• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.5
• /
• pp.506-514
• /
• 2008

At coverage boundaries of cellular systems including the recent WiBro standard which operate with full frequency reuse for increased spectral efficiency, interference signals from the base stations(BS) of adjacent cells degrade the receiver performance. In this paper, a detection method for multiple-antenna mobile stations(MS) is proposed for downlink performance improvement at coverage boundaries of cellular systems. For the performance verification, we obtain the probability density function(pdf) of the effective signal-to-interference and noise ratio(SINR) according to the variation of the interference signals from adjacent cells as well as the number of MS antennas, and calculate the transmission efficiency. We also verify the performance of proposed method with simulation results, to demonstrate a significant performance improvement is achieved over the maximal ratio combining(MRC) and spatial demultiplexing(SD) methods in terms of the effective SINR and the spectral efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.7
• /
• pp.1807-1816
• /
• 1998

The interference probability between non-geostationary-statellite orbit mobile station is calculated when the two systems are sharing the frquency band below 1 GHz. The probability density function of a mobile earth station(MES) is calculated based on the established propagation model and then, a probability of exceeding the threshold level is derived. By changing the average transimission per unit time of total MSS(Moblie satellite service) area and the ratio of transmitters for specific area, we obtain the average transmission per unit time for the area under consideration. From this, the exceedance probability for the given pfd threshold level is evaluated. The exceedance probability is increased as the average transmissio per unit time and ratio become larger. Also the effect of filter isolation between channels is accounted for.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2005.10a
• /
• pp.11-16
• /
• 2005

When a vessel passes near a channel boundary, the boundary creates forces and moments acting on the vessel. With the same reason passing of two vessels closely gives same effects to each other. The principal. difference between the above two cases is that the channel boundary is long and constant shape compared to those of vessels. The interaction forces and moments between two vessels could be assumed to be functions of the longitudinal distance $x_0$, transverse distance $y_0$ and speeds of the two vessels. Passage of one vessel close to another is important operationally from the viewpoint of replenishment at sea, avoidance of collisions and passage of two vessels in restricted channels. The authors studied the interactions between two vessels running closely and calculated safe conducting distances according to separated distances and speeds of the two vessels.

• Geophysics and Geophysical Exploration
• /
• v.27 no.2
• /
• pp.144-153
• /
• 2024

Recent research is increasingly focused on utilizing seismic waves for structure health monitoring (SHM). Specifically, seismic interferometry, a technique applied in geophysical surveys using ambient noise, is widely applied in SHM. This method involves analyzing the response of buildings to propagating seismic waves. This enables the estimation of changes in structural stiffness and the evaluation of the location and presence of damage. Analysis of seismic interferometry applied to SHM, along with case studies, indicates its highly effective application for assessing structural stability and monitoring building conditions. Seismic interferometry is thus recognized as an efficient approach for evaluating building integrity and damage detection in SHM and monitoring applications.

• Journal of Broadcast Engineering
• /
• v.17 no.1
• /
• pp.195-198
• /
• 2012

The N basis functions are typically chosen so that Surface reflectance functions(SRFs) and spectral power distributions (SPDs) can be accurately reconstructed from their N-dimensional vector codes. Typical rendering applications assume that the resulting mapping is an isomorphism where vector operations of addition, scalar multiplication, component-wise multiplication on the N-vectors can be used to model physical operations such as superposition of lights, light-surface interactions and inter-reflection. The vector operations do not mirror the physical. However, if the choice of basis functions is restricted to characteristic functions then the resulting map between SPDs/SRFs and N-vectors is anisomorphism that preserves the physical operations needed in rendering. This paper will show how to select optimal characteristic function bases of any dimension N (number of basis functions) and also evaluate how accurately a large set of Munsell color chips can approximated as basis functions of dimension N.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.3
• /
• pp.291-298
• /
• 2019

