• Annual Conference on Human and Language Technology
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• 2004.10d
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• pp.20-24
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• 2004

본 논문에서는 환경 잡음과 원거리 음성 입력 그리고 노인 발화 등의 열악한 음성 인식 환경에서의 음성 언어이해(spoken language understanding)를 위한 정보 추출 접근 방식에 대해 논하고 있다. 정보 추출의 목적은 미리 정의된 slot에 적절한 값을 찾는 것이다. 음성 언어 이해를 위한 정보 추출은 필수적인 요소만을 추출하는 것을 목적으로 하는 개념 집어내기(concept spotting) 접근 방식을 사용한다. 이러한 방식은 미리 정의된 개념 구조 slot에만 관심을 가지기 때문에. 음성 언어 이해에서 사용되는 정보 추출은 언어를 완전히 이해한다기보다는 부분적으로 이해하는 방식을 취하고 있다. 음성 입력 언어는 주로 열등한 인식 환경에서 이루어지기 때문에 많은 인식 오류를 가지고 이로 인해 텍스트 입력에 비해 이해하기 어렵다. 이러한 점을 고려하여, 특정 정보에 집중함으로써 음성 언어를 이해하고자 시도하였다. 도로 정보 안내 영역을 대상으로 한 실험에서 텍스트 입력(WER 0%)과 음성 입력(WER 39.0%)이 주어졌을 때, 개념 집어내기 방식의 F-measure 값은 각각 0.945, 0.823을 나타내었다.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.78-80
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• 2006

전력계통망 및 수용가는 다양한 형태의 전력케이블 및 전력선이 연계된 분 배전망을 형성하고 있다. 특히, 이렇게 구성된 분 배전망은 하나의 전력계통으로서 연계된 전력망을 형성하고 있으며, 이를 전력선통신의 인프라로 활용할 수 있다. 최근 들어, 전력선통신 기술에 대한 연구가 활발히 진행되고 있으며, 계통에 연계된 부하와 분기선로 그리고 매질의 특성에 따라 통신환경이 달라진다. 특히 전송 주파수에 따른 신호의 감쇠, 연계된 부하의 종류와 이들 부하로 인한 잡음원의 유입 및 전송신호의 왜곡 등이 주요한 채널환경 요소이다. 본 논문에서는 상기 나열한 한계점을 극복하기 위한 대안으로 전력선 및 케이블의 매질특성을 평가하고, 이에 따른 전송신호의 영향을 분석, 연계된 다양한 부하들의 변동에 따른 통신환경의 변화 영향 그리고 통신성능에 미치는 영향을 분석하였으며, 또한 전력 케이블 및 선로의 특성과 부하변동 특성을 반영하여 구내용 전력케이블 기반의 UWB(Ultra Wide Band) 통신용 채널 환경을 모델링하는 방안을 제안하고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2C
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• pp.184-190
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• 2002

This paper compares and analyzes and analyzes the transmission performance of the OpenCable system and the DBD-C system which are adopted as the digital CATV transmission standard in U.S.A. and Europe respectively through computer simulation under the same channel environment. We considered the channel environment including the random noise and the CTB (Composite Tripple Beats) noise as channel impairments in order to compare the two standard fairly. Additionally, we analyzed the transmission performance of the OpenCable system for the various interleaving depths. We implemented each transmission system by software, and we analyzed BER values with respect to the C/N in order to compare their transmission performance. As a result of the computer simulation, to get the BER of ${10}^{-6}$ the OpenCable system requires 1.2 dB kiwer C/N than the DVB-C system in the 64-QAM mode, and the two system require similar C/N in the 256-QAM mode.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1376-1382
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• 2016

In this paper, we present a visual quality enhancement technique for conventional three-dimensional (3D) photon counting integral imaging using background noise removal algorithm. Photon counting imaging can detect a few photons from desired objects and visualize them under severely photon-starved conditions such as low light level environment. However, when a lot of photons are generated from background, it is difficult to detect photons from desired objects. Thus, the visual quality of the reconstructed image may be degraded. Therefore, in this paper, we propose a new photon counting imaging method that removes unnecessary background noise and detects photons from only desired objects. In addition, integral imaging can be used to obtain 3D information and visualize the 3D image by statistical estimations such as maximum likelihood estimation. To prove and evaluate our proposed method, we implement the optical experiment and calculate mean square error.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2844-2851
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• 2015

