• Nuclear Engineering and Technology
• /
• v.52 no.12
• /
• pp.2821-2835
• /
• 2020

The phenomenon identification and ranking table (PIRT) is an important basis in the nuclear power plant (NPP) thermal-hydraulic analysis. This study focuses on the importance ranking of the input parameters when lacking the PIRT, and the target scenario is the small break loss of coolant accident (SBLOCA) in a pressurized water reactor (PWR) CPR1000. A total of 54 input parameters which might have influence on the figure of merit (FOM) were identified, and the sensitivity measure of each input on the FOM was calculated through an optimized moment-independent global sensitivity analysis method. The importance ranking orders of the parameters were transformed into the Savage scores, and the parameters were categorized based on the Savage scores. A parameter importance ranking table for the SBLOCA scenario of the CPR1000 reactor was obtained, and the influences of some important parameters at different break sizes and different accident stages were analyzed.

• Smart Structures and Systems
• /
• v.25 no.6
• /
• pp.657-668
• /
• 2020

A novel multistage approach is developed for structural model updating based on sensitivity ranking of the selected updating parameters. Modal energy-based sensitivities are formulated, and maximum-normalized indices are designed for sensitivity ranking. Based on the ranking strategy, a multistage approach is proposed, where these parameters to be corrected with similar sensitivity levels are updated simultaneously at the same stage, and the complete procedure continues sequentially at several stages, from large to small, according to the predefined levels of the updating parameters. At every single stage, a previously developed cross model cross mode (CMCM) method is used for structural model updating. The effectiveness and robustness of the multistage approach are investigated by implementing it on an offshore structure, and the performances are compared with non-multistage approach using numerical and experimental vibration information. These results demonstrate that the multistage approach is more effective for structural model updating of offshore platform structures even with limited information and measured noise. These findings serve as a preliminary strategy for structural model updating of an offshore platform in service.

• Journal of Environmental Impact Assessment
• /
• v.6 no.2
• /
• pp.113-121
• /
• 1997

LHR(Landfill Hazard Ranking Model) was developed for assessing the relative hazard of landfills by using the method of value-structured approach. LHR consists of combining a multiattribute decision-making method with a qualitative risk assessment approach. A pairwise comparision method was applied to determine weights of landfill factors related. To prove the validity of weights allocation of landfill hazard evaluation factors, sensitivity analysis was applied. Firstly, the impact on landfill hazard score according to variations of weights of landfill hazard factors was analyzed. Secondly, the impact on landfill hazard score according to conditions change of landfill hazard factors was analyzed. As a result of sensitivity analysis, LHR composite scores are largely influenced by some factors following sequential order such as waste volume, proximity to sensitive environments, containment facilities, distance from drinking water supplies, and waste toxicity. The relative order of landfill hazard evaluated by LHR is not influenced by the weights change of individual factors. Therefore, LHR seems to be a credible model to determine priorities of landfill remediation based on the vulnerability of water resources.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.05a
• /
• pp.286-290
• /
• 2007

In this paper, a new algorithm based on sensitivity method for alleviating overloads in power networks is presented to find the switching branches effectively. Preferentially the switching of shunt reactive devices such as shunt reactor and shunt capacitors is performed. If overloads are not eliminated, the ranking of switching branches is calculated according to the algorithm based on sensitivity method and the switching of the ranked branches is performed in the order of ranking until overloads are eliminated. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus test system.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.193-196
• /
• 1999

This paper presents a new systematic contingency selection and screening method for transient stability. The variation of modal synchronizing torque coefficient(MSTC) is computed using eigen-sensitivity analysis of the electromechanical oscillation modes in small signal stability model and contingencies are ranked in decreasing order of the sensitivities of the MSTC(SMSTC). The relevant clusters are identified using the eigenvector or participating factor. The proposed algorithm is tested on the KEPCO system. Ranking obtained by the SMSTC is consistent with the time simulation results by PSS/E.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.32 no.3
• /
• pp.253-267
• /
• 2022

Objectives: This study was performed to check whether the CRS (Chemical Ranking and Scoring) system is appropriate as a method to determine substances as candidates for substances subject to permission and to apply this system to the selection of candidates for substances subject to permission. Methods: A risk score was obtained by multiplying the hazard score and the exposure score and then ranking them. The hazard sub-indicators are carcinogenicity, germ cell mutagenicity, reproductive toxicity, specific target organ toxicity-repeated exposure, respiratory sensitization and endocrine disrupting chemicals. Exposure sub-indicators are persistence, bioaccumulation and emission volume. Sensitivity analysis was performed for missing values. Correlation analysis and multivariable linear regression analysis were performed among hazard, exposure and risk in order to confirm that CRS was an appropriate method. Results: As a result of the sensitivity analysis on missing values, it was confirmed that the effect on the risk ranking was not sensitive. Correlation and regression analysis confirmed that exposure had a greater effect on risk than hazard. Conclusions: The CRS system, which derives a risk score using a hazard and exposure score, is judged to be appropriate as a method for the selection of preliminary of candidates for substances subject to permission. Benzene, cadmium, nickel, and cobalt were selected as priority candidates for substances subject to permission.

