• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.452-457
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• 1999

The recent control system has been changed into the type of PLC(Programmable Logic Controller) control. Up to now, systematic approach of PLC programming or control logic design is not suggested. In this study, the design process of the control logic is systematized and concrete process in each step is suggested. This systematized approach lead developer to be convenient to implement control system. When some error is occurred in the system, this approach enable the developer to analyze the reason of error rapidly and the system is amended according to systematic information of the analysis. The example of control system implementation following this approach is introduced.

• 조명전기설비학회논문지
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• 제19권3호
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• pp.127-133
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• 2005

PLC는 산업용 제어시스템에서 가장 많이 사용되며, 중요한 역할을 하고 있다. 이러한 PLC에서 사용되는 언어에 대한 연구도 활발히 이루어지고 있다. PLC에서는 LD언어가 가장 많이 사용되고 있다. LD언어는 데이터의 흐름을 알 수 없고, 유지보수가 어렵다. 반면에 SFC는 제어의 흐름을 이해하기 쉽고 유지보수가 용이하지만 조건과 인터록 기술에 문제점이 있다. 본 논문에서는 매니지먼트 스텝을 사용한 인터록의 기술에 대한 방법을 제안하였고, 실례를 통해 그의 타당성을 확인하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(1)
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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.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권12호
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• pp.1271-1282
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• 2005

PC-based control은 현재 제어분야에서 비약적 발전을 하고 있으나 일반 사용자들이 PC에서 PLC 프로그래밍하기에는 어렵다는 단점이 있다. 따라서 본 논문은 국제 PLC 표준언어로 제정된 5가지 언어 중 $90\%$이상 사용하는 LD언어에 대한 표준규격을 연구하고, 이것을 중간코드인 IL(Instruction List) 언어로 변환하고 기존 상용화된 편집기(Visual C++)에서 활용 가능한 표준 C코드로 변환함으로써 LD에 익숙한 사용자나 고급언어에 익숙한 사용자 모두 사용할 수 있는 편집기 및 실행엔진 기능을 갖춘 지능적 에이전트 기반의 통합 시스템 ISPLC(Intelligent Agent System based Software Programmable Logic Controller)를 개발하였다. ISPLC에서는 LD에서보다 C에서 논리오류 검출기능이 훨씬 용이하며, GUI기반 인터페이스를 제공하며 에이전트에 의한 프로그래밍 코드를 제공하므로 가독성이 높다. 이러한 LD->H->C로의 코드변환체제에 관한 연구는 국내외적으로 처음 시도되는 연구이다. ISPLC를 실제 실시간 교통량 제어 시스템(Real Time Traffic Control System)에 적용하여 현장 적응성이 우수한 실행엔진을 개발하여 시뮬레이션 하였으며, ISPLC는 오류검색 뿐 아니라 프로그래밍 시간을 매우 단축시켜줌을 알 수 있었다.

• 산업경영시스템학회지
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• 제19권37호
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• pp.171-178
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• 1996

The programmable logic controller(PLC) programming has been manually carried out, which might cause the productivity decrease by omission and repetition of instruction. Recently, the knowledge-based automatic programming system is introduced. In the system, input/output(I/O) addresses are input by user. In this study, we developed the prototype system for automatic I/O addressing using knowledge-based technology, With the developed system, the PLC addressing task can he consistently and effectively performed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.233-238
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• 2000

CNC machine tool is assembled by central processor, PLC(Programmable Logic Controller), and actuator. The sequential control of machine generally controlled by a PLC. The main fault occured at PLC in 3 control parts. In LC faults, operational fault is charged over 70%. This paper describes diagnosis model and data processing for remote monitoring and diagnosis system in machine tools with open architecture controller. Two diagnostic models based on the ladder diagram. Logical Diagnosis Model(LDM), Sequential Diagnosis Model(SDM), are proposed. Data processing structure is proposed ST(Structured Text) based on IEC1131-3. The faults from CNC are received message form open architecture controller and faults from PLC are gathered by sequential data.. To do this, CNC and PLC's logical and sequential data is constructed database.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1189-1192
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• 1996

In this paper, a fault diagnosis method is proposed for self-diagnostics of PLC(Programmable Logic Controller), process controller in industrial fields, and diagnosis of its external devices such as sensors and actuators. The aim of this research is proposition of systematic method of fault diagnosis of PLC control system and development of its equipment. A PLC fault diagnosis algorithm consists of self-diagnostics given by PLC makers, Inpuot/Output tracking method by analyzing sequence PLC programs, searching method of past fault cases in database using an expert system, and diagnosis of PLC units such as CPU, DI, and DO board. Finally usability of PLC fault diagnostic system is verified by testing a MELSEC PLC.

• 제어로봇시스템학회논문지
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• 제7권12호
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• pp.1009-1014
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• 2001

The ladder diagram (LD) for programmable logic controllers (PLCs) ar responsible for much important roles in advance industrial automation. As automated systems become more complex the design procedures of the system become more difficult as well. Hence. the design automation issues based on discrete event models(DEMs) are receiving more attention. One of the popular ways of tackling these problems is employing Petri nets. In this paper, we use the modified automation Petri net(MAPN) to model the manufacturing system and the modified token passing logic (MTPL) method conversion (ECC) algorithm based on the MAPN and the MTPL Finally, an example of the manufacturing system is provided to illustrate the proposed ECC algorithm.

• 산업공학
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• 제21권3호
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• pp.294-301
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• 2008

Agile and flexible manufacturing systems make it mandatory that a control program should have features such as agility, flexibility, and reusability in order to run manufacturing unit smoothly. PLCs are the most frequently used control program in manufacturing systems. PLC programs are mostly programmed by subcontraction, which makes correction of code very difficult. As a result, it may cause delay during down time and ramp up time which leads to big loss of revenue and goodwill. To prevent delay during the times, this paper proposes systematic process analysis and application method for programmable logic controller like LLD (Ladder Logic Diagram). The proposed method uses modified human-error investing techniques for documentation and transforming technique to program LLD from the documentation. Furthermore, this paper demonstrates an example of piston mechanism to explain the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.272-276
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• 2004

The conventional PID (Proportional-Integral-Derivative) control technique is widely used for the process control in many industries since it is simple in structure and provides the good response. Nowadays, this control technique has been developed on the Programmable Logic Controller (PLC) to use for the process control loop. However, using this technique is difficult when tuning the PID parameters ($K_p$, $T_i$ and $T_d$) to achieve the best response. Moreover, trial-and-error procedure along with the operator experiences are required to obtain the best results when tuning the PID controller parameters. This paper proposes the self-tuning PID controller based on PLC for the process control in the industries. The proposed self-tuning PID controller uses the PLC-based PID structures to control the process production. The proposed PID tuning utilizes the PLC to synthesize and analyze controller parameter as well as to tune for appropriate parameters using Dahlin method and extrapolation. Experimental results using a self-tuning PID controller to control temperature of the oven show that the controller developed is capable of controlling the process very effectively and provides a good response.