• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.139-145
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• 2012

The purpose of this study was to evaluate the accuracy of Root ZX and Sybron Mini in determining the working length using 2.5% Sodium Hypochlorite, 2% Chlorhexidine gel and saline. Donnelly's gelatin technique was used for measuring twenty extracted human teeth. Electronic working length was measured at the display 0.5 and 0.0 level of each electronic apex locator using a digital caliper to the nearest 0.01 mm. Each measurement was repeated for each different irrigants. Accuracy of Sybron Mini was not significantly different from the Root ZX in the three different irrigants, and there was no significant difference in the accuracy of electronic apex locators among the irrigants when used as recommended by manufacturer (measuring electronic working length at 0.0 level of Sybron Mini and at 0.5 level of Root ZX).

• Imaging Science in Dentistry
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• v.51 no.4
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• pp.429-438
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• 2021

Purpose: This study investigated the accuracy of laser-scanned models and 3-dimensional(3D) rendered cone-beam computed tomography (CBCT) compared to the gold standard (plaster casts) for linear measurements on dental arches. Materials and Methods: CBCT scans and plaster models from 30 patients were retrieved. Plaster models were scanned by an Emerald laser scanner (Planmeca, Helsinki, Finland). Sixteen different measurements, encompassing the mesiodistal width of teeth and both arches' length and width, were calculated using various landmarks. Linear measurements were made on laser-scanned models using Autodesk Meshmixer software v. 3.0 (Autodesk, Mill Valley, CA, USA), on 3D-rendered CBCT models using OnDemand 3D v. 1.0 (Cybermed, Seoul, Korea) and on plaster casts by a digital caliper. Descriptive statistics, the paired t-test, and intra- and inter-class correlation coefficients were used to analyze the data. Results: There were statistically significant differences between some measurements on plaster casts and laser-scanned or 3D-rendered CBCT models (P<0.05). Molar mesiodistal width and mandibular anterior arch width deviated significantly different from the gold standard in both methods. The largest mean differences of laser-scanned and 3D-rendered CBCT models compared to the gold standard were 0.12±0.23 mm and 0.42±0.53 mm, respectively. Most of the mean differences were not clinically significant. The intra- and inter-class correlation results were acceptable for all measurements(>0.830) and between observers(>0.801). Conclusion: The 3D-rendered CBCT images and laser-scanned models were useful and accurate alternatives to conventional plaster models. They could be used for clinical purposes in orthodontics and prostheses.

• Journal of Practical Engineering Education
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• v.16 no.2
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• pp.159-165
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• 2024

This study investigates the comprehensive system for collecting intelligent learning activity data tailored to learner-centered personalized education. We compared and analyzed the characteristics of xAPI, Caliper analytics, and cmi5, which are learning activity data collection standards, and established a system that allows not only standardized data but also non-standardized learning activity data to be stored as big data for artificial intelligence learning analysis. As a result, the system was structured into five stages: defining data types, standardizing learning data using xAPI, storing big data, conducting learning analysis (statistical and AI-based), and providing learner-tailored services. The aim was to establish a foundation for analyzing learning data using artificial intelligence technology. In future research, we will divide the entire system into three stages, implement and execute it, and correct and supplement any shortcomings in the design.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.1042-1048
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• 2008

Disc brake noise is an important customer satisfaction and warranty issue for many manufacturers as indicated by technical literature regarding the subject coming from Motor Company. This research describes results of a study to assess disk brake squeal propensity using finite element methods and optimal technique (Kriging). In this study, finite element analysis has been performed to determine likely modes of brake squeal. This paper deals with friction-induced vibration of disc brake system under contact friction coefficient. A linear, finite element model to represent the floating caliper disc brake system is proposed. The complex eigen-values are used to investigate the dynamic stability and in order to verify simulations which are based on the FEM model. In this paper, Kriging from among the meta-modeling techniques is proposed for an optimal design scheme to reduce the brake squeal noise.

• Archives of Craniofacial Surgery
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• v.21 no.2
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• pp.80-86
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• 2020

Positional plagiocephaly is increasing in infants. Positional plagiocephaly is an asymmetric deformation of skull due to various reasons; first birth, assisted labor, multiple pregnancy, prematurity, congenital muscular torticollis and position of head. Positional plagiocephaly can mostly be diagnosed clinically and by physical examinations. The simplest way to assess the severity of plagiocephaly is to use a diagonal caliper during physical examination, which measures the difference between the diagonal lengths on each side of the head. Plagiocephaly can be treated surgically or conservatively. Positional plagiocephaly, which is not accompanied by craniosynostosis, is treated conservatively. Conservative treatments involve a variety of treatments, such as change of positions, physiotherapy, massage therapy, and helmet therapy. Systematic approaches to clinical examination, diagnosis and treatment of positional plagiocephaly can be necessary and the age-appropriate treatment is recommended for patients with positional plagiocephaly.

