• Journal of Korean Tunnelling and Underground Space Association
• /
• v.8 no.1
• /
• pp.53-63
• /
• 2006

The objective of this study is to analyze the smoke movement and the smoke extraction efficiency using by the partial extraction system for case of tunnel fire. Based on Froude modeling and isothermal model, the 1/20 scaled model tunnel (12m long) was constructed. In the case of the upper critical velocity in the main tunnel, the smoke extraction efficiency shows almost same between group damper and distributed damper. Finally, if the fire occurs on a traffic Jam in a tunnel, it is proposed that the open dampers in partial gallery extract smoke from the main tunnel without jet fan operation. Then, after the passengers have escaped the tunnel, the jet fans work on. On the other hand, If the traffic is uncongested in the tunnel, the jet fans (smoke control system) and partial extraction system (smoke exhaust system) are operated at once in tunnel fire.

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

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.3
• /
• pp.291-297
• /
• 2014

Due to the rapid increase in demand for transportation of human and freight in modern railway systems, the CBTC system has been proposed, which is the solution for improvement of the line capacity that has been limited by the conventional track circuit based train control system. In the CBTC system, higher reliability of the communication system should be guaranteed for the safety of passengers and trains. However, due to the inherent characteristics of the wireless channel environment, performance degradations are inevitable. The diversity techniques can increase the reliability of data transmission using multiple antennas. In this paper, we investigate the performance of the STBC in the railway channel environment. Rician fading model is used for the viaduct scenarios which take important roles in the railway system. Also, considered is the Doppler effect which is an important factor in the mobile communication system. Simulations are performed to analyze the performance of the STBC in various channel environments. Results show that the performance degradation due to the phase error in viaduct scenarios is independent of the diversity order but is affected by the constellation of the modulation.

• Fire Science and Engineering
• /
• v.20 no.4 s.64
• /
• pp.58-64
• /
• 2006

Smoke extraction in tunnel fire is investigated experimently with thermal model. The object is a immersed tunnel, of which the partial extraction system exists between the tubes. The model tunnel is measured 12 m long, 0.5 m wide and 0.35 m high. The fire is simulated to pool fire and the size corresponds to full scale fire of 5 MW based on Froude modeling. The performance of partial extraction system is determined under two ventilations, natural and longitudinal ones. The results show that compared with longitudinal ventilation, the smoke extraction efficiency of natural ventilation is increased about 30% because of smoke stratification in tunnel. Also the efficiency is identical to the iso-thermal model. The results will be help for activation of the ventilation system in emergency such as in the event of tunnel fires.

• Journal of the Korea Society of Computer and Information
• /
• v.27 no.1
• /
• pp.141-148
• /
• 2022

Global climate change caused by greenhouse gases(GHG) is getting serious. To prevent this, countries around the world are regulating GHG emissions. Korea has decided to reduce GHG emissions by 37% compared to BAU (Business As Usual) by 2030. The transportation sector accounted for 18.58% of the domestic GHG emission, and roads accounted for 93.75% of the total. Public transportation is also included in the target of GHG reduction, and this study was conducted to reduce GHG emissions of bus public transportation, which can reduce GHG emissions while reducing the cost of road transportation. In this study, a simulation was conducted to predict the optimal GHG emission compared to the waiting time of passengers by adjusting the bus dispatch interval by implementing a greenhouse gas simulation model using Any Logic. If a more precise model is implemented in the future, it is expected that it will be used to reduce bus GHG emissions.

