• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.200-207
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• 2003

In this paper we present a new method of measuring the relative distance of two point objects in three-dimensional space by using phase-shifting digital holography. In our system the reference beam of a spherical wave is used instead of a plane wave. The system is computer simulated and built on an optical table for experiments. It is shown from computer simulations and experiments that the relative distance can be measured without the exact information on the reference beam used in the hologram record. It is shown from experiments that the relative distance between two point objects separated by 0.5 cm in the distance of about 300 cm from the CCD can be measured with an error less than 10％.

• Archives of Craniofacial Surgery
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• v.20 no.1
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• pp.31-36
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• 2019

Background: After closed reduction, patients are sometimes concerned that their external nasal shapes have changed. The aim of this study was to investigate and explain changes in nasal shape after surgery through objective photogrammetric anthropometry measurements taken through three-dimensional (3D) reformed computed tomography (CT) images. Methods: Our study included 100 Korean patients who underwent closed reduction of isolated nasal bone fracture from January 2016 to June 2017. Using the ruler tool in Adobe Photoshop CS3, we measured preoperative and postoperative nasal base heights, long nostril axis lengths, both nasal alar angles, and amount of nasal deviation through the 3D reformation of soft tissue via CT scans. We then compared the dimension of nose. Results: The amount of postoperative correction for nasal base height was 1.192 mm. The differences in nostril length between each side were found to be 0.333 mm preoperatively and 0.323 mm postoperatively. The differences in the nasal alar angle between each side was $1.382^{\circ}$ preoperatively and $1.043^{\circ}$ postoperatively. The amount of nasal deviation was found to be 5.248 mm preoperatively and 1.024 mm in postoperatively. Conclusion: After the reduction of nasal bone fractures, changes in nasal dimensions were noticeable in terms of nasal deviation but less significant in nasal tips, except for changes in nasal alar angles, which were notable.

• Journal of the Korea Fashion and Costume Design Association
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• v.17 no.4
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• pp.55-66
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• 2015

The objective of this study is to propose a method by which movement fitness can be evaluated using a three-dimensional virtual garment simulation program. To this end, five types of jean pants for men were evaluated on the program by setting the avatars to make particular movements to examine the level of pressure on each body part. To verify whether the clothing pressure measurement produces valid and reliable results, virtual garment simulation program was utilized. The results indicated that there were significant differences in the levels of pressure on body parts depending on the type of test garment and motion. In addition, the clothing pressure measurement results were in line with the appearance evaluation results suggested by a previous study. Based on this set of results, the nomological validity of the clothing pressure measurement program used in this study was verified. Moreover, we employed an appearance evaluation along with the clothing pressure measurement to verify the reliability of the program; there was a high correlation between clothing pressure measurements and appearance evaluation measurements, indicating that measuring clothing pressures may well compensate for the limitations of appearance evaluation. We expect the results of this study to make valuable contributions in facilitating the digitalization of the fashion industry. Furthermore, this study also is significant in that it has suggested 3D virtual fitting programs as a solution to the long-criticized problem related to the evaluation of movement fitness in existing virtual garment simulation programs.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.5
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• pp.881-891
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• 2021

This study proposes a simple drape measurement method for the 3D virtualization of garments. The proposed method uses angles or disks of different diameters to evaluate the drape properties easily. We divided 710 fabrics into ten groups based on the drape coefficient, of which 49.6% had drape coefficients of 30 or less. The drape properties were measured to classify the groups into smaller clusters using the angle formed when the center of the fabric was fixed. Accordingly, three clusters were formed for 60° and 100° angles. A method was devised using ten disks of different diameters to classify the remaining two clusters, except the cluster containing only the D10 group (D1-D5 and D5-D9). Three criteria-grade match, a sum of deviation, and standardization of deviation-were used for the classifications. The discriminative ability between groups was high for D1-D5 with disks with 24.0 and 25.5 cm diameters. Furthermore, a disk with a diameter of 16.5 cm was effective for D5-D9. The three-dimensional drape shapes were unique for the ten groups, which can be utilized as fundamental data for 3D virtualization.

