• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2805-2812
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• 2015

For the purpose of estimation of time variant frequency selective transmission channels, reference symbols are usually employed. The bit error performance of LTE OFDM systems is analyzed in the case of LTE standard reference symbol arrangement. Results show that LTE OFDM system with this LTE reference symbol arrangement is robust against Doppler time variant fading. However, the performance of that system is degraded due to channel estimation error in frequency domain. An equidistant arrangement with a diamond shape structure of reference symbols, however having 4 subcarriers distance in frequency domain, is suggested for the optimal channel estimation.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.3
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• pp.311-317
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• 1998

A total of 1033 Brown Swiss and 610 Canadienne cows were phenotyped for the genetic variants ${\alpha}_{s1}$-casein, ${\beta}$-casein, ${\kappa}$-casein, ${\beta}$-lactoglobulin and ${\alpha}$-lactalbumin. In Brown Swiss, frequency distributions were: 97.3% B and 2.7% C variant of ${\alpha}_{s1}$-casein; 31.6% $A^1$, 51.8% $A^2$, 0.5% $A^3$ and 16.1% B variant of ${\beta}$-casein; 70.4% A, 29.3% B, and 0.3% C variant of ${\kappa}$-casein; 41.7% A and 58.3% B variant of ${\beta}$-lactoglobulin; and 100% B variant of ${\alpha}$-lactalbumin. Corresponding frequencies in Canadienne for those five milk proteins were: 98.6 and 1.4%;58.5, 33.5, 0.08 and 7.9%; 78.8, 21.1 and 0.1%, 42.4 and 57.6%; and 100%. Analysis of variance by least squares showed possible association between milk protein phenotypes and some lactational production traits. There were no significant association of phenotypes of ${\alpha}_{s1}$-casein, ${\beta}$-casein and ${\beta}$-lactoglobulin with milk yield, fat yield, protein yield, fat percentage and protein percentage in both breeds during the three lactations. In the Brown Swiss, ${\kappa}$-casein phenotype was associated with 305-day fat yield and protein yield during the first lactation. ${\kappa}$-Casein AB was associated with higher milk, fat and protein yield during the second lactation. During the third lactation, ${\beta}$-lactoglobulin AA in Canadienne cows was associated with higher protein content in the milk (3.70%) when compared to phenotypes AB (3.54%) and BB (3.64%).

• Environmental Mutagens and Carcinogens
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• v.21 no.2
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• pp.149-155
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• 2001

Eighty-one workers including 38 employees directly incinerating industry wastes were recruited from a company located in South Korea. To evaluate the association between urinary 1-hydroxypyrene glucuronide (1-OHPG) levels, as internal dose of polycyclic aromatic hydrocarbon (PAH) exposure, and glycophorin A (GPA) mutation frequency, as an early biologic effect indicator. Urinary 1-OHPG levels were measured by synchronous fluorescence spectroscopy after immunoaffinity purification using monoclonal antibody 8E11. Erythrocyte GPA variant frequency (NN or NO) was assessed in MN heterozygotes with a flow cytometic assay. The GSTM1 and GSTT1 genotypes were assessed by a multiplex PCR method. The GPA NN phenotype frequency was higher in occupationally exposed group (n=14, mean$\pm$S.D. 6.6$\pm$12.0 in 10/SUP 6/ erythrocyte cells) than in non-exposed group (n=22, 2.1$\pm$3.5). Similarly, the GPA(NO or NN) phenotype frequency was higher in exposed group (n=14, 9.7$\pm$17.3) than non-exposed group (n=22, 4.2$\pm$6.3). The above differences failed to reach statistical significance, but a significant increase was seen in GPA variant frequency levels with increase in urinary 1-OHPG levels (Spearman's correlation: p=0.06 (NO), p=0.07 (NO or NN)). When this association was evaluated by GSTM1 genotype status, the association between GPA mutation and urinary 1-OHPG levels was stronger in individuals with GSTM1 present genotype (Spearmans correlation; r=0.50, p=0.02). These results suggest that the association between urinary 1-OHPG and GPA mutation is be modulated by the GSTM1 genotype.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.6
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• pp.596-602
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• 2013

In general, existed vibration energy harvester is optimum in electronic energy gleaned from vibration energy with fixed single frequency, because it is using resonance. But it is limit in electronic energy gleaned from ocean wave energy with variant frequency. This paper studied for width band vibration energy harvester that obtains electronic energy from ocean wave with infinite vibration energy in order to solve it. It is composed of buoy to occur resonance in the center frequency of ocean wave energy and the vibration system to occur resonance in the same frequency. As a result, existed vibration energy harvester using resonance maximized electronic energy conversion efficiency in single frequency, while proposed width band vibration energy harvester has merit that maximized electronic energy conversion efficiency in ocean wave with variant frequency.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.12
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• pp.544-548
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• 2006

The instantaneous frequency gives a frequency value at a time instance. Thus, it is natural to use the instantaneous frequency for detecting disturbances of voltage signal in power line. Various instantaneous frequency estimators are introduced. By applying to different types of disturbed signals, we show the estimators' ability to classify flickers. Also, the computational costs are compared between different instantaneous frequency estimators. The Prony's method (PRONY) and the modified covariance method (MCOV) need relatively smaller amount of calculation than the Teaser-Kaiser energy operator based estimator (DESA II). For an AM-FM modulated signal, the tracking performance of different instantaneous frequency estimators is also compared. Through simulation, it is shown that MCOV produces less variant frequency estimation values than DESA II and PRONY method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.256-268
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• 2008

This paper proposes an efficient scheme to track the time variant channel induced by multi-path Rayleigh fading in mobile wireless Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems with null sub-carriers. In the proposed method, a blind channel response predictor is designed to cope with the time variant channel. The proposed channel tracking scheme consists of a frequency domain estimation approach that is coupled with a Minimum Mean Square Error (MMSE) time domain estimation method, and does not require any matrix inverse calculation during each OFDM symbol. The main attributes of the proposed scheme are its reduced computational complexity and good tracking performance of channel variations. The simulation results show that the proposed method exhibits superior performance than the conventional channel tracking method [4] in time varying channel environments. At a Doppler frequency of 100Hz and bit error rates (BER) of 10-4, signal-to-noise power ratio (Eb/N0) gains of about 2.5dB are achieved relative to the conventional channel tracking method [4]. At a Doppler frequency of 200Hz, the performance difference between the proposed method and conventional one becomes much larger.

