• Journal of Applied Reliability
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• v.11 no.4
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• pp.343-356
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• 2011

This paper proposes an accelerated life evaluation of drive shaft. The life test of drive shaft for independent suspension type AWD vehicle should be performed by use of the least test sample because many number of samples can't be used for the test because of its mass capacity and high price. We calculated the no failure test time by application of no failure test concept, and the already performed test data for drive shaft are applied for some kinds of reliability coefficients which are needed for calculation of life test time. And, for analysis of real driving condition of vehicle, the load spectrum is prepared using the needed road condition and vehicle data. The inverse power model is used for accelerated life test. The equivalent torque of load spectrum is achieved by use of Miner's Rule, and then the final accelerating condition is determined by decision of the accelerated test torque. This paper shows that the accelerated life test results corresponds with the target life and the proposed life test method can be very well applied to no failure life test for mass capacity machinery components.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1221-1229
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• 2014

This paper proposes an approach for predicting the fatigue life of a propeller shaft of a forklift truck by an accelerated life test method. The accelerated life test method adopted in this study is the calibrated accelerated life test, which is highly effective in the prediction of the lifetime and enables significant reduction of the test time as well as a quantification of reliability in the case of small sample sizes. First, the fatigue test was performed under two high stress levels, and then, it was performed by setting low stress levels in consideration of the available test time and extrapolation. Major reliability parameters such as the lifetime, accelerated power index, and shape parameter were obtained experimentally, and the experimentally predicted lifetime of the propeller shaft was verified through comparison with results of an analysis of load spectrum data under actual operating conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.12
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• pp.1305-1311
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• 2015

A butterfly valve is a type of flow-control device typically used to regulate a fluid flow. This paper presents an estimation of the shape parameter of the Weibull distribution, characteristic life, and $B_{10}$ life for a concentric butterfly valve based on a statistical analysis of the reliability test data taken before and after the valve improvement. The difference in the shape and scale parameters between the existing and improved valves is reviewed using a statistical hypothesis test. The test results indicate that the shape parameter of the improved valve is similar to that of the existing valve, and that the scale parameter of the improved valve is found to have increased. These analysis results are particularly useful for a reliability qualification test and the determination of the service life cycles.

• Tribology and Lubricants
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• v.31 no.2
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• pp.35-41
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• 2015

A water-pump located in the cooling area of a car circulates cooling water. A particular bearing element, known as a water-pump bearing, installed in the rotating part carries the entire load. The failure of this water-pump bearing has a direct impact on the failure of the automobile engine, and so securing its reliability is crucial. Several researchers have examined the design principles of the water-pump bearing, but there are no reports on the life characteristic of the bearing yet. Herein, we report the construction of test equipment to reproduce the spalling of the roller contact, which is the main failure mode of the chosen water-pump bearing. We chose the radial load as an accelerated stress factor and validated the failure mode by monitoring the surface defects. We conducted the accelerated life test after determining the accelerated stress level through a combination of finite element analysis and a preliminary test. In the life tests, we used an accelerometer to perform failure diagnosis. In the last stage of this study, we present a statistical reliability analysis. Thus, we fully estimated the shape parameter of the water-pump bearing, accelerating level on the load , and the lifetime (MTTF and B₁₀ life) under real use conditions, and finally proposed an interval estimation value considering the uncertainty of the estimated value.

• New & Renewable Energy
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• v.16 no.4
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• pp.49-64
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• 2020

Photovoltaic and Thermal collector (PV/T) systems are renewable energy devices that can produce electricity and heat energy simultaneously using solar panels and heat exchangers. Since PV/T systems are exposed to the outdoors, their reliability is affected by various environmental factors. This paper presents a reliability test for a PV/T system and evaluates the test results. The reliability assessment entails performance, environment, safety, and life tests. The factor that had the greatest influence on the life of the system was the hydraulic pressure applied to the heat exchanger. A test was conducted by repeatedly applying pressure to the PV/T system, and a reliability analysis was conducted based on the test results. As a result, the shape parameter (β) value of 5.6658 and the B10life 308,577 cycles at the lower 95% confidence interval were obtained.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.2
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• pp.208-213
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• 2008

In order to assess the reliability of the electronics control unit for vehicles, accelerated life test model and procedure are developed. By using this method, failure mechanism and life distribution are analyzed. The main results are as follows : i) the main failure mechanism is degradation failure that is, junction destruction of a semiconductor resin by high temperature. ii) the life distribution of the electronics control unit for vehicles is fitted well to Weibull life distribution and the accelerated life model of that is fitted well to Arrhenius model. iii) at the result of the life distribution, accelerated life test method is developed, and test time for life assessment will be shortened by 5,000 hours by this test method.

• Journal of Applied Reliability
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• v.9 no.3
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• pp.195-218
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• 2009

Wiper motors are used in every automobile. They are exposed to a very diverse environment and consists of several components and, therefore needs careful approach to the enhancement and assessment of reliability of the item. In this article reliability standards for wiper motors are established in terms of quality certification test and failure rate test.

• Journal of Korean society of Dental Hygiene
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• v.17 no.4
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• pp.555-564
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• 2017

Objectives: The purpose of the study is to investigate the oral health assessment and satisfaction according to recognition and beneficiary oral health projects for oral health promotion of the elderly. Methods: The subjects were elderly over 65 years old in Jeonbuk province. The study instrument was structured questionnaire including general characteristics, oral care condition, recognition of project, satisfaction of project, geriatric oral health assessment index, life satisfaction. For data analysis, the study used independent t-test, one way ANOVA and Pearson correlation analysis. Results: The subjects of this study were well aware of the perceived health status of oral health projects. Satisfaction scaling project was the highest in the satisfaction of the received projects. People who recognized the oral health project had a high oral health assessment index. People who benefit from oral health project showed higher satisfaction in life. Conclusions: As for the elderly's perception on oral health care, they showed higher oral health assessment index and life satisfaction.

• Tribology and Lubricants
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• v.27 no.3
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• pp.134-139
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• 2011

The mechanical equipments which are exposed to impure environment undergo significant reductions in their own lifetimes. Several environmental test procedures have been developed to analyze these phenomena. Moreover in the industry to require shorter development duration, accelerated life testers artificially add test containments into machines. In this research JIS Z 8901 test powder was added into internal gear pumps which are used as oil pumps in vehicles and thus the effects of the addition on the degradation of the pumps were examined. Three kinds of contaminants were selected. Two of the contaminants are identical in particle size but different in the composition of the ingredients. The other pair have identical ingredients and composition but different particle size. The quantity of contaminants was also an interesting factor in this study. The results show that each JIS contaminant caused notable degradation in the discharge flow characteristic of pumps while friction torque degradation did not have any tendency. Finally leakage rates were deduced and equivalent wear volume ratios were calculated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1105-1110
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• 2009

Vocational rehabilitation is defined as a process which helps people with disabilities to maintain life of non-disabled people and vocational assessment is a part of it. Traditionally, vocational assessment is performed through using of assessment tools, vocational counseling and so on. It is very efficient to apply vocational assessment to people with disabilities using the internet, but we should provide them with web accessibility. In this paper, we design and implement the aptitude test system for people with visual impairment supporting web accessibility. We develop the aptitude test system using the Holland Test which is the assessment tool of career guidance and counseling. We also show that the aptitude test system for people with visual impairment supports web accessibility more than previous Holland Test which is served in the internet.