• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.379-385
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• 2007

Recently, vital devices of the railway signaling systems have been computerized in order to ensure safe train operation. Due to this computerization, we have gradually come to need networking interfaces between these devices. Thus it is important that there be reliable communication links in the signaling systems. Network technologies are applied in the real-time industrial control system, and there are numerous studies to be carried out on the computer network technology for vital control systems such as railway signaling systems. For deploying the studies, we consider costs, reliability, safety assurance technique, compatibility, and etc. In this paper, we propose the Ethernet for railway signaling systems and also precisely describe the computer network characteristics of vital railway signaling systems. Then we demonstrate the experimental results of the proposed network algorithm, which is based on switched Ethernet technology with redundancy scheme.

• International Journal of Safety
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• v.8 no.2
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• pp.31-36
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• 2009

In accordance with the development of recent computer technology, railway signaling software became more complex for the intellectualization. Therefore the importance and dependency of railway signaling system on the computer software is getting more increased further, and the testing for the safety and reliability of railway signaling system software became more important. It is started to become influential as very important issue for the reliability and safety of vital embedded software like railway signaling system. The software coding which can have an effect on the safety at the coding level of software shall not be included preferentially, for the safety of software, and must be checked. This thesis suggested an automated testing tool for coding rules on this railway signaling system software, and presented its applied result for railway signaling system software. The testing items in the implemented tool had referred to the international standards in relation to the software for railway system and MISRA-C standards. This automated testing tool for railway signaling system can be utilized at the assessment stage for railway signaling system software also, and it is anticipated that it can be utilized usefully at the software development stage also.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.299-306
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• 1999

The ${\mu}$-processor based-controlled system is widely used in railway signaling system. The railway signaling systems are highly required safety and reliability. It is necessary to have a fault-tolerant and fail safe concept in ${\mu}$-processor based railway signaling system. In this paper, several architectures and circuits of fault-tolerant computer system is reviewed. The basic concept of the fault-tolerant computer system will be adapted total self checking, strong fail safe, fault display circuit, logic testing circuit and system switching concepts.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.319-326
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• 2001

Railway signaling safety system organizes equipments and facilities of railway, increases transport efficiency and assures safe operation of railway. In the early days of signaling system railway managers made sure of safety by using relay logic technology based on fail-safe concept. But the development result of computer and science having been introduced to railway industry, railway signaling equipments begin to be operated through micro electronic control system. Accordingly high speed and high density operation of train became possible. Software reliability and safety technology that controls important systems of railway was highlighted. In the middle of 1990s the standard or guideline of railway reliability and safety were studied and established, and are being reviewing in Europe, Japan etc. Our reliability and safety technology have depended largely on foreign countries. In this study we performed a basic study about the reliability of software that controls the railway signaling system.

• Journal of the Korean Society for Railway
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• v.1 no.1 s.1
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• pp.10-19
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• 1998

Described in this paper is the software to design of a railway interlocking table, which describes the functional specifications of an interlocking device. Interlocking tables has been designed mainly based on personal expertise among signal engineers. However, this expertise needs to be analyzed with technical uniformity and integrated in an organized system. The proposed software is amount to the signal engineer's expertise, yet a generalization of interlocking reasoning. The algorithm is based on the train route setting principle, and is applicable in solving practical problems by computers. The software was evaluated through man-made and machine-made interlocking tables are compared. The evaluation results proves the software to be effective for computer control of the signaling system as interlocking system with a much improved safety.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1252-1253
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• 2011

The railway signaling system is being converted to the computer system from the existing mechanical device, and the dependency on software is being increased rapidly. Though the size and degree of complexity of software for railway signaling system are slower than the development speed of hardware, it is expected that the size will be grown bigger gradually and the degree of complexity will be increased also. Accordingly, the validation of reliability and safety of embedded software for train control system was started to become influential as the important issue. In this paper, we presented boundary value analysis tool for railway signaling system software, and presented its result of implementation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.9
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• pp.55-65
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• 2004

ATM was recommended by the ITU and ATM Forum as a means of transportation for B-ISDN. At this time, due to the comprehensive mature of ATM protocol, ATM has been adapted as the backbone system for carrying Internet traffi $c^{[1,2,3,4]}$. But major conceptsregarding the ATN protocol will be used on future technology. This paper presents preventive congestion control mechanisms for detecting HTR(Hard-To Reach) code in ATM systems, in particular for an improved HTR call registration method using network signaling information will discussed. In high speed circuit switching system environments, a fast HTR control mechanism is necessary. We present research results for improving HTR call registration and control methods using network signaling information and fuzzy control mechanisms. We concluded that it showed fast congestion avoidance mechanisms with a fewer system load maximized the efficiency of network resources by restricting ineffective machine attempts.

• ETRI Journal
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• v.39 no.1
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• pp.41-50
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• 2017

In connection-oriented data transport services, data loss can occur when a service experiences a problem in its end-to-end path. To resolve the problem promptly, the data transport systems providing the service must quickly modify their internal configurations, which are distributed among different locations within each system. The configurations are modified through a series of problem (event) handling procedures, which are carried out by multiple control processors in the system. This paper proposes a provisioning-to-signaling method for inter-control-processor messaging to improve the time efficiency of event processing. This method simplifies the sharing of the runtime event, and minimizes the time variability caused by the amount of event data, which results in a decrease in the latency time and an increase in the time determinacy when processing global events. The proposed method was tested for an event that required 4,000 internal path changes, and was found to lessen the latency time of global event processing by about 50% compared with the time required for general methods to do the same; in addition, it reduced the impact of the event data on the event processing time to about 30%.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.641-646
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• 2004

Computer system is widely used for controlling systems such as nuclear power plant, train speed control and air plane control. The failure of computerized controlling system can be arrived to catastrophic accident, so the safety ensuring of computerized controlling system is very important. This paper shows how to improve and ensure the safety of computerized systems. In this paper, we show how to identify, analyze hazards of the computerized system and to demonstrate risk of the system. Finally, we show how to adopt safety techniques for improving safety of the target system.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.452-464
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• 2015

This paper proposes a DC microgrid operational strategy and control method for improved service reliability. The objective is to supply power to as many non-critical loads as possible, while providing an uninterrupted power supply to critical loads. The DC bus signaling method, in which DC voltage is an information carrier, is employed to implement the operational strategy in a decentralized manner. During grid-connected operation, a grid-tied converter balances the power of the microgrid by controlling the DC voltage. All loads are connected to the microgrid, and operate normally. During islanded operation, distributed generators (DGs), a backup generator, or an energy storage system balances the power. However, some non-critical loads may be disconnected from the microgrid to ensure the uninterrupted power supply to critical loads. For enhanced service reliability, disconnected loads can be automatically reconnected if certain conditions are satisfied. Control rules are proposed for all devices, and detailed microgrid operational modes and transition conditions are then discussed. Additionally, methods to determine control parameter settings are proposed. PSCAD/EMTDC simulation results demonstrate the performance and effectiveness of the proposed operational strategy and control method.