• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.947-951
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• 1997

Recently, the necessity of the detection of abnormal machining process is being emphasized in order to improve the machining accuracy and reduce the cost in unmanned operating system. The vibration by chatter generated in cutting processes within machine tools is a relative motion between tools and workpieces. So, if the chatter occurs, the surface roughness and accuracy of workpieces will be deteriorate and it leads to the rapid wear of tools. The author intended to use the I /sab/RMS (current of root mean square) of current sigals and the movimg C.V. (coefficient of variation) of each phase for the detection method of chatter.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.4 no.1
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• pp.1-12
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• 2006

This study conducted RIII reflex measurement to examine degree of pain depending on polarity of high voltage pulsed current of primary and secondary hyperalgesia site in hyperalgesia rat by local thermal injury. Hind paw which was injury site was taken as primary hyperalgeisa site, sole which was injury adjacent site was taken as secondary hyperalgesia site, and mechanical pain threshold, thermal pain threshold and root mean square of RIII reflex were measured. This study was conducted with control group I of hyperalgesia rat at hind paw by thermal injury and experimental groups divided into cathodal high voltage treatment group II, anodal high voltage treatment group III and alternate high voltage treatment group IV, applied active electrode of high voltage pulsed current to hind paw directly, placed reference electrode on the sole of injury adjacent site and applied pulse frequency. It measured RIII reflex and obtained the following results: Root mean square of RIII reflex at primary hyperalgeisa site was significantly reduced in group II after 2 days of hyperalgesia. Group II showed significant decrease after 5 and 6 days of hyperalgesia. Root mean square of RIII reflex at secondary hyperalgesia site showed significant reduction in group II after 6 days of hyperalgesia. Consequently it was found that application of high voltage pulsed current of hyperalgesia site reduced RIII reflex at primary hyperalgeisa site and secondary hyperalgesia site by electrical stimuli. Effects by polarity of high voltage pulsed current showed the greatest reduction of pain threshold when cathodal active electrode was used.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.2
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• pp.190-199
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• 2014

In the last years, fault problem in power electronics has been more and more investigated both from theoretical and practical point of view. The fault problem can cause equipment failure, data and economical losses. And the analyze system require to ensure fault problem and also rectify failures. The current errors on these faults are applied for identified type of faults. This paper presents technique to detection and identification faults in three-phase voltage source inverter (VSI) by using time-frequency distribution (TFD). TFD capable represent time frequency representation (TFR) in temporal and spectral information. Based on TFR, signal parameters are calculated such as instantaneous average current, instantaneous root mean square current, instantaneous fundamental root mean square current and, instantaneous total current waveform distortion. From on results, the detection of VSI faults could be determined based on characteristic of parameter estimation. And also concluded that the fault detection is capable of identifying the type of inverter fault and can reduce cost maintenance.

• The Korean Journal of Applied Statistics
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• v.16 no.1
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• pp.1-14
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• 2003

In this study, we suggest the method of small area estimation based on the Economically Active Population Survey (EAPS) data in producing unemployment statistics for the local self-government areas (LSGAs) within large areas. The small area estimators considered are design-based indirect estimators such as the synthetic and composite estimators. The jackknife mean square error was used as a measure of accuracy of such small area estimators. The total unemployed and jackknife mean square errors of the 10 LSGAs within the large area of ChoongBuk region are derived from the estimation procedure suggested in this study, using EAPS data of December 2000. The reliability of small area estimators was assessed using the relative bias values and relative root mean square errors of these estimators. We find that under the current Korean EAPS system, the composite estimator turns out to be much more stable than other estimators.

