• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3759-3763
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• 2021

In this study, 3" × 3" NaI(Tl) detector, which is widely used in gamma spectroscopy, was modeled with FLUKA code, and calculations required to determine the detector's energy resolution were reported. Photon beams with isotropic distribution with 59, 81, 302, 356, 511, 662, 835, 1173, 1275, and 1332 keV energy were used as radiation sources. The photon pulse height distribution of the NaI(Tl) without influence of its energy resolution obtained with FLUKA code has been converted into a real NaI(Tl) response function, using the necessary conversion process. The photon pulse height distribution simulated in the conversion process was analyzed using the ROOT data analysis framework. The statistical errors of the simulated data were found in the range of 0.2-1.1%. When the results, obtained with FLUKA and ROOT, are compared with the literature data, it is seen that the results are in good agreement with them. Thus, the applicability of this procedure has been demonstrated for the other energy values mentioned.

• Imaging Science in Dentistry
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• v.48 no.1
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• pp.11-19
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• 2018

Purpose: This study compared the diagnostic accuracy of cone-beam computed tomography (CBCT) scans obtained with 2 CBCT systems with high- and low-resolution modes for the detection of root perforations in endodontically treated mandibular molars. Materials and Methods: The root canals of 72 mandibular molars were cleaned and shaped. Perforations measuring 0.2, 0.3, and 0.4 mm in diameter were created at the furcation area of 48 roots, simulating strip perforations, or on the external surfaces of 48 roots, simulating root perforations. Forty-eight roots remained intact(control group). The roots were filled using gutta-percha (Gapadent, Tianjin, China) and AH26 sealer (Dentsply Maillefer, Ballaigues, Switzerland). The CBCT scans were obtained using the NewTom 3G (QR srl, Verona, Italy) and Cranex 3D (Soredex, Helsinki, Finland) CBCT systems in high- and low-resolution modes, and were evaluated by 2 observers. The chi-square test was used to assess the nominal variables. Results: In strip perforations, the accuracies of low- and high-resolution modes were 75% and 83% for NewTom 3G and 67% and 69% for Cranex 3D. In root perforations, the accuracies of low- and high-resolution modes were 79% and 83% for NewTom 3G and was 56% and 73% for Cranex 3D. Conclusion: The accuracy of the 2 CBCT systems was different for the detection of strip and root perforations. The Cranex 3D had non-significantly higher accuracy than the NewTom 3G. In both scanners, the high-resolution mode yielded significantly higher accuracy than the low-resolution mode. The diagnostic accuracy of CBCT scans was not affected by the perforation diameter.

• Korean Journal of Optics and Photonics
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• v.10 no.2
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• pp.138-145
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• 1999

By varying the beam current of a color CRT(cathode ray tube) monitor, the misconvergence, spot size, display luminance, and chromaticity coordinate of a white pattern were measured at 4 screen positions. The misconvergence was measured with a linear CCD (charge coupled-device). The resolution was obtained by using SQRI (square root integral) method. The misconvergence of a color monitor was not influenced by the beam current but by the screen position. The misconvergence on a screen perimeter caused the resolution to decrease.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.631-648
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• 1994

The purpose of this study was to investigate the effects of different types of orthodontic force on the root resorption and repair in rat molar. 77 rats were divided into three groups; The control group was not equiped with orthodontic appliance between incisor and first molar. The experimental group was subdivided into closed coil spring subgroup and elastic chain subgroup by the application methods of orthodontic force. Initial orthodontic force between incisor and first molar was 100g. Experimental period was 8 weeks; for 4 weeks the appliance was acting and for another 4 weeks, removed. Root resorption and repair in the root of first molar was examined by light microscope for histologic changes and by inductively coupled plasma spectroscopy(ICP) for quantitative changes. The results were as follows: 1. In the closed coil spring subgroup odontoclasts and root resolution were appeared one week earlier. 2. One week after orthodontic force was eliminated the repair response in the resorptive lacuna was seen in both subgroups. Delayed resorption was seen on the periphery of resorptive lacunae whereas reparative response was seen in the center of lacunae. A new resorption was seen one week after orthodontic force was eliminated. Root contour was partially restored by repairing of resorbed root. 3. The weight ratios of calcium and phosphorous to the sample were decreased during resorptive process but increased during repair process in both the orthodontic groups, but not more than the control group. 4. By different types of orthodontic force (closed coil spring or elastic chain) resorption process was affected but repair process was not.

• Imaging Science in Dentistry
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• v.43 no.3
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• pp.171-177
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• 2013

Purpose: The purpose of this study was to compare the efficacy of two imaging modes in a cone beam computed tomography (CBCT) system in detecting root fracture in endodontically-treated teeth with fiber posts or screw posts by selecting two fields of view. Materials and Methods: In this study, 78 endodontically-treated single canal premolars were included. A post space was created in all of them. Then the teeth were randomly set in one of 6 artificial dental arches. In 39 of the 78 teeth set in the 6 dental arches, a root fracture was intentionally created. Next, a fiber post and a screw post were cemented into 26 teeth having equal the root fractures. High resolution (HiRes) and standard zoom images were provided by a CBCT device. Upon considering the reconstructed images, two observers in agreement with each other confirmed the presence or absence of root fracture. A McNemar test was used for comparing the results of the two modes. Results: The frequency of making a correct diagnosis using the HiRes zoom imaging mode was 71.8% and in standard zoom was 59%. The overall sensitivity and specificity in diagnosing root fracture in the HiRes mode were 71.79% and 46.15% and in the standard zoom modes were 58.97% and 33.33%, respectively. Conclusion: There were no significant differences between the diagnostic values of the two imaging modes used in the diagnosis of root fracture or in the presence of root canal restorations. In both modes, the most true-positive results were reported in the post space group.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.52.1-52.1
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• 2019

