• Structural Engineering and Mechanics
• /
• v.33 no.3
• /
• pp.325-337
• /
• 2009

Structural damage detection, damage localization and severity estimation of jacket platforms, based on calculating modal strain energy is presented in this paper. In the structure, damage often causes a loss of stiffness in some elements, so modal parameters; mode shapes and natural frequencies, in the damaged structure are different from the undamaged state. Geometrical location of damage is detected by computing modal strain energy change ratio (MSECR) for each structural element, which elements with higher MSECR are suspected to be damaged. For each suspected damaged element, by computing cross-modal strain energy (CMSE), damage severity as the stiffness reduction factor -that represented the ratios between the element stiffness changes to the undamaged element stiffness- is estimated. Numerical studies are demonstrated for a three dimensional, single bay, four stories frame of the existing jacket platform, based on the synthetic data that generated from finite element model. It is observed that this method can be used for damage detection of this kind of structures.

• Journal of the Korean Society of Safety
• /
• v.24 no.1
• /
• pp.69-77
• /
• 2009

This paper reports the aging driver traffic accident severity modeling results. For the modeling, Poisson regression approach is applied using the data set obtained from the Korea Transportation Safety Authority's simulator-based driver aptitude test results. The test items include the estimations of moving objects' speed and stopping distance, drivers' multi-task capability, and kinetic depth perception and so on. The resulting model with the response variable of equivalent property damage only(EPDO) indicated that EPDO is significantly influenced by moving objects' speed estimation and drivers' multi-task capabilities. More interestingly, a comparison with the younger driver model revealed that the degradation of such capabilities may result in severer crashes for older drivers as suggested by the higher estimated parameters for the older driver model.

• Journal of Korea Water Resources Association
• /
• v.49 no.3
• /
• pp.217-225
• /
• 2016

The drought is generally characterized by duration and severity, thus it is required to conduct the bivariate frequency analysis simultaneously considering the drought duration and severity. However, since a bivariate joint probability distribution function (JPDF) has a 3-dimensional space, it is difficult to interpret the results in practice. In order to suggest the technical solution, this study employed copula functions to estimate an JPDF, then developed conditional JPDFs on various drought durations and estimated the critical severity corresponding to non-exceedance probability. Based on the historical severe drought events, the hydrologic risks were investigated for various extreme droughts with 95% non-exceedance probability. For the drought events with 10-month duration, the most hazardous areas were decided to Gwangju, Inje, and Uljin, which have 1.3-2.0 times higher drought occurrence probabilities compared with the national average. In addition, it was observed that southern regions were much higher drought prone areas than northern and central areas.

• Safety and Health at Work
• /
• v.15 no.1
• /
• pp.87-95
• /
• 2024

Background: This study focuses on assessing occupational risk for the health hazards encountered during maintenance works (MW) in semiconductor fabrication (FAB) facilities. Objectives: The objectives of this study include: 1) identifying the primary health hazards during MW in semiconductor FAB facilities; 2) reviewing the methods used in evaluating the likelihood and severity of health hazards through occupational health risk assessment (OHRA); and 3) suggesting variables for the categorization of likelihood of exposures to health hazards and the severity of health effects associated with MW in FAB facilities. Methods: A literature review was undertaken on OHRA methodology and health hazards resulting from MW in FAB facilities. Based on this review, approaches for categorizing the exposure to health hazards and the severity of health effects related to MW were recommended. Results: Maintenance workers in FAB facilities face exposure to hazards such as debris, machinery entanglement, and airborne particles laden with various chemical components. The level of engineering and administrative control measures is suggested to assess the likelihood of simultaneous chemical and dust exposure. Qualitative key factors for mixed exposure estimation during MW include the presence of safe operational protocols, the use of air-jet machines, the presence and effectiveness of local exhaust ventilation system, chamber post-purge and cooling, and proper respirator use. Using the risk (R) and hazard (H) codes of the Globally Harmonized System alongside carcinogenic, mutagenic, or reprotoxic classifications aid in categorizing health effect severity for OHRA. Conclusion: Further research is needed to apply our proposed variables in OHRA for MW in FAB facilities and subsequently validate the findings.

• Korean Management Science Review
• /
• v.11 no.3
• /
• pp.153-167
• /
• 1994

Credibility theory has provided with a useful tool the assignment of weighting factor that reflects the credibility of the observed individual and collective experience to secure fair experience rate-,making. We review credibility models which can effectively estimate risk premiums using credibility theory, and suggest an empirical Bayed model based on the collective statistics to estimate the structural parameters. To illustrate the use of evolutionary models, the models are applied to the actual data, such as loss ratio, claim frequencies and severity, in the Korean automobile insurance. Also the possibilities of generalizations and applications of empirical models are discussed.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
• /
• 2005.09a
• /
• pp.114-118
• /
• 2005

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
• /
• 2001.06a
• /
• pp.163-166
• /
• 2001

One of the most important factors influencing the outbreak and severity of foliar diseases is the duration of wetness from dew deposition, rainfall, or irrigation. Models may provide good alternatives for assessing leaf wetness duration (LWD) without the labor, cost, and inconvenience of making measurements with sensors.(omitted)

• Structural Monitoring and Maintenance
• /
• v.9 no.2
• /
• pp.157-177
• /
• 2022

In this paper, an innovative finite element updating method is presented based on the variation wavelet transform coefficients of Auto/cross-correlations function (WTCF). The Quasi-linear sensitivity of the wavelet coefficients of the WTCF concerning the structural parameters is evaluated based on incomplete measured structural responses. The proposed algorithm is used to estimate the structural parameters of truss and plate models. By the solution of the sensitivity equation through the least-squares method, the finite element model of the structure is updated for estimation of the location and severity of structural damages simultaneously. Several damage scenarios have been considered for the studied structure. The parameter estimation results prove the high accuracy of the method considering measurement and mass modeling errors.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.4
• /
• pp.81-88
• /
• 2010

As there occurs recently and frequently a flash flood due to the climate change, a sudden local flood of great volume and short duration caused by heavy or excessive rainfall in a short period of time over a small area, it is increasing that significant danger and loss of life and property in Korea as well as the whole world. Since a flash flood usually occurs as the result of intense rainfall over small steep slope regions and has rapid runoff and debris flow, a flood rises quite quickly with little or no advance warning to prevent flood damage. The aim of this study is to quantify the severity of flash food by estimation of a flash flood index(FFI) from probability rainfall data in a study basin. FFI-D-F(FFI-Duration-Frequency) curves that present the relative severity of flash flood are developed for a study basin to provide regional basic information for the local flood forecasting and warning system particularly in ungauged catchments. It is also expected that FFI-D-F curves can be utilized for evaluation on flash flood mitigation ability and residual flood risk of both existing and planned flood control facilities.

• Journal of the Korean Data and Information Science Society
• /
• v.27 no.3
• /
• pp.599-607
• /
• 2016

The first patient of Middle East respiratory syndrome caused by a novel coronavirus infection in Korea was confirmed on May 20, 2015. After that, MERS spread over the country. In recent years, patients of MERS have been found around the Arabian Peninsula and the case fatality ratio of MERS in those area was been reported to range from 30 to 40%. In this paper, we estimate the case fatality ratio of MERS of Korea using data of 186 infections until December 1, 2015. In this study we propose a novel estimator of the case fatality ratio using information of the patients severity condition as well as records on the days of confirmation and death or recovery of the patient. By using publicly available data of the Department of Health and Human Services Centers for Disease Control, we evaluate a performance of the estimator and demonstrate a stability of the estimator from the early stage of the epidemic.