Kenneth E. Case

• Oklahoma State University

Assessment of progressive, nano-scale variation of surface morphology during ultraprecision manufacturing processes, such as fine-abrasive polishing of semiconductor wafers, is a challenging proposition owing to limitations with traditional surface quantifiers. We present an algebraic graph theoretic approach that uses graph topological invariants...

We present an algebraic graph theoretic approach for quantification of surface morphology. Using this approach, heterogeneous, multi-scaled aspects of surfaces, e.g., semiconductor wafers, are tracked from optical micrographs as opposed to reticent profile mapping techniques. Therefore, this approach can facilitate in situ real-time assessment of s...

A number of variations of facilities location problems have appeared in the research literature in the past decade. Among these are problems involving the location of multiple new facilities in a discrete solution space, with the new facilities located relative to a set of existing facilities having known locations. In this paper a number of discre...

This article is the first in a series of two articles that applies two-stage short-run control charting to (X, MR) charts. Theory is developed and then used to derive the control chart factor equations. In the sequel, the control chart factor calculations are computerized and an example is presented.

This article develops the theory that is needed to apply the two-stage short-run theory of control charting to ([Xbar], s) charts. It then uses this theory to derive the equations for calculating the factors required to determine two-stage short-run control limits for ([Xbar], s) charts. Also, equations to calculate conventional control chart const...

In their 1970 paper titled “Mean and Variance Control Chart Limits Based on a Small Number of Subgroups” (Journal of Quality Technology, Volume 2, Number 1, pp. 9–16), Yang and Hillier originally derive equations for calculating the factors required to determine two-stage short-run control limits for ( X¯, v) and ( X¯, ) charts. However, their deri...

Energy users such as industrial production plants, public service entities, hospitals, universities, and others may desire to upgrade their energy system, often including such things as HVAC, lighting, furnaces, cooling towers, etc. These energy users are referred to as “clients.” “Performance contracts” provide a unique financial arrangement betwe...

This paper is the second in a series of two papers that fully develops two-stage short-run (X, MR) control charts. This paper describes the development and execution of a computer program that accurately calculates first- and second-stage short-run control chart factors for (X, MR) charts using the equations derived in the first paper. The software...

This paper is the second in a series of two papers that fully develops two-stage short-run (X, MR) control charts. This paper describes the development and execution of a computer program that accurately calculates first- and second-stage short-run control chart factors for (X, MR) charts using the equations derived in the first paper. The software...

The effect of the biased and unbiased estimators of process standard deviation on the performance of X̄ charts is studied, with reference to false alarm rates. The false alarm rate function of X̄ charts is derived on the subgroup and the effect of the coefficients of the process standard deviation (denoted as k t) on X̄ control charts is studied. T...

In their 1970 paper titled "Mean and Variance Control Chart Limits Based on a Small Number of Subgroups" (Journal of Quality Technology, Volume 2, Number 1, pp. 9-16), Yang and Hillier originally derived equations for calculating the factors required to determine second stage short run control limits for ) v,X c( and )s ,X( c charts. Two issues hav...

This paper describes the development and execution of a computer program that will accurately calculate first- and second-stage short-run control chart factors for (X¯,v) and (X¯,√v) charts. The software used is Mathcad 8.03 Professional with the Numerical Recipes Extension Pack. Exact equations for the distributions of the variance and the student...

An effective way to ensure a high degree of statistical process control (SPC) for clinical diagnostics manufacturers is presented. Measurement variation can be controlled, resulting in effective SPC methods. Particularly, measurement variation can be controlled through blocking, leading to a relatively small amount of data collection to achieve pro...

With increased focus on reducing costs in the healthcare industry, the economic aspects of quality control for clinical laboratories must be addressed. In order to evaluate the economic performance of statistical quality control approaches used in the clinical setting, an economic model is developed. Although the economic model is applied specifica...

When monitoring analyzer performance in the clinical setting, laboratories are required to test multiple concentrations of control material on a daily basis. Because of the nature of laboratory testing, there is the potential for correlation between the concentrations of control material being monitored. Although traditional clinical quality-contro...

Organizations are under increasing pressure to satisfy customers, while continuously improving processes. Process improvement methodologies emphasize the importance of selecting performance measures that are related to customers. There is, however, the need for a methodology to progress backward from identifying customer needs to identifying key pe...

An extension of the Taguchi Loss Function (TLF) is used to model quality losses due to product degradation as a continuous cash flow function under continuous com-pounding.-As a result, the present worth of expected losses is introduced as a moans to provide a monetary evaluation of external quality losses (losses incurred by a product's user). Usi...

A test for normality is available that makes use of the fact that only for the normal distribution are the average x and the sample standard deviation s independent. Users are cautioned that the test is not sensitive to nonnormal distributions that are symmetrical. Normal probability paper is explored as a tool for use, in addition to the test, whe...

The developments presented in this paper are representative of the recent advances of quality control in continuous flow processes. Specifically, die research presented in English and Case [6] are extended to include the incorporation of ramp input disturbances to the input of a typical continuous flow process subjected to feedback control. The res...