How to recover from the multiple 2D images into 3D object has been widely studied in the field of computer vision. In order to improve the accuracy of the recovered 3D shape, it is more important that noise must be minimized and the number of image frames must be guaranteed. However, potential noise is implied when tracking feature points. And the number of image frames which is consisted of an observation matrix usually decrease because of tracking failure, occlusions, or low image resolution, and so on. Therefore, it is obviously essential that the number of image frames must be secured by recovering the missing feature points under noise. Thus, we propose the analytic approach which can control directly the error distance and orientation of missing feature point by the geometrical properties under noise distribution. The superiority of proposed method is demonstrated through experimental results for synthetic and real object.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.188-194
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• 2014

The feature extraction mechanism of the CASA(Computational Auditory Scene Analysis) system uses time continuity and frequency channel similarity to compose a correlogram of auditory elements. In segmentation, we compose a binary mask by using cross-correlation function, mask 1(speech) has the same periodicity and synchronization. However, when there is delay between autocorrelation signals with the same periodicity, it is determined as a speech, which is considered to be a drawback. In this paper, we proposed an algorithm to improve discrimination of channel similarity using Weighted Cross-correlation in segmentation. We conducted experiments to evaluate the speech segregation performance of the CASA system in background noise(siren, machine, white, car, crowd) environments by changing SNR 5dB and 0dB. In this paper, we compared the proposed algorithm to the conventional algorithm. The performance of the proposed algorithm has been improved as following: improvement of 2.75dB at SNR 5dB and 4.84dB at SNR 0dB for background noise environment.

• The Journal of the Acoustical Society of Korea
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• v.33 no.5
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• pp.316-325
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• 2014

The basic unit of school is a classroom and the aural environment of the classrooms is essential factor for education purposes. Therefore, many efforts have been undertaken for enhancing the acoustical performance of the classrooms in many countries. As a result, acoustic criteria including reverberation time and background noise level have been established in US and UK for school classrooms depending on the usage and size of the rooms. However, in Korea, there has been little researches concerning the room acoustical investigations of the classrooms. The present study investigates the current situation of the aural environment of the 15 classrooms in Korea including elementary, middle and high schools. The acoustic criteria measured include RT, $D_{50}$, STI, SNR and background noise level. As the results, it was found that the background noise levels of the schools adjacent to roads exceed the US and UK standard of 35 dB(A). Also, most schools have so low SNR that they may be interfered by noise, which may affect speech transmission. It was also revealed that some schools have longer RT than the US standard of 0.6 s, but they all have high speech intelligibility.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.138-144
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• 2012

In this paper, we introduce the time-domain equalizer in orthogonal frequency division multiplexing (OFDM) systems using orthogonal matching pursuit (OMP) algorithm. Since OFDM system inserts guard intervals, it shows robust performance against multi-path fading. However, in Doppler channel, inter-carrier interference (ICI) occurs because an orthogonality of sub-carriers does not maintain. A least squares (LS) algorithm is common method of time-domain equalizer, but if a channel length is longer, the performance deteriorates by noise. The multi-path fading is a summation of the different delay signal. And that has sparse properties in time-domain. Because the OMP algorithm of the compressive sensing (CS) algorithm restores the channel by choosing the important elements of sparse channel, it can reduce the influence of noise. We simulate the performance of time-domain equalizer in OFDM system with various channel environments using OMP algorithm compared with other equalization method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1401-1410
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• 2017

Cryptographic synchronization which synchronizes internal state of cryptographic algorithm and ciphertext stream between an encryptor and a decryptor affects the quality of secure communication. If there happens a synchronization loss between a transmitter and a receiver in a secure communication, the output of the receiver is unintelligible until resynchronization is made. Especially, in the secure communication on a wireless channel with high BER, synchronization performance can dominate its quality. In this paper, we proposed a novel and noise robust synchronization signal generation method as well as its detection algorithm. We generated a synchronization signal in the form of a masking structure based on the maximal length sequence, and developed a detection algorithm using a correlation property of the maximal length sequence. Experimental results have demonstrated that the proposed synchronization signal outperforms the conventional concatenated type synchronization signal in a noisy environment.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.4
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• pp.494-499
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• 2012

In this paper, a new method for detecting various objects that can be risks to safety navigation in sea environment is proposed. By analysing Infrared(IR) images obtained from various sea environments, we could find out that object regions include both horizontal and vertical direction edges while background regions of sea surface mainly include vertical direction edges. Therefore, we present an approach to detecting object regions considering horizontal and vertical edges. To this end, in the first step, image enhancement is performed by suppressing noises such as sea glint and complex clutters using a statistical filter. In the second step, a horizontal edge map and a vertical edge map are generated by 1-D Discrete Cosine Transform technique. Then, a combined map integrating the horizontal and the vertical edge maps is generated. In the third step, candidate object regions are detected by a adaptive thresholding method. Finally, exact object regions are extracted by eliminating background and clutter regions based on morphological operation.