• Journal of the military operations research society of Korea
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• v.27 no.1
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• pp.101-113
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• 2001

Taguchi and VTA(variation Transmission Analysis) methods have been widely used recently as new methods for product design. In this study, Taguchi method using analysis of variance and VTA method using regression analysis are reviewed and compared with each other in terms of parameter design and tolerance design. In analysis of variance, variation of quality characteristics arises from noise factors, therefore the optimal levels of design factors are selected to minimize the effect of noise factors. n regression analysis, variation of quality characteristics arises from variation of each own design factors. As a method to reduce variation of these quality characteristics, sensitivity analysis was performed for each design factors. An example of calculating tolerance interval for the given defect rate in PPM is also introduced. Especially, the new method is suggested to increase the estimation accuracy of variation of quality characteristics through regression analysis.

• International Journal of Quality Innovation
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• v.6 no.1
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• pp.109-118
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• 2005

The parameter design is the most emphasized measure by researchers for a new products development. It is critical for makers to achieve simultaneously in both the time-to-market production and the quality enhancement. However, there are difficulties in practical application, such as (1) complexity and nonlinear relationships co-existed among the system's inputs, outputs and control parameters, (2) interactions occurred among parameters, (3) where the adjustment factors of Taguchi's two-phase optimization procedure cannot be sure to exist in practice, and (4) for some reasons, the data became lost or were never available. For these incomplete data, the Taguchi methods cannot treat them well. Neural networks have a learning capability of fault tolerance and model free characteristics. These characteristics support the neural networks as a competitive tool in processing multivariable input-output implementation. The successful fields include diagnostics, robotics, scheduling, decision-making, prediction, etc. This research is a case study of spherical annealing model. In the beginning, an original model is used to pre-fix a model of parameter design. Then neural networks are introduced to achieve another model. Study results showed both of them could perform the highest spherical level of quality.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1822-1828
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• 2008

This paper presents design parameter calculation methodology and its realization to construction for the 10/350${\mu}s$ lightning impulse current generator(ICG) modelled as double exponential function waveform with characteristic parameters ${\alpha},{\beta}$. Matlab internal function, "fzero" was applied to find ${\lambda}={\alpha}/{\beta}$ which is solution of nonlinear equation linearly related with two wave parameter $T_1$ and $T_2$. The calculation results for 10/350${\mu}s$ lightning impulse current show very good accuracy with error less 0.03%. Two type of 10/350${\mu}s$ ICGs based on the calculated design circuit parameters were fabricated by considering the load variation. One is applicable to the MOV based Surge protective device(SPD) for less 15 kA and the other is to test small resistive devices such as spark gap arrester and bonding device with maximum current capability 30 kA. The tested waveforms show error within 10% in comparison with the designed estimation and the waveform tolerance recommended in the IEC 61643-1 and IEC 60060-1.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.645-651
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• 2002

we propose a k-nearest neighbors(k-NN) based pattern selection method. The method tries to select the patterns that are near the decision boundary and that are correctly labeled. The simulations over synthetic data sets showed promising results: (1) By converting a non-separable problem to a separable one, the search for an optimal error tolerance parameter became unnecessary. (2) SVM training time decreased by two orders of magnitude without any loss of accuracy. (3) The redundant SVM were substantially reduced.

• Korean Journal of Computational Design and Engineering
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• v.15 no.4
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• pp.253-260
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• 2010

This paper presents algorithms for computing offsets of freeform curves. The approach first divides the original curve into several segments at the inflexion points. Based on the obtained new control polygon and its offsets, quadratic trigonometric splines are constructed to approximate the offset curves. Finally, the shape parameter value of trigonometric spline is determined to satisfy the required tolerance. The degree of the output curve is two, independent of the original curve's degree. Because of the great controllability, the proposed method can generate a completely overestimating offset curve by adjusting the value of the shape parameter, which guarantees no overcutting in NC machining. Furthermore, it also produces the lowest number of control points compared with other works.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.89-94
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• 2006

In this paper, the effects of the system parameters on the high cycle fatigue life based on structural dynamic analysis of a turbine blade are investigated. Conventional studies have forcused on the fatigue life of turbine blades with specific system parameters. However, each parameter has statistical deviation because of inhomogeneity of material property, tolerance, and operating conditions. Therefore a methodology that estimates the effects of system parameter on the fatigue lift deviation is demonstrated.

