• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.464-467
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• 2005

Among several polishing techniques for micro structures, polishing process using magnetorheological(MR) fluid has advantages in the finishing process of 3-D micro structures because abrasives in the fluid can reach surfaces with complex feature and play their role. Although many researchers have been trying to reveal its polishing mechanism of the MR polishing, it has not been successful because in-situ measurement of state variables is difficult and process parameters are complex. In fact, one of the key factors for applying process control methodologies, such as Run-to-Run control, is the measuring and monitoring of slurry quality because the process strongly depends on the fluid property. Therefore, it is necessary to maintain consistent slurry quality to guarantee the process repeatability. The proposed equipment achieves the longer life cycle of MR fluid and reduces the variability of products. A new method to measure the material removal rate in MRF polishing process is also proposed and discussed.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.712-720
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• 2011

Radio frequency identification (RFID) is an established technology and has the potential, in a variety of applications, to significantly reduce cost and improve performance. As RFID-enabled applications will fulfill similar tasks across a range of processes adapted to use the data gained from RFID tags, they can be considered as software products derived from a common infrastructure and assets that capture specific ions in the domain. This paper discusses a framework that supports the development of RFID-enabled applications based on a business process family model (BPFM), explicitly representing both commonalities and variabilities. To develop this framework, common activities are identified from RFID-enabled applications and the variabilities in the common activities are analyzed in detail using variation point concepts. Through this framework, RFID data is preprocessed, and thus, RFID-enabled applications can be developed without having to process RFID data. Sharing a common model and reusing assets to deploy recurrent services may be considered an advantage in terms of economic significance and the overall product quality afforded.

• Journal of Korean Society for Quality Management
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• v.28 no.4
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• pp.194-203
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• 2000

This paper is concerned with an economic selection of both the process mean and the lower limit for a continuous production process with the quadratic loss function. It is assumed that the quality characteristic is normally distributed with a known variability. A profit model is developed which involves selling price, production cost, reprocessing cost and the cost which is incurred by imperfect quality. Methods of finding optimum values of the process mean and the lower limit are presented, and a numerical example is given.

• Journal of the Korean Statistical Society
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• v.35 no.1
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• pp.37-47
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• 2006

Recently, as a result of the growing interest in modeling stationary processes with discrete marginal distributions, several models for integer valued time series have been proposed in the literature. One of these models is the integer-valued autoregressive (INAR) models. However, when modeling with integer-valued autoregressive processes, the distributional properties of forecasts have been not yet discovered due to the difficulty in handling the Steutal Van Ham thinning operator 'o' (Steutal and van Ham, 1979). In this study, we derive the mean squared error of h-step-ahead prediction from a Poisson INAR(1) process, reflecting the effect of the variability of parameter estimates in the prediction mean squared error.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.864-868
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• 1988

During the 1980s, the use of high-speed printing and copying machines which will not tolerate much variation in paper weight has increased. As a result, there is a growing demand for improved basis weight control systems for paper machines. Basis weight, the weight of a square meter sheet of paper, is the most important measure of paper consistency. Until quite recently, basis weight could only be controlled manually; this required experienced operators. The reasons for the difficulty in automating control of basis weight is due to the complexity and variability of process characteristics, the "noisiness" of the process (process disturbances), and actuator inadequacies. This paper describes a method of automatic control that we have developed; it incorporates the experience of expert operators, and the results of simulation, in confidence factors.e factors.

• Journal of Korean Society for Quality Management
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• v.40 no.3
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• pp.337-346
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• 2012

Purpose: A Control chart is one of the important statistical process control tools that can improve processes by reducing variability and defects. Methods: In the present study, we propose the local $T^2$ multivariate control chart that can efficiently detect abnormal observations by considering the local pattern of the in-control observations. Results: A simulation study has been conducted to examine the property of the proposed control chart and compare it with existing multivariate control charts. Conclusion: The results demonstrate the usefulness and effectiveness of the proposed control chart.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.1-9
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• 2012

Decisions on reliability screening rules and burn-in policies are determined based on the estimated reliability. The variability in a semiconductor manufacturing process does not only causes quality problems but it also makes reliability estimation more complicated. This study investigates the nonuniformity characteristics of integrated circuit reliability according to defect density distribution within a wafer and between wafers then develops optimal burn-in policy based on the estimated reliability. New reliability estimation model based on yield information is developed using a spatial stochastic process. Spatial defect density variation is reflected in the reliability estimation, and the defect densities of each die location are considered as input variables of the burn-in optimization. Reliability screening and optimal burn-in policy subject to the burn-in cost minimization is examined, and numerical experiments are conducted.

• Journal of Korean Institute of Industrial Engineers
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• v.31 no.2
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• pp.164-172
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• 2005

A loss function approach to a multiresponse problem is considered, when process parameters are regarded as random variables. The variation of each response may be amplified through so called propagation of error (POE), which is defined as the standard deviation of the transmitted variability in the response as a function of process parameters. The forms of POE for each response and for a pair of responses are proposed and they are reflected in our loss function approach to determine the optimal condition. The proposed method is illustrated using a polymer case. The result is compared with the case where parameter fluctuation is not considered.

• Korean Journal of Child Studies
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• v.27 no.6
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• pp.199-215
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• 2006

In this study of the documentation process, a toddler's behavior was interpreted through use of text and picture both of which are subjective representations of reality. Two teachers deconstructed and reconstructed their knowledge of a photographed toddler by first referring to scientific theories from a text. They used these theories to analyze markings drawn on paper by the toddler in the photograph. But, the theories from the text were transformed into a new theory in the documentation process of reflecting on the history of markings in different contexts. Thus, the semiotics of pictures and texts changed in addition to change in meanings. This demonstrates the variability of signs, as in the concept of "rhizome" (Deleuze and Guattari, 1999).

• Journal of the Society of Naval Architects of Korea
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• v.41 no.5
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• pp.55-62
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• 2004

The logistics of entire shipbuilding process are integrated during the block erection process and the schedules for the erection process are made prior to. the schedules of any other processes. Therefore, efficient scheduling of the block erection process are one of most important issues in shipbuilding. There are only a few studies published regarding block erection scheduling methods because of its complexity and variability. This paper proposes an algorithm for diminution of maximum load based on constraint satisfaction technique. it is developed primarily for the efficiency in load leveling and applicability to the actual block erection process. The proposed algorithm is applied to actual block erection process and the results shows improvements in load leveling. It can also be used for the scheduling of fabrication, sub-assembly, and assembly to improve load leveling.