Effects of Traffic Signals with a Countdown Indicator

Joonho Chang,Kihyo Jung 대한인간공학회 2017 大韓人間工學會誌 Vol.36 No.5

Objective: This study examined two traffic signals with a countdown indicator in terms of driver"s reaction time and subjective satisfaction score and their performance was compared with a standard traffic signal in driving simulation. Background: Dilemma zone is created when a traffic light changes at intersections. It often pushes drivers to rush in urgent and premature decision making whether to go or stop and thus induces unnecessary mental load among drivers, which may lead to sudden conflicts with following vehicles at intersections. Method: Forty college students (male: 20, female: 20) participated in this driving simulation study. Three traffic signals were employed: (1) standard traffic signal; (2) countdown-separated signal; and (3) countdown-overlaid signal. The countdownseparated and countdown-overlaid signals were designed to inform drivers of the remaining time of a green light before tuning to an amber light. Reaction times (sec) and satisfaction scores (7-point scale) for the two signals with a countdown indicator were compared with those for the standard traffic signal. Results: Reaction times of the countdown-separated (0.49 sec) and countdownoverlaid (0.43 sec) signals were significantly shorter than that of the standard signal (0.67 sec). Satisfaction scores of the countdown-separated (5.3 point) and countdownoverlaid (5.6 point) signals were greater than that of the standard signal (3.8 point). Lastly, the countdown-overlaid signal showed better performance than the countdownseparated signal, but their differences in reaction time (0.06 sec) and satisfaction score (0.3 point) were small. Conclusion: Traffic signals with a countdown indicator can improve drivers" reaction time and satisfaction score than the standard traffic signal. Application: Traffic signals with a countdown indicator will be useful for reducing the length of dilemma zone at intersections, by allowing drivers to predict the remaining time of a green light.

음향반향제거기에서 암묵신호분리를 이용한 동시통화처리

이행우,Lee, Haengwoo 디지털산업정보학회 2016 디지털산업정보학회논문지 Vol.12 No.1

This paper is on an acoustic echo canceller solving the double-talk problem by using the blind signal separation technology. The acoustic echo canceller may be deteriorated or diverged during the double-talk period. So we use the blind signal separation to detect the double talking by separating the near-end speech signal from the mixed microphone signal. The blind signal separation extracts the near-end signal from dual microphones by the iterative computations using the 2nd order statistical character in the closed reverberation environment. By this method, the acoustic echo canceller operates irrespective of the double-talking. We verified performances of the proposed acoustic echo canceller in the computer simulations. The results show that the acoustic echo canceller with this algorithm detects the double-talk periods well, and then operates stably without diverging of the coefficients after ending the double-talking. The merits are in the simplicity and stability.

Hough 변환을 이용한 암묵신호분리방법

이행우 (사)디지털산업정보학회 2014 디지털산업정보학회논문지 Vol.10 No.3

This paper is on the blind signal separation(BSS) method by the geometric method. To separate the signal sources, we use Hough transform and BSS. Hough transform is a geometric method which let us know the local informations of the signal. We find the orientations of signals by Hough transform and know the number of signal sources. When the number of sensors is more than the number of sources. the BSS algorithm can separate the mixtures well in the time domain. This algorithm has a good performance in converging fast. We had checked up the quality of the algorithm after separating the mixed signals. The results of simulations show that this BSS method has the abnormal waveforms due to unconverging coefficients in the beginning, and stably has the separated waveforms which almost equal to the sources in the most period.

A Probabilistic Short-length Linear Predictability Approach to Blind Source Separation

Mahdi Khosravy,Mohammad Reza Alsharif,Katsumi Yamashita 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

A merit function based on short length linear predictability of signal in an objective probabilistic algorithm is defined and used for blind source separation (BSS) of linear mixtures of signals. In BSS literatures, it has been conjectured that linear mixture of statistically independent source signals will result in a set of signals which each of them has less predictability than (or equal to) that of any of component source signals. We have used this property to extract source signals by finding an un-mixing matrix that maximizes the proposed merit function of predictability for each recovered signal. This method which is called Probabilistic Short-length Linear Predictability BSS (PSLP-BSS), its performance has been driven with many tests performed with mixtures of different kinds (speech, audio, image, constructed mathematical signals like saw tooth and sinusoidal). In all cases, correlation between each of source signals and each of extracted signals shows near-perfect performance of the method. The proposed BSS doesnt require any assumption regarding the probability density function of source signals. It has been demonstrated that PSLP-BSS can separate signal mixtures in which each mixture is a linear combination of source signals with gaussian, super-gaussian and sub-gaussian probability density functions. However, the method is adapted to temporal structure of recovered signals. Since, the un-mixing matrix that is concluded by proposed merit function can be obtained as the solution to a generalized eigenvalue routine, signals can be extracted simultaneously using the fast eigen value.

