• Journal of Technologic Dentistry
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• v.45 no.1
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• pp.1-7
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• 2023

Purpose: To evaluate the marginal and internal fit of metal coping fabricated by a metal three-dimensional (3D) printer that uses selective laser melting (SLM). Methods: An extraoral scanner was used to scan a die of the prepared maxillary right first molar, and the coping was designed using computer-aided design software and saved as an stereo lithography (STL) file. Ten specimens were printed with an SLM-type metal 3D printer (SLM group), and 10 more specimens were fabricated by casting the castable patterns output generated by a digital light processing-type resin 3D printer (casting the 3D printed resin patterns [CRP] group). The fit was measured using the silicon replica technique, and 8 points (A to H) were set per specimen to measure the marginal (points A, H) and internal (points B~G) gaps. The differences among the groups were compared using the Mann-Whitney U-test (α=0.05). Results: The mean of marginal fit in the SLM group was 69.67±18.04 ㎛, while in the CRP group was 117.10±41.95 ㎛. The internal fit of the SLM group was 95.18±41.20 ㎛, and that of the CRP group was 86.35±32 ㎛. As a result of statistical analysis, there was a significant difference in marginal fit between the SLM and CRP groups (p<0.05); however, there was no significant difference in internal fit between the SLM group and the CRP group (p>0.05). Conclusion: The marginal and internal fit of SLM is within the clinically acceptable range, and it seems to be applicable in terms of fit.

• Journal of Biomedical Engineering Research
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• v.30 no.4
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• pp.333-340
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• 2009

MR compatible coaxial-slot antenna for microwave hyperthermia was developed while its structure and size of each part were determined by computer simulation using finite element method(FEM). Its local heating performance was evaluated using tissue-mimic phantom and swine muscles. 2% agarose gel mixed with 6mM/$\ell$ $MnCl_2$ as a biological tissue-mimic phantom was heated by the proposed antenna driven by a 2.45GHz microwave generator. The temperature changes of the phantom were monitored using multi-channel digital thermometer at the distance of 0mm, 5mm, 10mm and 20mm from the tip center of the antenna. Also muscle tissue of swine was heated for 2 and 5minutes with 50W and 30W of microwave generator powers, respectively, to evaluate the local heating performance of the antenna. MRI compatibility was also verified by acquiring MR images and MR temperature map. MR signals were acquired from the agarose gel phantom using $T2^*$ GRE sequence with 1.5T clinical MRI scanner(Signa Echospeed, GE, Milwaukee, WI, U.S.A.) at Pusan Paik Hospital and were transferred to PC in order to reconstruct MR images and temperature map using proton resonance frequency(PRF) method and laboratory-developed phase unwrapping algorithm. Authors found that it has no severe distortion due to the antenna inserted into the phantom. Finally, we can conclude that the suggested coaxial-slot antenna has an excellent local heating performance for both of tissue-mimic phantom and swine muscle, and it is compatible to 1.5T MRI scanner.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1324-1333
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• 2010

This paper is used in a recent civil engineering field in three-dimensional laser-meter tiles using thermal imaging cameras for the weathered rock slopes precisely measured indirectly, to the degree that began in the will. In the field is difficult to access the degree of weathering of the rock slope to the existing direct way to compensate for the shortcomings of 3D Terrestrial Laser Scanner and weathering characteristics of rocks using thermal imaging cameras to get the information to analyze the degree of rock weathering is. Intensity of 3D TLS and the thermal camera with image analysis to analyze the degree of weathering of bedrock in the field of core drilling targeting indoor laboratory tests were analyzed through the study. Granite, gneiss, sandstone, much of the cancerous samples, each experiment has a 40 per category, each of which 30 were used to analyze the data collected. That degree of rock weathering, the rock, depending on the strength of the Intensity values can change, depending on the level of thermal imaging camera, also weathered the changes in temperature could see. Intensity is the strength of weak rocks, the more value decrease, the temperature of the thermal imaging camera through the swell Intensity and notice that the temperature had an inverse relationship. Intensity value of the low strength of weak rock, but the value came out of the rocks have been proved to be largely dependent on the contrast. The contrast of the surface rocks are weathered dark Intensity values lower temperature to swell the contrary, the degree of weathering can be distinguished.

