• Journal of Applied Reliability
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• v.2 no.2
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• pp.121-133
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• 2002

This paper concerns informative censoring and some of the difficulties it creates in analysis of survival data. For analyzing censored data, misclassification of informative censoring into random censoring is often unavoidable. It is worthwhile to investigate the impact of neglecting informative censoring on the estimation of the parameters of the proportional hazards model. The proposed model includes a primary failure which can be censored informatively or randomly and a followup failure which may be censored randomly. Simulation shows that the loss is about 30% with regard to the confidence interval if we neglect the informative censoring.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.661-666
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• 2006

Interlocking signalling system plays key role as core system to manage railway operation. The core role of railway operation is to control routing, displaying signal and regulation for train. Interlocking system relate tightly to railway accident because collision and derailment is sometime taken place wrong route setting and signal displaying. Safety activity for interlocking system is inevitable to avoid the accident over its life cycle. The safety activity includes hazard identification and analysis, safety requirement allocation, safety plan, safety activity and ao on. The safety activity need a broad wide range work. In this paper, we concentrate on hazard identification for generic interlocking system and programmable electronic interlocking system and compare between two results. The hazards will be used for safety activity.

• Journal of Energy Engineering
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• v.26 no.4
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• pp.23-28
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• 2017

Hazard evaluation and FTA are performed as the first and the second step of QRA for a LNG storage tank. Hazards are identified using HAZOP. Each segment of the system is examined, and we list all possible deviations from normal operating conditions and how they might occur. The consequences on the process are assessed, and the means available to detect and correct the deviations are reviewed. The FTA is carried out to analyse the hazards identified from the HAZOP study. A top event is selected to be release of LNG. Then all combinations of individual failures that can lead to the hazardous event are shown in the logical format of the fault tree system.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.1046-1052
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• 2006

Railway works on or near the line, or trackside works, typically have high potential of accidents, as the works have to be frequently performed during the train operation. In order to reduce the risks associated with the railway trackside works effectively, a systematic risk assessment must be performed considering the hazards that contribute to the accidents. In this study, hazards are identified for railway trackside works by analysing data from Korea Railroad for accidents that have occurred between the year of 2000 and 2006. The hazard list produced in this study is expected to be effectively used for the risk assessment of the trackside works.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.402-404
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• 2000

The train control system using radio is based on the radio communication between an on-board control system and a ground control system unlike other train control systems that rely on track circuit. To realize a new train control system based on a new principle, it is important to analyze safety in a systematic manner at an early stage, and identify important factors for the system. For this reason, we think a procedure that select hazards and identify their causes and allocate safety requirements to such hazards. This paper describes this procedure to realize system safety.

• Journal of KSNVE
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• v.10 no.1
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• pp.160-167
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• 2000

This paper addresses issues encountered in using the ISO and national standard codes to assess the hazards of whole-body vibration and repeat shocks. Their assessment methods are given in ISO 2631-1 (1974, 1985, 1997) and BS 6841 (1987) that are now available to us. Two standard codes can yield unfortunately different assessment results even for a single measured vibration signal. Possible reasons for such different results are pointed out and, furthermore, related questions that should be re-examined in the future are raised in this paper.

• Korean Journal of Remote Sensing
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• v.7 no.2
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• pp.165-178
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• 1991

A geologic hazard map has been produced in the suburbs of Seoul using GIS technology to analyse the degree of geologic hazard, particularly landslides. Topographic, geologic and soil data were incorporated in a map through GIS, which enable to interpret, analyse and predict the regional geologic hazards. Potential elements causing a landslide are slope geometry, geology, groundwater table, soil property, rainfall and vegetation etc. These elements analysed in the study area were input into GIS system through cartographic simulation to produce the regional geologic hazard map. For this work, ARC/INFO(GIS) and ERDAS(IP) system were used.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.09a
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• pp.83-92
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• 2005

