• 품질경영학회지
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• 제36권3호
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• pp.34-44
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• 2008

This research proposes a design method based on the statistical characteristics of the Shewhart control chart incorporated with 2 of 2 and 2 of 3 runs rules respectively. A Markov chain approach is employed in order to calculate the in-control and out-of-control average run lengths(ARL). Two different control limit coefficients for the Shewhart scheme and the runs rule scheme are derived simultaneously to minimize the out-of-control average run length subject to the reasonable in-control average run length. Numerical examples show that the statistical performance of the hybrid control scheme are superior to that of the original Shewhart control chart.

• 품질경영학회지
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• 제40권2호
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• pp.176-185
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• 2012

After a work of Derman and Ross(1997) that considered simple main runs rules and derived ARL (Average Run Length) using Markov chain modeling, $\bar{X}$ control chart based on diverse alternative main and supplementary runs rules that is the most popular control chart for monitoring the mean of a process are proposed. This paper reviews and discusses the-state-of-art researches for these runs rules and classifies according to several properties of runs rules. ARL derivation for a proposed runs rule is also illustrated.

• 품질경영학회지
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• 제40권4호
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• pp.467-480
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• 2012

Purpose: This paper introduces new 2-of-3 main and supplementary runs rules to increase the performance of the classical $\bar{X}$ control chart for detecting small process shifts. Methods: The proposed runs rules are compared with other competitive runs rules by numerical experiments. Nonlinear optimization problem to minimize the out-of-control ARL at a specified shift of process mean for determining action and warning limits at a time is formulated and a procedure to find two limits is illustrated with a numerical example. Results: The proposed 2-of-3 main and supplementary runs rules demonstrate an improved performance over other runs rules in detecting a sudden shift of process mean by simultaneous changes of mean and standard deviation. Conclusion: To increase the performance in the detection of small to moderate shifts, the proposed runs rules will be used with $\bar{X}$ control charts.

• 대한산업공학회지
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• 제34권3호
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• pp.308-317
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• 2008

This research investigates economic characteristics of 2 of 2 runs rules under the Shewhart $\bar{X}$ control chart scheme. A Markov chain approach is employed in order to calculate the in-control average run length (ARL) and the average length of analysis cycle. States of the process are defined according to the process conditions at sampling time and transition probabilities are derived from the state definitions. A steady state cost function is constructed based on the Lorezen and Vance(1986) model. Numerical examples show that 2 of 2 runs rules are economically superior to the Shewhart $\bar{X}$ chart in many cases.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 춘계학술대회 논문집
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• pp.184-188
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• 1999

The performance of an AGV varies with the applied AGV dispatching rule in the operation of AGVS. This study proposes a multi-attribute AGV dispatching rule. The suggested dispatching rule considers the output queue of a workstation, distance between an idle AGV and a workstation to be served, the input queue of the destination and the remaining job process of a part. This study suggests two types of and the remaining job process of a part. This study suggests two types of multi-attribute dispatching rules. One is an one-stage rule which selects the part to be served considering four attributes simultaneously. The other is a two-stage rule by which a workstation is selected and a part is chosen from the selected workstation. The simulation runs were executed under different experimental conditions to obtain preliminary statistics on the several performance measures.

• 한국시뮬레이션학회논문지
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• 제9권3호
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• pp.77-89
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• 2000

This paper suggests a multi-attribute dispatching rule for an automated guided vehicle(AGV). The attributes to be considered are the number of queues in outgoing buffers of workstations, distance between an idle AGV and a workstation with a job waiting for the service of vehicle, and the number of queues in input buffers of the destination workstation of a job. The suggested rule is based on the simple additive weighting method using a normalized score for each attribute. A neural network approach is applied to obtain an appropriate weight vector of attributes based on the current status of the manufacturing system. Backpropagation algorithm is used to train the neural network model. The proposed dispatching rules and some single attribute rules are compared and analyzed by simulation technique. A number of simulation runs are executed under different experimental conditions to compare the several performance measures of the suggested rules and some existing single attribute dispatching rules each other.

