
• pp.531-539
• /
• 2023

Self-absorption is the most important factor affecting the accuracy of gamma spectroscopy measurements in environmental samples. In particular, it is affected by other factors such as the chemical composition of the sample, geometric shape, thickness, density, atomic number, distance between the sample and detector, energy of the emitted gamma photon, and humidity coefficient or percentage in the sample. To test the calibration method, a 450 ml CRM standard source (9 nuclide) Marinelli beaker was used. Five soil samples among environmental samples were measured by density by applying the corrected values. Therefore, it can be seen that the self-absorption value is more effective for somewhat large and low photon energy. In the case of environmental samples, it was confirmed that the overall energy peak efficiency through self-absorption of the source greatly depends on the density of the sample.