• Title/Summary/Keyword: associated random variable

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Threshold Crossing Rate, Phase Distribution and Group Properties of Nonlinear Random Waves of finite Bandwidth (유한한 Bandwidth를 갖는 비선형 불규칙 파열에서의 Threshold Crossing Rate, 위상분포와 파군특성)

  • Jo, Yong-Jun
    • Journal of Korea Water Resources Association
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    • v.30 no.3
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    • pp.225-233
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    • 1997
  • The nonlinear effects on the statistical properties of wave groups in terms of the average nomber of waves in a group and the mean number of waves in a high run is studied in this paper utilizing the complex envelope and total phase function, random variable transformation technique and perturbation method. It tures out that the phase distribution is modified significantly by nonlinearities and it show systematic excess of values near the mean phase and the corresponding symmetrical deficiency on both sides away from the mean. for the case of threshold crossing rate, it turns out that threshold crossing rate reaches its maxima just below the mean water level rather than zero and considerable amount of probability mass is shifted toward the larger values of water surface elevation as nonlinearity is getting profound. Furthermore, the mean waves in a high run associated with nonlinear wave are shown to have larger values than the linear counterpart. Similar trend can also be found in the average number of waves in a group.

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A Method for Schedule Simulation Considering Rework and Uncertainty (재작업과 불확실성을 고려한 일정 시뮬레이션 방법론)

  • Kim, Chan-Mook;Park, Young-Won
    • Journal of the Korean Society for Railway
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    • v.12 no.1
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    • pp.135-143
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    • 2009
  • The majority of development projects fail to meet their target schedule and cost, with the overrun typically between 40 and 200 percent. These overruns happen because the planners underestimate the work or do not consider the need to rework at project planning. Representative schedule planning/management techniques such as Gantt Chart, PERT/CPM etc. that are used in domestic project planning are unable to reflect rework. This paper proposes a method to consider rework to provide more realistic estimates at schedule planning. Additionally, to prevent the underestimation of the work this paper proposes a simulation method that calculates a probabilistic estimated schedule and the associated variance based on the random variable modeling of individual task completion dates.

Changes in Co-Occurrence of Smoking and Harmful Drinking among Youth: a Study from the Chi Linh Demographic - Epidemiological Surveillance System in Vietnam, 2006-2013

  • Duong, Minh Duc;Le, Thi Vui;Nguyen, Thuy Quynh;Hoang, Van Minh
    • Asian Pacific Journal of Cancer Prevention
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    • v.17 no.sup1
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    • pp.55-63
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    • 2016
  • Smoking and harmful drinking dramatically increase health risks but little is known about their cooccurrence and factors that influence this co-habit, limiting development and implementation of appropriately targeted prevention interventions. This study was conducted among youth aged 10-24 years old in the Chi Linh Demographic - Epidemiological Surveillance System (CHILILAB DESS). The total numbers in the first, second and third rounds in 2006, 2009 and 2013 were 12,406, 10,211, and 7,654, respectively. A random-effects logit model controlling for both time-variant and time-invariant variables was applied to explore factors associated with current smoking, harmful drinking, and occurrence of smoking and harmful drinking together. We found dramatically increasing trends in current smoking, harmful drinking and co-occurrence among youth. Our results indicate similar health problems among youth in peri-urban areas in Vietnam. Demographic characteristics (older age, being male, being unmarried, and having informal work) appeared to be predictors for smoking and drinking behaviour. Besides, peer and family members had significant influence on smoking, whereas having a close-friend who was smoking was the most important variable. The results suggested that smoking and harmful drinking should not be solved with separate, stand-alone interventions but rather with integrated efforts.

A Study on the relationship between work from home and sleep disturbances among workers: using the 5th working environment survey (제5차 근로환경조사를 통해 조사된 재택근무와 수면장애 간의 연관성 연구)

  • Hyun-Jung Kim;Seo-Yeon Park;Hyung Jin Kwon;Yi-Qin Fang;Lei Lee
    • Journal of Korean Academy of Dental Administration
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    • v.11 no.1
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    • pp.78-88
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    • 2023
  • This study aimed to analyze the correlation between working from home and sleep disorders among domestic workers using data from the 5th Working Environment Survey in 2017. Out of the total 30,108 wage workers, 818 employees work from home and 4,090 work in an office. A random sample of 1:5 pairs, considering gender and occupational group, was selected from these employees as the study subjects. The analysis included personal characteristics, occupational characteristics, work-from-home arrangements, and sleep disorders. Age, education, employment status, years in the workforce, weekly working hours, work-life balance, self-perceived health, depression, and anxiety were all adjusted as potential confounding variables. Conditional logistic regression analysis was conducted to examine the relationship between working from home (independent variable) and sleep disorder (dependent variable). This analysis aimed to analyze the correlation between working from home and sleep disorder. The analysis revealed that working from home was associated with sleep onset latency disorder OR=3.23 (95% CI=2.67~3.91), sleep maintenance disorder OR=3.67 (95% CI=3.02~4.45), and non-restorative sleep OR=3.01 (95% CI=2.46~3.67), which showed a statistically significant relationship with all three types of sleep disorders. Factors influencing the correlation between working from home and sleep disorders included work-life balance, social isolation, and anxiety.

