• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.210-217
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• 2020

PURPOSE. The purpose of the study is to evaluate the repeatability and reproducibility of the abutment angle using a blue light scanner. MATERIALS AND METHODS. 0°, 6°, and 10° wax cast abutment dies were fabricated. Each of the silicone impression was produced using the replicable silicone. Each study die was constructed from the prepared replicable stone used for scans. 3-dimensional data was obtained after scanning the prepared study dies for the repeatability by using the blue light scanner. The prepared 3-dimensional data could have the best fit alignment using 3-dimensional software. For reproducibility, each abutment was used as the first reference study die, and then it was scanned five times per each. 3-dimensional software was used to perform the best fit alignment. The data obtained were analyzed using a nonparametric Kruskal-Wallis H test (α=.05), post hoc Mann-Whitney U test, and Bonferroni correction (α=.017). RESULTS. The repeatability of 0°, 6°, and 10° abutments was 3.9, 4.4 and 4.7 ㎛, respectively. Among them, the 0° abutment had the best value while the 10° abutment showed the worst value. There was a statistically significant difference (P<.05). The reproducibility of 0°, 6°, and 10° abutments was 6.1, 5.5, and 5.3 ㎛, respectively. While the 10° abutment showed the best value, the 0° abutment showed the worst value. However, there was no statistically significant difference (P>.05). CONCLUSION. In repeatability, the 0° abutment showed a positive result. In reproducibility, the 10° abutment achieved a positive result.

• The Journal of Advanced Prosthodontics
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• v.10 no.4
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• pp.328-334
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• 2018

PURPOSE. To evaluate the reproducibility of scan-based abutments using a blue light model scanner. MATERIALS AND METHODS. A wax cast abutment die was fabricated, and a silicone impression was prepared using a silicone material. Nine study dies were constructed using the prepared duplicable silicone, and the first was used as a reference. These dies were classified into three groups and scanned using a blue light model scanner. The first three-dimensional (3D) data set was obtained by scanning eight dies separately in the first group. The second 3D data set was acquired when four dies were placed together in the scanner and scanned twice in the second group. Finally, the third 3D data set was obtained when eight dies were placed together in the scanner and scanned once. These data were then used to define the data value using third-dimension software. All the data were then analyzed using the non-parametric Kruskal-Wallis H test (${\alpha}=.05$) and the post-hoc Mann-Whitney U-test with Bonferroni's correction (${\alpha}=.017$). RESULTS. The means and standard deviations of the eight dies together were larger than those of the four dies together and of the individual die. Moreover, significant differences were observed among the three groups (P<.05). CONCLUSION. With larger numbers of abutments scanned together, the scan becomes more inaccurate and loses reproducibility. Therefore, scans of smaller numbers of abutments are recommended to ensure better results.

• Korean Journal of Ecology and Environment
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• v.47 no.3
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• pp.232-238
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• 2014

We have developed a non-destructive, touch-free method for estimating leaf areas with a structured-light three-dimensional (3D) scanner. When the surfaces of soybean leaves were analyzed with both the 3D scanner and a leaf area meter, the results were linearly related ($R^2=0.90$). The strong correlation ($R^2=0.98$) was calculated between shoot fresh weights and leaf areas when the scanner was employed during growth stages V1 to V4. We also found that leaf areas measured by the scanner could be used to detect changes in growth responses to abiotic stress. Whereas under control conditions the areas increased over time, salt and drought treatments were associated with reductions in those values after 14 d and 12 d, respectively. Based on our findings, we propose that a structured-light 3D scanner can be used to obtain reliable estimates of leaf area and plant biomass.

• The Journal of Advanced Prosthodontics
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• v.5 no.4
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• pp.452-456
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• 2013

PURPOSE. The aim of this study was to evaluate the repeatability of the digitizing of silicon rubber impressions of abutment teeth by using a white light scanner and compare differences in repeatability between different abutment teeth types. MATERIALS AND METHODS. Silicon rubber impressions of a canine, premolar, and molar tooth were each digitized 8 times using a white light scanner, and 3D surface models were created using the point clouds. The size of any discrepancy between each model and the corresponding reference tooth were measured, and the distribution of these values was analyzed by an inspection software (PowerInspect 2012, Delcamplc., Birmingham, UK). Absolute values of discrepancies were analyzed by the Kruskal-Wallis test and multiple comparisons (${\alpha}$=.05). RESULTS. The discrepancy between the impressions for the canine, premolar, and molar teeth were $6.3{\mu}m$ (95% confidence interval [CI], 5.4-7.2), $6.4{\mu}m$ (95% CI, 5.3-7.6), and $8.9{\mu}m$ (95% CI, 8.2-9.5), respectively. The discrepancy of the molar tooth impression was significantly higher than that of other tooth types. The largest variation (as mean [SD]) in discrepancies was seen in the premolar tooth impression scans: $26.7{\mu}m$ (95% CI, 19.7-33.8); followed by canine and molar teeth impressions, $16.3{\mu}m$ (95% CI, 15.3- 17.3), and $14.0{\mu}m$ (95% CI, 12.3-15.7), respectively. CONCLUSION. The repeatability of the digitizing abutment teeth's silicon rubber impressions by using a white light scanner was improved compared to that with a laser scanner, showing only a low mean discrepancy between $6.3{\mu}m$ and $8.9{\mu}m$, which was in an clinically acceptable range. Premolar impression with a long and narrow shape showed a significantly larger discrepancy than canine and molar impressions. Further work is needed to increase the digitizing performance of the white light scanner for deep and slender impressions.

