• Journal of the Korean Society of Safety
• /
• v.39 no.2
• /
• pp.38-43
• /
• 2024

Recently, with the expanding market for electronic devices and electric vehicles, secondary battery usage has been on the rise. Lithium-ion batteries are particularly popular due to their fast charging times and lightweight nature compared to other types of batteries. A secondary battery consists of four components: anode, cathode, electrolyte, and separator. Generally, the positive and negative electrode materials of secondary batteries are composed of an active material, a binder, and a conductive material. Acetylene Black (AB) is utilized to enhance conductivity between active material particles or metal dust collectors, preventing the binder from acting as an insulator. However, when recycling waste batteries that have been subject to high usage, there is a risk of fire and explosion accidents, as accurately identifying the characteristics of Acetylene Black dust proves to be challenging. In this study, the lower explosion limit for Acetylene Black dust with an average particle size of 0.042 ㎛ was determined to be 153.64 mg/L using a Hartmann-type dust explosion device. Notably, the dust did not explode at values below 168 mg, rendering the lower explosion limit calculation unfeasible. Analysis of explosion delay times with varying electrode gaps revealed the shortest delay time at 3 mm, with a noticeable increase in delay times for gaps of 4 mm or greater. The findings offer fundamental data for fire and explosion prevention measures in Acetylene Black waste recycling processes via a predictive model for lower explosion limits and ignition delay time.

• Journal of the Korean Society of Safety
• /
• v.26 no.4
• /
• pp.41-46
• /
• 2011

The purpose of this paper is to analyze the causes of accidents related to the 3 phase 170 kV gas insulated switchgear of a power system collected from accident sites to secure data for the prevention of similar accidents and provide important points of view regarding diagnosis for the prevention of accidents involving gas insulated switchgears. The analysis results of the causes of accidents involving gas insulated switchgears showed deformation of the manipulation lever installed at the S-phase, disconnection of the insulation rod connection, melting of the upper conductor, a damaged tulip, damage to the lower spacer and the spacer at the breaker, etc. It is believed from this result that the potential for accidents has expanded due to accumulated energy as a result of repeated deterioration. The carbonization depth of a GIS was formed near the screw (T2, T3) used to secure the lower pole of the S-phase tulip. It is not known what has caused the screws to be extruded and melted. However, it is thought that an unbalanced electromagnetic force, micro-discharge, surface discharge, etc., have occurred at that point. In addition, even though 16 years have passed since its installation, there was no installation defect, act of arson, accidental fire, etc. General periodical inspection and diagnosis failed to find the factors causing the accidents. As a system contained in a closed metal container, it has a high risk factor. Therefore, it is necessary to design, install and operate a GIS in accordance with the standard operational procedure (SOP). In addition, it is necessary to apply conversion technology for periodical SF6 gas analysis and precision safety diagnosis. It is expected that tracking and managing these changes in characteristics by recording the results on the history card will provide a significant accident prevention effect.

• Journal of the Korean Institute of Gas
• /
• v.26 no.4
• /
• pp.36-40
• /
• 2022

Recently, the biggest topic in the industry is the area of industrial safety and health management. Since city gas is flammable gas and has a high risk of fire and explosion, much effort is required to prevent serious industrial and citizenry disasters. As part of city gas safety management, this study attempted to quantitatively predict the scope and degree of damage in the event of an explosion accident caused by city gas leakage through the Consequence Analysis. As a result, there was a difference in the accident result value according to various leakage conditions such as pressure and weather conditions. Through this study, a scenario of explosion due to city gas leakage will be prepared when performing city gas safety management work and used to prepare more effective accident prevention and emergency action plans.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.26 no.6
• /
• pp.934-939
• /
• 2012

To investigate and characterize basic patterns of prehypertension. Participants were divided into three groups; ideal blood pressure(n=40), prehypertension(n=62), and stage 1 hypertension groups(n=68) according to the JNC 7 standards. They answered questionnaire asking various symptoms and received clinical examination. Data were collected and analyzed in the focus of three Zheng patterns, cold-heat, deficiency-excess and four major hypertension types. Analysis of variance was used to find differences among groups. In addition, relationship between the cold-heat trends and risk factors of hypertension were analyzed using Pearson's correlation analysis. Three risk factors; age, body mass index (BMI), and fasting blood sugar (FBS) showed intergroup differences. Statistical significances were revealed in the cold-heat pattern and two hypertension subtypes. The cold scores decreased from $4.8{\pm}1.84$ to $3.9{\pm}1.88$ and $3.7{\pm}1.27$ (p=0.022), while the heat increased from $1.9{\pm}1.32$ to $2.8{\pm}1.72$ and $2.8{\pm}1.48$ (p=0.009). Additionally two hypertension subtypes, the excessive liver fire, and the yin-yang deficiency showed significant differences. Cold had negative correlations with blood pressure (both systolic and diastolic), BMI, triglyceride, and FBS. Heat had positive correlations with systolic blood pressure, BMI, triglyceride, and FBS. Prehypertension could be characterized by using the cold-heat patterns. The cold-heat are correlated with Blood pressure, BMI, blood lipids and sugar.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.38 no.3
• /
• pp.281-293
• /
• 2020

