• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2505-2510
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• 2009

Semiconductor processes need measurement to confirm where there are problems in quality after progresses manufacturing process. This paper suggests equipment and automatic measure sampling method that control monitoring ratio according to change point occurrence availability of process that is not measure method by the existent simple ratio rate. This paper defines measure section as ailment section, metastable section and stability section by change point standard and create statistical model of each section and developed suitable measure rate model by section. As a result, we have accomplished maximum throughput and minimum sampling number that needs to maintain constant level of quality. Proposed method minimizes load of measure process by brings production quality sophistication and decrease of process badness and lowers measure rate in stable section making perception about problem occurrence quick heightening measure rate at change point occurrence.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.474-478
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• 1996

Process monitoring in laser welding is essential for automation and quality control of products. Various signals from laser welding, such as plasma, sound, optical signals, etc., are utilized for monitoring the process and detecting abnormal weld conditions. In this study, both W light from plasma formed above the weld pool and IR signal from the melting pool are detected with photodiodes and PC-based A/D board, and analyzed to give a guidance about the weld quality. Experimental results show the possibility of using the signals for predicting and evaluating the weld qualify and adapting into the system for on-line process monitoring.

• Journal of Korean Society for Quality Management
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• v.28 no.2
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• pp.1-16
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• 2000

This paper considers the problem of determining the optimal process mean and screening specification limits of a surrogate variable associated with product quality under two-stage screening procedure. In two-stage screening, the surrogate variable is inspected first to decide whether an item should be accepted, rejected or additional observations should be taken. If additional observations are required, the performance variable of interest is then observed to classify the undecided items. Assuming that the performance variable and the surrogate variable are jointly normally distributed, the optimal process mean and the screening limits are obtained by maximizing the expected profit which includes selling price, production, reprocessing, inspection and penalty costs. A numerical example is presented and numerical studies are performed to compare the proposed two-stage screening procedure with single-stage screening procedures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.745-750
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• 2014

The chatter vibration in the machining process plays bad role in machining quality such as high roughness as well as tool life and machine failure. And the grinding process under this risk in the fully automated factory is exposed to the unexpected mass machining quality problem. Studying the vibration signal of the hub bearing grinding process, the reason of chatter vibration was explained with the specific machining pattern of chatter. And this study suggests the chatter detecting method in the production line, which is monitoring the peak acceleration level around the natural frequencies of the specimen, and calculating kurtosis value by assuming the chatter is related to the resonance of the specimen. The suggested method was applied to the vehicle hub bearing grinding process and proved good to detecting the chatter induced machining quality problem.

• Journal of Digital Convergence
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• v.3 no.2
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• pp.23-37
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• 2005

On the situation cooperating with business partners on the supply chain, systematic decision making process is a critical issue for them. The two major issues of purchasing strategy such as selecting vendors and managing them are important part of their overall business activities. This study mainly focus on the former issue of the vendor selection. Through the empirical study, analytical hierarchy process (AHP) method was applied to select vendors among supplier vendors based on four selection criteria such as the level of quality, product on management ability, delivery, and price. The results of study showed the main criteria of vender selection was the ability of quality management. The vender selected based on AHP and the current selection method was different, but implicitly projected the dilemma situation between quality and price which occurs in decision making process of real life.

• 한국디지털정책학회:학술대회논문집
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• 2005.11a
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• pp.367-381
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• 2005

On the situation cooperating with business partners on the supply chain, systematic decision making process is a critical issue for them. The two major issues of purchasing strategy such as selecting vendors and managing them are important part of their overall business activities. This study mainly focus on the former issue of the vendor selection. Through the empirical study, analytical hierarchy process (AHP) method was applied to select vendors among supplier vendors based on four selection criteria such as the level of quality, product on management ability, delivery, and price. The results of study showed the main criteria of vender selection was the ability of quality management. The vender selected based on AHP and the current selection method was different, but implicitly projected the dilemma situation between quality and price which occurs in decision making process of real life.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.6
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• pp.784-796
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• 2019

As the size and complexity of software increases, it is important to ensure the quality of software through testing. Many organizations refer to international standards or test process models to improve the quality of software through establishing a systematic test process. However, these standards and process models provide general processes that do not reflect the characteristics of the domain or the organization's test policies and strategies. To establish a test process that reflects the characteristics of the organization, test policies and strategies based on the organization's quality objectives and the organizational and domain characteristics should be reflected. This study proposes specific methods for eliciting activities and information to establish organizational software test policies and strategies that are essential to establishing a test process that reflects the characteristics of the organization and the system.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.135-141
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• 2006

Cusum control chart is used for the purpose of controling the process mean. We consider the problem related to cusum chart for controling process variance. Previous researches have considered the same problem. The main difficulty shown in the related researches was to derive the ARL function which characterizes the properties of the chart. Sample variance, differently with sample mean, follows chi-squared type distribution, even when the quality characteristics are assumed to be normally distributed. The ARL function of cusum is described by a type of integral equation. Since the solution of the integral equation for non-normal distribution is not known well, people used simulation method instead of solving the integral equation directly, or approximation method by taking logarithm of the sample variance. Recently a new method to solve the integral equation for Erlang distribution was published. Here we consider the steps to apply the solution to the problem of controling process variance.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.120-121
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• 2021

This study examines the performance of the pre-treatment process system to use CGS, a by-product generated in IGCC, as a concrete fine aggregate for construction materials, on the quality of CGS fine aggregate. As a result of the analysis, it is judged that the quality of fine aggregates of CGS can be improved at both density, absorption rate, and 0.08mm body passage amount after the hydroelectric screening process using water as a medium during the pretreatment process. It is believed that it can be used as basic data for national standard certification of CGS fine aggregates in the future.

• Journal of Korean Society for Quality Management
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• v.32 no.2
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• pp.201-211
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• 2004

Process adjustment is a complimentary tool to process monitoring in process control. Process adjustment directs on maintaining a process output close to a target value by manipulating another controllable variable, by which significant process improvement can be achieved. Therefore, this approach can be applied to the 'Improve' stage of Six Sigma strategy. Though the optimal control rule minimizes process variability in general, it may not properly function when special causes occur in underlying process, resulting in off-target bias and increased variability in the adjusted output process, possibly for long periods. In this paper, we consider a responsive feedback control system and the minimum mean square error control rule. The bias in the adjusted output process is investigated in a general framework, especially focussing on stationary underlying process and the special cause of level shift type. Illustrative examples are employed to illustrate the issues discussed.