• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.547-548
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• 2011

본 논문에서는 한국전력공사에서 장기열화 시험을 수행한 154kV 고분자애자의 성능평가를 수행하고 그 결과를 1999년부터 2008년까지 한국전력공사154kV 송전선로에 시범 설치한 고분자애자의 주간코로나, 열화상 측정을 시행하고 제조회사/규격별 각 24련을 발취하여 총 168련에 대하여 한전 표준구매 규격에 따른 각종 시험을 수행하고 현 성능상태를 검증하였으며 이를 토대로 잔존 수명을 예측하고자 하였다. 대부분의 애자가 양호한 성능을 보이고 있으나 일부 애자에서는 부적합 결과를 보였으며 수명의 경우, 초기 품질계수 정보 부족 및 중간열화 상태의 데이터 부족으로 정확한 잔존수명 예측 데이터를 얻기에는 부족했으며 추가적인 가속열화시험 등의 데이터를 확보해야 할 것으로 사료된다.

• The KSFM Journal of Fluid Machinery
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• v.16 no.5
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• pp.29-35
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• 2013

Butterfly valve seated rubber has been widely used in water works and industrial fields because it has advantages which are small installation area and low weight. The size and material of butterfly valve have been selected by service environments and purposes. But there are out of the ordinary to find papers for the life characteristics of the butterfly valve. So, this study carries out the accelerated life test, which has an acceleration factor with pressure, using performance and life test equipment. Accelerated model is adopted with 3 stress level and the inverse power law model to estimate the life of the test samples. After the analysis of the test result, accelerated index has 7.0 and the acceleration factor has 208 which is applied with field condition with the pressure 6.3 bar.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.921-929
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• 2005

This paper presents an accelerated life test for burnout of tungsten filament of incandescent lamp. From failure analyses of field samples, it is shown that their root causes are local heating or hot spots in the filament caused by tungsten evaporation and wire sag. Finite element analysis is performed to evaluate the effect of vibration and impact for burnout, but any points of stress concentration or structural weakness are not found in the sample. To estimate the burnout life of lamp, an accelerated life test is planned by using quality function deployment and fractional factorial design, where voltage, vibration, and temperature are selected as accelerating variables. We assumed that Weibull lifetime distribution and a generalized linear model of life-stress relationship hold through goodness of fit test and test for common shape parameter of the distribution. Using accelerated life testing software, we estimated the common shape parameter of Weibull distribution, life-stress relationship, and accelerating factor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1735-1740
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• 2010

The propellant KM10, a single propellant manufactured nitrocellulose, is known to cause natural degradation phenomena at long term storage. The self-life was estimated using generally used high temperature acceleration aging tests to analyze the content of stabilizer and using the Arrhenius equation & Berthelot equation to calculate reaction rate constants. According to the result of this study, self-life of propellant KM10 using the Arrhenius equation & Berthelot equation appear significantly different as 43.73, 16.53years and when compared with the paper of E. R. Bixon, self-life of propellant KM10 predicted using the Arrhenius equation was reasonably determined.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1169-1176
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• 2005

In this paper, thermal reliability of a closed type BLDC (Brushless DC) motor for high speed axial fan was analyzed by the accelerated life test. The closed type BLDC (Model No. MB1-8855-J01) motor was controlled by PCB module, which was composed of various electrical components. The failure of the closed type BLDC motor happened in PCB module due to high temperature. Failure mechanism of the closed type BLDC motor appears to be electrolyte dry out of capacitor. The accelerate life test was performed in temperature stress of $85^{\circ}C\;and\;105^{\circ}C$, respectively The failure data from the accelerated life test were analyzed and the life in each stress level was estimated with 960h and 261 h. At last, both life expression according to operating temperature of PCB module and life of the closed type BLBC motor in normal condition $(50^{\circ}C)$ were suggested.

