Hyeong-Seop Jeon

Displacement Measurement of Multi-point Using a Pattern Recognition from Video Signal

This paper proposes a way to measure the displacement of a multi-point by using a pattern recognition from video signal. Generally in measuring displacement, gab sensor, which is a displacement sensor, is used. However, it is difficult to measure displacement by using a common sensor in places where it is unsuitable to attach a sensor, such as high-temperature areas or radioactive places. In this kind of places, non-contact methods should be used to measure displacement and in this study, images of CCD camera were used. When multi-point is measure by using a pattern recognition, it is possible to measure displacement with a non-contact method. It is simple to install and multi-point displacement measuring device so that it is advantageous to solve problems of spatial constraints.

MULTI-POINT MEASUREMENT OF STRUCTURAL VIBRATION USING PATTERN RECOGNITION FROM CAMERA IMAGE

Modal testing requires measuring the vibration of many points, for which an accelerometer, a gab sensor and laser vibrometer are generally used. Conventional modal testing requires mounting of these sensors to all measurement points in order to acquire the signals. However, this can be disadvantageous because it requires considerable measurement time and effort when there are many measurement points. In this paper, we propose a method for modal testing using a camera image. A camera can measure the vibration of many points at the same time. However, this task requires that the measurement points be classified frame by frame. While it is possible to classify the measurement points one by one, this also requires much time. Therefore, we try to classify multiple points using pattern recognition. The feasibility of the proposed method is verified by a beam experiment. The experimental results demonstrate that we can obtain good results.

Measuring Structural Vibration from Video Signal Using Curve Fitting

Many studies for measuring vibration using image signal are suggested. These methods can measure vibration of multi-points simultaneously. However, it has the disadvantage that is very sensitive to an environment. If the measured environment is not good, image signals can be measured including much background noise. So, it is difficult to obtain accurate vibration from the measured image signals. Another problem is that camera imaging has a resolution limit. Because the resolution of the camera image is relatively much lower than that of a data acquisition system, accurate measuring vibration cannot be performed. In this paper, we proposed the enhanced technique for measuring vibration using camera signal. The key word of this paper is a curve fitting. The curve fitting can exactly detect the measurement line of interested object. So, we can measure the vibration in noisy environment. Also, it can overcome the resolution limit.

A Technique for Measuring Vibration Displacement Using Camera Image

Vibration measurements using image processing have been studied by many researchers as it can remotely measure vibration displacements at multiple points simultaneously. It is difficult, however, to obtain accurate displacement from the measured image signals because the resolution of image data is dependent on camera performance and normally lower than that of vibration transducer directly measured. This paper suggests the enhanced technique for vibration displacement measurement by applying the expected value of edge probability distribution to the varying pixel points in the image. The method can both increase the resolution limit of camera image and decrease the measurement errors. The working performance of the proposed technique is verified applying to the vibration measurement of a rotating machine.

Steam Leak Detection by Using Image Signal

Steam leakage is one of the major issues for the structural fracture of pipes of nuclear power plants. Therefore a method to inspect a large area of piping systems quickly and accurately is needed. In this paper, we proposed the method for the detecting steam leakage by using image signal processing. Our basic idea come from heat shimmer which shine with a soft light that looks as if it shakes slightly. To test the performance of this technique, experiments have been performed for simple heat source and steam generator. Results show that the proposed technique is quite powerful in the steam leak detection.

A Technique for Vibration Measurement and Roundness Assessment of Rotating-axis using Camera Image

ABSTRACT Vibration measurement of rotating shafts by installing sensors such as accelerometers or displace-ment sensors is costly and dangerous in some cases. As an alternative method, vibration measure-ment using camera images has been researched because sensor installation is not needed and dis-placement of a rotating shaft can be directly evaluated. This paper also suggests the enhanced techni-que applicable to the measurement of vibration of a large-scale rotating shaft. The concurrent meth-ods based on camera images use marks, which are hardly applicable to rotating shafts. The proposed method measures vibration without any marks by evaluating shape errors. The working principle of the method is described and verified by a series of experiments. * Nomenclature D : 축 중심기준 촬영거리 D pixel : 픽셀 단위 지름 F ( S 1 ): 관심영역 A 의 픽셀단위 변위값 F ( S 2 ): 관심영역 B 의 픽셀단위 변위값 P 1 : 관심영역 A 의 기준좌표 P 2 : 관심영역 B 의 기준좌표 P size : 단위 픽셀당 실제 사이즈 (mm) R : 축 반지름 S ( i , j ): 측정대상 그레이 영상 f ( A ): 상부 측정 신호 f (

Parameter Studies for Measuring Vibration by Using Camera

Accelerometer and laser vibrometers are widely used to measure vibration of structures like a building or piping. Recently, the research measuring vibration by using camera image is introduced. This method can measure multi-points simultaneously. Also, it is possible to measure in the long distance. When we measure the vibration using a camera, the parameter analysis is needed. Therefore, this paper took the experiment for the camera lens selection. An error by the camera images characteristic was theoretically analyzed and we verified through an experiment. And the accuracy of the method measuring the vibration displacement by using the camera images was analyzed.

Steam Leak Detection Method in a Pipeline Using Histogram Analysis

Abstract Leak detection in a pipeline usually involves acoustic emission sensors such as contact type sensors. These contact type sensors pose difficulties for installation and cannot operate in areas having high temperature and radiation. Therefore, recently, many researchers have studied the leak detection phenomenon by using a camera. Leak detection by using a camera has the advantages of long distance monitoring and wide area surveillance. However, the conventional leak detection method by using difference images often mistakes the vibration of a structure for a leak. In this paper, we propose a method for steam leakage detection by using the moving average of difference images and histogram analysis. The proposed method can separate the leakage and the vibration of a structure. The working performance of the proposed method is verified by comparing with experimental results. Keywords: Image Processing, Steam Leak Detection, Vibration of Structure, Moving Average, Difference Image, Histogram Analysis[Received: August 11, 2015, Revised: October 12, 2015, Accepted: October 21, 2015] *세안기술(주), **충남대학교 정보통신공학과, ✝Corresponding Author: Department of Information Communications Engineering, Chungnam National University, Daejeon 305-764, Korea (E-mail: jwpark@cnu.ac.kr)

Enhancement of Displacement Resolution of Vibration Data Measured by using Camera Images

Vibration measurement using image processing is a fully non-contact measurement method and has many application fields. The resolution of vibration data measured by image processing depends on the camera performance and is lower than that measured by accelerometers. This work discusses the method to increase resolution of vibration signal measured by image processing based on the image mosaic technique with a high-power lens. The working principle of resolution enhancement was explained theoretically and verified by several experiments. It was shown that the proposed method can measure vibrations of relatively large scale structures with increased resolutions.

Correction of Error due to Camera Vibrating During Detecting Steam Leakage by Using Image

Steam leakage is one of the major issues for the structural fracture of pipes of nuclear power plants. Therefore a method to inspect a large area of piping systems quickly and accurately is needed. Recently, the research detecting the steam leakage by using camera image is introduced. However, this method has a disadvantage. If a camera oscillates, it cannot detect a steam leakage exactly. In this paper, the technique that reduces the error due to a camera shaking is proposed. To verify the proposed method, we have performed the experiments for the oil leakage experiments. The results show that the technique can calibrate the error due to camera shaking.