• The Journal of the Korean dental association
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• v.50 no.3
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• pp.110-117
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• 2012

Dental computer-aided design (CAD) and computer-aided manufacturing (CAM) technology have rapidly progressed over the past 30 years. The technology, which can be used in the dental laboratory, the dental office and the form of production centers, has become more common in recent years. This technology is now applied to inlays, onlays, crowns, fixed partial dentures, removable partial denture frameworks, complete dentures, templates for implant installation, implant abutments, and even maxillofacial prostheses. Dentists and dental technicians, who want to use these techniques, should have certain basic knowledge about that. This article gives an overview of CAD/CAM technologies, histories and how it applies in prosthetic dentistry.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.5
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• pp.237-242
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• 2006

Knowledge of molecular mechanisms governing malignant transformation brings new opportunities for therapeutic intervention against cancer using novel approaches. One of them is gene therapy based on the transfer of genetic material to an organism with the aim of correcting a disease. The application of gene therapy to the cancer treatment has led to the development of new experimental approaches such as suicidal gene therapy, inhibition of oncogenes and restoration of tumor-suppressor genes. Suicidal gene therapy is based on the expression in tumor cells of a gene encoding an enzyme that converts a prodrug into a toxic product. Representative suicidal genes are Herpes simplex virus type 1 thymidine kinase (HSV1-tk) and cytosine deaminase (CD). Especially, physicians and scientists of nuclear medicine field take an interest In suicidal gene therapy because they can monitor the location and magnitude, and duration of expression of HSV1-tk and CD by PET scanner.

• ETRI Journal
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• v.41 no.6
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• pp.782-796
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• 2019

This paper presents a hierarchical framework for managing the sampling distribution of a particle filter (PF) that estimates the global positions of mobile robots in a large-scale area. The key concept is to gradually improve the accuracy of the global localization by fusing sensor information with different characteristics. The sensor observations are the received signal strength indications (RSSIs) of Wi-Fi devices as network facilities and the range of a laser scanner. First, the RSSI data used for determining certain global areas within which the robot is located are represented as RSSI bins. In addition, the results of the RSSI bins contain the uncertainty of localization, which is utilized for calculating the optimal sampling size of the PF to cover the regions of the RSSI bins. The range data are then used to estimate the precise position of the robot in the regions of the RSSI bins using the core process of the PF. The experimental results demonstrate superior performance compared with other approaches in terms of the success rate of the global localization and the amount of computation for managing the optimal sampling size.

• Journal of Technologic Dentistry
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• v.44 no.2
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• pp.31-37
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• 2022

Purpose: The aim of this study was to evaluate the accuracy of provisional crowns manufactured using a milling machine and a digital light processing (DLP) printer. Methods: A full-contour crown was designed using computer-aided design software. Provisional crowns of this design were manufactured using a milling machine and using a DLP three-dimensional (3D) printer (N=20). The provisional crowns were digitized with an extraoral scanner, and 3D deviation analysis was applied to the scanned data to confirm their accuracy. An independent t-test was performed to detect the significant differences, and the Kolmogorov-Smirnov test was used for analysis (α=0.05). Results: No significant differences were found among the precision of marginal surface between the printed and milled crowns (p=0.181). The trueness of marginal and internal surfaces of the milled crowns were statistically higher than those of the printed crowns (p=0.024, p=0.001; respectively). Conclusion: The accuracy of provisional crowns manufactured using a milling machine and a 3D printer differed significantly except with regards to the precision of the internal surface. However, all the crowns were clinically acceptable, regardless of the manufacturing method used.

