• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.358-362
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• 2004

Verification and testing are complementary techniques that are used to increase the level of confidence in the correct functioning of communication systems as prescribed by their specifications. This paper presents an experience of model checking for a formal railway signaling protocol specified in LTS (Labeled Transition System). This formal approach checks deadlock, livelock and reachability for the state and action to verify whether properties expressed in modal logic are true on specifications. We also propose a formal method for semi-automated test case generation for a railway signaling protocol described in I/O FSM (Input/Output Finite State Machine). This enables the generation of more complete and consistent test sequence for conformance testing. The above functions are implemented by C++ language and included within RSPVTE (Railway Signaling Protocol Verification and Testing Environment).

• Journal of the Korean Society for Railway
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• v.6 no.2
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• pp.135-141
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• 2003

According to the computerization of railway signaling systems, the interface link between these signaling equipment is also replaced by digital communication channel, expecially communication link for interface between EIS and LDTS, but there are some problems in the present state of railway signaling. First of all, different communication protocol is applied to interface between above two signaling equipment although they have same functions. The other is that the communication protocol currently used in railway field has some unreasonable points such as structure, formation of byte, error correction scheme and etc. To solve these problems, the standard communication protocol for railway signaling is designed. The structure of designed communication protocol and the results of performance analyses are represented in this paper. It will be expected the increase of safety, reliability and efficiency of maintenance of signaling system by using of the designed communication protocol for railway signaling.

• 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 Electrical Engineering and Technology
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• v.1 no.4
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• pp.513-519
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• 2006

As a very important part in development of the protocol, verifications for developed protocol specification are complementary techniques that are used to increase the level of confidence in the system functions by their specifications. Using the informal method for specifying the protocol, some ambiguity may be contained therein. This indwelling ambiguity in control systems can cause the occurrence of accidents, especially in the case of safety-critical systems. To clear the vagueness contained in the designed protocol, we use the LTS (Labeled Transition System) model to design the protocol for railway signaling. And then, we verify the safety and the liveness properties formally through the model checking method. The modal ${\mu}$-calculus, which is an expressive method of temporal logic, has been applied to the model checking method. We verify the safety and liveness properties of Korean standard protocol for railway signaling systems. To perform automatic verification of the safety and liveness properties of the designed protocol, a communication verification tool is implemented. The developed tools are implemented by C++ language under Windows XP. It is expected to increase the safety and reliability of communication protocol for signaling systems by using the developed communication verification tool.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.2044-2049
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• 2009

Recent advances in computer technology have brought more dependence on software to railway signaling systems. Hence, the safety assurance of the vital software running on the railway signaling system is very critical task and yet, not many works have been done. While much efforts have been reported to improve electronic hardware's safety, not so much systematic approaches to evaluate software's safety. In this paper, we suggested an automated analysis tool for S/W change impact in railway signaling system, and presented its result of implementation. The analysis items in the implemented tool had referred to the international standards in relation to the software for railway signaling system, such as IEC 61508 and IEC 62279. In these international standards, 'change impact analysis' for railway signaling system S/W has to be required mandatorily. The proposed tool can be utilized at the assessment stage and also the software development stage.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.269-275
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• 2000

The railway signaling system consists of microcomputerized vital devices on board and ground, which are connected to one another by track circuits, and interlocking equipment for route control. Therefore it is important to validate the required functions of developed system and interface between developed signaling systems. To verify the conditions and functions of signaling logic, the laboratory prototype test bench, which consists of personal computers with software module and Ethernet LAN, will be developed. In this paper general design of signaling system test bench for high-speed rail is described and developed software module is presented.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1495-1500
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• 2004

The interface link for railway signaling systems is generally point-to-point communication scheme, but there have been several efforts to apply the network technology to these interface link in overseas country. However general Ethernet scheme has several drawbacks, so this scheme cannot meet the very high reliability, safety and real-time properties. To overcome these drawbacks, there have been studies reduction and modeling of data collision probability for this ethernet at the industrial and academic world. Therefore, in this paper we analyzed describe a interface trend using network technology between railway signaling equipments and will describe a major technology and framework of a network for railway signaling system.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1259-1265
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• 2004

Railway is an important transportation tool for nation's industrial development and public daily life. These days the concern about railway has remarkably been rising due to the April 2004 opening of KTX, Korea High Speed Rail, together with Trans-Continental Railways linking North Korea, China, Russia, through European countries. In the meantime, the issues of train safety and efficiency, arising from the different on-board signaling systems installed on different kinds of trains, have been raised incessantly. In this paper CTCS(Continental Train Control System) is suggested, which can accommodate such various signaling functions as ATP, ATC, ATS, etc. into one single type of on-board signaling system and operate without changing ground signaling systems on the junctions of the Trans-Continental Railways. The development of this CTCS would cause speed-up of exiting lines and possession of railway core solutions for establishing Northeast Asia logistics center bases, which could be an important cornerstone for domestic railway improvements and Korea's role of Northeast Hub.

• 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.

• Journal of the Korean Society of Safety
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• v.25 no.1
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• pp.93-101
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• 2010

As safety-related regulations for signaling systems are standardized to IEC 61508/62278/62425, and others at the international level, safety activities and its assessment are required to be performed. And also there is the need to develop technologies for safety improvement to secure safety signaling systems in terms of technologies for safety activities on each life-cycle. In this paper we have developed the safety activity processes and technologies each steps of proposed processes respectively for railway signaling systems. And the proposed process and technologies are applied to the safety activities for mock-up signaling systems.