• KSTLE International Journal
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• 제1권1호
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• pp.29-33
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• 2000

In this study, a methodology is developed and confirmed to find the physical contact between the slider and disc due to the defects of disk during head seeking operation using acoustic emission (AE) signal. The head/disk contact was detected during random and standard seeks, whereas no contact was detected during track fellowing. During standard and random seeks, the torsion mode of slider excitation was observed at 680KHz. Therefore, it is thought that AE technique can be used as an alternative method of the glide test by monitoring existence of the torsional mode of the slider during seek operation or can be used to detect the spacing loss during seeking operation. By appropriately choosing the location of the sensor an order of magnitude increase in the sensitivity for RMS AE signal is observed. Therefore we can find take-off velocity clearly with high signal to noise ratio of AE signal.

• 제어로봇시스템학회논문지
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• 제16권7호
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• pp.720-725
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• 2010

In AGPS method, user position can be obtained even in the shadow region by improving signal sensitivity. A hybrid long integration scheme employing both coherent and non-coherent integration method is commonly used in AGPS receivers. Because coherent loss increases as residual frequency become large, residual frequency should be minimized to maximize coherent integration gain. This paper presents performance analysis of residual frequency estimator using FFT in fine-time assistance AGPS method. Considering the hardware complexity and the estimation accuracy, optimal length of FFT is proposed for GPS L1 C/A signal. Signal sensitivity for estimating the residual frequency is also analysed. By field experimental results, it is found that the residual frequency can be successfully estimated using 1 second snap-shot data when GPS signal strength is larger than -150 dBm and its RMS error is 3Hz.

• 한국생산제조학회지
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• 제20권3호
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• pp.304-309
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• 2011

A monitoring system for magnetic abrasive polishing process is necessary to ensure the polishing products the high quality and integrity. Acoustic emission (AE) signal is known to reflect the material removal phenomena in other machining processes. In a case of the magnetic abrasive polishing of non-magnetic materials, application of AE method is very difficult because of lower machining force on the surface of workpiece and the level of AE signal is extremely lower. In this study, AE sensor-based monitoring system is applied to the magnetic abrasive polishing. The relation between the level of the AE RMS and the surface roughness during the magnetic abrasive polishing of magnesium alloy steel is investigated.

• 한국정밀공학회지
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• 제11권4호
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• pp.69-76
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• 1994

AE(Acoustic Emission) signal is correlated to workpiece material, cutting conditions and tool geometry during metal cutting. The relationship between AE signal and cutting parameters can be obtained by theoretical model and experiments. The value of CR(Count Rate) is nearly constant in stable cutting, but when the chatter vibration occours, the value of CR is rapidly increased due to the vibration deformation zone. By experimental signal processing of AE, it is more effective than by RMS(Root Mean Square) measurement to detect the threshold of chatter vibration by CR measurement.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1291-1295
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• 2004

This paper proposed a new approach for endpoint detection of isolated speech, which proves to significantly improve the endpoint detection performance. The proposed algorithm relies on the root mean square energy (rms energy), zero crossing rate and spectral characteristics of the speech signal where the Euclidean distance measure is adopted using cepstral coefficients to accurately detect the endpoint of isolated speech. The algorithm offers better performance than traditional energy-based algorithm. The vocabulary for the experiment includes English digit from one to nine. These experimental results were conducted by 360 utterances from a male speaker. Experimental results show that the accuracy of the algorithm is quite acceptable. Moreover, the computation overload of this algorithm is low since the cepstral coefficients parameters will be used in feature extraction later of speech recognition procedure.

• 한국정보전자통신기술학회논문지
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• 제6권3호
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• pp.148-151
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• 2013

모델 오차 효과 및 민감도 분석을 사용하여 도래 방향 추정의 새로운 방법을 제시한다. 원하는 신호가 모델 오차 교정 효과를 통해 간섭을 제거한 후 얻어지게 되므로 추정에 있어서 채널 간섭 영향이 크게 줄어들게 된다. 모의실험을 통해 본 연구에서 제안된 방법이 기존의 방법에 비해 분해능과 정확성 추정이 향상되었음을 입증하였다.

• 전기학회논문지
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• 제59권8호
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• pp.1497-1505
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• 2010

The present study was performed to investigate the effect of aging on muscular activity of older subjects under the condition of fixed load muscle contraction. SEMG signals were recorded from old (46 women) and young (45 women) groups performing sustained isometric elbow flexion contraction with a fixed load during 30 seconds. Linear regression and mean square error (MSE) analysis with four characteristic variables (ARV, RMS, MDF, MNF) were used to compare the age-related difference (of local muscle fatigue and fluctuation of the amplitude and frequency) in the SEMG signal. The main results can be summarized as follows: During sustained muscle contraction with a fixed load: i) the MSE values of amplitude (ARV, RMS) and frequency (MDF, MNF) variables were more than 30% higher for the young than for the old adults; ii) the measures of local muscle fatigue (slope of the MDF and MNF) indicated greater fatigue in the old; and iii) the rate of increase of the SEMG amplitude was higher for the young than the old.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.693-696
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• 1999

This paper describes a new voltage recorder for the voltage management of a power distribution line by using a new voltage measurement technique. The RMS(Root Mean Square) voltage measurement for the power line under the assumption of a sinusoidal input voltage is taken by the full-wave rectifier, half-adder utilizing operational amplifier(OP) circuit. A/D converter utilizing a dual slope converter converts an analog voltage signal into a serial pulse. The pulse is counted with a single chip micro-controller, converted with the RMS voltage, and saved into a flash memory. In the last, a new voltage recorder with compact size and multifunction is developed. Also, Voltage Management System that can analyze the stored data via RS-232C cable is developed based on Windows 95 and Visual C++.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.1185-1188
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• 2003

This paper describes a design for a 2.5Gb/s serial data link CMOS transceiver based on the InfiniBand$^{TM}$ specification. The transceiver chip integrates data serializer, line driver, Tx PLL, deserializer, clock recovery, and lock detector. The designed transceiver is fabricated in a 0.25 ${\mu}{\textrm}{m}$ CMOS mixed-signal, 1-poly, 5-metal process. The first version chip occupies a 3.0mm x 3.3mm area and consumes 450mW with 2.5V supply. In 2.5 Gbps, the output jitter of transmitter measured at the point over a 1.2m, 50Ω coaxial cable is 8.811ps(rms), 68ps(p-p). In the receiver, VCO jitter is 18.5ps(rms), 130ps(p-p), the recovered data are found equivalent to the transmitted data as expected. In the design for second version chip, the proposed clock and data recovery circuit using linear phase detector can reduce jitter in the VCO of PLL.L.

• Journal of Advanced Marine Engineering and Technology
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• 제32권1호
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• pp.153-161
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• 2008

Recently, the research and development of the fish cage in open sea from domestic is active and it is almost complement with commercial scale test on 'seogwipo'. But domestic technology is not sufficient of management RMS(Remote Monitoring System) with advanced country, so it is difficult to maintenance and monitor fish cage in open sea. This paper introduces a fish cage environmental monitoring system for measuring pH, DO and temperature. A signal is treated with DAU(Data Acquisition Unit) by a wireless communication method and transfers data to host computer for data processing. These data are graphically shown on the monitor with LabVIEW program and logged on the data processing system in the form of file.