• Physical Therapy Korea
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• v.30 no.3
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• pp.174-183
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• 2023

Background: Office workers experience neck or back pain due to poor posture, such as flexed head and forward head posture, during long-term sedentary work. Posture correction is used to reduce pain caused by poor posture and ensures proper alignment of the body. Several assistive devices have been developed to assist in maintaining an ideal posture; however, there are limitations in practical use due to vast size, unproven long-term effects or inconsistency of maintaining posture alignment. We developed a headphone and necklace posture correction system (HANPCS) for posture correction using an inertial measurement unit (IMU) sensor that provides visual or auditory feedback. Objects: To demonstrate the test-retest reliability and concurrent validity of neck and upper trunk flexion measurements using a HANPCS, compared with a three-dimensional motion analysis system (3DMAS). Methods: Twenty-nine participants were included in this study. The HANPCS was applied to each participant. The angle for each action was measured simultaneously using the HANPCS and 3DMAS. The data were analyzed using the intraclass correlation coefficient (ICC) = [3,3] with 95% confidence intervals (CIs). Results: The angular measurements of the HANPCS for neck and upper trunk flexions showed high intra- (ICC = 0.954-0.971) and inter-day (ICC = 0.865-0.937) values, standard error of measurement (SEM) values (1.05°-2.04°), and minimal detectable change (MDC) values (2.92°-5.65°). Also, the angular measurements between the HANPCS and 3DMAS had excellent ICC values (> 0.90) for all sessions, which indicates high concurrent validity. Conclusion: Our study demonstrates that the HANPCS is as accurate in measuring angle as the gold standard, 3DMAS. Therefore, the HANPCS is reliable and valid because of its angular measurement reliability and validity.

• Imaging Science in Dentistry
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• v.36 no.2
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• pp.89-94
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• 2006

Purpose : To evaluate clinical usefulness of facial soft tissue thickness measurement using 3D computed tomographic images. Materials and Methods : One cadaver that had sound facial soft tissues was chosen for the study. The cadaver was scanned with a Helical CT under following scanning protocols about slice thickness and table speed; 3 mm and 3 mm/sec, 5 mm and 5 mm/sec, 7 mm and 7 mm/sec. The acquired data were reconstructed 1.5, 2.5, 3.5 mm reconstruction interval respectively and the images were transferred to a personal computer. Using a program developed to measure facial soft tissue thickness in 3D image, the facial soft tissue thickness was measured. After the ten-time repeation of the measurement for ten times, repeated measure analysis of variance (ANOVA) was adopted to compare and analyze the measurements using the three scanning protocols. Comparison according to the areas was analyzed by Mann-Whitney test. Results : There were no statistically significant intraobserver differences in the measurements of the facial soft tissue thickness using the three scanning protocols (p>0.05). There were no statistically significant differences between measurements in the 3 mm slice thickness and those in the 5 mm, 7 mm slice thickness (p>0.05). There were statistical differences in the 14 of the total 30 measured points in the 5 mm slice thickness and 22 in the 7 mm slice thickness. Conclusion : The facial soft tissue thickness measurement using 3D images of 7 mm slice thickness is acceptable clinically, but those of 5 mm slice thickness is recommended for the more accurate measurement.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.6
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• pp.561-568
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• 2011

The purpose of this study is to measure displacements that occurs on a surface and interior of slope model and the shape when the slope is destroyed at vibration experiment of the slope model using close range photogrammetry. The circle targets and sphere targets are installed on a chamber and a slope model, while the earthquake wave are applied in regular time interval. The close range photogrammetric images are acquired in each displacements step until the slope model is destroyed. Those photos are processed by image processing method and the center points of targets are automatically extracted. Furthermore, the three-dimensional coordinates of targets are calculated by image orientation and bundle adjustment processing. As a result, amount of displacement at each level is precisely measured and provided the basic information for assessing the slope stability using three-dimensional measurement of the target movement and slope destruction.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.4
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• pp.307-315
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• 1989