• Journal of Biomedical Engineering Research
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• v.2 no.1
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• pp.31-38
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• 1981

The objective of the present study was to develop an equivalent circuit model of glucose kinetics including the hepatic glucose balance functions which were neglected in the previous compartmental models. Using this circuit model, the insulin resistivity parameter and hepatic glucose sensitivity parameter were estimated in optimal fitting of the model based data of glucose and insulin concentration to the reported clinical intravenous glucose tolerance test(IVGTT) data in normal and diabetic subjects. The addition of the hepatic function in the model has improved the overall performance of the simulation. Also, the computed tissue insulin resistivity and the hepatic glucose sensitivity are shown to be significant in distinguishin four clinical groups of normal and diabetic groups.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.2
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• pp.296-303
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• 2001

Kachanov-Rabotnov(K-R) creep damage theory was reviewed, and applied to design a creep curve for type 316LN stainless steel. Seven coefficients used in the theory, i.e., A, B, k, m, λ, r, and q were determined, and their physical meanings were analyzed clearly. In order to quantify a damage parameter ($\omega$), cavity amount was measured in the crept specimen taken from interrupted creep test with time variation, and then the amount was reflected into K-R damage equations. Coefficient λ, which is regarded as a creep tolerance feature of a material, increased with creep strain. Mater curve with λ=2.8 was well coincided with an experimental one to the full lifetime. The relationship between damage parameter and life fraction was matched with the theory at exponent ${\gamma}$=24 value. It is concluded that K-R damage equation was reliable as the modelling equation for type 316LN stainless steel. Coefficient data obtained from type 316LN stainless steel can be utilized for life prediction of operating material.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1945-1955
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• 2018

High frequency signal injection (HFI) is an alternative method for estimating rotor position of interior permanent magnet synchronous motor (IPMSM). The general method of frequency and amplitude selection is based on error tolerance and experiments, and is usually set with only one group of HF parameters, which is not efficient for different working modes. This paper proposes a novel rotor position estimation scheme by HFI with optimized frequency and amplitude, based on the mathematic model of IPMSM. The requirements for standstill and low-speed operational modes are met by applying this novel scheme. Additionally, the effects of the frequency and amplitude of the injected HF signal on the position estimation results under different operating conditions are analyzed. Furthermore, an optimization method for HF parameter selection is proposed to make the estimation process more efficient under different working conditions according to error tolerance. The effectiveness of the propose scheme is verified by the experiments on an IPMSM motor prototype.

• Journal of radiological science and technology
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• v.45 no.6
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• pp.491-502
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• 2022

The purpose of this study was to retrospectively investigate the upper and lower control limits of treatment planning parameters using EBT film based delivery quality assurance (DQA) results and to analyze the results of statistical process control (SPC) in helical tomotherapy (HT). A total of 152 patients who passed or failed DQA results were retrospectively included in this study. Prostate (n = 66), rectal (n = 51), and large-field cancer patients, including lymph nodes (n = 35), were randomly selected. The absolute point dose difference (DD) and global gamma passing rate (GPR) were analyzed for all patients. Control charts were used to evaluate the upper and lower control limits (UCL and LCL) for all the assessed treatment planning parameters. Treatment planning parameters such as gantry period, leaf open time (LOT), pitch, field width, actual and planning modulation factor, treatment time, couch speed, and couch travel were analyzed to provide the optimal range using the DQA results. The classification and regression tree (CART) was used to predict the relative importance of variables in the DQA results from various treatment planning parameters. We confirmed that the proportion of patients with an LOT below 100 ms in the failure group was relatively higher than that in the passing group. SPC can detect QA failure prior to over dosimetric QA tolerance levels. The acceptable tolerance range of each planning parameter may assist in the prediction of DQA failures using the SPC tool in the future.