• Journal of KIISE
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• v.42 no.3
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• pp.289-294
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• 2015

The consensus problem is finding a representative string, called a consensus, of a given set S of k strings. Circular strings are different from linear strings in that the last symbol precedes the first symbol. Given a set S of circular strings of length n over an alphabet ${\Sigma}$, we first present an $O({\mid}{\Sigma}{\mid}nlogn)$ time parallel algorithm for finding a consensus of S minimizing both radius and distance sum when k=3 using O(n) threads. Then we present an $O({\mid}{\Sigma}{\mid}n^2logn)$ time parallel algorithm for finding a consensus of S minimizing distance sum when k=4 using O(n) threads. Finally, we compare execution times of our algorithms implemented using CUDA with corresponding sequential algorithms.

• Journal of Applied Reliability
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• v.6 no.3
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• pp.239-254
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• 2006

In this research, first, the effect of Six Sigma activities and business performance will be checked based on case studies involving companies adopting Six Sigma and, secondly, the Six Sigma training effectiveness, Customer Satisfaction and Financial Performance, etc, will be evaluated to find out how related to Six Sigma Implementation. Finally, Six Sigma's Implementation Categories will be analyzed. The method used in this research was to select the research model and research hypothesis based on theoretical studies and the interesting aspects of the recent Six Sigma, along with case studies and research based on actual proof. Case studies and research based on actual proof showed that among 11 companies analyzed, a total of 11 companies obtained good results, and KIs were found to be factors of their success.

• International Journal of Automotive Technology
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• v.4 no.4
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• pp.193-201
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• 2003

The problem of brake judder is typically caused by defects of quality manufacturing. DFSS (Design for six sigma) is a design process for quality improvement. DFSS will result in more improved but less expensive quality products. This paper presents an implementation of DFSS for quality improvement of the brake judder of heavy-duty trucks. Carrying out 5 steps of DFSS, the major reasons for defects of quality are found. The numerical approximation of the brake system is derived by means of the response surface method. Its quality for brake judder is improved by using the sigma based robust design methodology. Results are compared between the conventional deterministic optimal design and the proposed sigma based robust design. The proposed one shows that manufacturing cost may increase as the quality level increase. The proposed one, however, is more economical in aspect of the overall cost since the probability of failure dramatically goes down.

• Journal of Korean Society for Quality Management
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• v.35 no.2
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• pp.84-98
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• 2007

Six Sigma advocates rigorous application of quality management tool. Using Six Sigma program provides a mechanism for service organization to achieve organization's goal and customer satisfaction. A model on Six sigma in service organization was developed and applied for the service organization. Questionnaire was developed, and data was collected and analyzed for this study. Conclusively, 6 sigma leadership is the important drivers to process management and customer relationship management. Process management and customer relationship management are significantly related to the job performance and customer satisfaction.

• Journal of Microbiology
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• v.38 no.3
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• pp.176-179
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• 2000

A challenge phage system was used to study the DNA-protein interaction between C4-dicarboxylic acid transport protein D(DCTD) or $\sigma$54, and a $\sigma$54 -dependent promoter, dctAp. R. meliloti dctA promoter regulatory region replaced the Omnt site on the phage. S. typhimurium strains overproducing either DCTD or $\sigma$54 directed this challenge phage towards lysogency, indicating that DCTD or E$\sigma$54 recognized the dctA promoter on the phage and repressed transcription of the ant gene. These challenge phage constructs will be useful for examining interactions between DCTD(or $\sigma$54) and the dctA promoter region.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.298-301
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• 2004

In the last ten years, manufacturing companies like GE, IBM, Motorola and service companies like GE Capital and CITIBANK have realized that Six Sigma has standed for quality reform movemant. Six Sigma management which makes the critic effects on the quality management have enlarged and applied office indirect work process and service department as well beyond question manufacturing process. Then Can Six Sigma application methodology from manufacturing industry be applied to service industry without transformation? Can Six Sigma be applied on improvement of Information system quality which is the critic key figure of current successful companies? These questions would be resolved by conducting researches about application and evaluation of Six Sigma on manufacturing industry and service industry. This paper will furnish information of Six Sigma's new function for future business situation through comparing those researches