The Helioseismic and Magnetic Imager (HMI) is the instrument of Solar Dynamics Observatory (SDO) to study the magnetic field and oscillation at the solar surface. The HMI image is not enough to analyze very small magnetic features on solar surface since it has a spatial resolution of one arcsec. Super resolution is a technique that enhances the resolution of a low resolution image. In this study, we use a method for enhancing the solar image resolution using a Deep-learning model which generates a high resolution HMI image from a low resolution HMI image (4 by 4 binning). Deep learning networks try to find the hidden equation between low resolution image and high resolution image from given input and the corresponding output image. In this study, we trained a model based on a very deep residual channel attention networks (RCAN) with HMI images in 2014 and test it with HMI images in 2015. We find that the model achieves high quality results in view of both visual and measures: 31.40 peak signal-to-noise ratio(PSNR), Correlation Coefficient (0.96), Root mean square error (RMSE) is 0.004. This result is much better than the conventional bi-cubic interpolation. We will apply this model to full-resolution SDO/HMI and GST magnetograms.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.70.4-70.4
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• 2019

Image super-resolution (SR) is a technique that enhances the resolution of a low resolution image. In this study, we use three SR models (RCAN, ProSRGAN and Bicubic) for enhancing solar SDO/HMI magnetograms using deep learning. Each model generates a high resolution HMI image from a low resolution HMI image (4 by 4 binning). The pixel resolution of HMI is about 0.504 arcsec. Deep learning networks try to find the hidden equation between low resolution image and high resolution image from given input and the corresponding output image. In this study, we trained three models with HMI images in 2014 and test them with HMI images in 2015. We find that the RCAN model achieves higher quality results than the other two methods in view of both visual aspects and metrics: 31.40 peak signal-to-noise ratio(PSNR), Correlation Coefficient (0.96), Root mean square error (RMSE) is 0.004. This result is also much better than the conventional bi-cubic interpolation. We apply this model to a full-resolution SDO/HMI image and compare the generated image with the corresponding Hinode NFI magnetogram. As a result, we get a very high correlation (0.92) between the generated SR magnetogram and the Hinode one.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.649-658
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• 1994

The purpose of this study was to evaluate the association between incisor root resolution and sex, age, extraction, the magnitude and direction of tooth movement. The sample consisted of 189 randomly selected orthodontic patients, receiving standard edgewise orthodontic treatment in three private orthodontic onces at San Francisco. Pre-treatment and post-treatment periapicals and cephalometric radiographs were digitized. Measurements and superimpositions were made utilizing a computerized cephalometric analysis program. The variables were statistically analyzed. The results were as follows: 1. Mean apical root resorption values were $0.77{\pm}2.08mm$ for upper right central incisor, $0.88{\pm}2.11mm$ for upper left central incisor, $-0.05{\pm}2.09mm$ for lower right central incisor and $0.11{\pm}1.85mm$ for lower left central incisor. Apical root resorption of upper incisor was greater than lowers. 2. No correlation was found between sex and apical root resorption. 3. Apical root resorptions in adolescents were smaller than those in adults. 4. Apical root resorption was not affected by extraction. 5. Apical root resorption values of upper incisor were correlated to the horizontal and vertical movement of apex; Apical root resorption values of lower incisor were correlated to the vertical movement of apex.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.375-387
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• 1995

The purpose of this study was to quantitatively evaluated experimental tooth root resorption for digital radiography. For this study, experimentally three root sites were used, and radiograms were taken with standardized apparatus. Digital imaging system were consisted of NEC PC-980l(computer), TRINITRON(monitor), SONY XC-711 CCD camera. The display monitor had a resolution of 512X512 pixels. The obtained results were as follows: 1. In the difference of the four X-ray film of the contrast correction, the contrast difference was one gray scale variation at mean value. 2. Viewing of the view box of the periapical radiographs, experimental tooth root resorption of the periapical area of the first premolar, middle of mesial surface of the first molar mesial root, middle of lingual surface of the first molar distal root were recognized by increased diameter. 3. On the analysis by histogram, the periapical area of the first premolar, the middle of mesial surface of the first molar mesial root were each recognized tooth root resorption of the 5,6,7 pixel, 2,4,5 pixel by increased diameter. 4. On the analysis by histogram, the middle of lingual surface of the first molar distal root was each recognized tooth root resorption of the none, 3,6 pixel by increased diameter.

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.379-385
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• 1999

The characteristics of image quality of a color CRT (cathode ray tube) monitor are studied by changing the contrast and brightness levels. The resolution is assessed by SQRI (square root integral) measured at 9 different combinations of the contrast and brightness levels. The chromaticity coordinates and luminances of red-green-blue channels as a function of the digital value are measured at these combinations and the relationships among the constant-channel chromaticity, color gamut, maximum luminance of a white point with the channel independence are analyzed. From the results, the optimized combination of levels is obtained.