• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.224-228
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• 2003

In this paper, for phase lock loop(PLL) synthesizer, we introduce a novel but simple and low cost frequency modulation(FM) circuit of a flat peak frequency deviation for modulation signal from high to very low frequency penetrating into the loop-bandwidth of PLL. The FM circuit was basically designed to compensate an amount of feedback of the loop filter in PLL. The circuit also includes the capability of the adjustment of peak frequency deviation and blocking the interference with the loop filter. The designed circuit was successfully implemented and showed the flat frequency deviation as expected in the design.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.6
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• pp.599-607
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• 2004

In this paper, using phase locked loop(PLL) synthesizer, we introduce a novel but simple and low cost frequency modulation(FM) circuit of a flat peak frequency deviation fur modulation signal whose frequency covers from outside to inside of the loop-bandwidth of PLL. The FM circuit was basically designed to compensate an amount of feedback of the loop filter in PLL. The circuit also includes the capability of the adjustment of peak frequency deviation and of blocking the intereference with the loop filter. The designed circuit was successfully implemented and showed the flat frequency deviation as expected in the design. In addition, the novel measurement method of the wideband FM modulation index is suggested verified With the suggest measurement, it can be successfully shown the designed circuit has the expected frequency deviation.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.129-134
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• 2007

The purpose of this study was to determine the variability of components of the vertical ground reaction force signal to seek the suitable number of attempt datum to be analyzed during running at 2m/s and 4m/s. For this study, six subjects (height mean:$174.5{\pm}4.4cm$, weight $671.5{\pm}116.4N.$, age:$25.0{\pm}yrs.$) were selected and asked to run at least 3 times each run condition randomly. FFT(fast Fourier transform) was used to analyze the frequency domain analysis of the vertical ground reaction forces signal and an accumulated PSD (power spectrum density) was calculated to reconstruct the certain signal. To examine the deviation of the vertical ground reaction between signals collected from an different number of attempt, variability of frequency, magnitude of passive peak, time up to the passive peak and maximum load rate were determined in a coefficient of variance. The variability analysis revealed that when analyze the vertical reaction force components at 2m/s speed running, which belongs to slow pace relatively, it would be good to calculate these components from signal of one attempt, but 4m/s speed running needs data collected from two attempts to decrease the deviation of signal between attempts. In summary, when analyzing the frequency and passive peak of the vertical reaction force signal during the fast run, it should be considered the number of attempt.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.744-747
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• 1991

In this paper, the design of optimal feedforward regulators with the optimal feedforward filters for improving power frequency deviations in an interconnected system, using a polynominal LQG approach, is proposed. The performances of the regulators with the optimal feedforward filters were compared with the frequency feedback regulator only in power system by simulation. The results show that the optimal feedforward regulators reduce the power frequency standard deviation by 25%-60% in the white noise load and the peak deviation in the step load by 8%-27%.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.337-348
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• 2017

The tension of warp from trawler and sea-floor contact can generate tilt and wake turbulence around otter boards. Preliminary measurements of otter board tilt and 3-D flow velocity during bottom trawl operations were taken using a vector instrument to investigate the effects of wake turbulence at the trailing edge of the otter board. Tilt data (i.e., yaw, pitch, and roll) at 1 Hz and flow data (velocities in the towing, lateral, and vertical directions) at 16 Hz were analyzed to determine their periods and amplitudes using global wavelet and peak event analyses. The mean period (${\pm}standard$ deviation) of the tilt from the peak event analysis ($5{\pm}2s$) was longer or double than that of flow velocity ($3{\pm}2s$). The two periods also had a significant linear relationship. The turbulence rate of flow was 30-50% at the trailing edge and was closely related to roll deviation. The frequency of phase difference ratios (i.e., peak time differences between tilts and flow periods) was significantly different from random occurrence in two trials, possibly due to side tidal effects. However, in the other trials, flow peaks were random, as shown by the even peak times between tilts and flows. Future studies should focus on reducing tilt variation, wake turbulence, and bottom contact to stabilize otter board motion.

• Journal of Welding and Joining
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• v.16 no.6
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• pp.52-58
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• 1998

The effect of Si content in welding wires on th arc stability was investigate, in the region of short circuit transfer and spray transfer. In the region of short circuit transfer, with increasing Si content, average arcing time and average short circuit time were increased. Therefore, droplet transfer frequency was decreased, due to the increase of arcing time and peak current at the moment of arc-reiginition was increased, due to the increase of short circuit time. In the region of spray transfer, the fluctuations of arc current and arc voltage was the most stable in wire with Si content of about 00.60 wt.%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.129-133
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• 2019

Frequency resource efficiency is important in satellite communication systems. One of the causes of a waste of frequency resource is bad flatness. In the case, flatness of satellite Tx terminals would be worse by ACI and guard band. In order to overcome this problem, this paper proposes a technique for frequency response equalization in satellite Tx terminals. First of all, a general linear polynomial expression which meets least squares of representative measurement data is calculated to interpolate unmeasured data. And then flatness can be adjusted using the polynomial expression. Simulation results illustrate adjusted data have lower peak to peak and standard deviation than original data, and these show that flatness be improved.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.10
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• pp.1095-1101
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• 2013

The purpose of this study was to verify the effect on improvement of muscle strength unbalance according to load deviation protocol during whole body vibration exercise. Seventeen female volunteers (age $22{\pm}3$ years, height $160{\pm}4.9$ cm, weight $49{\pm}.8$ kg) participated in this experiment. The subjects performed squat exercise in WBV platform. Exercise were performed five set a day including 15 time a set, three days a week, and during 4 weeks. Vibration stimulus was 25Hz as frequency and intensity was dominant leg 1mm and non-dominant leg 4mm. The results in WBV group showed that the differences of peak torque in 16% were getting decreasing significantly after 4 weeks from 16.2% to 5.2%. This result means that WBV with load deviation protocol could provide muscle strength exercise for muscle strength balance. Our study found out that WBV of load deviation protocol could provide muscle strength exercise for improving muscle imbalance.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.199-204
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• 1996

In the present the mean temperature and the temperature fluctuation of non-isothermal parallel liquid sodium jets were measured and analyzed changing the temperature difference and mean velocity of the hot and cold sodium. The sampling frequency and sampling time were 420Hz and three seconds, respectively. The wave-form characteristics were discussed in regard to the peak-to-peak amplitudes and the periods provided by a wave analysis. And also the correlations of the temperature fluctuation in rms value and the peak amplitude are derived. The overall mean accuracy ratios of the correlations are 1.07 and 1.08 with a standard deviation of 0.17 and 0.15, respectively.

• Journal of KIISE
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• v.45 no.3
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• pp.311-320
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• 2018

Recently, the use of digital audio and video as proof in criminal and all kinds of litigation is increasing, and scientific investigation using digital forensic technique is developing. With the development of computing and file editing technologies, anyone can simply manipulate video files, and the number of cases of manipulating digital data is increasing. As a result, the integrity of the evidence and the reliability of the evidence Is required. In this paper, we propose a technique for extracting the Electrical Network Frequency (ENF) through a grid of power grids according to the geographical environment for power supply, and then performing signal processing for peak detection using QIFFT. Through the detection algorithm using the standard deviation, it was confirmed that the video file was falsified with 73% accuracy and the forgery point was found.