• Title, Summary, Keyword: Sampling plan

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A Sampling Inspection Plan with Human Error: Considering the Relationship between Visual Inspection Time and Human Error Rate

  • Lee, Yong-Hwa;Hong, Seung-Kweon
    • Journal of the Ergonomics Society of Korea
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    • v.30 no.5
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    • pp.645-650
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    • 2011
  • Objective: The aim of this study is to design a sampling inspection plan with human error which is changing according to inspection time. Background: Typical sampling inspection plans have been established typically based on an assumption of the perfect inspection without human error. However, most of all inspection tasks include human errors in the process of inspection. Therefore, a sampling inspection plan should be designed with consideration of imperfect inspection. Method: A model for single sampling inspection plans were proposed for the cases that visual inspection error rate is changing according to inspection time. Additionally, a sampling inspection plan for an optimal inspection time was proposed. In order to show an applied example of the proposed model, an experiment for visual inspection task was performed and the inspection error rates were measured according to the inspection time. Results: Inspection error rates changed according to inspection time. The inspection error rate could be reflected on the single sampling inspection plans for attribute. In particular, inspection error rate in an optimal inspection time may be used for a reasonable single sampling plan in a practical view. Conclusion: Human error rate in inspection tasks should be reflected on typical single sampling inspection plans. A sampling inspection plan with consideration of human error requires more sampling number than a typical sampling plan with perfect inspection. Application: The result of this research may help to determine more practical sampling inspection plan rather than typical one.

Optimal designing of skip lot sampling plan of type SkSP-2 with double sampling plan as the reference plan under generalized exponential distribution

  • Suresh, K.K.;Kavithamani, M.
    • International Journal of Reliability and Applications
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    • v.15 no.2
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    • pp.77-84
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    • 2014
  • In this paper, a optimal designing methodology is proposed to determine the parameters for skip-lot sampling plan of type SkSP-2 plan with double sampling plan as reference plan, when the lifetime of the product follows generalized exponential distribution. The two points on the operating characteristic curve approach are used to find the optimal parameters for the proposed plan. The plan parameters are determined so as to minimize the average sample number subject to satisfying simultaneously both producer and consumer risks at the acceptable and limiting quality levels respectively.

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A Study of Dependent Nonstationary Multiple Sampling Plans (종속적 비평형 다중표본 계획법의 연구)

  • 김원경
    • Journal of the Korea Society for Simulation
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    • v.9 no.2
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    • pp.75-87
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    • 2000
  • In this paper, nonstationary multiple sampling plans are discussed which are difficult to solve by analytical method when there exists dependency between the sample data. The initial solution is found by the sequential sampling plan using the sequential probability ration test. The number of acceptance and rejection in each step of the multiple sampling plan are found by grouping the sequential sampling plan's solution initially. The optimal multiple sampling plans are found by simulation. Four search methods are developed U and the optimum sampling plans satisfying the Type I and Type ll error probabilities. The performance of the sampling plans is measured and their algorithms are also shown. To consider the nonstationary property of the dependent sampling plan, simulation method is used for finding the lot rejection and acceptance probability function. As a numerical example Markov chain model is inspected. Effects of the dependency factor and search methods are compared to analyze the sampling results by changing their parameters.

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Hybrid Group-Sequential Conditional-Bayes Approaches to the Double Sampling Plans

  • Seong-gon Ko
    • Communications for Statistical Applications and Methods
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    • v.5 no.1
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    • pp.107-120
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    • 1998
  • This research aims here to develop a certain extended double sampling plan, EDS, which is an extension of ordinary double sampling plan in the sense that the second-stage sampling effort and second-stage critical value are allowed to depend on the point at which the first-stage continuation region is traversed. For purpose of comparison, single sampling plan, optimal ordinary double sampling plan(ODS) and sequential probability ratio test are considered with the same overall error rates, respectively. It is observed that the EDS idea allows less sampling effort than the optimal ODS.

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Operating Characteristic Properties of Two Types of Multi-Level Skip-Lot Sampling Plans

  • Byoung-Chul Choi
    • Communications for Statistical Applications and Methods
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    • v.2 no.2
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    • pp.358-365
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    • 1995
  • This paper presents another system of multi-level skip-lot sampling plan, which can directly retum to normal inspection from any skpping inspection level when a sudden shift for the worse in the process mean occurs. All the other properties of the proposed sampling plan are similar to those of the Choi's(1993) plan. The formula of the poerating characteristic function for the proposed n-level skip-lot sampling plan is derived. Sone poerating characteristic properties for the proposed plan are graphically compared with those of the Choi's plan.

