• 한국축산식품학회지
• /
• 제31권6호
• /
• pp.799-806
• /
• 2011

This study was conducted to evaluate the effect of the aging period prior to freezing on the meat quality of Hanwoo longissimus dorsi (LD) muscle. Three different combinations of aging and freezing periods (0/90, 20/70, and 40/50) were examined using LD muscle at 24 h postmortem under an identical storage time of 90 d. The pH and lightness slightly increased with increasing aging period. However, there were no significant (p>0.05) differences in redness and yellowness. The solitary freezing treatment (0/90) had the significantly (p<0.05) lowest moisture content. The un-aged treatment had a significantly (p<0.05) higher total loss than the aged treatments due to an increase in thaw drip loss. The aging significantly improved the myofibrillar fragmentation index and shear force of Hanwoo LD muscle (p<0.05). In addition, the aged treatments produced a higher flavor, tenderness, juiciness, and overall acceptability relative to un-aged treatment. However, there was no significant (p>0.05) difference in shear force and sensorial properties between 20 and 40 d aging prior to freezing. Therefore, 20 d aging prior to freezing may be a sufficiently effective strategy to improve the tenderness and sensorial properties of Hanwoo LD muscle.

• 한국압력기기공학회 논문집
• /
• 제13권1호
• /
• pp.92-100
• /
• 2017

Due to the presence of ferrite phase in the finished welds, austenitic stainless steel welds (ASSWs) are considered susceptible to the thermal aging embrittlement during long-term service in light water reactor environment. In this study, the thermal aging embrittlement of typical ASSWs, E308 and ER316L welds, were evaluated after the long-term exposure up to 20,000 h at $400^{\circ}C$, which is considered as an accelerated thermal aging condition. After thermal aging, the decrease of tensile ductility and fracture toughness was observed. The microstructure observation with high resolution transmission electron microscopy revealed that spinodal decomposition in ferrite phase of both E308 and ER316L welds would be the main cause of the degradation of mechanical properties. Also, it was shown that the difference of thermal ageing embrittlement between ER316L and E308 welds was significant, such that the reduction of fracture resistance for ER316L weld was much larger than that of E308 weld.

• 대한금속재료학회지
• /
• 제49권3호
• /
• pp.197-202
• /
• 2011

This study was carried out to investigate the precipitation behavior of ${\chi}$ phase and effect of ${\chi}-phase$ which precipitated at the initial stage of aging on mechanical properties of 25%Cr-7%Ni-4%Mo-0.2%N super duplex stainless steel. ${\chi}-phase$ was precipitated mainly at the interface of ferrite / austenite phases and inside of the ferrite phase at the initial stage of aging, and it was transformed into ${\sigma}-phase$ with an increase of aging time. The ferrite phase was decomposed into new $austenite({\gamma}_2)phase$ and ${\sigma}-phase$ by aging treatment. The hardness and tensile strength of the initial stage of aging when ${\chi}-phase$ was precipitated did not changed considerably, while elongation rapidly decreased. Accordingly, it is considered that ${\chi}-phase$ didn't affect the hardness and strength significantly, but it affected the elongation.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제45권1호
• /
• pp.1-11
• /
• 2022

Silkworm pupae, a by-product of the silk industry are known to be valuable resource of nutrients for humans as well as animals besides encompassing diverse bioactive constituents. However, there is a paucity of knowledge on their role in amelioration of oxidative stress and anti-skin aging properties. In the present study, we evaluated the inhibitory effect of aqueous as well as ethanolic (30% and 70%) extracts from distinct stages of male and female silkworm pupae belonging to two silkworm varieties on skin aging-related enzymes. The activities of collagenase, elastase and tyrosinase were effectively inhibited by 70% ethanolic silkworm pupal extracts (SPE), followed by 30% with aqueous extracts exhibiting meager inhibitory potential. SPE were also investigated for their antioxidant activity in oxidative-stressed murine fibroblasts (L929). The intracellular ROS and lipid peroxidation induced by tert-butyl hydroperoxide (t-BHP) in fibroblasts was better attenuated by pre treatment with ethanolic (30%) and aqueous extracts, respectively. The safety of the extracts was determined by studying their effect on fibroblast cell viability and it was found that none of the extracts were cytotoxic. Our findings indicate the potential utility of SPE as anti-aging components in cosmeceuticals.

• 한국수산과학회지
• /
• 제56권6호
• /
• pp.833-840
• /
• 2023

In this study, the antioxidant and anti-skin aging properties of the Korean marine algae Ishige foliacea were investigated. Solvent extracts from I. foliacea were prepared with 70% ethanol, 80% methanol, and water. The extraction yields of various solvent extracts ranged from 9.55% to 35.12%. In terms of antioxidant activity, the ethanol extract showed the highest ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) radical scavenging activity, nitrite oxide scavenging activity, reducing power, and FRAP (ferric reducing antioxidant power). Regarding anti-skin aging activity, evaluation of the skin whitening and anti-wrinkle activities revealed that the methanol, water, and ethanol extracts possessed the highest tyrosinase (IC₅₀=0.98 mg/mL), elastase (IC₅₀=0.15 mg/mL), and collagenase (IC₅₀=0.06 mg/mL) inhibitory activities, respectively. These results suggest that I. foliacea holds potential as an antioxidant and anti-skin aging substance in food and cosmetic materials.