• 응용통계연구
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• 제17권3호
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• pp.459-473
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• 2004

본 논문에서는 Breiman 등(1984)의 전체탐색법이 갖고 있는 변수선택 편향을 극복할 수 있는 알고리즘을 제안하였다. 제안한 알고리즘은 노드의 분리 변수를 선택하는 단계와 그 선택된 변수에 대해서만 이진분리를 위한 분리점을 찾는 단계로 나뉘어져 있다. 예측변수가 연속형 일 때는 스피어만의 순위상관계수에 의한 검정을 수행하고, 범주형일 때는 크루스칼-왈리스의 통계량에 의한 검정을 수행하여 통계적으로 가장 유의한 변수를 분리변수로 선택하였고 Breiman 등(1984)의 전체탐색법을 그 변수에만 적용하여 노드의 분리기준을 정하였다 모의실험 연구를 통해 Breiman등(19히)의 CART와 제안한 알고리즘을 변수선택 편의, 변수선택력파 평균제곱오차 측면에서 서로 비교하였다. 아울러 두 알고리즘을 실제 자료에 적용하여 효율을 서로 비교하였다.

• 품질경영학회지
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• 제22권1호
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• pp.82-95
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• 1994

When independent individual measurements are taken both $S/c_4$ and $\bar{R}/d_2$ are unbiased estimators of the process standard deviation. However, with dependent data $\bar{R}/d_2$ is not an unbiased estimator of the process standard deviation. On the other hand $S/c_4$ is an asymptotic unbiased estimator. If there exists correlation in the data, positive(negative) correlation tends to increase(decrease) the ARL. The effect of using $\bar{R}/d_2$ is greater than $S/c_4$ if the assumption of independence is invalid. Supplementary runs rule shortens the ARL of X control charts dramatically in the presence of correlation in the data.

• 대한교통학회지
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• 제8권1호
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• pp.5-15
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• 1990

As a result of the lack of methodology for the determination of navigational channel capacity and the consequence lack of effective management of traffic, navigational channels are often grossly underutilized or highly congested. The traditional rule of first-come-first-served admission of vessels to channels is not efficient as it assumes equal time intervals between entrance of consecutive vessels. A new vessel traffic management system is developed in this research and methodologies to measure the improvement in the channel capacity are developed. Methodology to measure the channel performances for three queue disciplines are developed. The effects of changes in major factors on the channel capacity model such as channel length, fleet mix and arrival rate, as well as changes in strategy are analyzed. Under given channel conditions, best strategy are recommended. Also, a method for effective stochastic channel capacity simulation was developed. The results of analysis and as ertions are compared with the results of simulation runs to prove their applicability.

• 한국시뮬레이션학회논문지
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• 제17권4호
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• pp.1-9
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• 2008

본 논문은 Programmable Logic Controller(PLC) 시뮬레이션을 하기 위한 공장 모델(Plant Model)을 자동으로 생성하는 절차에 대해 기술한다. PLC 프로그램은 공정을 제어하는 로직에 관한 정보이며 그 자체로 공장 모델에 대한 어떤 정보도 포함하고 있지 않기 때문에 시뮬레이션을 위해서는 PLC 프로그램에 대응하는 공장 모델이 반드시 필요하다. 지금까지 PLC 시뮬레이션을 위한 공장 모델은 사용자가 직접 구축하는 방식으로 모델링 되었으나 이는 많은 노력과 공정로직의 완전한 이해 및 시뮬레이션 지식이 요구된다. 이런 어려움을 극복하기 위해 논문은 PLC 프로그램의 심볼테이블(Symbol table)로부터 공장모델을 자동으로 생성하는 과정을 제안한다. 이를 위해P LC 심볼이 공장 모델의 생성을 위한 정보를 포함시키는 PLC 심볼의 작명 규칙을 제안한다. 입력된 심볼 리스트를 분석함으로써 공장 모델을 자동으로 추출할 수 있으며 간단한 예제 공정을 대상으로 구현해 본다.