• Journal of Aerospace System Engineering
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• v.10 no.1
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• pp.51-58
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• 2016

In this paper, we present some results on No-failure accelerated life test of aerial vehicle for reliability demonstration. The design of general accelerated life test consists of the three phases: 1) Estimating normal life test time of a single product from Weibull distribution model; 2) Determining the acceleration factor (AF) by utilizing the relation between the life of mechanical components and the applied torque; 3) Calculating the accelerated life test time, which comes from dividing the estimated normal life test time into AF. Then, we applied the calculated life test time to the real reliability test of the flap actuating system, while considering the requirement specification for mechanical components and operating environment of the actuation system. Real experimental processes and results are presented to validate the theory.

• Journal of Applied Reliability
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• v.14 no.2
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• pp.93-96
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• 2014

RFID (Radio Frequency IDentification) system is recognition technology which can maintain various object's information. Reliability of RFID tags is the most important factor in RFID system. In this paper, we proposed ALT (Accelerated Life Test) method for UHF RFID tags. Temperature and humidity were adopted as stress factors and the accelerated life tests were conducted in three different conditions. We performed failure analysis for identifying failure mechanism and statistical analysis of test data. In the statistical analysis, we employed Inverse Power law for relationship between tag's life and stress. Through the statistical analysis, we proposed acceleration factor for several levels of temperature-humidity. The reliability qualification test plans were also designed for the tag's target reliability.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.894-903
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• 2018

In the case of helicopters, the development of parts technology is rapidly changing, and the complexity is rapidly increasing. Particularly, the surge of various electric and electronic systems is recognized as a problem that is directly related to the safety of the helicopter. Due to these problems, there is a growing interest in reliability evaluation in the face of the problem of confirming and certifying the reliability of parts in the development stage. In this paper, the analysis of the failure mechanism of the wiper system was carried out, and the priority and importance of each failure mode were checked by using the results, and major stress factors were derived and the corresponding acceleration model was selected. Also, the accelerated lifetime test time was calculated according to the life test time, acceleration status and acceleration level of the steady state by using the selected acceleration model and characteristic values.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.695-699
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• 2010

The propellant KM10, a single propellant manufactured from nitrocellulose, was known to cause natural degradation phenomena at long term storage. In this study, the self-life was estimated using high temperature acceleration aging tests and stockpile analysis test. For the life expectancy estimation, Arrhenius equation and Berthelot equation were used in the high temperature acceleration tests, and the first order regression was used in the Stockpile analysis test. The self-life of propellant KM10 using the Arrhenius equation and Berthelot equation showed significantly different results as 43.73, 16.53 years in the high temperature acceleration test, and it showed 42.94 years in the Stockpile analysis test. The value of self-life predicted by Arrhenius equation was reasonable when compared with the result of E. R. Bixon.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.10
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• pp.1139-1143
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• 2009

Pneumatic cylinder is widely used as key component of various industry fields just like automation production line. Recently, people begin to pay attention to reduce development period and cost of pneumatic cylinder so research requirements of accelerated life test of pneumatic cylinder have been increased more than ever. In this research, we shall evaluate availability of acceleration model by statistical analysis of acceleration model's predicted value and life data which acquired in a real operation condition after finish accelerated life test of pneumatic cylinder. Also to predict the life of pneumatic cylinder in the operation condition we shall develop new acceleration model equations.

• Journal of Applied Reliability
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• v.7 no.3
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• pp.127-136
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• 2007

The accelerated life tests(ALTs) and degradation characteristics of image intensifier assembly(KIT-7) under low illuminance and high temperature were investigated. The accelerated life tests were carried out at $5{\times}10^5\;fc-40^{\circ}C,\;10{\times}10^5\;fc-40^{\circ}C,\;5{\times}10^5\;fc-50^{\circ}C,\;10{\times}10^5\;fc-50^{\circ}C$ and relationship related to illuminance and temperature was used as an accelerated life test model. An ALTA program[6] was used to calculate an acceleration factor and the test of life distribution fit, and estimate three parameters of an life test model. To sum up, MTTF 10,000 h at $5{\times}10^{-5}\;fc-40^{\circ}C$ of image intensifier assembly was certificated.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1355-1360
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• 2008

Stainless steel sheets are widely used as the structure material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. Gas welding is very important and useful technology in fabrication of an railroad car and vehicles structure. However fatigue strength of the gas welded joints is considerably lower than parent metal due to stress concentration at the weldment, fatigue strength evaluation of gas welded joints are very important to evaluate the reliability and durability of railroad cars and to establish a criterion of long life fatigue design. In this paper, ${\Delta}P-N_f$ curve were obtained by fatigue tests. Using these results, the accelerated life test (ALT) is conducted. From the experimental results, an acceleration model is derived and acceleration factors are estimated. So it is intended to obtain the useful information for the fatigue lifetime of plug and ring gas welded joints and data analysis by statistic reliability method, to save time and cost, and to develop optimum accelerated life prediction plans.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.1-8
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• 2011

Stainless steel sheets are widely used as the structure material for the railroad cars and the commercial vehicles. These kinds structures used stainless steel sheets are commonly fabricated by using the gas welding. Gas welding is very important and useful technology in fabrication of an railroad car and vehicles structure. However fatigue strength of the gas welded joints is considerably lower than parent metal due to stress concentration at the weldment, fatigue strength evaluation of gas welded joints are very important to evaluate the reliability and durability of railroad cars and to establish a criterion of long life fatigue design. In this paper, ${\Delta}-N_f$ curve were obtained by fatigue tests. Using these results, the accelerated life test (ALT) is conducted. From the experimental results, an acceleration model is derived and acceleration factors are estimated. So it is intended to obtain the useful information for the fatigue lifetime of plug and ring gas welded joints and data analysis by statistical reliability method, to save time and cost, and to develop optimum accelerated life prediction plans.

• Journal of Applied Reliability
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• v.15 no.3
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• pp.154-162
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• 2015

We have performed accelerated photo-degradation test using a 10-Sun level high irradiance $Weather-Ometer^{(R)}$ (10-Sun Ci5000) in an attempt to study acceleration and correlation between accelerated and service conditions for ink-jet ink. The accelerated test was used to predict lifetimes of ink-jet ink through the calculation of scaling factor for intensity of irradiance and duration of usage combined with estimation of lifetime distribution and inverse power model as a life-stress model. The lifetimes and acceleration factors for foreign and domestic inks were compared with each other. The results showed that the failure mechanisms and life-stress models for ink-jet ink were different among the color of ink which means that we might be in need of further study by color of inks.

• Journal of Applied Reliability
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• v.17 no.2
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• pp.103-111
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• 2017

Purpose: Accelerated degradation tests can speed time to market and reduce the test time and costs associated with long term reliability tests to verify the required service life of a product or material. This paper proposes a service life prediction method for components or materials using an accelerated degradation tests based on the relationships between temperature and the rate of failure-causing chemical reaction. Methods: The relationship between performance degradation and the rate of a failure-causing chemical reaction is assumed and least square estimation is used to estimate model parameters from the degradation model. Results: Methods of obtaining acceleration factors and predicting service life using the degradation model are presented and a numerical example is provided. Conclusion: Service life prediction of a component or material is possible at an early stage of the degradation test by using the proposed method.