High-entropy alloys (HEAs) are characterized by having five or more main elements and forming simple solids without forming intermetallic compounds, owing to the high entropy effect. HEAs with these characteristics are being researched as structural materials for extreme environments. Conventional refractory alloys have excellent hightemperature strength and stability; however, problems occur when they are used extensively in a high-temperature environment, leading to reduced fatigue properties due to oxidation or a limited service life. In contrast, refractory entropy alloys, which provide refractory properties to entropy alloys, can address these issues and improve the hightemperature stability of the alloy through phase control when designed based on existing refractory alloy elements. Refractory high-entropy alloys require sufficient milling time while in the process of mechanical alloying because of the brittleness of the added elements. Consequently, the high-energy milling process must be optimized because of the possibility of contamination of the alloyed powder during prolonged milling. In this study, we investigated the hightemperature oxidation behavior of refractory high-entropy alloys while optimizing the milling time.

In this study, we performed thermal safety design of the electric module of a heat-loaded equipment with consideration of its heat dissipation performance. Initially, we calculated the heat dissipation of natural convection to choose a cooling method. Based on this, we found that some modules required forced convection and selected an air-cooling method with an outdoor temperature of 43 degrees Celsius, which is the maximum temperature in Korea. Prior to module production, we performed thermal analysis of each module and proceeded with a design to increase the thermal conductivity of the module as a primary step, and subsequently proceeded with Heat Sink design to maximize the heat dissipation performance. After considering various constraints according to the system requirements and designing the cooling path, we experimentally and analytically secured thermal safety at the operating temperature of the equipment.

In this study, when stem cell culture solution is used as a cosmetic ingredient, one of the most prominent problems is that the ingredients generally have low thermal stability. Therefore, in this study, in order to find out how the stem cell culture medium is heated or preserved at high temperature, the effect of various effects of stem cells on the various effects of the stem cells was investigated. Investigated. As a result of the experiment, the wound healing assay confirmed that the cell migration increased after 6 hours, and after 24 hours, it was confirmed that the cell mobility was increased and cell division was promoted, thereby being concentrated. As a result of investigating the amount of transdermal water loss by preparing a cosmetic product containing stem cell culture solution, it was confirmed that the culture solution addition group showed an improvement rate of 31% compared to the non-added group, thereby helping in skin wound recovery. As a result of this, it is considered that this point should be considered when the stem cell culture medium is used as an active ingredient in cosmetics in the future.

Ti0.5Al0.5N/CrN nano-multilayers, which are known to exhibit excellent wear resistances, were prepared using the unbalanced magnetron sputter for various periods of 2–7 nm. Ti0.5Al0.5N and CrN comprised a cubic structure in a single layer with different lattice parameters; however, Ti0.5Al0.5N/CrN exhibited a cubic structure with the same lattice parameters that formed the superlattice in the nano-multilayers. The Ti0.5Al0.5/CrN multilayer with a period of 5.0 nm exceeded the hardness of the Ti0.5Al0.5N/CrN single layer, attaining a value of 36 GPa. According to the low-angle X-ray diffraction, the Ti0.5Al0.5N/CrN multilayer maintained its as-coated structure up to 700oC and exhibited a hardness of 32 GPa. The thickness of the oxidation layer of the Ti0.5Al0.5N/CrN multilayered coating was less than 25% of that of the single layers. Thus, the Ti0.5Al0.5N/CrN multilayered coating was superior in terms of hardness and oxidation resistance as compared to its constituent single layers.