• Composites Research
• /
• v.21 no.1
• /
• pp.22-29
• /
• 2008

This paper presents the evaluation of crashworthiness and rollover characteristics of low-floor bus vehicles made of aluminum honeycomb sandwich composites with glass-fabric epoxy laminate facesheets. Crashworthiness and rollover analysis of low-floor bus was carried out using explicit finite element analysis code LS-DYNA3D with the lapse of time. Material testing was conducted to determine the input parameters for the composite laminate facesheet model, and the effective equivalent damage model for the orthotropic honeycomb core material. The crash conditions of low-floor bus were frontal accident with speed of 60km/h. Rollover analysis were conducted according to the safety rules of European standard (ECE-R66). The results showed that the survival space for driver and passengers was secured against frontal crashworthiness and rollover of low-floor bus. Also, The modified Chang-Chang failure criterion is recommended to predict the failure mode of composite structures for crashworthiness and rollover analysis.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.11
• /
• pp.1592-1598
• /
• 2022

This paper proposes an improvement system for the marginalized digital underprivileged of these services due to the lack of intuition and usability for the recently increasing number of unmanned ordering devices' interfaces and device environments. The problem with kiosk service is that it lacks intuition among design principles and cannot be used by wheelchair passengers in environments that meet general standing standards. To solve this problem, we propose a service that can use kiosk-like environments on mobile devices by photographing QR codes with mobile devices. As a result of the experiment, people in their 20s did not experience difficulties in using the existing kiosk model, but in the case of the elderly, it was difficult to use the kiosk, so they asked for help. The improved kiosk model was carried out in their 20s without difficulty, and the results showed that it was carried out without difficulty even in the case of the elderly.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.6
• /
• pp.145-150
• /
• 2023

The subway is a public transportation that many people use every day. Line 2 especially has the most crowded stations during the day. However, the risk of crush accidents is increasing due to high congestion during rush hour and this reduces the safety and comfort of passengers. Subway congestion prediction is helpful to forestall problems caused by high congestion. Therefore, this study proposes machine learning classification models that predict subway congestion during commuting time. To predict congestion in Line 2 based in machine learning, we investigate variables that affect subway congestion through previous research and collect a dataset of subway congestion on Line 2 during rush hour from PUBLIC DATA PORTAL. The proposed model is expected to establish the subway operation plane to make passengers safe and satisfied.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.6
• /
• pp.443-453
• /
• 2020

This study using the active vibration control technique attempts to alleviate numerically the airframe vibration of a UH-60A helicopter. The AVCS(Active Vibration Control System) is applied to reduce the 4/rev vibration responses at the specified locations of the UH-60A airframe. The 4/rev hub vibratory loads of the UH-60A rotor is predicted using the nonlinear flexible dynamics analysis code, DYMORE II. Various tools such as NDARC, MSC.NASTRAN, and MATLAB Simulink are used for the AVCS simulation with five CRFGs and seven accelerometers. At a flight speed of 158knots, the predicted 4/rev hub vibratory loads of UH-60A rotor excite the airframe, and then the 4/rev vibration responses at the specified airframe positions such as the pilot seat, rotor-fuselage joint, mid-cabin, and aft-cabin are calculated without and with AVCS. The 4/rev vibration responses at all the locations and directions are reduced by from 25.14 to 96.05% when AVCS is used, as compared to the baseline results without AVCS.

• Knowledge Management Research
• /
• v.24 no.2
• /
• pp.185-209
• /
• 2023

The air travel industry, which had shrunk with COVID-19, is gaining wings again. Accordingly, this study investigated whether non-verbal communication factors experienced through interaction with airline flight attendants for passengers who have traveled abroad within the past year through domestic airlines affect customer engagement and brand intimacy. A total of 285 samples were collected, and SPSS 28 and AMOS 26 programs were used to verify the reliability and validity of the research tool, the suitability of the model, and hypotheses. As a result of the empirical study analysis, it was confirmed that Paralanguage and Proxemics in non-verbal communication of flight attendants had a significant effect on customer engagement. Although it is different from the results of previous studies following changes in perspective after COVID-19, it once again confirmed the importance of airline crew communication in providing face-to-face services at the interface with passengers. In order to induce customer engagement, which is a new customer satisfaction management index. In addition, it was confirmed that customer engagement has a significant effect on brand intimacy. These results support the view that it is necessary to establish new customer management indicators of emotion and relationship marketing in the existing marketing centered on price reduction or securing loyalty. It was confirmed that interactions with flight attendants can contribute to customer engagement, and these results have important implications for those working in the air transportation industry.