• The Journal of The Korea Institute of Intelligent Transport Systems
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• 제16권4호
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• pp.54-63
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• 2017

With the aim of promoting the use of metropolitan railways, the present research developed a mode choice model for evaluating its competitiveness against passenger cars. A case study was carried out with Gyeongeui and Joongang line, and the area of interest was the direct operating railway between Ilsan and Guri station where the two lines intersect. The mode choice model was a disaggregate behavior model which used Stated Preference (SP) survey data, and the plot of competition was between private passenger cars and express trains. As a result, the mode choice model was established, and this model was used to analyze characteristics of passengers' time value and elasticity. It was shown that reducing travel time is more efficient than reducing travel cost when it comes to operating express trains in metropolitan railways. Therefore, policies designed for activating the use of metropolitan railways should expand direct operating service of individual lines and run more express trains in order to minimize transfer and in-vehicle time.

• Journal of the Korean Society for Railway
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• 제14권2호
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• pp.109-115
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• 2011

The shoe brake of the KTX is used in low speed when the electric brake is not effective. The main purpose of the shoe brake is to stop the train to a desired stop point at the station. Lots of defects have been encountered in the shoe brake unit since the KTX started its operation. To improve the reliability of shoe brake unit of the KTX power car, first of all, failure modes of the KTX shoe brake unit were analyzed. Main failure modes are cracks in the shoe friction material and fracture in the welded joints of the shoe backing steel structure. Several methods to remove the defects of the shoe brake unit were proposed and on-board tests were carried out: Increase of the strength of the shoe key and shoe cam, which decreased a little the occurrence of cracks in the shoe friction material; Redesign of the shoe backing steel structure, which eliminated the occurrence of the cracks in the backing plate but could not solve completely the crack problem in the shoe friction material; Development of a new friction material, which with redesign of the shoe backing steel structure could solve satisfactorily the crack problem in the shoe friction material.

• International Journal of Computer Science & Network Security
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• 제23권9호
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• pp.8-16
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• 2023

In Japan, high-speed ground transportation service using linear motors at speeds of 500 km/h is scheduled to begin in 2027. To accommodate 5G services in trains, a subcarrier spacing frequency of 30 kHz will be used instead of the typical 15 kHz subcarrier spacing to mitigate Doppler effects in such high-speed transport. Furthermore, to increase the cell size of the 5G mobile system, multiple base station antennas will transmit identical downlink (DL) signals to form an expanded cell size along the train rails. In this situation, the forward and backward antenna signals are Doppler-shifted in opposite directions, respectively, so the receiver in the train may suffer from estimating the exact Channel Transfer Function (CTF) for demodulation. In a previously published paper, we proposed a channel estimator based on Delay and Doppler Profiler (DDP) in a 5G SISO (Single Input Single Output) environment and successfully implemented it in a signal processing simulation system. In this paper, we extend it to 2×2 MIMO (Multiple Input Multiple Output) with spatial multiplexing environment and confirm that the delay and DDP based channel estimator is also effective in 2×2 MIMO environment. Its simulation performance is compared with that of a conventional time-domain linear interpolation estimator. The simulation results show that in a 2×2 MIMO environment, the conventional channel estimator can barely achieve QPSK modulation at speeds below 100 km/h and has poor CNR performance versus SISO. The performance degradation of CNR against DDP SISO is only 6dB to 7dB. And even under severe channel conditions such as 500km/h and 8-path inverse Doppler shift environment, the error rate can be reduced by combining the error with LDPC to reduce the error rate and improve the performance in 2×2 MIMO. QPSK modulation scheme in 2×2 MIMO can be used under severe channel conditions such as 500 km/h and 8-path inverse Doppler shift environment.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제28권4D호
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• pp.533-538
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• 2008

The introduction of KTX (Korea Train Express) has brought an historic change to the overall transit system in Korea. The high-speed railway stations in particular are expanding the scope as public transit centers. However, it is evident that the evaluation on the high-speed railway stations had not been performed successfully thus far. The most important element of the evaluation is the connectivity of the departure point to the arriving stations and also the internal transfer service stations. We developed the service evaluation indicators of transfer facilities in the high-speed railway stations. The indicators are comprised of the level of service (LOS), the propriety of allocation, and the quality of information throughout the facilities in the centers. We examined the 7 stations in Korea that are currently in operation and standardized the methodology of the evaluation process by applying the indicators suggested in this study.

• Journal of the Korea institute for structural maintenance and inspection
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• 제20권4호
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• pp.94-103
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• 2016

For elevated railway station on which track is connected with superstructure of station, structural vibration level and structure-borne-noise level has exceeded the reference level due to structural characteristics which transmits vibration directly. Therefore, existing elevated railway station is in need of economical and effective vibration reduction method which enable train service without interruption. In this study, structural vibration non-transmissible system which is applied to vibroisolating material for column member is developed to reduce vibration. That system is cut covering material of the column section using water-jet method and is installed with vibroisolating material on cut section. To verify vibration reduction effect and structural performance for structural vibration non-transmissible system, impact hammer test and cyclic lateral load test are performed for 1/4 scale test specimens. It is observed that natural period which means vibration response characteristics is shifted, and damping ratio is increased about 15~30% which means that system is effective to reduce structural vibration through vibration test. Also load-displacement relation and stiffness change rate of the columns are examined, and it is shown that ductility and energy dissipation capacity is increased. From test results, it is found that vibration non-transmissible system which is applied to column member enable to maintains structural function.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제40권9호
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• pp.1699-1709
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• 2015