Cycloamyloses (CA) from high-amylose rice starch (Dodamssal, 50.94% amylose) was produced to form a complex with anthocyanin extracted from black rice (sihtoheukmi). The effects of CA concentration (1, 5, 10 and 30%, w/v), pH (2, 4, 6, and 8), UVB irradiation time (~24h) and thermal treatment time (~24h) on the oxidant capacity of the complex were investigated. Anthocyanin consisting of 95% cyanidin-3-glucoside (C3G) was extracted from the black rice by suspending in 60%(v/v) ethanol containing 0.2%(v/v) hydrochloric acid for 90 min at 50°C. Cycloamyloses (CA) produced by 4-α-glucanotransferase (4αGTase) formed complexes with C3G by shaking the mixture for 48 hours at 30°C. Antioxidant activities (radical scavenging capacity) were determined by using ABTS [2,2'-azinobis-(3-ethylbenzothiazoline- 6-sulfonic acid)]. The antioxidant activities of the complexes increased with pH increasing. Upon UVB irradiation and heat treatment, the antioxidant activities were more retained for the complexes incorporating 10% CA concentration or above compared to the C3G control. Degradation rate constant (Kd) and half-life (T1/2) were obtained from degradation data of CA complex with cyanidin-3-glucoside. The effect of CA complex formation with C3G is significantly observed at pH4. The results suggest that the CA complex formed with C3G indeed has an enhanced antioxidant potential toward UVB and thermal degradation.

Carbohydrate derivatives of cyanidin, a class of anthocyanin pigments, are major component of red cabbage, which is responsible for the characteristic reddish color. The color of cyanidin derivatives is quite stable against heat, and here we aimed to identify the chemical component of glucoside-derivatives of cyanidin which is responsible for the thermal stability. By comparing the thermal stability of color from unmodified cyanidin and cyanidin-3,5-diglucoside with the color of cyanidin derivatives from red cabbage, we found that the glucoside modification confers the thermal stability. We believe that our finding will contribute to the preparation of heat-resistant anthocyanin pigments for food coloring and other applications.

This work attempted to fabricate organic/inorganic nanocomposite by combining organic cellulose nanofibrils (CNFs), isolated by 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation of native cellulose with inorganic nanoclay. The morphology and dimension of CNFs, and tensile properties and thermal stability of CNF/clay nanocomposites were characterized by transmission electron microscope (TEM), tensile test, and thermogravimetry (TG), respectively. TEM observation showed that CNFs were fibrillated structure with a diameter of about 4.86±1.341 nm. Tensile strength and modulus of the hybrid nanocomposite decreased as the clay content of the nanocomposite increased, indicating a poor dispersion of CNFs or inefficient stress transfer between the CNFs and clay. The elongation at break increased at 1% clay level and then continuously decreased as the clay content increased, suggesting increased brittleness. Analysis of TG and derivative thermogravimetry (DTG) curves of the nanocomposites identified two thermal degradation peak temperatures (Tp1 and Tp2), which suggested thermal decomposition of the nanocomposites to be a two steps-process. We think that Tp1 values from 219.6℃ to 235℃ resulted from the sodium carboxylate groups in the CNFs, and that Tp2 values from 267℃ to 273.5℃ were mainly responsible for the thermal decomposition of crystalline cellulose in the nanocomposite. An increase in the clay level of the CNF/clay nanocomposite predominately affected Tp2 values, which continuously increased as the clay content increased. These results indicate that the addition of clay improved thermal stability of the CNF/clay nanocomposite but at the expense of nanocomposite’s tensile properties.

Camellia sinensis L. (green tea) seed oils were prepared by roasting at 213℃ and pressing (RP), pressing (P), and nhexane extraction (H). The physico-chemical properties of the RP, P, and H samples, including fatty acid composition, color, and sensory characteristics were analyzed. RP, P and H samples were thermally oxidized at 180℃, and oxidative stability was determined by DPPH, CDA, and p-AV at 0, 20, 40, 60, and 80 min. Compared to the P and H samples, RP resulted in significantly higher thermal oxidative stability according to the DPPH, CDA, and p-AV results (p〈0.05). The ratio of unsaturated fatty acids to saturated fatty acids among RP, P, and H samples were significantly different (p〈0.05). The oleic acid and linoleic acid contents in green tea seed oils were 58 and 23%, respectively. Hunter's color value of lightness (L) for the RP, P, and H samples was not significant. Redness (a) of RP was 3.47±0.119 and yellowness (b) of H was 60.10±2.483, which were significantly different. Compared to RP samples, H and P samples had the highest color and off-odor values in the sensory evaluation. RP samples showed the highest taste value and were significant overall (p〈0.05). The thermal stability of RP extraction was more stable than any other method. Camellia sinensis L. seed oil extracted by RP had better sensory characteristics than other edible oils, including soybean oil, grape seed oil, and extra virgin olive oil.