암묵신호분리를 이용한 스테레오 음향반향제거기

이행우 (사)디지털산업정보학회 2012 디지털산업정보학회논문지 Vol.8 No.3

This paper is on a stereo acoustic echo canceller with the blind signal separation. The convergence speed of the stereo acoustic echo canceller is deteriorated due to mixing two residual signals in the update signal of each echo canceller. To solve this problem, we are to use the blind signal separation(BSS) method separating the mixed signals. The blind signal separation method can extracts the source signals by means of the iterative computations with two input signals. We had verified performances of the proposed acoustic echo canceller for stereo through simulations. The results of simulations show that the acoustic echo canceller for stereo using this algorithm operates stably without divergence in the normal state. And, when the speech signals were inputted, this echo canceller achieved about 3dB higher ERLE in the case of using the BSS algorithm than the case of not using the BSS algorithm. But this echo canceller didn’t get good performances in the case of inputting the white noises as stereo signals.

음향반향제거기에서 기하학적 개념의 BSS를 이용한 동시통화 제어

이행우(Haeng-Woo Lee) 한국전자통신학회 2017 한국전자통신학회 논문지 Vol.12 No.3

본 논문은 기하학적 개념에 기반한 암묵신호분리를 이용하여 동시통화문제를 제어하는 음향반향제거기에 관한 것이다. 음향반향제거기는 동시통화 구간에서 성능이 저하되거나 발산하게 된다. 따라서 혼합된 마이크입력신호로부터 근단화자신호를 분리해서 동시통화상태를 검출하기 위하여 암묵신호분리기술을 이용한다. 암묵신호분리는 미지의 입력신호들로부터 기하학적 개념에 기반하여 변형과 회전의 두 단계를 거쳐 근단화자신호를 추정해낸다. 컴퓨터 시뮬레이션을 통하여 이 음향반향제거기의 성능을 검증하였다. 동시통화 구간에서는 반향제거필터의 계수가 발산하는 것을 방지하기 위하여 계수 갱신작업을 중지하도록 하였다. 시뮬레이션 결과, 이 방법을 사용한 음향반향제거기는 암묵신호분리의 빠른 수렴속도로 인해 동시통화의 유무에 상관없이 안전하게 동작함을 확인하였다. This paper describes an acoustic echo canceller with double-talk using BSS(: Blind Signal Separation) based on the geometric concept. The acoustic echo canceller may be deteriorated or diverged during the double-talk period. So we use the blind signal separation to detect the double talking by separating the near-end speech signal from the mixed microphone signal. In the closed reverberation environment, the blind signal separation extracts the near-end signal from unknown signals with the transformation and rotation based on the geometric concept. By this method, the acoustic echo canceller operates irrespective of double-talking. We verified performances of the proposed acoustic echo canceller by computer simulations. The results show that the acoustic echo canceller with this algorithm detects the double-talk periods thoroughly, and operates stably in the normal state without diverging of coefficients after ending the double-talking.

스테레오 음향반향제거기의 BSS 후처리방법

이행우 (사)디지털산업정보학회 2014 디지털산업정보학회논문지 Vol.10 No.1

This paper is on a stereo acoustic echo canceller with the blind signal separation for postprocessing. The convergence speed of the stereo acoustic echo canceller is deteriorated due tomixing two residual signals which are update signals of each echo canceller. To solve thisproblem, we are to use the blind signal separation(BSS) method separating the mixed signalsafter the echo cancellers. The blind signal separation method can extracts the source signalsby means of the iterative computations with two input signals. We had verifiedperformances of the proposed acoustic echo canceller for stereo through simulations. Theresults of simulations show that the acoustic echo canceller for stereo using this algorithmoperates stably without divergence in the normal state. And, when the speech signals wereinputted, this echo canceller achieved about 2dB higher ERLE with the BSS post processingmethod than without this method. This stereo echo canceller showed the best performance inthe case of inputting the real voice signal.

Effective Separation Method for Single-Channel Time-Frequency Overlapped Signals Based on Improved Empirical Wavelet Transform

( Zhipeng Liu ),( Lichun Li ),( Huiqi Li ),( Chang Liu ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.5

To improve the separation performance of time-frequency overlapped radar and communication signals from a single channel, this paper proposes an effective separation method based on an improved empirical wavelet transform (EWT) that introduces a fast boundary detection mechanism. The fast boundary detection mechanism can be regarded as a process of searching, difference optimization, and continuity detection of the important local minima in the Fourier spectrum that enables determination of the sub-band boundary and thus allows multiple signal components to be distinguished. An orthogonal empirical wavelet filter bank that was designed for signal adaptive reconstruction is then used to separate the input time-frequency overlapped signals. The experimental results show that if two source components are completely overlapped within the time domain and the spectrum overlap ratio is less than 60%, the average separation performance is improved by approximately 32.3% when compared with the classic EWT; the proposed method also improves the suitability for multiple frequency shift keying (MFSK) and reduces the algorithm complexity.

