• Journal of the Korean Society for Heat Treatment
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• v.35 no.5
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• pp.255-261
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• 2022

In this work, the strain-amplitude independent and strain-amplitude dependent damping capacities of Mg-5%Sn alloy have been investigated as a function of its age-hardening response. The hardness increased with an increase in aging time, reached a peak value after 48 h, and then it gradually decreased. The damping capacities of the Mg-5%Sn alloy exhibited a decreasing tendency in the order of solution-treated, under-aged, peakaged, and over-aged states in the strain-amplitude dependent region, whereas they increased continuously with aging time in the strain-amplitude independent region. The microstructural examination during aging revealed that the lower concentration of Sn solutes in the α-(Mg) matrix and the lower density of the Mg₂Sn precipitate particles may well be the crucial factors for better damping values in the strain-amplitude independent and strain-amplitude dependent regions, respectively.

• Elastomers and Composites
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• v.57 no.4
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• pp.165-174
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• 2022

The effect of fumed silica loading on the thermal stability and mechanical properties of fluorosilicone (FVMQ) rubber was investigated. The distribution of fumed silica inside FVMQ was characterized using scanning electron microscopy, and the thermal stability of composites was evaluated using thermogravimetric analysis and by the changes in mechanical performance during thermo-oxidative aging. The function mechanism of fumed silica was studied by Fourier transform infrared spectroscopy. The results show that with increasing silica content, the crosslink density of composites, the modulus at 100%, and tensile strength also increased, whereas the elongation at break decreased. Furthermore, increasing the silica content of composites increased the initial decomposition temperature (T_d) and residual weight of the composite after exposure to nitrogen. In addition, the thermal oxidative aging experiment demonstrated improved aging resistance of the FVMQ composites, including lower change in tensile strength, elongation at break, and modulus at 100%.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.271-277
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• 2013

Inconel 718 super alloy was aging heat treated at the temperature range from $675^{\circ}C$ to $785^{\circ}C$ for 5~40 hours after solution annealing at $1025^{\circ}C$ for 1 hour. The aging treated specimens were investigated microstructure, mechanical properties and thermal expansion/contraction. Precipitates appeared for a long time aging treatment were niobium carbide and also ${\gamma}^{\prime}$ phase. For the aging treatment time of 10 hours, the changes in strength and hardness with increasing aging treatment temperature showed the maximum value at the temperature of $725^{\circ}C$. This maximum value is to be related with the precipitation of ${\gamma}^{\prime}$ and ${\gamma}^{{\prime}{\prime}}$ phases. The decrease in strength, elongation and hardness during long time aging at $725^{\circ}C$ were thought to be induced from the coarsening of the grain size and the transformation of ${\gamma}^{{\prime}{\prime}}$ phase to ${\gamma}^{\prime}$ phase. For the specimens treated for 10 hours, impact energy showed constant value of ~105 J with increasing the aging temperature, however this value continuously decreased with elapsing time at the aging temperature of $725^{\circ}C$. It was found that the decrease in impact value was induced from the coarsening of grain size and the carbide coarsening. The coefficient of thermal expansion of aging treated Inconel 718 alloy increased with raising test temperature, and the coefficient was appeared $11.57{\sim}12.09{\mu}m/m{\cdot}^{\circ}C$ and $14.28{\sim}14.39{\mu}m/m{\cdot}^{\circ}C$, respectively, after heating to $150^{\circ}C$ and $450^{\circ}C$.

• Korean Journal of Environmental Agriculture
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• v.10 no.2
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• pp.149-157
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• 1991

In order to elucidate the possible change in the non-extractable bound residue of TCAB(3,3' 4,4' - tetrachloroazobenzene) in soil as a function of aging period, uniformly ring-labelled $^{14}C-TCAB$ was treated to soil(organic matter : 1.8%), and aged for 3, 6, 9, 12 and 15 months at $21{\pm}1^{\circ}C$, respectively. $^{14}CO_2$ evolution and volatilization loss during the aging were negligible. The amounts of non-extractable bound residue of TCAB increased gradually from 7.55% in 3-month aging to 19.32% in 15-month aging. Partition data suggested no formation of polar groups in the chemical structure of TCAB. Most of $^{14}C-radioactivity$ of bound residues was present in humin in the range of 50.52 to 58.93%. The fact that the number of microorganisms in soil decreased relative to the control suggested no chance of their involvement in the formation of non-extractable bound residues. Accordingly, the increase in the non-extractable bound residue of TCAB in soil with aging period is believed to be due to the transformation of the trans isomer to the cis one which is more polar and more adsorptive than the former.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.26-30
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• 2008

This study was conducted to identify the effect of chilling temperature (-3 and $6^{\circ}C$) and aging (1- and 7-day) on objective meat quality, collagen solubility, and free amino acids in pork (longissimus muscle of Yorkshire). Warner-Bratzler (WB)-shear force indicated that variation in chilling temperature had no detectable effect on meat tenderness and tenderization during the 7-day aging period. Among the 13 detected free amino acids, only 3 amino acids (histidine, valine, leucine) were significantly affected by the temperature treatment (p<0.05). Collagen solubility was significantly increased at $6^{\circ}C$ treatment (p<0.05). There was a significant linear relationship (r=0.67, p<0.05) between changes in free amino acids and WB-shear force during the 7-day aging period. These results confirmed that chilling conditions had significantly affected collagen solubility, and meat tenderization occurred in direct proportion to an increase in free amino acids.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.595-601
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• 2020

During the safety inspection of nitrocellulose-made explosive containers stored for more than 10 years, cracks were found in the containers. Therefore, a failure cause analysis test was performed. First, the cause of failure through the failure tree analysis was conducted to select the factors that influenced failure. The changes in the properties of the container caused by the acceleration of the reaction were found to be the cause of the failure by confirming the influence on the environment and internal/external factors that may occur during storage. To confirm this, environmental tests, such as thermal shock test and vacuum thermal stability test, were performed using a naturally aged container to analyze the cause of failure, and an accelerated aging test was performed to reproduce the failure. Through this, the chemical reaction was accelerated by heat and charge, as in the result of the fault tree analysis, and it was confirmed that the physical properties of the container were changed. In addition, the service life of the container was estimated using the Arrhenius model for the storage life due to thermal aging.