Zinc soap and Zn/Ba mixed metal soap were synthesized and PVC plastisol with mixed metal soap and various costabilizers were also synthesized with good structures and characterized by IR and 1H-NMR. The IR spectrums and 1H-NMR spectrums of the synthesized soaps were in very good accordance with the structures proposed by earlier workers. In using phosphite as a costabilizer, TIDP phosphite was shown to be the excellent thermal stabilization effect at the low temperature and TNPP phosphite was shown to be the excellent thermal stabilization effect at the high temperature. In case of antioxidant, it was revealed that antioxidant was not effective in the low temperature thermal stabilization effect while highly effective in the high temperature thermal stability. NaClO4 solution with sorbitol solvent had the best thermal stabilization effect among NaClO4 solution series at low and high temperature.

Metal(Zinc) soap and mixed metal(Zn/Ba) soap were synthesized with good structures and characterized by IR and H-NMR. The H-NMR spectrums of the synthesized soaps were in very good accordance with the structures proposed by earlier workers. The mixed metal soaps with various costabilizers(acid or metal content effect), which added in order to investigate the thermal stabilization effect at low and high temperature, were investigated the thermal stabilization effect. The temperature effect is relation to the metal content effect than acid effect. In case of mixed metal soap, the high thermal stabilization effect improved with increasing Barium content. As the Zinc content increase the low temperature thermal stabilization effect improved, but the high temperature thermal stabilization effect showed an opposite tendency.

The thermal stability and mechanical properties of Nephila clavata and Bassaniana decorata spider silks were measured and compared with those of aramid and polyester fibers. The thermal stability of the spider silk was lower than those of the commercial aramid and polyester fibers. However, the mechanical properties of the spider silk were far superior to that of the polyester fiber. The effect of the water content of the spider silk on its thermal stability and mechanical property was examined by conducting the silk to heat treatment at 100℃ under vacuum for various times. The results indicated that spider silk subjected to heat treatment for 1.5 hr had excellent thermal stability and mechanical property.

In order to improve the thermal stability of PAN-based electrospun fibers, AP-PER-MEL and TiO2 were added in to the fibers as additives. The polymer composite with uniformly mixed additional agents was obtained. In case of non-treated sample, the fibers were burn off completely with high rate within 620℃. But in case of treated samples (EF-M and EF-MT), it is sure that the thermal stability was improved by studying TGA data and ISO flammability test about 20 and 30%, respectively. A synergy effect of adding two kinds of agents (AP-PER-MEL and TiO2) into PAN-based electrospun fibers was confirmed. Through SEM images, it is confirmed that the fiber shape can be kept even after addition of agents (AP-PER-MEL and TiO2). Finally the thermal stability of fibers was largely developed with keeping the nature of PAN-based fibers effectively.

This paper describes the experiments for investigating the effects of thermal stability of several commercial carpet mate materials. The melting point and thermal decomposition temperature was measured by means of a differential scanning calorimeter(DSC) in air condition. The DSC data and burning test results of nylon bulked continuous filament(N-BCF) yarn 100%, nylon(NY), polypropylene(PP), and a new material named polytrimethyleneterephthalate(PTT) were analysed to obtain the effect on their thermal stability. Conclusively, we observed that PTT and PP were approximately 380℃ and 240℃ to start the thermal decomposition, respectively. In other words, PTT is thermally the most stable material for carpet manufacturing.