• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.1
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• pp.9-20
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• 2023

Purpose: We investigated the effect of open tray impression using pick-up impression coping and close tray impression using transfer impression coping on the accuracy of impression in edentulous patients on their mandibular parts. the effect of material types of pick-up type impression copings for splinting in open tray impression on the accuracy of impression was also evaluated. Materials and Methods: Two implant fixtures were implanted in parallel in the left molar of the mandibular in the shape of a mandibular partial edentulous model. The 40 individual trays were fabricated using 3D printer. The prepared individual trays were classified into 4 groups (i.e., PN, PG, PH, and TN groups), and a total of 40 impression-takings were conducted. A master cast was connected to a Scan Body. The converted STL file was super-imposed on the scan images of the various groups. Results: The order of standard deviation values decreased as follows: PN (0.2343 ± 0.0844 mm), TN (0.2192 ± 0.0840 mm), indicating that the high accuracy of impression for TN group. In addition, for the comparison results between the material types used in splinting the open tray impression, the PH group showed a relatively lower standard deviation (0.1910 ± 0.1176 mm) than that of the PN group (0.2343 ± 0.0844 mm), PG group (0.2556 ± 0.1082 mm). Conclusion: The acrylic resin synthesized by light-induced polymerization exhibited a higher accuracy of impression taking than that of autopolymerizing acrylic resin. Meanwhile, the accuracy of impression taking was not dependent on the implant impression taking method or the presence of connection/fixation of impression copings.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.4
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• pp.505-516
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• 2018

In order to establish an efficient bridge maintenance strategy, the future performance of a bridge must be estimated by considering the current performance, which allows more rational way of decision-making in the prediction model with higher accuracy. However, personnel-based existing maintenance may result in enormous maintenance costs since it is difficult for a bridge administrator to estimate the bridge performance exactly at a targeting management level, thereby disrupting a rational decision making for bridge maintenance. Therefore, in this work, we developed a representative performance prediction model for each bridge element considering uncertainty using domestic bridge inspection data, and proposed a bayesian updating method that can apply the developed model to actual maintenance bridge with higher accuracy. Also, the feasibility analysis based on calculation of maintenance cost for monitoring maintenance scenario case is performed to propose advantages of the Bayesian-updating-driven preventive maintenance in terms of the cost efficiency in contrast to the conventional periodic maintenance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.70-80
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• 2001

A cycloid reducer is one of the rotational velocity reduction equipments of machinery. It has advantages of the higher reduction ratio, the higher accuracy, the easier adjustment of transmission ratio and the smaller workspace than other kinds of reducer. A cycloidal plate gear is a main part of the cycloid reducer. Its tooth shape is peculiar because of gearing with the roller gear that has the several rollers on the circular line. And then it can be designed to contact all teeth to rollers. So, the cycloid reducer has the good characteristics in the dynamic properties and the zero-backlash in the contact motion. It can be used in robots, high-precision machines and high capacity machinery. This paper proposes a new approach for the shape design of the cycloidal plate gear and presents a Computer-Aided-Design program developed by the proposed method. The first part of this paper defines the two types of the cycloid reducers and explains their mechanisms. The second part defines the instant velocity centers for each type of the cycloid reducers and calculates the contact angles and the contact points by using te geometric relationships and the kinematical properties of the reducers. The third part generates the full shape of the cycloidal plate gear by the coordinate transformation technique. Finally, this paper presents two examples for the shape design of the cycloidal plate gear in order to prove the theory of the proposed method in this paper and the accuracy of the \"CycloGear Designer\".

