• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.153-158
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• 1997

This paper describes a formal safety analysis technique which is demonstrated by performing empirical formal safety analysis with the case study of beamline hutch door Interlock system that is developed by using PLC(Programmable Logic Controller) systems at the Pohang Accelerator Laboratory. In order to perform formal safety analysis, we have built the Z formal specifications representation from user requirement written in ambiguous natural language and target PLC ladder logic, respectively. We have also studied the effective method to express typical PLC timer component by using specific Z formal notation which is supported by temporal history. We present a formal proof technique specifying and verifying that the hazardous states are not introduced into ladder logic in the PLC-based safety critical system.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.877-880
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• 1991

In this paper, the architecture of a dataflow logic solving processor for programmable logic controller is proposed. As the proposed DFLSP(dataflow logic solving processor) is designed based on the dataflow architecture, it has inherently concurrent processing and data synchronization capabilities. And also, it has dynamic load balancing capabilites which increases the utilization of the whole system that can he hardly implemented in other multiprocessor system. The re-matching unit gets rid of unnecessary matching cycles in LSU, which increases the performance of LSU and allows the multiple input multiple output operations.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.1
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• pp.53-59
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• 1996

An automatic verification method has been studied to determine the safety and operability of programmable logic controller (PLC) based systems. For the systematic and efficient verification, we have developed a conversion method from relay ladder logic (RLL) to the verification system description. RLL is a common representation used to document PLC programs for the sequential logic of the system such as the safety interlocks and the startup/shutdown procedures. Once the modules are developed, complex RLLs can be represented by the combination of modules. As a result we can verify complex PLC systems using the verification method including RLL modules. The developed modules are used to verify alarm systems and show that the method is valid.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.772-774
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• 1998

MMIS System of KNGR is composed of systems by using of digital equipment in general, and also interface function among systems is completed by a network. According to this, KNGR PCS also got rid of many kinds of interface cards which have been used for hardwired interface to outside system, and most of function in these cards is to be programmed by PLC. This paper defines the function and method which is to be programmed to PLC. And this paper presents new function which is to be added for operator's interface by using network. It is expected that PCS logic cabinet will be more simplified, satisfy KNGR design concept, and operation convenience will be increased.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.12 no.2
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• pp.54-61
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• 1998

Ladder Diagram(LD) is the most extensively used among Programmable Logic Controller(PLC) standard languages for the design of process control system with PLC. But LD has the disadvantages for data processing and maintenance. On the other hand, there is full support for describing sequences so that complete sequential behavior can be easily broken down using a concise graphical language called Sequential Function Chart(SFC). Inspite of those characteristics, SFC is not suitable for describing interlock logic. In this paper, we propose the method for implementing interlock logic by using conventional SFC compiler and verify the effectiveness by applying proposed scheme to the In-Line Spin Coater.Coater.

• Journal of KIISE:Software and Applications
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• v.35 no.3
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• pp.149-161
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• 2008

As Programmable Logic Controllers(PLCs) are frequently used to implement real-time safety critical software, testing of PLC software is getting more important. We propose a structural testing technique on Function Block Diagram(FBD) which is one of the PLC programming languages. In order to test FBD networks, we define templates for function blocks including timer function blocks and propose an algorithm based on the templates to transform a unit FBD into a flowgraph. We generate test cases by applying existing testing techniques to the generated flowgraph. While the existing FBD testing technique do not consider infernal structure of FBD to generate test cases and can be applied only to FBD from which the specific intermediate model can be generated, this approach has advantages of systematic test case generation considering infernal structure of FBD and applicability to any FBD without regard to its intermediate format. Especially, the proposed method enables FBD networks including timer function blocks to be tested thoroughly. To demonstrate the effectiveness of the proposed method, we use trip logic of bistable processor of digital nuclear power plant protection systems which is being developed in Korea.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.11a
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• pp.296-299
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• 2007

본 논문에서는 전기로 합금철 투입 중량을 보다 정밀하게 제어하기 위하여 퍼지 함수를 사용한 제어 기법을 적용하였다. 합금철 중량 제어에 사용된 퍼지 제어는 기존 단순 패턴 제어에 비하여 합금철 계량 정밀도를 높였으며, 합금철 계량 시간을 크게 단축시켰다. 한편 퍼지 제어 함수는 제어수식을 일반화시켜서 Programmable Logic Controller (PLC)의 래더 프로그램으로 구현하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.91-96
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• 1996

The Dynamic Safety System (DSS) is a compute. based reactor protection system that has fail-safe nature and perform dynamic self-testing. In this paper, the implementation of DSS in PLC is presented for PWR. In order to choose adequate PLC implementation model of DSS, the reliability analysis is performed. The KO-RI unit 2 Nuclear power plant is selected as the reference plant, and the verification is carried out using the KO-RI unit 2 simulator FISA-2.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.310-315
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• 2005

This paper describes the development of on-line Programmable Logic Controller (PLC) laboratories to teach the detailed operation of a PLC using distance learning approach. The PLC has become a key component to provide intelligence for machines in CIM environment. This study introduces a case study that teaches PLC programming in distance learning environment. The study describes the contents of PLC laboratories and workstation set ups. The study concludes with problems found and proposes the ways to improve the on-line laboratories.

• IE interfaces
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• v.18 no.4
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• pp.412-417
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• 2005

This paper describes the development of on-line Programmable Logic Controller(PLC) laboratories to teach the detailed operation of a PLC using distance learning approach. The PLC has become a key component to provide intelligence for machines in CIM environment. This study introduces a case study that teaches PLC programming in distance learning environment. The study describes the contents of PLC laboratories and workstation set ups. The study concludes with problems found and proposes the ways to improve the on-line laboratories.