Recently, large and small fires have been happening more often in Korea. Fire is one of the most frequent disasters along with traffic accidents in korean cities, and this frequency is closely related to the land use and the type of facilities. Therefore, in this study, the significance of fires was analyzed by considering land use, facility types, human and social factors and using 10 years of fire data in Jinju city. Based on this, OLS (Ordinary Least Square) regression analysis, SLM (Spatial Lag Model) and SEM (Spatial Error Model) using space weights, were compared and analyzed considering the location of the fire and each factor, then a statistical model with high suitability was presented. As a result, LISA analysis of spatial distribution patterns of fires in Jinju city was conducted, and it was proved that the frequency of fires was high in the order as follow, central commercial area, industrial area and residential area. Multiple regression analysis was performed by integrating demographic, social, and physical variables. Therefore, the three models were compared and analyzed by applying spatial weighting to the derived factors. As a result of the significance test, the spatial error model was analyzed to be the most significant. The facilities that have the highest correlation with fire occurrence were second type neighborhood facilities, followed by detached house, first type neighborhood facilities, number of households, and sales facilities. The results of this study are expected to be used as significant data to identify factors and manage fire safety in urban areas. Also, through the analysis of the standard deviation ellipsoid, the distribution characteristics of each facility in the residential area, industrial area, and central commercial area among the use areas were analyzed. In, the second type neighborhood facility with the highest fire risk was concentrated in the center. The results of these studies are expected to be used as useful data for identifying factors and managing fire safety in urban areas.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.1
• /
• pp.25-36
• /
• 2021

Hydrogen in hydrogen-electric vehicles has a wide range of combustion and explosion ranges, and is a combustible gas with a very fast flame propagation speed, so it has the risk of leakage, diffusion, ignition, and explosion. The fuel tank has a Thermally active Pressure Relief Device (TPRD) to reduce the risk of explosion and other explosions, and in the event of an accident, hydrogen inside the tank is released outside before an explosion or fire occurs. However, if an accident occurs in a semi-closed space such as an underground parking lot, the flow of air flow is smaller than the open space, which can cause the concentration of hydrogen gas emitted from the TPRD to accumulate above the explosion limit. Therefore, in this study, the leakage rate and concentration of hydrogen over time were analyzed according to the diameter of the nozzle of the TPRD. The diameter of the nozzle was considered to be 1 mm, 2.5 mm and 5 mm, and ccording to the diameter of the nozzle, the concentration of hydrogen in the underground parking lot increases in a faster time with the diameter of the nozzle, and the maximum value is also analyzed to be larger with the diameter of the nozzle. In underground parking lots where air currents are stagnant, hydrogen concentrations above LFL (Lowe Flammability Limit) were analyzed to be distributed around the nozzle, and it was analyzed that they did not exceed UFL (Upper Flammability Limit).

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.2048-2051
• /
• 2010

Almost all companies have paid much attention to the safety management ranging from maintenance to operation even at the stage of designing in order to prevent accidents, but fatal accidents continue to increase throughout the world. In particular, it is essential to systematically prevent such fatal accidents as fire, explosion or leakage of toxic gas at factories in order to not only protect the workers and neighbors but also prevent economic losses and environmental pollution. In addition, HRA may be used to detect the human errors which may cause accidents or trace back to any mistake on the part of workers. Usually, HRA technique is used in association with other risk assessment techniques. Moreover, it can serve to enumerate the human errors which may occur during operation or down-time or correct the existing system to reduce the mistakes. This work focuses on the coincidence of human error and mechanical failure for management of human error, and on some important performance shaping factors to propose a method for improving safety effectively of the process industries.

• The Journal of Sustainable Design and Educational Environment Research
• /
• v.11 no.3
• /
• pp.25-35
• /
• 2012

Even though newly formed schools do struggle to strengthen their security in safety, existed schools have limitations for active response against natural disaster. From analyzing the results of accident cases and states in misfortune and the safety supervision of school facilities, it is said that damages by wind, flood and fire are typical types of disaster accidents. Also, according to the basic law of misfortune and the safety supervision, it emphasizes education, training, and actions that prevent from being a victim of natural disaster. In terms of these finding, establishing disaster safety organization, control system and having students an opportunity to learn how to response against disaster should be critical component in managing disaster safety of school facilities.

• The Korean Journal of Emergency Medical Services
• /
• v.27 no.1
• /
• pp.7-18
• /
• 2023

Purpose: This study conducted a systematic literature review to analyze the factors related to suicidal ideation among firefighters. Methods: A systematic literature review was conducted to identify factors influencing suicidal ideation among firefighters, using Korean academic information search services from January to June 2022. A total of 238 articles were searched using keywords such as "firefighter," "depression," "post-traumatic stress disorder (PTSD)," "cognitive emotion regulation," "suicide," and "suicidal ideation." Among them, nine articles were selected for analysis using descriptive correlation studies. Results: It was found that the relationship between firefighter stress (PTSD) and suicidal thoughts was mediated by depression. Even if the stress level (PTSD) was high, suicidal thoughts decreased when the emotional coping level was high. Conclusion: To prevent firefighters from committing suicide, intervention programs with effective approaches to quickly identify high at-risk people and improve their emotional coping skills, should be implemented.

• Journal of Korean Society of Disaster and Security
• /
• v.14 no.3
• /
• pp.17-27
• /
• 2021

In this study, classification models were built using machine learning techniques that can classify the soil creep risk into three classes from A to C (A: risk, B: moderate, C: good). A total of six machine learning techniques were used: K-Nearest Neighbor, Support Vector Machine, Logistic Regression, Decision Tree, Random Forest, and Extreme Gradient Boosting and then their classification accuracy was analyzed using the nationwide soil creep field survey data in 2019 and 2020. As a result of classification accuracy analysis, all six methods showed excellent accuracy of 0.9 or more. The methods where numerical data were applied for data training showed better performance than the methods based on character data of field survey evaluation table. Moreover, the methods learned with the data group (R1~R4) reflecting the expert opinion had higher accuracy than the field survey evaluation score data group (C1~C4). The machine learning can be used as a tool for prediction of soil creep if high-quality data are continuously secured and updated in the future.