• Title/Summary/Keyword: 3D imaging

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Radiologic study of the healing process of the extracted socket of beagle dogs using cone beam CT (Cone beam CT를 이용한 비글견 발치창 치유과정에 대한 방사선학적 연구)

  • Choi, Dong-Hoon;Lee, Wan;Kim, De-Sok;Lee, Byung-Do
    • Imaging Science in Dentistry
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    • v.39 no.1
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    • pp.19-25
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    • 2009
  • Purpose: To longitudinally observe the healing process of extracted socket and the alterations of the residual ridge in healthy adult dogs using cone beam CT (CBCT). Materials and Methods: The mandibular premolars of two beagle dogs were removed and the extraction sites were covered with the gingival tissue. CBCTs (3D X-ray CT scanner, Alphard vega, Asahi Co.) were taken at baseline and at 1 week interval for 12 weeks. Radiographic density of extracted wounds was measured on normalized images with a custom-made image analysis program. The amount of alveolar crestal resorption after the teeth extraction was measured with a reformatted three-dimensional image using CBCT. Bony healing pattern of extracted wound of each group was also longitudinally observed and analyzed. Results: Dimensional changes occurred during the first 6 weeks following the extraction of dogs' mandibular premolars. The reduction of the height of residual ridge was more pronounced at the buccal than at the lingual aspect of the extraction socket. Radiographic density of extracted wounds increased by week 4, but the change in density stabilized after week 6. New bone formation was observed at the floor and the peripheral side of extracted socket from week 1. The entrance of extracted socket was sealed by a hard-tissue bridge at week 5. Conclusion: The healing process of extracted wound involved a series of events including new bone formation and residual ridge resorption.

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Prediction of Cement Volume for Vertebroplasty Based on Imaging and Biomechanical Results

  • Lee, Sung-Jae;Tack, Gye-Rae;Lee, Seung-Yong;Jun, Bong-Jae;Lim, Do-Hyung;Shin, Jung-Woog;Kim, Jeong-Koo;Shin, Kyu-Chul
    • Journal of Mechanical Science and Technology
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    • v.15 no.7
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    • pp.1041-1050
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    • 2001
  • Control of bone cement volume (PMMA) may be critical for preventing complications in vertebroplasty, the percutaneous injection of PMMA into vertebra. The purpose of this study was to predict the optimal volume of PMMA injection based on CT images. For this, correlation between PMMA volume and textural features of CT images was examined before and after surgery to evaluate the appropriate PMMA amount. The gray level run length analysis was used to determine the textural features of the trabecular bone. Extimation of PMMA volume was done using 3D visualization with semi-automatic segmentation on postoperative CT images. Then, finite element (FE) models were constructed based on the CT image data of patients and PMMA volume. Appropriate material properties for the trabecular bone were assigned by converting BMD to elastic modulus. Structural reinforcement due to the changes in PMMA volume and BMD was assessed in terms of axial displacement of the superior endplate. A strong correlation was found between the injected PMMA volume and the area of the intertrabecular space and that of trabecular bone calculated from the CT images (r=0.90 and -0.90, respectively). FE results suggested that vertebroplasty could effectively reinforce the osteoporotic vertebra regardless of BMD or PMMA volume. Effectiveness of additional PMMA injection tended to decrease. For patients with BMD well lower than 50mg/ml, injection of up to 30% volume of the vertebral body is recommended. However, less than 30% is recommended otherwise to avoid any complications from excessive PMMA because the strength has already reached the normal level.

