• Journal of Institute of Control, Robotics and Systems
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• v.8 no.1
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• pp.37-45
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• 2002

A method of measuring the length of defects on the wall and restructuring the defect image is proposed based on the estimation algorithm of a camera orientation, which uses the declination angle of a laser slit beam. The estimation algorithm of the horizontally inclined angle of CCD camera adopts a 3-dimensional coordinate transformation of the image plane where both the laser beam and the original image of the defects exist. The estimation equation is obtained by using the information of the beam projected on the wall and the parameters of this equation are experimentally obtained. With this algorithm, the original image of the defect can be reconstructed as an image normal to the wall. From the result of a series of experiments, the measuring accuracy of the defect is measured within 0.5% error bound of real defect size under 30 degree of the horizontally inclined angle. The proposed algorithm provides the method of reconstructing the image taken at any arbitrary horizontally inclined angle as the image normal as the wall and thus, it enables the accurate measurement of the defect lengths by using a single camera and a laser slit beam.

• Journal of Korean Foot and Ankle Society
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• v.16 no.1
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• pp.53-57
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• 2012

Purpose: To study computerized measurements of angular parameters on 100% and 150% resized digital radiography of hallux valgus deformity Materials and Methods: 30 digital radiography of standing foot anteroposterior view of hallux valgus patients were included. Two observers(A, B) independently measured hallux valgus angle (HVA), 1-2 intermetatarsal angle (IMA), and distal metatarsal articular angle (DMAA) in two times on both 100%-size and 150% magnified images respectively, using computerized measurement software tools. The results were interpreted with the statistical software program, Statistical Analysis System, version 9.2. Results: In repeated measurements of each observer, measurements on 150% magnified image showed no differences of all three parameters and with 100%-size image, there were differences of HVA (observer A) and 1-2 IMA (observer B) (p>0.05). When testing interobserver reliability, both observers showed differences in measurement of HVA and DMAA (p<0.05), but no differences in measurement of 1-2 IMA in both images. Within the 95% confidence interval, limits of error of measurements between two observers on HVA, IMA and DMAA were $2.7^{\circ}$ $1.4^{\circ}$ and $5.0^{\circ}$ respectively in 100%-size images, and $2.6^{\circ}$, $1.6^{\circ}$ and $4.7^{\circ}$ respectively in 150% magnified images. Conclusion: In computerized measurements for angular parameters of hallux valgus with digital radiography, 150% magnified images showed intraobserver reliability. Both 100% and 150% magnified images failed to show interobserver reliability. Measurement of 1-2 IMA in both 100% and 150% images showed less interobserver error.

• Journal of Korean Neurosurgical Society
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• v.39 no.4
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• pp.256-259
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• 2006

Objective : Having a reliable and reproducible measurement technique to measure the sagittal contour in vertebral fractures is paramount to clinical decision making. This study is designed to determine the most reliable measurement technique in osteoporotic vertebral compression fracture. Methods : Fifteen lateral radiographs of thoracic and lumbar fractures were selected and measured on two separate occasions by three spine surgeons using six different measurement techniques [Centroid, Harrison Posterior Tangent Methods and 4 different types of modified Cobb method]. The radiograph quality was assessed and the center beam location was determined. Statistical analysis including ANOVA for repeated measures was carried out using the SAS software [v 8.0]. Results : The inter and intraobserver variance of the Cobb method 4 and Harrison posterior tangent method were significantly lower than the other four methods. The intraobserver correlation coefficients were the most consistent using the Cobb method 4 [0.982]. which was followed by the Harrison posterior tangent [0.953] and Cobb methods 1 [0.874]. The intraobserver agreement [% of repeated measures within 5 degrees of the original measurement] ranged from 42% to 98% for each technique for all three observers, with the Cobb method 4 showing the best agreement [97.8%] followed by the Harrison posterior tangent method [937%]. Conclusion : The Cobb method-4 and Harrison posterior tangent methods, when applied to measuring the kyphosis, are reliable and have a similar small error range. The Cobb method 4 shows the best overall reliability. However, the centroid method and Cobb method using a fractured endplate do not produce an accurate result due to inter and intraobserver differences in determining the baseline.