The Zone Control Chart is applied to joint monitoring of process centering and variation based on an economic criterion. The control chart design parameters are the subgroup size, sampling interval measured in hours, width of control limits for the mean, width of control limits for the range or , and the four zone scores used on both charts. This s...

Many new approaches and applications have been developed in the area of the economic design of process control charts. This article provides a survey and brief summary of the work on economic designs published during the period from 1981 through 1991.

In the production of homogeneous products, it is often desirable to use individual samples for control chart purposes. In this situation, the moving range of two consecutive observations is correlated. This note presents expressions for calculating the correlation coefficient of the moving range of two individual measurements.

Companies are using the Malcolm Baldrige National Quality Award criteria for self-assessment, training, and networking. To help people understand them, Quality Progress is publishing a series on the 1992 criteria's seven examination categories. This sixth of seven installments looks at Category 6: Quality and Operational Results.

Batch production of homogeneous products is considered. The batch is accepted or rejected on the basis of a single measurement. The measurement is carried out at both the producer's and the customer's facility. Each measurement can result in rejection o..

This paper develops the economic design of an A'-bar chart for monitoring continuous flow processes such as those encountered in refining, chemical processing and mining. The economic model permits one to optimally select the subgroup size, the sampling interval, and the control limit width based upon an economic criterion. This economic model is t...

A set of statistical process control filters and the procedures for their employment as filters in a feedback control loop are designed. These filters are similar to the control charts applied to continuous flow processes. The statistical process control filters are evaluated for the quality of the process output given that a particular filter is u...

The most prominently used statistical process control tool is the X¯-chart. Duncan's economic model of Shewhart's original X¯-chart has established its optimal economic application for processes with a Markovian process failure mechanism. However, there are practical situations in which the distribution of the time to failure of the process is not...

Some studies have been done to construct quality control charts using the Exponentially Weighted Moving Average, EWMA. However, they have been done implicitly for subgroups of size n and individual data. Moreover, the emphasis of the control chart of the EWMA has been on the monitoring of only the process mean. Even though there are articles discus...

This paper represents a portion of the evaluation of the use of Statistical Process Control within the realm of Conventional Computer Process Control. Various control charts commonly utilized in continuous processes are evaluated when subjected to process disturbances typical of continuous processes. The control charts considered are the Moving Ave...

To help in the implementation of Lund's probability of cloud-free line-of-sight (PCFLOS) calculations (method A and method B) for limited altitudes, a methodology for cumulative cloud cover calculation (required for both methods) is introduced and a methodology for cumulative cloud form determination (required for method B) is developed. To study t...

This article deals with several items, including theoretical and applied results. Specific topics include (1) a discrete, economically based, attributes acceptance sampling model and its adaptations, (2) relevant costs, (3) relevant prior distributions, (4) comparison of single- and double-sampling results, and (5) reasons for marginal implementati...

Bayesian acceptance sampling plans, including the increasingly popular economically-based versions, require the specification of a prior distribution of defectives from lot to lot. This paper examines the relationship between defectives in the sample and defectives in the rest of the lot for each of five prior distributions. It is seen that the use...

An economic model is developed which determines the design of joint X- and R-control charts to minimize costs. The design parameters are sample size, width of X-control chart limits, width of R-control chart limits, and sampling interval in hours. Duncan's approach to the economic design of control charts is used. The control states permitted are t...

Nine different sample/rest-of-lot disposition policies for single and double sampling, along with explicitly developed AOQ and ATI expressions for each—both with and without inspection error— are considered. The nine dispositions include all combinations of scrapping/eliminating defectives/replacing defectives in the sample and scrapping/eliminatin...

Two modeling techniques for simulating availability are developed. A technique is developed for introducing multiple operating conditions into simulation models. Another technique is developed for incorporating an operating-time adjustment for repair in availability simulations. A general operating-time adjustment-technique is developed and then tw...

Independent researchers and practitioners have conclusively shown that inspectors make mistakes, classifying bad items as good and vice versa. This paper mathematically and graphically examines the effects of inspection error on the p chart. The point of view that control limits are based upon a target value, and the point of view that control limi...

A mathematical model is developed for a quality control system for variables where the decision criteria may call for lot acceptance, lot screening, or lot scrapping. Since application of the quality control system may lead to one of three results, the model is termed three action. Exact and approximate conditions for optimality are developed. Cond...

This paper describes an interactively programmed computer tool with wide ranging capability for sampling plan design and evaluation. Developed under sponsorship of the National Science Foundation, this tool is useful in sampling plan optimization, evaluation, and simulation of inspection activities. It has both a statistical and an economic base, a...

In a recent presentation [1], the authors described an Industrial Engineering Systems study of a large scale refuse collection-disposal-recycling-energy reclamation system that had produced substantial savings for a large concern in metropolitan Washington, DC. In the study, it was necessary to develop a cost model applicable to the collection and...

