• Journal of Korean Society for Quality Management
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• v.24 no.3
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• pp.111-132
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• 1996

Taguchi's parameter design is to determine optimal settings of design parameters of a product or a process such that the characteristics of a product exhibit small variabilities around their target values. His analysis of the problem has focused only on a single characteristic or response, but the quality of most products is seldom defined by a characteristic, and is rather the composite of a great number of characteristics which are often interrelated and nearly always measured in a variety of units. The critical problem in dealing with multiple characteristics is how to compromise the conflicts among the selected levels of the design parameters for each individual characteristic. In this paper, the EXTOPSIS Model using SN ratio which can be optimized by univariate technique is proposed and a parameter design procedure to achieve the optimal compromise among several different response variables is developed. Two existing case studies are solved by the proposed method and the results are compared with ones by the sum of SN ratios, the expected weighted loss, and the desirability function.

• The Korean Journal of Applied Statistics
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• v.10 no.1
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• pp.69-84
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• 1997

We consider a linear calibration problem, $y_i = $$\alpha + \beta (x_i - x_0) + \epsilon_i$, $i=1, 2, {\cdot}{\cdot},n$ $y_f = \alpha + \beta (x_f - x_0) + \epsilon, $ where we observe $(x_i, y_i)$'s for the controlled calibration experiments and later we make inference about $x_f$ from a new observation $y_f$. The objective of the calibration design problem is to find the optimal design $x = (x_i, \cdots, x_n$ that gives the best estimates for $x_f$. We compare Kim(1989)'s Bayesian design which minimizes the expected value of the posterior variance of $x_f$ and some optimal designs from literature. Kim suggested the Bayesian optimal design based on the analysis of the characteristics of the expected loss function and numerical must be equal to the prior mean and that the sum of squares be as large as possible. The designs to be compared are (1) Buonaccorsi(1986)'s AV optimal design that minimizes the average asymptotic variance of the classical estimators, (2) D-optimal and A-optimal design for the linear regression model that optimize some functions of $M(x) = \sum x_i x_i'$, and (3) Hunter & Lamboy (1981)'s reference design from their paper. In order to compare the designs which are optimal in some sense, we consider two criteria. First, we compare them by the expected posterior variance criterion and secondly, we perform the Monte Carlo simulation to obtain the HPD intervals and compare the lengths of them. If the prior mean of $x_f$ is at the center of the finite design interval, then the Bayesian, AV optimal, D-optimal and A-optimal designs are indentical and they are equally weighted end-point design. However if the prior mean is not at the center, then they are not expected to be identical.In this case, we demonstrate that the almost Bayesian-optimal design was slightly better than the approximate AV optimal design. We also investigate the effects of the prior variance of the parameters and solution for the case when the number of experiments is odd.

• The Journal of Korean Society for School & Community Health Education
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• v.20 no.1
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• pp.1-14
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• 2019

Objectives: There are few studies which reflects of each generation's own features, of the New Middle Age and the Elderly's hearing status and their quality of life even though the population of old age has been weighted as baby boom generation's entering into old age. This study is to identify the effects of the new middle age and the elderly's hearing status on their quality of life and to prepare the customized health policies for their health promotion and quality of life improvement as well as the base line data for hearing enhancement programs. Methods: This study was analyzed using the data of the 7th term of the National Health and Nutrition Survey of the Disease Management headquarters. Out of 8,150 adults over the age of 50 who participated in the hearing test, 3,306 were selected and analyzed. Results: At the result of identifying the correlation of hearing status and the quality of life between the New Middle Age and the Elderly, it was confirmed that hearing loss affects low quality of life. The average of quality of life between the New Middle Age and the Elderly was 0.95 and 0.85 each, resulting in higher quality of life in New Middle Age than in the Elderly. The factors affecting the quality of life of the New Middle Age were the level of the education, household income, the type of health insurance, subjective health status. The factors affecting the quality of life of the Elderly were gender, the type of health insurance, subjective health status. Conclusion: Hearing loss of the New Middle Age and the Elderly affects their low quality of life. Therefore the development and the provision of policy program is needed, so as to maintain and manage hearing through age-specific health education. It is expected that the second half of the New Middle Age's life will be much happier, if not taking the treatment-oriented approach of hearing loss only but strengthening the education needed for the maintenance and the management of healthy hearing at their work place, where 50 and 60 generations' workforce has been increased.

