• Journal of the Korean association of regional geographers
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• v.10 no.2
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• pp.252-266
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• 2004

This study analyzes the influence of the construction of a high-speed railroad on territorial organization in France. After development of a new transportation network, the French territorial organization has been largely modified. Many economic urban areas are modified by their position in the territorial hierarchy according to their condition of connection with the TGV network. At first, spatial convergence is the most important effect of the TGV network construction. Second, the development of a transportation network concentrated in the Paris area has influence as an intensified factor on metropolitan areas and as a weakening factor on middle- and small-sized cities. Thus, this system has risk in increasing territorial imbalance in France. Third, to implant an economic activity zone around new TGV stations, a new town or a new economic center starts to develop. This is going to grow into a second core outside of the old city center so that regional spatial organization is transformed from a mono-polarized(mono-centric) organization to a multi-polarized(polycentric) one. Lastly, the integration of the EU railroad system enhances the concentration of economic activity in European metropolitan areas as each metropolitan area tries to develop more competitive space for its rising position in the global urban hierarchical system.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.447-453
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• 2012

It is studied that the structure of the contact plane geometry of the contact wire would be changed when the contact wire tension is increased in the existing overhead contact lines for the purpose of improving the operation speed temporarily. In this paper, the dropper length formula which could be well applied to the pre-sagged catenary is reviewed first. Second, the changing amount of the pre-sag if the contact wire tension change from 20kN to 23kN or from 20kN to 25kN for the Gyeongbu HSL(high speed line) 49.5m catenary is evaluated by using of the self-written program in accordance with the dropper length formula. Moreover, the increasing tension and measuring the pre-sag change experiment in the Gyeongbu 2 HSL was conducted. The calculated data are compared with the measured data. As a result, it is found that the geometry change is very little and will not make the current collection performance deteriorated.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.3
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• pp.116-130
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• 2023

Expressways play pivotal roles in cargo transportation because of their superior accessibility and mobility compared to rail and air. On the other hand, there is a limit to the accurate calculation of cargo transportation performance using existing highways owing to the mixture of vehicle types and difficulty in identifying cargo loads of individual cargo vehicles. This paper presents an algorithm for calculating more reliable cargo transportation performance using big data. The traffic performance (veh·km/day) was derived using the data collected from Toll Collecting System. The average tolerance weight for each vehicle type and the cargo load unit (ton/unit) considering it was calculated using vehicle specification information data and high-speed and low-speed axis data. This study calculated the cargo transportation performance by section and type using various online integrated highway data and presented a method for calculating the transportation performance by linking open business offices and private highways.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.435-444
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• 2017

The vehicle-track structure dynamic interaction analysis problem can be treated as sliding contact problem, and it is assumed that vehicle run at a constant speed over a rail modeled as beam elements. Unfortunately, Salome-Meca can not satisfy the compatibility condition for the beam master elements, which are consist of the elements with higher order polynomial shape function, in sliding contact problem. In this study, it is suggested to use more finer beam master element mesh as the remedy for incompatibility in sliding contact problem, and the accuracy of the solution is secured. For this, the effect of beam element mesh refinement consisting runway is analysed through simple examples, and the applicability to the dynamic interaction analysis is evaluated. Finally, the dynamic interaction analysis of railway skewed culvert transition problem is carried out to evaluate the effect of supporting stiffness due to backfill pattern changes and track irregularity due to uneven subgrade settlement.

• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.109-116
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• 2016

The market share of high-speed railway vehicles is increasing across the world. A high-performance impact energy absorption factor is essential to satisfy the safety standards of railway vehicles. A deformed tube assembly is a typical energy absorption factor in railway vehicles. The tube assembly comprises a deformed tube and a press-fitting punch, its performance depends on the absorption energy characteristics in the plastic zone of the tube. In this study, a deformed tube assembly of a railway vehicle is designed that can absorb a maximum impact energy of 200kJ under plastic deformation. Slab method and finite element analysis are used to estimate the reaction force of the punch in the initial stage, the performance of the designed tube assembly is confirmed experimentally.

• Smart Structures and Systems
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• v.32 no.4
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• pp.267-279
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• 2023

Data modelling and interpretation for structural health monitoring (SHM) field data are critical for evaluating structural performance and quantifying the vulnerability of infrastructure systems. In order to improve the data modelling accuracy, and extend the application range from data regression analysis to out-of-sample forecasting analysis, an improved most likely heteroscedastic Gaussian process (iMLHGP) methodology is proposed in this study by the incorporation of the outof-sample forecasting algorithm. The proposed iMLHGP method overcomes this limitation of constant variance of Gaussian process (GP), and can be used for estimating non-stationary typhoon-induced response statistics with high volatility. The first attempt at performing data regression and forecasting analysis on structural responses using the proposed iMLHGP method has been presented by applying it to real-world filed SHM data from an instrumented cable-stay bridge during typhoon events. Uncertainty quantification and correlation analysis were also carried out to investigate the influence of typhoons on bridge strain data. Results show that the iMLHGP method has high accuracy in both regression and out-of-sample forecasting. The iMLHGP framework takes both data heteroscedasticity and accurate analytical processing of noise variance (replace with a point estimation on the most likely value) into account to avoid the intensive computational effort. According to uncertainty quantification and correlation analysis results, the uncertainties of strain measurements are affected by both traffic and wind speed. The overall change of bridge strain is affected by temperature, and the local fluctuation is greatly affected by wind speed in typhoon conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.911-917
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• 2015

