• Current Optics and Photonics
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• v.5 no.1
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• pp.40-44
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• 2021

In this paper, LED arrays with segmented mirrors and a mask are presented as a new dark-field illuminator for reflective Fourier ptychographic microscopy (FPM). The illuminator can overcome the limitations of the size and the position of samples that the dark-field illuminator using a parabolic mirror has had. The new concept was demonstrated by measuring a USAF 1951 target, and it resolved a pattern in group 10 element 6 (274 nm) in the USAF target. The new design of the dark-field illuminator can enhance competitiveness of the reflective FPM as a versatile measurement method in industry.

• The korean journal of orthodontics
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• v.53 no.1
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• pp.54-64
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• 2023

This case report describes skeletal anchorage-supported maxillary protraction performed with the Alternate Rapid Maxillary Expansion and Constriction (AltRAMEC) protocol over a treatment duration of 14 months in a 16-year-old female patient who was in the late growth-development period. Miniplates were applied to the patient's aperture piriformis area to apply force from the protraction appliance. After 9 weeks of following the Alt-RAMEC protocol, miniplates were used to transfer a unilateral 500-g protraction force to a Petit-type face mask. A significant improvement was observed in the soft tissue profile in measurements made both cephalometrically and in three dimensional photographs. Subsequently, the second phase of fixed orthodontic treatment was started and the treatment was completed with the retention phase. Following treatment completion, occlusion, smile esthetics, and soft tissue profile improved significantly in response to orthopedic and orthodontic treatment.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.4
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• pp.359-371
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• 2007

Recently, many studies were reported accurate analysis of facemask effect due to the development of the personal computers and computer programs. The aim of this study is appropriate protraction direction of facemask using finite element study with computer aided design and computer aided measurement. The construction of the three dimensional FEM was based on the computer tomography(CT) scans of 13.5 year-old male subject. Protraction force of 500 mg was applied at 0, 30, 60 and 90 degrees downwards to the Frankfort horizontal plane, and maxillary displacement and stress distribution were measured. When 60 degree force was applied, it showed forward movement of premolar roots area and downward movement of anterior nasomaxillary area, and others showed clockwise rotation movement of the nasomaxillary complex. Finally, we can produce the protraction of maxillary bone without rotation of maxilla about 60 degrees.

• Korean Journal of Optics and Photonics
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• v.12 no.1
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• pp.17-24
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• 2001

Two-dimensional binary-phase diffraction gratings which can be employed to fabricate two- and three-dimensional periodic structures are designed and analyzed using rigorous coupled-wave analysis. These gratings serve as phase-masks which generate several diffracted waves from a normally incident beam and thus can produce a periodic interference pattern in space via nearfield holography. The properties of the diffracted beams can be controlled by varying the polarization and wavelength of the incident beam, surface-profile, groove depth and duty cycle of the mask. For the two-dimensional structure, optimum results can be obtained when the diffraction efficiency of the zero-order beam is minimized while that of the first-order maximized. On the other hand, when the diffraction efficiency of the zero-order is appreciable or even greater than other orders, we can obtain a variety of three-dimensional interference patterns which may be used to fabricate photonic crystals of tetragonal-body-centered and hexagonal structures in a submicron scale. scale.

• Progress in Medical Physics
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• v.32 no.4
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• pp.172-178
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• 2021

Purpose: This study aimed to develop a deep learning architecture combining two task models to generate synthetic computed tomography (sCT) images from low-tesla magnetic resonance (MR) images to improve metallic marker visibility. Methods: Twenty-three patients with cervical cancer treated with intracavitary radiotherapy (ICR) were retrospectively enrolled, and images were acquired using both a computed tomography (CT) scanner and a low-tesla MR machine. The CT images were aligned to the corresponding MR images using a deformable registration, and the metallic dummy source markers were delineated using threshold-based segmentation followed by manual modification. The deformed CT (dCT), MR, and segmentation mask pairs were used for training and testing. The sCT generation model has a cascaded three-dimensional (3D) U-Net-based architecture that converts MR images to CT images and segments the metallic marker. The performance of the model was evaluated with intensity-based comparison metrics. Results: The proposed model with segmentation loss outperformed the 3D U-Net in terms of errors between the sCT and dCT. The structural similarity score difference was not significant. Conclusions: Our study shows the two-task-based deep learning models for generating the sCT images using low-tesla MR images for 3D ICR. This approach will be useful to the MR-only workflow in high-dose-rate brachytherapy.

