• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.2
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• pp.112-118
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• 1997

Characteristics of AE(Acoustic Emission) signal is related to cutting conditions, tool materials, and tool geometry in metal cutting. Relation between AE signal and tool wear was investigated experimentally. Experiment is carried out by interrupted cutting for SCM420 workpiece with TiN coating tool on HSS material. AE RMS voltage and count per event were increased according to tool wear. The major results are as follows : 1) AE RMS value is nearly constant as cutting speed changes, but is rapidly increase as feed rate increases. 2) AE RMS value and Count per Event increase as tool wear increases. 3) It is more effective to monitor tool wear by Incremental rate of AE RMS value than by Incremental rate of count per event.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.73-79
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• 2001

The purpose of this investigation is experimentally to clarify the machinability and tool wear of STS 304 steel pipe material for piping. In order to determine the effects of cutting parameters and tool wear on thrust, torque, AE RMS, drilling is conducted on CNC milling machine. In this experiment, it is measured that thrust, torque, tool wear length, tool wear area and AE RMS during drilling using Hss tool. It has been found that a) During the drilling, the thrust and the torque of the STS 304 pipe are received more the effect of the feed than the spindle speed and the thrust increase with the increase of feed, b) The value of the AE RMS is been larger the effect of the cutting speed than the feed rate, and the value of the AE RMS increase with the increase of spindle speed, c) It has been found that the suitable feed in feed condition of 0.03, 0.05, 0.1, 0.15mm/rev is below 0.05mm/rev, d) The value of the AE RMS was shown a characteristic of the jump value during it was a sudden inrcrease of the tool wear. The increased character of the AE RMS value can be known an effective factor of the tool wear detection, and e) It can be quantitatively evaluated the condition of the tool according to calculate a area of the drill wear image which is obtained by a vision system.

• The Transactions of the Korean Institute of Power Electronics
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• v.23 no.6
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• pp.381-388
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• 2018

A novel and simple algorithm for accurate calculation of RMS voltage is proposed in a digitally controlled grid-tie inverter system. Given that the actual frequency of grid voltage is continuously changing, the constant sampling frequency cannot be a multiple number of the fundamental frequency. Therefore, the RMS of grid voltage contains periodic oscillations due to the differences in the phase angle of sampled data during calculation. The proposed algorithm precisely calculates and updates the initial phase angle of the first sampled voltage in a half-cycle period using phase-locked loop, which is commonly utilized for phase angle detection in grid-tie inverter systems. The accuracy and dynamic performance of the proposed algorithm are compared with those of other algorithms through various simulations and experiments.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.1
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• pp.1-5
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• 2012

Purpose : In this study, stroke patients' limits of stability and functional reach test and tibialis anterior, gastrocnemius muscle of lower extremity muscle activities to evaluate the correlation. Methods : 30 adult stroke patients to participate in this study. Limits of stability were measured using biorescue, tibialis anterior and gastrocnemius muscle of muscles activities were measured with functional reach test when there was movement. Results : Limits of stability and functional reach test (r=0.753, p<0.01), RMS value of the limits of stability and tibialis anterior muscle (r=0.706, p<0.01), RMS value of the limits of stability and gastrocnemius muscle (r=0.766, p<0.01), RMS value of the functional reach test and tibialis anterior muscle (r=0.835, p<0.01), RMS value of the functional reach test and gastrocnemius muscle (r=0.663, p<0.01), RMS value of the tibialis anterior and gastrocnemius muscle (r=0.816, p<0.01) correlations are shown as statistically significant. Conclusion : The balance and lower extremity muscle activities of stroke patients were studied, and were positively correlated with the RMS value of the limits of stability and functional reach test, tibialis anterior muscle, and gastrocnemius muscle. This study has shown that stroke patients' ankle joint muscle activity can greatly.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1139-1147
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• 2015

In this paper, an algorithm based on a model analysis of the online calculation of the root-mean-square (RMS) value of welding current for single-phase AC resistance spot welding (RSW) was developed. The current is highly nonlinear and typically non-sinusoidal, which makes the measuring and controlling actions difficult. Though some previous methods focused on this issue, they were so complex that they could not be effectively used in general cases. The electrical model of a single-phase AC RSW was analyzed, and then an algorithm for online calculation of the RMS value of the welding current was presented. The description includes two parts, a model-dependent part and a model-independent part. Using a previous work about online measurement of the power factor angle, the first part can be solved. For the second part, although the solution of the governing equation can be directly obtained, a lot of CPU time must be consumed due to the fact that it involves a lot of complex calculations. Therefore, a neural network was employed to simplify the calculations. Finally, experimental results and a corresponding analysis showed that the proposed algorithm can obtain the RMS values with a high precision while consuming less time when compared to directly solving the equations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.10
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• pp.1507-1512
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• 2010

