• Imaging Science in Dentistry
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• v.46 no.2
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• pp.93-101
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• 2016

Purpose: The objective of this study was to investigate the effect of varying resolutions of cone-beam computed tomography images on the accuracy of linear measurements of edentulous areas in human cadaver heads. Intact cadaver heads were used to simulate a clinical situation. Materials and Methods: Fiduciary markers were placed in the edentulous areas of 4 intact embalmed cadaver heads. The heads were scanned with two different CBCT units using a large field of view ($13cm{\times}16cm$) and small field of view ($5cm{\times}8cm$) at varying voxel sizes (0.3 mm, 0.2 mm, and 0.16 mm). The ground truth was established with digital caliper measurements. The imaging measurements were then compared with caliper measurements to determine accuracy. Results: The Wilcoxon signed rank test revealed no statistically significant difference between the medians of the physical measurements obtained with calipers and the medians of the CBCT measurements. A comparison of accuracy among the different imaging protocols revealed no significant differences as determined by the Friedman test. The intraclass correlation coefficient was 0.961, indicating excellent reproducibility. Inter-observer variability was determined graphically with a Bland-Altman plot and by calculating the intraclass correlation coefficient. The Bland-Altman plot indicated very good reproducibility for smaller measurements but larger discrepancies with larger measurements. Conclusion: The CBCT-based linear measurements in the edentulous sites using different voxel sizes and FOVs are accurate compared with the direct caliper measurements of these sites. Higher resolution CBCT images with smaller voxel size did not result in greater accuracy of the linear measurements.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.261-269
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• 1998

With the CT findings as gold standard, the sensitivity, the specificity, and the diagnostic accuracy of Waters' radiography and Waters' radiography with panoramic radiography were compared in the diagnosis of antral mucosal thickening of 16 patients. Three oral radiologists and three non-oral radiologists interpreted the Waters' radiographs and after 4 weeks, interpreted the Waters' radiographs and panoramic radiographs simultaneously. The interpretation point was the existence or the non-existence of the mucosal thickening on the medial, the posterolateral, the floor, and the roof of maxillary sinus. The obtained results were as followed : 1. In oral radiologist group, the sensitivity, specificity and diagnostic accuracy of Waters' film were 0.7250, 0.8489 and 0.7578 respectively. 2. The sensitivity and the diagnostic accuracy in oral radiologist group were higher than those of non-oral radiologist group (P<0.05), but there was no significant difference between two groups in the specificity (P>0.05), 3. There was no significant difference of the diagnostic abilities except the specificity in oral radiologist group between Waters' radiography and Waters' radiography with panoramic radiography (P>0.05). 4. The sensitivity and the diagnostic accuracy were the highest in the case of medial wall interpretation, the specificity was the highest in the posterolateral wall. 5. In the posterolateral wall and the floor, the sensitivity and the diagnostic accuracy of oral radiologist group were higher than those of non-oral radiologist group (P<0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.3
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• pp.342-350
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• 2003

Statement of problem. Titanium-Nickel alloy might be used in various prosthetic restorations since it has a unique property such as super-elasticity and high fatigue resistance. However, little is known about the casting ability of this alloy. Purpose. This in vitro study compared the casting accuracy and the porosity made with different investments and various sprue designs to ascertain what casting condition would be better for the fabrication of Ti-Ni cast restorations. Material and methods. A total of 70 Ti-Ni alloy crowns were made and divided into 7 groups of 10 copings on a metal master die. For measuring the effect of the sprue numbers, two groups with one and two 8-gauge sprues were compared. Moreover, the results of the conventional sprue and the double thickness sprues were compared. Three investments were used; carbon free phosphate bonded investment, titanium investment and gypsum bonded investment. The cast restorations were evaluated at 48 points on the entire circumferential margin with a stereomicroscope measuring in micrometers. Each crown was radiographically examined for casting defects and porosity. Data on casting accuracy were analyzed using two-way and Post hoc Scheffe's comparison to determine whether significant differences existed at the 95% confidence level. Student-Newman-Keuls test were performed to identify significant differences in the number of voids. Results. The double sprueing group and double thickness group had significantly less marginal discrepancy than the single sprueing group (P<.05 and P<.01, respectively). The castings with phosphate bonded investment showed the least marginal discrepancy and the smoothest surface. The castings invested in the gypsum bonded investment had the greatest gaps in margin and the largest failure rate. The double sprueing group and phosphate bonded investment group had significantly smaller void numbers and smaller void size than the other groups. Conclusion. Within the limitations of this in vitro study, the casting accuracy of the groups using thicker, double sprue design and the phosphate bonded investment was significantly superior. Moreover, void number and size were less than other groups.

