• Korean Journal of Metals and Materials
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• v.49 no.3
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• pp.197-202
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• 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
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• v.45 no.1
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• pp.1-11
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• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.2
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• pp.176-182
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• 2022

Since the various characteristics of the polymer electrolyte membrane are not clearly identified, it is difficult to predict and design applications for various conditions. In this study, as a previous study on the aging of the polymer electrolyte membrane, a study was conducted on the change of mechanical properties according to the aging of the polymer electrolyte membrane. Through the tensile test of Nafion 117, the mechanical properties change due to aging was confirmed. As a result of the tensile test, it was confirmed that the aged Nafion 117 had reduced tensile strength. Through DSC measurement, aged Nafion confirmed that the glass transition temperature and enthalpy change were low, which is thought to be the effect of molecular motion and transition due to the lapse of time. The effect is thought to cause a difference in the amount of change in enthalpy, resulting in a difference in mechanical properties during tension.

• Macromolecular Research
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• v.12 no.6
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• pp.608-614
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• 2004

Isotactic polypropylene (PP) surfaces were modified with argon and oxygen plasmas using a radio­frequency (RF) glow discharge at 240 mTorr and 40 W. The changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared (IR) microspectroscopy. Under our operating conditions, the AFM image analysis revealed that longer plasma treatment resulted in significant ablation on the PP surface, regardless of the kind of plasma employed, but the topography was dependent on the nature of the gases. Specular reflectance IR spectroscopic analysis indicated that the constant removal of surface material was an important ablative aspect when using either plasma, but the nature of the ablative behavior and the resultant aging effects were clearly dependent on the choice of plasma. The use of argon plasma resulted in a negligible aging effect; in contrast, the use of oxygen plasma caused a noticeable aging effect, which was due to reactions of trapped or isolated radicals with oxygen in air, and was partly responsible for the increased surface area caused by ablation. The use of oxygen plasma is believed to be an advantageous approach to modifying polymeric materials with functionalized surfaces, e.g., for surface grafting of unsaturated monomers and incorporating oxygen-containing groups onto PP.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.1
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• pp.56-62
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• 2017

Because adhesively bonded joints are used in many structural systems, it is important to predict accurate adhesive strengths. Composite aircraft with many joints are easily exposed to low temperatures and high relative humidity. This paper presents a humidity aging effect on the adhesive strength of a composite single-lap joint (SLJ). The adhesive strength of the SLJ is predicted using a finite element analysis with a cohesive zone model (CZM) technique. The humidity aging effect is evaluated based on the adhesive strength and CZM parameters. A lap joint test is carried out on the composite SLJ specimens, which are exposed for four months of 100% R.H. at $25^{\circ}C$. The predicted strengths are in good agreement with experimental data, and the actual crack propagation is satisfactorily simulated using the local CZM technique.

• Journal of Nutrition and Health
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• v.33 no.2
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• pp.134-140
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• 2000

This study was performed to investigate the effects of n-3 fatty acids on renal function in male Sprague-Dawley rats of different ages 5-, 15- and 19-months old. The rats were fed a 20%(w/w) lipid diet containing 10% fish oil, compared with control animals fed a 20% lipid diet without fish oil for 4 weeks. The results were as follows: kidney weights were significantly higher in fish oil-fed rats compared to control rats. Plasma levels of total lipid, total cholesterol, and triglyceride markedly increased, with aging and LDL-cholesterol showing a significantly lower level in fish oil-fed rats than control rats. The urinary protein and glomerular filtration rate (GFR) increased with aging. GFR was higher in fish oil-fed rats. However, urinary protein was the same in the two groups. Renal medulla thromboxane B$_2$(TXB$_2$)tended to be lower in fish oil-fed 19-month-old rats. Urinary TXB$_2$and PGE$_2$were found to be higher proteinuria. Light microscopic examination showed interstitial inflammation, tubular atrophy, interstitial fibrosis and glomerular mesangium increase. Although glomerular sclerosis increased with aging, fish oil in the diet had no effect on histological changes. In conclusion, plasma lipid, urinary protein excretion and renal histological change showed a significant increase with aging. The reduction of TXB$_2$in the medulla and increase of GFR caused by fish oil indicated n-3 fatty acid could affect renal function in line with the hypolipidemic effect.

