• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.63
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• pp.1-12
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• 2001

When designing the parameter on the multiple quality characteristics, there has been a study for optimization of problems, but there has been few former study on the possible conflicting phenomena in consideration of the correlations among the characteristics. To solve the issue on the optimal design for multiple quality characteristics, this study propose the expected loss function with cross-product terms among the characteristics and derived range of the coefficients of the terms. The model will be used to determine the global optimal design parameters where there exists the conflict among the characteristics, which shows difference in optimal design parameters for the individual characteristics. Also, when an adjustment factor exists for each m performance characteristics, this research propose a method by minimizing the expected loss after adjustment.

• Journal of the Korean Data and Information Science Society
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• v.14 no.3
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• pp.545-551
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• 2003

Robust design is to identify appropriate settings of control factors that make the system's performance robust to changes in the noise factors that represent the source of variation. In this paper we propose how to simultaneously optimize multiple quality characteristics using the principal component analysis of multivariate statistical analysis. An example is illustrated to compare it with already proposed method.

• 한국데이터정보과학회:학술대회논문집
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• 2004.04a
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• pp.131-139
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• 2004

Robust parameter design is to identify appropriate settings of control factors that make the system's performance robust to changes in the noise factors that represent the source of variation. In this paper, we introduce a factor analysis approach to simultaneously optimize multiple quality characteristics in the robust parameter design. An example is illustrated to compare it with already proposed method.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.11-22
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• 1994

The present works are the theoretical results of the study to develope a damping flexible coupling which has a high performance of control for the torsional vibrations of power shafts in a large machinery. It is established the analysis scheme of the multiple-leaf spring, to obtain the static coefficient of stiffness of the coupling. Also, the dynamic coefficient of stiffness and the damping coefficient of the coupling are indentified through the flow analysis for a induced flow of working fluid by the deflection of multiple-leaf springs. This paper dealt with damping contributions by the friction between each plate of the multiple-leaf spring. In this paper, it is found that the dynamic characteristics of the damping flexible coupling are strongly dependent on the stiffness and the number of the multiple-leaf spring, and also vary with the viscosity of working fluid and the vibration speed of the inner star.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.53-56
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• 2004

The mixing characteristics of a multiple transverse injection system in a scramjet combustor were studied with numerical methods. The distance among injectors on mixing characteristics were investigated. The three-dimensional Wavier-Stokes equations including k-w SST turbulence model were solved. It was shown that the mixing characteristics of a multiple transverse injection system were very different from those of a single and a dual injection system; the rear injection flow was strongly influenced by blocking effect due to the momentum flux of the front injection flow and thus had higher expansion and penetration than the front injection flow. The multiple injection system had higher mixing rate, higher penetration but had more losses of stagnation pressure than the single injection system.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.240-240
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• 2010

A multiple alloy metal nano-dots memory using FN tunneling was investigated in order to confirm its structural possibility for future flash memory. In this work, a multiple FePt nano-dots device with a high work function (~5.2 eV) and extremely high dot density (${\sim}\;1.2{\times}10^{13}/cm^2$) was fabricated. Its structural effect for multiple layers was evaluated and compared to one with a single layer in terms of the cell characteristics and reliability. We confirm that MOS capacitor structures with 2-4 multiple FePt nano-dot layers provide a larger threshold voltage window and better retention characteristics. Furthermore, it was also revealed that several process parameters for block oxide and inter-tunnel oxide between the nano-dot layers are very important to improve the efficiency of electron injection into multiple nano-dots. From these results, it is expected that a multiple FePt nano-dots memory using Fowler-Nordheim (FN)-tunneling could be a candidate structure for future flash memory.

• Corrosion Science and Technology
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• v.19 no.6
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• pp.302-309
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• 2020

This study aimed to predict the pitting corrosion characteristics of AL-6XN super-austenitic steel using multiple linear regression. The variables used in the model are degree of sensitization, temperature, and pH. Experiments were designed and cyclic polarization curve tests were conducted accordingly. The data obtained from the cyclic polarization curve tests were used as training data for the multiple linear regression model. The significance of each factor in the response (critical pitting potential, repassivation potential) was analyzed. The multiple linear regression model was validated using experimental conditions that were not included in the training data. As a result, the degree of sensitization showed a greater effect than the other variables. Multiple linear regression showed poor performance for prediction of repassivation potential. On the other hand, the model showed a considerable degree of predictive performance for critical pitting potential. The coefficient of determination (R2) was 0.7745. The possibility for pitting potential prediction was confirmed using multiple linear regression.

• Proceedings of the Safety Management and Science Conference
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• 2004.11a
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• pp.69-79
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• 2004

Process capability indices are widely used in industries and quality assurance system. When designing the parameter on the multiple quality characteristics, there has been a study for optimization of problems, but there has been few former study on the possible conflicting phenomena in considertion of the correlations among the characteristics. To solve the issue on the optimal design for multiple quality characteristics, the study propose the expected loss function with cross-product terms among the characteristics and derived range of the coefficients of terms. Therefore, the analysis have to be required a multivariate statistical technique. This paper introduces to multivariate capability indices and then selects a multivariate process capability index incorporated both the process variation and the process deviation from target among these indices under the multivariate normal distribution. We propose a new multivariate capability index $MC_{pm}^{++}$ using quality loss function instead of the process variation and this index is compared with the proposed indices when quality characteristics are independent and dependent of each other.

• Quality Improvement in Health Care
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• v.2 no.2
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• pp.56-71
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• 1996

Background : Review of readmissions in health care facilities is necessary from the viewpoint of both economic concerns and quality considerations. To identify the characteristics, factors, and causes of multiple admissions in comparison with single admissions is essential for both providers and payers in order to assure quality care and efficient use of medical resources. Methods: All discharges from an university hospital in 1993 were analyzed, and the characteristics of multiple admissions were identified and were compared with those of single admissions by using the data bases of the discharge abstract and billing for reimbursement. Medical records of patients readmitted within 6 days after the previous discharge were reviewed to identify the reasons for such prompt readmission. Statistical analysis between groups of patients were performed by using SPSS. Result : The mean age was higher in multiple admissions than those of single admissions, and the average length of stay was longer in multiple admissions than in single admissions. The hospital cost per day is higher in single admissions while the cost per case is higher in multiple admissions. More than half of readmissions occurred within one month after the preceding discharges. Above 15% of the readmission within 6 days after the preceding discharges seemed to have close relationship with quality of care provided during the preceding hospitalization. The death rate of the patients readmitted within 6 days was the highest in comparison with multiple admissions and single admissions. Conclusion : Potential preventable readmissions should be reduced by identifying characteristics of multiple admissions, especially unplanned readmission, and by applying some interventions such as standard predischarge assessment or careful follow-up care after discharge for high risk readmission groups. As the results of these efforts, health care facilities could achieve quality improvement in medical care, and effective use of hospital resources.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.4
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• pp.99-111
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• 1994

Toguchi method is a systematic technique for designing high quality product at low cost. There are three steps in the Toguchi method, 1)system design, 2)parameter design, and 3)tolerance design. This paper considers the tolerance design for multiple performance characteristics which is practically important. We present two tolerance design procedures : grade selection and tolerance determining procedures. In grade selection procedure a scheme is presented that minimizes the sum of the price of low-level characteristics and the expected loss due to the variations of high-level characteristics. In tolerance determining procedure we determine the tolerances of the low-level characteristics.