• Journal of Korean Society for Quality Management
• /
• v.31 no.4
• /
• pp.1-18
• /
• 2003

Quality is a critical competitive factor in today's environment because of the impact of quality on costs and delivery. Many companies regard quality as a key concept of company strategy in order to achieve the competitive edge. Measuring and reporting quality cost is the first step in quality management program. The supposition of quality cost model is that investment in prevention activities will bring rewards from reduced failure costs, and that further investment in prevention activities will show profits from reduced appraisal costs. In this study, the degree of quality cost deviation is conceptualized. This means a deviation between the ideal and present ranking in the amounts of quality cost categories. This study analysed that the effect of its deviation on quality management activity and performance variables. However, there are no difference in these variables. The major reason is that most of companies are endeavoring for quality management but operating quality cost system unsystematically. The review against a prevention and appraisal activity is necessary.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.116.3-116
• /
• 2001

A diagnosis methodology for thickness quality in hot finishing mill is proposed based on multivariate statistical analysis. The thickness of hot strip is a key quality factor that is measured by x-ray thickness gauge. Currently, the thickness quality is guaranteed by upper and lower limit of thickness deviation from target thickness. But if any over-limit is occurred, there is no in-line method to identify the causes. In this paper, many parameters are extracted from the thickness deviation signal such as mean deviation(top, middle, tail), rms deviation(top, middle, tail) and peak deviation(top, middle, tail) as time domain parameters ...

• Journal of Korean Society on Water Environment
• /
• v.20 no.4
• /
• pp.352-356
• /
• 2004

Variations of water quality parameters were investigated for last 13 years in Han river. Deviation from 3 month moving average was suggested for the variation analysis. Many parameters of mainstream and tributaries showed similar monthly fluctuations. Suspended solid of mainstream showed higher fluctuation than that of tributaries due to summer flood. Contrarily, the organic parameters such as BOD, COD, and TN showed lower fluctuations in the mainstreams. The magnitude of deviation was in the order of pH < DO, COD, temp. < BOD, TN < TP, SS. Strong correlation was found in BOD data of adjacent sites. Main sites showed low deviation in comparison to adjacent common sites of mainstream (1:2.4). Mainstream showed low deviation in comparison to tributaries (1:1.7). Seasonal tendency of monthly BOD was confirmed using autocorrelation function. The deviation was in inverse proportion to the magnitude of BOD.

• Journal of radiological science and technology
• /
• v.43 no.2
• /
• pp.115-121
• /
• 2020

In a digital radiation system using a Flat Panel Detector, we attempted to the quality control of digital radiography system using the Exposure Index and Deviation Index. Calibration was performed with the radiation quality suggested by the International Electrotechnical Commission, and through an experiment using a phantom, appropriate inspection radiation conditions applicable to medical institutions were selected. The study was conducted using the selected radiation conditions. Through those chest posterior anterior image, information such as examination conditions and exposure index was obtained. The deviation index was derived by analyzing the exposure index based on the target exposure index calculated by the phantom study. As for the analyzed exposure index, 97.1% was distributed within the range of ± 2.0 based on the deviation index. Quality control of medical images should be performed through management of inspection conditions through exposure index and deviation index and management of medical images.

• Proceedings of the KSR Conference
• /
• 2000.11a
• /
• pp.450-457
• /
• 2000

This paper establishes a scheme to estimate track quality using standard deviation and deterioration rate of track irregularities. To provide index of quality, standard deviation and deterioration rate of track irregularities are analyed. As an index, standard deviation and deterioration rate were applied to decision of corrective maintenance and replacement maintenance, respectively. Further, this paper proposes a basic scheme for a modernization of mechanize track maintenance that using MTT(Multiple Tie Tamper) and Ballast Cleaner.

