• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.52
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• pp.347-354
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• 1999

Statistical Process Control(SPC) which uses control charts is widely used to inspect and improve manufacturing process as a effective method. A parametric method is the most common in statistical process control. Shewhart chart was made under the assumption that measurements are independent and normal distribution. In practice, this assumption is often excluded, for example, in case of (equation omitted) chart, when the subgroup sample is small or correlation, it happens that measured data have bias or rejection of the normality test. A bootstrap method can be used in such a situation, which is calculated by resampling procedure without pre-distribution assumption. In this study, applying bootstrap percentile method to (equation omitted) chart, it is compared and evaluated standard process control limit with bootstrap percentile control limit. Also, under the normal and non-normal distributions, where parameter is 0.5, using computer simulation, it is compared standard parametric with bootstrap method which is used to decide process control limits in process quality.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.5
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• pp.1388-1399
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• 2012

This paper proposes a quality metric based on a No-Reference Bitstream (NR-B) having least computational complexity for the assessment of the human-perceptual quality of H.264 encoded video. The proposed NR-B method performs a modeling of encoding distortion with three bit-stream information (i.e. frame-rate, motion-vector, and quantization-parameter) that can be directly extractable from the encoded bitstream and does not require additional complex processing of final pictures. From performance evaluation using 165 compressed video sequences, the experiment results show that the proposed metric has a higher correlation with subjective quality than is achieved with other comparable methods.

• Restorative Dentistry and Endodontics
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• v.41 no.4
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• pp.239-245
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• 2016

The purpose of this article was to review the changes in translucency of direct esthetic restorative materials after curing, aging and treatment. As a criterion for the evaluation of clinical translucency changes, visual perceptibility threshold in translucency parameter difference (${\Delta}TP$) of 2 was used. Translucency changes after curing were perceivable depending on experimental methods and products (largest ${\Delta}TP$ in resin composites = 15.9). Translucency changes after aging were reported as either relatively stable or showed perceivable changes by aging protocols (largest ${\Delta}TP$ in resin composites = -3.8). Translucency changes after curing, aging and treatment were perceivable in several products and experimental methods. Therefore, shade matching of direct esthetic materials should be performed considering these instabilities of translucency in direct esthetic materials.

• Communications for Statistical Applications and Methods
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• v.25 no.6
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• pp.605-618
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• 2018

Risk management has been a crucial part of the daily operations of the financial industry over the past two decades. Value at Risk (VaR), a quantitative measure introduced by JP Morgan in 1995, is the most popular and simplest quantitative measure of risk. VaR has been widely applied to the risk evaluation over all types of financial activities, including portfolio management and asset allocation. This paper uses the implementations of multivariate GARCH models and copula methods to illustrate the performance of a one-day-ahead VaR prediction modeling process for high-dimensional portfolios. Many factors, such as the interaction among included assets, are included in the modeling process. Additionally, empirical data analyses and backtesting results are demonstrated through a rolling analysis, which help capture the instability of parameter estimates. We find that our way of modeling is relatively robust and flexible.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.165-168
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• 1995

The quality of products is depend on the performance of machine and machining conditions. In this study the runout of spindel is selected as a parameter through which we could appreciate the workability of machine and the quality of products. Throigh the runout of high speed machining center on freeload machining, the revolution accuracy and the characteristics in connection with spindle speed are evaluated. It was experimented flat and ball end milling for estimating machine accuracy and workability by measuring spindel runout. In end, This paper shows the effects of runout on surface roughness through analysis of runout and roughness profiles.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.170-179
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• 2004

A vibration model of powder transfer equipment is developed by the lumped parameter method. A Powder transfer equipment does surging motion, bouncing motion and pitching motion. Motion equation becomes decoupling and removed vibration exciting source about pitching motion, and therefore designers presented the optimum design plan to be able to do adjustment with motion trajectory of powder transfer equipment. That is, way for design to be able to do motion trajectory of powder transfer equipment through change of design element as installation position and direction of motor, driving speed, mass unbalance, stiffness coefficient and installation position of support coil spring is presented. The design results, powder transfer equipment were able to know that fatigue destruction does not occur, and the reason is because maximum stress working on a basket structure is more very than fatigue strength small.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.4
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• pp.118-127
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• 1998

In this paper, we propose a voice personality transformation method which makes one person's voice sound like another person's voice. In order to transform the voice personality, vocal tract transfer function is used as a transformation parameter. Comparing with previous methods, the proposed method can obtain high-quality transformed speech with low computational complexity. Conversion between the vocal tract transfer functions is implemented by a linear mapping based on soft clustering. In this process, mean LPC cepstrum coefficients and mean removed LPC cepstrum modeled by the low dimensional vector are used as transformation parameters. To evaluate the performance of the proposed method, mapping rules are generated from 61 Korean words uttered by two male and one female speakers. These rules are then applied to 9 sentences uttered by the same persons, and objective evaluation and subjective listening tests for the transformed speech are performed.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.4
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• pp.443-453
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• 2002

Many firms are trying to optimize their production and distribution systems separately, but possible profit increase by this approach is limited. Nowadays, it is more important to analyze these two systems simultaneously for the integrated supply chain management. This paper is a computational study to investigate the effectiveness of integrating production and distribution scheduling. We are interested in a multi-plant, multi-retailer, multi-product and multi-period industrial problem where the objective in solving production and distribution scheduling problem is to maximize the total net profit. Computational results on test problems of various sizes using the heuristic we developed show a substantial advantage of the integrated scheduling approach over the decoupled scheduling process. Sensitivity analysis on the parameter values indicates that, under the right conditions, the effectiveness of integrating production and distribution functions can be extremely high.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.4
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• pp.35-41
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• 2008

R/In order to satisfy the customer's variant needs for a product quality in recent years, a demand for developing higher precision machining technologies in a lot of application areas such as automobile, cellular phone and semiconductor has been increased more and more. Magnetic abrasive polishing(MAP) process is one of these precision technologies. In this study, to verify the parameters' effect of the MAP process on the surface roughness improvement of the plane and the inclined workpiece, well planned experiments which was called the design of experiments were carried out. Considered polishing factors were spindle speed, supplied current, abrasive type and working gap between the workpiece and the solid tool. As a result, it was seen that the supplied current and the working gap greatly affected the surface roughness improvement.

• Journal of Applied Reliability
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• v.7 no.3
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• pp.111-118
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• 2007

In 2000, US Army Test and Evaluation Command (ATEC) released the status of reliability requirement levels and achievements for the military equipment which evaluated through the operational tests from 1985 to 1990 and from 1996 to 2000. The rates of military equipments that do not meet reliability requirements are 59% from 1985 to 1990 and 80% from 1996 to 2000. Thus, the US Army has figured out causes, taken steps and put them into practice, This paper is about the recent reliability problems and the latest tendency about US military equipment to acquirere liability level.