• Journal of Computing Science and Engineering
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• 제11권3호
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• pp.79-91
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• 2017

In this paper, the abdominal-deformation measurement scheme is conducted on a shape-flexible mannequin using the DIC technique in a stereo-vision system. Firstly, during the integer-pixel displacement search, a novel fractal dimension based on an adaptive-ellipse subset area is developed to track an integer pixel between the reference and deformed images. Secondly, at the subpixel registration, a new mutual-learning adaptive particle swarm optimization (MLADPSO) algorithm is employed to locate the subpixel precisely. Dynamic adjustments of the particle flight velocities that are according to the deformation extent of each interest point are utilized for enhancing the accuracy of the subpixel registration. A test is performed on the abdominal-deformation measurement of the shape-flexible mannequin. The experiment results indicate that under the guarantee of its measurement accuracy without the cause of any loss, the time-consumption of the proposed scheme is significantly more efficient than that of the conventional method, particularly in the case of a large number of interest points.

• 소성∙가공
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• 제9권4호
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• pp.404-412
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• 2000

It is desirable to use the square grid analysis with the aid of the stereo vision and image processing techniques in order to automatically measure the surface-strain distribution over a stamped part. But this method has some inherent problems such as the difficulty in enhancement of bad images, the measurement error due to the digital image resolution and the limit of the area that can be measured at a time. Therefore, it is still hard to measure the strain distribution over the entire surface of a medium-or large-sized stamped part even by using an automated strain measurement system. In this study, several methods which enable to solve these problems considerably without losing accuracy and precision In measurement are suggested. The superposition of images that have different high-lightened or damaged part from each other gives much enhanced image. A new algorithm for constructing of the element connectivity from the line-thinned image helps recognize up to 1,000 elements. And the geometry assembling algorithm including the global error minimization makes it possible to measure a large specimen with reliability and efficiency.

• 한국정밀공학회지
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• 제15권10호
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• pp.96-102
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• 1998

In this study, the theory and application of phase-shifting shadow moire topography is focused on the non-contact measurement of object surfaces for practical use in the field of production engineering. Shadow moire topography has been studied during last few decades in the area of the optical physics, and now its mathmatical theory has been established. Generally, in case of the classical shadow moire topography, the sensitivity is a few tenths of millimeter in best cases. Here we tried the application of phase-shifting method to the conventional shadow moire topography. But the reference grating and the deformed grating are mutually dependent because it is impossible to obtain uniform phase shifts on the whole Held. Therefore it is difficult to use a phase-shifting method in shadow moire topography. However, it was shown that constant phase-shifting was able to be measured by moving both the grating and light source. Finally we obtained a better result by using this procedure and applied the phase-shifting shadow moire to three dimensional object measurement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.303-305
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• 2014

This paper is concerned with the vibration measurement of cable by image processing technique. The measurement system consists of a CCD camera and zoom lens. The image data can be transferred to PC via USB or IEEE1394 port. In this study, a Matlab program was made to process the acquired image data. After acquiring an image data for each frame, this data is binarized for tracing cable vibrations. Then the area occupied by the cable is marked by 1 and the background is covered by 0. In this way, we can calculate the displacement of the cable. Experimental results show that the tracing of cable displacements is possible and natural frequencies and mode shapes can be computed. The accuracy of the image processing system for vibration measurement depends on the maximum frame rate of the CCD camera. The use of a high-speed camera enables us to compute more higher modes. The laboratory experiments guarantee the vibration measurement of real transmission lines.

• 한방재활의학과학회지
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• 제15권2호
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• pp.183-191
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• 2005

Objectives : The 5th lumbar - 1st sacrum facet joint is unstable area from an anatomical viewpoint, so that it is clinically major causes of low back pain. The purpose of this study is to assess the difference of the Van Akkerveeken measurement and intervertebral disc angle, Ferguson angle betwoon the 5th lumbar - 1st sacrum facet syndrome patients and sample group patients.Methods : Van Akkerveeken measurement, intervertebral disc angle and Ferguson angle were measured in 30 patients who had 5th lumbar - 1st sacrum facet syndrome and 31 sample group patients.Results :1. Van Akkerveeken measurement of 5th lumbar - 1st sacrum facet syndrome patients is statistically larger that of than sample group patients.2. Intervertebral disc angle of the 5th lumbar - 1st sacrum facet syndrome patients is statistically larger that of than sample group patients.3. Ferguson angle is the 5th lumbar - 1st sacrum facet syndrome patients is statistically larger than that of sample group patients.Conclusions : These results suggest that Van Akkerveeken measurement and intervertebral disc angle is able to be used for diagnosis of facet syndrome.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.482-483
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• 2007