The objective of this work focuses on the analysis of injection rate and macroscopic spray behavior characteristics with injection pressures as well as combustion and exhaust emission characteristics with injection timing and injection pressure by using a common rail single-cylinder diesel engine. The injection rate was measured by applying the Bosch method, and macroscopic spray behavior characteristics were analyzed with a constant-volume vessel and a high-speed camera. In addition, combustion and emission characteristics were analyzed in a common-rail single-cylinder diesel engine with precise control of fuel injection timing and pressure. For injection pressures of 30MPa and 50MPa, the injection rate was higher at 50 MPa, and the spray development (penetration) was also higher in the same elapsed time. The peak in-cylinder pressure and rate of heat release showed a tendency to decline as injection timing was delayed, and the peak in-cylinder pressure and rate of heat release were slightly higher for higher injection pressures. Higher injection pressures also reduced the mean effective pressure, while the indicated mean effective pressure and torque increased as injection timing was delayed to TDC. Nitrogen oxides had a peak level at injection timings of $BTDC20^{\circ}$(30MPa) and $BTDC15^{\circ}$(50MPa); carbon monoxide emissions were reduced by delaying injection timing from $BTDC30^{\circ}$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7176-7181
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• 2015

This thesis is about the system where the solar module is attached to the high functional guardrail posts with anti-weed, anti-plant, and road-kill applied to produce internal power, enabling the integrated control and real-time monitoring of appearance of wildlife and road conditions using the USN. The whole system consists of a photovoltaic module(PV), a detection sensor(pyroelectric), a controller(operation select and motion sensor), the USN system, the DB(sound and flash), an output unit of sound and flash, and the control system of road-kill prevention and safety induction for vehicles. Thus this study aims to address the remote control and monitoring system of multipurpose guardrails to improve road environment, prevent road-kills, protect wild animals, and guide cars safely by using the USN which is combined with new renewable energy and IT convergence technology. As a result of the study on the remote control and monitoring system using the USN, it was ascertained that the response time of the unmanned sensing system was within 5.1 ms with the current consumption of 0.328 mA, and the data transmission speed of the remote control system was 250 kbps with the current consumption of 0.283 mA.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.532-542
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• 2018

Because maglev trains have a propulsion and absorption force without contact with the rails, they can drive safely at high-speed with little oscillation. Recently, test model of a maglev propulsion train was produced and operated, and has since been chosen as a national growth industry in South Korea; there have been many studies and considerable investment in these fields. This study examined the dynamic responses due to bridge-maglev train interaction and basic material to design bridges for maglev trains travelling at high-speed. Depending on the major factors affecting the dynamic effects, the scope of this study was restricted to the relationship between dynamic responses. A concrete box girder was chosen as a bridge model and injured train and rail types in domestic production were selected as the moving train load and guideway analysis model, respectively. From the analysis results, the natural frequency of a bridge for a maglev train, which has a deflection limit L/2000, was higher than those of bridges for general trains. The dynamic responses of the girder of the bridge for a maglev train showed a substantial increase in proportion to the velocities of the moving train like other general bridge cases. Maximum dynamic response of the girder is shown at a moving velocity of 240km/h and increased with increasing moving velocity of train. These results can be used to design a bridge for maglev propulsion trains and provide the basic data to confirm the validity and verification of the design code.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.128-139
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• 2017

Railway is one of the public transportation systems along with shipping and aviation. With the recent introduction of high speed train, its proportion is increasing rapidly, which results in the higher risk of catastrophic failures. The wheel bearing to support the train is one of the important components requiring higher reliability and safety in this aspect. Recently, many studies have been made under the name of prognostics and health management (PHM), for the purpose of fault diagnosis and failure prognosis of the bearing under operation. Among them, the most important step is to extract a feature that represents the fault status properly and is useful for accurate remaining life prediction. However, the conventional features have shown some limitations that make them less useful since they fluctuate over time even after the signal de-noising or do not show a distinct pattern of degradation which lack the monotonic trend over the cycles. In this study, a new method for feature extraction is proposed based on the observation of relative frequency energy shifting over the cycles, which is then converted into the feature using the information entropy. In order to demonstrate the method, traditional and new features are generated and compared using the bearing data named FEMTO which was provided by the FEMTO-ST institute for IEEE 2012 PHM Data Challenge competition.