• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1272-1275
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• 2002

Watermark detection plays a crucial role in multimedia copyright protection and has traditionally been tackled using correlation-based algorithms. However, correlation-based detection is not actually the best choice, as it does not utilize the distributional characteristics of the image being marked. Accordingly, an efficient watermark detection scheme for DWT coefficients is proposed as optimal for non-additive schemes. Based on the statistical decision theory, the proposed method is derived according to Bayes' decision theory, the Neyman-Pearson criterion, and the distribution of the DWT coefficients, thereby minimizing the missed detection probability subject to a given false alarm probability. The proposed method was tested in the context of robustness, and the results confirmed the superiority of the proposed technique over conventional correlation-based detection method.

• 제어로봇시스템학회논문지
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• 제7권4호
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• pp.304-308
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• 2001

The increase of video data makes the demand of efficient retrieval, storing, and browsing technologies necessary. In this paper, a video segmentation method (scene change detection method, or shot boundary detection method) for the development of such systems is proposed. For abrupt cut detection, inter-frame similarities are computed using luminance and edge histograms and a cut is declared when the similarities are under th predetermined threshold values. A gradual scene change detection is based on the similarities between the current frame and the previous shot boundary frame. A correlation method is used to obtain universal threshold values, which are applied to various video data. Experimental results show that propose method provides 90% precision and 98% recall rates for abrupt cut, and 59% precision and 79% recall rates for gradual change.

• Smart Structures and Systems
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• 제16권1호
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• pp.213-222
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• 2015

Early detection and precise location of leakage is of great importance for life-cycle maintenance and management of municipal pipeline system. In the past few years, acoustic emission (AE) techniques have demonstrated to be an excellent tool for on-line leakage detection. Regarding the multi-mode and frequency dispersion characteristics of AE signals propagating along a pipeline, the direct cross-correlation technique that assumes the constant AE propagation velocity does not perform well in practice for acoustic leak location. This paper presents an improved cross-correlation method based on wavelet transform, with due consideration of the frequency dispersion characteristics of AE wave and the contribution of different mode. Laboratory experiments conducted to simulate pipeline gas leakage and investigate the frequency spectrum signatures of AE leak signals. By comparing with the other methods for leak location identification, the feasibility and superiority of the proposed method are verified.

• 정보보호학회논문지
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• 제12권4호
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• pp.29-39
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• 2002

침입행위에 대한 비정상행위 탐지방법은 탐지에 대한 오판율이 높게 나타난다. 즉, 실제 침입이 아닌데 침입으로 판정하는 과탐지와 실제 침입인데 탐지하지 못하는 미탐지에 대한 오판율의 경우이다. 침입탐지의 민감도를 향상시키기 위하여 오용행위 및 비정상행위 탐지센서들 사이의 관련성을 이용하여 오판율을 감소하는 통합탐지의 방법을 연구하였다. 정상행위 및 비정상행위에 대해 하나의 탐지센서로부터의 결과가 다른 탐지센서에 의한 결과와 어떠한 관련성을 갖고 있는지의 반영비율을 오프라인에서 생성하고, 이를 실시간에 탐지된 결과에 적용하여 오판율을 감소하도록 하였다.

• 전기학회논문지
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• 제65권10호
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• pp.1774-1779
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• 2016

This paper proposes a portable cable fault detection system with automatic fault distinction and distance measurement using time-frequency correlation and reference signal elimination method and automatic fault classification algorithm in order to have more accurate fault determination and location detection than conventional time domain refelectometry (TDR) system despite increased signal attenuation due to the long distance to cable fault location. The performance of the developed system method was validated via an experiment in the test field constructed for the standardized performance test of power cable fault location equipments. The performance evaluation showed that accuracy of the developed system is less than 1.34%. Also, an error of automatic fault type and location by detection of phase and peak value through elimination of the reference signal and normalization of correlation coefficient and automatic fault classification algorithm not occurred.

• 로봇학회논문지
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• 제7권2호
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• pp.142-149
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• 2012

The camera has limitations of poor visibility in underwater environment due to the limited light source and medium noise of the environment. However, its usefulness in close range has been proved in many studies, especially for navigation. Thus, in this paper, vision-based object detection and tracking techniques using artificial objects for underwater robots have been studied. We employed template matching and mean shift algorithms for the object detection and tracking methods. Also, we propose the weighted correlation coefficient of adaptive threshold -based and color-region-aided approaches to enhance the object detection performance in various illumination conditions. The color information is incorporated into the template matched area and the features of the template are used to robustly calculate correlation coefficients. And the objects are recognized using multi-template matching approach. Finally, the water basin experiments have been conducted to demonstrate the performance of the proposed techniques using an underwater robot platform yShark made by KORDI.