For measurement of dielectric constants, the commercial parallel plate electrodes system with guard-ring electrode have been widely used up to now. The capacitance derived from the parallel plate electrodes capacitor with guard-ring electrode is calculated by the equation of ($C={\epsilon}\;{\cdot}\;\frac{area\;of\;electrod}{distance\;between\;electrodes}$). Therefore, in parallel plate electrode capacitor, the diameter of the guarded electrode, the gap size between guarded electrode and guard ring, and distance between two active electrode should be measured precisely to calculate dielectric constants from the measured capacitance. Consequently their mechanical measurement uncertainties are directly contributed. Especially the air-gap between the electrodes and dielectric specimen at the system must be existed and the measurement error derived from the air-gap is impossible to evaluate as measurement uncertainties. In this study, we analyze the uncertainty of the commercial dielectric constant test cell using 3 kinds CRMs.

• 대한기계학회논문집A
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• 제20권4호
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• pp.1233-1240
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• 1996

Conventional measurement methods using ultrasonic wave or x-ray, eddy current for non-destructive testing(NDT) in nuclear power plants and other industrial plants have been utilized as the method of contact with objects to be inspected. For this reason these methods require relatively much time and inspection area is limited by the location of probe or film. But holograpic interferometry which is a non-contact optical measurement method using a coherent light source has an advantage that quantative measurement can be performed at a time. In this paper a new method using realtime holographic interfreometry and image processing for detecting internal flaws of pressure vessels is presented.

• 한국안전학회지
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• 제34권4호
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• pp.15-21
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• 2019

In order to secure the safety of various machinery, it is very important to develop a technique for accurately and quickly measuring the cracks generated in the mechanical equipment and evaluating the mechanical characteristics. The evaluation of the mechanical properties is accompanied by an appropriate strain measurement according to the material and crack occurrence of the target structure. Especially, when micro cracks are generated, the evaluation method is very important. Digital image correlation is an optical full field displacement measuring method which is using currently with speckles in the interested area. However the evaluation method and conditions of image distributions have to be considered carefully to measure the crack occurrence because the images of the speckle patterns affect the quality of displacement results. In this study, the speckle pattern density is characterized to improve the accuracy of the measurement method. And also the micro crack initiation is detected by the measured displacement in the adopted speckle pattern distribution. It is shown that the proposed method is useful to determine the density pattern distribution for the accurate measurement and crack detection.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.4160-4173
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• 2019

Borescopes facilitate the inspection of areas inside machines and systems that are not directly accessible for visual inspection. They offer real-time, up-close access to confined and hard-to-access spaces without having to dismantle or destructure the object under inspection. Borescopes are ideal instruments for routine maintenance, quality inspection and monitoring of systems and structures. The main application being fault or defect detection, it is useful to have measuring capability to quantify object dimensions in a target area. High-end borescopes use multi-optic solutions to provide measurement information of viewed objects. Multi-optic solutions can provide accurate measurements at the expense of structural complexity and cost increase. Measuring functionality is often unavailable in low-end, single camera borescopes. In this paper, a single camera measurement solution that enables the size estimation of viewed objects is proposed. The proposed solution computes and overlays a scaled grid of known spacing value over the screen view, enabling the human inspector to estimate the size of the objects in view. The proposed method provides a simple means of measurement that is applicable to low-end borescopes with no built-in measurement capability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권11호
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• pp.3875-3891
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• 2021

In this study, a Velostat pressure sensor was manufactured to develop a plantar pressure measurement system and a C#-based application was developed to monitor and collect plantar pressure data in real time. In order to evaluate the characteristics of the proposed plantar pressure measurement system, the accuracy of plantar pressure index and personal classification was verified by comparing with MatScan, a commercial plantar pressure measurement system. As a result, the output characteristics according to the weight of the Velostat pressure sensor were evaluated and a trend line with the reliability of r² = 0.98 was detected. The Root Mean Square Error(RMSE) of the weighted area was 11.315 cm², the RMSE of the x coordinate of Center of Pressure(CoP_x) was 1.036 cm and the RMSE of the y coordinate of Center of Pressure(CoP_y) was 0.936 cm. Finally, inaccuracy of personal classification, the proposed system was 99.47% and MatScan was 96.86%. Based on the advantage of being simple to implement and capable of manufacturing at low cost, it is considered that it can be applied to various fields of measuring vital signs such as sitting posture and breathing in addition to the plantar pressure measurement system.