Convolutive 암묵신호분리방법에 기반한 음향반향 제거

이행우(Haeng Woo Lee) 한국전자통신학회 2018 한국전자통신학회 논문지 Vol.13 No.5

본 논문은 암묵신호분리방법을 이용한 음향반향 제거에 관한 것이다. 이 방법은 동시통화 중에도 반향제거 성능이 저하되지 않는다. 폐쇄된 반향환경에서 음향신호의 혼합모델은 다채널이기 때문에 convolutive 암묵신호분리방법을 적용하며 신호분리를 위해 분리계수를 직접 계산하지 않고 역방향 모델을 이용하여 혼합계수를 산출하는 방식으로 이루어진다. 계수 갱신은 2차 통계적 성질을 기반으로 반복적인 계산에 의해 수행됨으로서 근단화자 신호를 추정해낸다. 제안한 암묵신호분리의 성능을 검증하기 위해 많은 시뮬레이션을 수행하였다. 시뮬레이션 결과, 이 방법을 사용한 음향반향제거기는 동시통화의 유무에 상관없이 안전하게 동작하고, 일반적인 적응 FIR 필터구조에 비해 PESQ가 0.6점 향상되는 것으로 나타났다. This paper deals with acoustic echo cancellation using blind signal separation method. This method does not degrade the echo cancellation performance even during double-talk. In the closed echo environment, the mixing model of acoustic signals is multi-channel, so the convolutive blind signal separation method is applied and the mixing coefficients are calculated by using the feedback model without directly calculating the separation coefficients for signal separation. The coefficient update is performed by iterative calculations based on the second-order statistical properties, thus estimates the near-end speech. A number of simulations have been performed to verify the performance of the proposed blind signal separation method. The simulation results show that the acoustic echo canceller using this method operates safely regardless of the presence of double-talk, and the PESQ is improved by 0.6 point compared with the general adaptive FIR filter structure.

원격참조 (RR: Remote Reference) 기법과 신호잡음분리 (SNS: Signal Noise Separation) 기술을 이용한 용인 관측소의 지자기 전달함수 분석

양준모(Junmo Yang),이덕기(Duk-Kee Lee),권병두(Byung-Doo Kwon),류용규(Yong-Gyu Ryu),윤용훈() 대한자원환경지질학회 2005 자원환경지질 Vol.38 No.2

RR (Remote Reference) 과 SNS (Signal Noise Separation) 기법을 도입하여 용인과 이천에서 측정된 지자기 전달함수를 분석하였다. RR 기법은 측정 사이트와 동시에 기록되는 원격참조 자료를 사용하여 자기장의 비상관 잡음 (un-correlated noise) 을 제거하는 기법으로서 전달함수의 편향을 최소화한다. 한편 SNS 기법은 원격참조 자료가 잡음이 거의 없다는 가정을 바탕으로 신호에 의한 전달함수와 상관잡음(correlated noise) 에 의한 전달함수를 분리하는 기법으로서, 측정 사이트에 상관잡음이 지배적인 경우에도 신호에 의해 전달함수를 성공적으로 추정할 수 있다. 본 연구에서는 자료의 질이 양호하다고 판단되는 이천을 원격참조 자료로 사용하여, 용인에서의 전달함수를 분석하였다. RR 기법을 적용한 결과, 단일 로버스트 추정(Single robust estimation) 에서 나타났던 편향이 감소되었고, 주파수에 따른 전달함수의 연결성도 향상되었다. 잡음원에 대한 보다 정량적인 분석을 위해 SNS 기법을 적용한 결과, 주기 100 초이하에서 용인의 서쪽에 존재하는 잡음원의 존재를 확인하였다. 이러한 잡음원은 용인의 서쪽을 지나가는 국철, 고속 철도 등의 철도 시스템에 의한 것으로 생각된다. For an unbiased TF (Tansfer Function) estimations we investigate geomagnetic TF derived from ICHEON and YONGIN sites, employing RR (Remote Reference) and SNS (Signal Noise Separation) techniques. The RR technique, which requires synchronized field variations recorded at a clean remote site, is a reliable method to minimize the bias of TF by uncorrelated noises in magnetic channels. Meanwhile, SNS technique based on the assumption of noise-free remote data can improve the signal-noise level by separating signal TF and noise TF, which is successfully applied to the environments with strong correlated noises. In this study, TF at YONGIN is analyzed using geomagnetic data from ICHEON site as a remote reference, which seem to have somewhat better data quality. The application of RR technique reduces the bias of TF, which appears in single site robust estimation, and makes curves in the amplitude and phase of TF more smooth as frequency. Futhermore, in order to investigate noise source quantitatively, SNS technique is applied. The results of SNS suggest that dominant noise source seems to be located at western region of YONGIN. This noise source is considered to originate from railway system such as KTX and national subway, which passes through the west regions of YONGIN.