• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.328-331
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• 2007

In this paper, the capacity of the clustered response model for correlated MIMO-OFDM fading channel is investigated. We compare the capacities achieved by correlation at receiver and achieved by correlation at both the transmitter and the receiver for the case where the channel is known and unknown at the transmitter are considered. It is found that the capacity achieved by correlation at receiver is better than the other. It is also shown that the capacity using the water-filling methed is larger than that using the uniform power allocation due to the water-filling gain. But it is negligible when the number of clusters is over the maximum rank of the sum correlation matrix and SNR is high.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.1
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• pp.39-43
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• 2012

60GHz band RF transceiver was made with the NRD waveguide structure for the point- to-point communication. A dielectric line that of comprising NRD waveguide was the milling process was not easy because a material gets soft, and also compression and expansion according to a temperature were serious, so this line was not suitable for the device in which the resonance characteristic was important. In addition, the thing for comprising amplification module was difficult in the NRD waveguide structure. In this paper, a way in which to overcome mentioned in upper part, the transceiver was made by below technology. Components in which the resonance characteristic was not important were made with the NRD waveguide hybrid IC, and components in which the resonance characteristic was important were made with waveguide. An amplifier packaged and modularizing the bare chip, it equipped at the NRD waveguide within. Manufactured transceiver communicated with FDD method, and it had 10dBm output power, and -60dBm minimum receive sensitivity.

• Korean Journal of Veterinary Research
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• v.44 no.2
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• pp.287-292
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• 2004

The objective of present study was to ascertain genetic diversity for cattle parentage testing. A total of 59 random cattle samples(29 Korean native cattle and 30 dairy cows) were genotyped by using 11 microsatellite loci(BM1824, BM2113, ETH10, ETH225, EH3, INRA23, SPS115, TGLA122, TGLA227, TGLA53, and TGLA126). This method consisted of multiplexing PCR procedure and showed reasonable amplification of all PCR products. Genotyping was performed with an ABI 310 genetic analyzer. The number of alleles per locus varied from 5 to 11 with a mean value of 6.73 in the Korean native cattle(KNC), 4 to 9 with a mean of 5.91 in dairy cows(DC). Expected heterozygosity was ranged 0.534~0.855(mean 0.732), 0.370~0.866(mean 0.692) in the KNC and DC, respectively. PIC value was ranged 0.485~0.821(mean 0.684), 0.336~0.834(mean 0.640) in the KNC and DC, respectively. Of the 11 markers, 7 markers(ETH10, EH3, INRA23, SPS115, TGLA122, TGLA227, TGLA53) and 3 markers(INRA23, TGLA227, TGLA53) have relatively high PIC value (>0.7) in the KNC and DC, respectively. The total exclusion probability of 11 microsatellite loci was 0.9997 and 0.9991 in the KNC and DC, respectively. These results present basic information for developing a system for parentage verification and individual identification in the KNC and DC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.8
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• pp.1911-1932
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• 2013

Orthogonal frequency-division multiplexing (OFDM) has become a popular modulation scheme for wireless protocols because of its spectral efficiency and robustness against multipath interference. Although the components of various OFDM protocols are functionally similar, they remain distinct because of the characteristics of the environment. Recently, graphics processing units (GPUs) have been used to accelerate the signal processing of the physical layer (PHY) because of their great computational power, high development efficiency, and flexibility. In this paper, we describe the implementation of parameterized baseband modules using GPUs for two different OFDM protocols, namely, 802.11a and 802.16. First, we introduce various modules in the modulator/demodulator parts of the transmitter and receiver and analyze the computational complexity of each module. We then describe the integration of the GPU-based baseband modules of the two protocols using the parameterized method. GPU-based implementations are addressed to explain how to accelerate the baseband processing to archive real-time throughput. Finally, the performance results of each signal processing module are evaluated and analyzed. The experiments show that the GPU-based 802.11a and 802.16 PHY meet the real-time requirement and demonstrate good bit error ratio (BER) performance. The performance comparison indicates that our GPU-based implemented modules have better flexibility and throughput to the current ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1185-1190
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• 2008

In this paper, we propose an simplified successive minimum mean square error ($S^{2}MMSE$) algorithm that can simplify the computational complexity for precoding matrix generation in the successive minimum mean square error (SMMSE) precoding method, which is adopted as a multiuser multiple-input multiple-output (MU-MIMO) precoding technique in the IST (information society technologies)-WINNER (wireless world initiative new radio) project. The original algorithm generates the precoding matrix by calculating all individual precoding vectors with each requiring its own MMSE nulling matrix, over all receive antennas for all users. In contrast, this proposed algorithm first calculates the MMSE nulling matrix for each user, and then calculates all precoding vectors for respective receive antennas of the corresponding user by using the identical MMSE nulling matrix, in which only a simple matrix-vector multiplication is required for each vector. Consequently, it can simplify significantly the computational complexity to generate a precoding matrix for SMMSE precoding.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.266-274
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• 2005

