• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1379-1384
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• 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
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• v.64 no.3
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• pp.97-103
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• 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.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.1
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• pp.13-18
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• 2012

'Navigable airspace' means an airspace at and above the minimum safe flight level, including airspace or flight procedures needed for safe takeoff and landing. Airspace may be established as needed and may be abolished, and in some cases may be limited to airspace management. These are absolutely based on risk assessment. Safety is the state in which the risk of harm to persons or of property damage is reduced to, and maintained at or below, an acceptable level through a continuing process of hazard identification and risk management. 'Risk' is the assessed potential for adverse consequences resulting from a hazard and 'Risk assessment' involves consideration of both the frequency and the severity of any adverse consequence. This paper proposed 'risk assessment procedure' for the structural changes of Navigable Airspaces through literature reviews relevant to manuals on airspace management and risk management.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1524-1530
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• 2008

Generally a road vehicle's wrong entry into level crossing gives rise to hazardous events, the eventual collision with a approaching train depends on the effective operation of safety barriers such a abnormal condition detecting or emergency braking. In this paper, the risk assessment models developed for the level-crossing accidents will be introduced. The definition of hazardous events and the related hazardous factors are identified by the review of the accident history and engineering interpretation of the accident behavior. A probability of the hazardous events will be evaluated by the FTA, which is based on the accident scenario. For the severity estimation, the critical factors which can effect on the consequence will be reviewed during the ETA. Finally, the number of casualty for the public(vehicle drivers) and the train passengers are converted into an equivalent fatality.

• Journal of Chest Surgery
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• v.25 no.3
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• pp.232-239
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• 1992

Acute renal failure is a well known serious complication following open heart surgery and is associated with a significant increase in morbidity and mortality rate. From 1984 to 1990, 33 patients who had acute renal failure following cardiopulmonary bypass received renal replacement therapy. PD[Peritonial dialysis] was employed in 11 patients and CAVH[continous arteriovenous hemofiltration] was employed in 22 patients. Their age ranged from 3 months to 64 years[mean 25.5$\pm$7.8 years]. The disease entities included congenital cardiac anomaly in 18, valvular heart disease in 15 and aorta disease in 2 cases. Low cardiac output was thought as a primary cause of ARF except two redo valve cases who showed severe Aemolysis k depressed renal function preoperatively. Mean serum BUN and creatinine level at the onset renal replacement therapy were 65$\pm$8 mg/dl and 3.5$\pm$0.4 mg/dl respectively, declining only after reaching peak level 7&10 days following the onset of therapy. Overall hospital mortality was 72.7%[24/33]; 81%[9/11] in PD group and 68.2% [15/22] in CAVH group respectively. The primary cause of death was low cardiac output & hemodynamic depression in all the cases. The fatal complications included multiorgan failure in 7, disseminated intravascular coagulation and sepsis in 6, neurologic damage in 4 and mediastinitis in 3 cases. No measurable differences were observed between CAVH and PD group upon consequence of acute renal failure and disease per se. The age at operation, BUN/Cr level at the onset of bypass and highest BUN/Cr level and the consequence of low output status were regarded as important risk factors, determining outcome of ARF and success of renal replacement therapy. Thus, we concluded that althoght the prognosis is largely determined by severity of low cardiac output status and other organ complication, early institution of renal replacement therapy with other intensive supportive measures could improve salvage rate in established ARF patients following CPB.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.4
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• pp.145-158
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• 2022

To manage State Safety Program (SSP) in a more integrative and proactive manner, an aviation safety authority of the state shall detect and assess the risk of emerging or hidden safety hazards before they provoke accidents or incidents(ICAO, 2018). In case of South Korea, safety risk assessment is conducted by calculating the likelihood and severity of the hazard following ICAO's safety management manual. It is reasonable to extract the safety risk likelihood by calculating the number of occurrence caused by the hazard. However, it is ambiguous to assess the safety risk severity defined as the extent of harm that might be expected to occur as a consequence of the identified hazard. In this paper, a safety risk assessment method which quantitatively calculates the risk of hazard using aviation safety data(i.e. aviation safety mandatory report, etc.) is proposed. By utilizing the proposed method, the existing process that safety risk is being subjectively assessed by safety inspectors can be supplemented. So that essential aviation safety policy decision making can be accomplished by the accurate result of safety risk assessment.

