• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1821-1829
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• 2017

A point machine requires lots of time and attention in terms of maintenance, since it causes 40% of failures among the railway signaling devices. The senescence of the point machine critically matters to the overall turnout system. In this paper, we analyzed the aging characteristics of the point machine by using the switching current of the point machine. The analysis is done based on the switching current measurements of the point machines deployed in the Sehwa outdoor test site and the Korail Kyongbu line. It is expected that the analysis result can be utilized for real-time diagnosis in the aspect of the maintenance of the point machines and predicting abnormal operations.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.23-29
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• 2008

Most VE operation related to construction project is progressed in stage of planing or design phase, especially in case of domestic. It is encouraging fact and if you have VE process in stage of planning and design, you'll have experience a reduction of about 70% of total saving cost in which total construction process may occurred. However, recently the work of construction in overseas increase and almost is only construction-work, except planning and design process. As this reason, VE process for construction-work phase only is demanded in high necessity. VE in construction phase comes to accomplish intensively in the part which the design change does not follow, through know-how, equipment operating method and method of temporary-structure erection at the established construction-site learned, builders will be the possibility of reduction from 3% to 10% in constructive expense. This paper describes VE performing example in OO company's construction-work phase, and propose the methodology of VE performance in the phase of construction. And also it is aimed to extending VE applications into the overseas construction enterprise.

• Earthquakes and Structures
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• v.13 no.2
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• pp.193-200
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• 2017

To overcome the difficulty of performing multi-point response spectrum analysis for engineering structures under spatially varying ground motions (SVGM) using the general finite element code such as ANSYS, an approach has been developed by improving the modelling of the input ground motions in the spectral analysis. Based on the stochastic vibration analyses, the cross-power spectral density (c-PSD) matrix is adopted to model the stationary SVGM. The design response spectra are converted into the corresponding PSD model with appropriate coherency functions and apparent wave velocities. Then elements of c-PSD matrix are summarized in the row and the PSD matrix is transformed into the response spectra for a general spectral analysis. A long-span high-pier bridge under multiple support excitations is analyzed using the proposed approach considering the incoherence, wave-passage and site-response effects. The proposed approach is deemed to be an efficient numerical method that can be used for seismic analysis of large engineering structures under SVGM.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.6
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• pp.879-885
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• 2022

Of increasing global popularity is the multi-dimensional use and development of cities to address land use and urban issues caused by high urban density and challenging topography. In Korea, the city of Busan has a large proportion of mountainous areas, and the Gyeongbu Line that runs through the city's center has been interrupting this urban area for over 117 years. Because a lack of usable land is hindering the development of the city, introducing a multi-dimensional approach to urban development is seen as important. Accordingly, the Gyeongbu Line underground project is attempting to solve the problem of disconnection of Busan's city center and increase the amount of usable land for varied multi-dimensional use. In this study, by conducting a preference survey among those who live near the underground project sites of the Gyeongbu Line stations in Busan, the planned use of each available land arearesulting from the multi-dimensional development of railroadsand railway stations was investigated. However, in order to further the results of the survey, legal and institutional support is needed. There are limits to the multi-dimensional use of land, such as the lack of interconnection between individual laws and the lack of specific guidelines for multi-dimensional development.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.836-842
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• 2011

The lateral stability of bridge foundations against train moving load, emergency stopping load, earthquakes, and so on is very important for a railway bridge foundation. A borehole test is much more accurate than laboratory tests since it is possible to minimize the disturbance of ground conditions on the test site. The representative borehole test methods are Dilatometer, Pressuremeter and Lateral Load Tester, which usually provide force-resistance characteristics in elastic range. In order to estimate P-y curves using those methods, the non-linear characteristics of soil which is one of the most important characteristics of the soil cannot be obtained. Therefore, P-y curves are estimated usually using elastic modulus ($E_O$, $E_R$) of lateral pressure-deformation ratio obtained within the range of elastic behavior. Even though the pile foundation is designed using borehole tests in field to increase design accuracy, it is necessary to use a higher safety factor to improve the reliability of the design. A Large Displacement Borehole Testmeter(LDBT) is developed to measure nonlinear characteristics of the soil in this study. P-y curves can be directly achieved from the developed equipment. Comparisons between measured P-y curves the LDBT developed equipment, theoretical methods based on geotechnical investigations, and back-calculated P-y curves from field tests are shown in this paper. The research result shows that the measured P-y curves using LDBT can be properly matched with back-calculated P-y curves from filed tests by applying scale effects for sand and clay, respectively.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.214-221
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• 2010