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A Study on the Rectifying Inspection Plan & Life Test Sampling Plan Considering Cost (소비자 보호를 위한 선별형 샘플링 검사와 신뢰성 샘플링 검사의 최적설계에 관한 연구)

  • 강보철;조재립
    • Journal of the Korean Society for Quality Management
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    • v.30 no.1
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    • pp.74-96
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    • 2002
  • The objectives of this study is to suggest the rectifying sampling inspection plan considering quality cost. Limiting quality level(LQL) plans(also called LTPD plans) and outgoing quality(OQ) plans are considered. The Hald's linear cost model is discussed with and without a beta prior for the distribution of the fraction of nonconforming items in a lot. It is assumed that the sampling inspection is error free. We consider the design of reliability acceptance sampling plan (RASP) for failure rate level qualification at selected confidence level. The lifetime distribution of products is assumed to be exponential. MIL-STD-690C and K C 6032 standards provide this procedures. But these procedures have some questions to apply in the field. The cost of test and confidence level(1-$\beta$ risk) are the problem between supplier and user. So, we suggest that the optimal life test sampling inspection plans using simple linear cost model considering product cost, capability of environment chamber, environmental test cost, and etc. Especially, we consider a reliability of lots that contain some nonconforming items. In this case we assumed that a nonconforming item fail after environmental life test. Finally, we develope the algorithm of the optimal sampling inspection plan based on minimum costs for rectifying inspection and RASP. And computer application programs are developed So, it is shown how the desired sampling plan can be easily found.

A Study on the Economical Design of Sampling Plan for Rectifying Inspection by Attribute (계수(計數) 선별형검사(選別型檢査) 설계(設計)의 경제성(經濟性)에 관한 연구(硏究))

  • Kim, Yun-Seon;Hwang, Ui-Cheol
    • Journal of the Korean Society for Quality Management
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    • v.9 no.1
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    • pp.40-45
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    • 1981
  • This paper deals with an economical sampling plan, recently being concentrated on and, namely, investigates how to determine the basic concepts to settle the sampling plan of a minimum cost. On an inspection of sampling, a Linear Cost Model of a cost function which is concerned with the representative cost dements, is established and by the investigation of its possible solution economical single sampling plan for recitying inspection by attribute is suggested.

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On the Estimation of Fraction Defectives

  • Kim, Seong-in
    • Journal of the Korean Society for Quality Management
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    • v.8 no.2
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    • pp.3-14
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    • 1980
  • This paper is concerned with the design of an appropriate sampling plan or stopping rule and the construction of estimate for the estimation of process or lot fraction defective. Various sampling plans which are well known or have potential applications are unified into a generalized sampling plan. Under this sampling plan sufficient statistic, probability distribution, moment, and minimum variance unbiased estimate are obtained. Results for various sampling plans can be derived as special cases. Then, under given parameter values, the relative efficiencies of the various sampling plans are compared with respect to expected sample sizes and variances of estimates.

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Sampling Plans Based on Truncated Life Test for a Generalized Inverted Exponential Distribution

  • Singh, Sukhdev;Tripathi, Yogesh Mani;Jun, Chi-Hyuck
    • Industrial Engineering and Management Systems
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    • v.14 no.2
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    • pp.183-195
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    • 2015
  • In this paper, we propose a two-stage group acceptance sampling plan for generalized inverted exponential distribution under truncated life test. Median life is considered as a quality parameter. Design parameters are obtained to ensure that true median life is longer than a given specified life at certain level of consumer's risk and producer's risk. We also explore situations under which design parameters based on median lifetime can be used for other percentile points. Tables and specific examples are reported to explain the proposed plans. Finally a real data set is analyzed to implement the plans in practical situations and some suggestions are given.

Tightened-Normal-Tightened Group Acceptance Sampling Plan for Assuring Percentile Life

  • Aslam, Muhammad;Azam, Muhammad;Jun, Chi-Hyuck
    • Industrial Engineering and Management Systems
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    • v.11 no.4
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    • pp.390-396
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    • 2012
  • The present paper extends the idea of tightened-normal-tightened sampling scheme to group acceptance sampling plans under the time truncated life tests. We consider three famous distributions that are widely used in the area of reliability such as the generalized exponential distribution, the Weibull distribution, and the Birnbaum-Saunders distribution in the proposed sampling plan. The plan parameters are determined such that the producer's risk and the consumer's risk are satisfied at the specified median life. Extensive tables showing plan parameters are provided at various values of the experiment time and the consumer's risk for each of three distributions for the practical use. Some examples are given to illustrate the procedure of the proposed plan.