• Proceedings of the KSR Conference
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• 2006.11b
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• pp.56-61
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• 2006

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 110km/h for estimating the running safety of Incheon Int'l Airport EMU. As the test results, could confirm the curving performance and running safety of Incheon Int'l Airport EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• Geomechanics and Engineering
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• v.18 no.6
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• pp.567-574
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• 2019

In order to study the effect of stress and water pressure on the permeability of fractured rock mass under three-dimensional stress conditions, a single fracture triaxial stress-seepage coupling model was established; By using the stress-seepage coupling true triaxial test system, large-scale rock specimens were taken as the research object to carry out the coupling test of stress and seepage, the fitting formula of permeability coefficient was obtained. The influence of three-dimensional stress and water pressure on the permeability coefficient of fractured rock mass was discussed. The results show that the three-dimensional stress and water pressure have a significant effect on the fracture permeability coefficient, showing a negative exponential relationship. Under certain water pressure conditions, the permeability coefficient decreases with the increase of the three-dimensional stress, and the normal principal stress plays a dominant role in the permeability. Under certain stress conditions, the permeability coefficient increases when the water pressure increases. Further analysis shows that when the gob floor rock mass is changed from high stress to unloading state, the seepage characteristics of the cracked channels will be evidently strengthened.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.536-545
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• 2024

Radioactive iodine is a representative fission product to be quantified for the safety assessment of nuclear facilities. In integral severe accident analysis codes, the iodine behavior is usually described by a multi-physical model of iodine chemistry in aqueous phase under radiation field and mass transfer through gas-liquid interface. The focus of studies on iodine source term evaluations using the combination approach is usually put on the chemical aspect, but each contribution to the iodine amount released to the environment has not been decomposed so far. In this study, we attempted the decomposition by revising the two-film theory of molecular-iodine mass transfer. The model involves an effective overall mass transfer coefficient to consider the iodine chemistry. The decomposition was performed by regarding the coefficient as a product of two functions of pH and the overall mass transfer coefficient for molecular iodine. The procedure was applied to the EPICUR experiment and suppression chamber in BWR.

• Journal of the Korean Society of Safety
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• v.30 no.5
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• pp.52-58
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• 2015

Although lots of safety inspection and precision safety diagnosis have been conducted on concrete retaining wall, there is no comprehensive analysis on the basis of the accumulated data associated with the statistic. Especially, the concentrated management is necessary on the evaluation items that cause critical damages for the efficient performance. In this regard, this study conducted a correlation analysis between the 18 condition evaluation items and defect index for the concrete retaining wall as well as how each item affects the final defect index as much as in the manual. As a result, correlation coefficient between sliding and overturning was 0.601, which means that they have a strong correlation, and the most influential item on defect index is the condition of drainage that scored the 0.750 correlation coefficient. In addition, as a result of regression analysis, the condition of drainage with the 0.683 correlation coefficient has a strong correlation with the defect index. If the condition evaluation items are integrated or readjusted based on the results of the statistical analysis in this study, the more efficient and accurate maintenance will be possible.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.5
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• pp.161-168
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• 2019

Construction industry is becoming more advanced, but safety accidents are not decreasing and unsafe act (UA) and human errors (HE) are the main causes of safety accidents. Therefore, this study aims to analyze the relationships between unsafe acts and human errors for construction accident prevents. Specifically, the Correlation Analysis is used to quantify 24 combinations of the relationship between the UA and HE. Then, the Kano Model, and Timko Satisfied Coefficient was utilized to find 6 combinations for construction accident prevention plans. As the result of Timko Satisfied Coefficient, an interview was conducted with three safety managers and 6 safety prevention plan is proposed. Through these results, it is expected that the combination of 24 accidents will be basic data of safety management. Especially, the proposed safety prevention plans considering the characteristics of 6 combinations with high correlation can contribute to prevention of safety accidents at the construction site.

• Journal of the Korean Society of Safety
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• v.33 no.4
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• pp.78-83
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• 2018

Previous researches on the analysis of algae concentration were restricted to applying single-valued decay coefficient during simulation period, and the accuracy as well as the applicability were severely challenged. In this study, an equivalent tracking method of decay coefficient was proposed by introducing the time-series decay coefficients and restart option. Dye module in EFDC model was employed to route the temporal variation of Chl-a concentration. It was shown that the simulation results can be significantly improved up to 46% when the equivalent tracking method was activated.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.743-748
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• 2007

The important factor to evaluate the running safety of a railway vehicle would be the interaction force between wheel and rail(derailment coefficient), for which is one of important factors to check the running safety of a railway vehicle that may cause a tragic accident. Especially, a newly developed vehicle that first runs commercially requires necessarily the measurement and evaluation of derailment coefficient for securing the safety of a vehicle while measuring the derailment coefficient in view of securing running safety could be the more important factor than any other factors. In this paper, examined possibility that can forecast derailment possibility to behavior of only vibration and displacement by measuring vibration acceleration and displacement in vehicles that travel actuality rail track, and compares with data of wheel load/lateral force result.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.481-484
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• 2008

The important factor to evaluate the running safety of a railway vehicle would be the interaction force between wheel and rail(derailment coefficient), for which is one of important factors to check the running safety of a railway vehicle that may cause a tragic accident. Element that analyze derailment coefficient is consisted of wheel load and lateral force. In this paper, studied about method that calculate vertical force(wheel load) by bending load of axle in rolling stocks.

• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.701-705
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• 2011

The paper reviews Cronbaha's coefficient to measure a single source of error. On the contrary to classical measurement theory, the generalizability study can be used in the social survey design to calculate Generalizability Index (GI) and Dependability Index (DI) for measuring multiple sources of errors of behavior evaluation. The study proposes application guidelines to implement R:($A{\times}B$) mixed models that are composed of random factor and fixed factor.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.91-99
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• 2010

In this study, the advanced numerical algorithm is developed which can performed the static and dynamic stochastic finite element analysis by considering the effect of uncertainties included in the member stiffness of steel cable-stayed bridges and seismic load. After conducting the linear and nonlinear initial shape analysis, the advanced numerical algorithm is the assessment tool which can performed structural the response analysis considering the static linearity and non-linearity of before or after induced intial tensile force, and examined the reliability assessment more efficiently. The verification of the developed numerical algorithm is evaluated by analyzing the regression analysis and coefficient of correlation using the direct monte carlo simulation. Also, the dynamic response characteristic and coefficient of variation of the steel cable-stayed bridge is calculated by considering the uncertainty of random variables using the developed numerical algorithm. In addition, the quantitative structural safety of the steel cable-stayed bridges is evaluated by conducting the reliability assessment based upon the dynamic stochastic finite element analysis result.