• 한국컴퓨터정보학회논문지
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• 제9권4호
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• pp.157-165
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• 2004

본 논문에서는 현재 증가하고 있는 웹 서비스 공격을 정확하고 빠르게 탐지할 수 있고, 잘못된 공격탐지를 줄여줄 수 있는 웹서버 보안관리시스템을 제안한다. 이 시스템은 여러 단위보안모듈들의 결과를 실시간으로 수집하고 상호연관성 분석과정을 통해 탐지의 정확성을 향상시킨다. 단위보안모듈은 네트웍기반 침입탐지시스템 모듈, 파일무결성 검사 모듈, 시스템로그분석 모듈 그리고 웹로그분석 모듈로 구성되며, 그리고 각각의 단위보안모듈들의 결과에 연관성을 부여하여 실시간으로 분석하는 상호연관성 분석 모듈이 있다. 제안한 시스템은 공격탐지의 정확성 뿐 아니라 단위보안모듈의 추가 그리고 상호연관성 분석의 범위확장이 용이한 프레임워크를 제공한다. 그리고 제안한 시스템의 단위보안모듈 중 침입탐지시스템 모듈은 다중 쓰레드 기반으로 Snort를 재구성하여 보다 빠른 공격 탐지 시간을 갖는다. 처리량이 많은 단위보안모듈의 처리시간을 단축함으로서 웹서버 보안관리시스템 처리 성능을 향상시킬 수 있다.

• Nuclear Engineering and Technology
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• 제44권8호
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• pp.977-984
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• 2012

The cross-correlation technique has been widely used for leakage detection of buried pipes, and this technique can be successfully applied when the leakage signal has a high signal-to-noise ratio. In the case of a power plant, the measured leakage signals obtained from the sensors may contain background noise and mechanical noise generated by adjacent machinery. In such a case, the conventional method using the cross-correlation function may fail to estimate the leakage point. In order to enhance the leakage estimation capability of a buried pipe in a noisy environment, an improved cross-correlation technique is proposed. It uses a noise rejection technique in the frequency domain to effectively eliminate the tonal noise due to rotating machinery. Experiments were carried out to verify the validity of the proposed method. The results show that even in a tonal noisy environment, the proposed method can provide more reliable means for estimating the time delay of the leakage signals.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1689-1694
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• 2005

Face detection plays an important role in face recognition, video surveillance, and human computer interface. In this paper, we present a face detection system using eye detection with progressive thresholding from a digital camera. The face candidate is detected by using skin color segmentation in the YCbCr color space. The face candidates are verified by detecting the eyes that is located by iterative thresholding and correlation coefficients. Preprocessing includes histogram equalization, log transformation, and gray-scale morphology for the emphasized eyes image. The distance of the eye candidate points generated by the progressive increasing threshold value is employed to extract the facial region. The process of the face detection is repeated by using the increasing threshold value. Experimental results show that more enhanced face detection in real time.

• 한국정보과학회논문지:정보통신
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• 제30권4호
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• pp.504-512
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• 2003

본 논문에서는 디졸브 모델링 오차를 이용한 디졸브 검출 방법을 제안한다. 디졸브 모델링 오차는 디졸브 구간을 구성하는 두 장면 사이에 상관성이 없는 이상적인 디졸브 모델과 상관성이 존재하는 실제 디졸브 사이의 차이로 정의된다. 제안된 방법은 두 단계로 구성된다. 첫 번째 단계에서는 분산 곡선에서 나타나는 디졸브 구간의 특성인 아래로 볼록한 포물선을 검출하여 디졸브 후보 구간을 설정한다. 두 번째 단계에서는 선택된 후보 구간 자각에 대해 디졸브 모델링 오차를 정의하고 모델링 오차가 기준치와 비교한다. 기준치는 목표 모델링 오차로 각 후보 구간의 분산과 사용자에 의해 주어지는 목표 상관성에 대한 함수로 표현됨으로 제안된 기준치, 목표 모델링 오차는 각 후보 구간의 분산 변화에 적응적이다. 제안한 디졸브 검출 방법은 디졸브 구간을 구성하는 두 장면의 상관성을 고려하므로, 의미론적 디졸브 검출 방법이 될 수 있다. 제안된 방법을 다양한 동영상에 적용하여 성능을 평가하였다. 실험 결과 제안한 방법이 다양한 분산의 변화에도 불구하고 기존의 방법보다 정확하고 신뢰성 높은 디졸브 검출 결과를 나타내었다.