• Journal of the Korean Society for Nondestructive Testing
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• v.11 no.1
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• pp.31-37
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• 1991

Acoustic emission(AE) signals detected during metal cutting were applied as the experimental test to sensing tool wear and chipping on the NC vertical milling machine. The in-process detection of cutting tool wear including chipping, cracking and fracture has been investigated by means of AE in spite of vibration or noise through intermittent metal cutting, then the following results were obtained 1) When the tool wear is increased suddenly, or the amplitude of AE signals changes largely, it indicates chipping or breaking of the insert tip. 2) It was confirmed that AE signal is highly sensitive to the cutting speed and tool wear. 3) At the early period of cutting, the wear were large and RMS value increased highly by the influence of minute chipping and cracking, etc. Therefore, the above situations should be considered for the time when the tool would be changed.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.1
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• pp.73-80
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• 2006

In order to compute the radiated sound from a vibrating structure, the Rayleigh's integral equation has to be derived from the Helmholtz equation using Green's function. Generally, the surface velocity in the Rayleigh's integral equation uses the root mean square(rms) velocity. The calculation value is too large, because it's not considered cancelation. On the other hand. using the complex velocity, the sound pressure is calculated too small, because it considers that sound is perfectly canceled out. Therefore, this thesis proposes a correction factor(CF) which considers vibration modes and the method by which to calculate the radiating sound pressure. The theoretical results are compared with the experimental values, and the proposed method can be verified with confluence.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.75-83
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• 2004

With the rotating machinery getting more accurate and diversified, the necessity fur an appropriate diagnosis technique and maintenance system has been greatly recognized. However, until now, the operator has executed a monitoring of the machine by the senses or simple the change of RMS (root mean Square) value. So, the diagnostic expert system using the fuzzy inference which the operator can judge easily and expertly a condition of the machine is developed through this study. In this paper, the hardware and software of the diagnostic expert system was composed and the identification of the diagnostic performance of the developed system for 5 fault phenomena was carried out.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.686_687
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• 2009

The traceability maintenance system for the AC voltage and current has been developed at the frequency range of 20 Hz to 100 Hz without using any compensation technique which is used at thermal converter (TC) ac-dc transfer system at low frequencies. The system uses a digital voltmeter (DVM) as a data acquisition system of the input waveform and stored data in memory. The developed algorithm acquires and processes the sampling data to calculate the root mean square (rms) value of the input voltage of DVM which operates at DC 10 V range for better accuracy. The best uncertainty of the AC voltage measurements is $3 {\mu}V/V$ within the frequency range. The best uncertainty of the AC current measurements is better than the $5 {\mu}A/A$ and mainly depend on the current to voltage converter, ac-dc current shunt or Current Transformer (CT), used for the measurement

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.1
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• pp.52-59
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• 1999

An experimental study on the grinding temperature, surface roughness and Acoustic Emission(AE) signals was conducted with different shapes of wheel. The grinding characteristics for slotted shapes of wheel changed by width and helical angle, were compared with those by general one. Lower grinding temperature was obtained for 30$^{\circ}$helical angle with 10mm width and Root Mean square(RMS) values of AE signals were lower for slotted shapes rather than general one. Surface roughness characteristics of slotted shapes found to be rough but the value of roughness for 45$^{\circ}$helical angel with 6mm width, represented to similar tendency general one.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.290-300
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• 1995

본 연구는 JPEG(Joint Photographic Experts Group)표준 영상압축 방법을 이용한 원격측정 (remote measuring) 시스템을 다룬다. 많은 디지탈 비디오(digital video)이 응용중에서 주요 어려움은 디지탈 영상(digital image)을 직접적으로 표현하기 위해 필요한 방대한 데이터의 처리문제이다. 그리고 디지탈 영상의 직접적인 사용은 고수준 기억용량(high storage)과 전송비용(transmission costs)으로 인하여 응용상 여러가지 제약조건이 수반되었다. 이런 이유로 인하여 여러가지 영상압축 기법이 개발되어왔으며 본 연구는 정지영상(still pictures)에 대하여 JPEG 표준을 사용한 영상압축과 압축된 영상을 사용하여 실제 제조업의 공정검사에 응용하는 것이다. 수행도 평가척도로서 원래영상과 압축된 영상과의 압축비, 원래영상과 압축된 영상과의 픽셀(pixel)의 회색도 값(gray-level value)의 평균과 RMSE(root mean square error), 그리고 원래영상과 압축된 영상을 원거리(또는 근거리)로 전송하여 전송된 압축영상을 푼 후 두 지점간의 거리 측정에 따르는 실제거리와 측정거리에 대한 오차를 이용하였다.

• Journal of Biomedical Engineering Research
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• v.12 no.4
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• pp.309-314
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• 1991

This paper describes the results of study on the measurement method of TRMS (true root mean square value) In electrosurgical unit. We used three type (direct computing type, indirect computing type, thermal converting type) in the measurement of TRMS. Three types of measurement method were compared with respect to power level, frequencey and crest factor in addition to environmental temperature. In three of them, the thermal converting type was the best for th electrosurgical unit analyzer

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.832-836
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• 1997

An experimental study on the grinding temperature, surface roughness and Acoustic Emission(AE) signal was conducted with different shapes of wheel. The grinding characteristics by slotted shapes of wheel changed by width and helical angle,were compared with those by general one. Lower grinding temperature was obtained for 30 .deg. helical angel with 10mm width and Root Mean Square(RMS) values of AE signals were lower for slotted shapes rather than general one. Surface roughness characteristic of slotted shapes found to be rough,but the value of roughness for 45 .deg. helical angel with 6mm width, represented to similar tendency general one.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.852-853
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• 2008

This paper proposes an optimal design method for the shape optimization of the permanent magnets (PM) of an in-wheel permanent magnet synchronous motor (PMSM) to reduce the cogging torque considering a total harmonic distortion (THD) and a root mean square (RMS) value of back-EMF. In this method, the Kriging model based on a design of experiment (DOE) is applied to interpolate the objective function in the spaces of design parameters. The optimal design method for the PM of an in-wheel PMSM has to consider multi-variable and multi-objective functions. The developed design method is applied to the optimization for the PM of an in-wheel PMSM.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1783-1793
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• 1993

Pattern recognition technique using fuzzy c-means algorithm and multilayer perceptron was applied to classify tool wear states in turning. The tool wear states were categorized into the three regions 'Initial', 'Normal', 'Severe' wear. The root mean square(RMS) value of acoustic emission(AE) and current signal was used for the classification of tool wear states. The simulation results showed that a fuzzy c-means algorithm was better than the conventional pattern recognition techniques for classifying ambiguous informations. And normalized RMS signal can provide good results for classifying tool wear. In addition, a fuzzy c-means algorithm(success rate for tool wear classification : 87%) is more efficient than the multilayer perceptron(success rate for tool wear classification : 70%).