Jong-Gyu Hwang

Design of PRT operating system based interlocking between virtual and real environment

Unlike existing general railways, PRT system is the new urban transit system which is operated non-stop to the destination of passengers on an on-demand basis by being operated in the method of off-line station based on operation lines in the form of complex networks. This PRT system is the new means of transportation that was proposed conceptually long time ago and is being test-operated at some sites in some foreign countries currently. In Korea also, studies on this PRT system which is the new means of transportation with a new concept were started, and this paper explains contents of design on operation system of PRT system as one of them. Especially, this paper explains contents of design on PRT operation control system through linkage of virtual environment to the real environment in accordance with the impossibility of securing physical spaces and manufacturing multiple vehicles in developing the new means of transportation.

Analysis of S/W Test Coverage Automated Tool & Standard in Railway System

Abstract Recent advances in computer technology have brought more dependence on software to railway systems and changed to computer systems. Hence, the reliability and safety assurance of the vital software running on the embedded railway system is going to tend toward very critical task. Accordingly, various software test and validation activities are highly recommended in the international standards related railway software. In this paper, we presented an automated analysis tool and standard for software testing coverage in railway system, and presented its result of implementation. We developed the control flow analysis tool estimating test coverage as an important quantitative item for software safety verification in railway software. Also, we proposed judgement standards due to railway S/W Safety Integrity Level(SWSIL) based on analysis of standards in any other field for utilizing developed tool widely at real railway industrial sites. This tool has more advantage of effective measuring various test coverages than other countries, so we can expect railway S/W development and testing technology of real railway industrial sites in Korea.Key Words : Railway systems, Software testing, Test coverage, Safety integrity level(SIL)

Analysis of the Formal Specification Application for Train Control Systems

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.

Formal requirements specification in safety-critical railway signaling system

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 error of overlooked requirement specification can be detected using 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’ which is formal method tools using Statechart. Also we applied the proposed method to safety-critical railway signaling systems for the formal requirement specification and analyzed the specification results.

Analysis on Software Static Testing Results of Railway Signaling System

Many function of railway signalling system which is in charge of most core function in a railway system are being operated by the software according to the development of computer technology. Accordingly, the source code testing to verify the safety of the railway signalling system software becomes to be more important, and related international standards highly recommend verifications on the source code also. For this reason, several related studies on vital source code verification were executed from several years ago in Korea. This paper performed tests through the application to railway signalling system being applied to the existing actual domestic railway sites through automated testing tools for coding rules of signalling system software and another signaling system software under development in Korea recently, and analyzed their results.

Development of Automatic Testing Tool for ‘Design & Coding Standard’ for Railway Signaling Software

In accordance with the development of recent computer technology, the dependency of railway signaling system on the computer software is being increased further, and accordingly, the testing for the safety and reliability of railway signaling system software became more important. This thesis suggested an automated testing tool for coding rules on this railway signaling system software, and presented its result of implementation. 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.

Applying formal method to train distance control system by combining zed and statechart

As the current use of computer-based control systems becomes common, the security of safety and reliability needed for systems turns to difficult. In particular, the railway signaling control system requires higher safety and reliability. Railway advanced countries, especially European countries, are performing studies and projects concerning formal methods. In Korea, however, the studies of formal methods are still behind them as the above mentioned, and there is no actual formal method application. In this paper, we first suggest the application plan of formal methods to train control systems in the domestic railway industry, and prepare an eclectic approach to incorporate Z(Zed) and statechart. And we presented application results for train distance control systems by using the proposed method. This innovative compromised scheme has not yet applied in other foreign countries, and the more predominant efficiency and the accuracy have confirmed on the basis of expected results than other existing methods.

Development of automatic testing tool for software coding rules for railway signalling

In accordance with the development of recent computer technology, the dependency of railway signaling system on the computer software is being increased further, and accordingly, the testing for the safety and reliability of railway signaling system software became more important. This thesis suggested an automated testing tool for coding rules on this railway signaling system software, and presented its result of implementation. 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.

Safety guaranteeing method & tool development in railway communication system

Safety-critical systems related to the railway communications are currently undergoing changes. Mechanical and electro-mechanical devices are being replaced by programmable electronics that are often controlled remotely via communication networks. Therefore designers and operators now not only have to contend with component failures and user errors, but also with the possibility that malicious entities are seeking to disrupt the services provided by theirs systems. Recognizing the safety-critical nature of the types of communications required in rail control operations, the communications infrastructure will be required to meet a number of safety requirements such as system faults, user errors and the robustness in the presence of malicious attackers who are willing to take determined action to interfere in the correct operation of a system. This paper discusses the safety strategies employed in the railway communications and proposes a security mechanism for Korean railway communication system. We present the developed communication safety evaluation tool based on the proposed security mechanism and also evaluate its protecting capability against the threats of masquerading, eavesdropping, and unauthorized message manipulation.

Development of Communication Protocol Verification Tool for Vital Railway Signaling Systems

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 μ-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.