• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.3
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• pp.286-293
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• 1983

This study measures polar compressive thickness strain and radius of curvature of the bulge through Moire' method in bulge test. Hill's and Alexander's bulge theories, instability conditions derived by Swift's, Hill's, Alexander's and wang's theories, are also investigated, compared with Moire' experimental results. In order to review and compare with Hill's and Alexander's bulge theories, the relationships between radius of curvature of the bulge and polar height, between polar compressive thickness strain and polar height, are used. Mild steel, soft copper and commercial pure aluminum are used in Moire' experiment. According to this study, Hill's and Alexander's bulge theories, instability conditions derived by Swift's, Hill's, Alexander's and Wang's theories are agreement to Moire' experiment results.

• Journal of Welding and Joining
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• v.22 no.3
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• pp.45-49
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• 2004

Generally, it is used the compensation spring to compensate the inaccuracy of screen image induced by thermal deformation in CRT monitor. Its mechanism is hi-metallic system made of heterogeneous metals and these springs are bonded by laser welding. But laser welding induces a non-uniform temperature distribution, and residual stress is yielded locally by these temperature deviation. Therefore, this study measures the curvature constant to assess functions of the compensation spring of shadow mask with respect to increment temperature and estimates the effect of residual stress on the performance of tri-metal used to compensation spring.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.7
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• pp.167-174
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• 1998

This paper presents an unoccluded cylindrical object pose measurement using a slit beam laser in which a robot recognizes all of the unoccluded objects from the top of jumbled objects, and picks them up one by one. The elliptical equation parameters of a projected curve edge on a slice are calculated using LSM. The coefficients of standard elliptical equation are compared with these parameters to estimate the object pose. The hamming distances between the estimated coordinates and the calculated ones are extracted as measures to evaluate a local constraint and a smoothing surface curvature. The edges between slices are linked using error function based on the edge types and the hamming distances. The linked edges on slices are compared with the model object's length to recognize the unoccluded object. This proposed method may provide a solution to the automation of part handling in manufacturing environments such as punch press operation or part assembly.

• Journal of Institute of Control, Robotics and Systems
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• v.22 no.8
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• pp.597-602
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• 2016

In image guided surgery, a patient registration process is a critical process for the successful operation, which is required to use pre-operative images such as CT and MRI during operation. Though several patient registration methods have been studied, we concentrate on one method that utilizes 3D surface measurement data in this paper. First, a hand-held 3D surface measurement device measures the surface of the patient, and secondly this data is matched with CT or MRI data using optimization algorithms. However, generally used ICP algorithm is very slow without a proper initial location and also suffers from local minimum problem. Usually, this problem is solved by manually providing the proper initial location before performing ICP. But, it has a disadvantage that an experience user has to perform the method and also takes a long time. In this paper, we propose a method that can accurately find the proper initial location automatically. The proposed method finds the proper initial location for ICP by converting 3D data to 2D curvature images and performing image matching. Curvature features are robust to the rotation, translation, and even some deformation. Also, the proposed method is faster than traditional methods because it performs 2D image matching instead of 3D point cloud matching.

• Journal of the HCI Society of Korea
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• v.10 no.2
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• pp.13-19
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• 2015

Display technology has recently made enormous progress. In particular, display companies are competing each other to develop flexible display. Curved display, as a precursor of flexible display, are now used for smart phones and TVs. Curved monitors have been just introduced in the market, and are used for office work or entertainment. The aim of the current study was to investigate whether the curvature of a 42" multi-monitor affects postural control when it is used for entertainment purpose. The current study used two curvature levels (flat and 600mm). Ten college students [mean(SD) age = 20.9 (1.5)] with at least 20/25 visual acuity, and without color blindness and musculoskeletal disorders participated in this study. In a typical VDT environment, each participant played a car racing video game using a steering wheel and pedals for 30 minutes at each curvature level. During the video game, a pressure mat on the seat pan measured the participant's COP (Center of Pressure), and from which four measures (Mean Velocity, Median Power Frequency, Root-Mean-Square Distance, and 95% Confidence Ellipse Area) were derived. A larger AP (Anterior-Posterior) RMS distance was observed in the flat condition, indicating more forward-backward upper body movements. It can be partly due to more variability in visual distance across display, and hence longer ocular accommodation time in the case of the flat display. In addition, a different level of presence or attention between two curvature conditions can lead to such a difference. Any potential effect of such a behavioral change by display curvature on musculoskeletal disorders should be further investigated.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.32.6-32
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• 2002

The damage localization of the structural system using the natural frequency measurement only is proposed. The existing methods use the changes of mode shape, strain mode shape or curvature mode shape before and after the damage occurrence as these shapes carry the geometric information of the structure. Basically, the change of natural frequencies of the structure can be used as the indicator of the damage occurrence but not as the indicator of the damage location as the natural frequency changes does not carry the geometric information of the structure. In this research, the feedback scope method that measures the natural frequency changes of the structure with and without the feedback Ioo...

