• Communications for Statistical Applications and Methods
• /
• v.6 no.1
• /
• pp.77-88
• /
• 1999

A new measure of the process capability index(PCI) $\textit{C}_{cpk}$ is proposed that takes into account the proximity to the target value as well as process mean and process variation when we assessing process performance. using the semivariance estimators proposed by Choobineh and Branting (1986) and Josephy and Aczel (1993) the estimator($\textit{C}_{cpk}$) of new index has been solved and the properties of these estimators have been examined through simulations. Also we compare the performance between $\textit{C}_{cpk}$ and $\textit{C}_{jpk}$ which is developed by Johnson kotz and Pearn(1992).

• Journal of Korean Society for Quality Management
• /
• v.49 no.3
• /
• pp.327-340
• /
• 2021

Purpose: The purpose of this study is to propose a system predicting whether an electricity distribution system is abnormal by analyzing the temperature of the deteriorated system. Traditional electricity distribution system abnormality diagnosis was mainly limited to post-inspection. This research presents a remote monitoring system for detecting thermal images of the deteriorated electricity distribution system efficiently hereby providing safe and efficient abnormal diagnosis to electricians. Methods: In this study, an object detection algorithm (YOLOv5) is performed using 16,866 thermal images of electricity distribution systems provided by KEPCO(Korea Electric Power Corporation). Abnormality/Normality of the extracted system images from the algorithm are classified via the limit temperature. Each classification model, Random Forest, Support Vector Machine, XGBOOST is performed to explore 463,053 temperature datasets. The process capability index is employed to indicate the quality of the electricity distribution system. Results: This research performs case study with transformers representing the electricity distribution systems. The case study shows the following states: accuracy 100%, precision 100%, recall 100%, F1-score 100%. Also the case study shows the process capability index of the transformers with the following states: steady state 99.47%, caution state 0.16%, and risk state 0.37%. Conclusion: The sum of caution and risk state is 0.53%, which is higher than the actual failure rate. Also most transformer abnormalities can be detected through this monitoring system.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.24 no.63
• /
• pp.45-54
• /
• 2001

The process capability indices have been widely used in manufacturing industries to provide numerical measures of process potential and performance. This study is concerned with process controls and adjustments by incapability index $C_{pp}$ and its sub-indices. A monitoring for $\^{C}_{pp}$ would provide a convenient way to monitor changes on process capability after statistical control is established, since $C_{pp}$ simultaneously measures process variability and centering. Further, we can separate charting of process location and variability by sub-indices of $C_{pp}$, ($C_{ia}$, $C_{ip}$), without returning to $\={x}$-R chart, even though an out-of-control signals on $\^{C}_{pp}$ control chart is found.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.1
• /
• pp.162-169
• /
• 2015

In this research, technology innovation capability evaluation model for small and medium enterprises was developed. To develop technology innovation capability evaluation model, two analytic technic was used. First one is AHP (Analytic Hierarchy Process) to give weight to each main index. Second one is fuzzy set theory to represent ambiguous index to numerical value. Finally, technology innovation capability evaluation model was achieved in combination with the same weight to AHP analysis and fuzzy set theory. With these results, small and medium enterprises can know important point in terms of strengthening the innovation capability evaluation.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.36 no.4
• /
• pp.38-44
• /
• 2013

Smart phones have brought rapid changes in this competitive world. Smart phone application developers are trying their best to consider the customer requirements in the most efficient way while considering all its attributes. However smart phone service quality has been given less consideration comparatively during the last few years. This paper proposes a measurement method for improving service quality of smart phone application. This method combines the service quality performance model (SQPM) and process capability index (PCI). The service quality performance model is used to identify service items that require improvement. Process capability index is used as a measure for prioritization of those improvements. Case study was carried out to search out important communication application service attributes. customer satisfaction level data was collected for users who used the application service. A total of twenty four service attributes were found during this survey. Using the joint approach of SQPM and PCI, five significant service attributes were prioritized for service quality improvement.

• Journal of the Korean Data and Information Science Society
• /
• v.18 no.4
• /
• pp.937-943
• /
• 2007

In this paper a new process incapability index $C^*_{psks}$ is introduced for non-normal process. $C^*_{psks}$ is proposed by transformation of the $C^*_{psks}$. The use of each technique is illustrated by reference to a distribution system which includes the Pearson and Johnson functions. Accordingly, $C^*_{psks}$ is proposed as the process capability measures for non-normal process.

• Journal of Korean Society for Quality Management
• /
• v.17 no.2
• /
• pp.64-69
• /
• 1989

This paper aims at analyzing the process capability and at determining an optimal condition by experimental designs using the 2-way classification with repitition in order to maintain lower Nacl content and to refine both of a very small quantity of fatty acid and various magnetic ions in the glycerin to use ion exchange resin treatment process. An optimal condition of each level combination in both of passing temperature of cation exchange resin($A_1$, $A_2$, $A_3$) and of anion exchange resin($B_1$, $B_2$, $B_3$) is $A_3B_3$. The process capability index is improved from 0.63 to 1.40 and is interpreted as a desirable state. This analysis of process capability by experimental designs will contribute to improving productivity and quality of products.

• Journal of the Korea Safety Management & Science
• /
• v.3 no.3
• /
• pp.175-190
• /
• 2001

We propose, a new process capability index $C_{psk}$(WV) applying the weighted variance control charting method for non-normally distributed. The main idea of the weighted variance method(WVM) is to divide a skewed or asymmetric distribution into two normal distributions from its mean to create two new distributions which have the same mean but different standard deviations. In this paper we propose an example, a distributions generated from the Johnson family of distributions, to demonstrate how the weighted variance-based process capability indices perform in comparison with another two non-normal methods, namely the Clements and the Wright methods. This example shows that the weighted valiance-based indices are more consistent than the other two methods in terms of sensitivity to departure to the process mean/median from the target value for non-normal processes. Second method show using the percentage nonconforming by the Pearson, Johnson and Burr systems. This example shows a little difference between the Pearson system and Burr system, but Johnson system underestimated than the two systems for process capability.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.1
• /
• pp.182-187
• /
• 2015

Process capability indices (PCIs) have been widely used in manufacturing industries to provide a quantitative measure of process potential and performance to meet the specification limits on quality characteristics. The most of existing PCIs are concerned with a single variable. But, in many cases, people want to express a integrated PCI which includes a couple of sequential processes. In this paper, we analyzed the characteristics of system PCIs such as ${\bar{Cp}}(f)$, $SC_{pk}$, $SC_{psk}$, $C^T_{psk}(m)$ and $SC_{pm}(m)$.

• Journal of Korean Society for Quality Management
• /
• v.31 no.1
• /
• pp.109-122
• /
• 2003

This paper presents a robust process capability index(PCI) based on the expected loss derived from the empirical distribution function(EDF). We propose the EDF expected loss in order to develop a PCI that does not depends on the underlying process distribution. The EDF expected loss depends only on the sample data, so the PCI based on it is robust and it does nor require complex calculations. The inverted normal loss function(INLF) is employed in order to overcome the drawback of the quadratic loss which may Increase unboundedly outside the specification limits. A comprehensive simulation study was performed under various process distributions, in order to compare the accuracy and the precision of the proposed PCI with those of the PCI based on the expected loss derived from the normal distribution. The proposed PCI turned out to be more accurate than the normal PCI in most cases, especially when the process distribution has high kurtosis or skewness. It is expected that the proposed PCI can be utilized In real processes where the true distribution family may not be known.