• Current Applied Physics
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• v.18 no.11
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• pp.1268-1274
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• 2018

We have investigated the effects of chemical rounding (CR) on the surface passivation and/or antireflection performance of $AlO_{x^-}$ and $AlO_x/SiN_x:H$ stack-passivated pyramid textured $p^+$-emitters with two different boron doping concentrations, and on the performance of bifacial n-PERT Si solar cells with a front pyramid textured $p^+$-emitter. From experimental results, we found that chemical rounding markedly enhances the passivation performance of $AlO_x$ layers on pyramid textured $p^+$-emitters, and the level of performance enhancement strongly depends on boron doping concentration. Meanwhile, chemical rounding increases solar-weighted reflectance ($R_{SW}$) from ~2.5 to ~3.7% for the $AlO_x/SiN_x:H$ stack-passivated pyramid textured $p^+$-emitters after 200-sec chemical rounding. Consequently, compared to non-rounded bifacial n-PERT Si cells, the short circuit current density Jsc of 200-sec-rounded bifacial n-PERT Si cells with ~60 and ${\sim}100{\Omega}/sq$ $p^+$-emitters is reduced by 0.8 and $0.6mA/cm^2$, respectively under front $p^+$-emitter side illumination. However, the loss in the short circuit current density Jsc is fully offset by the increased fill factor FF by 0.8 and 1.5% for the 200-sec-rounded cells with ~60 and ${\im}100{\Omega}/sq$ $p^+$-emitters, respectively. In particular, the cell efficiency of the 200-sec-rounded cells with a ${\sim}100{\Omega}/sq$ $p^+$-emitter is enhanced as a result, compared to that of the non-rounded cells. Based on our results, it could be expected that the cell efficiency of bifacial n-PERT Si cells would be improved without additional complicated and costly processes if chemical rounding and boron doping processes can be properly optimized.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.637-651
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• 2019

In the event of a major accident such as an explosion in a refinery or a petrochemical plant, it has caused a serious loss of life and property and has had a great impact on the insurance market. In the case of catastrophic incidents occurring in process industries such as refinery and petrochemical plants, only the proximate causes of loss have been drawn and studied from inspectors or claims adjustors responsible for claims of property insurers, incident cause investigators, and national forensic service workers. However, it has not been done well for conducting root cause analysis (RCA) and identifying the factors that contributed to the failure and establishing preventive measures before leading to chemical plant's catastrophic incidents. In this study, the criteria of warning signs on CCPS catastrophic incident waning sign self-assessment tool which was derived through the RCA method and the contribution factor analysis method using the swiss cheese model principle has been reviewed first. Secondly, in order to determine the major incident warning signs in an actual chemical plant, 614 recommendations which have been issued during last the 17 years by loss control engineers of global reinsurers were analyzed. Finally, in order to facilitate the assessment index for catastrophic incident warning signs, the criteria for the catastrophic incident warning sign index at chemical plants were grouped by type and classified into upper category and lower category. Then, a catastrophic incident warning sign index for a chemical plant was developed using the weighted values of each category derived by applying the analytic hierarchy process (pairwise comparison method) through a questionnaire answered by relevant experts of the chemical plant. It is expected that the final 'assessment index for catastrophic incident warning signs' can be utilized by the refinery and petrochemical plant's internal as well as external auditors to assess vulnerability levels related to incident warning signs, and identify the elements of incident warning signs that need to be tracked and managed to prevent the occurrence of serious incidents in the future.

• Journal of Preventive Medicine and Public Health
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• v.39 no.2
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• pp.149-158
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• 2006

Objectives : We wanted to evaluate the economic value of a pharmaceutical product, Kremezin, for treating patients with chronic renal failure (CRF) by estimating the amount of cost savings due to its effect for delaying the initiation of dialysis treatments. Methods : We defined a conventional treatment for CRF accompanied by Kremezin therapy as 'the treatment group' and only conventional treatment as 'the alternative group.' The types of costs included were direct medical and nonmedical costs and costs of productivity loss. The information on the effect of Kremezin was obtained from the results of earlier clinical studies. Cost information was derived from the administrative data for 20 hemodialysis and 20 peritoneal dialysis patients from one tertiary care hospital, and also from the administrative data of 10 hemodialysis patients from one free-standing dialysis center. Per-capita cost savings resulting from Kremezin therapy were separately estimated for the cases with delay for the onset of hemodialysis and the cases with immediate performance of peritoneal dialysis. By computing the weighted average for the cases of hemodialysis and peritoneal dialysis, the expected per-capita cost savings of a patient with CRF was obtained. Using a discount rate of 5%, future cost savings were converted to the present value. Results : The present value of cumulative cost savings per patient with CRF from the societal perspective would be $18,555,000{\sim}29,410,000$ Won or $72,104,000{\sim}112,523,000$ Won if Kremezin delays the initiation of dialysis by 1 or 4 years. Conclusions : The estimated amount of cost savings resulting from treating CRF patients with Kremezin confirms that its effect for delaying the onset of dialysis treatments has a considerable economic value.