• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2179-2188
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• 2015

Recently, many researches have been done to solve the challenging problem of Blind Source Separation (BSS) problems in the underdetermined cases, and the “Two-step” method is widely used, which estimates the mixing matrix first and then extracts the sources. To estimate the mixing matrix, conventional algorithms such as Single-Source-Points (SSPs) detection only exploits the sparsity of original signals. This paper proposes a new underdetermined mixing matrix estimation method for time-delayed mixtures based on the receiver prior exploitation. The prior information is extracted from the specific structure of the complex-valued mixing matrix, which is used to derive a special criterion to determine the SSPs. Moreover, after selecting the SSPs, Agglomerative Hierarchical Clustering (AHC) is used to automaticly cluster, suppress, and estimate all the elements of mixing matrix. Finally, a convex-model based subspace method is applied for signal separation. Simulation results show that the proposed algorithm can estimate the mixing matrix and extract the original source signals with higher accuracy especially in low SNR environments, and does not need the number of sources before hand, which is more reliable in the real non-cooperative environment.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.4
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• pp.233-239
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• 2003

For the quantitative analysis of an unknown sample a calibration curve should be obtained, as analytical instruments give relative, rather than absolute measurements. Therefore, researchers should make standard samples with various known concentrations, measure each standard and the unknown sample, and then determine the concentration of the unknown by comparing the measured value to those of the standards. These procedures are tedious and time-consuming. Therefore, we developed a polymer based microfluidic device from polydimethylsiloxane, which integrates serial dilution and capillary electrophoresis functions in a single device. The integrated microchip can provide a one-step analytical tool, and thus replace the complex experimental procedures. Two plastic syringes, one containing a buffer solution and the other a standard solution, were connected to two inlet holes on a microchip, and pushed by a hydrodynamic force. The standard sample is serially diluted to various concentrations through the microfluidic networks. The diluted samples are sequentially introduced through microchannels by electro-osmotic force, and their laser-induced fluorescence signals measured by capillary electrophoresis. We demonstrate the integrated microchip performance by measuring the fluorescence signals of fluorescein at various concentrations. The calibration curve obtained from the electropherograms showed the expected linearity.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.3
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• pp.336-341
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• 2004

This paper proposes an independent component analysis(ICA) of the fixed-point (FP) algorithm based on secant method and the kurtosis. The FP algorithm based on secant method is applied to improve the analysis speed and performance by simplifying the calculation process of the complex derivative in Newton method, the kurtosis is applied to cluster the components. The proposed ICA has been applied to the problems for separating the 6-mixed signals of 500 samples and 8-mixed images of $512{\times}512$ pixels, respectively. The experimental results show that the proposed ICA has always a fixed analysis sequence. The result can be solved the limit of conventional ICA based on secant method which has a variable sequence depending on the running of algorithm. Especially, the proposed ICA can be used for classifying and identifying the signals or the images.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.95-106
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• 2017

In this paper, we investigate the conventional topological interference management (TIM) with proposed network topology such as 8 trigram (8 user networks). The key observation is that optimal symmetric degree of freedom (DoF) can be achieved for 8 user network with different channel coherence times by adaptively selecting the interference alignment scheme via controlling the alignment feasibility of the transmitted signals. However, this yields a very complex problem, for which we use the combination of different schemes such as interference avoidance and repetition coding. In addition to the above schemes, we propose a triangular transmit cooperation (TTC) algorithm for 8 user networks to achieve the optimal symmetric DoF. And We apply the principle of complementarity of 8 trigram to remove the interferences, and correspond the concepts of win-win and conflict to direct and indirect signals of transmit and receive respectively. We find that the principle of complementarity comes out from the trigram of I Ching. That is, we apply the relation of confrontation and coexistence to 8 transmitters and receivers, and get the results of symmetric DoF of 4/3.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.357-359
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• 2009

In this paper, the 2.4GHz doppler radar system consisting of the doppler radar module and a baseband module were designed to detect heartbeat and respiration signal without direct skin contact. A bio-radar system emits continuous RF signal of 2.4GHz toward human chest, and then detects the reflected signal so as to investigate cardiopulmonary activities. The heartbeat and respiration signals acquired from quadrature signal of the doppler radar system are applied to the pre-processing circuit, amplification circuit, and the offset circuit of the baseband module. ECG(electrocardiogram) and reference respiration signals are measured simultaneously to evaluate the doppler radar system. As a result, the respiration signal of doppler radar signal is detected to 1m without complex digital signal processing. The sensitivity and calculated from I/Q respiration signal were $98.29{\pm}1.79%$, $97.11{\pm}2.75%$, respectively, and positive predictivity were $98.11{\pm}1.45%$, $92.21{\pm}10.92%$, respectively. The sensitivity and positive predictivity calculated from phase and magnitude of the doppler radar were $95.17{\pm}5.33%$, $94.99{\pm}5.43%$, respectively. In this paper, we confirmed that noncontact real-time heartbeat and respiration detection using the doppler radar system has the possibility and limitation.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.535-538
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• 1990

