• Journal of the Korean Society for Railway
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• v.14 no.1
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• pp.6-10
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• 2011

This article deals with a problem of setting reliability targets of the railroad systems where the punctuality target is given to the operator and a penalty is imposed for the year when the target is not met. The operator should set the reliability targets of the railroad system and sub-systems because the reliability affects the expected number of years when the penalty is imposed. This paper presents a procedure for setting the service reliability target and equations to calculate the expected number of years when the penalty is imposed and the probability that the operator should pay the penalty per year according to the mean kilometer between service failures of the railroad system and sub-systems.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1183-1184
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• 2007

Light Rail Transit (LRT) is optimized vehicle system for complex urban circumstance. LRT systems have many merits such as improved accuracy and safety. There are many LRT systems such as monorail, tram, automated guideway transit, linear induction motor propulsion and so on. These systems have been operated in Japan and other advanced countries. In Korea, local government has many projects to apply the advanced LRT system. But there are no standards regulation, performance test regulation and construction regulation for monorail system, linear induction motor system and tram in Korea. We expect that standardization brings economical construction and safety. The linear induction motor system has been usually applied to subway in Japan and ART(Advanced Rapid Transit) in Canada. In Korea, the linear induction motor system has been adopted for Yong-In LRT and currently under construction. This paper presents signalling system and TCMS(train control and monitoring system) of linear induction motor system.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.283-289
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• 2014

Personal rapid transit(PRT) systems have been highlighted in future transportation developments as a result of their potential as sustainable and eco-friendly transport solutions that provide demand-responsive mobility services. One of the most important characteristics of the personal rapid transit system(PRT) is that it can be constructed and operated at a low cost. A fundamental study on the alignment of the PRT guideway considering running stability was conducted in the present study. In addition, a parameter analysis of the major alignment design variables such as curve radius, transition curve length and cant was performed by vehicle dynamic analysis and optimum guideway alignments were proposed. The analysis results suggested that the theoretical values were satisfied and also confirmed the possibility of reducing the standard.

• Journal of the Korean Society for Railway
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• v.15 no.6
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• pp.558-565
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• 2012

Abnormal climate or weather is more frequently reported nowadays due to the global climate change. Especially, extremely low temperature in winter season may cause bad thermal discomfort of passengers. In this study, the effect of car heating modes on cabin temperature change and distribution was studied by using a real-scale environmental chamber for passenger cabin. It was found that the cabin temperature rose quickly at the initial stage of heating system operation, but it stopped increasing after certain point. And, temperature was higher when the height from the floor was higher. Based on the obtained result, the way to minimize the decrease of passengers' thermal comfort was suggested.

• Journal of the Korean Society for Railway
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• v.18 no.4
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• pp.354-362
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• 2015

Since allowable settlement of concrete slab track is about 30mm, a lot of attention must be paid to the settlement of the earthwork (reinforced trackbed, upper subgrade, under subgrade) under the concrete track. To this end, more experimental data should be accumulated through tests for these materials. In this study, we evaluate the long-term settlement of reinforced trackbed and subgrade materials using factors such as repeated loading conditions, water content, and grain size distributions in a large triaxial test and a large oedometer test. In cases in which the performance of the reinforced trackbed layer meets the design criteria, the settlement caused by train load was considerably small. But, when the water content increases in the subgrade, unexpectedly large settlement might occur for certain grain size distributions of the subgrade materials.

• Journal of the Korean Geotechnical Society
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• v.29 no.7
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• pp.47-55
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• 2013

In the element test for coarse granular materials, the grain size distributions of the materials are often adjusted, in case the grain size of coarse material in the field is larger than the available maximum grain size of the laboratory test equipment. In this study, we carried out the large cyclic triaxial test to evaluate the effect of the grain size distribution adjustment on Young's modulus in small to intermediate strain level. The test results showed that the coarse granular materials with the adjusted grain size distribution underestimated Young's modulus of the original materials. The difference of Young's modulus was larger in small strain level than in intermediate strain level.

• Journal of the Korean Society of Systems Engineering
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• v.20 no.spc1
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• pp.65-75
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• 2024

As the demand for logistics services increases rapidly in modern society, the existing freight delivery system through road transportation is caused various problems such as traffic congestion and greenhouse gas emissions. To solve that, the development of an 'underground logistics tunnel-based cargo transportation system' is currently being considered in Korea. In order to build a new concept stable and safe logistics system, derive system design requirements and functional specifications, and reflect them at the development of target system. In this study, to make foundation for development of an "underground logistics tunnel-based cargo transportation system," define system components through analysis from a hierarchical perspective, and the functions of each component were analyzed and defined. We identified what interfaces the components have at each stage of the operating process. Lastly, we defined a detailed operation scenario based on the previously derived results, deriving target system functional requirements.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.189-197
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• 2022

Today, we are exposed to various text-based media such as newspapers, Internet articles, and SNS, and the amount of text data we encounter has increased exponentially due to the recent availability of Internet access using mobile devices such as smartphones. Collecting useful information from a lot of text information is called text analysis, and in order to extract information, it is performed using technologies such as Natural Language Processing (NLP) for processing natural language with the recent development of artificial intelligence. For this purpose, a morpheme analyzer based on everyday language has been disclosed and is being used. Pre-learning language models, which can acquire natural language knowledge through unsupervised learning based on large numbers of corpus, are a very common factor in natural language processing recently, but conventional morpheme analysts are limited in their use in specialized fields. In this paper, as a preliminary work to develop a natural language analysis language model specialized in the railway field, the procedure for construction a corpus specialized in the railway field is presented.

• Journal of Mechanical Science and Technology
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• v.16 no.6
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• pp.776-784
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• 2002

We have performed experimental studies for the improvements of pneumatic brake systems of freight trains. Currently, most of the freight trains operated by the Korean National Railroad have either empty-load or diaphragm type brake systems. In this study, appropriate methods that the air pressure characteristics in both type of brake systems are in accordance with each other have been investigated. We have also performed running tests using a 30 car-train set to design optimum capacity of a quick release valve. The test results show that the quick release valve is considerably effective in shortening the release time of the diaphragm type brake system. In the case of a normal brake application, the diaphragm type brake system with the quick release valve reduces the release time to 34% of that of the system without the quick release valve. This release time is almost equivalent to that of the empty-load type brake system. Accordance of braking performance in different types of brake systems in a train set is expected to prevent wheel flats and to reduce maintenance costs.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.87-92
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• 2009

Many critical control systems are developed using formal methods. When software applied to such systems is developed, the employment of formal methods in the software requirements specification and verification will provide increased assurance for such applications. Earlier errors of overlooked requirement specification can be detected using the formal specification method. Also, the testing and full verification to examine all reachable states using model checking to undertake formal verification are able to be completed. In this paper, we proposed an eclectic approach to incorporate Z(Zed) formal language and 'Statemate MAGNUM', formal method tools using Statechart. Also we applied the proposed method to train control systems for the formal requirement specification and analyzed the specification results.