• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.49 no.8
• /
• pp.451-458
• /
• 2000

The precise speed and position control technique for Brushless DC Motor demands accurate position and speed feedback information. Generally, resolver or absolute encoders are used as speed and positiion sensor. But they increase cost and more problem happens at low speed than high speed specially. Therefore, in this paper, optimal speed observer is proposed for decreasing size and cost of whole system. And also, we consider the error problem about the system modeling and measurement at low speed range as well as high speed. The overall system consists of two parts, a drive and a speed observer. We make use of Least square curve fitting algorithm as speed observer and can overcome low resolution by proposed observer. Also, because of using the signal of hall sensor, robust control is possible in low speed as well as high speed for the change of the parameters of the system and disturbance. To construct observer using the signal of hall sensor, we design the pulse multiplier circuit and the software of microprocessor, AT89CC2051. Finally, the performance of the proposed observer is exemplified by some simulations and experiments.

• International Journal of Automotive Technology
• /
• v.6 no.2
• /
• pp.141-148
• /
• 2005

In order to reduce the time and costs of improving the performance of vehicle suspensions, the techniques for optimizing damping and air spring characteristic were proposed. A full vehicle model for a bus is constructed with a car body, front and rear suspension linkages, air springs, dampers, tires, and a steering system. An air spring and a damper are modeled with nonlinear characteristics using experimental data and a curve fitting technique. The objective function for ride quality is WRMS (Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. The objective function for handling performance is the RMS (Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a lane change. The design variables are determined by damping coefficients, damping exponents and curve fitting parameters of air spring characteristic curves. The Taguchi method is used in order to investigate sensitivity of design variables. Since ride and handling performances are mutually conflicting characteristics, the validity of the developed optimum design procedure is demonstrated by comparing the trends of ride and handling performance indices with respect to the ratio of weighting factors. The global criterion method is proposed to obtain the solution of multi-objective optimization problem.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.6
• /
• pp.471-480
• /
• 2022

Inductive power transfer (IPT) is an attractive power transmission solution that is already used in many applications. In the IPT system, optimal coil design is essential to achieve high power efficiency, but the effective design method is yet to be investigated. The inductance formula and finite element method (FEM) are popular means to link the coil geometric parameters and circuit parameters; however, the former lacks generality and accuracy, and the latter consumes much computation time. This study proposes a novel coil design method to achieve speed and generality without much loss of accuracy. By introducing one-turn permeance simulation in each FEM phase combined with curve fitting and optimization by MATLAB in the efficiency calculation phase, the iteration number of FEM can be considerably reduced, and the generality can be retained. The proposed method is verified through a 100 W IPT system experiment.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.276-277
• /
• 2006

Estimation of power system frequency is an important task because frequency deviation is a good indicator of the system abnormal operating conditions. The algorithms, curve fitting, technique using Taylor series, deviation of phasor angle of fundamental waveform using DFT (Discrete Fourier Transform) and Prony method, are tested under operation of the frequency relaying by using EMTP MODELS. The performance of methods is compared with the simulation results.

• 한국전산유체공학회:학술대회논문집
• /
• 1999.05a
• /
• pp.23-28
• /
• 1999

A mutigrid convergence acceleration technique is presented for computing hypersonic inviscid and viscous flows in equilibrium state. The governing equations are solved using an explicit Runge-Kutta method. Curve fitting data in NASA Reference Publication 1181, 1260 are used to calculate equilibrium properties. In order to ensure stability, damped prolongation and modified implicit residual smoothing are proposed. Blunt body test cases are presented to demonstrate the robustness and the efficiency in performance of the proposed methods

• Food Science and Biotechnology
• /
• v.17 no.6
• /
• pp.1352-1356
• /
• 2008

Bootstrap method, a computer-intensive statistical technique to estimate the distribution of a statistic was applied to deal with uncertainty and variability of the experimental data in stochastic prediction modeling of microbial growth on a chill-stored food. Three different bootstrapping methods for the curve-fitting to the microbial count data were compared in determining the parameters of Baranyi and Roberts growth model: nonlinear regression to static version function with resampling residuals onto all the experimental microbial count data; static version regression onto mean counts at sampling times; dynamic version fitting of differential equations onto the bootstrapped mean counts. All the methods outputted almost same mean values of the parameters with difference in their distribution. Parameter search according to the dynamic form of differential equations resulted in the largest distribution of the model parameters but produced the confidence interval of the predicted microbial count close to those of nonlinear regression of static equation.