The transitional zone between tunnel and earthwork is one of the most vulnerable areas site for railway lines and because of differential settlement due to different stiffness of each supporting layer, it has to conducted a maintenance work constantly. In this study, it is conducted to compare the effect of reinforcement by wheel load and displacement of the sleepers after existing sleepers are replaced with the large sleepers for 20m long in-field transitional zone. Also, numerical parametric study using multi-layer elastic method has been performed to compare rail force, settlement and stresses of ballast while varying size and space of the sleeper. The field test and numerical results show that replacing the large sleepers improves about 10% of total settlement and coefficient of wheel force than conventional sleepers. Effectiveness of improvement is about 9.3%, 4%, 14.5% for rail seat force, settlement of sleepers and ballast pressure respectively with size of sleepers.

• Smart Structures and Systems
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• v.21 no.5
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• pp.591-600
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• 2018

The probabilistic characterization of wind field characteristics is a significant task for fatigue reliability assessment of long-span railway bridges in wind-prone regions. In consideration of the effect of wind direction, the stochastic properties of wind field should be represented by a bivariate statistical model of wind speed and direction. This paper presents the construction of the bivariate model of wind speed and direction at the site of a railway arch bridge by use of the long-term structural health monitoring (SHM) data. The wind characteristics are derived by analyzing the real-time wind monitoring data, such as the mean wind speed and direction, turbulence intensity, turbulence integral scale, and power spectral density. A sequential quadratic programming (SQP) algorithm-based finite mixture modeling method is proposed to formulate the joint distribution model of wind speed and direction. For the probability density function (PDF) of wind speed, a double-parameter Weibull distribution function is utilized, and a von Mises distribution function is applied to represent the PDF of wind direction. The SQP algorithm with multi-start points is used to estimate the parameters in the bivariate model, namely Weibull-von Mises mixture model. One-year wind monitoring data are selected to validate the effectiveness of the proposed modeling method. The optimal model is jointly evaluated by the Bayesian information criterion (BIC) and coefficient of determination, $R^2$. The obtained results indicate that the proposed SQP algorithm-based finite mixture modeling method can effectively establish the bivariate model of wind speed and direction. The established bivariate model of wind speed and direction will facilitate the wind-induced fatigue reliability assessment of long-span bridges.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.788-792
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• 2009

Railroad is well known for eco-friendly transportation system. But, for past few decades, there might be happened many contamination acts in railway facility sites. Industrial and municipal solid wastes produced to maintain and fix trains were dumped to underground of railroad depot area. To develop and reconstruct this area, we should remediate the contaminated soil and ground water. This study was conducted to evaluate the soil pollution status of railroad depot and propose the optimum remediation processes. Our investigation showed that main pollutants sources were TPH and some heavy metals from the dump site. The surveying results for the soil under rail track and crossing nose areas showed TPH contamination from crossing nose area causing lubricant agent. It could be use and rehabilitate the railroad facility areas to an intended purpose with an application of well designed in-situ and ex-situ remediation processes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.601-608
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• 2021

Recently, despite a decrease in the number of working days and an increase in the number of non-working days due to an increase in the abnormal climate and the revision of the Labor Standards Act, a standard construction period reflecting this has not been established. For this reason, even if the appropriate construction period is calculated at the site, there is a situation where delays occur due to unexpected circumstances. Therefore, this study proposes a method of calculating the number of non-working days for railway bridgework construction that reflects changes in construction conditions and climate change and reflects this to railway bridgework construction, and the number of working days was calculated. As a result, the number of non-working days by region and month in Korea was derived, and through this, the necessity of regulations and standards for appropriate construction periods reflecting regional characteristics and characteristics of each construction type was presented.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.411-416
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• 2018

It is generally not preferable to install a turnout on a sharp curves but it is not desirable for the safety of a train. However, in a mountainous area or a depot where a sufficient space can not be secured to secure a straight line. In this study, in order to analyze the cause of train derailment accident that occurred in the place where turnout is installed in a sharp curves, we performed derailment analysis using line data and accident vehicle data measured at the location where the accident occurred. This derailment coefficient maximum turnout at the start of the track and derailment curve analysis showed that even big enough to cause a derailment as 1.37 in size, which was found to be consistent with the actual site survey results derailment occurred.