• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.1
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• pp.17-25
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• 2012

Purpose: Recently, a three dimensional approach to hard and soft tissues of the maxillofacial area has been widely used. This study was to evaluate the reproducibility and accuracy of a stereocamera compared to actual measurement methods using a digital caliper and digitizer. Methods: The stereoscopies of 7 head dummies with different sizes and shapes were obtained using a Di3D system (Dimensional Imaging, Glasgow, UK) after marking reference points on facial areas. From the obtained stereoscopy, 10 measurements representing the width, height and depth of each of the facial sections of the dummy were measured twice using a three dimensional reverse engineering software program (RapidForm$^{TM}$ 2006, Inus, Seoul, Korea). The x, y, and z coordinates of each of the three dimensional measurements were obtained and distances between two points were calculated. All procedures were repeated twice. The actual measurement method was performed twice, directly on dummies, using a digital caliper and values were compared with the previously determined values. Results: The results were as follows. In the ANOVA analysis, there were no significant statistical differences among the three measurement methods. In the Bonferroni analysis, with adjustments applied for multiple comparisons, there was no difference between actual measurement methods using a digitizer and a digital caliper. However, there was some difference between using a stereocamera and actual measurement methods using a digitizer and a digital caliper in values of $Ex_{Rt}-Ex_{Lt}$, $En_{Rt}-En_{Lt}$, $Ala_{Rt}-Ala_{Lt}$, $Ch_{Rt}-Ch_{Lt}$, G-Pg', $Ala_{Rt}$-Prn, $Ala_{Rt}$-Prn. The mean value for technical error in measurement (TEM) in Di3D (0.98 mm) was slightly higher than for a digital caliper (0.17 mm) and a digitizer (0.30 mm). In an intraclass correlation coefficient (ICC) there were no significant differences among the three measurement methods, but the Di3D system with the stereocamera showed relatively lower reproducibility compared to actual measurement methods using a digitizer and a digital caliper. Conclusion: These results indicate that some complementary measures may be needed to improve accuracy and reproducibility in the Di3D system with stereocamera.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1129-1138
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• 1999

[$Moir\acute{e}$] technique is now being extensively investigated as a fast non-contact means of three-dimensional profile measurement especially for reverse engineering. One problem with $moir\acute{e}$ technique is so called $2\pi$-ambiguity problem that limits the maximum step height difference between two neighboring sampling points to be less than half the equivalent wavelength of $moir\acute{e}$ fringes. In this investigation, a new two-wavelength scheme of projection $moir\acute{e}$ topography is proposed and tested to cope with the $2\pi$-ambiguity problem. Experimental results are discussed to assess the new method in measuring large objects with high step discontinuities.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.50-50
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• 2000

In this paper, a new measuring system is :proposed which can measure the fine 6-DOF displacement of rigid bodies. Its measurement principle is based on detection of laser beam reflected from a specially fabricated mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45$^{\circ}$ to its bottom surface. We call this mirror 3-facet mirror. The 3-facet mirror is mounted on the object whose 6-DOF displacement is to be measured. The measurement is operated by a laser-based optical system composed of a 3-facet mirror, a laser source, three position-sensitive detectors(PSD). In the sensor system, three PSDs are located at three corner points of a triangular formation, which is an equilateral triangular formation tying parallel to the reference plane. The sensitive areas of three PSDs are oriented toward the center point of the triangular formation. The object whose 6-DOF displacement is to be measured is situated at the center with the 3-facet mirror on its top surface. A laser beam is emitted from the laser source located at the upright position and vertically incident on the top of the 3-fatcet mirror. Since each reflective facet faces toward each PSD, the laser beam is reflected at the 3-facet mirror and splits into three sub-beams, each of which is reflected from the three facets and finally arrives at three PSDs, respectively. Since each PSD is a 2-dimensional sensor, we can acquire the information on the 6-DOF displacement of the 3-facet mirror. From this principle, we can get 6-DOF displacement of any object simply by mounting the 3-facet mirror on the object. In this paper, we model the relationship between the 6-DOF displacement of the object and the outputs of three PSDs. And, a series of simulations are performed to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects.

• Current Optics and Photonics
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• v.8 no.3
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• pp.246-258
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• 2024

In aerospace and energy engineering, the reconstruction of three-dimensional (3D) temperature distributions is crucial. Traditional methods like algebraic iterative reconstruction and filtered back-projection depend on voxel division for resolution. Our algorithm, blending deep learning with computer graphics rendering, converts 2D projections into light rays for uniform sampling, using a fully connected neural network to depict the 3D temperature field. Although effective in capturing internal details, it demands multiple cameras for varied angle projections, increasing cost and computational needs. We assess the impact of camera number on reconstruction accuracy and efficiency, conducting butane-flame simulations with different camera setups (6 to 18 cameras). The results show improved accuracy with more cameras, with 12 cameras achieving optimal computational efficiency (1.263) and low error rates. Verification experiments with 9, 12, and 15 cameras, using thermocouples, confirm that the 12-camera setup as the best, balancing efficiency and accuracy. This offers a feasible, cost-effective solution for real-world applications like engine testing and environmental monitoring, improving accuracy and resource management in temperature measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.284-287
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• 2000

We analyzed the 3-dimensional discharge characteristic in plasma display panel(PDP) cell using the 3-dimensional emission distribution of 828nm light measured by scanned point detecting method(SPDM). The emitted light distributions on the ITO electrode show the stronger light intensity near to the electrode gap than outside. Also, 828nm light is widely detected outside of the bus electrode. We consider that measurement using new SPDM is effective to analyze the discharge physics and propose the new panel structures.