Moving terminals like high-speed-train undergo high Doppler frequency shift, and this leads to carrier frequency offsets that have to be compensated to avoid degradation of communication performance. In multiple access mechanism like OFDMA, base-stations need complex hardware to compensate the uplink frequency offset. In this paper, we propose a method, which can reduce burden of the base-station and makes frequency offset estimation and compensation simple. This method contains transmitting new synchronization signal, estimating frequency offsets in base-station, transmitting feedback information to terminal, and compensating the offset in uplink transmission. Simulation results show the proposed method operates well in high Doppler frequency shift conditions of 500 km/h which is the requirements of 5G mobile communication.

• Journal of the Korean Society of Hazard Mitigation
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• 제9권3호
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• pp.27-39
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• 2009

The 1st Incheon Rapid Transit Line opened in October, 1999. However, the current development plans for areas near stations do not involve plans for the both urban planning and transportation together. As the focus on only the aspect of installing a new transportation mode, the developments even make the problems such as reckless development and traffic congestion gets worse. It is required to analyse status of the current land uses and land use plans in the future and consider distribution of functions of the areas near stations and aims of development plans so as to harmonize the functions of each region in view of making balance in the whole city. The aims of developments of areas near stations has to focus on the study follows steps to find and suggest aims and strategies for the revitalization plan for areas near stations with considering the both transportation and land uses together. The plans for the areas near stations of the Incheon 1st Rapid Transit Line are analysed and then the features and rational strategies are derived. The impact is analysed as applying the development strategies derived from the step into the areas near the stations of Incheon 1st Rapid Transit line.

• International Journal of Railway
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• 제5권1호
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• pp.29-37
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• 2012

The rail sector, despite its potential for curtailing the present chaotic transport situation in Lagos, remains inefficient and underutilized. In spite of past initiatives and the current attempt by the Lagos State Government to provide a mass transit rail service in Lagos, the share of rail mode in the transport sector has not been encouraging and the railway plays an insignificant role in urban mass transit in Lagos at present. This paper sets out to assess the usage of the Lagos mass transit trains. Hence, the paper determines the passenger traffic flow along the rail route in Lagos and the number of passengers carried between 2000 and 2009 by the Lagos Mass Transit Trains (LMTT) with a view to assessing the usage of the present LMTT. This paper also discusses the historical development of Nigerian railway and describes rail transport in Lagos. Data were obtained through secondary sources coupled with review of literature. The result of this study shows that for a period of 10 years (2000-2009), Lagos mass transit trains carried a total of 9,870,101 passengers, which gives an average of 987,010 passengers annually. This suggests that the service of the Lagos mass transit train is grossly underutilized. However, LMTT contributes enormously to NRC by carrying 68.5% of the total passenger traffic of NRC between 2000 and 2009. In terms of passenger traffic flow along the route of LMTT, for a period of 1 year, Agbado station recorded the largest number of passengers (393,811), followed by Ijoko (163,652) and Iddo (120,787), while Iganmu station has the lowest number of rail commuters (16,919). This study also discloses that the major commodities hauled by Lagos district of NRC from Lagos to the northern parts of the country in 2007 are Cars, Cement, Billet and Wheat.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제16권4호
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• pp.2844-2850
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• 2015

Rolling noise caused by the contact between the train wheels and rails is the main factor of noise generated by the operation of railway, therefore the features of rail vibration and its correlations with noise radiation should be identified. In this study, noise radiation generated from vibration were predicted by utilizing FE model with boundary element method. Noise radiation generated from vibration were predicted by utilizing FE model with boundary element method, and were compared with the measured noise in order to validate the reliability of the analysis method. In addition, the features of noise radiation according to the rail attenuation were examined in the frequency domain, and the noise radiation has been reduced by approximately 3dB(A) with additional rail damping.

• Asian Journal of Atmospheric Environment
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• 제7권1호
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• pp.38-47
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• 2013

$PM_{10}$ concentrations were measured at four monitoring sites at the Daechaung station of the Seoul subway. The four locations included two tunnels, a platform, and a waiting room. The outside site of the subway was also monitored for comparison purposes. In addition, the effect of the platform screen doors (PSDs) recently installed to isolate the $PM_{10}$ in a platform from a tunnel were evaluated, and a comparison between $PM_{10}$ levels during rush and non-rush hours was performed. It was observed that $PM_{10}$ levels in the tunnels were generally higher than those in the other locations. This might be associated with the generation of $PM_{10}$ within the tunnel due to the train braking and wear of the subway lines with the motion of the trains, which promotes the mixing and suspension of particulate matter. During this tunnel study, it was observed that the particle size of $PM_{10}$ ranged from 1.8 to 5.6 ${\mu}m$. It was revealed that the $PM_{10}$ levels in the tunnels were significantly increased by the PSDs, while those in the platform and waiting room decreased. As a result, in order to estimate the effect of ventilation system on $PM_{10}$ levels in the tunnels, fans with inverters were operated. It was found that the concentration of $PM_{10}$ was below 150 ${\mu}g/m^3$ when the air flow rate into a tunnel was approximately 210,000-216,000 CMH.