• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.535-547
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• 2021

A policy to expand the hydrogen economy has been established in Korea and the supply of FCEV is being expanded to realize a hydrogen society. Therefore, the supply of FCEV is expected to increase rapidly, and a solution to respond to accidents of FCEV is required. In this study, an experimental study was conducted to analyze the effect of the hydrogen jet flame generated by a FCEV on the inner wall of the tunnel and the characteristics of the internal radiant heat. For the experiment, the initial pressure of hydrogen tank was set to 700 bar, and the injection nozzle diameter was set to 1.8 mm in order to make the same as the conditions generated in the FCEV. In addition, a tunnel fire resistance test specimen having the same strength as the compressive strength of concrete applied to general tunnels of 40 MPa was manufactured and used in the experiment. The results were analyzed for the separation distance (2 m and 4 m) between the hydrogen release nozzle and the tunnel fire resistance test concrete. As the result, the maximum internal temperature of the test concrete was measured to 1,349.9℃ (2 m separation distance), and the radiant heat around the jet flame was up to 39.16 kW/m².

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.629-636
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• 2022

Domestic eco-friendly vehicles currently account for 5.8% of the total registered vehicles in Korea. Hydrogen vehicles, one of the representative eco-friendly vehicles, have grown rapidly as they have been expanded to the market based on the government's policy to boost the hydrogen industry. Therefore, it is time to expand the safety review of hydrogen vehicles in various directions according to the increase in supply. In this study, the effect of internal heat damage was analyzed when a jet flame was generated by a hydrogen car in a road tunnel. It was simulated using Fluent, and the amount of jet flame injection was selected in consideration of the hydrogen tank capacity of commercial hydrogen vehicles for road tunnels. In addition, the study was conducted with the direction of the jet flame and the nozzle distance from the tunnel wall as variables. From the results, when the jet flame erupted in the road tunnel, high radiant heat emission of more than 20 kW/m² was generated in most areas within ±5 m in the longitudinal direction based on the vehicle (spray nozzle) and 5 to 7 m in the lateral direction based on the adjacent tunnel wall.

• Fire Science and Engineering
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• v.23 no.1
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• pp.55-62
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• 2009

A general combustion characteristics of forcing nonpremixed jet in laminar flow rates have been conducted experimentally to investigate the effect of forcing amplitude with the resonant frequency of fuel tube. There are two patterns of the flame lift-off feature according to the velocity increasing; one has the decreasing values of forcing amplitude on the lift-off occurrence when a fuel exit velocity is increasing, while the other has the increasing values. These mean that there are the different mechanisms in the lift-off stability of forced jet diffusion flame. Especially, the characteristics of attached jet flame regime are concentrically observed with flame lengths, shapes, flow response and velocity profiles at the nozzle exit as the central figure. The notable observations are that the flame enlogation, in-homing flame and the occurrence of a vortical motion turnabout have happened according to the increase of forcing amplitude. It is understood by the velocity measurements and visualization methods that these phenomena have been relevance to an entrainment of surrounding oxygen into the fuel nozzle as the negative part of the fluctuating velocity has begun at the inner part of the fuel nozzle.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.189-199
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• 2019

In this study, behaviors of fire smoke in the operation of disaster prevention facilities (smoke damper, jet fan) in a tunnel-type structure (soundproof tunnel) were investigated numerically and results of the investigation were compared and analyzed. Through the simulation and analysis, it was found that there was a significant change in the patterns of fire smoke between the opening of the ceiling of a fire vehicle and the closing, and it was shown that the critical temperatures of PC and PMMA, main materials of a soundproof tunnel were not exceeded. In addition, the simulation of installation intervals of smoke dampers showed that the maximum temperature of a soundproof tunnel without smoke dampers was $552^{\circ}C$ while it reached $405^{\circ}C$ when smoke dampers were installed at the installation interval of 50 m. The simulation of the operation of a jet fan showed that the maximum temperature of a soundproof tunnel without a jet fan was $549^{\circ}C$ while it reached only $86^{\circ}C$ when a jet fan was operating. Therefore, it is highly expected that they could create a favorable environment for evacuation and protection of soundproofing materials, and it would be necessary to promote basic studies on tunnels serving various functions and purposes.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.623-625
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• 2004

In Electro-Luminescence Display making process, it is necessary to do high molecule patterning effectively. Recently, one of the most effective way is the patterning method using Ink-Jet head controller. To maximize the effect, it is needed to control each channel of Ink-Jet head and develop that controller. Thus, we implement the Ink-Jet Head Controller which can control the parameters of 128 fire pulses independently, improve the accuracy of patterns more than 100 times previous ones, and apply random patterns.

