• International Journal of Reliability and Applications
• /
• v.4 no.3
• /
• pp.131-139
• /
• 2003

There is a new trend of incorporating software coverage metrics into software modelling. This paper proposes and empirically evaluates a software reliability growth model, which relates reliability to coverage. The proposed model is derived by modifying the assumptions on which Veevers and Marshall model is based.

• Journal of Korean Society for Quality Management
• /
• v.33 no.1
• /
• pp.51-63
• /
• 2005

This paper presents the investigation on the demand of domestic companies for reliability. For persons undertaking reliability tasks of 224 companies, the questionnaire study is made to investigate the importance and necessity of reliability, needs and priorities of reliability manuals, and the appropriate scheme to propagate them by internet and telephone. By analyzing the responses according to fields of industry, types of manufacturing, numbers of employees, and total sales, we obtained the useful informations for developing and propagating reliability manuals.

• Journal of Applied Reliability
• /
• v.3 no.2
• /
• pp.103-116
• /
• 2003

We carry out reliability tests and investigate the failure mechanisms. of the wafer level vacuum packaged MEMS gyroscope sensor using an accelerated degradation test. The accelerated degradation test (ADT) is used to evaluate reliability (and/or life) of the MEMS vacuum package and to select the accelerated test conditions, which reduce the reliability testing time. Using the failure distribution model and stress-life model, we are able to estimate the average life time of the vacuum package, which is well agreed with the measured data. After improving several package reliability issues such as prevention of gas diffusion through package, we carry out another set of accelerated tests at the chosen acceleration level. The results show that reliability of the vacuum packaged gyroscope has been greatly improved and can survive without degradation of performance, which is the Q-factor in gyroscope sensor, during environmental stress reliability tests.

• International Journal of Reliability and Applications
• /
• v.5 no.2
• /
• pp.59-74
• /
• 2004

There are many uncertain parameters associated with vibration components. Their physical parameters, the machining quality of vibration components, and the applied load acting on them are all uncertain. As a result, the natural frequency and the fatigue limits are also uncertain variables. In this paper, we express these parameters of vibration components and the frequency zone of resonance through interval models; this way, the robust reliability of the vibration components is defined. The robust reliability model measures and assesses the reliability of vibration components. The robust reliability of a cantilever beam is evaluated as an example. The results show that this method is reasonable for robust reliability analysis of vibration components because it does not require a large amount of failure data, it avoids the evaluation of the probability density function, and the computation is simple.

• Journal of Applied Reliability
• /
• v.17 no.4
• /
• pp.343-354
• /
• 2017

Purpose: This paper evaluates the reliability of tapered grid couplings and presents test results through performance and life tests. Methods: The performance and life test method were presented by analyzing the failure modes for the tapered grid coupling. Zero failure test time was calculated to evaluate the reliability of tapered grid couplings and the test was performed under accelerated conditions. The nondestructive test and wear analysis using weighing were also carried out to check the failure modes of the field conditions. Conclusion: This study can be provided to improve the product reliability through failure analysis of a tapered grid coupling. The performance test results of before and after the accelerated life test were presented to confirm the improved reliability of the tapered grid coupling.

• Journal of the Korea Convergence Society
• /
• v.9 no.7
• /
• pp.223-230
• /
• 2018

In the case of a one-shot logistic equipment system that has been stored for a long time, reliability changes with the passage of time. Therefore, when the time comes to use, the storage reliability of the product is an important quality characteristic, and the existing studies have focused on the research for calculating the optimal period inspection cycle to improve the storage reliability. In this study, we analyzed the influence of the two factors on the storage reliability at the convergence point by analyzing the design reliability as well as the periodic inspection cycle. To do this, we applied the existing Martinez storage reliability model to the missile, a representative product of a one-shot system, and analyzed the quantitative effects of the design reliability and the periodic inspection cycle. From the results of the analysis, it was confirmed that the maintenance of the periodic inspection cycle is more important for the improvement of the storage reliability than the design reliability in the design reliability category of the current product.

• Journal of Applied Reliability
• /
• v.13 no.1
• /
• pp.19-30
• /
• 2013

The requirements of reliability verification for new products and technology are increasing more and more in accordance with the trend change of strength for safety technology, functional skills and emotional quality. In order to conduct the purpose of robust design from the stage of product development recently, the application of reliability technology has gradually increased such as detecting the failure mode throughout the HALT technique, accelerated tests and so on. The main results are as follows; i) through the pre-test and analysis, detected the basic performance and predictable failure mode, ii) HALT technique and process has been developed that can be applied test methods for the next new products.

• Journal of the Korean Society of Systems Engineering
• /
• v.17 no.1
• /
• pp.1-10
• /
• 2021

In this paper we proposed the alternative analysis of reliability design using redundancy technique. First, we presented the process for establishing the reliability design alternative analysis process considering the active redundancy and the standby redundancy. and then, the case analysis of A driving equipment was performed in accordance with the reliability design alternative analysis process presented. In case the series reliability design result is not met with the reliability target value. so, the target item for redundancy design of A driving equipment were selected as items with a severity of two or higher. The redundancy design applied with active and standby redundancy techniques were analyzed using BlockSim software. As a result, it was analyzed that reliability design to active redundancy with one of two elements required for A driving equipment is the most efficient compared to the target value of reliability. The results of this study can be usefully used before the reliability design is performed.

• Journal of Applied Reliability
• /
• v.14 no.4
• /
• pp.225-229
• /
• 2014

A one-shot device is defined as a product, system, weapon, or equipment that can be used only once. After use, the device is destroyed or must undergo extensive rebuild. Determining the reliability of a one-shot device poses a unique challenge to the manufacturers and users due to the destructive nature and costs of the testing. This paper presents a reliability growth prediction for a one-shot system. It is assumed that 1) test duration is discrete(i.e. trials or rounds); 2) trials are statistically independent; 3) the number of failures for a given system configuration is distributed according to a binomial distribution; and 4) the cumulative expected number of failures through any sequence of configurations is given by AMSAA model. When the system development is represented by three configurations and the number of trials and failures during configurations are given, the AMSAA model parameters and reliability at configuration 3 are estimated by using a reliability growth analysis software. Further, if the reliability growth predictions do not meet the target reliability, the sample size of an additional test is determined for achieving the target reliability.

• The Journal of Korean Physical Therapy
• /
• v.33 no.4
• /
• pp.187-192
• /
• 2021

Purpose: The purpose of the current study was to determine the intra- and inter-rater reliability of muscle thickness measurement of the TA using ultrasonography (US) conducted at different inward pressures of approximately 0.5 kg, 1.0 kg, and no pressure control. Methods: Twenty healthy subjects were recruited for this study. Two different examiners measured the thicknesses of the dominant TA of each subject randomly to assess the intra- and inter-rater reliability. The measurement values were analyzed using the intra-class correlation coefficient (ICC) with a 95% confidence interval, standard error of measurement, minimal detectable change, and coefficient of variance. Results: All intra-rater reliability ICC values showed high reliability above 0.9. Inter-rater reliability ICC values showed high reliability above 0.9 with 0.5 and 1.0 kg of inward pressure. In contrast, Inter-rater reliability ICC values showed poor reliability (0.23) with no pressure control of inward pressure. Conclusion: The findings showed that maintaining consistent inward pressure is essential for reliable results when the muscle thickness of the TA is measured by different examiners in a clinical setting.