• Title/Summary/Keyword: Inspection by attributes

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A Case Study on the Change of Sampling inspection method for the Small Depth Charge Fuze (소형폭뢰용 수압식 신관의 품질검사방법 전환사례 연구)

  • Jee, Jae-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.531-538
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    • 2017
  • In the case of hydraulic pressure type fuse, we accept or reject certain product lots by considering the number of defective products in the operating pressure test. Generally, this procedure, known as 'The inspection by attributes', has been most commonly used in the field of quality assurance of products. However, the method of inspection by attributes suffers because it tests more samples than inspection by variables. Even though the quality of the products has remained stable in the process condition, the same number of samples is required for every lot, which wastes time and money. This paper suggests that the lot acceptance procedure is changed from inspection by attributes to inspection by variables. We can calculate the statistical tolerance percent of defectives and compare this to the Acceptable Quality Level (AQL) in order to save money and time. It is also easier to monitor and control the quality of products by using the process capability index and x-bar charts. In conclusion, the procedure delivers mutual benefit to both the customer and the producer by securing high quality products and reference data.

Rectifying Inspection Plan for KS A 3102 with Gamma-Prior Distribution (Gamma-Prior가 고려된 KS A 3102의 수정검사방식(修正檢査方式))

  • Jeong, Yeong-Bae;Hwang, Ui-Cheol
    • Journal of Korean Society for Quality Management
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    • v.15 no.2
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    • pp.55-60
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    • 1987
  • A rectifying inspection plan which assumes a gamma - prior distribution on the lot percent defective is considered. This sampling inspection plan is developed for finite lot sizes with matching OC curves and generated from an initial plan selected from KS A 3102 single sampling by attributes. Comparisons are made with each plan by three examples.

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The Performance of An Inspection System Providing 3D Spatial Proximity Data and Its' Design Considerations (3차원 근접정보를 이용한 검사시스템의 성능평가와 디자인 고려사항)

  • Jeong, Gyeong-Ho
    • Journal of the Ergonomics Society of Korea
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    • v.23 no.1
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    • pp.13-22
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    • 2004
  • Due to economical or technological reasons. humans are responsible for inspection functions in many cases. Humans. however. are rarely perfect. thus allowing non-confirming parts to be processed. As the attributes of interest or the variety of products increases. the inspection system becomes less effective because of the sensory and cognitive limitations of human inspectors. Any means that can support or aid the human inspectors is necessary to compensate for inspection difficulty. Augmented reality (AR) offers a new approach in designing an inspection system as a means to augment the cognitive capability of inspectors by providing the 3D spatial proximity between two information channels. The experimental results suggest that AR might be an effective tool that reduces inspection time without sacrificing the measuring accuracy.

Rectifying inspection for single sampling by attributes with lot size N and prior distribution of p (불량률의 사전분포와 로트크기를 고려한 계수규준형 샘플링 검사의 수정 검사방식)

  • 이도경;이근희
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.12 no.20
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    • pp.77-80
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    • 1989
  • A rectifying sampling plan which assumes a prior distribution on the lot percent defective is considered. This sampling is developed for finite lot size N with matching OC curves and generated from an initial plan selected from single sampling by attributes.

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A study on equilibrium of the amount of requisite materials and purchasing materials considering the fraction defective of the lot (로트불량율을 고려한 자재소요량과 자재구입량의 균형화 연구)

  • 이회식
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.9 no.13
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    • pp.13-16
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    • 1986
  • In this paper we study the decision rule for the amount of purchasing materials according to the fraction defective in the single sampling inspection by attributes based on operating characteristics. In deciding the amount of purchasing materials, it is important that we ought to occupy the practical purchasing amount, considering the fraction defective of the lot in acceptance inspection, because the acceptance probability is variant with the fraction defective of the lot.

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The Study on the Failure Rate Sampling Plan Considering Cost (비용을 고려한 신뢰성 샘플링검사 설계에 관한 연구)

  • 조재립
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.23 no.59
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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.

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A Study on the Conformity of KS Standards according to Agreement on WTO/TBT (WTO/TBT 협정에 따른 KS 규격의 부합화에 관한 연구)

  • 김진규
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.26 no.4
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    • pp.12-22
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    • 2003
  • The purposes of this study are to investigate the conformity of Korean Standards(KS) according to agreement on WTO/TBT, and to propose systematic frameworks of preparation, adoption, and application for KS in our enterprises. Significant changes in this establishment, revision, and abrogation include the following divisions; i) statistics-vocabulary and symbols, ii) Shewhart control chart, iii) statistical interpretation of data, iv) sampling procedures for inspection by attributes, v) sequential sampling plans for inspection.

ISO 2859-1 (1989), Sampling Plans Indexed by Acceptable Quality Level for Lot-by-Lot Inspection (ISO 2859-1 (1989), 계수조정형 샘플링 검사규격)

  • Hong, Sung-Hoon;Lee, Seung-Hwan
    • Journal of Korean Society for Quality Management
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    • v.24 no.3
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    • pp.77-93
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    • 1996
  • This paper is concerned with the International Standard ISO 2859-1 (1989), Sampling Plans Indexed by Acceptable Quality Level (AQL) for Lot-by-Lot Inspection, his standard is AQL type sampling scheme, and incorporates switching rules to move among normal, tightened, and reduced inspections. Sample size code letters and inspection levels of ISO 2859-1 are the same as those of other attributes standards MIL-STD-105D, ANSI Z1.4, and KS A 3109. But ISO 2859-1 has more simple switching rules than KS A 3109 has. The sampling procedures of the ISO 2859-1 are matched to the variables international standard ISO 3951 to enable us to move between them. Composite OC and ASN curves are given for AQL 2.5% and code letter F.

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ISO 3951, Sampling Procedures and Charts for Inspection by Variables for Percent Nonconforming (ISO 3951, 계량조정형 샘플링 검사규격)

  • Hong, Sung-Hoon;Lee, Seung-Hwan
    • Journal of Korean Society for Quality Management
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    • v.23 no.1
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    • pp.1-14
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    • 1995
  • ISO 3951 (1989) Sampling Procedures and Charts for Inspection by Variables for Percent Nonconforming is an acceptable quality level (AQL) type sampling scheme. Sample size code letters and inspection levels in this International Standard correspond to those given in the ISO 2859 (1989), a standard for sampling plans by attributes. Two acceptance sampling procedures can be used ; tabular and graphical methods. The graphs could be used in less critical applications while the tabular method would be available for those familiar with MIL-STD-414 tables and to confirm the results of the graphs when needed. The sampling procedures of the ISO 3951 are matched to the ISO 2859 to enable us to move between them. Composite OC and ASN curves are given for AQL 2.5% and code letter F.

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