• Journal of Korean Society of Water and Wastewater
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• v.23 no.3
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• pp.305-313
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• 2009

This paper provides a method for evaluating a residual life of water mains using a proportional hazard model(PHM). The survival time of individual pipe is defined as the elapsed time since installation until a break rate of individual pipe exceeds the Threshold Break Rate. A break rate of an individual pipe is estimated by using the General Pipe Break Model(GPBM). In order to use the GPBM effectively, improvement of the GPBM is presented in this paper by utilizing additional break data that is the cumulative number of pipe break of 0 for the time of installation and adjusting a value of weighting factor(WF). The residual lives and hazard ratios of the case study pipes of which the cumulative number of pipe breaks is more than one is estimated by using the estimated survival function. It is found that the average residual lives of the steel and cast iron pipes are about 25.1 and 21 years, respectively. The hazard rate of the cast iron pipes is found to be higher than the steel pipes until 20 years since installation. However, the hazard rate of the cast iron pipes become lower than the hazard rates of the steel pipes after 20 years since installation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.4
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• pp.366-372
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• 2009

Creep life prediction has been commonly used by a time-temperature parameter (TTP) which is correlated to an applied stress and temperature, such as Larson-Miller (LM), Orr-Sherby-Dorn (OSD), Manson-Haferd (MH) and Manson-Succop (MS) parameters. A stress-temperature linear model (STLM) based on Arrhenius, Dorn and Monkman-Grant equations was newly proposed through a mathematical procedure. For this model, the logarithm time to rupture was linearly dependent on both an applied stress and temperature. The model parameters were properly determined by using a technique of maximum likelihood estimation of a statistical method, and this model was applied to the creep data of Alloy 617. From the results, it is found that the STLM results showed better agreement than the Eno’s model and the LM parameter ones. Especially, the STLM revealed a good estimation in predicting the long-term creep life of Alloy 617.

• 대한예방의학회:학술대회논문집
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• 1994.02b
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• pp.206-233
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• 1994

The Medical Research Council has for some years encouraged collaborative clinical trials in leukaemia and other cancers, reporting the results in the medical literature. One unreported result which deserves such publication is the development of the expertise to design and analyse such trials. This report was prepared by a group of British and American statisticians, but it is intended for people without any statistical expertise. Part!, which appears in this issue, discusses the design of such trials; Part II, which will appear separately in the January 1977 issue of the Journal, gives full instructions for the statistical analysis of such trials by means of life tables and the logrank test, including a worked example, and discusses the interpretation of trial results, including brief reports of particular trials. Both parts of this report are relevant to all clinical trials which study time to death, and would be equally relevant to clinical trials which study time to other particular classes of untoward event: first stroke, perhaps, or first relapse, metastasis, disease recurrence, thrombosis, transplant rejection, or death from a particular cause. Part I, in this issue, collects together ideas that have mostly already appeared in the medical literature, but Part II, next month, is the first simple account yet published for non-statistical physicians of how to analyse efficiently data from clinical trials of survival duration. Such trials include the majority of all clinical trials of cancer therapy; in cancer trials, however, it may be preferable to use these statistical methods to study time to local recurrence of tumour, or to study time to detectable metastatic spread, in addition to studying total survival. Solid tumours can be staged at diagnosis; if this, or any other available information in some other disease is an important determinant of outcome, it can be used to make the overall logrank test for the whole heterogeneous trial population more sensitive, and more intuitively satisfactory, for it will then only be necessary to compare like with like, and not, by chance, Stage I with Stage III.

• Journal of Families and Better Life
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• v.20 no.4
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• pp.165-177
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• 2002

The purpose of this study is to analyze the effect of different working days of married working men and women on their time use on the weekend. The data collected by The National Statistical Office in 1999 was used. Among the total sample of 17,000 families, 7580 samples who are married, employed, and more than 20 yews old are selected for the analysis. This study has resulted in two major findings. (1)the working days affect on the time use on the weekend. The pattern is somewhat different by sex. The women spend more time in leisure and houseworks on the weekend as the working days decrease. However, the men do not spend more time on doing houseworks as the working days decrease. The time spent on leisure and physiologic time is increased both men and women as the change of workweek from the biweekly five-day to the weekly five-day: (2)if the five-day workweek and more flexible hours are introduced, they will contribute to Improve the quality of life of workers. This fact shows positive view at the last stage of legislation of the five-day workweek .