• Journal of Technologic Dentistry
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• v.46 no.1
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• pp.1-7
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• 2024

Purpose: The goal of this study was to determine the clinical acceptability of various cement space settings for the marginal and internal fit of a zirconia core manufactured using additive manufacturing. Methods: The maxillary right incisor served as the master model. After scanning the maxillary right incisor with a dental 3D (three-dimensional) scanner, the stereo lithography file was created using different cement space settings of 40, 120, and 200 ㎛ using computer-aided design software (Dental System 2018; 3Shape). The marginal and internal fit of the 3 groups were determined using the silicon replica technique. Measurement points were divided into the following three categories: margin, axial wall, and incisal. To ensure more accurate measurements, these three measurement points were divided into 8 points. The Shapiro-Wilk, one-way ANOVA, and Tukey's honestly significant difference test (for all tests α=0.05) were the statistical analyses that were included in the study. Results: The CS (cement space)-200 group had better marginal and internal fit than the CS-40 and CS-120 groups, and there were statistically significant differences at the marginal and incisal points, except for the axial wall points. CS-200 group, both marginal and internal fit were within 120 ㎛, which is the clinically acceptable value. Conclusion: This study suggests that a 200 ㎛ cement space setting is ideal for optimal marginal and internal fit of 3D-printed ceramic crowns.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.693-700
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• 2020

This study compared the accuracy and reliability of definitive casts fabricated from a digital impression and conventional impression technique. A master model with the prepared upper full-arch tooth was used. Samples of ten plaster models and ten polyurethane models were duplicated using a selected standard master model. Six linear measurements were recorded between the landmarks, directly on each of the stone models and the polyurethane models on two occasions by a double examiner. The Wilcoxon signed-rank test, interclass correlation coefficient (ICC), measurement error (MSE), and limit of agreement (LoA) were used for statistical analysis. The ICC ranged from 0.76 to 0.99 when comparing the stone models and polyurethane models. The mean difference between the stone models and polyurethane models ranged from 0.09mm to 0.20mm, suggesting that stone models might be slightly larger than polyurethane models. Based on this study, the accuracy of the polyurethane models in evaluating the performance of an oral scanner and subtractive technology was acceptable. Further studies will be needed on patient subjects under clinical conditions that may involve missing or malpositioned teeth and fixed dental prostheses because this study was limited to use a standard master model and duplicated sample models in a laboratory setting.

• Tuberculosis and Respiratory Diseases
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• v.42 no.6
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• pp.813-822
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• 1995

Background: Bronchial hyperresponsiveness and abnormal response such as a loss of distensibility are pathophysiologic characteristics if bronchial asthma. The only means of direct in vivo measurement of airway size had been a tantalium bronchography, until high-resolution computed tomography(HRCT) enabled to measure noninvasively two dimensional airway area more accurately and reliably. Method: To investigate airway area responses to bronchial provocation with methacholine and evaluate the major sites of bronchial constriction in patients with bronchial asthma. We examined HRCT scans in five patients with bronchial asthma who had significant bronchoconstriction(20% or more decrease in $FEV_1$) using CT scanner(5,000T CT, Shimadzu Co, Japan) before and in 3~5 min. after methacholine inhalation. Airways which were matched by parenchymal anatomic landmarks in each patient before and after methacholine inhalation were measured using film scanner(TZ-3X scanner; Truvel Co. Chatsworth CA, USA) and a semiautomated region growing method. Results: 1) We identified 9 to 12 airways in each patient which were matched by parenchymal anatomic landmarks before and after methacholine inhalation. 2) Airway responses to methacholine are quite different even in a patient. 3) The constriction of small airways(average diameter <2 mm; area < $3.14mm^2$) was 48.7%(8.3; SEM, n=43), being more prominant than that of large airways(average diameter >2 mm; area > $3.14mm^2$), 53.8% (4.4;SEM, n=10), but not significantly different(p>0.05). 4) There was no significant difference in the degree of constriction between upper(44.3% +5.8; mean + SEM, n=30) and lower lung regions(56.7% +4.5, n=23). Conclusions: Thus airway responses to methacholine bronchoprovocation is quite variable in a patient with bronchial asthma and has no typical pattern in patients with bronchial asthma.