• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.202-206
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• 2013

A submerged floating railway is an innovative tunnel infrastructure passing through the deep sea independent of wave and wind so that high speed trains can run on it. It doesn't depend on water depth and is cost effective due to modular construction on land. The construction period can be reduced drastically. This paper introduces the concept design of a submerged floating railway, and for securing safety, proposes a method to analyze the structural behavior of the body in case of collision with a submarine. The theory of a beam with an elastic foundation was used to calculate the equivalent mass of the body so that the perfect elastic collision could be applied to calculate the collision velocity. The maximum deformation and bending moment was analyzed based on energy conservation. To verify the results, a collision analysis using a finite element analysis code was made. Comparing the results confirmed that this simplified collision analysis method gives enough accurate deformation and bending moment to be used for actual estimation in the initial design stage.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.175-181
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• 2014

This paper suggests O(m) polynomial time heuristic algorithm to obtain the solution for the driver scheduling problem, DSP, that has been classified as NP-complete problem. The proposed algorithm gets the initial assignment of n minimum number of drivers from given m schedules. Nextly, this algorithm gets the minimum total time (TC) using 5 rules of swap and insert for decrease of over times (OT) and idle times (IT). Although this algorithm is a heuristic polynomial time algorithm with O(m) time complexity rules to be find a optimal (or approximate) solution, this algorithm is equal to metaheuristic methods for the 5 experimental data. To conclude, this paper shows the DSP is not NP-complete problem but Polynomial time (P)-problem with polynomial time rules.

• Korean Journal of Remote Sensing
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• v.34 no.6_1
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• pp.1131-1142
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• 2018

The autonomous vehicles are being developed and operated widely because of the advantages of reducing the traffic accident and saving time and cost for driving. The vehicle localization is an essential component for autonomous vehicle operation. In this paper, localization algorithm based on sensor fusion is developed for cost-effective localization using in-vehicle sensors, GNSS, an image sensor and reference images that made in advance. Information of the reference images can overcome the limitation of the low positioning accuracy that occurs when only the sensor information is used. And it also can acquire estimated result of stable position even if the car is located in the satellite signal blockage area. The particle filter is used for sensor fusion that can reflect various probability density distributions of individual sensors. For evaluating the performance of the algorithm, a data acquisition system was built and the driving data and the reference image data were acquired. Finally, we can verify that the vehicle positioning can be performed with an accuracy of about 0.7 m when the route image and the reference image information are integrated with the route path having a relatively large error by the satellite sensor.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.217-228
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• 2021

After the integrated fare system has been applied, public transportation and transfer traffic increased. As a result, transfer passengers must be considered in the operation of the bus. Although previous studies have limitations due to utilizing deterministic mathematical models, which fails to reflect the stochastic movements of passengers and buses, in this study, a more realistic bus stop micro-simulation model is proposed. Based on the proposed simulation model, we represent the relationship between bus arrival interval and passenger wait time as a regression model and empirically show the differences between the cases with and without transfer passengers. Also, we propose a method converting passenger waiting time to cost and find optimal bus arrival interval based on the converted cost. It is expected the proposed method enables bottom-up decision making reflecting practical situation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.6
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• pp.837-842
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• 2022

The "Intelligent Railroad Alignment Design Program (ei-Rail) developed in 2013 has been adopted in the planning and the evaluation/validation of design results of oversea railroad construction projects. Target countries of Korean railroad industries requires the operating speed increase with alignment improvement and the double tracking of prevailing single track railroads as well as new railroad construction. This study is to develop an additional module for double tracking project of prevailing single track railroads in the ei-Rail. The developed method is based on the geometrics of prevailing railroad, and the definition of planned project determines the project cost based on the unit cost by work type, and provides the draft design of double track. The module was validated with a oversea case. It is then expected for oversea railroad double tracking project more efficiently in planning and the evaluation of design results.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.133-146
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• 2023

