• Journal of Convergence for Information Technology
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• v.7 no.2
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• pp.53-58
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• 2017

This paper describes the design of a simulator for analyzing the accuracy of a correlative interferometer(CI) direction finder. CI direction finder is robust to noise, so it is often used in aircraft or ships where complex antenna installation is required, and the direction finding accuracy is very high. When the radio wave is incident at a specific azimuth angle, the phase difference calculated in a noiseless environment and the phase difference measured in a real environment with noise are fused to estimate the largest correlation coefficient as the azimuth angle of the radio wave. The simulator receives RF frequency, the number of antennas, the antenna coordinates, the transmission signal intensity, the bandwidth of the receiver, the gain and the payload effect, and calculates the direction finding accuracy of 0-360 degrees azimuth and 0-60 degree elevation with 0.5 degree. accuracy.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.416-421
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• 2008

Recent high-speed trains around the world have achieved remarkable improvement in speed. In Korea, the new high-speed train with maximum speed of 400km/h has been developing through the 'Future High-Speed Rail System Project'. The improvement in train speed brings numerous aerodynamic problems such as strong aerodynamic resistance, noise, drastic pressure variation due to the crosswind or passing by, micro-pressure wave at tunnel exit, and so on. Especially, the nose shape of high-speed train is closely related to the most of the aerodynamic problems. Also the pantograph has to be considered for noise prevention and detachment problems. In this paper, the project, 'Research on the Aerodynamic Technology Advancement of the High-Speed EMU' is introduced briefly, which is one of the efforts for the speed improvement of the 'HEMU400x'. Finally, two main results of train nose and pantograph will be shown. First, the optimization of the cross-sectional area distribution of the high-speed train nose to reduce tunnel micro-pressure wave, and second, robust design optimization of the panhead shape of a pantograph.

• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.506-511
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• 2018

This paper proposes an GMM(Gaussian Mixture Model)-DNN(Deep Neural Network) hybrid-based feature compensation method for effective speech recognition in noisy environments. In the proposed algorithm, the posterior probability for the conventional GMM-based feature compensation method is calculated using DNN. The experimental results using the Aurora 2.0 framework and database demonstrate that the proposed GMM-DNN hybrid-based feature compensation method shows more effective in Known and Unknown noisy environments compared to the GMM-based method. In particular, the experiments of the Unknown environments show 9.13 % of relative improvement in the average of WER (Word Error Rate) and considerable improvements in lower SNR (Signal to Noise Ratio) conditions such as 0 and 5 dB SNR.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.67-72
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• 2021

This paper compare the adative equalization performance of the DSE-MMA (Dithered Signed-Error MMA) and QE-MMA (Quantized-Error MMA) which has a simplifies the computational operation of currently used MMA algorithm. The DSE-MMA possible to improve the rubustness to noise by using the dithered signal consider the polarity of error signal in the multiplication part. In QE-MMA, it use the polarity of error signal after performing the nonlinear power-of-two quantizing operation for easiness of H/W implementation. The same channel environment was applied, and it's performance of the output signal constellation, the residual isi and maximum distortion and MSE that means the convergence characteristics, the SER that means the robustness of external noise of algorithm were compared and evaluated. As a result of computer simulation, the QE-MMA has more good in constellation, residual isi, maximum distortion, MSE performanc than DSE-MMA. In SER, the DSE-MMA has more robust due to dither signal than QE-MMA.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.3
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• pp.398-404
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• 2020

In this paper, we propose a new design method of signal constellation of the spiral quadrature amplitude modulation (QAM) exploiting a modified gradient descent search algorithm and its binary mapping rule. Unlike the conventional method, the new method, which uses and the constellation optimization algorithm and the maximum number of iterations as a parameter for the iterative design, is more robust to phase noise. And the proposed binary mapping rule significantly reduces the average Hamming distance of the spiral constellation. As a result, the proposed spiral QAM constellation has much improved error performance compared to the conventional ones even in a very severe phase noise environment. It is, therefore, considered that the proposed QAM may be a useful modulation format for coherent optical communication systems and orthogonal frequency division multiplexing (OFDM) systems.