• Journal of Drive and Control
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• v.20 no.3
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• pp.9-14
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• 2023

In this paper, the selection of a reliable accelerated life test code for a 2-ton forklift was accomplished by choosing the driving resistance coefficient failure-free test time based on a 10,000-hour B₁₀ life. The overall life and average equivalent load of the vehicle were then calculated based on actual driving test conditions using the selected driving resistance coefficient. The gear train's accelerated life test code was selected by adjusting the equivalent load to a torque and rotation speed that did not exceed 125%(about 75HP) of the vehicle rated power. The safety of the test standards was validated by conducting an actual accelerated life test utilizing the proposed test method in this study and comparing the test result with the corresponding theoretical value. It is anticipated that the reliability of the accelerated life test in this paper will be enhanced, by incorporating actual driving performance data collected directly from the forklift and adjusting the conditions used in developing the accelerated life test code.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.505-511
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• 2014

The EPDM(ethylene-propylene diene monomer) rubbers used for manufacturing engine radiator hoses can be degraded by locally generated electrical stress in addition to thermal and mechanical stresses. This study presents an accelerated life prediction of the EPDM rubber under electrochemical stresses using the Arrhenius formula under various aging temperatures($60^{\circ}C$, $80^{\circ}C$, and $100^{\circ}C$). The modified life prediction formula considers the relationship between the gradient($E_a/R$) and the Arrhenius constant(C). The effects of tensile strain(5%, 10%) on the life of these rubbers were investigated. The aging temperature influences EPDM rubber life, and tensile strain was predicted. It was confirmed that the modified life prediction was within the data deviation level of the test.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.111-111
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• 2002

당사 제품인 건설 중장비용 대형 용접 구조물에 대하여, 설계단계부터 구조해석 및 초도품에 대한 Rig Test, 실차 시험 등 여러 단계를 거쳐 내구성을 평가하고 있다. 그러나 용접품 특성상 수명 평가 및 예측이 용이하지 않아 특히 내구성 개선 또는 효율 증대를 위한 경량화 등의 필요에 따른 설계 변경시 시행착오를 거치는 경우가 많다. 이에 개발 일정의 지연, 시험 비용의 증대 등이 불가피하고, 보증 수명의 증대를 통한시장 확대 등에 있어서도 애로가 있다. 또한 기존 Rig Test의 경우도 실제 사용환경과의 차이 등으로 인해 필드에서의 사용 수명을 예측하는데 한계가 있다. 이에 당 센터에서는 통계적 분석을 통한 사용 조건의 DB 구축과 제품 품질 DB의 구축 및 통합을 통하여 제관품의 특성을 반영한 용접 구조물의 가속 수명 평가법의 신뢰도 향상과 시장 목표에 부합하는 최적 설계 달성을 위한 독자적 Tool을 개발하고 있으며, 이에 대한 첫 번째 과제로 기확보 데이터에 대한 상관관계를 분석하였다.

• Fire Science and Engineering
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• v.33 no.2
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• pp.114-123
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• 2019

The paper relates to a study on the changes in performance of insulation sheath resulting from accelerated degradation of IV and HIV insulated wire. To assume insulation degradation of IV and HIV insulated wire, accelerated life tests using Arrhenius equation were conducted among accelerated life test models, and experimental samples of 0 year, 10 years, 20 years, 30 years, and 40 years in equivalent life were produced. Whereas the maximum tensile load were increased as accelerated degradation of IV and HIV insulated wire progressed, elongation percentage, rupture time, and flexibility of insulated wires were found to be gradually reduced. According to the additional surface analysis results for the insulated wires per equivalent life using a scanning electron microscope, mechanical properties of the insulator were observed to be reduced as insulation degradation resulting from aging progressed since phenomena such as formation of crystalline structures and perforation, etc. occurred on the sample surface with progression of accelerated degradation. Consequently, institutional replacement of insulated wires and preparation of repair times considering performance degradation of the insulator installed inside buildings are considered necessary in order to prevent in advance the risks of electrical fire resulting from degradation in insulation performance.

• Journal of Drive and Control
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• v.21 no.1
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• pp.16-21
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• 2024

The yaw gearbox is a key device in a wind power generator that improves power generation efficiency by rotating hundreds of tons (400 to 600 tons) of nacelle so that the blade reaches 90 degrees in the wind direction. Recently, installation sites have been advancing from land to sea as they have become super-large at (8-12) MW to increase the economic feasibility of wind power generators and utilize excellent wind resources, and the target life of large wind power generators is 25 to 30 years. The yaw gearbox of 6 to 12 sets is installed in a very complex place inside the nacelle on the tower with parallels, and it is important to secure the reliability of the yaw gearbox because if a failure occurs after installation, it costs tens to hundreds of times the price of a new product to restore. In this study, equivalent loads were calculated by analyzing failure mode and field data, accelerated life test conditions were established, and a test device was constructed to perform the accelerated life tests and performance tests to ensure the reliability of the gearbox.