In this paper, we propose a Fresnel transform method using various wavelet functions to efficiently decompose digital holograms. After implementing the proposed wavelet function-based Fresnelet transforms, we apply it to the digital hologram and analyze the energy characteristics of the coefficients. The implemented wavelet transform-based Fresnelet transform is well suited for reconstructing and processing holograms which are optically obtained or generated by computer-generated hologram technique. After analyzing the characteristics of the spline function, we discuss wavelet multiresolution analysis method based on it. Through this process, we proposed a transform tool that can effectively decompose fringe patterns generated by optical interference phenomena. We implement Fresnelet transform based on wavelet function with various decomposition properties and show the results of decomposing fringe pattern using it. The results show that the energy distribution of the coefficients is significantly different depending on whether the random phase is included or not.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.4
• /
• pp.427-438
• /
• 1998

The bit error rate(BER) performance of Trellis Coded QPSK signal in the presence of cochannel interference (CCI) and Rician fading is investigated. The trellis coded QPSK system adopts Maximum Ratio Combining (MRC) diversity reception and Reed-Solomon code to enhance system performance. Using the derived error probability equation, the error performance of trellis coded QPSK system has been evaluated and shown in figures to discuss as a function of signal power to noise power ratio (SNR), signal power to interference power ratio(SIR), direct to indirect signal power ratio ($K_R$), the number of diversity branch (M), the frame length of Reed-Solomon code (n), the number of error correction symbol (t), and the number of state of trellis encoder. From the results, we know that proposed system is affected by cochannel interference and fading in microcell environment. Also, BER performance of Trellis Coded QPSK system can be improved as increasing either the power of desired signal or the value of SIR. And the BER floor in microcellular system is caused by the cochannel interference and it occurs at high BER when SIR is low. And Reed-Solomon code (n=15, t=2) is more effective to restrain the affection of CCI and fading than MRC diversity reception (M=2).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.1
• /
• pp.343-347
• /
• 2012

Non-linear equalization techniques using decision feedback structure are highly demanded for cancellation of intersymbol interferences occurred in severe channel environments. In this paper decision feedback structure is applied to the linear blind equalizer algorithm that is based on information theoretic learning and a randomly generated symbol set. At the decision feedback equalizer (DFE) the random symbols are generated to have the same probability density function (PDF) as that of the transmitted symbols. By minimizing difference between the PDF of blind DFE output and that of randomly generated symbols, the proposed DFE algorithm produces equalized output signal. From the simulation results, the proposed method has shown enhanced convergence and error performance compared to its linear counterpart.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.5
• /
• pp.16-22
• /
• 2000

This paper presents a compression algorithm applicable for transmitting a HPO hologram data. The proposed algorithm exploits a modulating function to compress the bandwidth of the hologram pattern, resulting in decimation due to relaxed Nyquist sampling constraints. At the receiver, the compressed data will be interpolated and compensated via being divided by the modulating function. We also present compression rate and analyze the resolution of a reconstructed image and the periodicity of harmonic interferences. Finally, we shows the validity of the proposed algorithm by simulation where a reconstructed image from undersampled data is compared with a reconstructed image obtained through decimatioin by modulating function, interpolation and compensation.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.15 no.6
• /
• pp.1037-1044
• /
• 2020

Since radar wind profiler (RWP) provides wind field data with high time and space resolution in all weather conditions, their verification of the accuracy and quality is essential. The simultaneous wind measurement from rawinsonde is commonly used to evaluate wind vectors from RWP. In this study, the simulation algorithm which produces the spectrum and raw time series (I/Q) data from the average values of moments is presented as a step-by-step verification method for the signal processing algorithm. The possibility of the simulation algorithm was also confirmed through comparison with the raw data of LAP-3000. The Doppler power spectrum was generated by assuming the density function of the skew-normal distribution and by using the moment values as the parameter. The simulated spectrum was generated through random numbers. In addition, the coherent averaged I/Q data was generated by random phase and inverse discrete Fourier transform, and raw I/Q data was generated through the Dirichlet distribution.