• Childhood Kidney Diseases
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• v.19 no.2
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• pp.71-78
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• 2015

The incidence of acute kidney injury (AKI) in critically ill pediatric patients has been reported as increasing to 25 %, depending on population characteristics. The etiology of AKI has changed over the last 10-20 years from primary renal disease to the renal conditions associated with systemic illness. The AKI in pediatric population is associated with increased mortality and morbidity, and prevention is needed to reduce the consequence of AKI. It is known that the most important risk factors for AKI in critically ill pediatric patients are clinical conditions to be associated with decreased renal blood flow, direct renal injury, and illness severity. Renal hypoperfusion leads to neurohormonal activation including renin-angiotensin-aldosterone system, sympathetic nervous system, antidiuretic hormone, and prostaglandins. Prolonged renal hypoperfusion can result in acute tubular necrosis. The direct renal injury can be predisposed under the condition of renal hypoperfusion, and appropriate treatment of volume depletion is important to prevent AKI. The preventable causes of AKI include contrast-induced nephropathy, hemodynamic instability, inappropriate mediation use, and multiple nephrotoxic insults. Given the evidence of preventable factors for AKI, several actions such as the use of protocol for prevention of contrast-induced nephropathy, appropriate treatment of volume depletion, vigorous treatment of sepsis, avoidance of combinations of nephrotoxic medications, and monitoring of levels of drugs should be recommended.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.3
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• pp.34-41
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• 2010

'Aviation Safety' is the state in which the risk of harm to persons or of property damage is reduced to, and maintained at or below, an acceptable level through a continuing process of hazard identification and risk management in the aviation field. 'Risk' is the assessed potential for adverse consequences resulting from a hazard and 'Risk assessment' involves consideration of both the frequency and the severity of any adverse consequence. This study focused on the risk frequency about a case airport which does not meet the 'Runway end safety area' requirement of ICAO SARPs and Korea standards and used 'RSA risk model' for estimating the risk frequency. As results of this study, risk frequency of the runway end safety areas in the case airport is higher than that of 'Runway end safety area' requirement of ICAO SARPs and Korea standards, which means that alternatives for risk frequency mitigation to a level as low as reasonably practicable is required in the case airport. The optimum solution analysed from this study is to impose restriction of aircraft operation when the runway condition is poor(icing condition) and also it snows in the case airport.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.120-125
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• 2016

Usually, a risk can be expressed as a product of likelihood and consequence of a hazard factor. Therefore, conventional risk assessment is carried out by frequency analysis and severity analysis, in turns. However, it is well known that intuitive thinking is another excellent way of thinking of human beings. This study aimed to confirm whether there exist any difference in risk assessment results derived by two different procedures - intuitive and analytical. Thus, the present study showed 10 different illustrations to 30 undergraduate students. Their responses were organized as fuzzy membership functions, and summarized as risk assessments, and compared. The results were also verified with the help of statistical hypothesis testing, which showed no significant difference. On the contrary, however, similarity measure used in fuzzy set theory was not credible as anticipated. Many cases failed to satisfy statistical hypothesis even with similarity measure higher than 0.60 so that only a trend could be accepted. In addition, a subject showed a somewhat consistent logical discrepancy in his response, which implied the necessity of sincere analysis in fuzzy formulations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.960-967
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• 2009

Power supply system of electric railway has a diversity of safety problems since it should supply high electric power to the trains moving high speed with a lot of passengers on board. This paper provides a risk assessment approach to safety management of the electric railway facilities. Construction of database from field accident information, risk assessment and management of the risk are carried out systematically to ensure the safety. The risk assessment includes hazard identification, cause analysis by FTA(Fault Tree Analysis), consequence analysis by EVA(Event Tree Analysis), and loss analysis. In terms of the severity and the probability of the accidents deduced by these analyses, the risk of the accidents is assessed by using a risk matrix designed for electric railway facilities. Based on the risk assessment, possible risk mitigation options are identified and evaluated by analyzing their impact on the risk reduction and their cost benefit ratio. The long-term safety of the electric railway facilities can be ensured by renewal of the risk assessment and the risk mitigation option analysis with continuous accident database update. The proposed approach is applied to the electric railway facilities of Korean railway based on the accident data from 2002 to 2008.