• Geomechanics and Engineering
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• v.21 no.2
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• pp.143-152
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• 2020

Korean society experienced successive earthquakes exceeding 5.0 magnitude in the past three years resulting in an increasing concern about earthquake stability of urban infrastructures. This study focuses on the significant aspects of earthquake risk assessment for the cut-and-cover underground railway station based on two-dimensional dynamic numerical analysis. Presented are features from a case study performed for the railway station in Seoul, South Korea. The PLAXIS2D was employed for numerical simulation and input of the earthquake ground motion was chosen from Pohang earthquake records (M5.4). The paper shows key aspects of earthquake risk for soil-structure system varying important parameters including embedded depth, supported ground information, and applied seismicity level, and then draws several meaningful conclusions from the analysis results such as seismic risk assessment.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.141-149
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• 2018

In a PCB factory, there is a corrosive chemical substance supply system that can causes major leakage accidents. These accidents can give rise to shut down the factory and do residents damage that cause enormous loss of properties. To mitigate these risks, it is necessary to provide a chemical disaster prevention system. Moreover, after considering the situation and environment of the production site, it is of great importance to build an optimal chemical accident prevention system by reflecting risk reduction measures from the point of process design and by assessing quantitative risk based on reliability data. However, because there was no established database of the reliability about facilities and equipment that can be used in the domestic, the business site and consulting organization had being used the reliability data such as USA CCPS(Center for Chemical Process Safety). In these days, Korean institutes are studying on reliability data utilization method of quantitative risk assessment for preventing chemical accidents and domestic utilization algorithms and storage bed of reliability data. This study presents samples of reliability database about the chemical substance supply system that constructed from the history data such as failure, maintenance for 10 years at a PCB factory. Also, this work proposes the safety design criteria for supply facilities of corrosive chemical substance by assessing quantitative risk on the basis of the reliability data.

• Journal of Korean Society of Transportation
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• v.31 no.4
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• pp.85-94
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• 2013

The Continuous Risk Profile (CRP) has been well known to be the most accurate and efficient among existing network screening methods. However, the classical CRP uses safety performance functions (SPFs) which require a huge investment to construct a database system. This study aims to suggest a new CRP method using average crash frequencies of homogeneous groups, instead of SPFs, as rescaling factors. Hierarchical clustering analysis is performed to classify freeway segments into homogeneous groups based on the data of AADT and number of lanes. Using the data from I-880 in California, the proposed method is compared to other several network screening methods. The results show that the proposed method decrease false positive rates while it does not produce any false negatives. The method developed in this study can be easily applied to screen freeway networks without any additional complex database systems, and contribute to the improvement of freeway safety management systems.

• Korean Journal of Construction Engineering and Management
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• v.22 no.6
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• pp.131-137
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• 2021

Since many resources are put into the work of changing the railway operation within limited time, it is important to have a specific work plan and safety management. For this reason, the work schedule is shared in advance, and parallel work is being carried out simultaneously by rail system, such as tracks, trolly wires, and signals. However, due to the nature of the transfer work, the work is carried out at night when the railway operation is finished, and many resources are put into the limited area of the operating line, so the risk of safety accidents and failure to change the operating line is recognized as high. Nevertheless, there is still not enough research done in korea regarding the operation line change construction. Therefore, this study is conducted a survey on the track exchange work of railroad for working people, and analyzed the results of the survey. Finally, a standard work process was suggested to reduce the risk of track exchange work.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.222-234
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• 2020

Autonomous vehicles are equipped with a wide rage of sensors such as GPS, RADAR, LIDAR, camera, IMU, etc. and are driven by recognizing and judging various transportation systems at intersections in the city. The accident ratio of the intersection of the autonomous vehicles is 88% of all accidents due to the limitation of prediction and judgment of an area outside the sensing distance. Not only research on non-signalized intersection collision avoidance strategies through V2V and V2I is underway, but also research on safe intersection driving in failure situations is underway, but verification and fragments through simple intersection scenarios Only typical V2V failures are presented. In this paper, we analyzed the architecture of the V2V module, analyzed the causal factors for each V2V module, and defined the failure mode. We presented intersection scenarios for various road conditions and traffic volumes. we used the ISO-26262 Part3 Process and performed HARA (Hazard Analysis and Risk Assessment) to analyze the risk of autonomous vehicle based on the simulation. We presented ASIL, which is the result of risk analysis, proposed a monitoring concept for each component of the V2V module, and presented monitoring coverage.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.541-551
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• 2020

Based on the trend, there have been numerous researches analysing the ship collision risk. However, in this scope, the navigational conditions and external environment are ignored or incompletely considered in training or/and real situation. It has been identified as a significant limitation in the navigational collision risk assessment. Therefore, a novel algorithm of the ship navigational collision risk solving system has been proposed based on basic collision risk and vulnerabilities of marine accidents. The vulnerability can increase the possibility of marine collision accidents. The factors of vulnerabilities including bad weather, tidal currents, accidents prone area, traffic congestion, operator fatigue and fishing boat operating area are involved in the fuzzy reasoning engines to evaluate the navigational conditions and environment. Fuzzy logic is employed to reason basic collision risk using Distance to Closest Point of Approach (DCPA) and Time of Closest Point of Approach (TCPA) and the degree of vulnerability in the specific coastal waterways. Analytical Hierarchy Process (AHP) method is used to obtain the integration of vulnerabilities. In this paper, vulnerability factors have been proposed to improve the collision risk assessment especially for non-SOLAS ships such as coastal operating ships and fishing vessels in practice. Simulation is implemented to validate the practicability of the designed navigational collision risk solving system.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.340-350
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• 2021