Prevalence and risk factors of helminth infections in cattle of Bangladesh

  • Rahman, A.K.M.A.;Begum, N.;Nooruddin, M.;Rahman, Md. Siddiqur;Hossain, M.A.;Song, Hee-Jong
    • Korean Journal of Veterinary Service
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    • v.32 no.3
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    • pp.265-273
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    • 2009
  • A cross-sectional survey was undertaken to identify risk factors and clinical signs associated with parasitic helminth infections of cattle in Mymensignh district of Bangladesh. A nonrandom convenience sampling method was used to select 138 animals from 40 farmers/herds. The eggs per gram of faeces (epg) for nematodes and trematodes were determined by McMaster and Stoll's methods respectively. Animal-level and herd-level data were recorded by means of a questionnaire. Multi-collinearity amongst explanatory variables were assessed using $2{\times}2{\times}\;X^2$ test and one variable in a pair was dropped if $P{\leq}0.05$ formultiple logistic regression models. Association study between outcome and explanatory variables was conducted using classification tree, random forests and multiple logistic regression. A positive epg was considered as infected. Analyses were performed using $STATA^{(R)}$, version 8.0/Intercooled and $R^{(R)}$, Version 2.3.0. Seventy eight percent of the cattle were found to be infected with at least one type of helminth. Twenty four pairs of combinations of explanatory variables showed significant associations. Male animals (OR=3.3, P=.006, 95% CI=1.4, 7.7) were associated with significantly increased prevalence of nematode infection. Female cattle of the study area are mostly cross-breed, kept indoor, fed relatively good diet and not used for draught purpose. Males are used for draught purpose thereby more exposed to nematode infective stage and provided with relatively poor diet. So stressed male cattle may become more susceptible to nematode infection. All of the three statistical techniques selected gender and lumen motility as most important variables in association with nematode infection in cattle. The result of this survey can only be extrapolated to the periurban cattle population of traditional management system.

The Risk Factors for Musculoskeletal Symptoms During Work From Home Due to the Covid-19 Pandemic

  • Sjahrul Meizar Nasri;Indri Hapsari Susilowati;Bonardo Prayogo Hasiholan;Akbar Nugroho Sitanggang;Ida Ayu Gede Jyotidiwy;Nurrachmat Satria;Magda Sabrina Theofany Simanjuntak
    • Safety and Health at Work
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    • v.14 no.1
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    • pp.66-70
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    • 2023
  • Background: Online teaching and learning extend the duration of using gadgets such as mobile phones and tablets. A prolonged usage of these gadgets in a static position can lead to musculoskeletal disorders (MSD). Therefore, this study aims to identify the risk factors related to musculoskeletal symptoms while using gadgets during work from home due to the COVID-19 pandemic. Method: A cross-sectional survey with online-based questionnaires was collected from the University of Indonesia, consisting of lecturers, students, and managerial staff. The minimum number of respondents was 1,080 and was defined by stratified random sampling. Furthermore, the dependent variable was musculoskeletal symptoms, while the independent were age, gender, job position, duration, activity when using gadgets, and how to hold them. Result: Most of the respondents had mobile phones but only 16% had tablets. Furthermore, about 56.7% have used a mobile phone for more than 10 years, while about 89.7% have used a tablet for less than 10 years. A multivariate analysis found factors that were significantly associated with MSD symptoms while using a mobile phone, such as age, gender, web browsing activity, work, or college activities. These activities include doing assignments and holding the phone with two hands with two thumbs actively operating. The factors that were significantly associated with MSD symptoms when using tablets were gender, academic position, social media activity, and placing the tablet on a table with two actively working index fingers. Conclusion: Therefore, from the results of this study it is necessary to have WFH and e-learning policies to reduce MSD symptoms and enhance productivity at work.

A Meta-analysis of the Association between Blood Lead and Blood Pressure (혈중 납과 혈압의 연관성에 관한 메타분석)

  • Koh, Sang-Baek;Nam, Chung-Mo;Choi, Hong-Ryul;Cha, Bong-Suk;Park, Jong-Ku;Jee, Ho-Sung;Kim, Chun-Bae
    • Journal of Preventive Medicine and Public Health
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    • v.34 no.3
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    • pp.262-268
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    • 2001
  • Objectives : To integrate the results of studies which assess an association between blood lead and blood pressure. Methods : We surveyed the existing literature using a MEDLINE search with blood lead and blood pressure as key words, including reports published from January 1980 to December 2000. The criteria for quality evaluation were as follows: 1) the study subjects must have been workers exposed to lead, and 2) both blood pressure and blood lead must have been measured and presented with sufficient details so as to estimate or calculate the size of the association as a continuous variable. Among the 129 articles retrieved, 13 studies were selected for quantitative meta-analysis. Before the integration of each regression coefficient for the association between blood pressure and blood lead, a homogeneity test was conducted. Results : As the homogeneity of studies was rejected in a fixed effect model, we used the results in a random effect model. Our quantitative meta-analysis yielded weighted regression coefficients of blood lead associated with systolic blood pressure and diastolic blood pressure results of 0.0047 (95% confidence interval [CI]: -0.0061, 0.0155) and 0.0004 (95% CI: -0.0031, 0.0039), respectively. Conclusions : The published evidence suggested that there may be a weak positive association between blood lead and blood pressure, but the association is not significant.