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A semi-automated method for integrating textural and material data into as-built BIM using TIS

  • Zabin, Asem;Khalil, Baha;Ali, Tarig;Abdalla, Jamal A.;Elaksher, Ahmed
    • Advances in Computational Design
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    • v.5 no.2
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    • pp.127-146
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    • 2020
  • Building Information Modeling (BIM) is increasingly used throughout the facility's life cycle for various applications, such as design, construction, facility management, and maintenance. For existing buildings, the geometry of as-built BIM is often constructed using dense, three dimensional (3D) point clouds data obtained with laser scanners. Traditionally, as-built BIM systems do not contain the material and textural information of the buildings' elements. This paper presents a semi-automatic method for generation of material and texture rich as-built BIM. The method captures and integrates material and textural information of building elements into as-built BIM using thermal infrared sensing (TIS). The proposed method uses TIS to capture thermal images of the interior walls of an existing building. These images are then processed to extract the interior walls using a segmentation algorithm. The digital numbers in the resulted images are then transformed into radiance values that represent the emitted thermal infrared radiation. Machine learning techniques are then applied to build a correlation between the radiance values and the material type in each image. The radiance values were used to extract textural information from the images. The extracted textural and material information are then robustly integrated into the as-built BIM providing the data needed for the assessment of building conditions in general including energy efficiency, among others.

Visibility Enhancement of Underwater Stereo Images Using Depth Image (깊이 영상을 이용한 수중 스테레오 영상의 가시성 개선)

  • Shin, Hyoung-Chul;Kim, Sang-Hoon;Sohn, Kwang-Hoon
    • Journal of Broadcast Engineering
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    • v.17 no.4
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    • pp.684-694
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    • 2012
  • In the underwater environment, light is absorbed and scattered by water and floating particles, which makes the underwater images suffer from color degradation and limited visibility. Physically, the amount of the scattered light transmitted to the image is proportional to the distance between the camera and the object. In this paper, the proposed visibility enhancement. method utilizes depth images to estimate the light transmission and the degradation factor by the scattered light. To recover the scatter-free images without unnatural artifacts, the proposed method normalizes the degradation factor based on the value of each pixel of the image. Finally, the scatter-free images are obtained by removing the scattered components on the image according to the estimated transmission. The proposed method also considers the color discrepancies of underwater stereo images so that the stereo images have the same color appearance after the visibility enhancement. The experimental results show that the proposed method improves the color contrast more than 5% to 14% depending on the experimental images.

Analysis on correlation between bone strength by FEA, micro-CT parameters and bone mineral density (유한요소법에 의한 골강도와 micro-CT 지표 및 골밀도간의 상관관계)

  • Yoon, Young-Nam;Lee, Wan;Lee, Byung-Do
    • Imaging Science in Dentistry
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    • v.37 no.1
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    • pp.53-59
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    • 2007
  • Purpose : Bone mineral density (BMD) and bone microarchitecture are important determinants for bone strength. Recently micro-CT have provided possibilities for measuring a variety of structural indices to characterize bone microarchitecture. The objective of this study was to compare the BMD and micro-CT parameters with Young's modulus calculated by finite element analysis (FEA) for the evaluation of bone strength. Materials and Methods Bone specimens were obtained from the 18 female rabbits aged 16 weeks. Of those, 36 samples (right and left femur) were selected for 3D micro-CT analysis $(ANT^{TM},\;SKYSCAN,\;Belgium)$ and BMD by PIXlmus 2 (GE Lunar Co. USA). Five microstructural parameters of micro-CT, such as trabecular thickness (Tb.Th), bone specific surface (BS/BV), percent bone volume (BV/TV), structure model index (SMI) and degree of anisotropy (DOA) were studied. Young's modulus was obtained by software program (ANSYS 9.0, ANSYS Inc, Canonsburg, PA) based on micro-CT three dimensional images. Results : Young's modulus assessed by FEA correlated significantly with Tb.Th, BV/TV, BS/BV and SMI respectively. Young's modulus showed higher correlation with these rnicrostructural parameters of micro-CT than BMD. Microstructural parameters except DOA showed significant correlations within the examined group. Conclusion The microarchitectural parameters o( micro-CT and BMD represented some informations in the evaluation of bone strength assessed by FEA.