Inspection error has clearly been shown to have adverse effects upon the results desired from a quality assurance sampling plan. These effects upon performance measures have been well documented from a statistical point of view. However, little work has been presented to convince the QC manager of the unfavorable cost consequences resulting from in...

Sequential sampling represents the logical limit in lot-by-lot multiple acceptance sampling. Sequential plans are generally developed in order to fit a desired operating characteristic curve. The basic premise is that items are observed one at a time and classified as good or bad. Following each sampled item, and based upon the current cumulative r...

Considerable attention to the economics of variables acceptance sampling has recently emphasized that the alpha-beta approach to sampling plan design may be far from optimal. Similarly, recent results conclusively show that measurement error manifested as bias (inaccuracy) and imprecision (variability) can have disastrous effects upon the OC curve...

The Type B Operating Characteristic curve in attributes acceptance sampling is simply the probability of lot acceptance versus process fraction defective. The binomial mass function is appropriate for assessing this acceptance probability. Articles on inspection error in attributes acceptance sampling frequently assume the marginal distribution of...

A mathematical model for multiattribute acceptance sampling is developed. The number of defectives of each attribute in the lot is considered an independent random variable and is properly described by a discrete prior mass function. The concept of distributional reproducibility to hypergeometric sampling is invoked to simplify the expressions norm...

Variables acceptance sampling plans are designed under the assumption that measurement on the characteristic of interest may be performed without error. To the contrary, variables measurement tasks are often confounded by human inspection error and/or instrument test error. The net result may be characterized in terms of bias and imprecision, where...

This paper develops and provides formulas for calculating the Average Outgoing Quality (AOQ) when attributes examination is subject to Type I and Type II inspection errors. Nine different rectification inspection policies are considered. Each AOQ expression is evaluated using a typical sampling plan and the results are presented graphically for fou...

In this paper the effects of inspector error on a cost-based quality control system are investigated. The system examined is of a single sampling plan design involving several cost components. Both type I and type II inspector errors are considered. The model employs a process distribution, thus assuming that a stochastic process of some kind gover...

In this paper two total cost models are presented for acceptance sampling by variables. The first model is for the case where rejected lots are screened and the second for scrapping of rejected lots. Conditions for optimal sampling plan development are presented for both models and illustrated by example. In addition, the sensitivity of both models...

This paper examines the results of Dodge's CSP-1 continuous sampling plan under inspection error. Both type I and II errors are explicitly included. Their effect on the average number of items inspected in a 100% screening sequence, average number of items passed during sampling inspection, average fraction of items inspected, proportion of items p...

Acceptance sampling plans are designed under the assumption of perfect inspection. However, inspection tasks are not, even under ideal inspection conditions, free of error. In this paper we consider the effects of inspection error on probability of acceptance, average outgoing quality, and average total inspection. These measures are examined under...

The computation of reliability becomes quite tedious when one has to deal with a non series-parallel system. In this paper a proposed method is developed by taking the system as a probabilistic graph in which a component of the system is represented by a branch. The proposed method is composed of three phases: Phase 1 involves the reduction of all...

Engineering companies are frequently requested to submit a fixed-price bid or a ceiling on cost-plus bids. These bids may be subjected to competition or negotiations. In order to determine the bid price, engineering management must first estimate the actual costs to be incurred on the project. The method presented utilizes three estimates for each...

The problem treated is that of determining the minimum cost distribution system for supplying water to several demand centers having demand patterns which change over time. The costs of the system are taken to be functions of the lengths of alternative pipe sizes used, as well as the friction losses produced by the flow of water. The decision varia...

A model was developed to analyze the long-term effect of the addition of a spring gobbler hunt on the dynamics of a hypothetical population of eastern wild turkeys (Meleagris gallopavo silvestris) already subjected to a fall hunt of either sex. The random variables-the total annual mortality rate, the hunting mortality rate, and the immature:adult...

In their 1970 paper titled "Mean and Variance Control Chart Limits Based on a Small Number of Subgroups" (Journal of Quality Technology, Volume 2, Number 1, pp. 9-16), Yang and Hillier originally derived equations for calculating the factors required to determine second stage short run control limits for) v , X c (and) s , X (c charts. Two issues h...

Techniques for determining aggregate parts quantities needed over production planning horizons are well developed. However, proper recognition of the inherent process quality capabilities are not well developed. This paper develops and discusses mathematical techniques for increasing upstage production levels to recognize the losses resulting from...

Following is the continuation of the list of titles and authors of the papers presented: Economic Design of a Dual Purpose Multicharacteristic Quality Control System. By Barry A. Latimer, G. Kemble Bennett and J. W. Schmidt. Experiment in Continuing Education. By C. Robert Emerson and William R. Taylor. Statewide Allocation System for Improved Cons...

Traducción de: Principles of Engineering Economic Analysis Texto sobre los principios de análisis de alternativas económicas de inversión. Contiene: Introducción; Conceptos sobre los costos; Operaciones de valor del dinero en el tiempo; Comparación de alternativas; Consideraciones acerca de la depreciación y los impuestos sobre la renta; Análisis d...