• Journal of the Korean Society for Railway
• /
• v.10 no.2 s.39
• /
• pp.224-230
• /
• 2007

The performance and applicability of FDS code is analyzed for flow simulation in railway tunnel. FDS has been built in NIST(USA) for simulation of fire-driven flow. RANS and DNS's results are compared with FDS's. AJL non-linear ${\kappa}-{\epsilon}$[7,8] model is employed to calculate the turbulent flow for RANS. DNS data by Moser et al.[9] are used to prove the FDS's applicability in the near wall region. Parallel plate is used for simplified model of railway tunnel. Geometrical variables are non-dimensionalized by the height (H) of parallel plate. The length of streamwise direction is 50H and the length of spanwise direction is 5H. Selected Re numbers are 10,667 for turbulent flow and 133 for laminar low. The characteristics of turbulent boundary layer are introduced. AJL model's predictions of turbulent boundary layer are well agreed with DNS data. However, the near wall turbulent boundary layer is not well resolved by FDS code. Slip conditions are imposed on the wall but wall functions based on log-law are not employed by FDS. The heavily dense grid distribution in the near wall region is necessary to get correct flow behavior in this region for FDS.

• Fire Science and Engineering
• /
• v.21 no.3
• /
• pp.1-7
• /
• 2007

This research was conducted through demonstrating method about how high cooperation level between crisis management systems against terror in korea is now, based on both interaction level relating to cooperation relation among organization relationship theory. Through the results of analysis, People in charge against terror were widely recognizing about the need of cooperation between crisis management systems to treat terror effectively. For organic cooperation between organizations, it was suggested the politic implication that it is the most important task to build the sense of values, the behavior about cooperations in the internal phase of crisis management system.

• Fire Science and Engineering
• /
• v.17 no.3
• /
• pp.20-25
• /
• 2003

Measurements with filaments and thermocouples and computations with Oppdif and FDS were carried out to investigate the impact of flame strain, agent addition, and buoyancy on the structure and extinction of nonpremixed counterflow flames. Measurements through 2.2 s drop tests in microgravity conditions and experiments in normal gravity conditions were compared with the results of computations. For the global strain rates 7 s$^{-1}$ through 100 s$^{-1}$ , the turning point behavior in the critical nitrogen concentration at O-g was confirmed. The effects of buoyancy, that is, changes in the flame curvature and thickness were also confirmed by the computations with FDS. There was agreement in the peak flame temperature and its position between the computations and the measurements in the near extinction methane/air diffusion flames in microgravity.

• Journal of muscle and joint health
• /
• v.15 no.2
• /
• pp.175-182
• /
• 2008

Purpose: The purpose of the study was to identify low pain prevalence rate and factors affecting low back pain in emergency medical technicians. Method: A descriptive relationship research design was utilized. The participants were 74 emergency medical technicians who worked at fire stations in W and J city and agreed to participate in this study. Data were collected between April and August 2008 using a questionnaire, which included demographic factors, severity of low back pain using a visual analog scale, factors related to low back pain and health behavior, and BMI. Descriptive statistics and multiple regression were performed for data analysis. Results: 85.1% of emergency medical technicians experienced low back pain. The mean score of low back pain was relatively low (M=4.0, SD=2.33). Significant factors affecting low back pain were found to be age, marital status, exercise, hours of standing work, and BMI. These variables explained 35.1% of variance in low back pain (F=8.45, p<.001). Conclusion: These results suggest that further research is needed to develop interventions for prevention and management of low back pain among emergency medical technicians.

• Korean Institute of Interior Design Journal
• /
• v.14 no.3 s.50
• /
• pp.147-155
• /
• 2005

As multiplex theaters are increasing rapidly in number, concerns over the evacuation process in case of fire emergency are also increasing. The study investigates the users' awareness and recognition of evacuation route by the method of questionnaire, and analyzes the users' behavior in choosing the route by the simulation program called Simulex. Among others, findings indicate a vast majority of the users are unaware of the proper route in the emergency, yet anticipate to evacuate by it, instead of the entry/exit route that they are familiar with. This aspect, however, can be useful to provide the proper route of evacuation for the users, if an appropriate information is given that the entry/exit route is also used as an emergency egress. The simulation shows heavy congestion at the closer evacuation route from the exit, and distinctly less traffic at the farther means of egress. Based on this natural phenomenon, it is suggested that the emergency stair should be nearby and aligned with the exit from auditorium. Although the present building regulation only requires a minimum dimension at each route, there is a need to widen the passageway that is likely to be recognized easily and subsequently overcrowded in case of fire emergency.

