• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.691-696
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• 2007

In this study accelerated aging test equipment was developed to simulate domestic weather condition for accelerated aging test of polymer housed distribution surge arresters. Polymer arresters were aged for 3,000 hours by this test equipment and chemical and electrical characteristics analysis of surge arresters were conducted after aging test. In addition, performance assessment of outdoor installed arresters for 3 years was conducted to compare aging effect between accelerated aging test and natural aging. Through this experiment it is verified that the capability of the proposed aging test for simulating natural aging and the housing material and disconnector of domestic polymer arresters can be deteriorated by the long time field operation.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.6
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• pp.577-585
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• 2008

STATEMENT OF PROBLEM: The discoloration of anterior teeth restoration is one of the material problems demanding retreatment. OBJECTIVES: To evaluate the color stability and affecting factors on esthetic restorative materials when subjected to accelerated aging. MATERIAL AND METHODS: This study was conducted using porcelain disks (IPS Empress 2-glazed, IPS Empress 2-polished), direct restorative resin disks (SYNERGY Duo) and indirect restorative resin disks (Sinfony, TESCERA ATL). Accelerated aging was done by precipitating the specimens in 38.C distilled water and irradiating with xenon light, and the total irradiation was 397.98 KJ/mm. Color and microhardness change of the specimens were measured before accelerated aging and after 100 hours, 200 hours and 300 hours of accelerated aging, and Surface of the specimens were examined with SEM before and after 300 hours of accelerated aging. RESULTS: 1. After 300 hours' accelerated aging, a ${\Delta}E$ value was 3.3 or lower in IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony. 2. After 300 hours' accelerated aging, gloss was lost and surface changes including microcracks were observed in TESCERA ATL and SYNERGY Duo, and color changes of them ranged between 3.58 and 6.40 ${\Delta}E$ units. 3. During 300 hours' accelerated aging, the microhardness of surface was increased by 3.21 - 19.64% in all kinds of composites resin. CONCLUSION: After 300 hours' accelerated aging, SEM images IPS Empress 2-glazed, IPS Empress 2-polished and Sinfony showed little morphological change and their color changes were considered to be clinically acceptable. And there was significant correlation between microhardness changes and color changes of composites (P < .05).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.10-14
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• 2001

In order to assess the long-tenn reliability of polymer insulators for distribution power systems, we have developed the accelerated aging test method which can simulate the operation conditions. In this study, 3000 hours aging test for 4 kinds of polymer insulators has been completed by the developed accelerated aging test. After 3000 hours aging test, visual inspection and electrical tests were carried for identifying a change of characteristics. Some specimens showed the surface erosion and the manufacturing defect. In the electrical tests, the wet flashover voltage was significant1y decreased by the accelerated aging test. In comparison with the field-aged polymer insulators, it can be concluded that the developed test method can evaluate the long-tenn reliability within short time and screen the manufacturing defect.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.88-95
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• 2015

The accelerated thermal aging of CSPE(Chloro Sulfonate Polyethylene) was carried out for 40.41, 121.22, 202.04 days, 16.82, 50.45, 84.09 days and 7.32, 21.96, 36.59 days at 100, 110, and $120^{\circ}C$, respectively, which are equivalent to 20, 60, 100 years of aging at $50^{\circ}C$. The permittivities and the apparent densities of the accelerated thermally aged CSPE samples are increased with accelerated thermal aging year but EAB(Elongation at Break) is decreased with that. The dielectric strength and the electric breakdown of the non-accelerated and accelerated thermally aged CSPE samples do not depend on accelerated thermal aging year and applied voltage rising time. density and EAB measures.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1391-1393
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• 2008

In this paper, the long-term reliability for 1.25G transceiver in use of high speed optical access network is investigated. High temperature storage tests and accelerated life tests are used to long-term reliability. Accelerated aging test have been during 3,000 hour of the three accelerated aging conditions by caused high temperature stress. Mean life is assumed to follow the Arrhenius relationship and analysis from the failure data obtained in the accelerated aging conditions.

