• Structural Engineering and Mechanics
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• v.92 no.1
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• pp.53-64
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• 2024

This paper presents an innovative theoretical and numerical model to predict the lateral-torsional buckling (LTB) of simply supported steel I-beams with external prestressed tendons. The model incorporates an updated prestressing force, accounting for thermal effects and various external loadings. Critical multipliers are determined by solving an eigenvalue problem derived from applying Galërkin's approach to a set of nonlinear equilibrium equations. Validation is carried out through Finite Element Method (FEM) simulations, incorporating a new expression for an equivalent thermal expansion coefficient for the beam-tendon system, addressing both mechanical and thermal deformations. The primary aim is to estimate critical conditions considering material property degradation due to fire. The present results are generally in good agreement with those provided by the literature.

• Fire Science and Engineering
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• v.27 no.3
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• pp.1-7
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• 2013

The wildland fire intensity and scale are getting bigger owing to climate change in the world. In the case of domestic, the forest is distributed over approximately 63.7 % of country and the main facilities like a industrial facility or gas facility abuts onto it. Therefore there is potential that the wildland fire is developed to a large-scale disaster. In this study, the effect distances of the radiant heat flux from the crown fire are analysed according to the change of wind velocity. The safety criteria concerning the radiant heat flux to influence on the surrounding were researched to analyse the effect distances. The criteria of radiant heat flux were chosen $5kW/m^2$, $12.5kW/m^2$, $37.5kW/m^2$. WFDS, which is an extension of NIST's Fire Dynamics Simulator, was used to consequence analysis of the forest fire. In order to apply the analysis conditions, it is researched the forest conditions that is generally distributed in domestic region. As the result, the maximum effect distances by radiant heat were showed at the horizontal and vertical direction. When the wind velocity varied from 0 to 10 m/s, the maximum effect distance increased as the wind velocity increases. Interesting point is that the maximum effect distance were shown at the wind velocity of 8 m/s. The maximum effect distance was decreased according as the fuel moisture of trees increase. This study can contribute to analyse quantitative risk about the damage effect of the surrounding facilities caused by wildland fire.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.294-299
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• 2008

The present study investigates the ventilation effects on smoke spreading with the rescue stations. Experiments for tunnel fires were carried out for n-heptane pool em at different fire locations, and the heat release rates (HRR) were obtained by addition, using the commercial code (FLUENT), the present article presents numerical results for smoke behavior in railway tunnels with rescue station, and it uses the MVHS (Modified Volumetric Heat Source) model for estimation of combustion products resulting from the fire source determined from the HRR measurement. As a result, it is found that smoke propagation is prevented successfully by the fire doors located inside the cross-passages and especially, the smoke behavior in the accident tunnel can be controlled through the ventilation system because of substantial change in smoke flow direction in the cross-passages.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1891-1892
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• 2009

• Journal of Acupuncture Research
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• v.29 no.2
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• pp.1-8
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• 2012

Objectives : This study was performed to compare the effects between Mountain-burning fire method and Heaven-penetrating cooling method on thermographic change. Materials and Methods : The experiment was conducted to 20 students of College of Oriental Medicine, Woosuk University from July 12, 2011 to July 26, 2011. Acupuncture stimulation was applied at left $Zusanli$($ST_{36}$) with Mountain-burning fire method in A group(n=10) and Heaven-penetrating cooling method in B group (n=10). To estimate thermographic change, temperature of left $Zusanli$($ST_{36}$), $Shuigou$($GV_{26}$), $Zhongwan$($CV_{12}$) were measured by DITI(digital infrared thermographic image) before acupuncture stimulation and 30sec, 10min after needle removal. Results : In A group, the temperature of left $Zusanli$($ST_{36}$), $Shuigou$($GV_{26}$), $Zhongwan$($CV_{12}$) were decreased at 30sec after needle removal, statistically. And the temperature of $Zusanli$($ST_{36}$), $Zhongwan$($CV_{12}$) were decreased at 10min after needle removal, statistically. In B group, the temperature of $Zusanli$($ST_{36}$), $Zhongwan$($CV_{12}$) were decreased at 10min after needle removal, statistically. But, there was no significant difference between two groups on thermographic change, statistically Conclusions : Acupuncture stimulation applied at left $Zusanli$($ST_{36}$) with Mountain-burning fire method has more widespread effects than Heaven-penetrating cooling method. But further studies will be needed such as thermographic change with no stimulation and with more subjects.

• Korean Journal of Hazardous Materials
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• v.2 no.1
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• pp.18-26
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• 2014

