• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1773-1780
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• 2008

When the fire occur in the deeply underground subway station, the difficulties of passenger evacuation are expected because of many stairs to the exit. In this study, SOONGSIL-University station (7 line, 47m depth) is the one of the deepest subway stations of the each line in the Seoul metro. The numerical computational-simulation was performed for the fire driven flow in the subway station. Hot and smoke flow was analyzed from the simulation results. The proper plan of evacuation against fire was considered through the results. The fire driven flow was simulated using FDS code in which LES method was applied. The Heat Release Rate was 10MW and the ultrafast model was applied for the growing model of the fire source. The proper mesh size was determined from the characteristic length of fire size. The parallel computational method was employed to compute the flow and heat eqn's in the meshes, which are about 10,000,000, with 6cpu of the linux clustering machine.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.96-109
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• 1996

The airbag system is known to be extremely efficient for the protection in an automobile crash. The performance of the airbag system is evaluated by real tests. However, the test is very difficult and expensive. Therefore, the computational simulations are carried out with low cost. The airbag analysis is included in the anlysis of the full-car crashworthiness. The behavior of the airbag can be predicted by a thermodynamic analysis. The contact force between the occupant and the airbag is calculated from the contact volume and the pressure in the airbag. The injury rate is evaluated from the contact force and the acceleration of dummies. So far, the contact is defined after the airgag is fully inflated. In many cases, the occupant is seated in the out-of-position and the contact can happen during the inflation process. A new algorithm has been developed for the out-of-position. To describe the inflation process precisely, the airbag is defined by a sphere and a torus. The injury is evaluated for the contact happened at any time. The developed algorithm is coded and interfaced with an existing software in the public domain. The full-car modeling is adopted from the previous study which is tuned for the regular position and real tests. Numerical experimentation have been carried out with a couple of dummies in the out-of-position and the injury processes are analyzed.

• Fire Science and Engineering
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• v.19 no.1 s.57
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• pp.80-86
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• 2005

In this study effects of the natural wind and the forced smoke ejection by operating the exhaust fan are studied numerically to examine the flow characteristics of the smoke and heat generated from a fire on the platform of an underground subway station. Three different situations, including 1) the case with no natural wind and no exhaust fan operation, 2) the case with natural wind but no exhaust fan operation and 3) the case with no natural wind but exhaust fan operation, are considered for the numerical analyses. The numerical results show that the natural wind causes a rapid spread of the fire along the tunnel resulting in rapid spread of the smoke and heat over the platform which affects the escape. The operation of the exhaust fan also results in the rapid spread of smoke and heat over the platform, but the time required for reaching the safe escaping height of the smoke layer with the exhaust fan operation is much longer than that without the exhaust fan operation. The numerical results also show that the required capacity of the exhaust fan becomes larger when the effect of the natural wind is included.

• Journal of Korean Society of Transportation
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• v.20 no.3
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• pp.105-113
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• 2002

As the number of pedestrian accident increases, the reconstruction of an accident becomes important to find the source of the fault. Generally, accidents are reconstructed by the intuition of experts or primitive physics. A reconstruction method is proposed using sophisticated optimization technology. At first, a dynamic simulation model is established for the accident environment. Occupant analysis for automobile crashworthiness is employed. The situation before an accident is identified by optimization. The impact velocity and the position of the pedestrian are utilized as design variables. The design variables are found by minimizing the difference between the simulation and the real accident. The optimization process is performed by linking an occupant analysis program MADYMO to an optimization program VisualDOC. Since the involved analysis is dynamics and highly nonlinear, response surface method is selected for the optimization process. Problems are solved for various situations.

• Journal of the Korean Society for Railway
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• v.16 no.6
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• pp.447-453
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• 2013

Since PSDs(Platform Screen Doors) are set up at many subway stations, their design related to safety has become gradually important. In particular, the interference check with a running railway vehicle is the most important of performance indices because the collision between PSDs and vehicles can be dangerous for passengers in the car and on platforms. When the train comes into a station with a curvature, the passenger car has a large translational and rotational motion and the displacement is enough for coming in contact with PSD. The performance is affected by many design parameters such as rail design parameters and vehicle velocity. This study proposes dynamic analysis models for railway vehicles and rails. Some parameters were also considered in the models to determine their influence on the performance.

• Composites Research
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• v.36 no.4
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• pp.253-258
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• 2023

Although the development of transportation means has realized the right to mobility for the disabled who have difficulty in moving, it can be said that the improvement of the safety of passengers with disabilities that can occur in a car accident is lower than that of ordinary passenger seats. In particular, in the case of a rear-end collision that can occur suddenly, it is a reality that disabled passengers are vulnerable to head and neck injuries. Therefore, in this study, a multi-layer headrest foam that divides the headrest into three parts in the coronal plane was proposed to improve the head and neck injury index of disabled passengers in the vehicle in the event of a rear-end collision of a wheelchair transport vehicle. A range of stress scale factors was selected to give various compressive characteristics of the foam through low-speed rear-end collision analysis through a simple model, and GA optimization was performed by specifying the range as a parameter. Through the optimization result, the phase relationship between HIC and NIC was analyzed according to the compression characteristics of the layers. HIC responded most sensitively to the compression characteristics of the front layer and NIC responded to the compression characteristics of the mid layer, and the compression characteristics of the rear layer showed the lowest. A normal headrest and an optimized multi-layer headrest were placed in the validation model to analyze the low-speed rear-end collision sled test, and HIC and NIC were derived lower in the multi-layer headrest than in the general headrest. The compression behavior of the multi-layer headrest was also clearly shown, and it was verified that the multi-layer headrest was effective in improving the injury index of the head and neck compared to the general headrest.