• 한국안전학회지
• /
• 제16권3호
• /
• pp.53-60
• /
• 2001

This paper presents a graphical method for hazard assessment of electric shock by safety criteria. For the human body to be safety actual body current should not exceed safety criteria, i.e. allowable body current. The assessment method presented in this paper is based m the safety criteria of the IEEE Standard 80 as well as the IEC 479-1. The hazard can be assessed in terms of alterable touch voltages instead of alterable body current. Thus, the hazard assessment of given electric shock condition is referred to a procedure by which the actual touch voltages are compared with the allowable (safe) touch voltages. Since the IEC 479-1 safety criteria are nonlinear, the graphical method is presented for the hazard assessment. Body current and body voltage are calculated with the allowable touch voltage. A comparison of the safety criteria of two widely accepted standards, i.e. the IEEE Std 80 End the IEC 479-1 is proposed. Also Thevenin equivalent resistance is obtained from electric shock model expressed by two-port earth-grid-foot system. On the basis of calculated results, the allowable touch voltage, the body current and the body voltage we can conduct the hazard or safety assessment and estimate the severity of electric shock.

• 한국철도학회논문집
• /
• 제8권6호
• /
• pp.533-538
• /
• 2005

In this paper we identity the hazard using HAZOP study for ATSRX which is a subsystem of the ATP system, and we study a safety management method for the mitigation of the risk to the acceptable level. ATSRX is a device that make a train which has a ATP system operate in ATS line. For this ATSRX send a induction signal with ATS system to vehicle controller. Thus ATSRX can be said a safety equipment that makes a train operate safely. In order to identify the hazard for the internal faults in ATSRX system, we employ HAZOP study method which is recommended as hazard identification in IEC 62278, RAMS requirements in railway signal, and also it provide the detail activity in IEC 61882. Thus, in this paper we perform HAZOP study based on ATSRX related standards and using the assessment of the identified hazard we study a method to guarantee the system safety through the change of the design to mitigate the risk to the acceptable level.

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

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제53권2호
• /
• pp.99-106
• /
• 2004

Train control system in LRT (Light Rail Transit) is developed as a part of "Light Rail Transit System Development Project". But there was no specific requirement representing the system safety. Because system safety must be ensured before the customization, we applied the system to a officially recognized specific procedure, such as "A Guideline to Ensure the Safety of Train Control System in Korea" that was officially announced by KNR (Korea National Railroad) in 2001. We should draw system safely requirement to guarantee system safety for the first time. In this paper, the hazard identification and analysis to derive the safety requirement on LRT train control system are carried out following the KNR guideline. To analyze hazard, we have to deduce system functions, identify related hazards, derive the effects of the hazards, analyze current risk, define the target risk of the system, and deduce the alternative plans to reduce the effects of the hazards. After the hazard analysis following the upper procedure, 30 hazards are identified and analysed. Especially detailed analysis on train collision that is a main hazard of the train control of system is specially carried out.

• 한국재난정보학회 논문집
• /
• 제13권3호
• /
• pp.376-387
• /
• 2017

본 연구의 목적은 한국 도시의 방재력 강화를 위하여 리스크 커뮤니케이션의 중요성과 방법을 고찰하고 리스크 커뮤니케이션의 도구로서 해저드 맵의 활용 및 개선의 방법을 제안하는 것이다. 한국과 일본의 해저드 맵을 비교 평가하고, 최근 일본에서 활발하게 실천되고 있는 방재 맵 만들기 사례를 분석하였다. 연구의 결과, 한국에서 작성되고 있는 해저드 맵의 활용 및 개선을 위한 5가지 안이 도출되었고, 리스크 개념의 사회적 확산이 도시 방재력 강화에 커다란 도움이 될 수 있다는 것이 파악되었다.

• 한국화재소방학회:학술대회논문집
• /
• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
• /
• pp.252-259
• /
• 1997

A method to automate hazard analysis of chemical plants is proposed in this paper. The proposed system is composed of three knowledge bases - unit knowledge base, organizational knowledge base and material knowledge base, and three hazard analysis algorithms - deviation, malfunction and accident analysis algorithm. Hazard analysis inference procedure is developed based on the actual hazard analysis procedures and accident development sequence. The proposed algorithm can perform hazard analysis in two methods and represent all conceivable types of accidents using accident analysis algorithm. In addition, it provides intermediate steps in the accident propagation, and enables the analysis result to give a useful information to hazard assessment. The proposed method is successfully demonstrated by being applied to diammonium phosphate manufacturing process. A system to automate hazard analysis is developed by using the suggested method. The developed system is expected to be useful in finding the propagation path of a fault or the cause of a malfunction as it is capable to approach causes of faults and malfunctions simultaneously.

• 한국식품영양학회지
• /
• 제35권1호
• /
• pp.51-61
• /
• 2022

This study aimed at elementary, middle, and high school dietitians who purchase ingredients for school meals. Therefore, for the study, the awareness and usage of nutritional information by 108 teachers and dieticians on 5 hazard-free meals using multivariate analysis of variance were investigated during May 18~21, 2021. Among the five questions that asked the general perceptions of school meal dietitians of 5 hazard-free meals, the perception that the "5 hazard-free foods can be easily distinguished" was the lowest. Problems were associated with using the 5 hazard-free meals such as "expensive price," "no variety in items," "disruption in the supply and demand," "inconsistent quality," and "lack of taste," in that order. Therefore, to improve 5 hazard-free school meal service, it is necessary to not only lower the price burden by providing subsidies to schools but also improve the development and distribution structure of various 5 hazard-free foods.

• Communications for Statistical Applications and Methods
• /
• 제9권3호
• /
• pp.753-763
• /
• 2002

When there is one change-point in the hazard rate model, a change-point estimator with the partial score process is suggested and compared with the previously developed estimators. The limiting distribution of the partial score process we used is a function of the Brownian bridge. Simulation study gives the comparison of change-point estimators.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제3권2호
• /
• pp.99-106
• /
• 1999

In this paper, the spline hazard rate model to the randomly censored data is introduced. The unknown hazard rate function is expressed as a linear combination of B-splines which is constrained to be linear(or constant) in tails. We determine the coefficients of the linear combination by maximizing the likelihood function. The number of knots are determined by Bayesian Information Criterion. Examples using simulated data are used to illustrate the performance of this method under presenting the random censoring.

• Journal of the Korean Data and Information Science Society
• /
• 제22권3호
• /
• pp.613-618
• /
• 2011

The proposed method is based on a penalized log partial likelihood of Cox proportional hazard model with L1-penalty. We use the iteratively reweighted least squares procedure to solve L1 penalized log partial likelihood function of Cox proportional hazard model. It provide the ecient computation including variable selection and leads to the generalized cross validation function for the model selection. Experimental results are then presented to indicate the performance of the proposed procedure.