• Imaging Science in Dentistry
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• v.35 no.3
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• pp.115-119
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• 2005

Purpose : To evaluate the magnification error percentage in repeatedly taken panoramic radiographs of same patient and machine. Materials and Methods : 92 panoramic radiographs from 46 patients were traced and 30 horizontal and vertical measurements were made with digital sliding caliper. The results were compared with paired t-test. Results : There was no statistically significant difference between the two measurements. The overall difference as percentage error was $6.19\pm5.60\%$. The largest error as $14.61\pm12.44\%$ was found at condylar height 1, and smallest as $1.86\pm1.61\%$ at mandibular height. Overall vertical error excluding condylar height 1 was $3.76\pm3.97\%$, and the horizontal error $6.88\pm5.92\%$. Conclusion . Repeatedly taken panoramic radiographs of the same patient and machine was reliable since there was no significant percentage error difference but the percentage error ranged from $1.86\pm1.61\%\;to\;14.61\pm12.44\%$ indicating the error depends on the measuring site.

• The Journal of Korean Academy of Prosthodontics
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• v.11 no.1
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• pp.9-14
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• 1971

The author measured the maximum interincisal distance by means of the sliding caliper. The subjects measured here were 149 healthy Korean males and 229 females, ranging from 15 to 49 years old, with normal occlusion. The results were as follows; 1. The mean value of maximum interincisal distance was $50.03{\pm}0.22mm$. in male and $45.18{\pm}0.14mm$. in female. 2. There was a significant difference in the mean value between male female. 3. The interincisal distances in maximum opening were slightly larger in male than female. 4. There was no significant difference in the mean value between the age groups in Korean adults. But it has been revealed that there was apparent difference in the mean value between 15~19 years and 20~29 years old, in female. 5. It has been appeared that maximum interincisal distance in male was 69mm, minimum 37mm., and maximum interincisal distance in female was 58mm. minimum. 30mm.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.1
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• pp.77-87
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• 2012

In this paper, the method and its effectiveness to decrease the uneven wear of the brake pad were proposed. A finite element analysis was performed to analyze the pressure distributions on the contact surfaces. The optimum brake pad shape was determined by a robust design using the Taguchi method. The effectiveness of the optimum design was clarified by the wear tests with a dynamometer.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2002.11a
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• pp.36-46
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• 2002

The accurate characterization of paper structure may provide critical information for ideal selection of raw materials and papermaking processes as well as for predicting the behavior and the quality of final paper products. In this study, local paper structure and the relationship among the structural parameters, thickness, grammage, apparent density and surface roughness of various handsheet and commercial paper samples were evaluated by using recently developed methods. A new concept of surface roughness was also introduced. The results demonstrate that there is significant overestimation in the measured thickness when using the conventional caliper method that originates from the surface roughness and poor paper formation. A novel non-contact thickness tester, referred to as the twin laser profilometer(TLP), provided results that were not subject to these artifacts and thus provided the local intrinsic thickness and consequently the local intrinsic apparent density.

• Journal of Korean Neurosurgical Society
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• v.29 no.7
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• pp.886-890
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• 2000

Objective : placement of ventricular catheter is important to achieve long-term patency of the shunt system. We describe a method of calculating the insertion site, trajectory, and the length of the ventricular catheter using CT parameters in shunt surgery. Patients and Methods : These can be rapidly obtained using a caliper from a scout cut and two axial scans at lateral ventricular and upper 3rd ventricular level. To compare this technique with traditional one, we analyzed 40 consecutive patients who underwent shunt surgery. Results : Of 20 patients undergoing ventriculoperitoneal shunt insertion using this technique, none had poor location of the proximal catheter. In the counterpart, 9 patients had poor location(p＝0.001). The number of patients who required revision surgery were also lower in the group using this technique, but it was not statistically significant (4 versus 2, p＝0.422). Mean follow-up period was shorter in this technique group. Conclusion : This technique provides an accurate placement of the proximal catheter without special instrument or additional expenses.