• Journal of the Korean Society of Child Welfare
• /
• no.26
• /
• pp.61-86
• /
• 2008

This Study examines the relationship between Cumulative Risk and Behavioral Problem of children's in divorced family. The cumulative risk was Summed for each children to creative an cumulative scores. Scores on the index ranged from 0 to 12. Cumulative Risk was associated with Behavioral Problem. Moreover the analyses revealed positive, linear associated between Cumulative Risk and Behavioral Problem. Cumulative Risk predicted Problem Behavioral of Divorced Family's Children. Finding indicate that the amount of risk in Divorced Family's childrens lives was useful for determining the extent to which cumulative risk exposure plays an etiological role in Behavioral Problem. On the basis of these results, this article provided some suggestions for promoting of children welfare.

• Korean Journal of Child Studies
• /
• v.35 no.2
• /
• pp.43-61
• /
• 2014

The main purpose of this study was to investigate the paths from the cumulative risk factors to infant's development at 24 months of age via the mediation of maternal parenting behaviors. The data consisted of 3 year's worth of data harvested from 1802 families participating in the Panel Study on Korean Children (PSKC). The results revealed that cumulative family risk factors tended to stay in the family in relatively stable ways. Early risk factors significantly predicted later risk factors. Cumulative risk factors were negatively associated with the parenting styles of mothers, which in turn, significantly predicted the development of the infants concerned. Statistical tests supported the notion that mothers' parenting behavior is the mediator of the relation between family risk factors and infant's developmental outcomes.

• Journal of the Korean Society of Child Welfare
• /
• no.54
• /
• pp.79-111
• /
• 2016

The purpose of this study was to examine the structural models in which early cumulative risk factors affect children's language(indicated by expressive vocabularies) and social development(indicated by peer competence) at age 3 thorough their effects on the home learning environment. To examine the hypothesized models, the data of 1,725 families from the second and the fourth waves of the Panel Study of Korean Children was used. Correlation analysis and structural equation modeling were conducted to test the models. First, the cumulative risk factors at age 1 and 3 were highly correlated, implying the stability of the risk factors over time. The more cumulative risk factors at age 1 predicted the lower level of the home learning environment at age 3, which, in turn, was significantly related to both language and social development at age 3. However, the early cumulative risk factors did not directly influence later developmental outcomes. Moreover, the cumulative risk factors at age 3 were directly related to the child's language development, but neither social development northe home learning environment. In addition, the mediational role of the home learning environment (i.e., cumulative risk factors at age 1${\rightarrow}$home learning environment${\rightarrow}$language and social development) was statistically supported. In conclusion, the early cumulative risk factors in infancy indirectly predicted children's development at age 3 through the home learning environment. The practical implications for the early intervention and support for the families with infants who are experiencing multiple risk factors were discussed.

• Journal of Applied Reliability
• /
• v.16 no.1
• /
• pp.56-63
• /
• 2016

Purpose: The purpose of this study is to point out that the Kaplan-Meier method is not valid to calculate the survival probability or failure probability (risk) in the presence of competing risks and to introduce more valid method of cumulative incidence function. Methods: Survival analysis methods have been widely used in biostatistics division. However the same methods have not been utilized in reliability division. Especially competing risks cases, where several causes of failure occur and the occurrence of one event precludes the occurrence of the other events, are scattered in reliability field. But they are not noticed in the realm of reliability expertism or they are analysed in the wrong way. Specifically Kaplan-Meier method which assumes that the censoring times and failure times are independent is used to calculate the probability of failure in the presence of competing risks, thereby overestimating the real probability of failure. Hence, cumulative incidence function is introduced and sample competing risks data are analysed using cumulative incidence function and some graphs. Finally comparison of cumulative incidence functions and regression type analysis are mentioned briefly. Results: Cumulative incidence function is used to calculate the survival probability or failure probability (risk) in the presence of competing risks and some useful graphs depicting the failure trend over the lifetime are introduced. Conclusion: This paper shows that Kaplan-Meier method is not appropriate for the evaluation of survival or failure over the course of lifetime. In stead, cumulative incidence function is shown to be useful. Some graphs using the cumulative incidence functions are also shown to be informative.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.23 no.1
• /
• pp.20-26
• /
• 2013

Objectives: This study was conducted to evaluate the health risk of workers exposed to butyl glycidyl ether to prevent them from developing occupational diseases. Methods: The workplaces that coat floor with epoxy were selected and the samples were collected and analyzed with NIOSH 1616 Method. We calculate workplace reference concentration using with NOAEL estimated by the study of Anderson et al. in 1978. Risk was calculated by the ratio of exposure to workplace reference concentration. Monte-Carlo simulation was performed to derivate the median, cumulative 90%, and cumulative 95% value by using Crystal Ball. Results: Butyl glycidyl ether is a skin, eye irritator and can result in central nervous system depression, allergic reaction. NOAEL was 38 ppm and workplace reference concentration was calculated as 0.73 ppm corrected with uncertainty factors. Geometric mean was 1.152 ppm and geometric standard deviation was 1.522 by the workplace environment measurement. The median, cumulative 90%, and cumulative 95% value of risk were calculated as 1.617, 1.934, and 2.092, respectively. Conclusions: Not only cumulative 90% and cumulative 95% value but also the median of risk is higher than 1.0 by the risk characterization, so it can do a lot of harm to workers. Therefore, the process of derivating workplace reference concentration and the appropriacy of the uncertainty factors should be re-examined.

