• The Korean Journal of Applied Statistics
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• v.11 no.1
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• pp.13-28
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• 1998

Corrent measurement system assessment is crucial in helping improve process or quality. In this article, we would like to apply several methods of measurement system assessment in statistical process control. Specifically, focus is on accuracy, precision (both repeatability and reproducibility included), and stability of the measurement process.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.55-63
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• 1999

Past studies on economic control charts for controlling process means assumed that the measures of a quality characteristic do not have measurement error. In practice, however, this assumption is frequently violated. In this paper, the economic design models of three control charts(Xbar control chart, Xbar control chart with warning limits, and CUSUM control chart) for controlling process means are developed on the assumption that the measures can have measurement error. The effects of measurement error on the process control cost and design parameters of three economic control charts are examined. According to the experiments done in this study, when measurement error exists, the economic CUSUM control chart has lower process control cost in comparison with two other control charts. When measurement error becomes larger, both the sample size and the sampling interval increase while the control limits decrease.

• The KIPS Transactions:PartD
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• v.12D no.1 s.97
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• pp.91-102
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• 2005

In the past it was generally felt that software quality was the same as product quality. But as the software industry is getting bigger and more complex, it has become hard to develop quality software that meets customers' needs just depending on product quality. Therefore, lately many domestic and foreign companies are making efforts to upgrade product quality by implementing Process Improvement. Measurement in Process Improvement activities enhances the effect of Process Improvement, and also identifies and helps the activities. In support of this paper, research on the measurement program was conducted based on the CMMI adopted by many domestic and foreign companies for their process improvement model. MA process area that deals with measurement process setup is one of the CMMI process areas and was the basis of the structure of the measurement program. This study presents differences of the measurement program for each level of CMMI and how to apply it. The results of this study can help a business to apply CMMI-based Process Improvement by backing up the structure of the measurement program. Furthermore, it can offer a roadmap for progress of the measurement program for each level.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.53-59
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• 2004

In this paper, we propose a new multi-purpose Scanning Force Microscope (SFM) system. The system can be used for nano/micro-scratching, in-process profile measurement, and observation of potential surface defects which occur during the scratching in air or liquid. Experimental results of nano/micro-scratching show that the smallest scratching depth can be controlled to be 10nm, which corresponds to the stability of the SFM system. Profile measurements of nano/micro-scratching surfaces have also been performed by the method of on-machine measurement and in-process measurement. Two measurement results were in good agreement with each other. The maximum difference was approximately 10 nm, which was mainly caused by the sampling repeatability error that influences the measurement accuracy Also, micro-defects on the micro-scratching surface were successfully detected by the SFM system. It was confirmed that the number of micro-defects increases when the surface is subjected to a cyclic bending load. The maximum depth was less than 100nm.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.51-58
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• 2015

In this study, we developed an automated non-contact thickness measurement machine that continuously and precisely measures the thickness and warp of a PCB product using a laser sensor. The system contains a measurement part to measure the thickness in real time automatically according to the set conditions with an alignment supply unit and unloading unit to separate OK and NG products. The measurement machine was utilized to evaluate the performance at each step to minimize measurement error. At the zero setting for the initial setup, the standard deviation of the 216 samples was determined to be $5.52{\mu}m$. A measurement error of 0.5mm and 1.0mm as a standard sample in the measurement accuracy assessment was found to be 2.48% and 2.28%, respectively. In the factory acceptance test, the standard deviation of 1.461mm PCB was measured as $28.99{\mu}m$, with a $C_{pk}$ of 1.2. The automatic thickness measurement machine developed in this study can contribute to productivity and quality improvement in the mass production process.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.75-84
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• 2003

In this paper, a new nano/micro-mechanical processing test machine was developed. This new test machine, which is based on the principle of the scanning force controlled probe microscope, can realize nano/micro-mechanical machining and in-process profile measurement. Experimental results of nano/micro indentation and scratching show that the controllable cutting depth of the test machine can be controlled by PZT actuator. Profile measurement of the machined surface has also been performed by using the test machine and a conventional AFM(Atomic Force Microscopy). A good agreement of the two measurement results have been achieved.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.2
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• pp.84-92
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• 2004

A process control procedure is proposed when 100% inspection is performed in a process with excellent capability. Only the incomplete measurement data is assumed to be available, i.e. the specific measurement value of the quality characteristic is not available for each item but it can be determined to be smaller or larger than any prescribed value. In the suggested model, a signal limit is introduced to determine whether the process under study is in control or not. If the quality characteristic of an incoming item exceeds the upper signal or the lower signal limit, the process is determined to be stopped or not by comparing the number of consecutively accepted items with a predetermined threshold number. The procedure is designed based on the type I and II errors. The performance of the model is evaluated by the expected number of items produced under the in-control and out-of-control states until the process is stopped.

• Journal of Digital Convergence
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• v.7 no.3
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• pp.61-74
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• 2009

This research reviewed previous research related to Performance Measurement Models of Knowledge Management (PMMKM) in order to integrate their findings with more recent research and construct a new PMMKM. This new hypothetical PMMKM consists of an input sector, a process sector, an outcome sector, and an infrastructure sector. Each sector has three measurement items with the exception of the infrastructure sector which has two. Empirical analyses testing the overall performance model validity of the hypothetical PMMKM were favorable. However, it show be noted that the "share process" and "utilization process" items in the process sector merged into one single item. The same is true with the "individual outcome" and "organization outcome" items in the outcome sector found one single item. The study's results reveal three implications with respect to performance. First, there are derived integrated performance measurement sectors and items based on overall management process of knowledge management, which can be practically applied to the government related research entities. This became apparent after extensive review or previous theoretical studies related to the public sector and private sector. Second, weighted performance measurement of knowledge management using AHP (Analytic Hierarchy Process) Analysis makes it possible to propose PMMKM in government sponsored research institutes. Finally, measuring performance to management knowledge, as shown in this study, will prove useful for inside and outside experts who propose specific guidelines and methodologies for Knowledge management at government sponsored research institutes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.100-106
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• 2017

A universal outer diameter measurement module was developed using a linear variable differential transformer (LVDT). This outer diameter measurement module enables simultaneous measurement of outer diameter, displacement, and perpendicularity of bench-type high-precision products by combining analogue and digital measurement principles with mechanically precise and fine adjustment functions. The developed module showed a performance of 0.001mm in measurement resolution, 0.001mm in measurement accuracy, reference surface abrasion lower than Ra 0.1864, and measurement stability of 0.002mm. Therefore, we have acquired domestic measurement technology to improve productivity by securing technical competitiveness for universal diameter measurement technology, lower production costs through import substitution, and increased quality of products with more precise measurement technology. Furthermore, a substitution effect is expected for expensive import measurement system equipment used in production, research, and inspection sites in industries that produce precision processing products such as automobile and machine components.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.136-144
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• 1999

This paper presents an in-process measurement system for shaft radius measurement during grinding process. This system does not require to stop the grinding process, which can enhance productivity and quality. In order to measure the radius, the system employs an eddy current sensor that can measure without any contact with the shaft. This type of sensor is very appropriate because it is insensitive to interference such as cutting fluid, coolant, contact pressure, and wear. For data analysis, the measurement system is modeled as a linearized discrete form where the states with noise are estimated by an extended Kalman filter. This system has been validated through simulations and experiments.