• 한국항공우주학회지
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• 제34권5호
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• pp.93-100
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• 2006

본 논문에서는 레이더와 원격측정시스템으로부터 수신되는 다중센서자료를 모사하는 시뮬레이터 설계와 이들 자료를 융합하기 위한 알고리듬 개발에 대하여 소개한다. 설계된 데이터 시뮬레이터는 실제 센서 시스템으로부터 얻게 되는 시간의 비동기, 통신지연, 다중 갱신주기들을 갖는 모의센서 자료를 생성하며 실제적인 센서 모델을 이용하여 측정 잡음을 생성한다. 융합알고리듬은 센서 바이어스 상태를 고려한 PVA모델을 기초로 21차 분산형 칼만 필터로 설계되었고, 센서의 이상이나 정상적이 아닌 측정치를 검출하기 위한 로직도 포함되었다. 설계된 알고리듬을 시뮬레이터에서 생성한 모의 자료 및 실제 자료를 적용하여 검증하였다.

• The Journal of the Acoustical Society of Korea
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• 제21권2E호
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• pp.71-80
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• 2002

This paper suggests the Cardioid beamforming algorithm of the doublet sensors employing DIFAR (directional frequency analysis and recording) sensor signals in the frequency domain. The algorithm enables target bearing estimation using the signals from directional sensors. The algorithm verifies its applicability by successfully estimating bearings of a target projecting ten narrow-band signals in shallow water. The estimated bearings agree very well with those from GPS (global positioning system) data. Assuming the bearings from GPS data to be real values, the estimation errors are analyzed statistically. The histogram of estimation errors in each frequency have Gaussian shape, the mean and standard deviation dropping in the ranges -1.1°∼ 6.7°and 13.3∼43.6°, respectively. Estimation errors are caused by SNR (signal to noise ratio) degradation due to propagation loss between the source and receiver, daily fluctuating geo-magnetic fields, and non-stationary background noises. If multiple DIFAR systems are employed, in addition to bearing, range information could be estimated and finally localization or tracking of a target is possible.

• 조명전기설비학회논문지
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• 제20권5호
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• pp.99-106
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• 2006

능동 머플러는 스피커를 이용하여 배기 소음과 크기는 같으나 위상이 반대인 상쇄 소음을 발생시켜 소음을 제거하기 때문에 엔진 속도의 변화나 음향특성의 변화에 빠르게 적응할 수 있다. 본 논문에서는 안정도를 강화한 다중채널 적응 IIR 필터를 제안하고 이를 이용한 능동형 머플러를 구현하였다. 일반적으로 적응 IIR 필터는 차수에 비해 성능이 좋으나 안정성에 문제가 있기 때문에 능동소음제어 시스템의 작동 초기에 안정도를 개선하는 전처리 과정을 수행하였다. 자동차 머플러를 수학적으로 모델링하고 가솔린과 디젤 자동차의 엔진소음을 측정, 분석하였다. 컴퓨터 시뮬레이션을 수행하여 안정도를 강화한 다중채널 IIR 필터를 이용한 능동소음제어의 유용성을 확인하였고 자동차 배기관을 모형화한 머플러를 제작하여 실험을 수행하였다.

• 한국통신학회논문지
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• 제28권7A호
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• pp.520-528
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• 2003

본 논문에서는 다자간 화상회의 시스템에서 합성 입체 음향을 재현하는 방법과 음향반향제거 방법을 제안한다. 합성 입체 음향은 HRTF(head related transfer function)을 이용하여 구현하고 반향제거를 위하여 주변잡음에 대하여 강건한 적응 알고리즘을 제안한다. 제안하는 알고리즘은 SMAP(set-membership affine projection)을 변형한 것으로 적응필터의 계수를 갱신할 때 입력신호와 추정오차신호의 상호상관을 입력신호의 자기상관 행렬과 투영 차수를 곱한 추정오차신호 전력의 합으로 정규화한다. 제안하는 적응알고리즘은 SMAP 알고리즘과 비교하여 투영차수와 주변잡음에 대하여 강건한 특성을 갖는다. 컴퓨터 시뮬레이션을 통해 제안하는 합성 입체음향 반향제거기의 성능이 효과적으로 반향을 제거할 수 있음을 보인다.

• 대한기계학회논문집A
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• 제30권6호
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• pp.728-733
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• 2006

The reduction of the Vehicle interior noise has been the main interest of NVH engineers. The driver's perception on the vehicle noise is affected largely by psychoacoustic characteristic of the noise as well as the SPL. In particular, the HVAC sound among the vehicle interior noise has been reflected sensitively in the side of psychology. In previous study, we have developed to verify identification of source for the vehicle HVAC system through multiple-dimensional spectral analysis. Also we carried out objective assessments on the vehicle HVAC noises and subjective assessments have been already performed with 30 subjects. In this study, the linear regression models were obtained for the subjective evaluation and the sound quality metrics. The regression procedure also allows you to produce diagnostic statistics to evaluate the regression estimates including appropriation and accuracy. Appropriation of regression model is necessary to $R^2$ value and F-value. And testing for regression model is necessary to independence, homoscedesticity and normality. Also we selected optimum layout of damping material using Taguchi method. As a result of application, sound quality is improved more quietly, powerfully, even though costly, and smoothly.

