• Journal of Korean Society for Quality Management
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• v.26 no.4
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• pp.88-100
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• 1998

Robust design in industry is an a, pp.oach to reducing performance variation of quality characteristic value in products and processes. Taguchi has used the signal-to-noise raio(SN) to achieve the a, pp.opriate set of operating conditions where variablity around target is low in the Taguchi parameter design. Taguchi has dealt with having constraints on both the mean and variability of a characteristic (the dual response problem) by combining information on both mean and variability into an SN. Many Statisticians criticize the Taguchi techniques of analysis, particularly those based on the SN. In this paper we propose a substantially simpler optimization procedure for robust design to solve the dual response problems without resorting to SN. Two examples illustrate this procedure in the two different experimental design(product array, combined array) a, pp.oaches.

• Journal of Environmental Science International
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• v.18 no.10
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• pp.1155-1162
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• 2009

To investigate the influence of water area calmness on the red tide development, runoff phenomena due to antecedent precipitation of red tide development day were analyzed. There were examined the water quality variation properties at about the same time of the red tide develop. The red tide was developed when the stage and discharge nearly had not changed. It was estimated that the stability of particle behavior in the mouth of river effected on the red tide develop. Also, the concentrations of $COD_{Mn}$ were increased about 241~629% when the red tide developed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.108-111
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• 2007

It's important to measure quantitative properties about thermal-nano variation conduct of polymer for producing high quality components using NIL process. NanoScale indents can be used ad cells for molecular electronics and drug deliver, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, it's to evaluate mechanical characteristic of polymer such as PMMA and PC at high temperature for manufacture of nano/micro size of polymer using indenter at high temperature. At high temperature mechanical properties of polymer have extreme variation. Because heating the polymer, it becomes softer than room temperature. In this case it is especially important to study for mechanical properties of polymer at high temperature.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1281-1289
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• 2002

This study was conducted to evaluate water quality in the Keum River using multivariate analysis. The analysis data in Keum river made use of surveyed data by the ministry of environment from January 1994 to December 2001. Thirteen water quality parameter were determined on each sample. The results was summarized as follow; Water quality in the Keum River could be explained up to 71.39% by four factors which were included in loading of organic matter and nutrients by the tributaries (32.88%), seasonal variation (16.09%), loading of pathogenic bacteria by domestic sewage of Gapcheon (13.39%) and internal metabolism in estuary as lakes(9.03%). For spatial variation of factor score, four group was classified by each factor characterization. Station 1 and 2 was influenced by Daechung dam, station 3 was affected by domestic sewage of Gapcheon, station 10~12 was affected by estuary dyke and the rest station. The result of cluster analysis by station was classified into four group that has different water quality characteristics. In monthly cluster analysis, three group was classified according to seasonal characteristic. Also, in yearly cluster analysis, three group was classified. It is necessary to control the pollutant loadings by Gapcheon inflow domestic sewage in Daejeon city for the sake of water quality management of Keum river.

• Journal of Korean Society for Quality Management
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• v.38 no.1
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• pp.96-100
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• 2010

The shelf-life of pharmaceutical products is the time that the average product characteristic remains within an approved specification after manufacture. Since the true shelf-life of a drug product is typically unknown, it has to be estimated based on assay results of the drug characteristic from a stability study usually conducted during the process of drug development. The nonparametric statistical methods of assessing the shelf-life of drug are considered with the current FDA regulations. Some simulation studies of nonparametric methods are also presented with the discussion.

• Journal of Integrative Natural Science
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• v.11 no.2
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• pp.76-81
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• 2018

Robust design is an approach to reducing performance variation of quality characteristic values in quality engineering. Product array approach which is used in the Taguchi parameter design has a number of advantages by considering the noise factor. Taguchi has an idea that mean and variation are handled simultaneously to reduce the expected loss in products and processes. Taguchi has used the signal-to-noise ratio (SN) to achieve the appropriate set of operating conditions where variability around target is low in the Taguchi parameter design. Many Statisticians criticize the Taguchi techniques of analysis, particularly those based on the SN. In this paper we propose a substantially simpler optimization procedure for robust design using desirability function without resorting to SN.

• Journal of Applied Reliability
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• v.1 no.1
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• pp.35-46
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• 2001

Replacement policy of a degradation system is investigated by incorporating the loss function. Loss function is defined by the deviation of the value of quality characteristic from its target value, which determines the loss cost. Cost function is comprised of the inspection cost, replacement cost and loss cost. Two cost minimization problems are formulated : 1)determination of an optimal inspection period given the state for the replacement and 2)determination of an optimal state for replacement under fixed inspection period. Simulation analysis is performed to observe the variation of total cost with respect to the variation of the parameters of loss function and inspection cost, respectively As a result, parameters of loss function are seen to be the most sensitive to the total cost. On the contrary, inspection cost is observed to be insensitive. This study can be applied to the replacement policy of a degradation system which has to produce the quality critical product.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.3
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• pp.52-60
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• 1993

Fluttering ghost which is the most severs picture impairment in mobile TV reception under multipath fading environments can be detected by measuring the dynamic variation of the synchronizing pulse timing. And also, the occurrence-stucture of fluttering ghost are directly correlated with the multipath parameters. This paper describes the quantitative evaluating method of the mobile TV pictures impaired by multipath parameters by means of the spectral analysis of synchronizing timing fluctuation. The ghost-flutter curve derived from the spatial amplitue spectrum of synchronizing pulse timing fluctuation express well the spatial variation characteristic, and it has been found to be the quantitative evaluating measure of picture impairment in mobile reception. A correspondence between the ghost-flutter curve (and/or index) and picture quality opinion test results is established.

• Journal of Environmental Science International
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• v.15 no.11
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• pp.1017-1025
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• 2006

This study was conducted to evaluate characteristic of water duality in coastal sea of Incheon using a multivariate analysis. The analysis data in coastal sea of Incheon was aquired by the NFRDI data which was surveyed from March 1997 to November 2003. Eleven water quality parameters were determined on each survey The results were summarized as follow : Water quality in Incheon coastal sea could be explained up to 64.62% by three factors which were included in loading of fresh water and nutrients by the land(36.98%), seasonal variation(16.19%), and internal metabolism (11.24%). The results of time series analysis by factor score, in case of factor 1, station 1 influenced by Han river was shown to high factor score and station 3 located by outer sea was shown to low factor score. In case of factor 2, station 1 was appeared to high variation and station 3 was appeared to low variation. The result of cluster analysis by station was classified into three group that has different water quality characteristics. Especially, station 1 which affected by Han river and station 4 which affected by sewage treatment plant was appeared to considerable water quality characteristics against other station. In yearly cluster analysis, three group was classified and water quality in 2003 years due to high precipitation was different to another year. It could be suggested from these results that it is important to control discharge of fresh water by Han rivet and sewage treatment plant for water quality management of coastal sea of Incheon.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.10
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• pp.975-979
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• 2010

Existing quality adaptation schemes are useful for improving network stability in a congested network, but these schemes do not guarantee the quality of experience on video streaming due to the frequent variations in playback quality for a streaming service. In this paper, we propose a network-adaptive quality adaptation scheme to guarantee the quality of experience on SVC(Scalable Video Coding) video streaming. The proposed scheme estimates the available bandwidth by bandwidth measurement scheme using media characteristic, and then smoothly adjusts the quality level of SVC video stream according to the estimated bandwidth. Through the simulation, we prove that our scheme guarantees the quality of experience for video streaming by minimizing quality variation.