• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.494-502
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• 2015

This paper introduces methods to measure vibration using a fringe pattern. These methods use variations of a fringe pattern in reflective monochromatic interferometry, without additional components. With the proposed methods we measured the vibrations of four waveform with amplitude 100 nm. When the vibrational amplitude is greater than a quarter wavelength of the light employed, however, the measured results are distorted due to ambiguity. Thus we propose advanced methods to solve this problem, and also measure the vibrations of two waveformswith an amplitude of $1{\mu}m$. To verify the performance of the proposed methods, we compare the results to those from an accelerometer. Multifrequency vibrations of 1, 5, 10, and 20 Hz are measured by both techniques, and the results compared in the frequency domain.

• ETRI Journal
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• v.9 no.3
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• pp.74-85
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• 1987

In this paper, a new kind of dual tone multifrequency receiver(DTMFR) is proposed, in which detection is made in terms of the partial correlation(PARCOR) coefficients for efficient DTMF signal detection against both temporary decoding errors by crosstalks possibly coming from adjoint telephone lines during transmission and so-called digit simulation by background voice or noise signals during interdigit period. A simulation study on the behaviour of PARCOR coefficients for tone signals and non-signals has been performed in order to provide the rationale on the feasibility of the proposed DTMFR algorithm. Based upon simulation results, a more refined detection strategy as an example is presented and explained together with the corresponding decision logic.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.105-108
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• 2000

The economical detection of dual-tone multifrequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each channel has independently a DTMF receiver, and I t informs the detected signal to processors. This paper analyze the power spectra and evaluate the performance of DTMF receiver by using tile quick Fourier transform(QFT) algorithm. As experimental results, it show the improved performance to the DTMF receivers and reduce memory waste and process the real-time.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.50.1-50.1
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• 2011

We report the results of the monitoring of a flaring gamma-ray blazar, 3C454.3 in total flux density at 22 and 43GHz and in polarization at 22GHz with KVN Ulsan 21-m radio telescope every 3-4 days from 19 November 2010 to 31 January 2011. After an extraordinary 5-day gamma-ray outburst in November 2010, the radio total flux density at 22/43GHz and the linear polarization at 22GHz has been decreased with a variation of a short time scale. In this paper, we also discuss a spectral change of 3C454.3 at 22 and 43GHz after the extraordinary gamma-ray outburst.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.185-188
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• 1996

Noninvasive multifrequency microwave radiometry using coaxial waveguide antenna has been investigated for a homogeneous and four layer human body model. The coupling between coaxial waveguide antenna and a. biological object is analyzed by use of the FDTD method to obtain the absorbed power patterns in the media. The object studied in this paper is a homogeneous and four-layered lossy medium. The specific absorption rates(SAR) distribution is calculated in each region by use of the steady-state response in FDTD method.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.2
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• pp.155-161
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• 2010

Recently, the electromagnetic techniques of the eddy current testing(ECT), alternating current field testing, magnetic flux leakage testing and remote field testing have been used as a nondestructive evaluation method based on the electromagnetic induction. The eddy current testing is now widely accepted as a NDE method for the heat exchanger tube in the electric power industry, chemical, shipbuilding, and military. The ECT system mainly consists of the synthesizer module, analog module, analog-to-digital converter, power supplier, and data acquisition and analysis program. In this study, the synthesizer module and the analog module which are essential to the ECT system were primarily developed. The developed ECT system is basically a multifrequency type which is able to inject the maximum four frequencies based on the frequency and time domain multiplexing method. Conclusively, we confirmed that the EC signal was processed appropriately in each circuit modules, and the Lissajous EC signal was displayed in the impedance plane.

• Journal of The Korean Astronomical Society
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• v.36 no.spc1
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• pp.29-36
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• 2003

Quiescent solar radiation, at microwave spectral regime, is dominated by gyroresonant and thermal Bremsstrahlung radiations from hot electrons residing in solar active region corona. These radiations are known to provide excellent diagnostics on the coronal temperature, density, and magnetic field, provided that spatially resolved spectra are available from observations. In this paper we present an imaging spectroscopy implemented for a bipolar active region, AR 7912, using the multifrequency interferometric data from the Owens Valley Solar Array (OVSA), as processed with a new imaging technique, so-called Spatio-Spectral Maximum Entropy Method (SSMEM). From the microwave maps at 26 frequencies in the range of 1.2-12.4 GHz at both right- and left-circular polarizations, we construct spatially resolved brightness spectra in every reconstructed pixel of about 2 arcsec interval. These spectra allowed us to determine 2-D distribution of electron temperature, magnetic field of coronal base, and emission measure at the coronal base above the active region. We briefly compare the present result with existing studies of the coronal active regions.

• Journal of Korean Physical Therapy Science
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• v.10 no.2
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• pp.137-144
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• 2003

The purpose of this study was to investigate the difference of body composition of the elderly according to the age. This study consisted of elder male(n=48) and elder female(n=58). The average age of male elder and female elder was 73.81, 73.05 years. The data were analyzed with t-test, using SPSSWIN 10.1 program. Body composition was measured using Inbody 3.0(seoul, korea) of segmental multifrequency impedance analyzer technique. The result of this study were the following : 1. The difference of body composition according to the age 1) The MV(Muscle Volume)of male elder was significant difference among group(p<.05). The MV of female elder was very significant difference among group(p<.01). 2) The %FAT of male elder and female elder was no significant difference among group. 3) The FFM(Free Fat Mass)of male elder was significant difference among group(p<.05). The FFM of female elder was very significant difference among group(p<.01). 4) The TBW(Total Body Water)of male elder was significant difference among group(p<.05) The TBW of female elder was very significant difference among group(p<.01). 5) The WHR(Waist to Hip Ratio)of male elder was significant difference among group(p<.05). The WHR of female elder was very significant difference among group(p<.01).

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.60.1-60.1
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• 2014

In the center of an Active Galactic Nuclei(AGN) is a supermassive black hole which accretes matter from its surroundings. The radio-loud AGN launch two relativistic jets perpendicular to the accretion disk which terminates into radio lobes located up to megaparsec away. Blazars form a small subset of radio-loud AGNs with one of two relativistic jets pointing toward the observer's line of sight. Many blazars often show flares at different frequencies. And these flares at different frequencies are known that they often correlate with each other. In 2013 December, there was a gamma-ray flare in 3C 279, one of the brightest blazars, Dec 2013. So we want to reveal that whether this flare correlates with radio flare or not, and where the flare originate. With polarization observation at radio frequencies, we can study the physical properties of the magnetic field in the innermost regions of the relativistic jets. Therefore, we have conducted polarization monitoring of this source from Dec. 2013 to Jun. 2014 with KVN(Korea VLBI Network) radio telescopes at 22, 43 and 86GHz. Here we present the initial results of the monitoring of 3C 279. We prospect that we can reveal the origin of this gamma-ray flare by comparing with our radio data.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.3
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• pp.29-32
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• 1983

This paper is an experimental study on the generation principles of digital frequency using ROM-table look-up method and the design of the MF digital Sender used in signalling systems between ESS. After construction of MF digital Sender, through experiment, we concluded that this system well suit for CCITT (International Telegraph and Telephone Consultative Committee) recommendation and this basic principle can be applied to the signalling method using frequency Within voice-band. Also it can be applied to R2 MFC signalling equipment which is used between electronic switching systems (ESS) signalling system.