• The Journal of Advanced Prosthodontics
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• v.14 no.6
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• pp.360-368
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• 2022

PURPOSE. This study assessed the physical and mechanical properties of interim crown materials fabricated using various digital techniques after accelerated aging. MATERIALS AND METHODS. Three groups of interim dental restorative materials (N = 20) were tested. The first group (CO) was fabricated using a conventional manual method. The second group (ML) was prepared from prefabricated resin blocks for the milling method and cut into specimen sizes using a cutting disc. The third group (3D) was additively manufactured using a digital light-processing (DLP) 3D printer. Aging acceleration treatments using toothbrushing and thermocycling simulators were applied to half of the specimens corresponding to three years of usage in the oral environment (N = 10). Surface roughness (Ra), Vickers microhardness, 3-point bending, sorption, and solubility tests were performed. A 2-way analysis of variance (ANOVA) and Fisher's multiple comparison test were used to compare the results among the groups. RESULTS. The mean surface roughness (Ra) of the resin after accelerated aging was significantly higher in the CO and ML groups than that before aging, but not in the 3D group. All groups showed reduced hardness after accelerated aging. The flexural strength values were highest in the 3D group, followed by the ML and CO groups after accelerated aging. Accelerated aging significantly reduced water sorption in the ML group. CONCLUSION. According to the tested material and 3D printer type, both 3D-printed and milled interim restoration resins showed higher flexural strength and modulus, and lower surface roughness than those prepared by the conventional method after accelerated aging.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1447-1448
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• 2011

The CSPE cables are used for three years in nuclear power plant. The accelerated thermal aging of chloro sulfonate polyethylene(CSPE) jacket of test cables were carried out for the period equal to 10, 20 and 30 years in air at 90 and $100^{\circ}C$, respectively. The electrical volume resistivity, density, XPS, FE-SEM, EDS and XRF of the accelerated thermal aging of CSPE were measured. The validation of condition monitering method of accelerated thermal aging CSPE was estimated by them. The best validation of condition monitoring method of accelerated aging CSPE is electrical volume resistivity because change thermal of the specimen showed distinction.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.4
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• pp.238-243
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• 2015

The vegetable insulating oils are substitute for the mineral oil in power transformer. Vegetable insulating oils has higher flash/fire point and biodegradability than conventional mineral oils. In this paper, we investigated the dissolved gas analysis of vegetable oils. In the experiment, I had to accelerated aging under the same conditions mineral oil and vegetable oils. Accelerated aging proceeded to about 100% of the life of oil-filled transformer. In addition, we performed gas analysis of insulating oil of accelerated aging progress. The experiment results of the five gases was measured with the exception of Hydrogen and Acetylene. The mineral oil and vegetable oils gas is generated in a similar tendency depending on the accelerated aging. As a result, vegetable oils, can be dissolved gas analysis by method such as mineral oil.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1148-1152
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• 2012

The vegetable-based insulating oils are substitutes for mineral oils in oil-filled transformer. The important properties of vegetable insulating oil is their higher flash/fire point and biodegradability than conventional mineral oils. The large oil-filled transformer eliminate the risk of explosion and fire should the transformer fail and oil ignite owing to high flash/fire point of vegetable insulating oil. In addition, higher biodegradability of vegetable insulating oils can let the oil spill damage reduced. In this experiment, the real oil-filled transformers using mineral oil and vegetable oil have accelerated aging. After working on the 100% accelerated aging experiment were conducted comparing the transformer. The hottest-spot temperature using thermal coefficients were calculated to determin the degree of accelerated aging. As a result, apply mineral oil transformer in accordance with the accelerated aging life come to an end. In contrast, vegetable insulating oils showed the opposite characteristics. Vegetable insulating oil compared to the mineral oil are found to be an long life. As a result, the vegetable oil has a long-term stability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1832-1838
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• 2010

Aging of transformer insulating material in natural ester insulating oil is compared to that in conventional transformer oil. Aging of insulating paper and insulating oil have been studied by performing accelerated thermal aging test. Sealed aging test vessels containing cooper, laminated core, Kraft paper and insulating oil(natural oil or mineral oil) were aged at $140^{\circ}C$ for 500, 1000, 1500 and 2000 hours. Insulating oils after aging are investigated with total acid number, breakdown voltage and viscosity. Also, degradation of insulating paper after aging is determined using breakdown voltage and mechanical strength. Accelerated aging studies demonstrate a slower aging rate for natural ester insulating oil compared to the rate for conventional mineral oil.