• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.805-812
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• 1989

An efficient diagnostic approach for real-time operation aiding expert system in chemical process plants is discussed. The approach is based on the hybrid of the simplified symptom tree(SST) and the fault consequence digraph(FCD), representation of propagation patterns of fault states. The SST generates fault hypothesis efficiently and the FCD resolve the real fault accurately. Frame based knowledge representation and object-oriented programming make diagnostic system general and efficient. Truth maintenance system enables robust pattern matching and provides enhanced explain facilities. A prototype expert system for supports operation of naphtha furnaces process, called OASYS, has been built and tested to demonstrate this methodology. Utilization of diversified process symbolic data, produced using dynamic normal standards, overcomes the problem of qualitative Boolean reasoning and enhance the applicability.

• 한국정밀공학회지
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• 제23권2호
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• pp.65-72
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• 2006

Downcoiler is one of the major facilities in hot strip mill operation. The key to good coiling is having good equipment, modem control systems, excellent maintenance and an understanding of coiling process. Therefore, this study aims to develop a program that is useful for calculating machine design parameters and simulating coiling process. In this study, the pinching and coiling mechanism of the downcoiler was thoroughly studied and some of operational factors and their effects on the coiling process were investigated. The software was developed to estimate engineering parameters for coiler component design and to determine optimal setting values for successful coiling operation. In order to check the accuracy and usefulness of the developed software, the simulation of the downcoiler in $\#2$ Hot Strip Mill in Pohang Works was performed. The simulation results suggested that the set-up value for unit tension could be lowered. Test coiling operation by using the lowered set-up value for unit tension resulted in much more successful coiling in the aspect of strip quality and power consumption.

• 대한산업공학회지
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• 제17권2호
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• pp.1-16
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• 1991

This paper deals with some critical activities of CAPP system such as generation of part description database, part feature recognition, process and operation selection, and sequencing method for turning operation of symmetric rotational parts. The part description database is generated by data conversion module from CAD data, and the part feature is recognized by using both pattern primitives and feature recognition rules. Machining processes and operations are selected based on machining surface features and its sequence is determined by rules acquired from process planning expert. AutoCAD is employed as CAD system and computer program is developed by using Turbo-C on IBM PC/AT compatible system.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.217-220
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• 2009

모바일 환경에서 기존의 양방향 동기화 시스템은 다수 클라이언트의 동기화를 순서대로 처리하였다. 이런 경우 처리시간이 긴 동기화 작업으로 인해 다른 클라이언트들의 동기화 작업이 오랜 시간 대기하는 문제가 있다. 이 논문에서 변경충돌이 없는 다수 클라이언트들간 동기화 작업을 다중 큐를 이용하여 동시에 수행하는 시스템을 설계 구현하였다. 또한, 동기화 작업 처리기간의 비율과 작업처리 패턴에 따른 순차적 동기화와 동시 동기화의 성능을 비교하였다.

• 한국환경과학회지
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• 제32권5호
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• pp.385-394
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• 2023

There is a need for a method that can effectively remove wastewater containing small-sized particles such as TiO₂. In this study, we attempted to remove TiO₂ wastewater using electrocoagulation-electroflotation two-step separation. The TiO₂ wastewater was effectively removed via batch electrocoagulation-electroflotation separation. However, in the batch process, the simultaneous operation of electrocoagulation and electoflotation was challenging due to the high residual turbidity. In the continuous operation, electrocoagulation and electoflotation reactors were kept separate. The turbidity removal in continuous operation was similar to that in the batch process, nevertheless, the residual Al concentration was high, leading to the conclusion that counterterm ensures against residual Al were necessary.

• Journal of Mechanical Science and Technology
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• 제20권9호
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• pp.1449-1458
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• 2006

Controlled Auto-ignition (CAI) combustion processes can be broadly divided between a CAI process that is applied to four-cycle engines and a CAI process that is applied to two-cycle engines. The former process is generally referred to as Homogeneous Charge Compression Ignition (HCCI) combustion and the later process as Active Thermo-Atmosphere Combustion (ATAC) The region of stable engine operation differs greatly between these two processes, and it is thought that the elucidation of their differences and similarities could provide useful information for expanding the operation region of HCCI combustion. In this research, the same two-cycle engine was operated under both the ATAC and HCCI combustion processes to compare their respective combustion characteristics. The results indicated that the ignition timing was less likely to change in the ATAC process in relation to changes in the fuel octane number than it was in the HCCI combustion process.

• 한국기계가공학회지
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• 제1권1호
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• pp.123-132
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• 2002

In this study, the static and dynamic characteristics of endmilling process was modelled and the analytic realization of chatter mechanism was discussed. In this regard, We have discussed on the comparative assessment of recursive time series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision endmilling operation. In this study, simulation and experimental work were performed to show the malfunctional behaviors. For this purpose, new recursive least square method (RLSM) were adopted for the on-line system identification and monitoring of a machining process, we can apply these new algorithms in real process for detection of abnormal chatter. Also, The stability lobe of chatter was analysed by varying parameter of cutting dynamices in regenerative chatter mechanics.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1028-1031
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• 1996

Dynamic scheduling is very important in constructing CIM and improving productivity of chemical processing systems. Computation at the scheduling level requires mostly a long time to generate an optimal schedule, so it is difficult to immediately respond to actual process events in real-time. To solve these problems, we developed dynamic scheduling algorithms such as DSMM(Dynamic Shift Modification Method), PUOM(Parallel Unit Operation Method) and UVVM(Unit Validity Verification Method). Their main functions are to minimize the effects of unexpected disturbances such as process time variations and unit failure, to predict a makespan of the updated dynamic schedule and to modify schedule desirably in real-time responding to process time variations. As a result, the algorithms generate a new pertinent schedule in real-time which is close to the original schedule but provides an efficient way of responding to the variation of process environment. Examples in a shampoo production batch process illustrate the efficiency of the algorithms.

• 품질경영학회지
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• 제30권1호
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• pp.97-117
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• 2002

We apply Taguchi method to the process optimization problem of chemical reaction process, and some case studies are done to find out the way for cost reduction and quality improvement The parameter and tolerance designs of Taguchi mettled are done with operation data of a chemical process and we propose a procedure how to use and analyze the operation data to find the optimal process conditions and tolerance limits. In order to use the continuous values in experiment conditions, it is suggested how to determine the interval of each level by discrete values and to treat any missing values caused from discrete 4 levels.

• 한국CDE학회논문집
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• 제19권4호
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• pp.402-409
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• 2014

Presented in this paper is a scheduling method for semiconductor backend process considering the backward pegging. It is known that the pegging for frontend is a process of labeling WIP lots for target order which is specified by due date, quantity, and product specifications including customer information. As a result, it gives the release plan to meet the out target considering current WIP. However, the semiconductor backend process includes the multichip package and test operation for the product bin portion. Therefore, backward pegging method for frontend can't give the release plan for backend process in semiconductor. In this paper, we suggest backward pegging method considering the characteristics of multichip package and test operation in backend process. And we describe the backward pegging problem using the examples.