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Do Low Self-Esteem and High Stress Lead to Burnout Among Health-Care Workers? Evidence From a Tertiary Hospital in Bangalore, India

  • Johnson, Avita R.;Jayappa, Rakesh;James, Manisha;Kulnu, Avono;Kovayil, Rajitha;Joseph, Bobby
    • Safety and Health at Work
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    • v.11 no.3
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    • pp.347-352
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    • 2020
  • Background: Low self-esteem can be an issue among health-care workers due to the hierarchical medical system. Health-care workers are also in a high pressure environment that can lead to stress and burnout. This study was conducted to estimate the proportion of health-care workers with low self-esteem, high stress, and burnout and the factors associated with these in a private hospital in Bangalore city. Methods: This cross-sectional study included a random sample of health-care workers of various cadres - doctors, nurses, nursing aides, technicians, and workers in ancillary departments such as laundry, dietary, central sterile supply department, and pharmacy, with probability proportional to size. Rosenberg Scale for Self-esteem, Cohen's Perceived Stress Scale, and Shirom-Melamed Burnout Measure were used as study tools. Results: Among the 306 health-care workers, there were high levels of low self-esteem (48.4%), stress (38.6%), and burnout (48.7%), with the lowest levels being among doctors. Those aged younger than 30 years had significantly lower self-esteem and greater stress. Conclusions: Health-care workers with low self-esteem were nearly thrice more likely to suffer high stress, Odds Ratio (OR) = 2.84 (1.36-5.92), and those who were stressed had more than three times higher chance of experiencing burnout, OR = 3.6 (2.02-6.55). Path analysis showed that low self-esteem among health-care workers had a direct effect on burnout, as well as an indirect effect through stress (mediator variable). This study indicates the need for screening and counseling for low self-esteem, stress, and burnout as part of a periodic medical examination of all cadres of health workers.

Reliability Analysis of a Quay Wall Constructed on the Deep-Cement-Mixed Ground(Part I: External Stability of the Improved Soil System) (심층혼합처리지반에 설치된 안벽의 신뢰성해석(Part I: 개량지반의 외부안정))

  • Huh, Jung-Won;Park, Ock-Joo;Kim, Young-Sang;Hur, Dong-Soo
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.22 no.2
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    • pp.79-87
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    • 2010
  • This is the first of the two papers dealing with reliability analyses for external and internal stability of a quay wall constructed on a special foundation. A new practical reliability analysis method is proposed in this paper to evaluate the quantitative risk associated with external stability of a quay wall constructed on the deep cement mixed ground. The method can consider uncertainties in various design variables. For the risk estimation to external stability of the improved soil-quay wall, three corresponding limit state functions of sliding, overturning and bearing capacity are fully defined by introducing concept of the secondary random variable. Three representative reliability methods, MVFOSM, FORM and MCS are then applied to evaluate the failure probabilities of the three limit state functions explicitly expressed in terms of the basic and secondary random variables. From the reliability analysis results, the failure probabilities obtained from the three approaches are very close to each other, and the sliding failure mode appears to be the most critical when the earthquake loading is under consideration.

A Comparative Study of Emotional Response to Korean Drama among Countries: With Drama 'Goblin' (한국 드라마 수용에 있어서 국가별 감정 반응 분석: 드라마 <도깨비>를 중심으로)

  • Lee, Yewon;Woo, Sungju
    • Science of Emotion and Sensibility
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    • v.20 no.4
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    • pp.31-40
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    • 2017
  • This research aims to investigate 'Hallyu' contents consumption tendency of consumers from Korea, Japan, and the United States by analyzing their emotional responses. With the development of social media, research on emotion analysis by reviewing text materials has grown. Whereas environmental variables affect consumer demand towards 'Hallyu' contents, little comparative analyses have been conducted on the emotional responses of consumers from different countries. In this research, the emotional prototype model proposed by Russell(1980) used to extract and distinguish emotional words to clarify how people in the three countries differently perceive the Korean drama "Goblin". First of all, the SNS reviews were collected during a two-month period (February 12 to April 12). Second, significant factors were identified in the collected data according to Russell's emotion model. Third, random forest was applied to organize the selected variables in the order of variable importance. Fourth, the correlations among the emotional words were compared. Lastly, the accuracy of the trained model was measured using the test dataset. The results show that "Happy" was found to be the greatest factor in Korea and in the United States and "Pleased" in Japan. Emotional words correlations showed that when watching the drama "Goblin", "passive unpleasure" was the main factor associated with individual's interest in Korea whereas "passive pleasure" was associated with individual's interest in Japan and in the United States. Based on the results, this research suggests the possibility of developing evaluation guidelines for emotional responses of different countries towards 'Hallyu' contents.