• 제목/요약/키워드: Effective detection distance

검색결과 107건 처리시간 0.028초

시간지연 추정을 통한 누수위치 식별 연구 (Time Delay Estimation for the Identification of Leak Location)

  • 이영섭;윤동진;김치엽
    • 한국소음진동공학회:학술대회논문집
    • /
    • 한국소음진동공학회 2004년도 추계학술대회논문집
    • /
    • pp.327-332
    • /
    • 2004
  • Leak noise is a good source to identify the exact location of a leak point of underground water pipelines. Water leak generates broadband noise from a leak location and can be propagated to both directions of water pipes. This sound propagation due to leak in water pipelines is not a non-dispersive wave any more because of the surrounding pipes and soil. However, the necessity of long-range detection of this leak location makes to identify low-frequency acoustic waves rather than high frequency ones. Acoustic wave propagation coupled with surrounding boundaries including cast iron pipes is theoretically analyzed and the wave velocity was confirmed with experiment. The leak locations were identified both by the acoustic emission (AE) method and the cross-correlation method. In a short-range distance, both the AE method and cross-correlation method are effective to detect leak position. However, the detection for a long-range distance required a lower frequency range accelerometers only because higher frequency waves were attenuated very quickly with the increase of propagation paths. Two algorithms for the cross-correlation function were suggested, and a long-range detection has been achieved at real underground water pipelines longer than loom.

  • PDF

Variable Selection and Outlier Detection for Automated K-means Clustering

  • Kim, Sung-Soo
    • Communications for Statistical Applications and Methods
    • /
    • 제22권1호
    • /
    • pp.55-67
    • /
    • 2015
  • An important problem in cluster analysis is the selection of variables that define cluster structure that also eliminate noisy variables that mask cluster structure; in addition, outlier detection is a fundamental task for cluster analysis. Here we provide an automated K-means clustering process combined with variable selection and outlier identification. The Automated K-means clustering procedure consists of three processes: (i) automatically calculating the cluster number and initial cluster center whenever a new variable is added, (ii) identifying outliers for each cluster depending on used variables, (iii) selecting variables defining cluster structure in a forward manner. To select variables, we applied VS-KM (variable-selection heuristic for K-means clustering) procedure (Brusco and Cradit, 2001). To identify outliers, we used a hybrid approach combining a clustering based approach and distance based approach. Simulation results indicate that the proposed automated K-means clustering procedure is effective to select variables and identify outliers. The implemented R program can be obtained at http://www.knou.ac.kr/~sskim/SVOKmeans.r.

Realization for Moving Object Tracking System in Two Dimensional Plane using Stereo Line CCD

  • Kim, Young-Bin;Ryu, Kwang-Ryol;Sun, Min-Gui;Sclabassi, Robert
    • 한국정보통신학회:학술대회논문집
    • /
    • 한국해양정보통신학회 2008년도 추계종합학술대회 B
    • /
    • pp.157-160
    • /
    • 2008
  • A realization for moving object detecting and tracking system in two dimensional plane using stereo line CCDs and lighting source is presented in this paper. Instead of processing camera images directly, two line CCD sensor and input line image is used to measure two dimensional distance by comparing the brightness on line CCDs. The algorithms are used the moving object tracking and coordinate converting method. To ensure the effective detection of moving path, a detection algorithm to evaluate the reliability of each measured distance is developed. The realized system results are that the performance of moving object recognizing shows 5mm resolution and mean error is 1.89%, and enables to track a moving path of object per 100ms period.

  • PDF

교량케이블 영상기반 손상탐지 (A Vision-based Damage Detection for Bridge Cables)

  • ;이종재
    • 한국방재학회:학술대회논문집
    • /
    • 한국방재학회 2011년도 정기 학술발표대회
    • /
    • pp.39-39
    • /
    • 2011
  • This study presents an effective vision-based system for cable bridge damage detection. In theory, cable bridges need to be inspected the outer as well as the inner part. Starting from August 2010, a new research project supported by Korea Ministry of Land, Transportation Maritime Affairs(MLTM) was initiated focusing on the damage detection of cable system. In this study, only the surface damage detection algorithm based on a vision-based system will be focused on, an overview of the vision-based cable damage detection is given in Fig. 1. Basically, the algorithm combines the image enhancement technique with principal component analysis(PCA) to detect damage on cable surfaces. In more detail, the input image from a camera is processed with image enhancement technique to improve image quality, and then it is projected into PCA sub-space. Finally, the Mahalanobis square distance is used for pattern recognition. The algorithm was verified through laboratory tests on three types of cable surface. The algorithm gave very good results, and the next step of this study is to implement the algorithm for real cable bridges.

  • PDF

가보 필터를 이용한 이미지 위조 검출 기법 (Image Forgery Detection Using Gabor Filter)

  • ;이경현
    • 한국정보처리학회:학술대회논문집
    • /
    • 한국정보처리학회 2014년도 추계학술발표대회
    • /
    • pp.520-522
    • /
    • 2014
  • Due to the availability of easy-to-use and powerful image editing tools, the authentication of digital images cannot be taken for granted and it gives rise to non-intrusive forgery detection problem because all imaging devices do not embed watermark. Forgery detection plays an important role in this case. In this paper, an effective framework for passive-blind method for copy-move image forgery detection is proposed, based on Gabor filter which is robust to illumination, rotation invariant, robust to scale. For the detection, the suspicious image is selected and Gabor wavelet is applied from whole scale space and whole direction space. We will extract the mean and the standard deviation as the texture features and feature vectors. Finally, a distance is calculated between two textures feature vectors to determine the forgery, and the decision will be made based on that result.

