• 한국인구학
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• 제32권1호
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• pp.1-23
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• 2009

본 논문에서는 설문조사자료를 이용하여 1940년대 이후 출생한 우리나라 여성들의 연령별 출산율, 연령별 누적출산율, 결혼연령을 5개의 출생코호트별로 살펴보고 위험도 모형을 이용하여 결혼연령 및 결혼 이후 초산까지의 간격에 영향을 미치는 요인을 각각 분석하였다. 먼저 연령별 출산율을 보면 출생시기가 늦은 코호트일수록 출산율이 최고수준에 이르는 연령이 높아지는 것으로 나타났다. 한편 연령별 누적출산율은 50년대 코호트와 60년대 코호트의 경우 각각 직전 코호트에 비해 누적출산율이 크게 하락하였으나 70년대 코호트나 80년대 코호트는 60년대 코호트에 비해 누적출산율에 있어서 별다른 차이를 보이지 않았다. 결혼연령을 보면 최근의 출생코호트로 올수록 결혼연령이 높아졌다. 한편, 결혼 위험도 모형을 추정한 결과에 의하면 여성의 출생시기가 늦을수록 그리고 교육수준이 높을수록 결혼연령이 높아지는 것으로 나타났으며 특히 출생시기의 영향은 그간 진행된 여성의 취업기회의 확대와 여성의 상대적 지위의 향상 등 경제적 및 사회문화적 변화를 종합적으로 반영하는 것으로 해석된다. 다음으로 결혼 이후 첫 자녀의 출산 위험도의 경우에는 출생시기나 결혼시기 모두 유의한 영향을 미치지 않는 것으로 분석되었다. 한편, 결혼 이후에도 상당기간 취업상태를 유지한 여성의 경우 출산 위험도가 크게 낮았으며 또한 중졸 이하 학력을 가진 여성은 여타 수준의 학력을 가진 여성에 비해 출산 위험도가 낮은 것으로 나타났다. 이는 여성의 취업이나 낮은 가구소득이 출산율을 낮추는 중요한 요인임을 의미하는 것으로 중요한 정책적 시사점을 가진다.

• International Journal of Reliability and Applications
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• 제3권1호
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• pp.1-16
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• 2002

In reliability engineering, the bathtub-shaped hazard rates play an important role in survival analysis and many other applications as well. For the bathtub-shaped, initially the hazard rate decreases from a relatively high value due to manufacturing defects or infant mortality to a relatively stable middle useful life value and then slowly increases with the onset of old age or wear out. In this paper, we present a new two-parameter lifetime distribution function, called the Loglog distribution, with Vtub-shaped hazard rate function. We illustrate the usefulness of the new Vtub-shaped hazard rate function by evaluating the reliability of several helicopter parts based on the data obtained in the maintenance malfunction information reporting system database collected from October 1995 to September 1999. We develop the S-Plus add-in software tool, called Reliability and Safety Assessment (RSA), to calculate reliability measures include mean time to failure, mean residual function, and confidence Intervals of the two helicopter critical parts. We use the mean squared error to compare relative goodness of fit test of the distribution models include normal, lognormal, and Weibull within the two data sets. This research indicates that the result of the new Vtub-shaped hazard rate function is worth the extra function-complexity for a better relative fit. More application in broader validation of this conclusion is needed using other data sets for reliability modeling in a general industrial setting.

• Safety and Health at Work
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• 제12권3호
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• pp.317-323
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• 2021

Background: The surface mining industry has one of the highest fatality rates among private industries in the United States. Despite recent decreases in the fatality rates of comparable industries, the fatality rate in the surface mining industry has increased. Meanwhile, a lack of safety research in surface mining has hindered efforts to improve safety strategies in the surface mining workplace. Method: This study examined quarry workers' hazard identification skills by conducting a case study of a surface mining facility in the Mid-Atlantic region of the United States. Semistructured interviews were conducted with eight quarry workers who were employed at the mine facility. In addition to the interviews, data were collected through field notes, notes from an expert meeting with safety managers, and site photographs to explore quarry workers' safety behaviors in the workplace. Results: The results showed that quarry workers identified hazards and improved their safety performance by translating safety knowledge learned from training into practice, acquiring hands-on work experience, learning from coworkers, and sharing responsibilities among team members. Conclusion: This study contributes to understanding quarry workers' safe performance beyond what they have learned in safety training to include their interaction with other workers and hand-on experience in the workplace. This study informs practitioners in the surface mining industry to build a safe work environment as they design effective safety programs for employees.

