• Imaging Science in Dentistry
• /
• v.50 no.4
• /
• pp.323-330
• /
• 2020

Purpose: The mastoid region is ideal for studying sexual dimorphism due to its anatomical position at the base of the skull. This study aimed to determine sex in the Iranian population based on measurements of the mastoid process using different data mining algorithms. Materials and Methods: This retrospective study was conducted on 190 3-dimensional cone-beam computed tomographic (CBCT) images of 105 women and 85 men between the ages of 18 and 70 years. On each CBCT scan, the following 9 landmarks were measured: the distance between the porion and the mastoidale; the mastoid length, height, and width; the distance between the mastoidale and the mastoid incision; the intermastoid distance (IMD); the distance between the lowest point of the mastoid triangle and the most prominent convex surface of the mastoid (MF); the distance between the most prominent convex mastoid point (IMSLD); and the intersecting angle drawn from the most prominent right and left mastoid point (MMCA). Several predictive models were constructed and their accuracy was compared using cross-validation. Results: The results of the t-test revealed a statistically significant difference between the sexes in all variables except MF and MMCA. The random forest model, with an accuracy of 97.0%, had the best performance in predicting sex. The IMSLD and IMD made the largest contributions to predicting sex, while the MMCA variable had the least significant role. Conclusion: These results show the possibility of developing an accurate tool using data mining algorithms for sex determination in the forensic framework.

• Smart Media Journal
• /
• v.10 no.1
• /
• pp.32-38
• /
• 2021

Image classification through deep learning on the image from photographs has been a very active research field for the past several years. In this paper, we propose a method of automatically discriminating stone images from domestic source through deep learning, which is to use Python's hash library to scan 300×300 pixel photo images of granites such as Hwangdeungseok, Goheungseok, and Pocheonseok, performing data preprocessing to create learning images by examining duplicate images for each stone, removing duplicate images with the same hash value as a result of the inspection, and deep learning by stone. In addition, to utilize VGGNet, the size of the images for each stone is resized to 224×224 pixels, learned in VGG16 where the ratio of training and verification data for learning is 80% versus 20%. After training of deep learning, the loss function graph and the accuracy graph were generated, and the prediction results of the deep learning model were output for the three kinds of stone images.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.50 no.2
• /
• pp.119-125
• /
• 2022

In this paper, we present design, implementation and test results of CTM (Chirp Transceiver Module) EM (Engineering Model) for C-Band SAR (Synthetic Aperture Radar) Payload. The CTM is designed to operate dual frequency scan method that simultaneously operate two frequencies in each 50MHz bandwidth to achieve 120Km swath with 10m resolution at about 500Km altitude. The CTM used radiation tolerant RTG4 FPGA for space environment, and implemented with the Parallel DDS (PDDS) method which uses a small memory capacity compared to the memory-map method. Test results show high purity chirp signal generation and excellent IRF performance from received chirp signal after direct digital conversion.

• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.1075-1084
• /
• 2022

The use of Hi-Tech in cultural heritage preservation and the promotion of cultural heritage values in general, particularly artifacts, opens new opportunities for attracting tourists while also posing a challenge due to the need to reward high-quality excursions to visitors historical and cultural values. Building Information Modeling (BIM) and Hi-Tech in new building management have been widely adopted in the construction industry; however, Historic Building Information Modeling (HBIM) is an exciting challenge in 3D modeling and building management. For those reasons, the Scan-to-HBIM approach involves generating an HBIM model for existing buildings from the point cloud data collected by Terrestrial 3D Laser Scanner integrated with Virtual Reality (VR), Augmented Reality (AR), contributes to spatial historic sites simulation for virtual experiences. Therefore, this study aims to (1) generate the application of Virtual Reality, Augmented Reality to Historic Building Information Modeling - based workflows in a case study which is a monument in the city; (2) evaluate the application of these technologies to improve awareness of visitors related to the promotion of historical values by surveying the experience before and after using this application. The findings shed light on the barriers that prevent users from utilizing technologies and problem-solving solutions. According to the survey results, after experiencing virtual tours through applications and video explanations, participant's perception of the case study improved. When combined with emerging Hi-Tech and immersive interactive games, the Historic Building Information Modeling helps increase information transmission to improve visitor awareness and promote heritage values.