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.1-8
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• 2017

Recently, the development of the head mounted display (HMD) device has attracted a great deal of attention to the actual contents. Especially, Augmented Reality (AR), which is a mixture of actual information and virtual world information, is focused on. AR HMD is able to interact by arranging virtual objects in real space through spatial recognition using depth camera. In order to naturally mix virtual space with real space, it is necessary to develop a technology for realizing spatial mapping information with high accuracy. The purpose of this paper is to evaluate the optimal configuration of augmented reality application program by realizing accurate spatial mapping information when mapping a real space and an object placement environment using HoloLens. To do this, we changed the spatial mapping information in real space to three levels, which are the number of meshes used in cubic meters to scan step by step. After that, it was compared with the 3D model obtained by changing the actual space and mesh number. Experimental result shows that the higher the number of meshes used in cubic meters, the higher the accuracy between real space and spatial mapping. This paper is expected to be applied to augmented reality application programs that require scanning of highly mapped spatial mapping information.

• Structural Engineering and Mechanics
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• v.87 no.5
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• pp.461-473
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• 2023

This study aims to solve for nonlinear cylindrical shell systems with a semi-analytical and numerical approach implementing the P-T method. The procedures and conditions for such a study are presented in practically solving and analyzing the cylindrical shell systems. An analytical model for a nonlinear thick cylindrical shell (TCS) is established on the basis of the stress function and Reddy's higher-order shear deformation theory (HSDT). According to Reddy's HSDT, Hooke's law in three dimensions, and the von-Kármán equation, the stress-strain relations are developed for the thick cylindrical shell systems, and the three coupled nonlinear governing equations are thus established and discretized as per the Galerkin method, for implementing the P-T method. The solution generated with the approach is continuous everywhere in the entire time domain considered. The approach proposed can also be used to numerically solve and analyze the nonlinear shell systems. The procedures and recurrence relations for numerical solutions of shell systems are presented. To demonstrate the application of the approach in numerically solving for nonlinear cylindrical shell systems, a specific nonlinear cylindrical shell system subjected to an external excitation is solved numerically. In numerically solving for the system, the present approach shows higher efficiency, accuracy, and reliability in comparison with that of the Runge-Kutta method. The approach with the P-T method presented is practically sound especially when continuous and high-quality numerical solutions for the shell systems are considered.

• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.621-631
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• 2018

In this paper, an exact analytical solution is developed for the analysis of the post-buckling non-linear response of simply supported deformable symmetric composite beams. For this, a new theory of higher order shear deformation is used for the analysis of composite beams in post-buckling. Unlike any other shear deformation beam theories, the number of functions unknown in the present theory is only two as the Euler-Bernoulli beam theory, while three unknowns are needed in the case of the other beam theories. The theory presents a parabolic distribution of transverse shear stresses, which satisfies the nullity conditions on both sides of the beam without a shear correction factor. The shear effect has a significant contribution to buckling and post-buckling behaviour. The results of this analysis show that classical and first-order theories underestimate the amplitude of the buckling whereas all the theories considered in this study give results very close to the static response of post-buckling. The numerical results obtained with the novel theory are not only much more accurate than those obtained using the Euler-Bernoulli theory but are almost comparable to those obtained using higher order theories, Accuracy and effectiveness of the current theory.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.9-14
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• 2002

A higher order zig-zag plate theory is developed to accurately predict fully coupled mechanical, thermal, and electric behaviors. Both the in-plane displacement and temperature fields through the thickness are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field. Smooth parabolic distribution through the thickness is assumed in the transverse deflection in order to consider transverse normal deformation. Linear zig-zag form is adopted in the electric field. The layer-dependent degrees of freedom of displacement and temperature fields are expressed in tern-is of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses and transverse heat flux. The numerical examples of coupled and uncoupled analysis demonstrate the accuracy and efficiency of the present theory. The present theory is suitable for the predictions of fully coupled behaviors of thick smart composite plate under mechanical, thermal, and electric loadings combined.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.1015-1026
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• 2021

