• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.2
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• pp.174-179
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• 2015

Failure Mode and Effects Analysis (FMEA) has been used by Dynamic Positioning (DP) system for risk and reliability analysis. However, there are limitations associated with its implementation in offshore project. 1) since the failure data measured from the SCADA system is missing or unreliable, assessments of Severity, Occurrence, Detection are based on expert's knowledge; 2) it is not easy for experts to precisely evaluate the three risk factors. The risk factors are often expressed in a linguistic way. 3) the relative importance among three risk factors are rarely even considered. To solve these problems and improve the effectiveness of the traditional FMEA, we suggest a Fuzzy-FMEA method for risk and failure mode analysis in Dynamic Positioning System of offshore. The information gathered from DP FMEA report and DP FMEA Proving Trials is expressed using fuzzy linguistic terms. The proposed method is applied to an offshore Dynamic Positioning system, and the results are compared with traditional FMEA.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.192-207
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• 2023

Commercialization of level-4 (Lv.4) autonomous driving applications requires the definition of a safe road environment under which autonomous vehicles can operate safely. Thus, a risk assessment model is required to determine whether the operation of autonomous vehicles can provide safety to is sufficiently prepared for future real-life traffic problems. Although the risk factors of autonomous vehicles were selected and graded, the decision-making method was applied as qualitative data using a survey of experts in the field of autonomous driving due to the cause of the accident and difficulty in obtaining autonomous driving data. The fuzzy linguistic representation of decision-makers and the fuzzy analytic hierarchy process (AHP), which converts uncertainty into quantitative figures, were implemented to compensate for the AHP shortcomings of the multi-standard decision-making technique. Through the process of deriving the weights of the upper and lower attributes, the road alignment, which is a physical infrastructure, was analyzed as the most important risk factor in the operation risk of autonomous vehicles. In addition, the operation risk of autonomous vehicles was derived through the example of the risk of operating autonomous vehicles for the 5 areas to be evaluated.

• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.360-373
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• 2017

The BTO-a projects is the types, which has a demand risk among the type of PPP projects in Korea. When demand risk is realized, private investor encounters financial difficulties due to lower revenue than its expectation and the government may also have a problem in stable infrastructure operation. In this regards, the government has applied various risk sharing policies in response to demand risk. However, the amount of government's risk sharing is the government's contingent liabilities as a result of demand uncertainty, and it fails to be quantified by the conventional NPV method of expressing in the text of the concession agreement. The purpose of this study is to estimate the value of investment risk sharing by the government considering the demand risk in the profit sharing system (BTO-a) introduced in 2015 as one of the demand risk sharing policy. The investment risk sharing will take the form of options in finance. Private investors have the right to claim subsidies from the government when their revenue declines, while the government has the obligation to pay subsidies under certain conditions. In this study, we have established a methodology for estimating the value of investment risk sharing by using the Black - Scholes option pricing model and examined the appropriateness of the results through case studies. As a result of the analysis, the value of investment risk sharing is estimated to be 12 billion won, which is about 4% of the investment cost of the private investment. In other words, it can be seen that the government will invest 12 billion won in financial support by sharing the investment risk. The option value when assuming the traffic volume risk as a random variable from the case studies is derived as an average of 12.2 billion won and a standard deviation of 3.67 billion won. As a result of the cumulative distribution, the option value of the 90% probability interval will be determined within the range of 6.9 to 18.8 billion won. The method proposed in this study is expected to help government and private investors understand the better risk analysis and economic value of better for investment risk sharing under the uncertainty of future demand.

• Journal of the Korea Convergence Society
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• v.11 no.8
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• pp.229-236
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• 2020

This study was conducted to identify the influence of the convergent lifestyles of the elderly consisting of physical exercise, smoking, drinking and social participation and the types of social participation on the risk of cognitive decline by using the 6th Korean Longitudinal Study of Ageing(KLoSA). Total 4,298 people aged 65 or older were included. Results show that all of lifestyle factors are significantly effected to prevent cognitive decline, social participation was derived as the most important explanatory variable to lower the risk of cognitive decline. In addition, participating in the religious groups, ascriptive groups, and expressive groups lowered the risk of cognitive decline. Therefore, active support at the community and policy for improving the convergent lifestyle of the elderly are needed.