• Korean Journal of Biological Psychiatry
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• v.12 no.2
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• pp.196-206
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• 2005

Objectives:The purpose of this study is to evaluate the pathophysiology of alcoholics by investigating the differences in frequency of Aldehyde Dehydrogenase 2(ALDH2) genotypes and ALDH2 alleles between patients with alcohol dependence and controls, and the differences of drinking and personality traits in Korean male alcoholics with ALDH2 genotype variances. Methods:The authors selected 98 patients with alcohol dependence and 53 controls. Self-report questionnaires for acute reponses after alcohol ingestion, the AUI(Alcohol Use Inventory), and the NEO-PI-R(NEO Personality Inventory Revised) were given to all patients with alcohol dependence. ALDH2 genotypes were typed with MboII RFLP(Restriction Fragment Length Polymorphism) method in 53 controls and 98 patients with alcohol dependence. The authors divided alcoholic patients into two groups according to the presence of variant $ALDH2^2$ allele;normal ALDH2 alcoholics(N=87) and variant ALDH2 alcoholics(N=11). Results:1) The genotypic frequencies of subjects with $ALDH2^{1/1}$ were higher and those with $ALDH2^{1/2}$ and $ALDH2^{2/2}$ were lower in patients than in controls. 2) Alcohol dependence could be found in $ALDH2^{2/2}$ homozygote individuals. 3) Variant ALDH2 alcoholics had more family problems in the AUI than normal ALDH2 alcoholics. 4) Variant ALDH2 alcoholics experienced more flushing and cardiovascular responses after alcohol ingestion than normal ALDH2 alcoholics. 5) Variant ALDH2 alcoholics had less altruistic personality traits in the NEO-PI-R than normal ALDH2 alcoholics. 6) Variant ALDH2 alcoholics tended to have more tolerance to alcohol than normal ALDH2 alcoholics. Conclusion:Variant $ALDH2^2$ allele might play a protective role in the pathogenesis of alcohol dependence and there were several significant differences of drinking and personality traits in Korean male alcoholics with ALDH2 genotype variances.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.248-251
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• 2014

We develop the signal processing method for implementing the human perceptual variant on frequency and space. The human visual perceptual sensitivity varies as frequency components and the human perceivable resolution diminishes as the distances further from the eye-focused point. For realizing the frequency sensitivity, we developed the signal direction adaptive multiband energy scaling method to weight the frequency components. The low-pass filtering is designed on the developed energy scaling method for diminishing perceivable resolutions as the deviated distance from the eye-focused point. The developed method not only enhances the frequency components of image signals at the eye-focused region but also smoothes non-perceivable detailed image signals at non-focused regions. The proposed method is verified by the subjective and objective evaluations that it can improve human perceptual visual quality.

• Geomechanics and Engineering
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• v.13 no.1
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• pp.161-171
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• 2017

The underlying ground state of a railway plays a significant role in maintaining the integrity of the overlying concrete slab and ultimately supporting the train load. While effective nondestructive tests have been used to evaluate the rail track system, they can only be performed during non-operating time due to the stress wave generated by active sources. In this study, finite element numerical simulations are conducted to investigate the feasibility of detecting unfavorable substructure conditions by using a moving train load. First, a train load module is developed by converting the train load into time-variant equivalent forces. The moving forces based on the shape functions are applied at the nodes. A parametric study that takes into account the bonding state and the train class is then performed. All the synthetic signals obtained from numerical simulations are analyzed at the frequency domain using a Fast Fourier transform (FFT) and at the time-frequency domain using a Short-Time Fourier transform (STFT). The presence of a void condition amplifies the acceleration amplitude and the vibration response. This study confirms the feasibility of using a moving train load to systematically evaluate a rail track system.

• Structural Engineering and Mechanics
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• v.69 no.1
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• pp.21-31
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• 2019

Optimizing composite structures to exploit their maximum potential is a realistic application with promising returns. In this research, simultaneous maximization of the fundamental frequency and frequency separation between the first two modes by optimizing the fiber angles is considered. A high-fidelity design optimization methodology is developed by combining the high-accuracy of finite element method with iterative improvement capability of metaheuristic algorithms. Three powerful nature-inspired optimization algorithms viz. a genetic algorithm (GA), a particle swarm optimization (PSO) variant and a cuckoo search (CS) variant are used. Advanced memetic features are incorporated in the PSO and CS to form their respective variants-RPSOLC (repulsive particle swarm optimization with local search and chaotic perturbation) and CHP (co-evolutionary host-parasite). A comprehensive set of benchmark solutions on several new problems are reported. Statistical tests and comprehensive assessment of the predicted results show CHP comprehensively outperforms RPSOLC and GA, while RPSOLC has a little superiority over GA. Extensive simulations show that the on repeated trials of the same experiment, CHP has very low variability. About 50% fewer variations are seen in RPSOLC as compared to GA on repeated trials.