• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.230-239
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• 1998

Though limited, Model Human Processor (MHP) has been used to explain the complex users' behaviors during human-computer interactions in a simplified manner. MHP consists of perceptual, cognitive and motor systems, each with processors and memories interacting with each other in serial or parallel mode. The important parameters of memory include the storage capacity, the decay time, and the code type of a memorized item. The important parameter of a processor is the cycle time. Using these features of the model, this study developed a computerized cognitive process simulator to predict the cognitive process time of a class match task process. An experimental validity test result showed that the mean prediction time for cognitive process of the class match task simulated 50 times by the simulator was consistent with the mean cognitive process time of the same task performed by 37 subjects. Animation of the data flow during the class match task simulation will help understand the invisible human cognitive process.

• Journal of Intelligence and Information Systems
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• v.4 no.1
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• pp.1-10
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• 1998

Process planning is a very complex task and requires the dynamic informatioon of shop foor and market situations. Process plan selection is one of the main problems in the process planning. In this paper, we propose a new process plan selection model considering operation flexibility for the computer aided process planing. The model is formulated as a 0-1 integer programming considering realistic shop factors such as production volume, machining time, machine capacity, transportation time and capacity of tractors such as production volume, machining time, machine capacity, transportation time capacity of transfer device. The objective of the model is to minimize the sum of the processing and transportation time for all parts. A genetic algorithm a, pp.oach is developed to solve the model. The efficiency of the proposed a, pp.oach is verified with numerical examples.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.2
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• pp.36-42
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• 2008

As competition shifts from being a company oriented one to a supply chain oriented, an effective SCM(supply chain management) becomes a necessary strategy for any successful businesses. But, it is not easy to form a successful SCM, because the individual desire of participants conflict with others. These desires affect the performance of SCM and cause waste of cost and time. Analyzing a supply chain of discount retailers, this paper eliminates idle time and improves the process with rearranging the reorder closing time(reorder point). For win-win strategy, this work reveals the reorder closing time is an important factor. It is possible to reduce cost and time on the entire SCM process by just changing the ordering time.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.246-255
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• 1998

This paper presents a novel method for real-time malfunction detection of plasma etching process using EPD signal traces. First, many reference EPD signal traces are collected using monochromator and data acquisition system in normal etching processes. Critical points are defined by applying differentiation and zero-crossing method to the collected reference signal traces. Critical parameters such as intensity, slope, time, peak, overshoot, etc., determined by critical points, and frame attributes transformed signal-to symbol of reference signal traces are saved. Also, UCL(Upper Control Limit) and LCL(Lower Control Limit) are obtained by mean and standard deviation of critical parameters. Then, test EPD signal traces are collected in the actual processes, and frame attributes and critical parameters are obtained using the above mentioned method. Process malfunctions are detected in real-time by applying SPC(Statistical Process Control) method to critical parameters. the Real-time malfunction detection method presented in this paper was applied to actual processes and the results indicated that it was proved to be able to supplement disadvantages of existing quality control check inspecting or testing random-selected devices and detect process malfunctions correctly in real-time.

• Design & Manufacturing
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• v.17 no.1
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• pp.56-63
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• 2023

In this study, the vibration signal of the mold was measured and analyzed to monitor the process information and characteristics during the press molding process. A necklace-type picture frame mold was used for press molding, and the vibration signal was measured by GY-61 acceleration sensor module attached to the surface of the upper (movable) mold base. The change of the vibration signal of the mold according to press speed was analyzed. As a result, the vibration signal had a large change at five sections: "Holder contact", "Punch contact and start of pressing", "End of pressing", "Mold open", and "Demolding". The time difference between "Punch contact and start of pressing" and "End of pressing" means the pressing time which is the actual time the material is molded under pressing pressure. The time intervals for each section, represented by the time interval between "Holder contact" and "Punch contact and start of pressing", can be used to compare and evaluate the press speed applied to the process. By comparing the vibration signals at 60 rpm and 90 rpm, the amplitude at the section of "Punch contact and start of pressing" increased as the press speed increased. This result means that as the press speed increases, more force and pressure is applied to the material. Also, the peak values of the other sections were found to increase as the press speed increased. It was found that the pressing time, the time interval between "Punch contact and start of pressing" and "End of pressing", decreases as the pressing speed increases. Similarly, press speed factor, the time interval between "Holder contact", and "Punch contact and start of pressing", is found to be shorter. Therefore, based on the result of this study, the pressing time, press speed, pressing(punching) pressure of each cycle can be monitored by measuring the vibration signal of the mold. Also, it was confirmed that the level and trend of process information and characterization can be evaluated as the change of the mold vibration during press molding.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.1
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• pp.92-100
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• 2008

