• The Journal of Advanced Prosthodontics
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• v.6 no.1
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• pp.22-29
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• 2014

PURPOSE. This study aimed to investigate the potential clinical application of digitized silicone rubber impressions by comparing the accuracy of zirconia 3-unit fixed partial dentures (FPDs) fabricated from 2 types of data (working model and impression) obtained from a laser scanner. MATERIALS AND METHODS. Ten working models and impressions were prepared with epoxy resin and vinyl polysiloxane, respectively. Based on the data obtained from the laser scanner (D-700; 3Shape A/S, Copenhagen, Denmark), a total of 20 zirconia frameworks were prepared using a dental CAD/CAM system (DentalDesigner; 3shape A/S, Copenhagen, Denmark / Ener-mill, Dentaim, Seoul, Korea). The silicone replicas were sectioned into four pieces to evaluate the framework fit. The replicas were imaged using a digital microscope, and the fit of the reference points (P1, P2, P3, P4, P5, P6, and P7) were measured using the program in the device. Measured discrepancies were divided into 5 categories of gaps (MG, CG, AWG, AOTG, OG). Data were analyzed with Student's t-test ($\alpha$=0.05), repeated measures ANOVA and two-way ANOVA (${\alpha}=0.05$). RESULTS. The mean gap of the zirconia framework prepared from the working models presented a narrower discrepancy than the frameworks fabricated from the impression bodies. The mean of the total gap in premolars (P=.003) and molars (P=.002) exhibited a statistical difference between two groups. CONCLUSION. The mean gap dimensions of each category showed statistically significant difference. Nonetheless, the digitized impression bodies obtained with a laser scanner were applicable to clinical settings, considering the clinically acceptable marginal fit ($120{\mu}m$).

• The korean journal of orthodontics
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• v.51 no.2
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• pp.95-104
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• 2021

Objective: To evaluate the trueness and precision of full-arch scans acquired using five intraoral scanners and investigate the factors associated with the dimensional accuracy of the intraoral scan data. Methods: Nine adult participants (mean age, 34.3 ± 8.3 years) were recruited. Four zirconium spheres (Ø 6 mm) were bonded to the canines and the molars. Following acquisition of reference scans using an industrial-grade scanner, five intraoral scanners, namely i500, CS3600, Trios 3, iTero, and CEREC Omnicam, were used to scan the arches. Linear distances between the four reference spheres were automatically calculated, and linear mixed model analysis was performed to compare the trueness and precision of the intraoral scan data among the different scanners. Results: The absolute mean trueness and precision values for all intraoral scanners were 76.6 ± 79.3 and 56.6 ± 52.4 ㎛, respectively. The type of scanner and the measured linear distances had significant effects on the accuracy of the intraoral scan data. With regard to trueness, errors in the intermolar dimension and the distance from the canine to the contralateral molar were greater with Omnicam than with the other scanners. With regard to precision, the error in the linear distance from the canine to the molar in the same quadrant was greater with Omnicam and CS3600 than with the other scanners. Conclusions: The dimensional accuracy of intraoral scan data may differ significantly according to the type of scanner, with the amount of error in terms of trueness being clinically significant.

• Journal of the Korea Institute of Building Construction
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• v.22 no.2
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• pp.171-182
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• 2022

The regular assessment of a building is important to understand structural safety and latent risk in the early stages of building life cycle. However, methods of traditional assessment are subjective, atypical, labor-intensive, and time-consuming and as such the reliability of these results has been questioned. This study proposed a method to bring accurate results using a 3D laser scanner and integrate them in Building Information Modeling (BIM) to visualize defective condition. The specific process for this study was as follows: (1) semi-automated data acquisition using 3D laser scanner and python script, (2) scan-to-BIM process, (3) integrating and visualizing defective conditions data using dynamo. The method proposed in this study improved efficiency and productivity in a building assessment through omitting the additional process of measurement and documentation. The visualized 3D model allows building facility managers to make more effective decisions. Ultimately, this is expected to improve the efficiency of building maintenance works.