• Journal of Korean Society of Disaster and Security
• /
• v.15 no.4
• /
• pp.71-78
• /
• 2022

Recently, mountain disasters such as landslides and debris flows have flowed along mountain streams and hit residential areas and roads, increasing damage. In this study, in order to reduce damage and analyze causes of mountain disasters, field surveys and Terrestrial LiDAR terrain analysis were conducted targeting debris flow areas, and debris flow flow processes were simulated using FLO-2D and RAMM models, which are numerical models of debris flows. In addition, the debris flow deposition area was calculated and compared and analyzed with the actual occurrence section. The sedimentation area of the debris flow generation section of the LiDAR scan data was estimated to be approximately 21,336 ㎡, and was analyzed to be 20,425 ㎡ in the FLO-2D simulation and 19,275 ㎡ in the case of the RAMMS model. The constructed topographical data can be used as basic data to secure the safety of disaster risk areas.

• The Journal of Advanced Prosthodontics
• /
• v.15 no.6
• /
• pp.302-314
• /
• 2023

PURPOSE. The aim of this study was to classify the shapes of retromolar pads and assess their morphometric differences using a 3D model. MATERIALS AND METHODS. Two hundred fully edentulous or Kennedy Class I partially edentulous patients (400 retromolar pads) were enrolled. Scan data of the definitive mandibular casts produced through functional impressions were obtained using a 3D laser scanner. Seven parameters (transverse diameter, longitudinal diameter, transverse-contour length, longitudinal-contour length, longitudinal/transverse diameter ratio, longitudinal/transverse-contour length ratio, and angle of the retromolar pad line to the residual alveolar ridge line) were measured using image analysis software. Subsequently, the pads were classified according to the shape. Statistical analyses were performed using 95% confidence intervals. RESULTS. Classifying the retromolar pads into three shapes led to high intra-examiner reliability (Cronbach's alpha = 0.933). The pear shape was the most common (56.5%), followed by oval/round (27.7%) and triangular (15.8%) shapes. There were no significant differences between the left and right sides according to the shape and no significant differences in any parameter according to age. The transverse diameter and longitudinal/transverse diameter ratio differed between sexes (P < .05). The triangular shape had a significantly different transverse diameter, transverse-contour length, longitudinal/transverse diameter ratio, and longitudinal/transverse-contour length ratio compared with the pear and oval/round shapes (P < .05). CONCLUSION. From a clinical reliability standpoint, classifying retromolar pads into three shapes (oval/round, pear-shaped, and triangular) is effective. The differences in the sizes among the shapes were attributed to the transverse measurement values.

• Progress in Medical Physics
• /
• v.19 no.1
• /
• pp.49-55
• /
• 2008

This study aims to conduct the comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber used for measuring radiation dose in the MDCT, as well as of $CTDI_w$ according to temperature and pressure correction factors in the CT room. A comparative analysis was conducted based on the measured MDCT (GE light speed plus 4 slice, USA) data using head and body CT dosimetric phantom, and Model 2026C electrometer (RADICAL 2026C, USA) calibrated on March 21, 2007. As a result, the $CTDI_w$ value which reflected calibration factors, as well as correction factors of temperature and pressure, was found to be the range of $0.479{\sim}3.162mGy$ in effective radiation dose than the uncorrected values. Also, under the routine abdomen routine CT image acquisition conditions used in reference hospitals, patient effective dose was measured to indicate the difference of the maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the correction of temperature and pressure of the CT room are crucial in measuring and calculating patient effective dose. Thus, to measure patient radiation dose accurately, the detailed information should be made available regarding not only the temperature and pressure of the CT room, but also the humidity and recombination factor, characteristics of X-ray beam quality, exposure conditions, scan region, and so forth.