• Science of Emotion and Sensibility
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• v.21 no.1
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• pp.35-44
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• 2018

This study suggests the sensing method of the Three-dimensional respiration rate sensor based on surface area changes, and exploring the design direction of the three-dimensional breathing sensor and the design orientation of the garment. To achieve this, two types of three-dimensional respiration rate sensor were produced, and the study of the dummy and the subjects studied. The study I investigated the possibility of measurement of the three-dimensional respiration sensor by the study variables of the sensor type and speed of respiration. The study II proposes a suitable type of sensor for each of the three measuring positions in addition to the study variables in the study I. To evaluate accuracy, reproducibility, and reliability of the three-dimensional respiration rate sensor, the BIOPAC was used to measure the respiration rate simultaneously with the three-dimensional respiration rate sensor. Through all these results of the experiment, it explored the possibility of measurement of the three-dimensional respiration sensor for the dummy. It also proposed a suitable type of sensor by measuring the respiration rate for the human body.

• Fashion & Textile Research Journal
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• v.24 no.4
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• pp.443-450
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• 2022

This study developed a three-dimensional helmet mold design software that can design helmets for treating the infant plagiocephaly (flat head syndrome) using three-dimensional head scan data. For this, the three-dimensional head data of sixth SizeKorea body measurement project as well as the data produced by a head modeling software were used to prepare the head shape data of plagiocephaly patients. A total of 14 landmarks and 10 dimensions of heads required for helmet mold shape design and plagiocephaly diagnosis were automatically measured using an anthropometric analysis software. Using the software developed in this study, plagiocephaly can be diagnosed not only visually by three-dimensional head data visualization but also quantitatively by calculating the medically defined indices such as cranial index, which measures the proportions of the head, and the cranial vault asymmetry index, which measures the asymmetry of the head. The basic shape of the helmet mold was automatically generated based on the head scan data. Additionally, it is possible to fine tune the shape of the mold to reflect individual characteristics by using a free form deformation technique. Finally, the designed helmet mold was converted into the data that can be printed on a three-dimensional printer for generating the actual prototype.

• Journal of the Korean Institute of Landscape Architecture
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• v.25 no.3
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• pp.56-65
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• 1997

This research was conducted to suggest some directions for desirable urban green space planning through 1) establishing a new classification system by examining the existing concept, problems and characteristics of green space and 2) defining the essence of green space environment and finding some analytical and evaluative methods through a clear establishment of functions, indicators of green space. In the research, measurements of the amount of green space was accompanied with measurements of green covered space, green volume, and the structure of greenery within the frame of vision. As result, three-dimensional measurement was possible, three-dimensional measurement was possible, which turned out to be more effective than the existing 2-dimensional measuring method. It is found that the ratio of green covered space is to proportional to the ratio of green volume in this study. Therefore in green space planning process it is desirable to consider the ratio of green volume all together.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.1
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• pp.101-112
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• 1994

The measurement of residual stress distribution of $Si_3N_4/SUS304$ joint was performed on 23 specimens with the same joint condition using PSPC type X-ray stress measurement system and the two-dimensional elastoplastic analysis using finite element method was also attempted. As results, residual stress distribution near the interface on the ceramic side of the joint was revealed quantitatively. Residual stress on the ceramic side of the joint was turned out to be tensional near the interface, maximum along the edge, varying in accordance with the condition of the joint and variance to be most conspicuous for the residual stress normal to the interface characterized by the stress singularities. In the vicinity of the interface, the high stress concentration occurs and residual stress distributes three-dimensionally. Therefore, the measured stress distribution differed remarkably from the result of the two-dimensional finite-element analysis. Especially at the center of the specimen near the interface, the residual stress, $\sigma_{x}$ obtained from the finite element analysis was compressive, whereas measurement using X-ray yielded tensile $\sigma_{x}$. Here we discuss two dimensional superposition model the discrepancy between the results from the two dimensional finite element analysis and X-ray measurement.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.28.2-28
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• 2001

Three dimensional shape measurement techniques are widely needed in industries for product quality monitoring and control. X-ray imaging method is a promising technology to achieve three-dimensional Information, both the surface and inner structure of an object, since it can overcome the limitations of conventional visual or optical methods such as an occlusion problem or surface reflection properties. In this paper, we propose three dimensional volume reconstruction method based on x-ray stereo imaging technology. Here, the stereo images of an object from two different views are taken by changing the object pose rather than moving imaging plane as in conventional stereo vision method. We propose a series of image processing techniques to extract the features efficiently from x-ray images, where the occluded features in case of normal camera vision could be found ...