• Bulletin of the Korean Chemical Society
• /
• v.27 no.6
• /
• pp.936-938
• /
• 2006

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.50 no.3
• /
• pp.289-299
• /
• 2024

Chrysanthemum lucidum (C. lucidum), a perennial herb in the Asteraceae family, is an endemic species found only on Ulleung island in Gyeongsangbuk-do, South Korea. Previous studies have reported that the extract of C. lucidum exhibits excellent antioxidant activity due to its high polyphenol and flavonoid content. However, the anti-aging effects of C. lucidum extract, such as wrinkle improvement and cell regeneration, are not well known, and there has been no research on the activity of C. lucidum-derived extracellular vesicles (ClDEVs). Therefore, this study aimed to verify the anti-aging effects of ClDEVs through in vitro and clinical analyses. In cell experiments, ClDEVs promoted cell regeneration, increased the expression of COL1A1, a gene involved in collagen synthesis, and enhanced the expression of FLG and LOR, a biomarker related to skin barrier improvement. Additionally, ClDEVs suppressed the expression of aging-related biomarkers, such as the CDKN2A (encodes p16) and TP53 (encodes p53) genes, in cells induced to age. In a human clinical trial, after using a cosmetic product containing ClDEVs for 4 weeks, significant improvement in wrinkles around the eyes and nasolabial folds was observed. In conclusion, ClDEVs have demonstrated high potential as a bio-cosmetic ingredient for wrinkle improvement and anti-aging.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.22 no.1
• /
• pp.66-71
• /
• 2018

The evaluation of the shelf-life of energetic materials is important. However, there are several difficulties associated with the evaluation. First, aging experiments require a considerable amount of time. Second, treating highly energetic materials is dangerous. For these reasons, many evaluation methods have been developed. Because most energetic materials decompose with the evolution of heat, it is important to analyze the thermal properties of energetic materials in order to understand decomposition and aging properties. In this paper, we describe the estimation of thermal aging properties and develop a kinetic model from spot data set of mechanical properties and estimate aging properties for mechanical results.

• Korean Journal of Materials Research
• /
• v.29 no.6
• /
• pp.392-397
• /
• 2019

A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061 three-layer clad sheet. Two AA6061 and one AA5052 sheets of 2 mm thickness, 40 mm width, and 300 mm length are stacked, with the AA5052 sheet located in the center. After surface treatment such as degreasing and wire brushing, sample is reduced to a thickness of 1.5 mm by multi-pass cold rolling. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at rolling speed of 6.0 m/sec. The roll bonded AA6061/AA5052/AA6061 complex sheet is then hardened by natural aging(T4) and artificial aging(T6) treatments. The microstructures of the as-roll bonded and age-hardened Al complex sheets are revealed by optical microscopy; the mechanical properties are investigated by tensile testing and hardness testing. After rolling, the roll-bonded AA6061/AA5052/AA6061 sheets show a typical deformation structure in which grains are elongated in the rolling direction. However, after T4 and T6 aging treatment, there is a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 sheets. The as roll-bonded specimen shows a sandwich structure in which an AA5052 sheet is inserted into two AA6061 sheets with higher hardness. However, after T4 and T6 aging treatment, there is a different sandwich structure in which the hardness of the upper and lower layers of the AA6061 sheets is higher than that of the center of the AA5052 sheet. The strength values of the T4 and T6 age-treated specimens are found to increase by 1.3 and 1.4 times, respectively, compared to that value of the starting material.

• Korean Journal of Materials Research
• /
• v.32 no.3
• /
• pp.161-167
• /
• 2022

A cold roll-bonding process is applied to fabricate an AA6061/AA5052/AA6061/AA5052 layered sheet. Two AA6061 and one AA5052 sheets of 2mm thickness, 40mm width and 300mm length are alternately stacked, then reduced to a thickness of 2.0 mm by multi-pass cold rolling after surface treatment such as degreasing and wire brushing. The rolling is performed at ambient temperature without lubricant using a 2-high mill with a roll diameter of 400 mm at a rolling speed of 6.0 m/sec. The roll-bonded AA6061/AA5052/AA6061/AA5052 layered sheet is then hardened by natural aging (T4) and artificial aging (T6) treatments. The microstructure of the as-roll bonded and the age-hardened Al sheets was revealed by SEM observation; the mechanical properties were investigated by tensile testing and hardness testing. After T4 and T6 aging treatment, the specimens had a recrystallization structure consisting of coarse equiaxed grains in both AA5052 and AA6061 regions. The as-roll-bonded specimen showed a clad structure in which the hardness of AA5052 regions was higher than that of AA6061 regions. However, after T4 and T6 aging treatment, specimens exhibited different structures, with hardness of AA6061 regions higher than that of AA5052 regions. Strengths of T6 and T4 age-treated specimens were found to increase by 1.55 and 1.36 times, respectively, compared to the value of the starting material.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.26 no.4
• /
• pp.28-43
• /
• 2022