We have designed photonic crystal based bandpass filters whose characteristics are suitable for WDM communication system. The filters consist of coupled point defect resonators in two-dimensional photonic crystal. The frequency response of coupled resonators has been analyzed by the coupling of modes in time, from which the design parameters for the coupled resonator filters have been extracted. For the appropriate choice of the design parameters, each resonator is treated as a lumped L-C resonance circuit, and from the analogy between the equivalent circuit and the standard L-C filter circuits, the design parameters are simply determined from the table for general filter circuit design. Based on the determined design parameters, a photonic crystal based filter has been designed and its performance has been calculated using the finite-difference time-domain method. The designed filter shows a pass band of 50GHz and 0.5 dB in-band ripple, which is suitable for typical WDM communication systems with 100GHz channel spacing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6A
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• pp.399-408
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• 2011

Development of smart sensors for structural health monitoring and damage detection has been advanced remarkably in recent years. Nowadays fiber optic sensors, especially fiber Bragg grating (FBG) sensors, have attracted many researchers' interests for their attractive features, such as multiplexing capability, durability, lightweight, electromagnetic interference immunity. In this paper, a damage detection approach of jacket-type offshore structures by principal component analysis (PCA) technique using FBG sensors are presented. An experimental study for a tidal current power plant structure as one of the jacket-type offshore structures was conducted to investigate the feasibility of the proposed method for damage monitoring. It has been found that the PCA technique can efficiently eliminate environmental effects from measured data by FBG sensors, resulting more damage-sensitive features under various environmental variations.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.6
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• pp.1455-1461
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• 2012

MIMO-OFDM which is one of core techniques for the high-speed mobile communication system requires the efficient channel estimation method with low estimation error and computational complexity, for accurately receiving data. In this paper, we propose a channel estimation algorithm with low channel estimation error comparing with LS which is primarily employed to the MIMO-OFDM system, and with low computational complexity comparing with MMSE. The proposed algorithm estimates channel vectors based on the LMS adaptive algorithm in the time domain, and the estimated channel vector is sent to the detector after FFT. We also suggest a preamble architecture for the proposed MIMO-OFDM channel estimation algorithm. The computer simulation example is provided to illustrate the performance of the proposed algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.6
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• pp.1234-1242
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• 2004

In this paper, the characteristics of compensation for interferenced mid-channel signal by neighbor channels through four-wave mixing (FWM) process dominantly is investigated as a function of channel input power, fiber dispersion coefficient and transmission length in WDM system with equally spaced channels. The compensation method used in this research is mid-span spectral inversion(MSSI). The highly nonlinear dispersion shifted fiber (HNL-DSF) is used as a nonlinear medium of optical phase conjugator (OPC) in order to compensate wideband WDM signals. First, we confirmed that the effect of FWM on channel interference is gradually reduced as fiber dispersion coefficient becomes gradually smaller, independent of signal format. And, we confirmed that RZ is better than NRZ as a modulation format for transmitting high power channel with allowable reception quality. But realization of flexible WDM systems regardless of channel number variation is possible by using NRZ rather than RZ format.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.205-213
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• 2011

The Long Term Evolution (LTE) system is designed to provide a high quality data service for fast moving mobile users. It is based on the Orthogonal Frequency Division Multiplexing (OFDM) and relies its channel estimation on the training samples which are systematically built within the transmitting data. Either a preamble or a lattice type is used for the distribution of training samples and the latter suits better for the multipath fading channel environment whose channel frequency response (CFR) fluctuates rapidly with time. In the lattice-type structure, the estimation of the CFR makes use of the least squares estimate (LSE) for each pilot samples, followed by an interpolation both in time-and in frequency-domain to fill up the channel estimates for subcarriers corresponding to data samples. All interpolation schemes should rely on the pilot estimates only, and thus, their performances are bounded by the quality of pilot estimates. However, the additive noise give rise to high fluctuation on the pilot estimates, especially in a communication environment with low signal-to-noise ratio. These high fluctuations could be monitored in the alternating high values of the first forward differences (FFD) between pilot estimates. In this paper, we analyzed statistically those FFD values and propose a postprocessing algorithm to suppress high fluctuations in the noisy pilot estimates. The proposed method is based on a localized adaptive moving-average filtering. The performance of the proposed technique is verified on a multipath environment suggested on a 3GPP LTE specification. It is shown that the mean-squared error (MSE) between the actual CFR and pilot estimates could be reduced up to 68% from the noisy pilot estimates.