• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.234-239
• /
• 2004

A study on the probabilistic methodology for the estimation of the remaining life of Pressurized pipelines containing active corrosion defects is presented. This reliability assessment is earned out using extream value distribution of the corroded defects instead of already published failure perssure moded like NG18 or ASME B31G. The failure probability of pipelines depends on the number of corroded defects. and it could be calculated directly as the area exceeded a defined L V(Limited Value of corrosion depth). The remaining life of pressurized pipelines can also be estimated by the PDF of extream value distribution as calculating the exceeded area with a defined failure probability.

• Journal of Applied Reliability
• /
• v.17 no.2
• /
• pp.112-121
• /
• 2017

Purpose: The most previous works on designing accelerated life tests (ALTs) are focused on the application of a single stress. Because of the difficulty to obtain the sufficient information in a reasonable duration using single stress only, there is needed in practice to use multiple-stress ALTs frequently. This paper presents new practical plans with two stresses for Weibull distribution. Methods: The four-level practical plans based on rectangle test region are proposed and compared with the corresponding three-level statistically optimal plans. Sensitivity analyses for assumed design parameters and life-stress relationship are conducted. Results: A procedure to choose practical ALT plans is illustrated with a numerical example and guidelines for planning two-stress ALTs are provided. Conclusion: The proposed two-stress ALT plans on practical constraints to assess a quantile of Weibull lifetime distribution at the use condition are efficient and robust.

• Industrial Engineering and Management Systems
• /
• v.11 no.4
• /
• pp.390-396
• /
• 2012

The present paper extends the idea of tightened-normal-tightened sampling scheme to group acceptance sampling plans under the time truncated life tests. We consider three famous distributions that are widely used in the area of reliability such as the generalized exponential distribution, the Weibull distribution, and the Birnbaum-Saunders distribution in the proposed sampling plan. The plan parameters are determined such that the producer's risk and the consumer's risk are satisfied at the specified median life. Extensive tables showing plan parameters are provided at various values of the experiment time and the consumer's risk for each of three distributions for the practical use. Some examples are given to illustrate the procedure of the proposed plan.

• Computers and Concrete
• /
• v.21 no.2
• /
• pp.181-187
• /
• 2018

In order to solve the life prediction problem of damaged coating steel bar in magnesium cement concrete, this study tries to establish the marginal distribution function by using the corrosion current density as a single degradation factor. Representing the degree of steel corrosion, the corrosion current density were tested in electrochemical workstation. Then based on the Copula function, the joint distribution function of the damaged coating was established. Therefore, it is indicated that the corrosion current density of the bare steel and coated steel bar can be used as the boundary element to establish the marginal distribution function. By using the Frank-Copula function of Copula Archimedean function family, the joint distribution function of the damaged coating steel bar was successfully established. Finally, the life of the damaged coating steel bar has been lost in 7320d. As a new method for the corrosion of steel bar under the multi-dimensional factors, the two-dimensional Copula function has certain practical significance by putting forward some new ideas.

• Journal of Distribution Science
• /
• v.22 no.3
• /
• pp.83-92
• /
• 2024

Purpose: With the rapid information distribution of sport-related SNS, sport industry has utilized SNS as technical solution to distribute sport and health-related information. The current study examined the effect of SNS information use for running-specific content on running engagement and psychological well-being. Research design, data and methodology: Data were collected via online survey of participants in marathon events of United States. Descriptive statistics and Chi-square test were conducted to compare demographics and psycho-behavioral outcomes among SNS information users and non-users for running-specific contents. Multivariate hierarchical regression was next employed to examine research hypotheses. Results: A mass-participant running event was used to test seven hypotheses related to the potential role of SNS for running content in promoting running engagement and life satisfaction. In general, findings revealed that use of SNS for running content along with frequency of use can perhaps facilitate running intensity and influence participation in running-related outdoor activities. Furthermore, while overall life satisfaction did not appear to be influenced by use of SNS for running content, there was a demonstrated influence on the individual satisfaction domains. Conclusions: The findings of current study suggest that sport SNS is information distribution media enhancing users' engagement and their six life satisfaction domains. Further implications were discussed.

• Proceedings of the Korean Society of Life Science Conference
• /
• 2008.10a
• /
• pp.39.2-39.2
• /
• 2008

• Journal of the Korean Data and Information Science Society
• /
• v.21 no.1
• /
• pp.71-86
• /
• 2010

In life insurance, the net premium is derived based on the expected life time distribution and expected interest rate. The losses or risks of the insurer are significantly affected by the obtained net premium. Thus, in life insurance, these two factors, the life time distribution and expected interest rate, are considered as important influential factors. In this paper, we investigate the effect of these influential factors on the net premiums, management risks, and the probability of losses. Furthermore, relative influence of these factors is also studied.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.359-359
• /
• 2017

A new soybean cyst nematode, H. sojae was reported from Korea in 2016. This species is closely related to H. glycines which has the same host plant. Morphological observations of the cyst, female, male and second-stage juveniles indicated that this species is differed from H. glycines. Especially, cysts of H. sojae appeared more round, shining and darker than that of H. glycines. The distribution of this new cyst nematode in soybean field in Korea is unknown so far. In 2016, 270 soil samples were collected from soybean fields and examined the existence of H. glycines and H. sojae. Total of 111 samples contained cysts (41.1%). Among them 77% were H. glycines and 23% were H. sojae. H. sojae is future threatening in soybean production area.

• BMB Reports
• /
• v.36 no.6
• /
• pp.558-564
• /
• 2003

In microarray data mining, one of the key problems is how to handle weak signals. Based on a bent piecewise linear accumulated distribution generally found in the microarray data, a new detectable threshold finding method is proposed to filter genes with unreliable information in this paper. More reliable and reproducible data is produced for the subsequent data mining.

• Journal of the military operations research society of Korea
• /
• v.9 no.2
• /
• pp.39-43
• /
• 1983

In this paper, we derive the likelihood function for the independent random order statistic whose underlying lifetime distribution is a two parameter Weibull form. For this purpose we first discuss the order statistic which represent a characteristic feature of most life and fatigue tests that they give rise to ordered observations. And, we describe the properties of the underlying Weibull model. The derived likelihood function is essential for establishing the statistical life test plans in the case of Weibull distribution using a likelihood ratio method.