• 대한교통학회지
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• 제12권1호
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• pp.5-24
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• 1994

The purpose of this study is to develop an accident hazard index model in order to be used for the evaluation of regional traffic safety and to develop a driver violation index model in order to identify the primary causes of traffic accidents. The accident hazard index model was developed considering the accident rates based on population and the vehicle registration. The driver violation index model was developed considering the accident rates of each item of driver violation. Using the models developed in this study, it is identified that in the provincial level analysis the degree of the traffic safety of Chungbuk, Chungnam, and Kyungbuk Province are evaluated to be low. In the county level analysis of Kyungnam Province, the degree of the traffic safety of Yangsan, Euirung, Haman, Sachun and Tongyung County are evaluated to be low. Also, it is found that the major driver violations causing accidents in the nation are driving by unlicensed drives, improper passing, and improper railroad crossing : in Kyungnam Province, improper passing is the most driver violation.

• 한국산업보건학회지
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• 제25권4호
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• pp.506-515
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• 2015

Objectives: This study was conducted to evaluate the status of hazard communication regarding dental materials among dental hygienists in the Daegu Metropolitan City and the North Gyeongsang-do Province area. Materials: A total of 310 dental hygienists were surveyed using self-administered questionnaires to investigate the status of hazard communication on dental materials and information needs. We collected instructions for use and material safety data sheets(MSDSs) for 67 dental materials frequently used at dental hospitals located in the Daegu Metropolitan City and the North Gyeongsang-do Province area. Results: The questionnaire surveys showed that only 11% of the 310 dental hygienists had knowledge of MSDS and 46.8% of respondents never read instructions for use before using materials. Just 7.4% of dental hygienists have undergone training on hazard information for dental materials. In particular, dental hygienists working at dental clinics had significantly lower response rates on knowledge of MSDS(p<0.001), reading of instructions for use(p=0.042) and training on the hazard information of dental materials(p=0.004) than those in dental hospitals or general hospitals. The essential information most desired by dental hygienists was hazard identification(82.3%) followed by first-aid measures(53.9%), handling and storage(51%), disposal considerations (49%) and toxicological information(47.1%). All dental materials were on foreign products which came from Japan(59.7%), the USA(26.9%) and Liechtenstein(13.7%). In terms of usage, 56.7% of dental materials were prosthetic, followed by conservation(31.3%), orthodontics(9%), and prevention(3%). We found that dental hygienists had accessed MSDSs for only five dental products among the 67 dental materials. The instructions for the use of the 67 dental materials provided hazard identification(64.2%), first-aid measures(83.6%), handling and storage(97%), disposal considerations(20.9%) and toxicological information(26.9%). Conclusions: Based on the results of this study, the hazard communication system for dental hygienists working at dental clinics should be improved.

• The Journal of Asian Finance, Economics and Business
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• 제6권2호
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• pp.33-44
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• 2019

The Indonesian government launched a new people's business credit program as part of a package of economic policy and deregulation. The interest rate is set lower than the average of the current loan interest rates, especially when compared with rural bank interest rates. To capture the social spatial aspects, quota sampling is applied to ten areas that divided based on the social culture. Further, the method utilized in this research is logit models, which designed to analyse the determinants of asymmetric information particularly on the rural bank and small micro enterprises. The study was conducted in East Java as the province with the largest number of rural banks in Indonesia. Based on the estimation of asymmetric information model to the respondent of rural banks and small businesses, the result shows that adverse selection can be avoided by strengthening the information about prospective borrowers. Regarding moral hazard, rural banks and small businessmen argued that the imposition of the collateral to the debtor has an important role to avoid moral hazard. Rural bank respondents stated that the KUR program with low-interest rates has affected their business development. The results implied the need of broadening the collaboration schemes between this people's business credit program and rural banks.

