• Journal of Applied Reliability
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• v.13 no.3
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• pp.175-190
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• 2013

This study considers reliability growth management as the excellent method for construction equipment development with the effect on decreasing COPQ(Cost of Poor Quality Cost) of new products. MIL-HDBK-189A(1981) and RADC-TR-84-20(1984) standards provide a general concept of reliability growth management including to reliability growth test, models and FRACAS(Failure Reporting and Corrective Action System). There is no study how to apply reliability growth management to construction equipment(or machine) development. This paper propose the method to apply it to construction equipment development process from the reliability target setting for developing products to launching them at market. It is expecially showing how to set target reliability for new developing equipment and the development risk to reach the reliability target in detail.

• Journal of Applied Reliability
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• v.5 no.4
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• pp.393-396
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• 2005

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.324-337
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• 2010

For the development of load and resistance factor design, reliability analysis is required to calibrate resistance factors in the framework of reliability theory. The distribution of measured-to-predicted pile resistance ratio was constructed based on only the results of load tests conducted to failure for the assessment of uncertainty regarding pile resistance and used in the conventional reliability analysis. In other words, successful pile load test (piles resisted twice their design loads without failure) results were discarded, and therefore, were not reflected in the reliability analysis. In this paper, a new systematic method based on Bayesian theory is used to update reliability index of driven steel pile piles by adding more pile load test results, even not conducted to failure, into the prior distribution of pile resistance ratio. Fifty seven static pile load tests performed to failure in Korea were compiled for the construction of prior distribution of pile resistance ratio. Reliability analyses were performed using the updated distribution of pile resistance ratio and the total load distribution using First-order Reliability Method (FORM). The challenge of this study is that the distribution updates of pile resistance ratio are possible using the load test results even not conducted to failure, and that Bayesian update are most effective when limited data are available for reliability analysis or resistance factors calibration.

• Journal of Applied Reliability
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• v.12 no.3
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• pp.201-213
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• 2012

A gear type lubrication pump is an essential component of the powertrain and has a major role for supplying oil to the gears and bearings in automatic transmission with a hydraulic clutch. Therefore, the durability test code design of lubrication pump is very important to ensure the reliability of the entire transmission and the vehicle. In this study, the design process for the life testing of lubrication pump has been generalized by four steps. The four design steps of the life testing of lubrication pump consist of the configuration of load spectrum, rain flow counting and analysis of load level, the equivalent damage assessment and test code generation. In fact, the load spectrum should be obtained from the field operating condition but that kind of data is the top secret of manufacturers. This is not open to the public in general. So we could use the artificially simulated load spectrum instead of field obtained one and focused on the development of the general process for designing the life test of a gear type lubrication pump. Reliability goals for lubrication pump, pressure, torque, temperature and load spectrum, if present, as appropriate for the given test conditions, accelerated life testing for the lubrication pump can be designed by the developed design steps.

• Integrative Medicine Research
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• v.7 no.2
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• pp.136-140
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• 2018

Background: The Sasang constitutional analysis tool (SCAT) is an integrated Sasang constitutional analysis system developed by the Korea Institute of Oriental Medicine. This study aimed to evaluate the reliability of a questionnaire for measuring personality and pathophysiological symptoms that is one of the components of the SCAT. Methods: In this study, data were collected from university students in their twenties. Tests were administered twice, with an interval of 4 weeks between tests. Test-retest data from 176 students were collected and used for analysis. Internal consistency reliability was analyzed by using Cronbach's alpha coefficient, and test-retest reliability was analyzed by using Spearman's rank correlation coefficient. Results: Cronbach's alpha coefficient was 0.788 for personality, 0.511 for eating habits, 0.718 for digestion, 0.667 for heat- or cold-wise penchant, and 0.612 for water ingestion. Spearman's rank correlation coefficients, which were used to assess correlations between test and retest results, ranged from 0.444 to 0.828. Conclusion: The internal consistency and test-retest reliability of the SCAT questionnaire were found to be satisfactory.

• Journal of Applied Reliability
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• v.18 no.3
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• pp.193-200
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• 2018

Purpose: In this study, the life of the motor is investigated by performing the accelerated life test with the brush wear of the industrial cleaner motor as the main failure mode. Methods: The accelerating stress factor of the accelerated life test is a voltage, which can increase the number of revolutions of the motor to accelerate the brush wear due to the friction between the brush and the commutator. Also, the accelerating stress level was determined after determining the maximum allowable level of the voltage through the preliminary test. Results: The motor failure time at each accelerating stress level was predicted by regression analysis with brush wear length as performance degradation data. The main failure mode, which is brush wear, of the motor was reproduced by this test. The shape parameter of the Weibull distribution was confirmed to be the same statistically at all accelerating stress levels by the likelihood ratio test. Conclusion: The life of the motor was investigated by performing the accelerated life test with the brush wear of the industrial cleaner motor as the main failure mode. Through the accelerating test method of the cleaner motor, various life expectancy and life expectancy of the acceleration factor are predicted.

• Journal of Applied Reliability
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• v.15 no.2
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• pp.84-89
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• 2015

Accelerated life tests are widely used to evaluate the product reliability within a resonable amount of time and cost. This article provides literature review about accelerated life test plans between 2006~2015. The literature on planning accelerated life tests are reviewed with respect to the test scenario, assumed accelerated model and estimation method and optimization criteria. Finally, recommendations for the future research are presented.

• International Journal of Reliability and Applications
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• v.8 no.2
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• pp.125-135
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• 2007

In this paper, testing exponentiality against new better than used in convex average and denote by (NBUCA), or its dual (NWUCA) is investigated through the U-test. The percentiles of these tests are tabulated for samples sizes n = 5(1)40. The power estimates of the test are simulated for some commonly used distributions in reliability. Pitman's asymptotic efficiency of the test is calculated and compared. Data of 40 patients suffering from blood cancer disease (Leukemia) is considered as a practical application of the proposed test in the medical sciences.

• Journal of the Korea Society of Computer and Information
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• v.20 no.10
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• pp.45-51
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• 2015

In this paper, we propose a way to reduce the SW reliability test time and human errors by utilizing the Lean Six Sigma methodology as a troubleshooting tool. Recently, SW technology is rapidly changing and the importance of SW management has been recognized. Accordingly, the SW reliable test for the SW development outcomes in one of the methods for SW quality improvement is required. However, it consumes a lot of development costs, has the time constraints and human errors in SW reliable test, so, it is difficult to meet the requirements for SW test.

• Proceedings of the Korean Reliability Society Conference
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• 2005.06a
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• pp.327-337
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• 2005

Accelerated life test models and procedure are developed to assess the reliability of Door switch. The main function of door switch is to operate bulb lamp and fan motor. The accelerated life test method and test equipments are developed using the relationship between stresses and life characteristics of the products. Using the developed accelerated life test method, the parameters of the ALT model and life time distribution are estimated and the reliability of the Door S/W at use condition if assessed. The proposed accelerated life test method and procedure may be extended and applied to testing similar kinds of products to reduce test time and costs of the tests remarkably.