This paper proposes a decision support model for USVs to improve the accuracy of collision avoidance decision-making. It is formed by Navigation Safety Domain (NSD) and domain-based Collision Risk Index (CRI), capable of determining the collision stage and risk between multiple ships. The NSD is composed of a warning domain and a forbidden domain, which is constructed under the constraints of COLREGs (International Regulations for Preventing Collisions at Sea). The proposed domain based CRI takes the radius of NSD in various encounter situations as threshold parameters. It is found that the value of collision risk in any directions can be calculated, including actual value and risk threshold. A catamaran USV and 6 given vessels are taken as study objects to validate the proposed model. It is found that the judgment of collision stage is accurate and the azimuth range of risk exists can be detected, hence the ships can take direct and effective collision avoidance measures. According to the relation between the actual value of CRI and risk threshold, the decision support rules are summarized, and the specific terms of COLREGs to be followed in each encounter situation are given.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.447-458
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• 2017

Objective: The purpose of this study is to present the basic guidelines for preventing human error by measuring and analyzing the risk of collision perceived by the ship operator in the collision risk situation by using Korea Coast Guard patrol ships. Background: In the last 5 years, 97.5% of the causes of ship collision occurred at the sea was caused by human factors. However, the rate of marine accidents due to human error has not been reduced yet. Experiments and researches on the ship operators using the ships in actual operation are rarely performed. Method: Using two K.C.G Ships on the sea, the ship measured by 30 persons who are the subject of the ship (ship operator) when both ships approach and the relative distance gradually decreases in four encounter situations, perceived ship collision risk (PSCR) data were analyzed by statistical analysis. Results: The age and boarding career of the ship operator in the situation of ship collision risks encountered a negative impact on perceived collision risk in all four opposing encounter situations S1 ($000^{\circ}$), S2 ($045^{\circ}$), S3 ($090^{\circ}$) and S4 ($135^{\circ}$) respectively. That is, the higher the age of the ship operator, the lower the perceived risk of collision and the lower the age, the higher the risk of collision. Also, there was a difference between the average of group A (20~30 years) and group B (40~50 years) according to age of the ship operators at $000^{\circ}$, $045^{\circ}$ and $090^{\circ}$ and there was no difference at $135^{\circ}$. The mean difference of the experience of boarding career was also significantly different between group A (less than 4 years) and group B (more than 5 years), but there was no significant difference at $135^{\circ}$. Conclusion: The results showed that age and boarding career of the ship operators had negative impact on perceived collision risk and there was a difference in perceived risk of collision according to age and abundance of boarding career. As a result, by focusing on the ship operators who are in the age group of 20~30 years old and have less than 4 years of experience in boarding the ship. It is expected that the effect of prevention of marine accidents can be expected by avoiding collision avoidance. Application: The results of this study can be used as policy data of related organizations to prevent human error of ship operators and as training data of training institutes.

• Journal of the Korea Safety Management & Science
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• v.23 no.1
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• pp.23-30
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• 2021

This paper analyzed a survey of 388 general target samples to analyze the correlation between disaster safety costs and human risk factor analysis and evacuation behavior due to tunnel accidents. Considering the impact of the tunnel accident on disaster safety costs and the correlation between human evacuation and risk factors in the tunnel environment, the system should be reorganized to reflect the tunnel's basic plan, tunnel cross-section, tunnel installation.

• Journal of the Korean Society of Safety
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• v.32 no.4
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• pp.129-136
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• 2017

This study investigated the probability of possible accident through qualitative and quantitative analysis of the pressure safety valve types installed in facilities using high pressure gas to compare the installation domestic and foreign pressure safety valve standards sought the safety characteristics and safety improvement direction accordingly. The three types are the case where the shut-off valve is not installed at the front of the PSV (Case A), If a shut-off valve is installed at the front of the PSV for inspection (Case B) and If a shut-off valve is installed in front of PSV (C.S.O), PSV is installed in parallel (Case C). Three types of cases were compared with FTA and HAZOP. The results of study of the possible accidents due to over-pressure safety valve installation type, used in a high-pressure gas facilities was shows in the following order Case B > Case A > Case C. The results of analysis through FTA was in order to protect the reservoir for the possible occurring of accident the safety valve installation is depend on its type. In the FTA analysis, defects in the device itself which attached to the storage tank as a substitute for analysis of the probability of operator mistakes was Case B with as high as $2.01{\times}10^{-6}$. Depending on the type of installation analysis of Case B in order to ensure safety is prohibited to install shut-off valve and believes that mandatory regulations are needed. Rationally installing of pressure safety valve in the high pressure using facilities will be expected to improve the industrial safety from severe accidents such as high-pressure gas fire explosion.