• 한국축산식품학회지
• /
• 제43권5호
• /
• pp.901-913
• /
• 2023

This study aimed to investigate changes in the quality of meat aged using Jeju scoria earthenware. Water-holding properties, pH, color, tenderization, fatty acid composition, and free amino acid characteristics of aged pork loin were evaluated to determine the effects of wet and dry (normal and Jeju Scoria) aging methods and aging time (0, 10, 20, 30, and 40 days) on meat quality. The aging methods altered pH and CIE L^* after 10 days of aging. However, the aging method did not alter the pH and CIE L^* of the aged pork loin after 10 days of aging. The shear force was significantly lower in the Scoria aging method than in the wet aging method after 10 and 20 days of aging. Both the normal and Scoria aging methods increased aging loss compared to the wet aging method, which could be attributed to longer air exposure times of the two non-packaged aging methods than in the packaged aging method. The scoria aging method had significantly higher contents and ratios of saturated (SFA) to mono-unsaturated fatty acids but lower ratios of poly-unsaturated fatty acids to SFA than the wet aging method. The content of most free amino acids significantly increased with aging time, especially those related to the sweet, and umami categories. In summary, this study suggests that the Scoria aging method provides positive aspects of eating quality, such as improvement of meat tenderness and taste, including umami, with minimum changes in the overall meat quality.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 추계학술대회 논문집
• /
• pp.313-316
• /
• 2008

This work sought to examine the suitability of twin roll strip casting for Ag-27%Cu-25%Zn-3%Sn brazing alloy (BAg-7A) and to investigate the mechanical properties and microstructure of the strip. The effect of aging heat treatment on the properties was also studied,. This new manufacturing process has applications in the production of the brazing alloy. XRD and microstructural analysis of the Ag-27%Cu-25%Zn-3%Sn strip represented eutectic microstructure of a Cu-rich phase and a Ag-rich matrix regardless of heat treatment. The results of mechanical tests showed tensile strength of 470MPa, a significant enhancement, and an 18% elongation of the twin roll casted strip, due mainly to the solid solution strengthening of Zn atoms (${\sim}20%$) in the Cu-rich phases. Tensile results showed gradually decreasing strengths and increasing elongation with aging heat treatment. Microstructural evolution and fractography were also investigated and related to the mechanical properties.

• 한국전기전자재료학회논문지
• /
• 제18권10호
• /
• pp.917-923
• /
• 2005

In this paper, effect of catalytic configuration on the sensing properties of $SnO_2$ nanoparticle gas sensitive thick film was investigated. Two types of catalytic configuration, mono and binary, were made on the $SnO_2$ nanoparticle. In case of mono catalytic system, $3 wt\%$ Pd or Pt catalyst was doped onto the $SnO_2$ nanoparticle, respectively. In case of binary catalytic system, Pd and Pt was doped simultaneously with concentration ratio of 1:2 to 2:1 onto the $SnO_2$ nanoparticle. After doping, gas sensitive thick film was printed on alumina substrate and heat-treated at 450 to $600^{\circ}C$. Gas sensing properties was evaluated using 500 to 10,000 ppm $CH_4$ gas. As a result, gas sensitive thick film with binary catalytic system showed unstable phenomena that the gas sensitivity was changed according to aging time. In contrary, the mono catalytic system showed relatively stable phenomena despite of aging time. Especially, gas sensitive thick film doped with $3 wt\%$ Pt catalyst and heat-treated at $500^{\circ}C$ showed good sensing properties such as 0.57 of $R_{3500}/R_{1000}$ and very small variation within $3.5\%$ after aging for 5 hours, and response time was very short less than 20 seconds.

• 한국전기전자재료학회논문지
• /
• 제16권12호
• /
• pp.1071-1076
• /
• 2003

The nonlinear properties and their stability of ZPCCD- based varistors, which are composed of ZnO P $r_{6}$ $O_{ll}$ - CoO-C $r_2$ $O_3$-D $y_2$ $O_3$-based ceramics, were investigated in the D $y_2$ $O_3$ content range of 0.0∼2.0 mol%. The incorporation of D $y_2$ $O_3$ greatly affected the nonlinear properties and the best nonlinearity was obtained from 0.5 mol% D $y_2$ $O_3$ with nonlinear exponent of 66.6 and leakage current of 1.2 $\mu$A. Further addition of D $y_2$ $O_3$ deteriorated the nonlinear properties. In stability against DC accelerated aging stress state: 0.95 $V_{1mA}$/15$0^{\circ}C$/24 h, the 0.5 mol％ D $y_2$ $O_3$-doped varistor exhibited the highest stability, in which the variation rate of varistor voltage and nonlinear exponent are -1.9% and 10.5%, respectively. The remainder varistors resulted in thermal runaway due to low density of ceramics.s.s.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집A
• /
• pp.143-148
• /
• 2001

This research was undertaken to clarify effects of thermal aging on electrochemical and mechanical properties of superaustenitic stainless steel. The steel was artificially aged at $300{\sim}650^{\circ}C$ for $240{\sim}10,000hrs$. and investigated at $-196{\sim}650^{\circ}C$ using small punch(SP) test. Also, the change in electrochemical properties caused by effects of thermal aging was investigated using electrochemical anodic polarization test in a KOH electrolyte. Carbides and ${\eta}-phase(Fe_2Mo)$ precipitated in the grain bounderies seem to deteriorate the mechanical properties by decreasing cohesive strength in the grain bounderies and promote the current density observed in electrochemical polarization curves. The electrochemical and mechanical properties of superaustenitic stainless steel was drastically decreased in the specimen aged at $650^{\circ}C$.