• Journal of Computational Design and Engineering
• /
• v.2 no.4
• /
• pp.218-232
• /
• 2015

Piecewise linear (G01-based) tool paths generated by CAM systems lack $G_1$ and $G_2$ continuity. The discontinuity causes vibration and unnecessary hesitation during machining. To ensure efficient high-speed machining, a method to improve the continuity of the tool paths is required, such as B-spline fitting that approximates G01 paths with B-spline curves. Conventional B-spline fitting approaches cannot be directly used for tool path B-spline fitting, because they have shortages such as numerical instability, lack of chord error constraint, and lack of assurance of a usable result. Progressive and Iterative Approximation for Least Squares (LSPIA) is an efficient method for data fitting that solves the numerical instability problem. However, it does not consider chord errors and needs more work to ensure ironclad results for commercial applications. In this paper, we use LSPIA method incorporating Energy term (ELSPIA) to avoid the numerical instability, and lower chord errors by using stretching energy term. We implement several algorithm improvements, including (1) an improved technique for initial control point determination over Dominant Point Method, (2) an algorithm that updates foot point parameters as needed, (3) analysis of the degrees of freedom of control points to insert new control points only when needed, (4) chord error refinement using a similar ELSPIA method with the above enhancements. The proposed approach can generate a shape-preserving B-spline curve. Experiments with data analysis and machining tests are presented for verification of quality and efficiency. Comparisons with other known solutions are included to evaluate the worthiness of the proposed solution.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.2
• /
• pp.542-551
• /
• 2000

In this paper, a novel technique is presented for automatic brain region segmentation in single channel MR image data sets for 3D visualization and analysis. The method detects brain contours in 2D and 3D processing of four steps. The first and the second make a head mask and an initial brain mask by automatic thresholding using a curve fitting technique. The stage 3 reconstructs 3D volume of the initial brain mask by cubic interpolation and generates an intermediate brain mask using morphological operation and labeling of connected components. In the final step, the brain mask is refined by automatic thresholding using curve fitting. This algorithm is useful for fully automatic brain region segmentation of T1-weighted, T2-weighted, PD-weighted, SPGR MRI data sets without considering slice direction and covering a whole volume of a brain. In the experiments, the algorithm was applied to 20 sets of MR images and showed over 0.97 in comparison with manual drawing in similarity index.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.12
• /
• pp.90-97
• /
• 1997

This paper presents a new algorithm for surface segmentation and feature description. The algorithm extracts the signature of an edge image based on the signature technqique[12] in the first stage. If there exists a range in the angle axis where more than two signatures form a closed curve, we can conclude there is a surface inside the range. Using this feature of the signature, surfaces can be segmented. The surface features such as number of vertices, number of edges, and type of surfaces can also be extracted by finding the signatures of individual surfaces. This algorithm has distinguished advantages: it can easily recover the lost part occuring in the edge iage using the curve fitting method and it can extract surface features even when surfaces are rotated in 3-D space.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.30A no.9
• /
• pp.14-23
• /
• 1993

In this paper, we present analysis results of various intermodulation products (IMPs) evaluation methods previously proposed for nonlinear systems. The results indicate that out of these methods, Fuenzalida and Simbo's method is the best for efficient evaluation of IMPs. Also, we present a detailed mathematical analysis of IMP and show how to apply the equations related to IMP to actual program implementations with examples. In this paper, we newly introduce three methods to reduce the IMP calculation time and improve the accuracy of the outputs :1) TWTA curve fitting method by LS (Least Square), 2) IMP evaluation technique which is based on a look-up table 3) Gaussian spectral shaping for PSK signal instead of convolution. The IMP evaluation results obtained by the new approaches introduced in this paper resulted in a good match with the published outputs in the open literature and showed improved performance especially in the TWTA curve .