• Fire Science and Engineering
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• v.18 no.2
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• pp.41-48
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• 2004

We have conducted a numerical simulation under three-dimensional unsteady conditions in order to analyze the characteristics of $CO_2 $;, extinguishant transfer by varying the location of the injection nozzle, which affects the effect of a $CO_2 $;, fire fighting system used in the form of fixed systems for the marine engine room. Flow fields and $CO_2 $;, concentration fields were measured according to the location of the injection nozzle. In the case of arranging the injection nozzle on the center of the ceiling, the low-normal concentration distribution was developed along the $CO_2 $;, jet due to the downward flow created by impinging ceiling jets in the symmetric plane. The concentration line reaches its peak due to the mass transfer of $CO_2 $;, at the comer.

• Journal of the Korean Institute of Gas
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• v.22 no.5
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• pp.38-45
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• 2018

Jet fire, pool fire, and vapor cloud explosion are major accident scenarios in LPG filling station. The protection wall would mitigate radiation effect in a jet fire. In case of a pool fire, the protection wall would restrict expanding the pool area. The protection wall might both obstruct the dispersion of released vapor and protect blast overpressure in a vapor cloud explosion scenario. In this paper, An availability assessment method of the protection wall how much reduce damage to receptors is proposed. Additionally application cases are presented for the effectiveness of protection wall in the LPG filling station. The study shows that the protection wall can effectively reduce the death probabilities of receptors located behind the wall in cases of the jet fires and the vapor cloud explosions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.269-278
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• 2004

Recently, critical velocity has become a topic to attract most interests from the researchers in the field of tunnel safety. As the minimum velocity to prevent smoke backlayering during a fire, many equations have been proposed so far, and the following three equations are being considered as a standard method in Korea to calculate the capacity of smoke extraction fans. Equation by Kennedy based on Froude number, Tetzner' s equation with additional variable, ${\beta}$ to modify the Kennedy's equation, and the equation with the concept of super critical velocity by Wu are studied in this paper for the comparative purpose. A contour map describing the relationship between the critical velocity and the capacity of smoke extraction fans is proposed as a tool to calculate the number of jet fans for smoke control during a fire in the local tunnels.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.15-21
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• 2013

This study evaluated comparison of the risk according to the type of fuel by three-dimensional simulation tool(FLACS). The consequence analysis of fire explosion and jet-fire was carried out in the layout of a typical high-pressure gas filling stations using CNG, hydrogen and 30%HCNG. Under the same conditions, hydrogen had a 30kPa maximum overpressure, CNG had a 0.4kPa and HCNG had a 3.5kPa. HCNG overpressure was 7.75 times higher than the CNG measurement, but HCNG overpressure was only 11.7% compared to hydrogen. In case of flame propagation, hydrogen had a very fast propagation characteristics. On the other hand, CNG and HCNG flame propagation velocity and distance tended to be relatively safe in comparison to hydrogen. The estimated flame boundary distance by jet-fire of hydrogen was a 5.5m, CNG was a 3.4m and HCNG was a 3.9m.

• Fire Science and Engineering
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• v.12 no.2
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• pp.3-15
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• 1998

The consequence analysis for jet and flash fire accidents by the continuous release of butane vapor was performed and effects of process variables on consequences were analyzed in standard conditions. For the continuous release (87.8 kg/s) of butane vapor at 8m elevated height in the debutanizing process of the naphtha cracking plant operating at 877 kPa, 346.75 K, we found that for the jet fire accident, shape and size of the flame could be predicted and thermal radiation estimated by API model at 200m distance from release point was 1.5kW/$m^2$, and that for the flash fire accident, effect range was 11.2~120.2m. Also, simulation results showed that effects of operating pressures on consequences were larger than those of operating temperatures and results of accidents were increased with increasing operating pressures. At this time, effects of operating pressures on XUFL were smaller(about 1/10) than those on XLFL for the flash fire accident.