• Title/Summary/Keyword: ARL comparisons

Search Result 6, Processing Time 0.024 seconds

A Study on Evaluation of Korean Collection of North America: Focused on the A University (북미 대학의 한국학 장서 평가에 관한 연구: A 대학을 중심으로)

  • Oh, Kyung-Mook
    • Journal of the Korean Society for information Management
    • /
    • v.25 no.4
    • /
    • pp.269-281
    • /
    • 2008
  • This paper evaluated the collection development of the Korean collection at the A university over the several decade. Compared against the ACRL standard Formula A, the result demonstrated that the Korean library collection is still needed to increase Korean collection to support Korean-related program and Korean community in the area. When we share western language materials in the library as the same area studies resources, we can evaluate Korean studies collection as Level B. Comparison with similar institutions (ARL comparisons) shows that the collection is the middle among 15 universities which provide Korean programs. The situation for Korean resources at the A university is needed to get more support from Korean institutes and Korean societies to keep up with the Korean collection for academics and regional community users as well.

Comparisons of Control Charts for Failure Rate with Fixed Inspection Interval

  • Lee, Jae-Man;Chang, Duk-Joon
    • Journal of the Korean Data and Information Science Society
    • /
    • v.15 no.4
    • /
    • pp.793-801
    • /
    • 2004
  • In this paper, we propose control charts for failure rate using the number of failures based on the fixed interval inspection with replacement. And we investigate the power of detection of the proposed control charts by the ARL.

  • PDF

Comparisons of Multivariate Quality Control Charts by the Use of Various Correlation Structures

  • Choi, Sung-Woon;Lee, Sang-Hoon
    • Journal of the Korean Operations Research and Management Science Society
    • /
    • v.20 no.3
    • /
    • pp.123-146
    • /
    • 1995
  • Several quality control schemes have been extensively compared using multivariate normal data sets simulated with various correlation structures. They include multiple univariate CUSUM charts, multivariate EWMA charts, multivariate CUSUM charts and Shewhart T$^{3}$ chart. This paper considers a new approach of the multivariate EWMA chart, in which the smoothing matrix has full elements instead of only diagonal elements. Performance of the schemes is measured by avaerage run length (ARL), coefficient of variation of run length (CVRL) and rank in order of signaling of off-target shifts in the process mean vector. The schemes are also compared by noncentrality parameter. The multiple univariate CUSUM charts are generally affected by the correlation structure. The multivariate EWMA charts provide better ARL performance. Especially, the new EWMA chart shows remarkable results in small shifts.

  • PDF

A Synthetic Chart to Monitor The Defect Rate for High-Yield Processes

  • Kusukawa, Etsuko;Ohta, Hiroshi
    • Industrial Engineering and Management Systems
    • /
    • v.4 no.2
    • /
    • pp.158-164
    • /
    • 2005
  • Kusukawa and Ohta presented the $CS_{CQ-r}$ chart to monitor the process defect $rate{\lambda}$ in high-yield processes that is derived from the count of defects. The $CS_{CQ-r}$ chart is more sensitive to $monitor{\lambda}$ than the CQ (Cumulative Quantity) chart proposed by Chan et al.. As a more superior chart in high-yield processes, we propose a Synthetic chart that is the integration of the CQ_-r chart and the $CS_{CQ-r}$chart. The quality characteristic of both charts is the number of units y required to observe r $({\geq}2)$ defects. It is assumed that this quantity is an Erlang random variable from the property that the quality characteristic of the CQ chart follows the exponential distribution. In use of the proposed Synthetic chart, the process is initially judged as either in-control or out-of-control by using the $CS_{CQ-r}$chart. If the process was not judged as in-control by the $CS_{CQ-r}$chart, the process is successively judged by using the $CQ_{-r}$chart to confirm the judgment of the $CS_{CQ-r}$chart. Through comparisons of ARL (Average Run Length), the proposed Synthetic chart is more superior to monitor the process defect rate in high-yield processes to the stand-alone $CS_{CQ-r}$ chart.

Service Quality Assessment of University Libraries in Korea using LibQUAL+ : A Case Study (LibQUAL+를 활용한 국내 대학도서관 서비스 품질 측정 사례 조사)

  • Shim, Wonsik;Lee, Eun-Chul
    • Journal of the Korean Society for information Management
    • /
    • v.30 no.2
    • /
    • pp.245-268
    • /
    • 2013
  • The paper describes a case study in which Sungkyunkwan University Library participated in the official ARL(Assoication of Research Libraries) LibQUAL+ evaluation program. LibQUAL+ model is based on the SERVQUAL service quality evaluation model originally developed in the marketing area. It details a number of processes including translation of the LibQUAL+ survey instrument into Korean, selection of study sample and choice of survey versions. In addition, it offers a number of strategies that can be adopted in order to analyze the survey data for various comparisons among different user groups and institutions. LibQUAL+ is more that a survey instrument; it a holistic system for assessing library service quality. Despite criticisms on LibQUAL+, we expect that university libraries in Korean will benefit from participating in the program. It is preferable that a group of libraries form a consortium to participate in the LibQUAL+ program as opposed to individual participation. The consortium can function as a learning community through various workshops and sharing activities, thus elevate the overall evaluation efforts in Korean libraries to a higher level.

Comparisons of the Performance with Bayes Estimator and MLE for Control Charts Based on Geometric Distribution (기하분포에 기초한 관리도에서 베이즈추정량과 최대우도추정량 사용의 성능 비교)

  • Hong, Hwiju;Lee, Jaeheon
    • The Korean Journal of Applied Statistics
    • /
    • v.28 no.5
    • /
    • pp.907-920
    • /
    • 2015
  • Charts based on geometric distribution are effective to monitor the proportion of nonconforming items in high-quality processes where the in-control proportion nonconforming is low. The implementation of this chart is often based on the assumption that in-control proportion nonconforming is known or accurately estimated. However, accurate parameter estimation is very difficult and may require a larger sample size than that available in practice for high-quality process where the proportion of nonconforming items is very small. An inaccurate estimate of the parameter can result in estimated control limits that cause unreliability in the monitoring process. The maximum likelihood estimator (MLE) is often used to estimate in-control proportion nonconforming. In this paper, we recommend a Bayes estimator for the in-control proportion nonconforming to incorporate practitioner knowledge and avoid estimation issues when no nonconforming items are observed in the Phase I sample. The effects of parameter estimation on the geometric chart and the geometric CUSUM chart are considered when the MLE and the Bayes estimator are used. The results show that chart performance with estimated control limits based on the Bayes estimator is generally better than that based on the MLE.