• Journal of the Korean Society for Railway
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• v.7 no.1
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• pp.20-25
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• 2004

Railroad geotechnical information management system was developed by using Web GIS and DB in this study. The standardization of railroad geotechnical information is progressed by classifying three groups as like basic informations, vibration informations along railway lines and design drawings. The basic informations consisted of basic and dynamic properties of soils, geophysical exploration and seismic survey/exploration. And the specification for 'human exposure to whole-body vibration' was adopted to construct the vibration informations along railway lines. The informations as like drawings and photographs were saved by changing to graphic files in the standardization of design drawings. In the case of standardization of geographical information, the topographical maps(NGIS, 1:5000) were primarily used as digital maps. Another digital maps(KRRI, 1:5000) and their geographical DB based on NGI code system were added on this maps. The standardized informations were used to construct their database. And railroad information management system was developed using Entity-Relation(ER) model which had a good feasibility for expansion and transition to other system in designing stage of database. This system consisted of layer selection, search and analysis of geotechnical informations and Zeus DB was adopted for GIS operating and user interface. This system could be a good tool for saving, searching and analyzing the geotechnical and geophysical informations. These DB systems would offered the basic informations to plans, design and construction of railroad lines etc. in practical use.

• International Journal of Railway
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• v.7 no.3
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• pp.85-89
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• 2014

The use of pozzolanic materials in concrete mixtures can enhance the mechanical properties and durability of concrete. By reactions with pozzolanic materials and calcium hydroxide in cement matrix, calcium-silicate-hydrate (C-S-H) increases and calcium hydroxide decreases in cement matrix of concrete. Consequently, the volume of solid materials increases. The pozzolanic particles also fill spaces between clinker grains, thereby resulting in a denser cement matrix and interfacial transition zone between cement matrix and aggregates; this lowers the permeability and increases the compressive strength of concrete. Moreover, the total contents of alkali in concrete are reduced by replacing cements with pozzolanic materials; this prevents cracks due to alkali-aggregate reaction (AAR). In this study, nanosilica is incorporated in cement pastes. The differences of microstructural compositions between the hydrated cements with and without nanosilica are examined using nanoindentation, XRDA and $^{29}Si$ MAS NMR. The results can be used for a basic research to enhance durability of concrete slab tracks and concrete railway sleepers.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.344-353
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• 2015

Recently, the utilization of the BIM system has been extended to cost and resource simulation, visualized management of construction site information and application of augmented reality including basic 3D modeling. Therefore, various BIM functions are being developed for practical applications. However, since clear classification criteria and knowledge information of BIM functions are not sufficient for field engineers, it is difficult to identify the necessary BIM functions for a construction project. This study suggests a BIM function breakdown structure considering the individual functional properties and a process model that can be ordered by applying BIM in a railway construction project. The proposed delivery model is used to obtain a practical utilization of BIM by analyzing features applicable to railway construction projects; model is verified using a case project.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.132-138
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• 2003

The use of long rails in high-speed railway bridges causes additional stresses due to nonlinear behaviours between the rail and bridge decks in the neighbourhood of the deck joints. In the seismic response analysis of high-speed railway bridges, since structural response is highly sensitive to properties of the ground motion, spatial variation of the ground excitation affects responses of the bridges, which in turn affect stresses in the rails. In addition, it is shown that high-speed trains need very long distances to stop when braking under seismic occurrence corresponding to operational earthquake performance level so that verification of the safe stoppage of the train is also required. In view of such additional stresses due to long rails, sensibility of structural response to the properties of the ground motion and braking distance needed by the train to stop safely, this paper proposes and establishes a time domain nonlinear dynamic analysis method that accounts for braking loads, spatial variation of the ground motion and material nonlinearities of rails to analyze long rail stresses in high-speed railway bridges subjected to seismic event. The accuracy of the proposed method is demonstrated through an application on a typical site of the Korean high-speed railway.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.391-396
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• 2005