• Journal of Advanced Navigation Technology
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• v.26 no.3
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• pp.166-171
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• 2022

In this paper, we propose an algorithm to improve DoA(direction of arrival) estimation performance of the subspace-based method by generating high robustness correlation matrix of the signals incident on the uniformly linear array antenna. The existing subspace-based DoA estimation method estimates the DoA by obtaining a correlation matrix and dividing it into a signal subspace and a noise subspace. However, the component of the correlation matrix obtained from the low SNR and small number of snapshots inaccurately estimates the signal subspace due to the noise component of the antenna, thereby degrading the DoA estimation performance. Therefore a robust correlation matrix is generated by arranging virtual signal vectors obtained from the existing correlation matrix in a sliding manner. As a result of simulation using MUSIC and ESPRIT, which are representative subspace-based methods,, the computational complexity increased by less than 2.5% compared to the existing correlation matrix, but both MUSIC and ESPRIT based on RMSE 1° showed superior DoA estimation performance with an SNR of 3dB or more.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.4
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• pp.31-39
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• 2021

In this paper, warpage analysis that separates PCB for PoP (Package on Package) into unit and substrate using FEM (Finite Element Method), analysis of the effect of layer thickness on warpage, and SN (Signal-to-Noise) ratio by Taguchi method was carried. According to the analysis result, the contribution of the circuit layer on warpage was very high in the unit PCB, and the contribution of the outer layer was particularly high. On the other hand, the substrate PCB had a high influence of the circuit layer on warpage, but it was relatively low compared to the unit PCB, and the influence of the solder resist was rather increased. Therefore, considering the unit PCB and the substrate PCB at the same time, it is desirable to design the PCB for PoP layer-by-layer structure so that the outer and inner circuit layers are thick, the top solder resist is thin, and the thickness of the bottom solder resist is between 5 ㎛ and 25 ㎛.

• The Journal of the Acoustical Society of Korea
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• v.29 no.6
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• pp.374-380
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• 2010

It is known that the problem of FIR filtering with noisy input and output data can be solved by a total least squares (TLS) estimation. It is also known that the performance of the TLS estimation is very sensitive to the ratio between the variances of the input and output noises. In this paper, we propose a convex combination algorithm between the ordinary recursive LS based TLS (RTLS) and the ordinary recursive LS (RLS). This combined algorithm is robust to the noise variance ratio and has almost the same complexity as the RTLS. Simulation results show that the proposed algorithm performs near TLS in noise variance ratio ${\gamma}{\approx}1$ and that it outperforms TLS and LS in the rage of 2 < $\gamma$ < 20. Consequently, the practical workability of the TLS method applied to noisy data has been significantly broadened.

• Journal of Korea Society of Industrial Information Systems
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• v.29 no.4
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• pp.13-24
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• 2024

In this paper, we analyzed the performance of normalization according to various neural network models and input-output structures. For the analysis, a simulation-based dataset for noise environments with homogeneous and up to three interfering signals was used. As a result, the end-to-end structure that directly outputs noise variance showed superior performance when using a 1-D convolutional neural network and BiLSTM model, and was analyzed to be particularly robust against interference signals. This is because the 1-D convolutional neural network and bidirectional long short-term memory models have stronger inductive bias than the multilayer perceptron and transformer models. The analysis of this paper are expected to be used as a useful reference for future research on deep learning-based normalization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.527-530
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• 2008

The watermarking method was suggested to protect the right of the copyright and the right of property, data loss is yes or not, copy prevention and pursuit about the brainchild(music, image, video and so on) in the early 1990. In this paper, we suggest the watermarking algorithm against the geometrical transformation of the medical images applied the Watershed algorithm. The robust watermarking methodology is being suggested using the several algorithm against the attacks such as compression, filtering, noise and geometrical transformation of the medical image.