The objective of this study was to determine amino acid and protein contents of brown and milled non-glutinous rice of 13 cultivars in Korea. Protein contents of MRs (milled rices) were in order of Haepum (7.27%) > Hanareum No. 4 (7.14%) > Odae (6.84%). Protein contents of BRs (brown rices) were in order of Haepum (7.68%) > Odae (7.63%) > Hanareum No. 4 (7.60%). The amino acid content was the highest in Haepum (MR 5.76%, BR 6.49%), followed by Haedeul (MR 5.71%, BR 6.30%), and Odae (MR 5.63%, BR 6.29%). The essential amino acid contents of non-glutinous rices were in order of Haepum (MR 2.34%, BR 2.57%) > Haedeul (MR 2.31%, BR 2.48%) > Odae (MR 2.20%, BR 2.56%). The contents of amino acid and protein in BRs were considerably higher than those in MRs. Protein and most of amino acid contents were higher in Haepum than the other cultivars. The certificated reference material (CRM) 1849a (infant/adults nutritional formular) from National Institute of Standard and Technology (NIST) was used as the test sample to determine the precision and accuracy of the analytical method. The regression analyses revealed good correlations (correlation coefficient), greater than 0.99. The recovery values of the amino acids ranged from 93.17 to 99.59%. The limit of detection (LODs) ranged from 0.01 - 0.07 mg·100 g^-1 and the limit of quantitation (LOQs) ranged from 0.03 - 0.21 mg·100 g^-1 for all analytes.

• Journal of IKEEE
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• v.23 no.4
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• pp.1440-1447
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• 2019

Currently, the prevalence of autism spectrum disorders in children is reported to be higher and shows various types of disorders. In particular, they are having difficulty in communication due to communication impairment in the area of social communication and need to be improved through training. Thus, this study proposes a method of acquiring voice information through a microphone mounted on a robot designed through preliminary research and using this information to make intelligent motions. An ANN(Artificial Neural Network) was used to classify the speech data into robot motions, and we tried to improve the accuracy by combining the Recurrent Neural Network based on Convolutional Neural Network. The preprocessing of input speech data was analyzed using MFCC(Mel-Frequency Cepstral Coefficient), and the motion of the robot was estimated using various data normalization and neural network optimization techniques. In addition, the designed ANN showed a high accuracy by conducting an experiment comparing the accuracy with the existing architecture and the method of human intervention. In order to design robot motions with higher accuracy in the future and to apply them in the treatment and education environment of children with autism.

• Radiation Oncology Journal
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• v.35 no.4
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• pp.340-348
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• 2017

Purpose: To evaluate the diagnostic accuracy of computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT) in predicting pelvic lymph node (LN) metastases in patients with cervical cancer. Materials and Methods: From January 2009 to March 2015, 114 patients with FIGO stage IA1-IIB uterine cervical cancer who underwent hysterectomy with pelvic lymphadenectomy and took CT, MRI, and PET/CT before surgery were enrolled in this study. The criteria for LN metastases were a LN diameter ${\geq}1.0cm$ and/or the presence of central necrosis on CT, a LN diameter ${\geq}1.0cm$ on MRI, and a focally increased FDG uptake on PET/CT. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for pelvic LN metastases were estimated. Results: The sensitivity, specificity, PPV, NPV, and accuracy for detection of pelvic LN metastases were 51.4%, 85.9%, 41.3%, 90.1%, and 80.3% for CT; 24.3%, 96.3%, 56.3%, 86.8%, and 84.6% for MRI; and 48.6%, 89.5%, 47.4%, 90.0%, and 82.9% for PET/CT, respectively. The sensitivity of PET/CT and CT was higher than that of MRI (p=0.004 and p= 0.013, respectively). The specificity of MRI was higher than those of PET/CT and CT (p=0.002 and p=0.001, respectively). The difference of specificity between PET/CT and CT was not statistically significant (p=0.167). Conclusion: These results indicate that preoperative CT, MRI, and PET/CT showed low to moderate sensitivity and PPV, and moderate to high specificity, NPV, and accuracy. More efforts are necessary to improve sensitivity of imaging modalities in order to predict pelvic LN metastases.