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Molecular gas and star formation in early-type galaxies

  • Bureau, Martin
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.2
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    • pp.65-65
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    • 2011
  • Early-type galaxies represent the end point of galaxy evolution and, despite pervasive residual star formation, are generally considered "red and dead", that is composed exclusively of old stars with no star formation. Here, their molecular gas content is constrained and discussed in relation to their evolution, supporting the continuing importance of minor mergers and/or cold gas accretion. First, as part of the Atlas3D survey, the first complete, large, volume-limited survey of CO in normal early-type galaxies is presented. At least of 23% of local early-types possess a substantial amount of molecular gas, the necessary ingredient for star formation, independent of mass and environment but dependent on the specific stellar angular momentum. Second, using CO synthesis imaging, the extent of the molecular gas is constrained and a variety of morphologies is revealed. The kinematics of the molecular gas and stars are often misaligned, implying an external gas origin in over a third of all systems, more than half in the field, while external gas accretion must be shot down in clusters. Third, many objects appear to be in the process of forming regular kpc-size decoupled disks, and a star formation sequence can be sketched by piecing together multi-wavelength information on the molecular gas, current star formation, and young stars. Fourth, early-type galaxies do not seem to systematically obey all our usual prejudices regarding star formation (e.g. Schmidt-Kennicutt law, far infrared-radio continuum correlation), suggesting a greater diversity in star formation processes than observed in disk galaxies and the possibility of "morphological quenching". Lastly, a first step toward constraining the physical properties of the molecular gas is taken, by modeling the line ratios of density- and opacity-sensitive molecules in a few objects. Taken together, these observations argue for the continuing importance of (minor) mergers and cold gas accretion in local early-types, and they provide a much greater understanding of the gas cycle in the galaxies harbouring most of the stellar mass. In the future, better dust masses and dust-to-gas mass ratios from Herschel should allow to place entirely independent constraints on the gas supply, while spatially-resolved high-density molecular gas tracers observed with ALMA will probe the interstellar medium and star formation laws locally in a regime entirely different from that normally probed in spiral galaxies.

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Imaging on a Vapor Deposited Film by Photopolymerization of a Rod-Like Molecule Consisting of Two Diacetylenic Groups

  • Chang, Ji-Young;Kyung Seo;Cho, Hyun-Ju;Lee, Cheol-Ju;Lee, Changjin;Yongku Kang;Kim, Jaehyung
    • Macromolecular Research
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    • v.10 no.4
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    • pp.204-208
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    • 2002
  • A linear rod-like molecule, bis[4-(1,3-octadynyl)phenyl] terephthalate (2), consisting of two diacetylenic groups, was prepared. The unsymmetric diacetylene was prepared by the Cadiot-Chodkiewicz coupling reaction of 1-bromohexyne with 4-ethynylphenol and linked to a benzene core by an esterification reaction with terephthaloyl chloride in tetrahydrofuran. The thin film (200 nm thickness) of compound 2 was fabricated by the physical vapor deposition on a glass plate with a thermal evaporator. In the X-ray diffraction (XRD) study, the vapor deposited film on the glass plate showed peaks with d spacings of 19.4, 5.7, and 4.5 $\AA$. This XRD pattern was quite different from that observed for compound 2 isolated by recrystallization from methylene chloride/hexane. The vapor deposited film was polymerized by UV irradiation. Photopolymerization was carried out through a photomask, resulting in a patterned image, where the irradiated part became isotropic.

Surgical stent for dental implant using cone beam CT images (콘빔형 전산화단층영상을 이용한 치과임플란트 식립유도장치 개발)