• Journal of the Korean Society of Safety
• /
• v.12 no.4
• /
• pp.153-160
• /
• 1997

The purpose of this paper is to present design recommendations intended to reduce the risk of cumulative trauma disorders(CTD) at the Osram Slvania, Inc. The CTD risk index score is a method which quantifies the risk factors to CTD incidence, namely extreme postures, high force elements, frequent damaging hand motions, and other miscellaneous factors. The risk index score quantified the jobs as a single composite value by weighting the scores for each risk factor. Jobs were prioritized for capital outlays in workstation redesign, and the factors of highest risk within each job could be identified. Three jobs which presented the greatest risk of CTD incidence were redesigned ergonomically.

• Nuclear Engineering and Technology
• /
• v.56 no.3
• /
• pp.819-823
• /
• 2024

The main criteria used in NEI 18-04 to define SSCs as risk-significant include (1) the SSC is required to keep all LBEs within the F-C target, and (2) the total frequency with the SSC failed exceeds 1% of the limit for at least one of the three cumulative risk metrics used for evaluating the integrated plant risk. The first one is a reasonable criterion in determining the risk significant SSCs. However, the second criterion may not be adequate to serve the purpose of determining the risk significance of SSCs. In the second criterion, the cumulative risk metric values representing the integrated plant risk (less the preventive and mitigative effects of the SSC being evaluated) are compared to a risk limit that represents a very small contribution to the overall integrated plant risk, which corresponds appropriately to the contributions from individual SSCs. The easiest approach to redefine the NEI 18-04 definition of risk-significant SSCs in relation to the integrated plant risk metrics is to compare the difference, between the risk metric value calculated with the SSC failed and the risk metric value calculated with the SSC credited, with 1% of the risk limit established for the integrated plant risk metrics.

• Communications for Statistical Applications and Methods
• /
• v.23 no.6
• /
• pp.555-562
• /
• 2016

Interval censored data often occur in an observational study where the subject is followed periodically. Instead of observing an exact failure time, two inspection times that include it are available. There are several methods to analyze interval censored failure time data (Sun, 2006). However, in the presence of competing risks, few methods have been suggested to estimate covariate effect on interval censored competing risk data. A sub-distribution hazard model is a commonly used regression model because it has one-to-one correspondence with a cumulative incidence function. Alternatively, Klein and Andersen (2005) proposed a pseudo-value approach that directly uses the cumulative incidence function. In this paper, we consider an extension of the pseudo-value approach into the interval censored data to estimate regression coefficients. The pseudo-values generated from the estimated cumulative incidence function then become response variables in a generalized estimating equation. Simulation studies show that the suggested method performs well in several situations and an HIV-AIDS cohort study is analyzed as a real data example.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.11 no.1
• /
• pp.85-91
• /
• 2001

Background : It goes without saying that cumulative trauma disorders is spreading to various types of occupation in many advanced countries including America, and it forms considerable rate of total occupational disorders already. and as the result of it, the seriousness of worker health problem and economic loss owing to production loss, recuperation expense, etc. are on the increasing trend through whole society. In case of Korea, the related measures as well as accurate fact-finding survey data on cumulative trauma disorders aren't prepared in detail, so it implies forward problem would be serious. Purpose : The purpose of this study is to draw the risk factor of cumulative trauma disorders in production factory, to forecast the rate of occurrence of cumulative trauma disorders on the basis of subjective symptoms, and to present forward realistic and effective prevention measures by showing the risk of cumulative trauma disorders, objecting the production factory of a domestic riding automobile assembly shop, by estimating in the aspect of human-engineering through the analysis of risk factor being a cause of cumulative trauma disorders. Methods : For this study, I investigated work type and on-duty hours, breathing time, and subjective symptoms of cumulative trauma disorders through questionnaire, objecting the workers in press. car body, coating, and outfit factory. Results : As a result of research, 81.2% of workers were in the physical burden due to present working, and the highest prevalence by part of body is an waist. The higher a rule score, The higher the number of workers complaind for working intensity, and the higher age work duration, tool used time, the higher prevalence of subjective symptoms by part of body. The number of workers complaind subjective symptom for treatment is the highest in drugstore.

• Journal of Korean Society for Quality Management
• /
• v.39 no.2
• /
• pp.320-328
• /
• 2011

This research proposes comprehensive models for analyzing common cause failures (CCF) due to cumulative shocks and to assess system reliability under the CCF. The proposed cumulative shock models are based on the binomial failure rate (BFR) model. Six kinds of models are proposed so as to explain diverse cumulative shock phenomena. The models are composed of the initial failure probability, shape parameter, and the total shock number. Some parameters of the proposed models can not be explicitly estimated, so we adopt the Expectation-maximization (EM) algorithm in order to obtain the maximum likelihood estimator (MLE) for the parameters. By estimating the parameters for the cumulative shock models, the system reliability with CCF can be assessed sequentially according to the number of cumulative shocks. The result can be utilizes in dynamic probabilistic safety assessment (PSA), aging studies, or risk management for nuclear power plants. Replacement or maintenance policies can also be developed based on the proposed model.