• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.226-229
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• 2001

Radio signal tracking has been developed especially in military as well as in other industries. It is necessary that an adaptive system trace the signal varying its PRI and frequency. In this paper we proposed a system to adapt various PRI and frequency using a neural network model named Error Back Propagation. Fist we prepared learning data by separating signal into time intervals and did some experiments with the teaming data. We found that the system had good effectiveness in tracing varying PRI and frequency signals.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.345-347
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• 1998

스캐너를 가지고 이미지를 스캔하면 RGB 값을 얻는다. 이 RGB 값은 스캐너의 빛을 인지하는 소자들의 하드웨어적인 특성이 더해진 장치 의존적인 값이다. 그래서 RGB 값은 왜곡된 칼라 정보를 가지고 있다. 그러므로 칼라 보정을 하기 위해서는 장치 독립적이 값으로 변환해야 한다. 본 논문에서는 장치 독립적인 값을 구하기 위해서 칼라 샘플들을 XYZ로 계측한 값과 400nm에서 700nm 사이의 파장을 계측한 분광 반사값(Spectral reflectance value)을 가지고 스캐너의 칼라 보정을 구현하였다. 구현 방법으로는 신경회로망의 오차 역전파(Error Back Propagation) 알고리즘을 사용하였고 두 가지의 데이터를 가지고 실험했을 때의 결과와 장단점을 비교하였다.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.737-738
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• 2008

An implementation of robust stereo matching algorithm under variable illumination conditions is presented in this paper. By applying window-based matchingmethod to global stereo matching algorthm using belief propagation, our implemented system shows low error rate and could efficiently cope with general radiometric disimilarities between images acquired from two different point of views.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.106-108
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• 2006

본 논문에서는 오버레이 네트워크 환경에서 비디오 스트리밍 서비스의 성능을 향상시키기 위한 수직 핸드오버 메커니즘을 제안한다. 본 논문에서는 error propagation 문제를 완화함으로써 비디오 스트리밍 서비스의 성능을 향상시킨다. 이를 위해 프레임들의 전송 경로를 유형별로 분리하고, 프레임들의 손실률을 최소화하는 재전송 정책을 사용하며, forced 수직 핸드오버 시 멀티캐스팅 방법을 사용하였다. 또한 stability period 정의하여 핑퐁 현상이 전송성능에 미치는 영향을 줄였다. 시뮬레이션을 통해 제안하는 방안이 error propagation 문제를 개선함으로써 이동 사용자에게 끊김없는 비디오 스트리밍 서비스를 제공함을 알 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1260-1266
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• 2007

Error propagation of source-relay (S-R) link limits the performance of decode-and-forward (DF) relay and prohibits DF relay from achieving full diversity gain. In order to solve this problem, the proposed deployment strategy focuses on two objectives. One is to achieve full diversity gain, and the other is to minimize the used power of the DF relay system. In order to achieve full diversity, the error probability of S-R link should be lower than that of maximal ratio combining (MRC) at destination without error propagation since the error probability of the weaker link dominates the total error probability. The proposed strategy of relay positioning points out the range of the relay position for achieving full diversity, and the used power of the relay is minimized by this range. Analysis of error probability and simulation results prove that the two objectives are achieved by the proposed strategy of the relay position.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.625-632
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• 2021

This paper studies the effect of the number of filters in the CNN (Convolutional Neural Network) layer on the performance of a noise attenuator. Speech is estimated from a noised speech signal using a 64-neuron, 16-kernel CNN filter and an error back-propagation algorithm. In this study, in order to verify the performance of the noise attenuator with respect to the number of filters, a program using Keras library was written and simulation was performed. As a result of simulation, it can be seen that this system has the smallest MSE (Mean Squared Error) and MAE (Mean Absolute Error) values when the number of filters is 16, and the performance is the lowest when there are 4 filters. And when there are more than 8 filters, it was shown that the MSE and MAE values do not differ significantly depending on the number of filters. From these results, it can be seen that about 8 or more filters must be used to express the characteristics of the speech signal.

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.05a
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• pp.62-63
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• 2001

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.2
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• pp.211-218
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• 1998

In this paper, we analyze various errors in prediction results of ray tracing propagation model for microcellular environments. It is shown that improper electrical parameters of building materials and limitations of diffraction orders can cause high errors in prediction results. Especially, the effect of errors in building database on prediction results is considered in detail. It is also shown that the prediction error increases as the resolution of building map data is getting worse, and the error is analyzed depending on LOS and NLOS domains. Based on the results obtained by the analysis developed in this paper, 5 m resolution is suitable for the building map data if the maximum prediction error is required to be below 6 dB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2365-2371
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• 1998

Discrete cosine transform (DCT) has wide applications in speech and image coding. In this paper, we propose a novel fast dCT scheme with the property of reduced multiplication stages and the smaller number of additions and multiplications. This exploits the symmetry property of the DCT kernel to decompose the N-point dCT to N/2 point, and can be generally applied recursively to $2^{m}$-point. The proposed algorithm has a structure that most of multiplications tend to be performed at final stage, and this reduces propagation of truncation error which could occur in the fixed-point computation. Also the minimization of the multiplication stages further decreases the error.

• Journal of the Korean Institute of Intelligent Systems
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• v.9 no.5
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• pp.490-495
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• 1999

In this paper. a learning method VoD-EBP for neural networks is proposed, which learn patterns by error back propagation. Based on Voronoi diagram, the method initializes the weights of the neural networks systematically, wh~ch results in faster learning speed and alleviated local optimum problem. The method also shows better the reliability of the design of neural network because proper number of hidden nodes are determined from the analysis of Voronoi diagram. For testing the performance, this paper shows the results of solving the XOR problem and the parity problem. The results were showed faster learning speed than ordinary error back propagation algorithm. In solving the problem, local optimum problems have not been observed.