• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.173-180
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• 2020

PURPOSE. This study compared digital (reference point matching) and replica methods for measuring marginal and internal fit of full coverage restorations. MATERIALS AND METHODS. A maxillary left first molar typodent was fixed on to an aluminum base and prepared to receive all-ceramic full coverage restoration. The model was scanned with an intraoral scanner (CEREC Omnicam, Sirona, York, PA, USA). Twelve crowns were fabricated from lithium disilicate blocks (IPS emax CAD, Ivoclar Vivadent) and then crystalized. Marginal and internal fit of each restoration was measured by two examiners using replica and a new digital three-dimensional technique. Reliability between the two methods and two examiners was assessed by correlation and Cronbach's Alpha coefficient (P<.05). A Bland-Altman assessment for agreement was used to compare the two methods. RESULTS. Bland-Altman assessment showed that the mean of difference for marginal, absolute marginal, and axial gap was respectively -1.04 ㎛, -41.9 ㎛, and -29.53 ㎛ with limit of agreement (LOA) between -37.26 to 35.18 ㎛ for marginal, -105.85 to 22.05 ㎛ for absolute marginal and -80.52 to 22.02 ㎛ for axial gap. Positive correlation for repeatability (P<.05) in determining marginal and internal gaps by the two examiners in both techniques was revealed. Reliability of both techniques in all sites of measurements was at least good (0.8 ≤ α < 0.9). CONCLUSION. Both measuring techniques appeared highly reliable for evaluating fit of fixed dental restorations, while reference point matching provided higher values in axial and absolute marginal gap assessment.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.358-363
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• 2017

PURPOSE. The purpose of this study was to evaluate the reliability of computer-aided replica technique (CART) by calculating its agreement with the replica technique (RT), using statistical agreement analysis. MATERIALS AND METHODS. A prepared metal die and a metal crown were fabricated. The gap between the restoration and abutment was replicated using silicone indicator paste (n = 25). Gap measurements differed in the control (RT) and experimental (CART) groups. In the RT group, the silicone replica was manually sectioned, and the marginal and occlusal gaps were measured using a microscope. In the CART group, the gap was digitized using optical scanning and image superimposition, and the gaps were measured using a software program. The agreement between the measurement techniques was evaluated by using the 95% Bland-Altman limits of agreement and concordance correlation coefficients (CCC). The least acceptable CCC was 0.90. RESULTS. The RT and CART groups showed linear association, with a strong positive correlation in gap measurements, but without significant differences. The 95% limits of agreement between the paired gap measurements were 3.84% and 7.08% of the mean. The lower 95% confidence limits of CCC were 0.9676 and 0.9188 for the marginal and occlusal gap measurements, respectively, and the values were greater than the allowed limit. CONCLUSION. The CART is a reliable digital approach for evaluating the fit accuracy of fixed dental prostheses.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.210-217
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• 2016

Purpose: The aim of this study was to evaluate the marginal and internal adaptation of monolithic zirconia restoration made without physical model by digital intraoral scanner. Materials and methods: A prospective clinical trial was performed on 11 restorations as a pilot study. The monolithic zirconia restorations were fabricated after digital intraoral impression taking by intraoral scanner (TRIOS, 3shape, Copenhagen, Denmark), computer-aided designing, and milling manufacturing process. Completed zirconia crowns were tried in the patients' mouth and a replica technique was used to acquire the crown-abutment replica. The absolute marginal discrepancy, marginal gap, and internal gap of axial, line angle, and occlusal part were measured after sectioning the replica in the mesiodistal and buccolingual direction. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U test (${\alpha}=.05$). Results: From the adaptation analysis by replica, the statistically significant difference was not found between mesiodistal and buccolingual sections (P>.05), but there was significant difference among the measurement location (P<.01). The amount of absolute marginal discrepancy was larger than those of marginal gap and internal gap (P<.01). Conclusion: Within the limitations of this study, the adaptation accuracy of model-free monolithic zirconia restoration fabricated by intraoral scanner exhibited clinically acceptable result. However, the margin of zirconia crown showed tendency of overcontour and cautious clinical application and follow up is necessary.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.189-194
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• 2024