This paper develops a process monitoring system for real-time process control. The practical case is studied on a small and medium marine equipment company. For business process reengineering of the company, we adopt an approach based on information engineering methodology, which consists of four stages : planning, analysis, design, and implementation. The system is developed for Client/Server environment. We discuss the constructing of hardware system for real-time process control at low cost. The developed system is composed of interrelated modules for item master and BOM management, process control, facility management, SQC and work report.

• Communications for Statistical Applications and Methods
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• v.7 no.3
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• pp.773-788
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• 2000

Statistical process control (SPC) and engineering process control (EPC) are based on different strategies for processes quality improvement. SPC reduces process variability by detecting and eliminating special causes of process variation. while EPC reduces process variability by adjusting compensatory variables to keep the quality variable close to target. Recently there has been needs for a process control proceduce which combines the tow strategies. This paper considers a combined scheme which simultaneously applies SPC and EPC techniques to reduce the variation of a process. The process model under consideration is an integrated moving average(IMA) process with a step shift. The EPC part of the scheme adjusts the process back to target at every fixed monitoring intervals, which is referred to a repeated adjustment scheme. The SPC part of the scheme uses an exponentially weighted moving average(EWMA) of observed deviation from target to detect special causes. A Markov chain model is developed to relate the scheme's expected cost per unit time to the design parameters of he combined control scheme. The expected cost per unit time is composed of off-target cost, adjustment cost, monitoring cost, and false alarm cost.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.140-145
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• 1994

In this paper, we consider a problem to estimate process parameters using input-output data collected from the process operating in closed-loop control system. When orders and delay-time of the process are known correctly, under some conditions of identifying experiments, it is reported that accurate identification results can be obtained by applying prediction error method. To get accurate estimates, it is necessary to know orders and delay-time of the process. It is difficult to determine them in closed-loop identification, because ill-condition for identification are easily caused by selection of unsuitable order or delay time. Furthermore, the procedures to select orders and delay-time in open-loop identification aren't always available in closed-loop identification. The purpose of this paper is to determine a delay-time under suitable assumption that order of the process are known as the first step.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1645-1650
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• 2005

FOPDT(First-Order Plus Dead-Time) and SOPDT(Second-Order Plus Dead-Time) process, which are used as the most useful process in industry, are difficult about process identification because of the long dead-time problem and the model mismatch problem. Thus, the accuracy of process identification is the most important problem in FOPDT and SOPDT process control. In this paper, we proposed the real-coded genetic algorithm for identification of FOPDT and SOPDT processes. The proposed method using real-coding genetic algorithm shows better performance characteristic comparing with the existing an area-based identification method and a directed identification method that use step-test responses. The proposed strategy obtained useful result through a number of simulation examples.

• Journal of the Korean Society of Systems Engineering
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• v.2 no.2
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• pp.21-26
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• 2006

In modern systems technology, increasingly more systems are anticipated to operate in real-time environment. These systems are usually complex to implement since it is not easy to satisfy the real-time requirement for both hardware and software components simultaneously. In this paper, we first review an object-oriented development process that was proposed earlier for software-intensive real-time system using the Unified Modeling Language (UML). We then study how to improve the problems that the UML approach might have. Applying the systems engineering(SE) process yields useful results which include : 1) an improved requirements management over the whole system life-cycle ; 2) a detailed scenario on how to carry out the SE process ; and 3) a conversion process from the text-based requirements to the UML-based graphic ones.