• Journal of Environmental Science International
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• v.22 no.5
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• pp.581-589
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• 2013

Surface Image Velocimetry(SIV) is an instrument to measure water surface velocity by using image processing techniques. Since SIV is a non-contact type measurement method, it is very effective and useful to measure water surface velocity for steep mountainous streams, such as streams in Jeju island. In the present study, a surface imaging velocimetry system was used to calculate the flow rate for flood event due to a typhoon. At the same time, two types of electromagnetic surface velocimetries (electromagnetic surface current meter and Kalesto) were used to observe flow velocities and compare the accuracies of each instrument. The comparison showed that for velocity distributions root mean square error(RMSE) was 0.33 and R-squared was 0.72. For discharge measurements, root mean square error(RMSE) reached 6.04 and R-squared did 0.92. It means that surface image velocimetry could be used as an alternative method for electromagnetic surface velocimetries in measuring flood discharge.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.481-486
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• 1997

The interfacial shear stress is experimentally investigated for co-current air-water stratified flow in inclined rectangular channels having a length of 1854mm, width of 120mm and height of 40mm at almost atmospheric pressure. Experiments are carried out in several inclinations from $0^{\circ}\;up\;to\;10^{\circ}$. The local film thickness and the wave height are measured at three locations, i.e., L/H = 8,23, and 40. According to the inclination angle, the experimental data are categorized into two groups; nearly horizontal data group ($0^{\circ}\;{\leq}\;{\theta}\;{\leq}\;0.7^{\circ}$), and inclined channel data group ($0.7^{\circ}\;{\leq}\;{\theta}\;{\leq}\;10^{\circ}$). Experimental observations for nearly horizontal data group show that the flow is not fully developed due to the water level gradient and the hydraulic jump within the channel. For the inclined channel data group, a dimensionless wave height, $\Delta$h/h, is empirically correlated in terms of $Re_{G}$ and h/H. A modified root-mean-square wave height is proposed to consider the effects of the interfacial and wave propagation velocities. It is found that an equivalent roughness has a linear relationship with the modified root-mean-square wave height and its relationship is independent of the inclination.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.11
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• pp.68-76
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• 2014

This paper presents an offset error compensation algorithm for the accurate phase angle of the grid voltage in single-phase grid-connected inverters. The offset error generated from the grid voltage measurement process cause the fundamental harmonic component with grid frequency in the synchronous reference frame phase lock loop (PLL). As a result, the grid angle is distorted and the power quality in power systems is degraded. In addition, the dq-axis currents in the synchronous reference frame and phase current have the dc component, first and second order ripples compared with the grid frequency under the distorted grid angle. In this paper, the effects of the offset and scaling errors are analyzed based on the synchronous reference frame PLL. Particularly, the offset error can be estimated from the integrator output of the synchronous reference frame PLL and compensated by using proportional-integral controller. Moreover, the RMS (Root Mean Square) function is proposed to detect the offset error component. The effectiveness of the proposed algorithm is verified through simulation and experiment results.

• Journal of Korea Multimedia Society
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• v.6 no.5
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• pp.788-796
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• 2003

This paper proposes using dynamic momentum for squential learning method. Using The dynamic momentum improves convergence speed and performance by the variable momentum, also can identify it in the RMSE(root mean squared error). The proposed method is reflected using variable momentum according to current state. While static momentum is equally influenced on the whole, dynamic momentum algorithm can control the convergence rate and performance. According to the variable change of momentum by training. Unlike former classification and regression problems, this paper confirms both performance and regression rate of the dynamic momentum. Using RMSE(root mean square error ), which is one of the regression methods. The proposed dynamic momentum has been applied to the kernel adatron and kernel relaxation as the new sequential learning method of support vector machine presented recently. In order to show the efficiency of the proposed algorithm, SONAR data, the neural network classifier standard evaluation data, are used. The simulation result using the dynamic momentum has a better convergence rate, performance and RMSE than those using the static moment, respectively.

• ETRI Journal
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• v.35 no.3
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• pp.431-438
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• 2013

This paper presents a new realization of the implicit root-mean-square (RMS) detector, employing three second-generation current conveyors and MOS transistors. The proposed circuit can be applied in measuring the RMS value of complex, periodic signals, represented in the form of the Fourier series. To verify the theoretical analysis, circuit Simulation Program with Integrated Circuit Emphasis simulations and experiment results are included, showing agreement with the theory.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1769-1774
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• 2009

An algorithm for extracting the BJT DC model parameter values for SPICE model is proposed. The nonlinear optimization method for analyzing the device I-V data using the Levenberg-Marquardt algorithm is proposed and the method for calculating initial conditions of model parameters to improve the convergence characteristics is proposed. The base current and collector current obtained from the proposed method shows the root mean square error of 6.04% compared with the measured data of the PNP BJT named 2SA1980.