We analyzed the demand of competent authorities requiring adequate technical information for initial investigation of chemical accidents. Reflecting technical reports on chemical accident response by environmental agencies in the U.S. and Canada, we presented information on environmental diffusion and toxic effects available for the first chemical accident response. Hydrogen fluoride may have the risk potential to corrode metals and cause serious burns and eye damages. In case of inhalation or intake, it could have severe health effects. The substance itself is inflammable, but once heated, it decomposes producing corrosive and toxic fume. In case of contact with water, it can produce toxic, corrosive, flammable or explosive gases and its solution, a strong acid, may react fiercely with a base. In case of hydrogen fluoride leak, the preventive measures are to decrease steam generation in exposed sites, prevent the transfer of vapor cloud and promptly respond using inflammable substances including calcium carbonate, sodium bicarbonate, ground limestone, dried soil, dry sand, vermiculite, fly ash and powder cement. The method for fire fighting is to suppress fire with manless hose stanchions or monitor nozzles by wearing the whole body protective clothing equipped with over-pressure self-contained breathing apparatus from distance. In case of transport accident accompanied with fire, evacuation distance is 1,600m radius. In cae of fire, fire suppression needs to be performed using dry chemicals, CO₂, water spray, water fog, and alcohol-resistance foam, etc. The major symptoms by exposure route are dyspnoea, bronchitis, chemical pneumonia and pulmonary edema for respiration, skin laceration, dermatitis, burn, frostbite and erythema for eyes, and nausea, diarrhea, stomachache, and tissue destruction for digestive organs. In atmosphere, its persistency is low, and its bioaccumulation in aquatic organism is also low.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.443-450
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• 2015

The east coast of the Korean Peninsula is susceptible to fires because of the low rainfall in winter and spring, and large forest fires have occurred in this area. Lack of fresh water to combat fires has hampered efforts to prevent widespread forest fires in this region. Seawater has not been used as a suppressant because of possible detrimental effects of salt. We investigated the mobility of saline water in the forest soil and their effect on the microbial activity. Using a fire-fighting helicopter, seawater was sprayed over three plots (50 × 100 m) located on the eastern slope of the Baekdu mountain range in South Korea in April, 2011. We sampled the soil in April 4, May 20, and August 5 to determine the amount of salt that remained in the soil. The electrical conductivity value of the soil decreased to <400 μS/cm over a 1-month period. Approximately, four months after the application of seawater, the electrical conductivity value and Na⁺ content in all treatment plots did not significantly differ to those of the control plot, and total microbial activity also recovered to that of the control. Our results indicate that the amount of rainfall, soil physical-chemical properties, and topological factors may be a critical factor determining the mobility of saline water in forest soil.

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.111-117
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• 2016

The purpose of this study is to analyze the changes in turnover intention according to the level of Burn out and the mediating effect in fire officer. Higher levels of emotional labor and turnover intention resulted in higher levels of burn out(p<0.05). We used the logistic regression analysis to compare change of turnover intention according to the level of burn out. In logistic regression analysis, largest mediating factor were working days per week, the number of moving case per a day, physical condition, emotional labor and the odds(Likely to with high turnover intention) was down by 38.9% after adjustment for mediating factors. The results of this study indicate that emotional labor was negatively impact on burn out in fire officer. To reduce the burn out and the turnover intention, it is necessary to do more efforts to improve work environment (working days per week, the number of moving case per a day and emotional labor) and management personal factor(physical condition) for the fire office should be made to reduce such negative effects.

• Steel and Composite Structures
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• v.15 no.6
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• pp.679-703
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• 2013

This paper presents experimental investigations of the fundamental behavior of concrete filled steel tube (CFT) beam-columns under fire loading. A total of thirteen specimens were tested to determine the axial force-moment-curvature-temperature behavior of CFT beam-columns. The experimental approach involved the use of: (a) innovative heating and control equipment to apply thermal loading and (b) digital image correlation with close-range photogrammetry to measure the deformations (e.g., curvature) of the heated region. Each specimen was sequentially subjected to: (i) constant axial loading; (ii) thermal loading in the expected plastic hinge region following the ASTM E119 temperature-time T-t curve; and (iii) monotonically increasing flexural loading. The effects of various parameters on the strength and stiffness of CFT beam-columns were evaluated. The parameters considered were the steel tube width, width-tothickness ratio, concrete strength, maximum surface temperature of the steel tube, and the axial load level on the composite CFT section. The experimental results provide knowledge of the fundamental behavior of composite CFT beam-columns, and can be used to calibrate analytical models or macro finite element models developed for predicting behavior of CFT members and frames under fire loading.

• Advances in concrete construction
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• v.10 no.4
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• pp.289-299
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• 2020

A reliability analysis of the axial compressive load bearing capacity of postfire reinforced concrete (RC) columns strengthened with carbon fiber reinforced polymer (CFRP) sheets was presented. A 3D finite element (FE) model was built for heat transfer analysis using software ABAQUS. Based on the temperature distribution obtained from the FE analysis, the residual axial compressive load bearing capacity of RC columns was worked out using the section method. Formulas for calculating the residual axial compressive load bearing capacity of the columns after fire exposure and the axial compressive load bearing capacity of postfire columns retrofitted with CFRP sheets were developed. Then the Monte Carlo method was used to analyze the reliability of the axial compressive load bearing capacity of the RC columns retrofitted with CFRP sheets using a code developed in MATLAB. The effects of fire exposure time, load ratio, number of CFRP layers, concrete cover thickness, and longitudinal reinforcement ratio on the reliability of the axial compressive load bearing capacity of the columns after fire were investigated. The results show that within 60 minutes of fire exposure time, the reliability index of the RC columns after retrofitting with two layers of CFRPs can meet the requirements of Chinese code GB 50068 (GB 2001) for safety level II. This method is effective and accurate for the reliability analysis of the axial load bearing capacity of postfire reinforced concrete columns retrofitted with CFRP.