• Journal of Cadastre & Land InformatiX
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• v.48 no.2
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• pp.213-225
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• 2018

For constructing three-dimensional (3D) spatial information occlusion region problem arises in the process of taking the texture of the building. In order to solve this problem, it is necessary to investigate the automation method to automatically recognize the occlusion region, issue it, and automatically complement the texture. In fact there are occasions when it is possible to generate a very large number of structures and occlusion, so alternatives to overcome are being considered. In this study, we attempt to apply an approach to automatically create an occlusion region based on learning by patterning the blocked region using the recently emerging deep learning algorithm. Experiment to see the performance automatic detection of people, banners, vehicles, and traffic lights that cause occlusion in building walls using two advanced algorithms of Convolutional Neural Network (CNN) technique, Faster Region-based Convolutional Neural Network (R-CNN) and Mask R-CNN. And the results of the automatic detection by learning the banners in the pre-learned model of the Mask R-CNN method were found to be excellent.

• Journal of the Optical Society of Korea
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• v.19 no.3
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• pp.248-254
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• 2015

In this paper we propose an improved version of the computational integral imaging reconstruction (CIIR) for visualizing a partially occluded object by utilizing an image inpainting technique. In the proposed method the elemental images for a partially occluded three-dimensional (3D) object are recorded through the integral imaging pickup process. Next, the depth of occlusion within the elemental images is estimated using two different CIIR methods, and the weight mask pattern for occlusion is generated. After that, we apply our image inpainting technique to the recorded elemental images to fill in the occluding area with reliable data, using information from neighboring pixels. Finally, the inpainted elemental images for the occluded region are reconstructed using the CIIR process. To verify the validity of the proposed system, we carry out preliminary experiments in which faces are the objects. The experimental results reveal that the proposed system can dramatically improve the quality of a reconstructed CIIR image.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.71-77
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• 1996

This paper describes the development of on the machine measuring(OMM) system which can directlry measure the three dimensional machined dimensilnal accuracy using scanning probe in milling machine. Two algolithms, continuous path(CP) measurement using UC program and CAD data assisted point to point(PTP) measurement, were developed regarding specification of scanning probe. The OMM system was contructed to verify the developed system suing the proposed algorithm, and actually measured three kinds of machined TV shadow mask molds. The developed system was evaluated it's repeatability and compared with the current measurement system of CMM(Coording Measuring Machine) in terms of relative accuracy and time reduction and productivity increase.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.3
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• pp.176-181
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• 2012

Due to the high etch rate and low fabrication cost, the wet etching of silicon using KOH etchant is widely used in MEMS fabrication area. However, anisotropic etch characteristic obstruct intuitional mask design and compensation structures are required for mask design level. Therefore, the accurate modeling for various types of silicon surface is essential for fabrication of three-dimensional MEMS structure. In this paper, we modeled KOH etch profile for MEMS based energy harvester using fuzzy logic. Modeling results are compared with experimental results and it is applied to design of compensation structure for MEMS based energy harvester. Through Fuzzy inference approaches, developed model showed good agreement with the experimental results with limited etch rate information.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.58-67
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• 2000

Electron gun heaters are used to heat a cathode in video(TV) monitors. Major defects of the electron gun heaters include dimensional inaccuracy and pollution with dirty materials. In this paper, to save the labor and time being taken to inspect the heaters, a machine vision system is considered. For the system, a new algorithm is developed to measure the 9 different dimensions of each heater and to detect polluted defects. The algorithm consists of three stages. In the first stage, the center of the heater image is obtained and then its boundary detection is performed. For the efficient boundary detection, a mask called the sum mask is used. In the second stage of the algorithm, a set of fiducial points are determined on the boundary image. Finally, using the fiducial points specified dimensions are measured and the amount of polluted area is computed in the third stage. The performance of the algorithm is evaluated for a set of real specimens. The results indicate that measurements obtained by the algorithm satisfy the tolerance limits fur most of the dimensions and the algorithm detects the polluted defects successfully.