• Journal of the Korean Society of Safety
• /
• v.20 no.3 s.71
• /
• pp.78-83
• /
• 2005

In this study, the evaluate characteristics of fire and explosion of MEK-PO are subjected to spontaneous ignition, flash point and explosion hazard. The minimum ignition temperature and instantaneous ignition temperature for MEK-PO were $188.5^{\circ}C\;and\;230^{\circ}C\;at\;225{\mu}L$. In addition The flash point for MEK-PO was obtained at $49^{\circ}C$. Furthermore, the maximum explosion pressure and the maximum explosion pressure rising velocity: using MCPVT (mini cup pressure vessel tester) were $10.82kgf/cm^2\;and\;33.72kgf/cm^2{\cdot}s$.

• Advances in concrete construction
• /
• v.11 no.1
• /
• pp.11-18
• /
• 2021

The present study fabricated polyvinyl alcohol (PVA) fiber-reinforced alkali-activated slag/fly ash (AASF) composites with varying mixture ratios of slag and fly ash. The thermomechanical behaviors of the AASF composites exposed to 200, 400, 600, or 800℃ were evaluated by means of compressive strength test, visual observation, and fire resistance tests. X-ray diffractometry, mercury intrusion porosimetry, and thermogravimetry tests were performed to analyze the microstructure change of the AASF composites upon exposure to high temperatures. Specimens exhibited a gradual strength loss up to 600℃, while also showing a significant decrease in the strength above 600℃. The fire resistance test revealed the occurrence of an inflection point as indicated by an increase in the internal temperature at around 200℃. In addition, specimens showed the dehydration of C-S-H gel, the presence of åkermanite, gehlenite, and anorthite upon exposure to 800℃, which is associated with the formation of macropore population with pores having diameters of 1-3 ㎛ and 20-40 ㎛. Visual observation indicated that the PVA fibers mitigated the cracking and/or spalling of the specimens upon exposure to 800℃.

• Computers and Concrete
• /
• v.33 no.3
• /
• pp.309-324
• /
• 2024

Internal curing, a widely used method for mitigating early-age shrinkage in concrete, also offers notable advantages for concrete durability. This paper explores the potential of internal curing by partial replacement of sand with fine lightweight aggregate for enhancing the behavior of high-performance concrete at elevated temperatures. Such a technique may prove economical and safe for the construction of skyscrapers, where explosive spalling of high-performance concrete in fire is a potential hazard. To reach this aim, the physico-mechanical features of internally cured high-strength concrete specimens, including mass loss, compressive strength, strain at peak stress, modulus of elasticity, stress-strain curve, toughness, and flexural strength, were investigated under different temperature exposures; and to predict some of these mechanical properties, a number of equations were proposed. Based on the experimental results, an advanced stress-strain model was proposed for internally cured high-performance concrete at different temperature levels, the results of which agreed well with the test data. It was observed that the replacement of 10% of sand with pre-wetted fine lightweight expanded clay aggregate (LECA) not only did not reduce the compressive strength at ambient temperature, but also prevented explosive spalling and could retain 20% of its ambient compressive strength after heating up to 800℃. It was then concluded that internal curing is an excellent method to enhance the performance of high-strength concrete at elevated temperatures.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.7
• /
• pp.400-409
• /
• 2017

This study aimed to examine safety consciousness and practice of safety behaviors in new police officers and investigate the relationship between them. The subjects were 81 new police officers who understood the purpose of this study and agreed to participate. The collected data were analyzed by frequency, descriptive statistics, t-test, ANOVA, and Pearson's correlation using the SPSS 22.0 program. The results of the study show that the safety consciousness of subjects was as high as 4.29 points. On the other hand, practice of safety behavior was moderate at 48.71 points. Fire safety consciousness was found to be different according to age and education level, and environmental safety action was significantly different according to gender and residence. Safety consciousness showed a significant correlation with practice of safety behavior. Based on the results, it is necessary to develop and apply more effective and practical safety related education for police officers in addition to technical and institutional aspects in order to promote safety awareness and safety behavior practice.

• Journal of Digital Convergence
• /
• v.16 no.2
• /
• pp.441-449
• /
• 2018

This study is to organize the manual for the safety accidents in campsite. For this, analyzing the types of safety accidents and reviewing the regulations of campsite. Through theoretical considerations, the problem was diagnosed and the elements of improvement were presented. Eventually, part of the Responsive and Preventative Behavior manuals were developed to organize 'Preparation Behavior Manual'. Especially, examples of safety accident prevention behavior manual were divided into: 1st, suffocation, 2nd, traffic accident, 3rd, fire, 4th, and electrical accident. "S.A.F.E.", An example, was created with the accident specific initials that were more frequently caused. Furthermore, it was emphasized that it is necessary to process of understood by the user. Subsequent studies recommended the study of cases, improvement of safety management indicators, and the specialization of campground manager and safety guard.