• 한국항공우주학회지
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• 제35권6호
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• pp.517-525
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• 2007

무인기의 운용이 점차 보편화되면서 무인기의 기본 요구도에 많은 변화가 생기고 있다. 기존의 시스템은 기능 구현을 주목적으로 하였으나 현재의 무인기는 이를 넘어서 가용성에도 큰 무게를 둔다. 따라서 무인기 분야 선진 각국에서는 시스템의 신뢰도 분석 방법과 자료 수집에 많은 노력을 기울이고, 또 그 결과를 설계에 반영한다. 본 논문에서는 이러한 신뢰성 분석 기법을 소개하고 이를 기초로 현재 개발 중인 무인기 탑재시스템을 대상으로 신뢰성을 분석하여 그 결과를 제시함으로써 무인기 개발 및 운용 과정에서의 효율성 증대를 도모하였다.

• 품질경영학회지
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• 제44권3호
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• pp.587-600
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• 2016

Purpose: This paper evaluates the performance of the pre-control(PC), an alternative to statistical process control techniques and compares with a control chart considering the tolerance of process. Methods: The previous studies for PC have drawbacks that PC with two linked stages, qualification and running, are discussed separately and independently. Hence this paper analyzes the performance of PC by integrating two stages. Results: Average outgoing quality limits to grasp the outcome of PC are provided by computational results for two process capability indexes, $C_p$ and $C_{pk}$ and the usefulness of PC from comparative experiments with modified control charts is commented. Conclusion: Helpful guidelines for quality managers to apply PC in practice and areas of process for PC to be more benefit are presented.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.158-163
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• 1986

This article surveys techniques and issues related to real time process control system developed for industrial control applications. It covers the system architecture and software engineering issues such as the design of data structures, scheduling of asynchronous task activities, management of shared resources, handling of interrupt and implementing an user friendly man-machine interface. Also problems associated with implementing a real-time system that supports dynamic configuration of data base is addressed.

• 대한안전경영과학회지
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• 제4권3호
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• pp.107-122
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• 2002

There are two approaches to process control. The one is engineering process control(EPC) which is one of the techniques very widely used in the process industry and based on control theory which aims at keeping the process on target using manipulating variable. The other is statistical process control(SPC) whose main purpose is to look for assignable causes(variability) in the process. To design an integrated or combined scheme of SPC and EPC is gaining recognition in the process experiences for hybrid industry. This paper aims to investigate recent study concerned on the integration of SPC and EPC. First, we consider the difference between SPC and EPC in simple terms and review various models of EPC for integration including evaluation of previous study. Finally, we suggest some prospective research area concerned on the integration of SPC and EPC.

• 제어로봇시스템학회논문지
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• 제13권2호
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• pp.173-178
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• 2007

This paper is to establish an appropriate model for predicting the temperature decreases in the batch transferred from the refining process to the caster in steel-making companies. Mathematical modeling of the temperature decreases between the processes is difficult, since the reaction mechanism by which the temperature changes in a molten steel batch is dynamic, uncertain and complex. Three soft computing techniques are examined using the same data, namely the multiple regression, fuzzy regression, and neural net (NN) models. To compare the accuracy of these three models, a limited number of input variables are selected from those variables significantly affecting the temperature decrease. The results show that the difference in accuracy between the three models is not statistically significant. Nonetheless, the NN model is recommended because of its adaptive ability and robustness. The method presented in this paper allows the temperature decrease to be predicted without requiring any precise metallurgical knowledge.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.53-60
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• 1998

Efficiency of design process for large scale structures highly depends on the development of efficient structural analysis and structural response control algorithms because a successful design involves a number of structural analysis based on iterative structural response control process. In this paper, distributed structural analysis model on multiple personal computers connected by ethernet network is presented. To reduce communication cost required in the process of analysis, substructuring techniques are adopted to evenly distribute computational loads on each processor. With its applications on structural analysis of plane frame structures, performance of the proposed computational model are presented in detail.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.367-371
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• 1989

A linear form of reduced-order distillation model is proposed, which contains the physical properties of distillation process and can be used in real time applications. The proposed model is linear in terms of liquid mole fraction and contains some tuning parameters. To verify the applicability of the proposed model, the model identification using nonlinear filtering techniques was applied. As a result, it was found that this model represented the simulated distillation process very closely as the parameters were converged.

• 품질경영학회지
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• 제33권1호
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• pp.1-10
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• 2005

This paper develops a new VSI $\={X}-CRL$ synthetic control chart that considers convenience of use in the field, and perception of change of process applying VSI techniques to synthetic control chart, simultaneously. We found the optimal sampling interval and various control limit factor of the suggested chart using markov chain. Comparison and analysis is carried out between synthetic VSI $\={X}-CRL$ chart and other chart in the statistical aspect; $\={X}$ control chart, VSI $\={X}$ chart, another synthetic chart. In case that the process follows normal distribution, the proposed VSI $\={X}-CRL$ synthetic control chart in detecting process mean shift showed the best performance in aspect of statistical performance, regardless of control limit L of CRL/S control chart.

• 한국IT서비스학회지
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• 제10권3호
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• pp.113-126
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• 2011

The smelting and the continuous casting of steel are important processes that determine the quality of steel products. Especially most of quality defects occur during solidification of the steel continuous casting process. Although quality control techniques such as six sigma, SQC, and TQM can be applied to the continuous casting process for improving quality of steel products, these techniques don't provide real-time analysis to identify the causes of defect occurrence. To solve problems, we have developed a detection model using decision tree which identified abnormal transactions to have a coarse grain structure. And we have compared the proposed model with models using neural network and logistic regression. Experiments on steel data showed that the performance of the proposed model was higher than those of neural network model and logistic regression model. Thus, we expect that the suggested model will be helpful to control the quality of steel products in real-time in the continuous casting process.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1360-1363
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• 1996

EPD(End Point Detection) is used to decide etching degree of layer which must be removed at wafer etching process in plasma etching process which is one of the most important process in semiconductor manufacturing. In this thesis, the method which detects malfunction of etching process in real-time will be discussed. Several EPD signal traces are collected in normal plasma etching condition and used as reference EPD signal traces. Critical points can be detected by applying differentiation and zero-crossing techniques to reference EPD signal. Mean and standard deviation of critical parameters which is memorized from reference EPD signal are calculated and these determine the lower and higher limit of control chart. And by applying statical control chart to EPD signals which are collected in real etching process malfunctions of process are detected in real-time. By means of applying this method to the real etching process we prove our method can accurately detect the malfunction of etching process and can compensate disadvantage of current industrial method.