• Current Optics and Photonics
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• 제3권6호
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• pp.531-540
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• 2019

Spectral Amplitude Coding Optical Code Division Multiple Access (SAC OCDMA) is an advanced technique in asynchronous environments. This paper proposes design and implementation of a novel quantum logic gate (QLG) code, with code construction algorithm generated without following any code mapping procedures for SAC system. The proposed code has a unitary matrices property with maximum overlap of one chip for various clients and no overlaps in spectra for the rest of the subscribers. Results indicate that a single algorithm produces the same length increment for codes with weight greater than two and follows the same signal to noise ratio (SNR) and bit error rate (BER) calculations for a higher number of users. This paper further examines the performance of a QLG code based SAC-OCDMA system with NAND and direct detection techniques. BER analysis was carried out for the proposed code and results were compared with existing MDW, RD and GMP codes. We demonstrate that the QLG code based system performs better in terms of cardinality, which is followed by improved BER. Numerical analysis reveals that for error free transmission (10^-9), the suggested code supports approximately 170 users with code weight 4. Our results also conclude that the proposed code provides improvement in the code construction, cross-correlation and minimization of noises.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1264-1286
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• 2018

In this paper, a novel background prior-based salient object detection framework is proposed to deal with images those are more complicated. We take the superpixels located in four borders into consideration and exploit a mechanism based on image boundary information to remove the foreground noises, which are used to form the background prior. Afterward, an initial foreground prior is obtained by selecting superpixels that are the most dissimilar to the background prior. To determine the regions of foreground and background based on the prior of them, a threshold is needed in this process. According to a fixed threshold, the remaining superpixels are iteratively assigned based on their proximity to the foreground or background prior. As the threshold changes, different foreground priors generate multiple different partitions that are assigned a likelihood of being foreground. Last, all segments are combined into a saliency map based on the idea of similarity voting. Experiments on five benchmark databases demonstrate the proposed method performs well when it compares with the state-of-the-art methods in terms of accuracy and robustness.

• 정보처리학회논문지C
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• 제9C권4호
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• pp.459-466
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• 2002

본 논문에서는 웨이블렛 서브밴드 필터링기법을 이용하여 다중의사 결정기법에 기반을 둔 잡음에 강인한 화자식별 알고리즘을 제안한다. 제안된 방법은 잡음이 첨가된 음성신호를 웨이블렛 서브밴드 필터뱅크를 이용하여 각 주파수 대역별로 신호를 분리한 후 개별적인 대역별로 인식 알고리즘을 수행하기 때문에 어떤 서브밴드에서의 노이즈 영향이 상대적으로 적으므로 대역제약된 형태로 주어지는 일반적인 주변잡음이 있는 환경하에서 우수한 성능을 보일 수 있도록 시스템을 구성하였다. 제안된 알고리즘은 화자인식 기법으로 널리 쓰이고 있는 벡터양자화 알고리즘만을 적용한 경우에 비해 15∼60%의 향상된 인식률을 보였다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권3호
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• pp.322-326
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• 2004

This paper describes a new iris recognition method based on a shift-invariant wavelet sub-images. For the feature representation, we first preprocess an iris image for the compensation of the variation of the iris and for the easy implementation of the wavelet transform. Then, we decompose the preprocessed iris image into multiple subband images using a shift-invariant wavelet transform. For feature representation, we select a set of subband images, which have rich information for the classification of various iris patterns and robust to noises. In order to reduce the size of the feature vector, we quantize. each pixel of subband images using the Lloyd-Max quantization method Each feature element is represented by one of quantization levels, and a set of these feature element is the feature vector. When the quantization is very coarse, the quantized level does not have much information about the image pixel value. Therefore, we define a new similarity measure based on mutual information between two features. With this similarity measure, the size of the feature vector can be reduced without much degradation of performance. Experimentally, we show that the proposed method produced superb performance in iris recognition.

• 한국군사과학기술학회지
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• 제5권2호
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• pp.169-184
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• 2002

In order to extract bearing information from the directional sensors of DIFAR(directional frequency analysis and recording) that is a kind of passive sonobuoy, the cardioid beamforming algorithm applicable to DIFAR system was studied in the frequency domain. the algorithm uses narrow-band signals propagated though the media from the acoustic sources such as ship machineries. The proposed algorithm is expected to give signal to noise ratio of 6dB when it uses the maximum response axis(MRA) among the Cardioid beams. The estimated bearings agree very well with those from GPS data. Assuming the bearings from GPS data to be real values, the estimation errors are analyzed statistically. The histogram of estimation errors in each frequency have Gaussian shape, the mean and standard deviation dropping in the ranges -1.1~$6.7^{\circ}$ and 13.3~$43.6^{\circ}$, respectively. Estimation errors are caused by SMR degradation due to propagation loss between the source and receiver, daily fluctuating geo-magnetic fields, and non-stationary background noises. If multiple DIFAR systems are employed, in addition to bearing, range information could be estimated and finally localization or tracking of a target is possible.