• The Journal of Korean Physical Therapy
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• v.34 no.5
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• pp.272-277
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• 2022

Purpose: This study compared the subjective and objective sleep quality between subjects with and without thoracic hyper-kyphosis. Methods: Forty participants were divided into a hyper-kyphosis (n=17) and normal group (n=17) by thoracic spinal angle measurement. The subjective sleep quality was measured using PSQI, a self-report, and objective sleep quality was measured using an actigraphy that measures time according to sleep patterns. Results: The PSQI scores of subjects with thoracic hyper-kyphosis were significantly higher than those with normal thoracic curvature (p=0.013). The total sleep time and real sleep time were less in subjects with hyper-kyphosis than in normal subjects (p=0.006; p=0.029). The light sleep time was less in subjects with excessive spondylolisthesis than in normal subjects (p=0.010). Light sleep time was less in those with hyper-kyphosis, but deep sleep time was similar to the subjects with a normal thoracic curvature (p=0.003; p=0.140). Conclusion: Subjects with thoracic hyper-kyphosis had a decrease in subjective sleep quality, such as sleep discomfort, and objective sleep quality, such as a decrease in sleep time compared to normal subjects.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.3
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• pp.192-197
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• 2013

In this study, it is investigated the relationship between sitting discomfort and major design variables of lumber support, such as prominence, height and width through volunteer tests. Korean $50^{th}$ percentile males and American $50^{th}$ percentile males are recruited among 36 to 45 years old peoples who have driving experiences and have no back pain during the past 12 months. Subject ratings are asked by changing design variables randomly. Body pressure and lumber position changes are also measured as object measures. And correlation among subject ratings, object measures and three design variables are analyzed using statistical analysis. As a result, it is revealed that prominence is the most dominant factor that correlates to the discomfort strongly for both-Koreans and Americans and contribution of other two variables are very low.

• Journal of the Earthquake Engineering Society of Korea
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• v.26 no.6
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• pp.255-265
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• 2022

In order to determine fragility curves, the limit state of piers for each damage level is suggested in this paper based on the previous test results in Korea, including our test results. In previous studies, the quantitative measures for damage levels of piers have been represented by curvature ductility, lateral drift ratio, or displacement ductility. These measures are transformed to lateral drift ratios of piers for consistency, and the transformed values are compared and verified with our push-over test results for flexural RC piers with a circular cross-section. The test specimens are categorized concerning the number of lap-splices in the plastic hinge region and whether seismic design codes are satisfied or not. Based on the collected test results in Korea, including ours, the lateral drift ratio for each pier damage level is suggested.

• International Journal of Highway Engineering
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• v.4 no.4 s.14
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• pp.41-52
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• 2002

This study dealt with analysis of size effect of testing apparatus for Kim test which measures rut resistance characteristics of asphalt mixture under static loading. Two columns in different diameter with each column having different radios of round cut (Curvature) at the bottom were used for testing asphalt mixture. Deformation load ($P_{max}$) and deformation strength ($K_D$) were found to have relatively high correlation with rut depth and dynamic stability of asphalt concrete. Diameter of specimen was not a significant factor in this test. From the statistical correlation analysis with rutting properties, the radius of curvature and diameter of loading column were found to be important factor affecting the results of the test. Among the radios (r) of curvatures, r=0.5cm and 1.0cm showed much higher correlation than the column without curvature, and r=1.0cm being better between the two. The column with diameter of 4cm showed better correlation than diameter of 3cm. Therefore, the column of 4cm diameter with r=1.0cm was found to be the best among various apparatus sizes. Prediction models for rut depth and dynamic stability were developed for each aggregate mixture based on Kim test variables using SAS STEPWISE procedure. Therefore, if this test method is validated through further study, Kim test can be used for selecting asphalt mixture with the highest resistance against permanent deformation.