• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5134-5139
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• 2013

Ladder Diagram(LD) or Sequential Function Chart(SFC) is used for the design of complex modern control system with Programmable logic controller(PLC). LD is the most widely utilized among PLC standard language. But recently, SFC is used frequently. SFC is very easy to grasp the sequential flow of control logic but is difficult for describing combinational logic. When the interrupt factor is occurred, the main program is stopped. And after the interrupt program is completed, the main program is restart. Therefore the more complex the interrupt program, the main program is interrupted downtime will be that much longer. In this paper, we propose the method for interrupt implementation without the dwell time of the main program by SFC language and confirm his feasibility through the simulation.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.146-148
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• 2010

본 논문에서는 SFC로 기술된 PLC 프로그램에서 외부 이벤트가 발생하는데 엣지동작에 관해 고찰해 본다. SFC 프로그램에서는 이벤트가 발생하는데 상승엣지와 하강엣지일 때의 이진 신호 이론을 고찰해보고, 수학적인 정의는 어떻게 정리되는지를 고찰해본다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.55-61
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• 2010

When we design the control system used Programmable Logic Controller(PLC) by Sequential Function Chart(SFC), if we use a SFC, it is easy to know the sequential flow of control, to maintenance the controller and to describe a program. We program a SFC by a unique sequence, an alternative sequence and a parallel sequence. If we program a SFC by a alternative sequence, the memory size of a alternative sequence must be larger than the memory size of a unique sequence. Therefore this thesis show an efficient method to reduce a memory size and we confirmed its feasibility through actual example.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.49-55
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• 2006

In industrial control system used by Programmable Logic Controller(PLC), ladder Diagram(LD) is the must widely utilized and plays an important role in industrial control system. But recently, the study about Sequential Function Chart(SFC) is performed actively. When we program by SFC, generally, we design one routine from start to end. This method is difficult to design, and we often make mistakes. In this paper, we propose the method that we compose each sub-system after we design each sub-system and confirm his feasibility through an actual examples.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.6
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• pp.1260-1268
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• 2005

Ladder Diagram(LD) is the most extensively used among PLC standard language for the design of control system. But LD has the disadvantages for data processing and maintenance. On the other hand, the Sequential Function Chart(SFC) graphic language is very powerful for describing the sequential logic control algorithm. SFC is based on flow chart, so control flow understanding is very easy and divergence can possible improving its ability. In this paper, we propose the efficient management elevator system using the action qualifiers and choice divergence. From the result, we confirm the SFC language reduced program memory capacity and processing time is faster than LD language.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.4
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• pp.153-158
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• 2008

When we design the control system used Programmable Logic Controller(PLC), we program the main algorithm by Ladder Diagram(LD) in many standard language. But if we use an Sequential Function Chart(SFC), we is easy to know the sequential flow of control, to maintenance the controller and to describe a program. Even though a SFC have many merits, A SFC have some problems like a condition and a function of self test. Therefore this thesis show an efficient function of self test and we confirmed its feasibility through actual example.

• Progress in Medical Physics
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• v.21 no.1
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• pp.9-15
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• 2010

Scatter radiation considerably affects radiographic image quality by reducing image contrast and contributing to a non-uniform background. Images containing a large portion of scatter radiation may result in an incorrect diagnosis. In the past few years, many efforts have been made to reduce the effects of scatter radiation on radiographic images. The purpose of this study is to accurately measure scatter fractions and evaluate the effectiveness of beam-stop arrays. To measure scatter fraction accurately, a beam-stop array and the SFC (Scatter Fraction Calculator) program were developed. Images were obtained using the beam-stop array for both an anti-scatter technique with an anti-scatter grid and an air gap technique. The scatter fractions of the images were measured using the SFC program. Scatter fractions obtained with an anti-scatter grid were evaluated and compared to scatter fractions obtained without an anti-scatter grid. Scatter fractions were also quantitatively measured and evaluated with an air gap technique. The effectiveness of the beam-stop array was demonstrated by quantifying scatter fractions under various conditions. The results showed that a beam-stop array and the SFC program can be used to accurately measure scatter fractions in radiographic images and can be applied for both developing scatter correction methods as well as systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.126-130
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• 2006

Programmable Logic Controller(PLC) is the most widely utilized and plays an important role in industrial control system. Sequential Function Chart(SFC) is a graphic language which is suitable for describing a sequential control logic in discrete control system. We can design a distribute control construction and a hierarchical control construction in process control system described by SFC. In hierarchical control structure, we construct each subsystems to synchronize a synchronous signal between subsystems, and the command system gives and takes a synchronous signal with subsystems. Therefore, the system has a low memory efficiency and a low system performance. In this paper, we propose the method that improved the efficiency of memory in hierarchical control construction, and confirm its feasibility through an actual example.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.259-262
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• 1998

DNC(Distributed Numerical controller)는 제품을 생산하기 위해 현장용 컴퓨터를 이용하여 공작기계 및 주변장치를 제어하고 감시한다. 본 논문에서는 SFC/OP(Shop Floor Control/point of Production) 시스템과 연계시키기 위한 DNC 시스템의 구조를 제시한다. 본 시스템은 도면 정보를 유기적으로 연결하여 작업절차서를 조회하고, 작업절차서 및 NC 프로그램/공구 보정 데이타를 인덱스 데이터베이스화하고, 소재·지그·공구를 연계한다. 또한 생산정보를 빠르고 능동적으로 현장 작업자에게 전달하고, 기계의 상태정보를 기계로부터 직접 수집함으로써 실시간 모니터링이 가능하다. 분석 및 설계단계에서는 실시간으로 발생하는 이벤트를 처리하기 위해 상태전이도(State Transition Diagram)를 사용한다. 서버 DBMS(Database Management System)로 관계형 데이터베이스를 채택한 Oracle을 사용하였고, 프로그램 개발도구로는 Developer 2000, Microsoft Visual C++ 5.0을 사용하여 구현한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.107-112
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• 2010

When we design the control system used Programmable Logic controller(PLC), if we program a Sequential Function Chart(SFC), It is easy to understand the sequential flow of control, to maintenance the controller and to describe a program. SFC language is programmed by a single sequence, a select sequence and a parallel sequence. In a select sequence, when the select step is error, the whole process is stopped. If the error step has no connection the whole process, the loss is down when we debugging the program without stopping the whole process. Therefore, this thesis shows the efficient method of remote control for select sequence and we confirmed its feasibility through actual example.