• Journal of the Korean Institute of Gas
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• v.22 no.6
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• pp.129-135
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• 2018

For efficiently safety management of city gas pipelines, the City-gas Pipeline Management System(CPMS) has been developed to systematically manage and analyze the data collected from 33 city gas companies and to effectively perform internal and external affairs related to gas safety management. The piping information data uploaded to the CPMS is ranked the risk according to the criteria specified in the KGS Code, and the safety management of the piping has performed close inspection according to the risk ranking. However, the criteria for deriving the risk ranking is very simple and lacks relevant grounds, and the reliability for the determination of the close inspection pipeline is no high due to the redundant rank. Therefore, we developed a risk assessment program based on the Reliability Based Design Assessment(RBDA) methodology and tried to derive a reasonable risk ranking by linking it with the CPMS system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.67-74
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• 2011

In this paper, we presented a dynamic cyber attack tree which can describe an attack scenario flexibly for an active cyber attack model could be detected complex and transformed attack method. An attack tree provides a formal and methodical route of describing the security safeguard on varying attacks against network system. The existent attack tree can describe attack scenario as using vertex, edge and composition. But an attack tree has the limitations to express complex and new attack due to the restriction of attack tree's attributes. We solved the limitations of the existent attack tree as adding an threat occurrence probability and 2 components of composition in the attributes. Firstly, we improved the flexibility to describe complex and transformed attack method, and reduced the ambiguity of attack sequence, as reinforcing composition. And we can identify the risk level of attack at each attack phase from child node to parent node as adding an threat occurrence probability.

• Journal of Navigation and Port Research
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• v.40 no.1
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• pp.27-34
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• 2016

For the prevention of marine casualties, international bodies have mainly focused on strengthening ship's stability and design, maritime education and training, and improving maritime traffic environment. Statistics analysis on marine casualties showed that most of casualties occurred in coastal waters, especially by human elements. In order to review the conformity of existing prevention measures with the result of the statistics analysis, the IMO's SHELL model was applied to the established measures. As a result, ergonomic approaches were needed for the prevention of human errors in coastal waters, so that the priority should be given to the interface between ship's operator and navigational environment. For this study, Rasmussen's SRK pyramid, which showed decision making mechanism of human, and the US Coast Guard's investigation manual on marine casualties concerning the collapse of safe maritime transportation system were reviewed, and the merits and demerits within the risk assessment tools such as IWRAP, PAWSA, ES model, PARK model, and NURI model were also studied. Although the effectiveness of the existing risk assessment models was proved in ports and approaching channels, it is concluded that the need of new models for converting Korean seafarers' qualitative risk to quantitative risk was proposed so as to print hazard maps which make seafarers instinctively recognize comparative hazard levels of coastal waters.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.123-130
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• 2008

Flight safety analysis, which includes risk estimation for the various abnormal flight modes in addition to normal flight, has to be performed necessarily to guarantee launch safety for the operation of space launch vehicles. For this purpose, a dedicated system has been developed such that all the necessary repetitive computations, result reports, and graphical presentations can be performed inside a single system for user convenience. In addition, the developed system is capable of representing computed results on a three dimensional Earth for the realistic presentation. The developed Flight Safety Analysis System will be employed for the launch operation of Korea Satellite Launch Vehicle-I.

• The Korean Journal of Applied Statistics
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• v.23 no.4
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• pp.715-724
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• 2010

Recurrent event data occurs when a subject experience the event of interest several times and has been found in biomedical studies, sociology and engineering. Several diverse approaches have been applied to analyze the recurrent events (Cook and Lawless, 2007). In this study, we analyzed the YTOP(Young Traffic Offenders Program) dataset which consists of 192 drivers with conviction dates by speeding violation and traffic rule violation. We consider a subject-specific effect, frailty, to reflect the individual's driving behavior and extend to time-varying frailty effect. Another feature of this study is about the redefinition of risk set. During the study, subject may be under suspension and this period is regarded as non-risk period. Thus the risk variables are reformatted according to suspension and termination time.

• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.48-53
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• 2006

In case of fire and explosion which resulted from LP gas release of LPG vessel retail store, the populated area such as apartment complex is supposed to be damaged either partially or totally. To estimate the damage of LP gas explosion, we conducted quantitative risk analysis procedure as has been recommended by AIChE/CCPS. For incident scenario selection, event tree analysis was proposed. TNT equivalent method, SAFER Trace v.8.0 and probit model were also used for consequence analysis. The various methods and analyses which were performed in this study are presented with the effect zones in the layout.