• Journal of Korean Society for Quality Management
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• v.48 no.4
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• pp.535-552
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• 2020

Purpose: The main theme of this study is to derive a specific quality loss function with multiple characteristics according to the same analytical structure as the single characteristic quality loss function of Taguchi. In other words, it presents an analytical framework for measuring quality costs that can be controlled in practice. Methods: This study followed the analytical methodology through geometric, linear algebraic, and statistical approaches Results: The function suggested by this study is as follows; $$L(x_1,x_2,{\cdots},x_t)={\sum\limits_{i=1}^{t}}k_i\{x_i+{\sum\limits_{j=1}^{t}}\({\rho}_{ij}{\frac{d_i}{d_j}}\)x_j\}x_i$$ Conclusion: This paper derived the quality loss function with multiple quality characteristics to expand the usefulness of the Taguchi quality loss function. The function derived in this paper would be more meaningful to estimate quality costs under the practical situation and general structure with multiple quality characteristics than the function by linear algebraic approach in response surface analysis.

• Journal of Korean Society for Quality Management
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• v.20 no.1
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• pp.80-90
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• 1992

In industries, the capability indices $C_p$ and $C_{pk}$ can be used to provide measures of process potential capability and performance, respectively. The new approach advocated by Taguchi in quality control overcomes some problems in other approaches preventive management activities. Taguchi introduces the emphasis on loss function to improve quality of products on the side of customer. The proceeding concept of capability indices is not rational for the measurement of quality if the process mean is not equal to target value. The Taguchi approach is said to be more reasonable than the others in quality evaluation because of his loss function. However, the capability indices $C_{pm}{^+}$ and $C_{pn}$ using Taguchi's loss function only consider, acceptance cost for deviation from target value within specification limits. In other words, they do not include rejection cost for nonconformings that are failed to fall on the specification limits.

• Journal of Korean Society for Quality Management
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• v.25 no.3
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• pp.119-130
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• 1997

In this paper, we analyze quality loss function(QLF) of Taguchi. Taguchi method of QLF gives more advanced measure process capability than classic capacity(i.e. Cp). We first discuss of QLF and Cp and give one good example of QLF. Because of simplicity of QLF, it is not good fit to a, pp.y in the real field. We suggest interval quantity-loss cost function and total loss cost(TLC) which modify QLF. Also we give one example which can be obtained in the real field.

• Journal of Korean Society for Quality Management
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• v.21 no.2
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• pp.61-70
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• 1993

The concept of producer's tolerance, in contrast to the consumer's tolerance, is a natural consequence of continuous loss functions. It is based on the premise that any unit product whose quality characteristic deviated from its traget value inflicts a loss, and that this less is a continuous monotonically increasing function of the magnitude of deviation. This concept of the emphasis on loss function to improve quality of products on the side of customer is introduced by Taguchi. This paper considers the problem of determining the optimum producer's tolerance by continous loss fuction of Taguchi and proposes a probablistic model for the problem. The difference between the proposed probablistic approach and the approach taken in Taguchi is also pointed out.

• Journal of Korean Society for Quality Management
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• v.41 no.3
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• pp.443-456
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• 2013

Purpose: Recently, many quality issues are aroused in military forces, such as failures in K-series weapons, combat boots defects and 40mm ammunition explosion accident. To address these problems, this paper suggests to use so called, Defense Quality Score, which is based on Taguchi loss function and developed in this research. Methods: Current defense specification states only the minimum requirement to produce the military supplies. Therefore, it is not easy to indue the continuous quality improvement of the supplies. This research suggests to use the defense quality score which measures the current status of defense supplies'quality characteristics. Results: We applied the defense quality score concept into the hot pepper sauce and long time stockpiled ammunition. We first categorize the quality characteristics into three categories, then assign the certain amount of score based on the importance of the characteristics. Lastly, we applied the modified Taguchi loss function to calculate the achieved score of the characteristics. The perfect score is 100 and the closer to the score, the better product it indicates. Conclusions: In this research, we developed the modified Taguchi loss function to apply into the korean defense supplies. The loss function is utilized to calculate the achieved level of satisfaction of the supplies based on the defense specifications. The application of defense quality score may help to stimulate the continuous quality improvement and encourage the good will quality competition among the military providers.

• Journal of Korean Society for Quality Management
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• v.20 no.2
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• pp.11-20
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• 1992

We discuss the feed back control of the on-line QC in the Taguchi method. Taguchi(1982) used the assumptions that the quality characteristics follow an uniform distribution and the Brownian motion to draw the loss function and proposed ${\Delta}/3$ or ${\Delta}$ for the initial control limit. Adams and Woodall(1989) also proposed a different procedure but using the same loss function. We propose, in this paper the new loss function under the assumption of mainly Brownian motion and compare the results with the results of the above.

• International Journal of Quality Innovation
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• v.4 no.1
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• pp.191-204
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• 2003

The target costing technique, mathematically discussed by Sauers, only uses the $C_p index along with Taguchi loss function and $\bar{X}$-P control charts to setup goal control limits. The new specification limits derived from Taguchi loss function is linked through the $C_p value to $\bar{X}$-P control charts to obtain goal control limits. Studies have shown that the point estimator of the $C_p index, $C_p, could vary from time to time due to the sampling error. The suggested approach is to use confidence intervals, especially the lower confidence intervals, to replace the point estimator. Therefore, an improvement on target costing technique is presented by applying the lower confidence interval of the $C_p index and using both Taguchi and Spiring's loss functions together with $\bar{X}$-P charts to make this technique more robust in practice. An example is also provided to illustrate how the improved target costing technique works.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.133-139
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• 1991

If the specifications of product. in general. art determined too wide. the precision of product becomes diminished. Otherwise it costs dearly to keep the precision. Therefore, It is realistic to consider various factors in determining specification of qualify characteristics TAGUCH Idefines quality of an object as "Quality is the loss that a product causes to society after being shipped. other than any losses caused by its intrinsic function". Particularly, to improve the performances of product TAGUCHI focuses his attention on the product design and process design which enable the functional characteristics of product to he robust to noises. In this paper, by the TAGUCHI's loss function, the characteristics which affect the variation of a product performance are classified into the scrappable characteristics and the reworkable characteristics when the target values of functional characteristics have been determined. And we will determine the tolerance of each characteristic which minimize the quality cost by the cost function which considers the economic factors and probability features of each characteristic.cteristic.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.114-119
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• 2003

In this paper, the experimental design of an intake system was studied using the two microphones method and the taguchi method. The transmission loss was utilized to represent the performance of noise reduction for the intake system which was estimated by measuring sound power at inlet and outlet with two microphones, respectively. Two microphones method used in this paper was followed by wave decomposition theory The robust designing parameters of an intake system were extracted by adapting a cost function with the taguchi method, which optimized the process. Finally the effectiveness of the propose method was validated with the experimental data.

• International Journal of Quality Innovation
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• v.6 no.2
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• pp.31-45
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• 2005

The target costing technique, mathematically discussed by Sauers, only uses the $C_p$ index along with Taguchi loss function and ${\bar{X}}-R$ control charts to set up goal control limits. The new specification limits derived from Taguchi loss function is linked through the $C_p$ value to ${\bar{X}}-R$ control charts to obtain goal control limits. This study further considers the reflected normal loss function as well as the $C_{pk}$ index along with its lower confidence interval in forming goal control limits. With the use of lower confidence interval to replace the point estimator of the $C_{pk}$ index and reflected normal loss function proposed by Spiring to measure the loss to society, this modified and improved target costing technique would become more robust and applicable in practice. Finally, an example is provided to illustrate how this modified and improved target costing technique works.