• Journal of the Korean Solar Energy Society
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• v.37 no.6
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• pp.25-37
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• 2017

A study on factors influencing measurement error of Ground-based LiDAR(Light Detection And Ranging) system was conducted in Kimnyeong wind turbine test site on Jeju Island. Three properties of wind including inclined angle, turbulence intensity and power law exponent were taken into account as factors influencing the measurement error of Ground-based LiDAR. In order to calculate LiDAR measurements error, 2.5-month wind speed data collected from LiDAR (WindCube v2) were compared with concurrent data from the anemometer on a nearby 120m-high meteorological mast. In addition, data filtering was performed and its filtering criteria was based on the findings at previous researches. As a result, at 100m above ground level, absolute LiDAR error rate with absolute inclined angle showed 4.58~13.40% and 0.77 of the coefficients of determination, $R^2$. That with turbulence intensity showed 3.58~23.94% and 0.93 of $R^2$ while that with power law exponent showed 4.71~9.53% and 0.41 of $R^2$. Therefore, it was confirmed that the LiDAR measurement error was highly affected by inclined angle and turbulence intensity, while that did not much depend on power law exponent.

• The Research Journal of the Costume Culture
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• v.14 no.4
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• pp.609-624
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• 2006

The purpose of this study is to give the guideline to the pattern designing by supplying various images of the transformed shape of tailored collar with the location and angle of gorge line and laying measurement of the tailored collar while designing the tailored collar. The results of this study are as follows : Images of the sample at the case of 1cm of laying measurement looks 'urban', 'light', 'sharp', 'young', 'fashionable' and 'narrow' than that at the case of 7cm. When the laying measurement increases, the image of the sample looks more 'classical' and 'boorish'. The image of the sample 'light', 'sensuous' and 'young' at the case of sample of which laying measurements of the collar was 3cm. Second, at the case of sample whose laying measurements of the collar was 5cm, it was shown that the low location of gorge line made the image of the sample 'soft' and 'short'. On the other hand the image of the sample looked 'hard', 'keen' and 'long' by the high location of gorge line. Third, at the case of sample of which laying measurements of the collar was 7cm, low location of gorge line made the image of the sample look short. However, normal location of gorge line made the image of the sample looked 'fashionable'. The images of the samples of which laying measurements of the collar were 3cm, 5cm and 7cm, respectively, had changed with the angle of gorge line. First, the high angle of gorge line made the image of the sample 'rigid' and 'keen' at the case of sample of which laying measurements of the collar was 3cm. The high angle of gorge line made the image of the sample looked 'boorish' and 'singular'.

• PNF and Movement
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• v.22 no.1
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• pp.1-11
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• 2024

Purpose: The prevalent use of mobile devices may contribute to musculoskeletal disorders, such as forward head posture (FHP), among users. The measurement of the craniovertebral angle (CVA) using photographic images is frequently employed in assessing FHP. Although manual CVA measurement using photographic images is reliable in clinical settings, computer programs or mobile applications to support tele-physical therapy are not yet fully developed. Therefore, in the current study, we propose an automatic method for extracting CVA from photographic images of FHP subjects to facilitate tele-physical therapy. Methods: To develop the automatic CVA measuring computer program, photographic images were obtained from 10 FHP participants. The location information obtained from the markers attached to the tragus and the spinous process of the seventh cervical vertebra were used as coordinates. Using these coordinates, straight line 1 was generated by connecting the seventh spinous process of the cervical vertebra and the tragus, while straight line 2 was drawn parallel to the coordinate obtained from the seventh spinous process of the cervical vertebra. The arc tangent function was used to calculate the angle between the two straight lines. The automatic CVA measurement computer program utilizing photographic images was developed using MATLAB (ver. 2016b). Results: The results showed that the automatic CVA measurement computer program demonstrated stable repeatability and high accuracy. Conclusion: The proposed approach was able to automatically estimate the CVA using photographic images. The developed computer program can potentially be used for easier and more reliable clinical assessment of FHP.

