• 한국철도학회논문집
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• 제6권2호
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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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권6호
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• pp.380-387
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• 2004

In accordance with the computerization of railway signaling systems, the interface link between the signaling systems has been replaced by a digital communication channel. At the same time, the importance of the communication link has become increasingly significant. However, there are some questionable matters in the current state of railway signaling systems in KNR. First, different communication protocols have been applied to create an interface between railway signaling systems although the protocols have the same functions. Next, the communication protocols currently used in the railway fields have some illogical parts such as structure, byte formation, error correction scheme, and so on. To solve these matters, the standard communication protocol for railway signaling systems is designed. The newly designed protocol is overviews in this paper. And the simulation is performed to analysis the performance of data link control for designed protocol. According to this simulation, it is identified that the link throughput of new protocol is improved about 10% and the frame error rate is improved than existing protocol. And it is verified the safety and liveness properties of designed protocol by using a formal method for specifying the designed protocol. It is expected that there will be an increase in safety, reliability and efficiency in terms of the maintenance of the signaling systems by using the designed communication protocol for railway signaling.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권4호
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• pp.195-201
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• 2003

In accordance with the computerization of railway signaling systems, the interface link between signaling equipment has been replaced by a digital communication channel and the importance of this communication link has become increasingly significant. However, there are some problems with the present state of railway signaling. First, different communication protocol is applied to interfaces between signaling although they have the same functions. Next, the communication protocols currently used in the railway fields contain various illogical components such as structure, byte formation, error correction scheme and so on. To solve these matters, a new data link protocol for railway signaling systems is designed. In this paper, the structure of protocol and the results of performance analyses are presented. It will be expected to increase the safety, reliability and efficiency of maintenance of signaling systems by using the designed communication protocol for railway signaling in Korea.

• 한국철도학회논문집
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• 제7권2호
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• pp.114-119
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• 2004

According to the computerization of railway signalling systems. the communication protocol for interface between these systems are required. Therefore the new communication protocol for railway signaling system is required. Generally, there are two verification method for new designed protocol in the industrial and academic fields. One is the laboratory testing method which is very popular and general technique. In our research the comparison between existing and new designed protocol for signaling is described and the verification test results are also represented. From these laboratory test, we are verified the conformance of new designed protocol. Another method is verified by formal method. The format verification method is widely used at safety-critical system design but this approach is nor popular at verification communication protocol. However it is very important to verify the safety of new designed protocol for railway signaling system because signaling systems are very safety-critical systems. So, the methodology for formal verification of designed protocol is also reviews in this paper.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.354-357
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• 2004

According to the computerization of railway signaling systems, the interface link between the signaling systems has been replaced by the digital communication channel. At the same time, the importance of the communication link is more pronounced than in the past. In this paper, new network-based protocol for Korean railway signaling has designed between CTC and SCADA system, and the overview of designed protocol is briefly represented. Using the informal method for specifying the communication protocol, a little ambiguity may be contained in the protocol. To clear the ambiguity contained in the designed protocol, we use LTS model to design the protocol for this interface link between CTC and SCADA, the LTS is an intermediate model for encoding the operational behavior of processes. And then, we verify automatically and formally the safety and the liveness properties through the model checking method. Especially, the modal ${\mu}$-calculus, which is a highly expressive method of temporal logic that has been applied to the model checking method. It will be expected to increase the safety, reliability and efficiency of maintenance of the signaling systems by using the designed protocol for railway signaling in Korea.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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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 Electrical Engineering and Technology
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• 제1권4호
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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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권9호
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• pp.485-490
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• 2006

According to the computerization of railway signaling systems, the interface link between the signaling systems has been replaced by the digital communication channel. At the same time, the importance of the communication link is more pronounced than before. In this paper, new Network-based protocol between railway signaling and SCADA (Supervisory Control and Data Acquisition system) has designed and the overview of designed protocol is briefly represented. And also this paper addresses analysis of newly designed train control systems. Fame error rates of the data transmissions are calculated and compared for the two cases that the CTC (Centralized Traffic Control)/SCADA has an extra data transmission error control (CRC16) besides the inherent error control of the Ethernet and that the CTC/SCADA has no extra data transmission error control. With simulation results it has been verified that the additional error control code contributes to lowering the frame error rate. It will be expected to increase the safety, reliability and efficiency of maintenance of the signaling systems by using the designed protocol for railway signaling system.

• International Journal of Safety
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• 제6권2호
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• pp.38-42
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• 2007

As railway signaling system is computerized, the significance on safety demonstration and assessment has been increased. Therefore, railway signaling system should reflect the needs for safety assessment technique. Various studies on safety assessment technique for railway signaling have been made in Europe and standardization of the requirements for safety acceptance has been initiated by IEC. In order to develop and establish the safety assessment techniques for railway signaling in Korea, we try to review safety assessment activities for signaling system via reviewing relevant case studies and consulting with experts. And also we propose the safety assessment activity/methodology for Korean railway signaling system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.396-405
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• 2009

열차제어 지상신호시스템에서 핵심적인 철도보안기능을 수행하는 연동장치는 철도산업의 안전성 확보 지침에 따라 높은 안전성과 신뢰성을 갖추어야만 한다. 따라서 연동장치는 높은 안전성과 신뢰성을 달성할 수 있도록 실시간 운영체제 및 그 구성 하드웨어의 랜덤 고장에 대처하기 위한 Fail-Safe형 다중 제어시스템으로 구성된다. 이러한 구성에서는 운영자 인터페이스를 포함한 다양한 장치와의 메시지 교환을 위한 인터페이스 가능을 구현하기 어려운 특성이 존재한다. 본 논문에서는 연동장치와 상위 인터페이스 설비간의 통신기능을 구현하기 위한 Dual Ethernet 네트워크 구성 및 DPST (Dual Packet Seamless Transfer) 통신 프로토콜을 제안한다. 제안된 시스템의 구성에서는 특정 네트워크 장비의 랜덤 고장이나 통신오류에 강인한 특성을 보이며 통신채널의 장애를 검출할 수 있는 기능이 추가되어 설비의 유지보수에 효과적인 정보로 활용될 수 있음을 실험적으로 검증한다. 제안된 네트워크 구성 및 운영 프로토콜을 현대제철 전용철도용 전자연동장치에 구현하고 그 성능과 특성을 유럽표준규격 EN50159의 지침을 토대로 타당성을 분석한다.