The main problem in speech recognition is the enormous variability in acoustic signals due to complex but predictable contextual effects. Especially in plosive consonants it is very difficult to find invariant cue due to various contextual effects, but humans use these contextual effects as helpful information in plosive consonant recognition. In this paper we experimented on three artificial neural net models for the recognition of plosive consonants. Neural Net Model I used "Multi-layer Perceptron ". Model II used a variation of the "Self-organizing Feature Map Model". And Model III used "Interactive and Competitive Model" to experiment contextual effects. The recognition experiment was performed on 9 Korean plosive consonants. We used VCV speech chains for the experiment on contextual effects. The speech chain consists of Korean plosive consonants /g, d, b, K, T, P, k, t, p/ (/ㄱ, ㄷ, ㅂ, ㄲ, ㄸ, ㅃ, ㅋ, ㅌ, ㅍ/) and eight Korean monothongs. The inputs to Neural Net Models were several temporal cues - duration of the silence, transition and vot -, and the extent of the VC formant transitions to the presence of voicing energy during closure, burst intensity, presence of asperation, amount of low frequency energy present at voicing onset, and CV formant transition extent from the acoustic signals. Model I showed about 55 - 67 %, Model II showed about 60%, and Model III showed about 67% recognition rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.360-370
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• 2010

In this paper, a distributed beamforming problem is considered in an amplify-and-forward (AF) wireless relay network consist of multiple source-destination pairs and relaying nodes. To exploit degree of freedom of the number of beamformers, in the first step, we proposed that the sources transmit their signals through orthogonal channels. During the second step, the relays transmit their received signals multiplied by complex weights to amplify and compensate for phase changes introduced by the backward channels through one common channel. The optimal beamforming vectors are obtained through minimization of the total relay transmit power while the signal-to-interference-plus-noise ratios (SINRs) at the destinations are above certain thresholds to meet a quality of services (QoSs) level. In the numerical example, it is shown that the proposed scheme needs less transmit power for moderate network data rates than other schemes, such as space division multiplexing or time-division multiplexing scheme.

• Safety and Health at Work
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• v.3 no.2
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• pp.92-100
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• 2012

Objectives: The French National Occupational Diseases Surveillance and Prevention Network (RNV3P) is a French network of occupational disease specialists, which collects, in standardised coded reports, all cases where a physician of any specialty, referred a patient to a university occupational disease centre, to establish the relation between the disease observed and occupational exposures, independently of statutory considerations related to compensation. The objective is to compare the relevance of disproportionality measures, widely used in pharmacovigilance, for the detection of potentially new disease ${\times}$ exposure associations in RNV3P database (by analogy with the detection of potentially new health event ${\times}$ drug associations in the spontaneous reporting databases from pharmacovigilance). Methods: 2001-2009 data from RNV3P are used (81,132 observations leading to 11,627 disease ${\times}$ exposure associations). The structure of RNV3P database is compared with the ones of pharmacovigilance databases. Seven disproportionality metrics are tested and their results, notably in terms of ranking the disease ${\times}$ exposure associations, are compared. Results: RNV3P and pharmacovigilance databases showed similar structure. Frequentist methods (proportional reporting ratio [PRR], reporting odds ratio [ROR]) and a Bayesian one (known as BCPNN for "Bayesian Confidence Propagation Neural Network") show a rather similar behaviour on our data, conversely to other methods (as Poisson). Finally the PRR method was chosen, because more complex methods did not show a greater value with the RNV3P data. Accordingly, a procedure for detecting signals with PRR method, automatic triage for exclusion of associations already known, and then investigating these signals is suggested. Conclusion: This procedure may be seen as a first step of hypothesis generation before launching epidemiological and/or experimental studies.

• Geophysics and Geophysical Exploration
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• v.4 no.2
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• pp.34-44
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• 2001

Forward modeling by construction of synthetic data is usually practiced in a horizontal surface and a few subsurface structures. However, in-situ surveys often take place in such topographic changes that the corrupted field data always make it difficult to interpret the right signals. To examine the propagation characteristic of elastic waves on the irregular surface, a general mesh generation code for finite element method was modified to consider the topography. By implementing this algorithm, the time domain modeling was practiced in some models with surface topography such as mound, channel, etc. The synthetic data obtained by receivers placed on surface also agreed with the analytic solution. The snapshots showing the total wave-field revealed the propagation characteristic of the elastic waves through complex subsurface structures and helped to identify the signals on the time traces. The transmission of Rayleigh waves along the surface, compressive waves, and sheer waves was observed. Moreover, it turned out that the Rayleigh waves behave like a new source at the edge.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.10
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• pp.1-9
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• 1999

In this paper, a subblock partition scheme for reduction of computational complexity in partial transmit sequence which reduces the peak-to-average power ratio in orthogonal frequency division multiplexing (OFDM) is proposed. In this scheme, complex signals are assigned into partial subbands randomly and signals in a partial subband are duplicated and concatenated repetitively to make a subblock. By modulation of active subbands which have almost interleaved pattern, computational complexity can be reduced. As results of computer simulation, the proposed shows almost same peak to average power ratio reduction performance as compared to the conventional one. However, computational complexity required to transmit a partial transmit sequence OFDM symbol has been reduced extensively.