• Asian Pacific Journal of Cancer Prevention
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• 제15권1호
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• pp.441-447
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• 2014

Background: Multi-state models are appropriate for cancer studies such as gastrectomy which have high mortality statistics. These models can be used to better describe the natural disease process. But reaching that goal requires making assumptions like Markov and homogeneity with time. The present study aims to investigate these hypotheses. Materials and Methods: Data from 330 patients with gastric cancer undergoing surgery at Iran Cancer Institute from 1995 to 1999 were analyzed. To assess Markov assumption and time homogeneity in modeling transition rates among states of multi-state model, Cox-Snell residuals, Akaikie information criteria and Schoenfeld residuals were used, respectively. Results: The assessment of Markov assumption based on Cox-Snell residuals and Akaikie information criterion showed that Markov assumption was not held just for transition rate of relapse (state 1 ${\rightarrow}$ state 2) and for other transition rates - death hazard without relapse (state 1 ${\rightarrow}$ state 3) and death hazard with relapse (state 2 ${\rightarrow}$ state 3) - this assumption could also be made. Moreover, the assessment of time homogeneity assumption based on Schoenfeld residuals revealed that this assumption - regarding the general test and each of the variables in the model- was held just for relapse (state 1 ${\rightarrow}$ state 2) and death hazard with a relapse (state 2 ${\rightarrow}$ state 3). Conclusions: Most researchers take account of assumptions such as Markov and time homogeneity in modeling transition rates. These assumptions can make the multi-state model simpler but if these assumptions are not made, they will lead to incorrect inferences and improper fitting.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6751-6755
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• 2013

Background: Research on cancers with a high rate of mortality such as those occurring in the stomach requires using models which can provide a closer examination of disease processes and provide researchers with more accurate data. Various models have been designed based on this issue and the present study aimed at evaluating such models. Materials and Methods: Data from 330 patients with gastric cancer undergoing surgery at Iran Cancer Institute from 1995 to 1999 were analyzed. Cox-Snell Residuals and Akaike Information Criterion were used to compare parametric and semi-parametric Cox models in modeling transition rates among different states of a multi-state model. R 2.15.1 software was used for all data analyses. Results: Analysis of Cox-Snell Residuals and Akaike Information Criterion for all probable transitions among different states revealed that parametric models represented a better fitness. Log-logistic, Gompertz and Log-normal models were good choices for modeling transition rate for relapse hazard (state $1{\rightarrow}state$ 2), death hazard without a relapse (state $1{\rightarrow}state$ 3) and death hazard with a relapse (state $2{\rightarrow}state$ 3), respectively. Conclusions: Although the semi-parametric Cox model is often used by most cancer researchers in modeling transition rates of multistate models, parametric models in similar situations- as they do not need proportional hazards assumption and consider a specific statistical distribution for time to occurrence of next state in case this assumption is not made - are more credible alternatives.

• 상하수도학회지
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• 제23권3호
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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.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.547-550
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• 2006

This study is to suggest a methodology to produce landslide hazard map by combining LRA (Logistic Regression Analysis) and AHP (Analytic Hierarchy Program) Approach. Topographic factors (slope, aspect, elevation), soil drain, soil depth and land use were adopted to classify landslide hazard areas. The method was applied to a 520 $km^2$ region located in the middle of South Korea which have occurred 39 landslides during 1999 and 2003. The suggested method showed 58.9 % matching rate for the real landslide sites comparing with the classified areas of high-risk landslide while LRA and AHP showed 46.1 % and 48.7 % matching rates respectively.