• Food Science of Animal Resources
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• v.25 no.2
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• pp.127-133
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• 2005

Aging effect of vacuum-packaged beef loins was investigated at $0\pm1^{\circ}C$ for 8 weeks. Hardness, chewiness, and shear force value of beef loins decreased steadily for the first 5 weeks of chilling period, but thereafter they did not changed significantly. Myofibrillar protein extractability, Mg-ATPase activity, and myofibrill fragmentation index of beef loins were increased for the first 6 weeks, and did not change for the rest period The Hunter's value in $L^{\ast},\;a^{\ast}\;and\;b^{\ast}$ of beef loin showed that no significant changes had occurred over the whole storage time. The palatability of beef loin was improved progressively for the first 5 weeks, but it became inferior thereafter. It can be concluded that the storage time to obtain optimum aging effect for the vacuum-packaged beef loin would be 5 weeks at $0^{\circ}C$ at the longest.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.3
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• pp.452-456
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• 2010

Paeony flowers to separate substances contained in the ETOH extract the polyphenol materials sympathetic to the HPLC, anti-aging and whiting used in the cosmetics extract and comparing the results follows. Extracted by a different way to keep the flowers found in the experiment, after 1 year when stored frozen material and did not show changes in appearance. Concentrated extract by HPLC, investigated the content of the type of polyphenol naringin, sinapic acid, methyl gallate, syringic acid were detected, including 11 kinds. Learn anti-aging effect in the experiment for the EtOH 80% extract showed excellent efficacy in the remaining conditions were low. The whitening effect Peony Flower extract higher than arbutin paeoniflorin was the main ingredient.

• Journal of the Korean Society of Food Culture
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• v.35 no.2
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• pp.215-223
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• 2020

Ganjang and doenjang are known as major fermented soy-based foods in Koreans. Current investigations have proved that fermented soybean foods impart anti-cancer, anti-obesity, and anti-diabetic effects. The aim of this study was to evaluate the anti-cancer activities of commercialized soy food, Ganjang, as a function of aging period. The test groups were classified into four time periods-short (under 5 years, S group), mid (under 10 years, M group), long (under 15 years, L group), and eternal (over 15 years, E group). The anti-cancer effects of Ganjang were determined by cell cytotoxicity assay of three types of cancer cell lines and splenocyte proliferation assay. Besides these assays, we also analyzed NK cell activity for cancer immunotherapy. The results show that the anti-cancer effect increased in the S and M period aging groups for all three cancer cell lines. Interestingly, similar to the anti-cancer result, splenocyte proliferation and NK activity showed the highest effect in the S and M groups. In contrast, Japanese ganjang-treated (JG1, JG2) groups and E group showed significantly reduced splenocyte proliferation. Collectively, these results suggest that the short and middle periods of traditional fermented Ganjang might have potential anti-cancer activities.

• Elastomers and Composites
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• v.22 no.2
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• pp.109-120
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• 1987

In this study, as one of the developing ways of the functional elastomer, improvement of the functionality of CB-BR was attemped through stabilization. At first the stabilization effect of CB-BR and the concentration dependancy in CB-BR were determined. Then, triazine thiol derivative(BPTT) was synthesized by reacting p-aminodiphenylamine with cyanuric chloride. Further the functional mechanism and the effects of the antioxidants were investigated using BPTT together with other various antioxidants in liquid and solid states. The results obtained are as follows: 1) The aging of CB-BR depended on the concentration and temperature. Thus, at a low temperature of $50^{\circ}C$, the aging proceeded with gel formation; at high temperature above $100^{\circ}C$ and in above 4wt% concentration, the aging occured by the formation of gel. And in concentrations below that, the aging proceeds with a decomposition caused by oxygen attacked to elastomer molecules. 2) The effect of antioxidation of CB-BR in the liquid state was at it's best when the MBIZ and BPTT were used at $110^{\circ}C$, 4hrs after the oxidation. 3) The effect of antioxidation of CB-BR in the solid state was the best choice the simultaneous use of NDBC and BPTT at $50^{\circ}C$, 30days after the oxidation.