• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1433-1440
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• 2015

In this paper, we propose an unambiguous correlation function to improve tracking performance for binary offset carrier (BOC) signals. Specifically, we divide a BOC sub-carrier into multiple rectangular pulses, and analyze that the BOC autocorrelation function is made up of the sum of several partial correlation functions. Then, we obtain two sub-correlation functions by combining two partial correlation functions and propose a novel unambiguous correlation function with no side-peak which can be regulated its width based on the combination of the sub-correlation functions and partial correlation functions. From numerical results, it is confirmed that the proposed correlation function provides a tracking performance improvement over the conventional correlation functions in terms of the tracking error standard deviation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.22-34
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• 1997

In LEO system, the signal degradation is mainly due to fading and Doppler shift, so that the analysis of the signal degradation and compensation techniques are very important. As the Doppler shift compensator, the block demodulator has been known to be useful in compensating for the time-varing Doppler shift, but its compensating ability is about several hundreds Hz in 32 ksymbols / s QAM (QPSK) signal transmission. Therefore, in this paper, to compensate for severe fading and Doppler shift more than several kHz, we use a conventional pilot symbol-aided fading compensator, and propose the Doppler shift compensator. It is shown that the proposed compensator is able to compensate for Doppler shift more than several kHz. And a pilot symbol-aided fading compensator is shown to be a suitable scheme for severe Rician fading ($K{\leq}10 dB$) as well as Rayleigh fading. Also, it is shown that the equal gain combiner improves greatly the QAM performance even if the fading or Doppler shift becomes deeper or larger.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.125-134
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• 2012

This study examines how the concentration of Fine Particles(PM10: Fine Particles of under Diameter $10{\mu}m$) included in the air influences on the satellite signal transmission frequency band. For the study of satellite signal attenuation rate by the concentration of Fine Particles, the concentration of Fine Particles classified 7 levels, below $50{\mu}g/m^3$, below $100{\mu}g/m^3$, below $200{\mu}g/m^3$, below $400{\mu}g/m^3$, below $800{\mu}g/m^3$, below $1,600{\mu}g/m^3$, below $3,200{\mu}g/m^3$. After then, it analyzed how much each concentration influenced on the satellite signal transmission frequency band.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.521-537
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• 2000

Ultrasonic imaging is the most widely used modality among modern imaging device for medical diagnosis and the system performance has been improved dramatically since early 90's due to the rapid advances in DSP performance and VLSI technology that made it possible to employ more sophisticated algorithms. This paper describes "main stream" digital signal processing functions along with the associated implementation considerations in modern medical ultrasound imaging systems. Topics covered include signal processing methods for resolution improvement, ultrasound imaging system architectures, roles and necessity of the applications of DSP and VLSI technology in the development of the medical ultrasound imaging systems, and array signal processing techniques for ultrasound focusing.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.2
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• pp.137-144
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• 2009

In this paper, the signal analysis of eddy current array probe was performed to analyze the electromagnetic characteristics with the variation of FBH(flat bottomed hole) defects size on steam generator tube in NPP(nuclear power plants) using the electromagnetic finite element method. To obtain the electromagnetic characteristic of probes, the governing equation was derived from Maxwell's equations, and the individual problem was analyzed by using the 3-dimensional finite element method. For the simulation FBH defects were used. The depth of FBH defects were 20%, 40%, 60%, 80% and 100% of steam generator(SG) tube thickness, and it was assumed that the defects were located on the tube outside. And the operation frequencies of 100 kHz, 300 kHz and 400 kHz were used. Material of specimen was Inconel 600 which is usually used for SG tubes in NPP. The signal difference could be observed according to the size variation of depth of FBH defects and operation frequencies. The results in this paper can be helpful when the ECT(eddy current testing) signals from EC array probe are evaluated and analyzed.

• The Journal of the Acoustical Society of Korea
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• v.19 no.8
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• pp.12-21
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• 2000

In this paper, we propose a novel hearing aid algorithm for sensorinural hearing loss restoration with multi-channel(band) dynamic range compression and psychoacoustics. In this way, we can present a normal perception condition to the impaired listener. The proposed algorithm make loudness scaling function achieve proper loudness level, and analysis masking property for the signal will be perceived to impaired listener, and then, restore normal spectral contrast using SMR(signal-to-masking ratio) defined by distance between the level of each frequency and masking threshold.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.467-472
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• 2008

In this paper, we analyzed the error rate Performance of convolution coded 16 QAM signal with Optimum Threshold Detection with selective combining diversity in Rician Fading Environments. The performance of 16-QAM signal with CTD (conventional threshold detection) which employs convolution coding technique was analyzed and the performance improvement of convolution coded 16-QAM signal with OTD (optimum threshold detection) which is varied according to fading parameter "K" and AWGN in Rician Fading channel was simulated. As a result of analysis, it was shown the effect of performance improvement to overcome the environment of mobile radio data communication channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7A
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• pp.807-813
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• 2004

This paper corresponded to Smart-UAV(Smart Unmanned Aerial Vehicle) technology development, a part of “The 21th Century New-Frontier Development Project” being propelled in accordance with enlarging the necessity of concentration development by selecting our strong technique being able to compete in the international society of knowledge based economy in the 21th century. Also, we designed Ku-band airborne video transceiver system performing to receive the TC(Tele-Command) signal needed to be applicable of Smart-UAV, and send the video and TM(Tele-Metry) signal at the same time. Moreover, we analyzed it in order to satisfy the system request of designed whole communication system, and established the validity on this paper going through by module simulation and manufacture of the whole system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6C
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• pp.423-428
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• 2008

We consider the use of cooperative diversity in a multiuser wireless data network. This paper provides an analysis of the interaction between cooperative diversity and multiuser diversity on downlink channels. By using approximation of the signal-to-noise ratio (SNR) distribution of each cooperative diversity link by Gamma distribution, an analytic expression is derived for the average throughput of a single-cell wireless system with multiple cooperative diversity links combined with a fair-access scheduler. The proposed analytic approach is verified through comparisons with simulated results and shows that cooperative diversity makes the detrimental impacts on multiuser diversity.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.1-6
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• 1999

The only transmission characteristics in frequency domain is considered when using the tapered transmission line for wide-band impedance matching in MCM and MIC designs. In this paper, the distortion of an electrical pulse with rise/fall time resulting from dispersion and reflection as it propagates along a tapered microstrip line is investigated, and the delay time and distortion rate with respect to input and load impedances are analyzed on triangular and exponential tapered lines. A dispersion model of the phase constant proposed by Kirschning-Jansen is used to meet the frequency, accuracy and microstrip parametric requirements. The triangular tapered line shows both shorter delay time and higher distortion rate than those of the exponential tapered line. Furthermore, the amplitude of signal reflected from load point is calculated in time domain.