• The Korean Journal of Rehabilitation Nursing
• /
• v.5 no.2
• /
• pp.156-165
• /
• 2002

The objective of this study was to apply a dementia prevention program to the subjects who were suspected of dementia and test its effect. This study was one group pretest-posttest design. The dementia prevention program was applied for 20 weeks to the 19 subjects who were suspected of dementia after a screen test among 638 subjects enrolled in 10 senior citizen's centers in G city. The scores of self-efficacy, cognition, quality of life were measured before and after the program. The data collected were analyzed using a SPSS (statistical analysis system) program, and frequencies, averages and standard deviations were obtained. The differences of the scores of the pretest and posttest were analyzed with Mann-Whitney test and sign test. The results were as follows: 1. After the program, the average score of self-efficacy was increased from 75.31 (standard deviation 11.99) to 84.26 (standard deviation 13.92). 2. There are no differences between the average scores of physical and psychological quality of life, however, the average score of social quality of life was slightly increased from 2.25 (standard deviation 0.40) to 2.53 (standard deviation 0.43), and the overall score of social quality of life was low. 3. The average score of cognition was significantly increased from 21.00 (standard deviation 2.60) to 24.58 (standard deviation 3.37), thus, it was found that the program was effective to improve the cognition level. 4. The score differences of self-efficacy, quality of life, cognition between the pretest and posttest were statistically significant. 5. The score differences of quality of life between the pretest and posttest were found to be dependent on marital status, exercise and regular checkup yes or no. In conclusion, the program was effective to prevent the subjects suspected of dementia from dementia.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.39 no.1
• /
• pp.1-12
• /
• 2014

This article proposes a variable sampling interval (VSI) $\bar{X}$ control chart using weighted standard deviation (WSD) method for skewed populations. The WSD method decomposes the standard deviation of a quality characteristic into upper and lower deviations and adjusts control limits and warning limits of a control chart in accordance with the direction and degree of skewness. A control chart constant is derived for estimating the standard deviation of skewed distributions with the mean of sample standard deviations. The proposed chart is compared with the conventional VSI $\bar{X}$ control chart under some skewed distributions. Simulation study shows that the proposed WSD VSI chart can control the in-control average time to signal (ATS) as an adequate level better than the conventional VSI chart, and the proposed chart can detect a decrease in the process mean of a quality characteristic following a positively skewed distribution more quickly than the standard VSI chart.

• Journal of Korean Society for Quality Management
• /
• v.43 no.1
• /
• pp.57-66
• /
• 2015

Purpose: The purpose of this study is to apply the constrained Bayesian estimation methodology for product quality control process and prove the effectiveness of the product management by comparing with the well-known Bayes estimator through data performance result. Methods: The Bayes and constrained Bayes estimators were produced based on the theoretical background and for confirming the effectiveness of suggested application, the deviation index was defined and calculated for the comparison. Results: The statistical analysis result shows that applying the suggested estimation methodology, that is, constrained Bayes estimator improves the effectiveness of the index with regard to reduce the error by matching the first two empirical moments. Conclusion: Considering the advanced Bayesian approaches such as constrained Bayes estimation for the product quality control process, the newly defined deviation index reduces the error for estimating the parameter histogram which is reflected both location and deviation parameters and furthermore various Bayesian perspective approaches seems to be meaningful for managing the product quality control process.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1997.10a
• /
• pp.729-736
• /
• 1997

This paper gives the information of field concrete placed under raining condition. Experimental factors in this study are concrete strength, standard deviation and coefficient of variation. The results are as follows: 1. The strength of field concrete placed under raining condition is not largely dependent on the raining condition. 2. But, the quality of concrete is very critical.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.28 no.4
• /
• pp.116-123
• /
• 2005

The traditional process capability indices Cp, Cpk, Cpm, $Cpm^+$ have been used to characterize process performance on the basis of univariate quality characteristics. Cp, Cpk consider the process variation, Cpm considers both the process variation and the process deviation from target and Cpm+ considers economic loss for the process deviation from target. In manufacturing industry, there is growing interest in quantitative measures of process variation under multivariate duality characteristics. The multivariate process capability index incorporates both the process variation and the process deviation from target or considers expected loss caused by the process deviation from target. This paper proposes multivariate capability index based on the expected loss derived from multivariate normal distribution.