• 대한안전경영과학회지
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• 제9권2호
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• pp.123-134
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• 2007

This paper focuses on the in-house reliability assurance plan for the bulk materials of each company. The reliability assurance needs in essence a long time and high cost for testing the materials. In order to reduce the time and cost, accelerated life test is adopted. The bulk sampling technique was used for acceptance. Design parameters might be total sample size(segments and increments}, stress level and so on. We focus on deciding the sample size by minimizing the asymptotic variance of test statistics as well as satisfying the consumer's risk. In bulk sampling, we also induce the sample size by adapting the normal life time distribution model when the variable of the lognormal life time distribution is transformed and adapted to the model. In addition, the sample size for both the segments and increments can be induced by minimizing the asymptotic variance of test statistics of the segments and increments with consumer's risk met. We can assure the reliability of the mean life and B100p life time of the bulk materials by using the calculated minimum sample size.

• 품질경영학회지
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• 제25권3호
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• pp.22-38
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• 1997

In a traditional sequential acceptance sampling plan, it is assumed that the sampled items are independent each other. In this paper, stochastically dependent sequential acceptance sampling plans are dealt when there exists dependency between sampled items. Monte-Calro algorithm is used to find the acceptance and rejection probabilities of a lot. The number of defectives for the test to be accepted and rejected in probability ratio sequential test can be found by using these probabilities. The formula for measures of performance of these sampling plans is developed. Type I and II error probabilities are estimated by simulation. This research can be a, pp.ied to sequential sampling procedures in place of control charts where there is a recognized and necessary dependency during the production processes. Also, dependent multiple acceptance sampling plans can be derived by extending this sequential sampling procedure. As a numerical example, a Markov dependent process model is given, and the characteristics of the sampling plans are examined according to the change of the dependency factor.

• 산업기술연구
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• 제1권
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• pp.67-71
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• 1981

The sequential sampling models are presented in a form which includes inspector error. The effect of inspector errors on the probability of type I and type II errors is discussed.

• 대한산업공학회지
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• 제28권4호
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• pp.351-359
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• 2002

In this paper, stochastically dependent single and sequential acceptance sampling plans are dealt when the process follows a Polya process model. A Monte-Cairo algorithm is used to find the acceptance and rejection probabilities of a lot. The number of defectives for the test to be accepted and rejected in a probability ratio sequential test can be found by using these probabilities. The formula to measure performance of these sampling plans is developed. Type I and II error probabilities are estimated by simulation. Dependent multiple acceptance sampling plans can be derived by extending the sequential sampling procedure. In numerical examples, single and sequential sampling plans of a Polya dependent process are examined and the characteristics are compared according to the change of the dependency factor.

• 한국임상수의학회지
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• 제29권1호
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• pp.58-62
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• 2012

To protect aquatic animal health of importing countries from the potential risks associated with exotic diseases introduced through international trade of live aquatic animals, inspection of designated commodities at ports of entry is a critical component of the safeguarding system. The only way to be 100% confident that no fishes in a shipment are infected with a specific agent is to test every fish in the commodity imported with a perfect diagnostic test. For the majority of cases, this is unrealistic since the group of interest may very large particularly for aquatic animals, or imperfect tests are often available. It is, therefore, more common to test a fixed proportion of a group by preplanned sampling schemes. However, decision making based on results of testing the sample can provide quite a chance that infected groups may be misclassified as uninfected, depending on sampling strategy employed. The objective of this study was to determine the possibility that one or more fishes in the group imported being infected but tests negative after inspecting samples. This question is critical to government authorities to examine whether sampling plan is sufficient to achieve the purpose intended for. At fixed population size, the maximum number of infected fishes when all tests negative was decreased as the sampling fraction increased. The probability of including at least one undetected but infected fish in a group for negative tests increased with the number of fish tested or true prevalence. The risk was much lesser where high sensitivity test was assumed; when increasing test sensitivity from 0.9 to 0.99, this risk was dramatically reduced to about a tenth or a fourth for prevalence ranges from 2 to 10%, given sample size ranges from 10 to 200. Based on the preliminary analysis, the author concluded that current sampling plan testing 4-8% of the import proposal for human consumption still can yield high false negative results. Therefore, from the quarantine inspection point of view, an enforced commodity-specific sampling design that accounts for the cost of testing with an imperfect test at the specified design prevalence is urgent.