  • Choi, Hyung-Soo;Kim, Gyu-Tae;Choi, Yong-Suk;Hwang, Eui-Hwan
    • Imaging Science in Dentistry
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    • v.40 no.4
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    • pp.171-178
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    • 2010
  • Purpose : The purpose of this study is to develop a surgical stent for dental implant procedure that can be easily applied and affordable by using cone beam computerized tomography (CBCT). Materials and Methods : Aluminum, Teflon-PFA (perfluoroalkoxy), and acetal (polyoxymethylene plastic) were selected as materials for the surgical stent. Among these three materials, the appropriate material was chosen using the CBCT images. The surgical stent, which could be easily placed into an oral cavity, was designed with chosen material. CBCT images of the new surgical stent on mandible were obtained using Alphard-3030 dental CT system (Asahi Roentgen Co., Ltd., Kyoto, Japan). The point of insertion was prescribed on the surgical stent with the multiplanar reconstruction software of OnDemand3D (CyberMed Inc., Seoul, Korea). Guide holes were made at the point of insertion on the surgical stent using newly designed guide jig. CBCT scans was taken for the second time to verify the accuracy of the newly designed surgical stent. Results : Teflon-PFA showed radiologically excellent image characteristics for the surgical stent. High accuracy and reproducibility of implantation were confirmed with the surgical stent. Conclusion : The newly designed surgical stent can lead to the accurate implantation and achieve the clinically predictable result.

Buccal cortical bone thickness on CBCT for mini-implant (치과용 콘빔CT영상에서 미니임플란트를 위한 협측피질골 두께)

  • Goo, Jong-Gook;Lim, Sung-Hoon;Lee, Byoung-Jin;Kim, Jae-Duk
    • Imaging Science in Dentistry
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    • v.40 no.4
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    • pp.179-185
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    • 2010
  • Purpose : Cortical bone thickness is one of the important factor in mini-implant stability. This study was performed to investigate the buccal cortical bone thickness at every interdental area as an aid in planning mini-implant placement. Materials and Methods : Two-dimensional slices at every interdental area were selected from the cone-beam computed tomography scans of 20 patients in third decade. Buccal cortical bone thickness was measured at 2, 4, and 6 mm levels from the alveolar crest in the interdental bones of posterior regions of both jaws using the plot profile function of $Ez3D2009^{TM}$ (Vatech, Yongin, Korea). The results were analyzed using by Mann-Whitney test. Results : Buccal cortical bone was thicker in the mandible than in the maxilla. The thickness increased with further distance from the alveolar crest in the maxilla and with coming from the posterior to anterior region in the mandible (p<0.01). The maximum CT value showed an increasing tendency with further distance from the alveolar crest and with coming from posterior to anterior region in both jaws. Conclusion : Interdental buccal cortical bone thickness varied in both jaws, however our study showed a distinct tendency. We expect that these results could be helpful for the selection and preparation of mini-implant sites.

Change in Each Vertebral Segment During Smartphone Usage with Both Hands while in the Standing Position

  • Cho, Sung-Hak;Moon, Hyun-Ju
    • PNF and Movement
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    • v.17 no.1
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    • pp.41-46
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    • 2019
  • Purpose: Continuous use of a smartphone increases the angle of forward bending of the user's cervical vertebrae, causing pain in the shoulders and back, including the thorax, lumbar region, and vertebrae. Although there are many studies on changes in the cervical spine due to smartphone usage, the changes in the shoulders, thoracolumbar spine, and pelvic have rarely been compared. The purpose of this study is to investigate the change in the spinal segments, shoulders, and pelvic when using a smartphone with both hands while in the standing position. Methods: This study was conducted on 35 adults in their twenties. The selection criteria for the subjects were limited to those in a similar age group, thus excluding posture differences according to age, and to those who did not have specific diseases or pain in the spinal and musculoskeletal system for 12 months prior to the study. In this study, we used a 3D spinal diagnostic imaging system (Back Mapper, Frickenhausen) to compare the changing conditions in each vertebral segment before and during smartphone usage with both hands while in the standing position. Posture differences according to smartphone usage were compared using the paired t-test for the motion of each spinal segment. Results: This study showed that the thoracic and lumbar angle increased posteriorly during smartphone usage (p<0.05). In addition, the anterior rotation angle of the shoulder bone significantly increased, but no significant difference occurred in the pelvic region. Conclusion: Based on the results of this study, smartphone usage with both hands while in the standing position showed that the spine, as a whole, forms a kyphotic curve. Therefore, we propose to present a postural guideline for correct smartphone usage, considering the change in each vertebral segment.