• Communications for Statistical Applications and Methods
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• v.14 no.3
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• pp.633-640
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• 2007

We develop noninformative priors for the ratio of the lognormal means in equal variances case. The Jeffreys' prior and reference priors are derived. We find a first order matching prior and a second order matching prior. It turns out that Jeffreys' prior and all of the reference priors are first order matching priors and in particular, one-at-a-time reference prior is a second order matching prior. One-at-a-time reference prior meets very well the target coverage probabilities. We consider the bioequivalence problem. We calculate the posterior probabilities of the hypotheses and Bayes factors under Jeffreys' prior, reference prior and matching prior using a real-life example.

• International Journal of Computer Science & Network Security
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• v.21 no.4
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• pp.131-139
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• 2021

In current time, anomaly detection is the primary concern of the administrative authorities. Suspicious activity identification is shifting from a human operator to a machine-assisted monitoring in order to assist the human operator and react to an unexpected incident quickly. These automatic surveillance systems face many challenges due to the intrinsic complex characteristics of video sequences and foreground human motion patterns. In this paper, we propose a novel approach to detect anomalous human activity using a hybrid approach of statistical model and Genetic Programming. The feature-set of local motion patterns is generated by a statistical model from the video data in an unsupervised way. This features set is inserted to an enhanced Genetic Programming based classifier to classify normal and abnormal patterns. The experiments are performed using publicly available benchmark datasets under different real-life scenarios. Results show that the proposed methodology is capable to detect and locate the anomalous activity in the real time. The accuracy of the proposed scheme exceeds those of the existing state of the art in term of anomalous activity detection.

• Journal of Korean Society for Quality Management
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• v.38 no.1
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• pp.96-100
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• 2010

The shelf-life of pharmaceutical products is the time that the average product characteristic remains within an approved specification after manufacture. Since the true shelf-life of a drug product is typically unknown, it has to be estimated based on assay results of the drug characteristic from a stability study usually conducted during the process of drug development. The nonparametric statistical methods of assessing the shelf-life of drug are considered with the current FDA regulations. Some simulation studies of nonparametric methods are also presented with the discussion.

• The Journal of Information Systems
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• v.30 no.3
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• pp.47-64
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• 2021

Purpose This study measures the degree of improvement in statistical quality experienced by data users when the data of a more convenient measurement method is extended to the analysis target to improve the quality of fine dust statistics service, and the method of expressing analysis data is revised. Ultimately, the main purpose is to explore how it can affect the quality of life of citizens. Design/methodology/approach As it was an issue the emerged as the most important issue at the time, various parties (government, private company, academia, civic groups, etc.) conducted multifaced research on fine dust, but they all focused on measuring technology and demonstrating its effectiveness there was only. This researcher redesigned the study from the viewpoint of statistical data users by changing the research subject from the technology itself to user, different from the existing research cases. The questionnaire method and structural equation were used in the study, and fine dust statistics generated through the existing method and the expanded/revised method were provided and compared for a total of 200 people. Findings Based on the results of the study, I would like to suggest what each entity should ultimately focus on to resolve the fine dust issue in the future.

• 한국데이터정보과학회:학술대회논문집
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• 2004.04a
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• pp.211-224
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• 2004

Distributing information on the internet is common in our daily life. In the past, e-mail has been the primary choice of exchanging information, but instant messengers are gaining popularity abroad and domestically because of their immediate responses. Instant messaging has become the fastest growing communication technology in recent years. Instant messaging is effectively a chat room for two people. Users that have accounts with the same provider are able to send messages via computer in real time. Instant messaging has exploded into the business world as companies now utilize the technology for everything from interoffice communication to client/customer communication. In this paper, we propose a method of instant messenger system design for effective collaboration of statistical data collection.

• Journal of Families and Better Life
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• v.21 no.1
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• pp.61-72
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• 2003

This study examines the problematic fact that most housewives are excluded from receiving the benefits of the National Pension Plan in South Korea. The National Pension Plan assigns no value to housework or household production, which in turn discourages full-time housewives from participating voluntarily in the Plan. In this article, I propose to utilize Credit Splitting and Pension Sharing in order to take into account full-time housewives' economic contribution in the National Pension Plan. In this article, I also discuss the ranges and application methods of the Credit Splitting and Pension Sharing. For this study, I have analyzed the data of 11,967 unemployed married women living with spouses published in“Research Data on Everyday Life Time Usage”by the Korea National Statistical Office in 1999. The value of the full-time housewives' labor varies depending on the methods of estimation. However, all estimated values exceed the average value assigned to the housewives by the National Pension Corporation. It is clear that full-time housewives' unpaid labor contributes a great deal to the formation of household property and wealth, which is a valid reason for Pension Sharing and Credit Splitting. This article also provides logical factors to consider in the process of Pension Sharing and Credit Splitting, which can be used for developing computerized software to determine a full-time housewives' labor value at the time of divorce or for any other purpose.