• Journal of Korean Society for Quality Management
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• v.18 no.1
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• pp.1-8
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• 1990

In this paper we present a procedure to determine the quantity of incoming materials when the nonconforming materials appear in the production process. We determined the total loss of materials $D_2$ due to fraction defectives in process and added this $D_2$ to the quantity of incoming materials $Q_0$ considered ingoing-outgoing quality level. The quantity of materials $Q_1$ as a result of this procedure should be an economic purchasing quantity and is a rectifying quantity of the EOQ determined in classical inventory model.

• Journal of Korean Society for Quality Management
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• v.20 no.2
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• pp.55-66
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• 1992

The sampling plan CSP-1 for continuous production was first proposed by Dodge in 1943. Continuous production refers to products which are flowing past the inspection station such as products moving on a conveyor belt. One important measure of the effectiveness of a CSP is the average outgoing quality(AOQ). A concept for a short run of production length time, denoted by AOQ(t), is provided. The assumption of a s-independence in CSP-1 is unrealistic. It is possible to relax the assumption of a s-independence. The need for Markov model in a continuous production process can be discussed in this paper. The Markov and renewal theory are used to describe the property of AOQ in CSP-1.

• Journal of Korean Society for Quality Management
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• v.27 no.1
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• pp.35-45
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• 1999

A process monitoring procedure using a correlated variable is presented when a lower specification limit is given on the performance variable. Every item is inspected with a variable correlated with the performance variable. When an item is rejected in the screening inspection, the process is checked for change using the mean and variance of measurements of the correlated variable for n preceding items including the rejected one. The performance variable is assumed to be normally distributed. A linear relationship between the performance and surrogate variables is assumed with normally distributed error term. The monitoring procedure is designed so that the prespecified outgoing quality can be attained.

• Journal of the Korea Safety Management & Science
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• v.11 no.1
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• pp.115-120
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• 2009

Single PPM Quality Innovation Movement is originally developed quality program in Korea for supplier's quality level-up since 1995. The quality target is below the 10ppm(parts per million) in outgoing quality and delivered goods plus field claim. This Single PPM Quality Innovation Movement program was conducted to realize the anticipated results not only due to management result level's increasing, but also the company's confidence and competitiveness. This study attempted to find the mutual influences on the participation of the constituent members, satisfaction of the constituent members and results of the management from Single PPM Quality Innovation Movement. The reliance analysis for the measurement material on the questionnaire was verified by Cronbach's alpha coefficient. Participation of the constituent members, satisfaction of the constituent member and result of the management, the influences upon Single PPM improvement degree level were verified through the structural analysis by using SPSS statistic package. The influence evaluation among the groups was evaluated by the structure equation.

• Industrial Engineering and Management Systems
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• v.8 no.3
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• pp.131-138
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• 2009

The variable sampling inspection scheme with screening for the purpose of assuring the upper limit of maximum expected surplus loss after inspection has been proposed. In this inspection scheme, it has been assumed that a product lot consists of products manufactured through a single production line and lot quality characteristics follow a normal distribution. In the previous literature with respect to inspection schemes, it has been commonly assumed that lot quality characteristics obey a single normal distribution under the condition that all products are manufactured in the same condition. On the other hand, the production line is designed in order that the workload of respective processes becomes uniform from the viewpoint of line balancing. One of the solutions for the bottleneck process is to arrange the workshops in parallel. The lot quality characteristics from such a production line with the process consisting of some parallel workshops might not follow strictly the single normal distribution. Therefore, we expand an applicable scope of the above mentioned variable sampling inspection scheme with screening in this article. Concretely, we consider the variable sampling inspection with screening for the purpose of assuring the upper limit of average outgoing surplus quality loss in the production lots when the lot quality follows the mixed normal distribution.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.365-368
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• 2006

The implementation of a screening procedure for removing non-conforming products has become a common practice especially in high-tech manufacturing industries. Screening procedures involve a measurement on the quality characteristic of interest since decisions regarding the conformance to specifications are usually made on the basis of the realization of measurement. A significant variability in measurement procedures may result in the misclassification of an outgoing product (that is, falsely accepting defectives or falsely rejecting conforming items), which may lead to wrong interpretation on product quality, It may thus be necessary to consider the impacts of misclassification errors due to measurement variability when designing screening procedures. Along this line, this article investigates the design of screening procedures based on the assessment of misclassification errors. The main objective is to determine the screening limits on measured values so that two types of misclassification errors may properly be compromised.

• Journal of Korean Society for Quality Management
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• v.29 no.1
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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".

• Journal of Korean Society for Quality Management
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• v.35 no.4
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• pp.147-158
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• 2007

Owing to the rapid growth in automated manufacturing systems, screening inspection becomes an attractive practice for removing nonconforming items, and it has been suggested that inspection will essentially become an inherent part of modem manufacturing processes. In this paper, we propose rectifying screening inspections which allow quality practitioners to use performance and surrogate variables interchangeably in real-time applications. Two screening inspections are considered; a statistically-based screening inspection to reduce the current proportion of nonconforming items to a specified AOQ(average outgoing quality) after screening, and an economically-based screening inspection where the tolerance limit is determined so that the expected total cost is minimized. It is assumed that the performance variable and the surrogate variable are jointly normally distributed. For two screening inspections, methods of finding the optimal solutions are presented and numerical examples are also given.

• Journal of the Korea Safety Management & Science
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• v.11 no.3
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• pp.199-207
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• 2009

IP Telephony service was restricted to an outgoing call and low quality since the trust domestic IP Telephony service launch of Saerome co. Ltd, in Jan. 2000. However, Interest of IP Telephony service, which is substituted for PSTN, has been highly elated because of the developed equipment softswitch and new technology. This kind of importance and marketing of VoIP are recognized to telecommunication providers. With this trend, they try to administrate customer satisfaction and invest R&D to survive in this hard competition and unexpected change. To achieve this objective, they should try to realize the searching process of the quality decision attribution (QDA). However, there is little research on the aspect of service quality of Internet telephony so far. For this, the investigator established the tangibles, the reliability, the responsibility, the assurance, the empathy, the charge with information sources as core elements. In order to examine the influence of IP Telephony service upon the attitudes toward a brand and the purchase intention.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.1
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• pp.123-140
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• 1997

In this paper we consider closed flow line systems with samploing inspections. The total number of parts in the system is assumed to be N. The processings carried out of each station do not always meet the requirement of quality. Therefore, upon completion of its processing at each station, a part is inspected to determine whether the processings meet the requirement of quality or not. We assume that inspection are done on a random basis. If a part is found to be defective by an inspection, it is fed back to the apropriate station. Two different cases will be considered in this study : a three-station flow line system with infinite buffers and a two-station flow line system with finite buffers. For each case, we will develop an exact method to obtain the performance measures such as throughput, machinen utilization, average outgoing quality and manufacturing lead time. For the case of the two-station flow line system ith finite buffers, we will also develop an approximation method using a stage-aggregation technique. Then using buffers, we will also develop an approximation method using a stage-aggregation technique. Then using these results, we will try to find an optimal inspection policy which maximizes the expected net profit under a certain cost structure. Although we present the results only for the two or three station flow line system in this paper, the results obtained in this paper can be extended easily to the system which consists of more than two or three stations.