In this paper, we have analyzed the temperature variation trend of a slab on between the process of reheating furnace and the termination of roughing mill process during hot rolling process. 1) cooling by radiation and convection current in the air, 2) plastic deformation heat, 3) cooling by descaling water, 4) cooling by contact with rolling rolls and/or transmitting rolls. For the analysis, the factors have been adopted as the problems of the rolling process to be solved such that we have established an application technique in relation to the determination of boundary conditions on the slab surface. We have presented a procedure for an analysis of the cooling phenomenon treated as a problem of two-dimensional transient heat flow using finite difference equation and suggested techniques of implementing sequentialized rolling tasks in correlation with the procedure. From the result of simulation, it is shown that the difference between calculation value and measurement value is within the range of the industrial measurement error. Also, it is proved that the assumptions, conditions, and properties used in the computer simulation is appropriate by showing that the pattern of a drop in temperature at each rolling event is in accord with real circumstances.

• Physical Therapy Korea
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• v.24 no.2
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• pp.58-65
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• 2017

Background: Children with cerebral palsy (CP) have impaired postural control, but critically require the control of stability. Consequently, therapeutic interventions for enhancing postural control in children with CP have undergone extensive research. One intervention is sensorimotor training (SMT) using a Flexi-bar, but this has not previously been studied with respect to targeting trunk control in children with CP. Objects: This study was conducted to determine the effect of SMT using a Flexi-bar on postural balance and gait performance in children with CP. Methods: Three children with ambulatory spastic diplegia (SD) participated in the SMT program by using a Flexi-bar for forty minutes per day, three times a week, for six weeks. Outcome variables included the pediatric balance scale (PBS), trunk control movement scale (TCMS), 10 meter walking test (10MWT), and 3-dimensional movement coordination measurement. Results: The SMT provided no statistically significant improvement in PBS, TCMS, 10MWT, or 3-dimensional movement coordination measurement. However, positive changes were observed in individual outcomes, as balance and trunk control movement were improved. Conclusion: SMT using a Flexi-bar may be considered by clinicians as a potential intervention for increasing postural balance and performance in children with SD. Future studies are necessary to confirm the efficacy of Flexi-bar exercise in improving the functional activity of subjects with SD.

• Korean Journal of Remote Sensing
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• v.35 no.6_3
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• pp.1235-1249
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• 2019

Kilauea Volcano is one of the most active volcano in the world. In this study, we used the ALOS-2 PALSAR-2 satellite imagery to measure the surface deformation occurring near the summit of the Kilauea volcano from 2015 to 2017. In order to measure two-dimensional surface deformation, interferometric synthetic aperture radar (InSAR) and multiple aperture SAR interferometry (MAI) methods were performed using two interferometric pairs. To improve the precision of 2D measurement, we compared root-mean-squared deviation (RMSD) of the difference of measurement value as we change the effective antenna length and normalized squint value, which are factors that can affect the measurement performance of the MAI method. Through the compare, the values of the factors, which can measure deformation most precisely, were selected. After select optimal values of the factors, the RMSD values of the difference of the MAI measurement were decreased from 4.07 cm to 2.05 cm. In each interferograms, the maximum deformation in line-of-sight direction is -28.6 cm and -27.3 cm, respectively, and the maximum deformation in the along-track direction is 20.2 cm and 20.8 cm, in the opposite direction is -24.9 cm and -24.3 cm, respectively. After stacking the two interferograms, two-dimensional surface deformation mapping was performed, and a maximum surface deformation of approximately 30.4 cm was measured in the northwest direction. In addition, large deformation of more than 20 cm were measured in all directions. The measurement results show that the risk of eruption activity is increasing in Kilauea Volcano. The measurements of the surface deformation of Kilauea volcano from 2015 to 2017 are expected to be helpful for the study of the eruption activity of Kilauea volcano in the future.