• Journal of Life Science
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• v.21 no.3
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• pp.464-467
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• 2011

Quercetin is a major flavonoid present in onions, which acts as an antioxidant. Quercetin exists both as a free compound and conjugated with carbohydrates, primarily as glucosides in onion. Aged black onion was made through a 30 day aging process in which the onions were kept in an environment of $60^{\circ}C$ and high humidity (90% RH). Quercetin and quercetin glucosides were assayed in onion bulbs before and after the aging process, using high performance liquid chromatography-electrospray ion trap mass spectrometry (HPLC-ESI/MS/MS). Quercetin mono- and diglucosides were identified in fresh onion bulbs, whereas quercetin aglycone was the only form present in aged black onion bulbs. These findings indicate that the quercetin mono- and di-glucosides present in fresh onions undergo complete deglycosylation during the aging process. Such profiling will provide a rapid method that can be used to assess changes in the two major quercetin glycosides during the aging process of onion bulbs.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.51-58
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• 2016

As semiconductor technology has developed, device performance has been improved. However, since device structures became smaller, circuit aging due to operational and environmental conditions can be accelerated. Circuit aging causes a performance degradation and eventually a system error. In reliable systems, a failure due to aging might cause a great disaster. Therefore, these systems need a performance degradation prediction function so that they can take action in advance before a failure occurs. This paper presents an on-line circuit performance degradation monitoring scheme for predicting a failure by detecting performance degradation during circuit normal operation. In our proposed scheme, IEEE 1149.1 output boundary scan cells and TAP controller are reused. The experimental result shows that the proposed architecture can monitor the performance degradation during normal operation without stopping the circuit.

• Animal Bioscience
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• v.36 no.5
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• pp.797-809
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• 2023

Objective: Many scientists have investigated solutions to reduce microbiological risks in dry-aged meat after the dry-aging technology was revived for high quality and value-added premium meat product in the market. This study aimed to investigate the effect of scoria powder in onggi (Korean earthenware) on the meat quality of pork loins during 21 days of dry aging and to elucidate its mechanism of action. Methods: The pork loins were randomly divided into three groups: aged in vacuum-packaging, onggi containing red clay only (OR), and onggi containing 30% red clay and 70% scoria powder (OS). Microbial analyses (total plate count and Lactobacillus spp.) and physicochemical analyses (pH, shear force, volatile basic nitrogen [VBN], water activity, 2-thiobarbituric acid reactive substances, water content, water holding capacity, cooking loss, and color analysis) of aged meat were conducted. Far-infrared ray emission, quantification of immobilized L. sakei and microstructure of onggi were investigated to understand the mechanism. Results: On day 21, the meat aged in OS exhibited lower pH, shear force, VBN, and water activity than those aged in OR, along with an increase in the number of Lactobacillus spp. OS had a smaller pore diameter than OR, implying lower gas permeability, which could promote the growth of L. sakei. Conclusion: OS improved the microbiological safety and storage stability of pork loin during dry aging by increasing number of Lactobacillus spp. possibly due to low permeability of OS.

• Journal of Animal Reproduction and Biotechnology
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• v.39 no.2
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• pp.67-80
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• 2024

Background: Post-ovulatory aging (POA) of oocytes is related to a decrease in the quality and quantity of oocytes caused by aging. Previous studies on the characteristics of POA have investigated injury to early embryonic developmental ability, but no information is available on its effects on mitochondrial fission and mitophagy-related responses. In this study, we aimed to elucidate the molecular mechanisms underlying mitochondrial fission and mitophagy in in vitro maturation (IVM) oocytes and a POA model based on RNA sequencing analysis. Methods: The POA model was obtained through an additional 24 h culture following the IVM of matured oocytes. NMN treatment was administered at a concentration of 25 μM during the oocyte culture process. We conducted MitoTracker staining and Western blot experiments to confirm changes in mitochondrial function between the IVM and POA groups. Additionally, comparative transcriptome analysis was performed to identify differentially expressed genes and associated changes in mitochondrial dynamics between porcine IVM and POA model oocytes. Results: In total, 32 common genes of apoptosis and 42 mitochondrial fission and function uniquely expressed genes were detected (≥ 1.5-fold change) in POA and porcine metaphase II oocytes, respectively. Functional analyses of mitochondrial fission, oxidative stress, mitophagy, autophagy, and cellular apoptosis were observed as the major changes in regulated biological processes for oocyte quality and maturation ability compared with the POA model. Additionally, we revealed that the activation of NAD⁺ by nicotinamide mononucleotide not only partly improved oocyte quality but also mitochondrial fission and mitophagy activation in the POA porcine model. Conclusions: In summary, our data indicate that mitochondrial fission and function play roles in controlling oxidative stress, mitophagy, and apoptosis during maturation in POA porcine oocytes. Additionally, we found that NAD⁺ biosynthesis is an important pathway that mediates the effects of DRP1-derived mitochondrial morphology, dynamic balance, and mitophagy in the POA model.