• The Korean Journal of Cytopathology
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• v.4 no.1
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• pp.1-8
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• 1993

This study was performed in order to evaluate the accuracy and the usefulness of the fine needle aspiration cytology (FNAC) on the breast lesions, to compare the FNAC findings between fibroadenoma and fibrocystic disease, and to determine the accuracy of cytologic Black's nuclear grading. The subjects in this study were 110 cases of FNAC, later confirmed by biopsy, between January 1988 and December 1991. The results are as follows ; 1 Comparison between the results of the FNAC and the histologic findings revealed that FNAC had a sensitivity of 96.6%, a specificity of 100%, a false negative rate of 3.4% a false positive rate of 0.0%, and an overall diagnostic accuracy of 98.2%. 2 Semi-quantitative evaluation of epithelial celluarity, stroma, and naked nuclei in the smears of aspirate showed high celluarity in 56.7% of the aspirates from fibroadenoma and in 0% of those from fibrocystic disease. Abundant stroma was found in 46.7% of the fibroadenoma and none of fibrocystic disease. Numerous naked nuclei were found in 60% of the fibroadenoma and 4.5% of the fibrocystic disease. The overall diagnostic accuracy was 98% 3. In order to determine the accuracy of Black's nuclear grading of FNAC on breast carcinoma, we retrospectively studied 38 cases of ductal carcinomas diagnosed by FNAC with subsequent histologic confirmation. The concordance rate with histology was 94.7%. These results suggest that FNAC of breast is a diagnostically accurate method, and provide for the preoperative differential diagnosis between fibroadenoma and fibrocystic disease. Our results also suggest that the evaluation of nuclear grading of FNAC can predict clinical outcome and decide the way of management of breast cancer.

• Archives of Plastic Surgery
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• v.37 no.6
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• pp.758-762
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• 2010

Purpose: It is difficult to provide accurate diagnosis and proper treatment for vascular anomalies, because vascular anomalies have a wide spectrum of lesion with various symptoms. Furthermore, vascular anomalies often require the services of a wide range of specialists. So, many patients have been discouraged by the lack of expertise and treatment options available to them. In this study, we aimed to describe the scope of the Vascular Malformation clinic (VAM clinic), a multidisciplinary clinic for hemangioma and vascular malformation patients and investigate of diagnostic accuracy of VAM clinic. Methods: 68 patients have included in a retrospective, medical record review study in the VAM clinic from may 2002 to august 2009. Data included the types of diagnoses of patients seen in the clinic, locations of lesions, comparison of accuracy of diagnoses at other clinic and initial diagnoses at VAM clinic and types of recommended treatments. Results: Initial diagnosis at VAM clinic showed 94.2% accuracy, while diagnosis at other clinic only showed 12.5% accuracy. Head and neck is most frequently occurred lesions in patients of VAM clinic. And VAM clinic is able to provide various and proper treatments to patients. Conclusion: Hemangiomas and vascular malformations can present with various medical problems. VAM clinic, the multidisciplinary clinic provided accurate diagnoses and proper treatments to patients.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.1
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• pp.8-14
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• 2020

The human impact of particulate matter are revealed and demand for improved forecast accuracy is increasing. Recently, efforts is made to improve the accuracy of PM10 predictions by using machine learning, but prediction performance is decreasing due to the particulate matter data with a large rate of low concentration occurrence. In this paper, separation prediction model by concentration is proposed to improve the accuracy of PM10 particulate matter forecast. The low and high concentration prediction model was designed using the weather and air pollution factors in Cheonan, and the performance comparison with the prediction models was performed. As a result of experiments with RMSE, MAPE, correlation coefficient, and AQI accuracy, it was confirmed that the predictive performance was improved, and that 20.62% of the AQI high-concentration prediction performance was improved.

• The Journal of Advanced Prosthodontics
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• v.14 no.2
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• pp.88-95
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• 2022

PURPOSE. This study investigated the accuracy of full-arch intraoral scans obtained by various scan strategies with the segmental scan and merge methods. MATERIALS AND METHODS. Seventy intraoral scans (seven scans per group) were performed using 10 scan strategies that differed in the segmental scan (1, 2, or 3 segments) and the scanning motion (straight, zigzag, or combined). The three-dimensional (3D) geometric accuracy of scan images was evaluated by comparison with a reference image in an image analysis software program, in terms of the arch shape discrepancies. Measurement parameters were the intermolar distance, interpremolar distance, anteroposterior distance, and global surface deviation. One-way analysis of variance and Tukey honestly significance difference post hoc tests were carried out to compare differences among the scan strategy groups (α = .05). RESULTS. The linear discrepancy values of intraoral scans were not different among scan strategies performed with the single scan and segmental scan methods. In general, differences in the scan motion did not show different accuracies, except for the intermolar distance measured under the scan conditions of a 3-segmental scan and zigzag motion. The global surface deviations were not different among all scan strategies. CONCLUSION. The segmental scan and merge methods using two scan parts appear to be reliable as an alternative to the single scan method for full-arch intraoral scans. When three segmental scans are involved, the accuracy of complete arch scan can be negatively affected.