• Journal of the Korean Society for Heat Treatment
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• v.14 no.5
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• pp.286-291
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• 2001

This study was carried out to investigate the influence of ${\sigma}$ phase on the microstructure and mechanical properties in super duplex stainless steel. The precipitation of ${\sigma}$ phase during isothermal heat treatment showed the type S curves with a certain incubation period. The precipitation of ${\sigma}$ phase was precipitated at ferrite phase and interface of ferrite and austenite. Under the state of isothermal transformation, the precipitation of ${\sigma}$ phase was stimulated by applied stress. With increasing of volume fraction of precipitated ${\sigma}$ phase, tensile strength was increased and elongation was decreased with linear relationship, while in case of precipitated ${\sigma}$ phase was 5% over, impact value was rapidly decreased.

• Journal of Korean Society for Quality Management
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• v.42 no.3
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• pp.361-372
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• 2014

Purpose: In this paper, we investigate whether the endeavors for 6 sigma quality management by a firm have positive effects on its financial performance and the length of 6 sigma implemented period affects its financial status. Methods: We conduct the analysis using the data from Workplace Panel Survey 2009. We use multiple linear regression in order to analyze the relationship between the efforts for quality management and financial performance. Specifically, the return on assets (ROA) and return on equity (ROE) are investigated as dependent variables and the efforts for quality management as independent variable. The Box-Cox transformation and Cook's distance are also used. Results: As a result of the analysis, the indication is that companies that put effect into the six sigma quality management have a positive result in its financial status. In detail, the efforts for six sigma quality management have positive effects on total asset turnover ratio and six sigma implemented period on net income to net sales ratio. Additionally, companies with longer(shorter) period of six sigma program have more (less) improvement in its financial status. Conclusion: It can be concluded that the company's efforts for quality management positively influence financial performance.

• Journal of Welding and Joining
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• v.31 no.5
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• pp.20-25
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• 2013

This study was carried out to investigate the influence of a sigma phase precipitation on the pitting corrosion resistance and microstructural change of super duplex stainless steels(UNS S32750). The welds made by FCAW (Flux Cored Arc Welding) were heat treated ($930^{\circ}C$, $1080^{\circ}C$, $1230^{\circ}C$) and quenched. Based on the microstructural examination, it was found that the ${\sigma}$ phase was formed in base metals and welds heat treated at $930^{\circ}C$ while there were little ${\sigma}$phases formed in base metals and weld metal experienced the relatively fast cooling from $1080^{\circ}C$ and $1230^{\circ}C$. On the other hand, the most weight loss due to pitting corrosion occurred in base and weld metals heat treated at $930^{\circ}C$. It was confirmed that the pitting corrosion occurred in the phase boundaries of ferrite/sigma and austenite/sigma. The pitting corrosion resistance decreased owing to an increase in Cr, Mo depleted areas adjacent to the intermetallic phases such as ${\sigma}$phases. The hardness was greatly increased due to the precipitation ${\sigma}$phases.

• Geotechnical Engineering
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• v.13 no.4
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• pp.149-162
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• 1997

A series of torsion shear tests were performed to study the strength characteristics of sand under various stress paths during rotation of principal stress. These results can be classified into two groups of 25cm and 40cm according to the height of specimen, and toy que was applied only in the clockwise direction. In this study, strength characteristics of sand for the principal stress ratio in torsion sheartests were investigated and their results were compared with Lade's failure criterion. And the effect for specimen was considered. From the results of tests, friction angle of sand was affected by the deviatoric principal stress ratio $b:(\sigma_2 -\sigma_s)/(\sigma_2, -\sigma_3)$Failure strength of sand was determined not by the stress paths but by the current stress state. From comparison of specimens on 25cm and 40cm height, effect of end restraint could not be found. In the test where b is over 0.5 due to extension force, necking phenomenon by the strain localization was found.