• Imaging Science in Dentistry
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• 제47권2호
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• pp.117-122
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• 2017

Purpose: The aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement. Materials and Methods: Thirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient(ICC) was used to assess intraobserver reliability. Results: The root surface area measurements ($230.11{\pm}41.97mm^2$) obtained using CBCT were slightly greater than those ($229.31{\pm}42.46mm^2$) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT. Conclusion: This study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth.

• 원예과학기술지
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• 제16권3호
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• pp.364-365
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• 1998

본 연구는 기존 원예종에 비해 관상가치가 높은 반입종식물이 나타내는 반입현상의 다양한 변화를 측정할 수 있는 보다 정확한 검정방법을 개발코자 실시되었다. Scanning을 통한 컴퓨터 분석을 이용해 Tradescantia 2품종에 대한 전체엽면적 및 반입면적을 측정한 결과 광도가 증가할수록 전체엽면적은 감소하였으며 반입면적은 증가하는 결과를 나타내었다. 음지에서는 공시된 2품종 모두의 엽면적은 증가하였으며 반입면적은 급속히 감소하였다. 또한 위에 언급한 방법과 동일한 수법으로 광도에 따른 반입색차를 측정한 결과 양지에서 가장 밝은 엽색정도를 보였으며 광도가 감소할수록 엽색정도가 짙어졌다. 위의 결과에 대해 엽면적계로 전체 엽면적 및 반입면적을 측정한 값($cm^2$)과 본 연구에서 scanning을 하여 얻은 그래픽파일을 이용한 컴퓨터 분석시의 수치(pixel)간의 상관정도를 구한 결과 매우 높은 상관관계가 있었다. 따라서 컴퓨터그래픽분석을 이용한 엽면적 및 반입면적의 측정법은 매우 정확하며 간편하게 쓰일 수 있을 것으로 추측되었다.

• 대한방사선기술학회지:방사선기술과학
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• 제8권2호
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• pp.29-45
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• 1985

Computed Tomography Scanner (CT) is highly expensive in operation as well as purchasing. That reason may cause not only to increase the burden of patients but also to waste the capital resources leading to financial difficulties. However the numbers of CT installed throughout the country is increasing, because of efficiency in medical care, patient's concern, competitions among the hospitals within the same area. In the non-Metropolitan area the scanners were expected to be less utilized and less profitable. Nine hospitals equipped with the CT were studied on the utilization of that equipment during the period from November 1984 to February 1985 in non-Metropolitan area and break-even point in one hospital was analyzed for estimating profitabilities. The results were as follows ; 1. Among those nine hospitals, four hospitals had less than 400 beds, which is one of the restrictive minimum standards on the installation of Whole-body Computed Tomography Scanner. 2. The operating time during the normal operation period was longer than those of any other studies, but the accumulated down time was also longer than those of any other studies. The average number of scanning per week for each CT was 45, while the estimated number of for the break-even point was 56.7 cases. 3. When the downtime was excluded in calculating the average operation would be much closer to the cases for the break-even point. Therefore the break-down of the equipment was to be a main cause of the low profitability. 4. The average scanning rate for head area was 33.6%, however three of the nine hospitals showed about 20%. 5. If scanning ratio for the body parts excepting head was increased, the number of scanning for the break-even point would be diminished. 6. The small size hospital especially located near the Metropolitan area showed largest loss in the CT operation. In purchasing the highly expensive equipments in hospitals, demand should be taken into account and planning is recommended.

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 1975년도 제14차 학술대회
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• pp.79.1-79.1
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• 1975

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 춘계학술발표회논문집
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• pp.15-26
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• 2004

The calibration for systematic error in LiDAR is crucial for the accuracy of airborne laser scanning. The main error is the misalignment of platforms between INS(Inertial Navigation System) and Laser scanner For planimetrical calibration of LiDAR, the building is good feature which has great changes in height and continuous flat area in the top. The planimetry error(pitch, roll) is corrected by adjustment of height which is calculated from comparing ground control points(GCP) of building to laser scanning data. We can know scale correction of laser range by the comparison of LiDAR data and GCP is arranged at the end of scan angle where maximize the height error. The area for scale calibration have to be large flat and have almost same elevation. At 1000m for average flying height, The Accuracy of laser scanning data using LiDAR is within 110cm in height and ${\pm}$50cm in planmetry so we can use laser scanning data for generating 3D terrain surface, expecically digital surface model(DSM) which is difficult to measure by aerial photogrammetry in forest, coast, urban area of high buildings