In this study, the plasma induced by $CO_2$ laser lap welding of 6t Zn coated steel used for ship building was measured using photodiodes and a microphone. Then, the welding phenomenon with gap clearance of lap joint was compared with RMS-treated signal. Thus, we found that intensity of the RMS-treated signal increased with Zn vaporization; further, the presence of defects results in rapid variations with the RMS value as a function of lap-joint parameters. Besides, the FFT value of the raw signal with variations of changing welding parameters was calculated, and then the calculated FFT frequency value was set as the bandwidth of digital filter for a more accurate in-process monitoring. The RMS values were acquired by filtering the raw signal. By matching the weld beads and the calculated RMS values, we confirmed that there is a strong relationship between the signals and the defects.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.3
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• pp.251-257
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• 2019

This paper proposes a new measurement method using virtual power concept to measure the effective value of 3-phase voltage with variable frequency. The conventional effective value measurement method uses a method of integrating data sampled during one or half cycle of the power voltage and averaging it. In this method, since the effective voltage is calculated every cycle, a time delay occurs in the measured effective voltage and it is s a problem to measure the effective value of a device whose frequency varies from time to time, such as a generator. The proposed 3-phase voltage rms measurement method has an advantage that it can measure accurate voltage RMS value regardless of measurement frequency variation. In particular, there is an advantage in that it is possible to measure a 3-phase effective voltage rather than an average value of the effective voltage of each phase in a 3-phase unbalance voltage. In addition, the validity of the proposed method is verified by using the Psim simulation tool and the experimental results are analyzed by applying the proposed measurement algorithm to the actual three phase synchronous generator voltage measurement experiment.

• The Korean Journal of Nuclear Medicine Technology
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• v.27 no.2
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• pp.95-98
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• 2023

Purpose: The precision error of a bone density meter reflects the equipment and reproducibility of results by an examiner. Precision error values can be expressed as coefficient of variation (CV), CV%, and root mean square-SD (RMS-SD). The International Society for Clinical Densitometry (ISCD) currently recommends using RMS-SD as the precision error value. When a 95% confidence interval is applied, the least significant change (LSC) value is calculated by multiplying the precision error value by 2.77. Exceeding the LSC value reflects a significant difference in measured bone density. Therefore, the LSC value of a bone density equipment is an essential factor for accurately determining a patient's bone density. Accordingly, we aimed to calculate the LSC value of a bone density meter (Lunar iDXA, GE) and compare it with the value recommended by the ISCD. We also assessed whether the value measured by the iDXA equipment was below the LSC value recommended by ISCD. Material and Methods: The bone densities of the lumbar spine and thighs of 30 participants were measured twice, and the LSC values were calculated using the precision calculation tool provided by the ISCD (http://www.iscd.org). To check the reproducibility of the measurement, patients were asked to completely dismount from the equipment after the first measurement; the patient was then repositioned before proceeding with the second measurement. Results: The LSC values derived using the CV% values recommended by the ISCD were 5.3% for the lumbar spine and 5.0% for the thigh. The LSC values measured using our bone density equipment were 2.47% for the lumbar spine and 1.61% for the thigh. The LSC value using RMS-SD was 0.031 g/cm² for the lumbar spine and 0.017 g/cm² for the thigh. Conclusion: that the findings confirm that the CV% value measured using our bone density meter and the LSC value using RMS-SD were maintained very stably. This can be helpful for obtaining accurate measurements during bone density follow-up examinations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.3
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• pp.75-86
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• 2005

To investigate the fatigue characteristic of upper limbs, this study analyzed RMS(root mean square) and MPF(mean power frequency) value between initial and terminal stages of each experiment condition. And the effect of intermittent endurance time was evaluated using the Borg's CR10 value that was measured for the parts of upper limb. According to the results of ANOVA on RMS value, there were significant difference on the %MVC about push, pull, and down force exertion. Particularly the ANOVA of up force exertion was significant difference on shoulder flexion, elbow flexion and rest time as well as %MVC. The results of ANOVA for MPF value were significant difference on the %MVC in regard of the push and up force exertion. In case of up force exertion, MPF value tended to shift low frequency at all of the experiment conditions. According to the analysis of duty cycle, RMS value considerably increased over 50% duty cycle and as the %MVC increased, the duty cycle affected the increase of RMS value. MPF value for up and down force exertion decreased at 33%, 50% and 67% duty cycle for all of %MVC. Borg CR10 value of hand and forearm were below the 3-point to the 40% of endurance time at 30%MVC and to the 20% of endurance time at 50%MVC with the exception of up force exertion. But Borg CR10 values of upper arm and shoulder at up force exertion were more than 3-point to the 20% of endurance time at 30%MVC and in the start point of endurance time at 50%MVC.

• 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.