Fluid conductivity logging has been applied in the boreholes to identify the permeable fi:actures and estimate the origin of saline groundwater in coast area. Fluid replacement technique measures the fluid electrical conductivity with depth at different times in a well after the borehole is first washed out with different water by passing a tube to the borehole bottom. Then formation water flows into the borehole through aquifer such as permeable fractures or porous formation during ambient or pumping condition. Measured conductivity profiles with times therefore indicate the locations of permeable zone or fractures within the open hole or the fully slotted casing hole. As a result of fluid conductivity logging for three boreholes in the study area, it is interpreted that saline groundwater is caused by seawater intrusion through fractured rock, although the effect by land reclamation partially remains. We are planning the quantitative analysis to estimate the hydraulic characteristics using fluid replacement technique, and this approach might be usefully utilized for assessing the characteristics of seawater intrusion, the design of optimal pumping, and estimating the hydraulic properties in coastal aquifer.

• The Journal of Engineering Geology
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• v.15 no.2 s.42
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• pp.105-121
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• 2005

Most of the landslides triggered by intensive rainfall on natural slope occur serious damages of human beings and properties. There have been many landslides since 1991 in Gyeonggi province. The influential factors are rainfall, topography, geology and soil properties. There were 660 landslides occurred by intensive rainfall as much as 250mm at Yongin and Anseong area from Tuly 19th to luly 21st,1991 This study surveyed location, topography, geology, geometry of the landslide and rainfall at the area and analyzed occurrence characteristics of the landslides. Most of the landslides occurred on the soil layer above the bed rock. They showed changes of landslide types from translational slides at the head part to flow at the central part. The landslides have relatively small magnitude of which length is shorter than 50m. In order to identify characteristics of landslides dependent on soil conditions, geotechnical properties of soil were evaluated by laboratory tests using soil samples which were collected on slided area and not-slided area. Soil properties of the slided area show high percentage of coarse material such as gravel and sand. However, soil of the not-slided area is mainly composed of fine material such as silt and clay. Permeability coefficients of the slided area are higher than those of the not-slided area.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.2
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• pp.156-163
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• 2012

Objectives: The aim of the present study was undertaken to investigate the association between communication for chemical hazard information and characteristics of occupational safety and health managers. Subjects and Methods: We surveyed 78 occupational safety and health managers(64 male and 14 female) in 78 chemical manufacturing plants. Data were obtained using a self-reported questionnaire about size and type of company, products, communication system for chemicals and work-related characteristics of occupational safety and health managers. All analyses in this study were performed using SPSS program 12.0. Results: 64.1% of the study participants were occupational health managers aged 39.3 years on average and were graduated from college and university around 90%. 30.0% and of them were majoring in chemistry (engineering chemistry), 18.0% occupational health, 16% nursing and 30.0% others. Occupational safety managers were aged 39.4 years on average, 42.9% of them were majoring in chemistry (engineering chemistry), 21.4% environmental engineering, 10.7% occupational safety and 25% others. 86% of occupational health managers and 71.4% of occupational safety managers were classified as office job. Over 94% of the hazards information for chemicals were delivered by occupational safety and health managers, but about 28.2% workers preferred outside experts who have a profound knowledge about occupational safety and health and understandable. Occupational safety and health managers and workers had difficulties in understanding toxicological information, hazards identification, stability/reactivity, composition/information on ingredients, physical/chemical properties and ecological information. On multiple logistic regression analysis for the 16 heading of material safety data sheet, content of material safety data sheet was significantly associated with education level (odds ratio=0.286, 95% confidence interval=0.105-0.780). The hazard identification (odds ratio=3.947, 95% confidence interval=1.092-14.271) and toxicological information (odds ratio=0.841, 95% confidence interval=0.705-0.998) were significantly associated with type of occupation. Conclusions: This finding implies that the education level, type of occupation and speciality of occupational safety and health managers may affects hazards information delivery.