To minimize such loss due to aging, research on energetic materials is being actively conducted though, there are difficulties in identifying the comprehensive aging mechanisms as they focused on the respective materials. In this study, thermal and surface analysis were performed on energetic materials composed of metals(W, Ti, and Zr) and KClO₄ oxidizer to solve the blind spots of this aging study. It was newly found that the metals in the hygrothermally aged compounds can cause significant changes in performance. For example, the growth in the thickness of the oxide film on the metals led to an increase in the average value of activation energy(E_α). In addition, the standard deviation of E_α tends to dependent on the type of metal, which is due to the difference in electronegativity.

• Korean Journal of Materials Research
• /
• v.33 no.12
• /
• pp.565-571
• /
• 2023

AA1050/AA6061/AA1050 layered sheet was fabricated by cold roll-bonding process and subsequently T4 and T6 aging-treated. Two commercial AA1050 sheets of 1 mm thickness and one AA6061 sheet of 2 mm thickness were stacked up so that an AA6061 sheet was located between two AA1050 sheets. After surface treatments such as degreasing and wire brushing, they were then roll-bonded to a thickness of 2 mm by cold rolling. The roll-bonded Al sheets were then processed by natural aging (T4) and artificial aging (T6) treatments. The as roll-bonded Al sheets showed a typical deformation structure, where the grains are elongated in the rolling direction. However, after the T4 and T6 aging treatments, the Al sheets had a recrystallized structure consisting of coarse grains in both the AA5052 and AA6061 regions with different grain sizes in each. In addition, the sheets showed an inhomogeneous hardness distribution in the thickness direction, with higher hardness in AA6061 than in AA1050 after the T4 and T6 age treatments. The tensile strength of the T6-treated specimen was higher than that of the T4-treated one. However, the strength-ductility balance was much better in the T4-treated specimen than the T6-treated one. The tensile properties of the Al sheets fabricated in the present study were compared with those in a previous study.

• Industry Promotion Research
• /
• v.9 no.2
• /
• pp.115-125
• /
• 2024

The increase in the elderly population and growing interest in skin beauty, alongside specialized scientific examination of natural substances, have led to a rise in the utilization of natural materials. This paper investigates the types of natural substances, the functionality of extracts, and extraction technologies based on the literature that utilizes natural ingredients to mitigate skin aging. To directly assess the impact of functional materials derived from natural products on skin aging mitigation, the functionality of the extracts was determined based on their ability to synthesize Procollagen and reduce MMP-1. Each natural product is categorized into plants, herbal medicines, and microalgae in the literature utilizing the above evaluation methods. This paper describes the extraction technologies for securing functional materials from each ingredient and the main outcomes, providing trends in research on extraction technologies for functional materials aimed at alleviating skin aging

• Korean Journal of Materials Research
• /
• v.25 no.9
• /
• pp.468-474
• /
• 2015

Evaluations of the microstructure and mechanical properties of age hardenable Cu-2.0wt%Be alloy are performed in order to determine whether it can be used as a welding electrode for projection welding. The microstructure examinations, hardness measurements, and tensile tests of selective aging conditions are conducted. The results indicate that the aging treatment with the fine-grained microstructure exhibits better hardness and high tensile properties than those of the coarse-grained microstructure. The highest hardness value and high tensile strength are obtained from the aged condition of $300^{\circ}C$ for 360 min due to the presence of the metastable ${\dot{\gamma}}$ precipitates on the grain boundaries. The values of the highest hardness and tensile strength are measured as 374 Hv and 1236.2 MPa, respectively. The metastable ${\dot{\gamma}}$ precipitates are transferred to the equilibrium ${\gamma}$ precipitates due to the over-aged treatment. The presence of the ${\gamma}$ precipitates appears as nodule-like precipitates decorated around the grain boundaries. The welding electrode with the best aging treated condition exhibits better welding performance for electrodes than those of electrodes used previously.

• Carbon letters
• /
• v.28
• /
• pp.9-15
• /
• 2018

In the aerospace field, Carbon/Cork composites have been used for rocket propulsion systems as a light weight structural component with a high bending stiffness and high thermal insulation properties. For the fabrication of a carbon composite with a heat insulation cork part, the bonding properties between them are very important to determine the service life of the Carbon/Cork composite structure. In this study, the changes in the interfacial adhesion and mechanical properties of Carbon/Cork composites under accelerated aging conditions were investigated. The accelerated aging experiments were performed with different temperatures and humidity conditions. The properties of the aged Carbon/Cork composites were evaluated mainly with the interfacial strength. Finally, the lifetime prediction of the Carbon/Cork composites was performed with the long-term property data under accelerated conditions.