• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.223-231
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• 2015

This paper proposes a new wireless backhaul technology based on MHN(Mobile Hotspot Network) which uses a wide frequency band of millimeter wave to provide wideband Wi-Fi services for subway passengers. Performance analysis of MHN up and down links, based on data: up and down links structure analysis of physical layer and simulation study of the MHN wireless backhaul link model, show that the proposed MHN-based wireless backhaul network can transmit data at a 1.2Gbps data rate and provide Internet service 100 times faster than that of conventional WiBro-based wireless backhaul networks. These results indicate that the proposed MHN technology is appropriate for subway mobile networks.

• Wind and Structures
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• v.36 no.6
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• pp.423-434
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• 2023

Aerodynamic force coefficients are generally obtained from traditional wind tunnel tests or computational fluid dynamics (CFD). Unfortunately, the techniques mentioned above can sometimes be cumbersome because of the cost involved, such as the computational cost and the use of heavy equipment, to name only two examples. This study proposed to build a deep neural network model to predict the aerodynamic force coefficients based on data collected from CFD simulations to overcome these drawbacks. Therefore, a series of CFD simulations were conducted using different geometric parameters to obtain the aerodynamic force coefficients, validated with wind tunnel tests. The results obtained from CFD simulations were used to create a dataset to train a multilayer perceptron artificial neural network (ANN) model. The models were obtained using three optimization algorithms: scaled conjugate gradient (SCG), Bayesian regularization (BR), and Levenberg-Marquardt algorithms (LM). Furthermore, the performance of each neural network was verified using two performance metrics, including the mean square error and the R-squared coefficient of determination. Finally, the ANN model proved to be highly accurate in predicting the force coefficients of similar bridge sections, thus circumventing the computational burden associated with CFD simulation and the cost of traditional wind tunnel tests.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1948-1953
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• 2007

Intelligent agent is to decide what customers need on the internet and offer them accurate information. In this paper, the system which can recommend the tourism items in terms of customer's needs is proposed by appling the intelligent agent to railway tourism system. Most of previous agents are focused on price. But, this study proposes the Railway tourism system which offers each customer the best suitable information based on quality of information and reputation. The customer's needs are analyzed through intelligent agent and the information which is suitable for customer's needs is obtained the Artificial Neural Network Model.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1402-1404
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• 2000

The electrified railway has various power supply schemes. Although the identical trains are operated in same condition and the impedance of track are equal, the genealogy impedance of track is changed according to composition method of feeding scheme. So, the harmonic current flowing into the railway substation are greatly unlike. For simulation of harmonic magnification flowing into the railway substation according to feeding scheme, we propose 6-port network analysis method based on 4-port network, find 6-port equivalent model of each circuit component, and compare and investigate harmonic magnification in the case of parallel post and normal feeding scheme.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.535-542
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• 2002

This paper show communication network scheme problem for the railway is solved which were electrical noise and line break in wayside using rerouting communication line, Considering the availability and the maintainability based on the reliability in design of communication networks. At first, Self-Healing Ring algorithm is suggested in that solution which is satisfied with above requirements. And also, in the advanced type, Dual Master scheme is suggested that the problem which is occurred in line break of both main and sub line at the same time can be solved using DMSHR(Dual Master Self Healing Ring). Therefore total reliability in railway system is going to be advanced using DMSHR scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.893-895
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• 2014

Railway dedicated frequency bandwidth allocation matters are being discussed actively before an introduce of wireless communication based train control system to korean railway industry. Allocating the frequency band, which has great value as a public resource, for suitable use with right amount is particularly important, because of equity in other fields and valuable use of limited resources. In this paper, the feasibility about stable railway communication network operation based on LTE in diverse frequency bandwidth will be discussed with solicitous simulation.

• Journal of the Korean Society of Safety
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• v.26 no.6
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• pp.111-117
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• 2011

Risk-based railway safety management has been mandatory in Korea as by relevant laws and regulations enacted since the Railway Safety Act 2004. In particular, the Railway Vehicle Safety Guidance came into effect on Jan 1, 2008 specifies the details of methodology for hazard analysis, risk assessment and safety verification and validation. Fundamentals for success of the risk-based safety management are systematic hazard identification and risk assessment by use of reasonable risk assessment criteria, but the principle of risk-based safety management has not been applied in an effective way to introduction and maintenance of railway vehicle systems because definite risk assessment criteria have not been set down for each railway system or railway network. The purpose of this study is to suggest a risk matrix development principle for risk assessment of domestic urban metro vehicles by analyses of relevant rules and railway operating environment of Korea.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.114-119
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• 2008

A refined three-dimensional finite element interaction model between the high-speed train and railway bride deck has been developed in the present study. Analytical predictions of vertical deflections for a railway bridge are compared with in-situ test results and a good agreement is achieved. Then, input variables employed in the analytical comparisons are selected as random variables for the limit state functions. followed by risk assessment. For this purpose, a linear adaptive weighted response surface method has been developed and applied. A typical railway bridge has been selected and the limit state functions are employed from UIC and Korean specifications in the comparative studies. The results reveal that Korean specifications give significantly risky reliability indices in comparison with UIC specifications. It is thus encouraged from the above that the present linear adaptive weighted response surface method can be an alternative for the fast estimation of nonlinear structural systems.

• Journal of the Korean Geotechnical Society
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• v.36 no.3
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• pp.5-14
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• 2020

The railway concrete track has been increasingly adopted for high-speed train such as KTX due to its high running stability, improved ride quality for the passengers, and low maintenance cost. However, excessive settlement of the railway concrete track has been monitored at embankment sections of the ◯◯ High-speed Line, resulting in the concerns on the safety of railway operation. In order to establish an effective maintenance plan for the concrete track railway exceeding the allowable residual settlement, it is essential to reasonably predict their long-term settlement behavior during the public period. In this study, we developed a model for predicting the long-term settlement behavior of concrete track using recurrent neural network (RNN) and examined the applicability of the developed model.

• Journal of Korea Technology Innovation Society
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• v.3 no.3
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• pp.1-17
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• 2000

This paper shows the institutional limits of technological innovation at the railway package service, that is the limits of introducing the package express system. The railway package service, owned by government and operated by D company, has been suffered severe operating loss since early 1990's. The package express system supported by information network and co-working with inner city quick service might be an solution for the railway package service. But there are several obstacles such as labor union and the rigidities of the Korean National Railroad of government agency.