Traffic states in urban areas are essential to implement effective traffic operation and traffic control. However, installing traffic sensors on numerous road sections is extremely expensive. Accordingly, estimating the traffic state using a vehicle-mounted camera, which shows a high penetration rate, is a more effective solution. However, the previously proposed methodology using object tracking or optical flow has a high computational cost and requires consecutive frames to obtain traffic states. Accordingly, we propose a method to detect vehicles and lanes by object detection networks and set the region between lanes as a region of interest to estimate the traffic density of the corresponding area. The proposed method only uses less computationally expensive object detection models and can estimate traffic states from sampled frames rather than consecutive frames. In addition, the traffic density estimation accuracy was over 90% on the black box videos collected from two buses having different characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1741-1746
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• 2022

As the use of school buses becomes more common, related laws are being enacted, such as making it mandatory for children to check school bus dropouts due to frequent accidents caused by the negligence of school bus drivers and their guardians. In this paper, we propose a safe school bus system that links efficient radio-frequency identification (RFID) and mobile APP in terms of energy utilization and cost. The school bus system uses RFID cards to check information on children boarding the school bus, and real-time SMS transmission allows parents to safely send their children to and from school. Instructors on the school bus can check their children's disembarkation information once more through APP, preventing various accidents that may occur to children left on the bus. Due to the automation of the school bus operation log, daycare center teachers can not only check the information on getting on and off, but also manage the information on the attendance and discharge of the students.

• Journal of the Korean Geotechnical Society
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• v.39 no.11
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• pp.23-31
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• 2023

The escalating settlements observed in concrete slab tracks pose a significant challenge in Korea, raising concerns about their adverse impact on the safe operation of high-speed railways and the substantial costs involved in restoration. A primary contributor to these settlements is identified as the utilization of rock materials sourced from tunnel construction, incorporated into the lower subgrade without the requisite soil mixing to achieve an appropriate particle size distribution. This study employs numerical analysis to evaluate the efficacy of partial reinforcement in reducing settlements in rock-filled lower subgrades. Column-shaped reinforcement areas strategically positioned at regular intervals in the lower subgrade induce soil arching in the upper subgrade, leading to a concentration of soil loads on the reinforced areas and consequent settlement reduction. The analysis employs finite element methods to investigate the influence of the size, stiffness, and spacing of the reinforced areas on settlement reduction in the lower subgrade. The numerical results guide the formulation of an optimal design approach, proposing a method to determine the minimum spacing required for reinforcements to effectively limit settlements within acceptable bounds. This research contributes valuable insights into addressing the challenges associated with settlement in concrete slab tracks, offering a basis for informed decision-making in railway infrastructure management.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.17 no.2
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• pp.83-92
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• 2024

Currently, various countries are enhancing accessibility by providing bicycle rental services for convenient usage within daily life. This paper introduces the Nubija public bicycle service in Changwon, South Korea, aiming to address the imbalance between demand and supply of Nubija bicycles. We propose a Highest Priority Reallocation Scheme to prevent this disparity. Comparing this scheme with others that randomly visit terminals for redistribution and those that prioritize terminals closest to current locations, we illustrate its superior efficiency. Our proposed Highest Priority Reallocation Scheme prioritizes terminals with the highest demand and shortest distances nearby. Through experiments, our proposed scheme demonstrates superior performance, with the lowest average of 817.44km distance and an average of 6437.45 times, i.e., 88.14% successful rental occurrences. This highlights its superiority over the other two algorithms.

• Journal of the Korean GEO-environmental Society
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• v.18 no.4
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• pp.13-21
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• 2017

Ballasted track has been used as track system for more than 100 years. Ballasted track has advantages of low construction cost, flexible maintenance, low noise and vibration, and so on. However, ballasted track leads to continuous settlement which causes maintenance. Recently, increase in speed, traffic volume, and weight of train requires more frequent maintenance. Fouling, well-known phenomenon of accumulation of fine materials due to intrusion of subgrade and breakage of ballast materials, expedites the settlement (i.e., irregular settlement) of track. Ground Penetrating Radar (GPR) can be one of non-destructive tools that can evaluate fouling level of ballast. In this paper, a gain function based on the attenuation characteristics of ballast material is suggested in conjunction with Hilbert transform. Lab box tests and full-scale tests indicate that the suggested method reasonably classifies clean, fouled layers, and subgrade. However, additional study to eliminate effect of sleeper and to include the scattering features of the electromagnetic wave in ballast voids should be required in order to enhance the accuracy.