• The Korean Journal of Nuclear Medicine
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• v.38 no.6
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• pp.528-531
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• 2004

Purpose: PET has some disadvantage in the imaging of small animal due to poor resolution. With the advent of microPET scanner, it is possible to image small animals. However, the image quality was not good enough as human image. Due to larger brain, cat brain imaging was superior to mouse or rat. In this study, we established the cat brain infarction model and evaluate it and its temporal charge using microPET scanner. Materials and Methods: Two adult male cats were used. Anesthesia was done with xylazine and ketamine HCl. A burr hole was made at 1cm right lateral to the bregma. Collagenase type IV 10 ${\mu}l$ was injected using 30 G needle for 5 minutes to establish the infarction model. $^{18}F$-FDG microPET (Concorde Microsystems Inc., Knoxville, TN) scans were performed 1, 11 and 32 days after the infarction. In addition, $^{18}F$-FDG PET scans were performed using human PET scanner (Gemini, Philips medical systems, CA, USA) 13 and 47 days after the infarction. Results: Two cat brain infarction models were established. The glucose metabolism of an infarction lesion improved with time. An infarction lesion was also distinguishable in the human PET scan. Conclusion: We successfully established the cat brain infarction model and evaluated the infarcted lesion and its temporal change using $^{18}F$-FDG microPET scanner.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.335-336
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• 2011

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.1
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• pp.14-24
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• 2022

The aim of the present study is to evaluate the validity of orthodontic measurements including tooth width, Bolton ratio, overjet and overbite on the digital dental models. Dental models of the subjects aged 12 to 18 were obtained in 3 different forms, which were conventional stone model, digital model created with Freedom HD model scanner, and digital model produced with CS3600 intraoral scanner. After measurements were made on the models, reliability and reproducibility of the measurements were evaluated by using intraclass correlation coefficient, while validity was assessed with paired t-test. As a result, significant reliability and reproducibility were verified, with intraclass correlation coefficient exceeding 0.750 in all groups. Measurements of the model scanned group showed an adequate validity in overall and anterior Bolton ratio, overjet, and overbite. Intraoral scanned models showed an adequate validity in anterior Bolton ratio, and overjet. Measurement on intraoral scanned digital models can be considered as an alternative for young children who have difficulty in taking impression. Furthermore, careful considerations on measurement error should be made in clinical situations.

• The Journal of Korea Robotics Society
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• v.4 no.2
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• pp.130-138
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• 2009

Recently, people tracking technology is being required to various area including security application. This paper suggests a method to track people with multiple laser scanners to detect the waist part of human. Multi-target model and Kalman filter based estimation are employed to track the human movement. The proposed method is applied to a novel system to monitor the entrance area and to filter out the trespasser to pass through the door without identification. Experiments for various cases are performed to verify the usefulness of the developed system.

• Korean Journal of Computational Design and Engineering
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• v.17 no.6
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• pp.436-442
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• 2012

Traumatic loading during car accidents or sports activities can lead to cervical spinal cord injury. Experiments in spinal cord injury research are mainly carried out on rabbit or rat. Finite element models that include the rat cervical spinal cord and adjacent soft tissues should be developed for efficient studies of mechanisms of spinal cord injury. Images of a rat were obtained from high resolution MRI scanner. Polygonal surfaces were extracted structure by structure from the MRI data using the ITK-SNAP volume segmentation software. These surfaces were converted to Non-uniform Rational B-spline surfaces by the INUS Rapidform rapid prototyping software. Rapidform was also used to generate a thin shell surface model for the dura mater which sheathes the spinal cord. Altair's Hypermesh pre-processor was used to generate finite element meshes for each structure. These processes in this study can be utilized in modeling of other biomedical tissues and can be one of examples for reverse engineering on biomechanics.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.94-101
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• 1996

When objects are scanned spatially by a laser-beam and mechanical mirror scanners, spatial information can be obtained, and then it is improtant to accurately obtain the parameters relating the light source and camera positions, etc.. In this paper, a calibration technique is presented for correction of measuremtn errors in a three-dimensional laser scanner system with two galvanometers. First, a model of the systematic errors is developed based on the geometry of the scanning system. Calibration parameter values are then iteratively adjusted with coarse-fine search in order to minimize errors (evaluation function) between measured and computed distances. It is shown that this correction method results in measurement precision suitable for practical use.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.652-655
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• 2004

The geometry of satellite image captured by linear pushbroom scanner is different from that of frame camera image. Since the exterior orientation parameters for satellite image will vary scan line by scan line, the epipolar geometry of satellite image differs from that of frame camera image. As we know, 2D affine orientation for the epipolar image of linear pushbroom scanners system are well-established by using the collinearity equation (Testsu Ono, 1999). Also, another epipolar geometry of linear pushbroom scanner system is recently established by Habib(2002). He reported that the epipolar geometry of linear push broom satellite image is realized by parallel projection based on 2D affine models. Here, in this paper, we compared the Ono's method with Habib's method. In addition, we proposed a method that generates epipolar resampled images. For the experiment, IKONOS stereo images were used in generating epipolar images.