• Restorative Dentistry and Endodontics
• /
• v.32 no.1
• /
• pp.19-27
• /
• 2007

The purpose of this study is to develope new dental color-space system. Twelve kinds of dental composites and one kind of dental porcelain were used in this study. Disk samples (15 mm in diameter, 4 mm in thickness) of used materials were made and sample's CIE $L^*a^*b^*$ value was measured by Spectrocolorimeter (MiniScan XE plus, Model 4000S, diffuse/$8^{\circ}$ viewing mode, 14.3 mm Port diameters, Hunter Lab USA) The range of measured color distribution was analyzed. All the data were applied in the form of T### which is expression unit in CNU Cons Dental Color Chart. The value of $L^*$ lies between 80.40 and 52.70. The value of $a^*$ are between 10.60 and 3.60 and $b^*$ are between 28.40 and 2.21. The average value of $L^*$ is 67.40, and median value is 67.30. The value of $a^*$ are 2.89 and 2.91 respectively. And for the $b^*$, 14.30 and 13.90 were obtained. The data were converted to T### that is the unit count system in CNU-Cons Dental Color Chart. The value of $L^*$ is converted in the first digit of the numbering system. Each unit is 2.0 measured values. The second digit is the value of $a^*$ and is converted new number by 1.0 measured value. For the third digit $b^*$ is replaced and it is 2.0 measured unit apart. T555 was set to the value of $L^*$ ranging from 66.0 to 68.0, value of $a^*$ ranging from 3 to 4 and $b^*$ value ranging from 14 to 16.

• The Journal of the Korea Contents Association
• /
• v.9 no.11
• /
• pp.280-288
• /
• 2009

This study is to design and produce a detailed model for volume variety of three dimensional reconstruction images and to evaluate the changes of volume, area and the length of the model in the process of the reconstruction of RTP system. CT simulation was operated at the thickness of 1.25, 2.5, 5, 10mm and average, standard deviation of scan direction(X), thickness(Y), table movement direction(Z), area(A), and volume(V) of the three dimensional volume rendering, were measured according to the shape and thickness of the phantoms. As a result, at the thickness of 1.25, 2.5min, the phantom's shape decreased maximum 0.13cm(p<0.05) to the direction of X, Y, Z and length, area, volume decreased 0.1cm, $0.8cm^2$, $3.99cm^3$ which led to an approximate image of the phantoms. However, at the thickness of 5, 10mm, the phantom of the original form decreased maximum 0.58cm(p<0.05) and volume, area, length decreased maximum 0.45cm, $8.21cm^2$, $11.03cm^3$. Volume varieties according to the thickness and shape of the phantoms have occurred diversely, when CT simulation was operated, and it is considered that a clinically appropriate volume rendering can be obtained only when the thickness is below 3mm.

• The Journal of Advanced Prosthodontics
• /
• v.9 no.5
• /
• pp.341-349
• /
• 2017

PURPOSE. This study evaluated the accuracies of different bite registration techniques for implant-fixed prostheses using three dimensional file analysis. MATERIALS AND METHODS. Implant fixtures were placed on the mandibular right second premolar, and the first and second molar in a polyurethane model. Aluwax (A), Pattern Resin (P), and Blu-Mousse (B) were used as the bite registration materials on the healing abutments (H) or temporary abutments (T). The groups were classified into HA, HP, HB, TA, TP, and TB according to each combination. The group using the bite impression coping was the BC group; impression taking and bite registration were performed simultaneously. After impression and bite taking, the scan bodies were connected to the lab analogs of the casts. These casts were scanned using a model scanner. The distances between two reference points in three-dimensional files were measured in each group. One-way ANOVA and Duncan's test were used at the 5% significance level. RESULTS. The smallest distance discrepancy was observed in the TB group using the temporary abutments. The Blu-Mousse and HP groups showed the largest distance discrepancy. The TB and BC groups showed a lower distance discrepancy than the HP group (P=.001), and there was no significant difference between the groups using the temporary abutments and healing abutments (P>.05). CONCLUSION. Although this study has limitations as an in-vitro investigation, the groups using the temporary abutments to hold the Blu-Mousse record and bite impression coping showed greater accuracy than the group using the healing abutments to hold the pattern resin record.