Salt water spray test and salt water immersion test were experimentally conducted in order to investigate the durability of fiber reinforced composites under salt water environment. The specimens were made of glass fabric reinforcement and phenolic resin. Mechanical test was performed to obtain mechanical properties such as tensile properties, flexural properties, and shear properties by varying with exposure times. Also dynamic mechanical test and FTIR were conducted to investigate a change in chemical structure as well as thermal analysis properties such as storage shear modulus, loss shear moduls, and tan ${\delta}$. According to the results, salt water environment has effected on mechanical properties and thermal analysis properties and especially the durability of glass fabric/phenolic composites were severely affected on salt water immersion environment rather than salt water spray environment.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.410-417
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• 2000

The strength properties of Light-Weighted Soils(LWS) mixed with Expanded Polystrene(E.P.S.) using uniaxial and triaxial tests are studied. Test results show that when the initial water contents of dredged soils are under 135% and the cement contents are above 1%, Light-Weight Soils are in the appropriate strength range of 2.0 lo 4.0kg/$\textrm{cm}^2$. However. E.P.S. contents had a little effects on the strength properties of LWS.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.510-515
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• 2004

In this study, we investigate the mechanical properties of rail pad material according to pad types. Especially, to study the application and endurance of TEEE material, we conducted experiments such as tension strength test, hardness test, fatigue test and wear test. Test results showed that TEEE material was better application and endurance than other pad material, but there was difficulties for comparing with others because the variations of application according to pad' types were variable.

• Journal of the Korean Society for Railway
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• v.13 no.4
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• pp.404-411
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• 2010

Authors conducted a deduction and characteristic calculation of the some parameters using a magnetic equivalent circuit method to verify a basic design result of a rotary-typed small-scaled linear induction motor for a railway transit. In a LIM, it is possible to express the parameters of the magnetic equivalent circuit into a function of the shape of the secondary aluminium plate and the airgap between the LIM primary core and the secondary aluminium plate. It means that the LIM properties can be changed considerably by the shape of the secondary aluminium plate and the airgap between the LIM primary core and the secondary aluminium plate. So, authors analyzed a tendency of changes of the magnetic equivalent circuit parameters and the LIM characteristics by changing of the airgap, the thickness of the secondary aluminium plate and the overhang length and shape of a rotary-typed small-scaled LIM, and accomplished a basic research to develop a real-scaled LIM for a railway transit.

• Journal of the Korean Geosynthetics Society
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• v.11 no.1
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• pp.23-33
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• 2012

The stability of urban railway foundation can be a problem due to the excessive settlement. The settlement at the base of railway is monitored by the installed settlement gauges. The piezometer and pore water pressure measurement device are installed to measure the variation of pore water pressure and ground water table during the continuous pullout of sheet piles which were used for the braced cut. The settlement of railway is predicted with using the computer program CAIN RDA. The input data for the numerical analysis are obtained from the field soil exploration data and soil properties. The surcharged load from landscaping over the ground surface and the weight of train are taken into account for the estimation of settlement. As a result of numerical analysis, the range of settlement for six different Sites is from 5.94 cm to 12.77 cm. Thus, the settlement level at Site 2 is occurred 12.77 cm which is higher than the allowable settlement of 10 cm.

• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.417-426
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• 2016

In this study, the optimal welding condition of an extruded AZ61 magnesium alloy plate was investigated through evaluation of the mechanical properties and microstructure in the friction stir welding zones. The friction stir welding conditions considered in this study were the tool rotation speeds of 400, 600, and 800rpm and the welding speeds of 200, 300, and 400mm/min. To evaluate the welding strength, tensile and hardness tests were carried out. Microstructures of the welded regions were examined using optical microscopes. Under a tool rotation speed of 800rpm and welding speed of 200mm/min, the joint showed the best joining properties. The UTS, yield strength, and elongation of the welded region showed values of 79.0%, 65.4%, and 30.1%, respectively, of those of the base metal.