• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.4
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• pp.279-287
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• 1996

Frequency occupancy data can provide information on both the actual ratio of usage of individual frequency channels and the average ratio of usage of these frequency bands so that the reserved capacity of the spectrum can be estimated. Such an estimate can be used for the planning of additional spectrum allocations and as a means of assessing the impact of new technologies on spectrum usage. In this paper, we introduce about the frequency occu- pancy measurement system that is developed in Korea. And, we introduce Frequency Occupancy Ratio with a time period and with a area zone by using radio monitoing measurement datas.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.6
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• pp.249-254
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• 2006

A new algorithm for estimating power frequency is presented. Unlike conventional algorithms, the proposed algorithm is based on the fact that the magnitude gains of cosine and sine filters become different when the power frequency is deviated from the nominal value. This makes the algorithm capable of providing an accurate and fast estimate of the power frequency. To demonstrate the performance of the developed algorithm, various computer simulated data records are processed. The algorithm showed a high level of robustness as well as high measurement accuracy over a wide range of frequency changes. Moreover, the algorithm was highly immune to harmonics and noise.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.3
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• pp.27-30
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• 2016

PURPOSE : The effect of the vestibular caloric stimulation with ice water on the autonomic nervous system was investigated using pulse oximetry. METHOD : Thirty-four healthy men and women were subject to a 2-minute vestibular caloric stimulation with ice water, and autonomic nervous activities (low frequency, high frequency, and total power) were measured before and after the vestibular caloric stimulation. Data were analyzed separately for men and women. RESULT : Low frequency, high frequency, and total power in the men and low frequency in the women were statistically significantly higher after vestibular caloric stimulation. High frequency and total power in the women were higher but not significantly different after vestibular caloric stimulation. CONCLUSION : Vestibular caloric stimulation with ice water increases autonomic nervous activities, with the variation being within the normal range. The test can be considered safe for use.

• The Journal of Sustainable Design and Educational Environment Research
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• v.9 no.2
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• pp.1-8
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• 2010

This study is to present an engineering solution for the repair frequency and repair rates of a building. The existing data for the repair frequency and repair rates are used to draw the probability distribution for the generalized repair frequency and repair rate in a building. The suggested methodology can be widely used for most buildings to estimate the legal repair frequency and repair rates. Also, the methodology can be applied to resolve the risks on the maintenance costs in LC (Life Cycle) plans or LCC (Life Cycle Cost) analysis. As the future studies, there are the multiple regression analysis including the parameters on incurred costs and the decision methods on efficient repair and replacement.

• Phonetics and Speech Sciences
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• v.6 no.4
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• pp.133-139
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• 2014

This paper describes several approaches to transform a speaker's individuality to another's individuality using frequency warping between bilingual formant frequencies on different language environments. The proposed methods are simple and intuitive voice conversion algorithms that do not use training data between different languages. The approaches find the warping function from source speaker's frequency to target speaker's frequency on formant space. The formant space comprises four representative monophthongs for each language. The warping functions can be represented by piecewise linear equations, inverse matrix. The used features are pure frequency components including magnitudes, phases, and line spectral frequencies (LSF). The experiments show that the LSF-based voice conversion methods give better performance than other methods.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.304-308
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• 2003

A low cost solution employing harmonic oscillation to the frequency synthesizer at 5.8 GHz is proposed. The proposed frequency synthesizer is composed of 2.9GHz PLL chip, 2.9GHz oscillator, and 5.8GHz buffer amplifier. The measured data shows a frequency tuning range of 290MHz, ranging from 5.65 to 5.94GHz, about 0.5dBm of output power, and a phase noise of -107.67 dBc/Hz at the 100kHz offset frequency. All spurious signals including fundamental oscillation power (2.9GHz) are suppressed at least 15dBc than the desired second harmonic signal.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.70-79
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• 2013

In this paper, a comparative study on the frequency estimation methods using IRDWT (Improved Recursive Discrete Wavelet Transform), FRDWT(Fast Recursive Discrete Wavelet Transform), and GCDFT(Gain Compensator Discrete Fourier Transform) is presented. The 345[kV] power system modeling data of the Republic of Korea by EMTP-RV is used to evaluate the performance of the proposed two kinds of RDWT(IRDWT and FRDWT) and GCDFT. The simulation results show that the frequency estimation technique based on FRDWT could be the optimal frequency measurement method, and thus can be applied to FDR(Fault Disturbance Recorder) for wide-area blackout protection or frequency measurement apparatus.

• Journal of Communications and Networks
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• v.9 no.1
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• pp.75-83
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• 2007

Orthogonal frequency division multiplexing (OFDM) systems with multiple transmit antennas can exploit space-time block coding on each subchannel for reliable data transmission. Spacetime coded OFDM systems, however, are very sensitive to time variant channels because the channels need to be static over multiple OFDM symbol periods. In this paper, we propose to mitigate the channel variations in the frequency domain using a linear filter in the frequency domain that exploits the sparse structure of the system matrix in the frequency domain. Our approach has reduced complexity compared with alternative approaches based on time domain block-linear filters. Simulation results demonstrate that our proposed frequency domain block-linear filter reduces computational complexity by more than a factor of ten at the cost of small performance degradation, compared with a time domain block-linear filter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.1061-1067
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• 2005

The resonant frequency modulation of $YBa_2Cu_3O_{7-x}$ meander lines has been investigated as functions of optical pulse energy and temperature by using a network analyzer. The frequency-domain measurements are performed by controlling both the resonant frequency and the frequency width. The meander lines, configured in a microstrip geometry, are illuminated by optical pulses from an actively mode-locked Nd:YAG laser. The variation of the resonant frequency shows a quadratic dependence on the reduced optical pulse energy $P/P_c$, where $P_c$ is defined as the critical optical pulse energy at which resonance signal has disappeared. As for the dependence on temperature, the results are in good agreement with the previously reported data.

• Ocean and Polar Research
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• v.29 no.4
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• pp.311-316
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• 2007

Ocean noise may be used for monitoring wind speed and rainfall rate on the sea surface, as well as for tracking whales' migration routes. In particular, low-frequency ocean noise has recently been of concern with relation to the behavior of marine mammals. Low-frequency ocean noise has been increasing over the past few decades due to increase of ship traffic and offshore oil industry activities. Mechanical noise such as flow noise and cable strumming noise may be induced if low-frequency ocean noise is measured by cabled traditional hydrophone in high current areas. To successfully measure low-frequency ocean noise in a shallow water environment with strong current, we developed a self-recording hydrophone. This paper describes the main configurations of the self-recording hydrophone and presents some results on measured data.