• Journal of Radiation Protection and Research
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• v.46 no.4
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• pp.204-212
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• 2021

Background: Identification of radioisotopes for plastic scintillation detectors is challenging because their spectra have poor energy resolutions and lack photo peaks. To overcome this weakness, many researchers have conducted radioisotope identification studies using machine learning algorithms; however, the effect of data normalization on radioisotope identification has not been addressed yet. Furthermore, studies on machine learning-based radioisotope identifiers for plastic scintillation detectors are limited. Materials and Methods: In this study, machine learning-based radioisotope identifiers were implemented, and their performances according to data normalization methods were compared. Eight classes of radioisotopes consisting of combinations of ²²Na, ⁶⁰Co, and ¹³⁷Cs, and the background, were defined. The training set was generated by the random sampling technique based on probabilistic density functions acquired by experiments and simulations, and test set was acquired by experiments. Support vector machine (SVM), artificial neural network (ANN), and convolutional neural network (CNN) were implemented as radioisotope identifiers with six data normalization methods, and trained using the generated training set. Results and Discussion: The implemented identifiers were evaluated by test sets acquired by experiments with and without gain shifts to confirm the robustness of the identifiers against the gain shift effect. Among the three machine learning-based radioisotope identifiers, prediction accuracy followed the order SVM > ANN > CNN, while the training time followed the order SVM > ANN > CNN. Conclusion: The prediction accuracy for the combined test sets was highest with the SVM. The CNN exhibited a minimum variation in prediction accuracy for each class, even though it had the lowest prediction accuracy for the combined test sets among three identifiers. The SVM exhibited the highest prediction accuracy for the combined test sets, and its training time was the shortest among three identifiers.

• Structural Engineering and Mechanics
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• v.85 no.4
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• pp.485-500
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• 2023

The non-linear static analysis of reinforced concrete (RC) structures using the three-dimensional (3D) finite element method is a time-consuming and challenging task. Moreover, this type of analysis encounters numerical problems such as the lack of convergence of results in the stages of growth and propagation of cracks in the structure. The time integration analysis along with the mass scaling (MS) technique is usually used to overcome these limitations. Despite the use of this method in the 3D finite element analysis of RC structures, a comprehensive study has not been conducted so far to assess the effects of the MS method on the accuracy of results. This study aims to evaluate the accuracy of the MS method in the non-linear quasi-static finite element analysis of RC structures. To this aim, different types of RC structures were simulated using the finite element approach based on the implicit time integration method and the mass scaling technique. The influences of effective parameters of the MS method (i.e., the allowable values of increase in the mass of the RC structure, the relationship between the duration of the applied load and fundamental vibration period of the RC structure, and the pattern of applied loads) on the accuracy of the simulated results were investigated. The accuracy of numerical simulation results has been evaluated through comparison with existing experimental data. The results of this study show that the achievement of accurate structural responses in the implicit time integration analyses using the MS method involves the appropriate selection of the effective parameters of the MS method.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.9 no.1
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• pp.101-112
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• 2002

Purpose: This study evaluated the accuracy of electronic devices compared with mercury sphygmomanometer. Of 132 outpatients with electronic devices. 77 who possessed oscillometric cuff devices participated in this study. Method: When the blood pressure was measured, all electronic devices were connected by means of a Y-connector to a mercury sphygmomanometer. Using the simultaneous same arm approach, each comparison was carried out three times at 2-minute intervals. Results: Compared with the mercury sphygmomanometer, the electronic devices underestimated systolic and diastolic blood pressure, respectively by $4.0{\pm}5.8mmHg$ and $2.5{\pm}67mmHg$, which satisfies the standard error range of the American Association for the Advancement of Medical Instrumentation. According to the British Hypertension Society criteria, these differences achieved C grade for both systolic and diastolic pressure. For the graphical analysis, the differences had a tendency to fulfill the permitted error limits in both diastolic and systolic blood pressure. Moreover, the purchase duration was not correlated with the accuracy of electronic devices. Conclusion: These results indicate that difference in blood pressure between electronic devices and mercury sphygmomanometer is within the standard error. Therefore, electronic blood pressure measuring devices may be useful for therapeutic self-management of hypertension.