• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.1-6
• /
• 2005

To improve safety management of railway and cope with the factors to threat technical and social safety, we need to establish railway safety management system based on analysis of hazards and assessment of risk for railway system. So we have to conduct PHA(Preliminary Hazard Analysis) first to understand weak points and factors to possibly threat safety using analysis of related data such as past accident/incident data and safety regulation and classification standards of hazards/causes of railway accidents. Therefore in this research, we led types/dangerous events/causes of risks/factors of risks from hazard log developed based on railway accident classification and hazards of railway accident. PHA model for domestic railway system will be used in risk analysis and risk assessment of railway accident.

• Communications for Statistical Applications and Methods
• /
• v.24 no.6
• /
• pp.583-604
• /
• 2017

The most popular regression model for the analysis of time-to-event data is the Cox proportional hazards model. While the model specifies a parametric relationship between the hazard function and the predictor variables, there is no specification regarding the form of the baseline hazard function. A critical assumption of the Cox model, however, is the proportional hazards assumption: when the predictor variables do not vary over time, the hazard ratio comparing any two observations is constant with respect to time. Therefore, to perform credible estimation and inference, one must first assess whether the proportional hazards assumption is reasonable. As with other regression techniques, it is also essential to examine whether appropriate functional forms of the predictor variables have been used, and whether there are any outlying or influential observations. This article reviews diagnostic methods for assessing goodness-of-fit for the Cox proportional hazards model. We illustrate these methods with a case-study using available R functions, and provide complete R code for a simulated example as a supplement.

• Journal of the Korea Safety Management & Science
• /
• v.16 no.1
• /
• pp.79-88
• /
• 2014

The rapid growth of complexity and scale can be witnessed in the design and development of modern systems. As such, the severity of damages in the occasional accidents has attracted great deal of attention lately. Although a variety of methods have so far been studied to overcome or reduce the disastrous results of hazards, the issues seem still persistent and even complicated due to the situation mentioned above. The concept of functional safety has been regarded as one approach to handling the matters by shifting up to the functions level from the consideration of each physical component itself. The outcomes of those efforts would be the international standards on functional safety such as IEC 61508 and its relatives including IEC 62278, EN 50128, ISO26262, and so on. In this paper, a method of how hazards can be analyzed to be coped with those standards has been studied. In the method proposed, the systems modeling language (SysML) is playing a key role to model and analyze the hazards from the viewpoint of functional safety. The approach taken has been applied in the analysis of the hazards in railroad systems. In spite of focusing on the individual components hazards, the method based on functional safety has analyzed them collectively with the added effect of identifying the cause originated from the interface between the functions.

• The Korean Journal of Applied Statistics
• /
• v.20 no.1
• /
• pp.39-52
• /
• 2007

Crossover trials of new drugs in the treatment of angina pectoris, which frequently use treadmill exercise test for the assessment of its efficacy, produce censored survival times. In this paper we consider analysis approaches for censored survival times from crossover trials. Previously, a stratified Cox model for paired observation and nonparametric methods have been presented as possible analysis methods. On the other hand, the differences of two survival times would produce interval-censored survival times and we propose a Cox model for interval-censored data as n alternative analysis method. Example data is analyzed in order to compare these different methods.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.9
• /
• pp.1379-1384
• /
• 2017

To guarantee safety and reliability, RAMS(Reliability Availability Maintainability and Safety) activity for a communication software in train communication network is studied. In this paper, preliminary hazard analysis in RAMS activities is studied for the communication software. Preliminary hazard analysis is done through library for communication software that the specification is defined by IEC 61375. The hazards are defined, then causes and consequence for each hazard are defined. The total 36 preliminary hazards are classified. For high severity hazards are changed to acceptable level by upgrading of system requirement specification.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.64 no.3
• /
• pp.97-103
• /
• 2015

To achieve the safety and reliability, RAMS activity for a railway signal system of Near Surface Transit is studied. In this paper, preliminary hazard analysis in RAMS activities is studied for the railway signal system of Near Surface Transit. Preliminary hazard analysis is done through automatic train protection, automatic train operation and automatic train supervision. The hazards are defined, then causes and consequence for each hazard are defined. The total 75 preliminary hazards are classified. For high severity hazards are changed to acceptable level by upgrading of system requirement specification.

• Fire Protection Technology
• /
• s.14
• /
• pp.5-12
• /
• 1993

This report is explained about test results of carbon dioxide extinguiching system components and pack-age type system (Kits) for automatic fire extinguishing system. A carbon dioxide system may be used to protect one or more hazards or hazards by menas of directional valves. Package system shall be installed to protect hazards within the limitations. The testing program was progressed by three items, external oppearance test, performance test and Total Flooding Fire Extinguishing System test. The object of this report is present the problem which apperar from the analysis of test results.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.1378-1385
• /
• 2008

The probability of landslide hazards was predicted to natural terrain around the stone relics of Jinjeon-saji area, which is located in Yangyang, Kangwon Province. As the analysis results of field investigation, laboratory test and geology and geomorphology data, the effect factors of landslides occurrence were evaluated, and then the landslides prediction map was made up by use of prediction model considering the effect factors. The susceptibility of stone relics induced by landslides was investigated as the grading classification of occurrence probability using the landslides prediction map. In the landslides prediction map, the high probability area of landslides over 70% of occurrence probability was 3,489m3, which was 10.1% of total prediction area. If landslides are occurred at the high elevation area, the three stories stone pagoda of Jinjeon-saji (National treasure No.122) and the stone lantern of Jinjeon-saji (Treasure No.439) will be collapsed by debris flow.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.185-190
• /
• 2005

In this study, a probabilistic prediction model for debris flow occurrence was developed using a logistic regression analysis. The model can be applicable to metamorphic rocks and granite area. In order to develop the prediction model, detailed field survey and laboratory soil tests were conducted both in the northern and the southern Gyeonggi province and in Sangju, Gyeongbuk province, Korea. The six landslide triggering factors were selected by a logistic regression analysis as well as several basic statistical analyses. The six factors consist of two topographic factors and four geological and geotechnical factors. The model assigns a weight value to each selected factor. The verification results reveal that the model has 86.5% of prediction accuracy. Therefore, it is possible to predict landslide occurrence in a probabilistic and quantitative manner.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.1253-1258
• /
• 2004

The system safety must be ensured before customization. There was no specific requirement representing system safety in Korea until now. So we should draw safety requirements to guarantee system safety for the first time. In this paper, the Preliminary Hazard Analysis (PHA) to derive the safety requirements on the train control system was carried out. To analyze hazard, we have to deduce system functions, identify related hazards, derive the effects of the hazards, analyze current risks, define the target risks of the system, and deduce the alternative plans to reduce the effects of the hazards. For the case study, the detailed analysis on vehicle collision that was a main hazard of the train control system was carried out.