• Journal of Environmental Impact Assessment
• /
• v.22 no.6
• /
• pp.677-693
• /
• 2013

IPCC showed that calculation of climate vulnerability index requires standardization process of various proxy variables for the estimation of climate exposure, sensitivity, and adaptive capacity. In this study, four different methodologies of standardization methods: Z-score, Rescaling, Ranking, and Distance to the reference country, are employed to evaluate climate vulnerability-VRI (Vulnerability-Resilience Indicator) over Korean peninsula, and the error ranges of VRI, arising from employing the different standardization are estimated. All of proxy variables are provided by CCGIS (Climate Change adaptation toolkit based on GIS) which hosts information on both past and current socio-economic data and climate and environmental IPCC SRES (A2, B1, A1B, A1T, A1FI, and A1 scenarios) climate data for the decades of 2000s, 2020s, 2050s, and 2100s. The results showed that Z-score and Rescaling methods showed statistically undistinguishable results with minor differences of spatial distribution, while Ranking and Distance to the reference country methods showed some possibility to lead the different ranking of VRI among South Korean provinces, depending on the local characteristics and reference province. The resultant VRIs calculated from different standardization methods showed Cronbach's alpha of more than 0.84, indicating that all of different methodologies were overall consistent. Similar horizontal distributions were shown with the same trends: VRI increases as province is close to the coastal region and/or it close toward lower latitude, and decreases as it is close to urbanization area. Other characteristics of the four different standardization are discussed in this study.

• Environmental Analysis Health and Toxicology
• /
• v.18 no.3
• /
• pp.183-191
• /
• 2003

Although the variety and quantities of chemicals used have been increasing, no management strategies have been developed for these chemicals in our country. Therefore, it is important to identify the hazardous characteristics of chemicals and establish reasonable and effective management plans for them. However, because insufficient resources are available to evaluate all aspects of many varieties of chemicals, studies on suitable chemical ranking and scoring (CRS) system should be performed to ensure effective screening of priority chemicals.. In addition, because most CRS systems have their own goals, it is impossible for only one generic system to be consistent with all the uses that have been developed. Therefore, priority systems should be developed with specific and clearly defined purposes in our nation. In this study, we investigated and discussed exist-ing CRS systems, and proposed several elements and principles when designing CRS systems. First of all, the system should have clearly defined goals, keep neutral, and employ simple methods. In addition, researchers need to perform sensitivity analysis to find the main variables responsible for uncertainties and use the tiered approach to compose the effective management strategies for chemicals.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.8
• /
• pp.96-103
• /
• 2008

In this paper, a new algorithm based on sensitivity method for alleviating overloads in power networks is presented to find the switching branches effectively. By applying the new sensitivity of the line flow with respect to the change of the branch impedance, both on and off switchings for alleviating overloads in power networks are performed systematically at once and an effective scheme for drawing up a plan to alleviate overloads of the lines is presented through screening a large number of line switching cases easily. The ranking of switching branches is calculated according to the new switching algorithm based on sensitivity method and the switching of the ranked branches is performed in the order of ranking until overloads are eliminated. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus test system.

• Environmental Analysis Health and Toxicology
• /
• v.20 no.4 s.51
• /
• pp.311-325
• /
• 2005

A chemical ranking and scoring system, CRS - Korea, has recently been developed and proposed to use to prioritize on a screening level the toxic chemicals for monitoring and risk assessment. As CRS-Korea requires rigorous assessments prior to its wide application, an assessment was conducted in this study by examining the contribution of individual parameter score to the final chemical score or ranking. The sensitivity of the system to the default values for various parameters of missing data was also tested. The chemical ranking/score was round to depend primarily on the score of a single parameter, i. e., the chemical release, while toxicity scores show little correlation with the priority Further analysis indicated that the dominating effect of the chemical release results from i) its multiplicative relationship with the other two exposure parameters (biodegradation and persistent) and ii) the fact that a maximum score of 10 was assigned to the chemical release parameter while 5 was assigned for all others. AE the fraction of the data that are missing exceeded $70\%$ for various toxicity parameters at compared to less than $10\%$ for exposure parameters, the sensitivity of the ranking to the default value was not significant (rank correlation coefficient = 0.98) for toxicity parameters. Bated on this assessment, an improved CRS system (CRS - Korea II) was proposed in which the impact of the chemical release was properly adjusted by changing the multiplicative relationship to additive one and the maximum score to 5. Chemical priority was derived for each of 16 provinces by using CRS-Korea II. The chemical priority was found to significantly vary among the provinces. It was concluded that not only the national chemical priority but the local chemical priority should be taken into account in setting the nationwide chemical monitoring and risk assessment strategy.