• The KSFM Journal of Fluid Machinery
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• v.13 no.4
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• pp.18-24
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• 2010

For testing large-capacity pumps, the accurate flow rate measurement is needed in the test loop. As a measuring method of flow rate, venturi tube is recommended due to its low pressure loss. However, upstream disturbance of loop component such as a valve has an effect upon the accuracy of flow rate measurement. For controlling flow rate in case of high flow rate and large-scale piping system, a butterfly-type valve is generally used due to its compactness. However, a butterfly valve disturbs downstream flow by generating turbulence, cavities, or abrupt pressure change. In this study, the effect of downstream disturbance of butterfly valve on the flow rate measurement using a venturi tube is investigated. Test loop consists of circulation pump, reservoir, butterfly valve, venturi tube, and reference flow meter. The test is conducted with regard to a different valve opening angle of butterfly valve. According to the valve opening angle, the uncertainty of flow rate measurement is investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.175-183
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• 2021

This paper studies measurement of sonic boom created by supersonic flight and its arrival angle estimation techniques. Since sonic boom propagates as an impulsive noise and includes infrasound frequency, we propose measurement instrumentation acquiring sonic boom signature without distortion. And we suggest the methodology for an arrival angle estimation with its performance analysis in accordance with sensor array configurations. The performance of our estimator is verified by comparing theoretical performance bound with statistics of its Monte-Carlo simulation results. Furthermore, we presents the analysis of the sonic boom measurement from real flight tests. This work provides an intuitive concept for sensor array configurations and measurement instrumentation.

• Communications of Mathematical Education
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• v.33 no.3
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• pp.295-317
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• 2019

Angle concept is widely used in all mathematics curriculums and is a basic concept in geometric domain. Since angle have a multifaceted and affect subsequent learning, it is necessary for students to understand various angle concepts. In this study, Singapore, U.K., Australia, and U.S. are selected as comparable countries to examine the angle-related contents and learning process that appear in the curriculum as a whole, and then look at the perspectives and the size aspects of angle in detail and give implications to the Korean curriculum based on them. According to the analysis, the four countries except Korea, supplement angle, complement angle, angles on a straight line, angles at a point, and finding angle were explicitly covered in the curriculum. And most countries gradually covered angle-related contents over several years, compared to Korea which intensively studied in a particular school year. In common, definition of angle was described as static, measurement of angle was described as dynamic. But in Korean curriculum, dynamic views on angles are described later and less compared to other countries, and range of angle size was narrower than in other countries'. From this comparison, this study suggest to discuss how to place and develop various contents of characteristics of angle in curriculum, address the angle using both static and dynamic perspectives, and introduce the angle size as the amount of rotation to learn the reflex angle, $180^{\circ}$, $360^{\circ}$ angle.

• Journal of Biosystems Engineering
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• v.35 no.4
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• pp.257-261
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• 2010

Surface energy is the principal factor of anti-condensation. High surface energy appears hydrophilic itself and low surface energy represents hydrophobic itself. The contact angle is widely being used for measurement of surface energy of materials, evaluation of coating performances, measurement of wettability, and so on. However, the existing contact angle measuring system is so expensive for purchasing and complicated, so it takes a lot of time and money to use. This study was conducted to develop the algorithm for evaluating hydrophilic performance through measuring the contact angle of water droplet automatically, and fabricate relatively simple measuring system using a low-cost monochrome camera and image processing. A constant amount of water was firstly allocated on a slide by a micropipette, and then the image of water droplet was captured by monochrome digital camera and sent to a computer. The image was binarized and then reduced noises by labeling. Finally, the contact angle of water droplet was computed by using three points (left, right, and top coordinates), simple linear mathematics, and trigonometric function. The experimental results demonstrated the accuracy and reproducibility of the developed system showing less deviations and deviation ratio.