• 대한산업공학회지
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• 제23권4호
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• pp.793-802
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• 1997

A sampling plan is presented for situations where sampling inspection is based on the quality characteristic of interest and items in rejected lots are screened based on a correlated variable. A cost model is constructed which involves the costs of misclassification errors, sampling and screening inspections. A method of finding optimal values of sample size, acceptance number and cutoff value on the correlated variable is presented, and numerical studies are given.

• Communications for Statistical Applications and Methods
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• 제6권1호
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• pp.143-150
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• 1999

Ko(1998) proposed a procedure to enhance the efficiency of double sampling plans by allowing second-stage sample size and critical region to depend on first-stage evidence using constraint optimization approaches. In this study further developments of such plans by incorporating several practically possible researcher's aims into the optimization are considered. Comparisons are made with the optimal ordinary double sampling plan and also among them It is observed that it is to some extent possible to match the details of the optimization to certain qualitative methodological aims.

• 산업경영시스템학회지
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• 제23권59호
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• pp.97-103
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• 2000

This study considers the design of life test sampling inspection plans by attributes for failure rate level qualification at selected confidence level. The lifetime distribution of products is assumed to be exponential. MIL-STD-690C and KS 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 expected cost model considering product cost, capability, environmental test cost, etc.

• 품질경영학회지
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• 제29권1호
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• pp.113-127
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• 2001

Skip-lot sampling plans for lot-by-lot inspection are more desirable than the continuous sampling plans for units in modern mass production system under the condition of the submitted product is good. Perry(1973a, 1973b) extended the Dodge(1955)′s skip-lot sampling plans to single and two-level skip-lot sampling plans and Parker & Kessler (1981) modified Perry(1973a)′s plans so that a sample of size one is taken from every lot skipped during the skipping mode. In this paper, Perry(1973b)′s two-level skip-lot sampling plans are modified by applying Parker & Kessler′s plan, designated as MTSkSP1, MTSkSP2, MTSkSP3. Operating characteristic(OC) functions, average sample numbers(ASN) and average outgoing qualities(AOQ) for the proposed plans are derived using Markov chain properties and compared each other and Perry′s plans. The proposed plans not only reduce the ASN but also avoid the danger skipping lots entirely when the lots are produced during sudden "out-of-control".

• 산업진흥연구
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• 제8권1호
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• pp.111-117
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• 2023

품질관리를 위한 샘플링검사 방식은 산업계에서 많이 제안되어왔다. 하지만 시간을 염두에 둔 품질인 신뢰성에 대한 샘플링검사 방식은 상대적으로 덜 제시되었으며, 일목요연하게 요약한 문헌도 그리 많지 않은 편이다. 이에 여기에서는 신뢰성 시험 중 대상 제품의 신뢰성 평가척도값이 목표로 하는 값을 만족하는지 확인하기 위한 신뢰성 적합시험의 설계에 대하여 설명한다. 이를 위해 먼저 소비자와 생산자가 모두 만족할 수 있는 조건은 무엇인지 OC곡선의 측면에서 살펴보면서 원하는 수준의 생산자위험과 소비지위험을 만족하는 샘플링검사가 무엇인지 알아본다. 이어서 신뢰성 샘플링검사 방식은 계수형과 계량형의 두 가지 방식이 있으므로 이들에 대해 살펴본다. 구체적으로 계수형 신뢰성 샘플링검사 방식은 대상 제품 중 n개의 시험품을 샘플링하여 일정 기간인 T시간 동안 시험하여 고장발생수가 c개 이하이면 합격시키는 형태이고, 계량형 신뢰성 샘플링검사 방식은 n개의 시험품을 미리 정한 기준의 시험시간 동안 시험하여 얻어진 시험 데이터를 이용하여 MTBF와 같은 신뢰성 평가척도값을 계산한 후 이 값이 일정 기준을 만족하면 합격시키는 형태이다. 계수형이든 계량형 신뢰성 샘플링검사이든 검사표를 이용할 수도 있다.