Mitigation of Adverse Effects of Malicious Users on Cooperative Spectrum Sensing by Using Hausdorff Distance in Cognitive Radio Networks

  • Khan, Muhammad Sajjad;Koo, Insoo
    • Journal of information and communication convergence engineering
    • /
    • 제13권2호
    • /
    • pp.74-80
    • /
    • 2015
  • In cognitive radios, spectrum sensing plays an important role in accurately detecting the presence or absence of a licensed user. However, the intervention of malicious users (MUs) degrades the performance of spectrum sensing. Such users manipulate the local results and send falsified data to the data fusion center; this process is called spectrum sensing data falsification (SSDF). Thus, MUs degrade the spectrum sensing performance and increase uncertainty issues. In this paper, we propose a method based on the Hausdorff distance and a similarity measure matrix to measure the difference between the normal user evidence and the malicious user evidence. In addition, we use the Dempster-Shafer theory to combine the sets of evidence from each normal user evidence. We compare the proposed method with the k-means and Jaccard distance methods for malicious user detection. Simulation results show that the proposed method is effective against an SSDF attack.

다중 정상 하에서 단일 클래스 분류기법을 이용한 이상치 탐지 : TFT-LCD 공정 사례 (A Novelty Detection Algorithm for Multiple Normal Classes : Application to TFT-LCD Processes)

  • 주태우;김성범
    • 대한산업공학회지
    • /
    • 제39권2호
    • /
    • pp.82-89
    • /
    • 2013
  • Novelty detection (ND) is an effective technique that can be used to determine whether a future observation is normal or not. In the present study we propose a novelty detection algorithm that can handle a situation where the distributions of target (normal) observations are inhomogeneous. A simulation study and a real case with the TFT-LCD process demonstrated the effectiveness and usefulness of the proposed algorithm.

다양한 컬러 공간에 따른 영상 내 화염 검출 성능 연구 (A Study on Fire Flame Detection Performance in the Images of Various Color Spaces)

  • 최병수;김정대;도용태
    • 한국멀티미디어학회:학술대회논문집
    • /
    • 한국멀티미디어학회 2012년도 춘계학술발표대회논문집
    • /
    • pp.284-286
    • /
    • 2012
  • There has been increasing attention about the prevention and counter-measure of disasters. Particularly, for the case of fire disaster, early detection reduces the damage caused by fire significantly and effective detection method is important. Since most existing detectors need to be located at a close distance to fire, analyzing camera images to find fire becomes active research topic. In this paper, we analyze the color characteristics of fire images in various color spaces and report the experimental detection results. The best result is 77.8% success rate in YIQ space.

  • PDF

Passive and Active Detection of Conducting Nanoparticles by Nanogaps

  • Lee, Cho Yeon;Park, Jimin;Park, Jong Mo;Kang, Aeyeon;Yun, Wan Soo
    • 한국진공학회:학술대회논문집
    • /
    • 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
    • /
    • pp.268.1-268.1
    • /
    • 2013
  • Immobilization of conducting nanoparticles on a nanogap comprising two electrodes spaced at a distance comparable to the particle size can be used as a simple and sensitive method of detecting the particles. In this work, we have examined the performance of the nanogap devices in the measurement of metallic nanoparticles, particularly gold nanoparticles (Au NPs). Detection of pM-level Au NPs in an aqueous suspension was quite straightforward irrespective of the existence of non-conducting materials. Speed of detection or the time necessary for the completion of the measurement, however, was strongly dependent upon the immobilization process. Active trapping process was found to be much more efficient and also effective in the detection of nanoparticles than its passive counterpart.

  • PDF

실시간 이미지 처리 방법을 이용한 개선된 차선 인식 경로 추종 알고리즘 개발 (Development of an Improved Geometric Path Tracking Algorithm with Real Time Image Processing Methods)

  • 서은빈;이승기;여호영;신관준;최경호;임용섭
    • 자동차안전학회지
    • /
    • 제13권2호
    • /
    • pp.35-41
    • /
    • 2021
  • In this study, improved path tracking control algorithm based on pure pursuit algorithm is newly proposed by using improved lane detection algorithm through real time post-processing with interpolation methodology. Since the original pure pursuit works well only at speeds below 20 km/h, the look-ahead distance is implemented as a sigmoid function to work well at an average speed of 45 km/h to improve tracking performance. In addition, a smoothing filter was added to reduce the steering angle vibration of the original algorithm, and the stability of the steering angle was improved. The post-processing algorithm presented has implemented more robust lane recognition system using real-time pre/post processing method with deep learning and estimated interpolation. Real time processing is more cost-effective than the method using lots of computing resources and building abundant datasets for improving the performance of deep learning networks. Therefore, this paper also presents improved lane detection performance by using the final results with naive computer vision codes and pre/post processing. Firstly, the pre-processing was newly designed for real-time processing and robust recognition performance of augmentation. Secondly, the post-processing was designed to detect lanes by receiving the segmentation results based on the estimated interpolation in consideration of the properties of the continuous lanes. Consequently, experimental results by utilizing driving guidance line information from processing parts show that the improved lane detection algorithm is effective to minimize the lateral offset error in the diverse maneuvering roads.