• Journal of Technologic Dentistry
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• v.36 no.1
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• pp.17-23
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• 2014

Purpose: The purpose of this study was to analyze and compare the relative accuracy of digitized stone models of lower full arch, using two different scanning system. Methods: Replica stone models(N=20) were produced from lower arch acrylic model. Twenty digital models were made with the white light and blue LED($Medit^{(R)}$, Korea) scanner. Two-dimensional distance between the landmarks were measured on the Delcam $CopyCAD^{(R)}$(Delcam plc, UK). Independent samples t-test was applied for comparison of the groups. All statistical analyses were performed using the SPSS software package(Statistical Package for Social Sciences for Windows, version 12.0). Results: The absolute disagreement between measurements made directly on the two different scanner-based dental digital models was 0.02~0.04mm, and was not statistically significant(P>0.05). Conclusion: The precision of the blue LED optical scanner was comparable with the digitization device, and relative accuracy was similar. However, there still is room for improvement and further standardization of dental CAD technologies.

• International Journal of Advanced Culture Technology
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• v.8 no.3
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• pp.260-268
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• 2020

Currently, it is usually a 3D scanner processing method as a laser method. However, the laser method has a disadvantage of slow scanning speed and poor precision. Although optical scanners are used as a method to compensate for these shortcomings, optical scanners are closely related to the distance and precision of the object, and have the disadvantage of being expensive. In this paper, 3D scanner using variable focus lens-based structured light module with improved measurement precision was designed to be high performance, low price, and usable in industrial fields. To this end, designed a telecentric optical system based on a variable focus lens and connected to the telecentric mechanism of the step motor and lens to adjust the focus of the variable lens. Designed a connection structure with optimized scalability of hardware circuits that configures a stepper motor to form a system with a built-in processor. In addition, by applying an algorithm that can simultaneously acquire high-resolution texture image and depth information and apply image synthesis technology and GPU-based high-speed structured light processing technology, it is also stable for changes to external light. We will designed and implemented for further improving high measurement precision.

• Journal of Technologic Dentistry
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• v.34 no.3
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• pp.213-220
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• 2012

Purpose: The aim of this study was to determine the repeatability and reproducibility of two dental scanners. Methods: The master die and the stone replicas(Kavo, Germany) were digitized in touch-probe scanner(Incise, Renishaw, UK), white light scanner(Identica, Medit, Korea) to create 3-dimensional surface-models. The number of points in the point clouds from each reading were calculated and used as the CAD reference model(CRM). Discrepancies between the points in the 3-dimensional surface models and the corresponding CRM were measured by a matching-software(Power-Inspect R2, Delcam Plc, UK). The t-student test for one samples were used for statistical analysis. Results: The reproducibility of both scanner was within $3{\mu}m$, based on mean value. The mean value between measurements made directly on the touch probe scanner digital models and those made on the white light scanner digital models was $2.20-2.90{\mu}m$, and was statistically significant(P<0.05). Conclusion: With respect to adequate data acquisition, the reproducibility of dental scanner differs. Three-dimensional analysis can be applied to differential quality analysis of the manufacturing process as well as to evaluation of different analysis methods.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1718-1720
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• 2004

This paper is focused on the improvement of reflection angle of an optical scanner by changing a shape of a torsion bar attached with an optical scanner reflector(mirror). In order to improve the light efficiency of the optical scanner by virtue of the magnetic effect, which tiny magnets are attached under both ends of the optical scanner reflector. and hence the optical scanner reflector was operated in relatively lower driving voltage. By changing the torsion bar's shape I type into S type, we've got the lower resonant frequency(32.5Hz) of an optical scanner than that of conventional one(50Hz). According to these results. The reflection angle of an optical scanner with magnets was much larger in the range of about 14.8$^{circ}$ without a magnet. By making use of a magnetic actuator instead of a conventional electrostatic actuator, the optical scanner was less influenced from outdoor dust or moisture.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.235-236
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• 2008

A configuration of illumination for high-speed color document scanner has been proposed utilizing white light emitting diode and transparent plastic lightguide. The design of illumination system including lightguide for high optical efficiency and uniform image quality is performed based on a simulation using ray-tracing method. The device characteristics are also experimentally evaluated in terms of illumination distribution against longitudinal and transverse direction on document plane. Uniform illumination distribution about 85% of in longitudinal and transverse direction is realized by control of mechanical dimension and position of lightguide.

• The Journal of Advanced Prosthodontics
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• v.8 no.3
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• pp.214-218
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• 2016

PURPOSE. We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS. To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by $10-20^{\circ}$ on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (${\alpha}=.05$). RESULTS. The differences with regard to repeatability were 4.5, 2.7, and $3.1{\mu}m$ for the canine, premolar, and molar, indicating the poorest repeatability for the canine (P<.001). For reproducibility, the differences were 6.6, 5.8, and $11.0{\mu}m$ indicating the poorest reproducibility for the molar (P=.007). CONCLUSION. Our results indicated that impressions of individual abutment teeth, digitized with a blue light scanner, had good repeatability and reproducibility.