• 한국CDE학회논문집
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• 제4권1호
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• pp.60-68
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• 1999

In reverse engineering (RE) sustems, the quality of the data aquisition process is crucial to the accuracy of the reverse engineered three dimensional computer-aided design (CAD) model. However, these tasks are predominantly done manually, and little work has been done to improve the efficiency of scanning by determining the minimum number of scans and the optimal scanning directions. In this paper, new scanning and registration methods using tooling balls are developed to assist in determining the optimal parameter for these processes. When the object to scanned has no concavity, attaching path of the object and its bounding rectangle are used for optimal scanning and registration. Then minimum number of tooling balls and their positions are calculated automatically. In the case of concave parts, the scanning plan should include a complete scan of the concave area. With the surface normal vector and the scanning direction, the minimum degree of rotating the part can be calculated. But the maximum rotation should be restricted in order to prevent occlusion of the part. Finally tow sample part ar scanned based on the proposed methods and the results are discussed.

• 로봇학회논문지
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• 제15권4호
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• pp.341-349
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• 2020

Recently, interest in ground subsidence in urban areas has increased after a large sinkhole occurred near the high-story building area in Jamsil, Seoul, Korea, in 2014. If a massive sinkhole occurs in an urban area, it is crucial to assess its risk rapidly. Access to humans for on-site safety diagnosis may be difficult because of the additional risk of collapse in the disaster area. Generally, inspection using drones equipped with high-speed lidar sensors can be utilized. However, if the sinkhole is created vertically to a depth of 100 m, similar to the sinkhole in Guatemala, the drone cannot be applied because of the wireless communication limit and turbulence inside the sinkhole. In this study, a three-dimensional (3D) scanning system was fabricated and operated using a towed cable in a massive vertical sinkhole to a depth of 200 m. A high-speed lidar sensor was used to obtain a continuous cross-sectional shape at a certain depth. An inertial-measuring unit was applied to compensate for the error owing to the rotation and pendulum movement of the measuring unit. A reconstruction algorithm, including the compensation scheme, was developed. In a vertical hole with a depth of 180 m in the mining area, the fabricated system was applied to scan 0-165 m depth. The reconstructed shape was depicted in a 3D graph.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.773-780
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• 2003

The characteristics of soft clays is very important for the land development plan. This study is to investigate correlations between the engineering properties and the characteristics of clay minerals of the disturbed clay samples obtained from Sihwa area. This study included X-Ray Diffraction Analysis, X-Ray Fluorescence Spectrometer Analysis, Scanning Electron Microscopy Analysis and Energy Dispersive X-Ray Spectrometer Analysis. The correlations between the clay mineral properties and the laboratory and field testing results were investigated.

• The Journal of Advanced Prosthodontics
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• 제13권4호
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• pp.191-204
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• 2021

PURPOSE. The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo. MATERIALS AND METHODS. A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles. Then, 10 scans were taken by an IOS with the gauge in the patient's mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150 angles were measured and compared with the gauge's reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS. Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018 ± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION. Currently, there is no standardized procedure to assess the accuracy of IOS in vivo, and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area.

• Journal of Korean Vacuum Science & Technology
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• 제4권4호
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• pp.102-106
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• 2000

We report scanning force microscope (SFM) observations of enhanced calcite dissolution in aqueous solution due to mechanical stimulation induced by the SFM tip. Images and mechanical treatment were performed in saturated ($\geq$ 60 ${\mu}{\textrm}{m}$) CaCO$_3$ solution adjusted to pH~9. Small area scans of monolayer steps significantly increased the step velocity in the scanned area (in the direction corresponding to dissolution) when the applied contact force is above about 160 nN fer the tips employed. The step velocity could be increased at least an order of magnitude by scanning at even higher contact forces (e.g.,270nN). This enhancement is a function of step orientation relative to the calcite lattice. Indentations near preexisting steps also locally enhance the step velocity. We present evidence that the higher dissolution rates are caused by stress-induced increases in the rate of double-kink nucleation.