This paper presents a radiation-hardened-by-design preamplifier that utilizes a self-compensation technique with a charge-sensitive amplifier (CSA) and replica for total ionizing dose (TID) effects. The CSA consists of an operational amplifier (OPAMP) with a 6-bit binary weighted current source (BWCS) and feedback network. The replica circuit is utilized to compensate for the TID effects of the CSA. Two comparators can detect the operating point of the replica OPAMP and generate appropriate signals to control the switches of the BWCS. The proposed preamplifier was fabricated using a general-purpose complementary metal-oxide-silicon field effect transistor 0.18 ㎛ process and verified through a test up to 230 kGy (SiO₂) at a rate of 10.46 kGy (SiO₂)/h. The code of the BWCS control circuit varied with the total radiation dose. During the verification test, the initial value of the digital code was 39, and a final value of 30 was observed. Furthermore, the preamplifier output exhibited a maximum variation error of 2.39%, while the maximum rise-time error was 1.96%. A minimum signal-to-noise ratio of 49.64 dB was measured.

• Electronics and Telecommunications Trends
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• v.39 no.3
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• pp.79-86
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• 2024

Digital twins are gaining attention and traction across various industries and societies owing to their potential for technological advancement, utilization, and service innovation. Digital twins involve creating a software system that mirrors a real-world entity, enabling them to interact and cooperate, therfore resembling interaction between a real-world entity and a digital twin. By recognizing the importance of this technology, international standardization efforts for digital twins are actively underway toward enhancing its application across various industrial sectors. We aims to provide an overview of the current status and future prospects of digital twin standardization, focusing on the ISO/TC 184/SC 4 and ISO/IEC JTC 1/SC 41 efforts.

• Conservation Science in Museum
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• v.29
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• pp.99-110
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• 2023

The stone fragments that are missing from the stone cultural heritage have limited use beyond being directly fitted to identify their original position, as they are relatively heavy and bulky, and there is the further risk of secondary physical damage during manual work. Therefore, in this study, morphological relationships between the missing parts and the stone fragments were identified through digital restoration, and a three-dimensional (3D) printed replica was created for use at the exhibition for Stone Buddhas in Four Directions in Hwajeon-ri, Yesan, where 72 stone fragments had been excavated together. First, for the digital restoration, stone fragments of similar shapes were selected after the coordinates of the 3D scanning model were aligned in virtual space. In addition, the stone fragments were printed using a 3D printer to check whether they were physically related to the missing parts. Thus, the original positions of a total of nine stone fragments were identified. To utilize these research results in the exhibition, a 1:1 replica of the Stone Buddhas in Four Directions was produced using 3D printing technology, and the nine stone fragments were also restored to their original positions. The digital technology used in this study is of great importance in that it not only made up for the limitations of the direct manual method but also suggested the possibility of expanding its application to the fields of documentation, restoration, and replication of similar cultural heritage.

• Journal of Conservation Science
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• v.32 no.1
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• pp.51-61
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• 2016

'Eojin', king's portraits, had been produced during the Joseon dynasty. The portrait of King Taejo, the founder of the Joseon dynasty, remain at National Palace Museum of Korea and Gyeonggijeon portrait hall in Jeonju and Junwonjeon portrait hall in North Korea that has been recorded in original glass plate photo in 1911. Many replica of Eojin have been made since it is important to preserve and protect original one. In this study, the portrait of King Taejo, which is possessed by National Palace Museum of Korea, was researched for making replication standard version of the original form. It was focused on derivations of each artefacts and drawing lines those had been described on the picture including comparison among three portraits of King Taejo. Producing the replication standard version of King Taejo's portrait, the digital restoration techniques by the method of partition area scanning was applied. Accurate and precise detail result that is taken by digital imaging technique gives additional information regarding the relations among three portraits of King Taejo.

• Korean Institute of Interior Design Journal
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• v.18 no.3
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• pp.66-73
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• 2009

In the digital age, as it is ambiguous to distinguish between the original and a replica, the order of reproduction which is more realistic than the reality is becoming a new cultural order. Before the period when digital paradigm dominates, always the reality has been an object to be copied. But, today is an age of Simulacre where code of digital technology dominates. Such a phenomenon is shown in the construction space without exception Gilles Deleuze who was a representative philosopher of the post-structuralism depicted the concept of Simulacre as an instant 'event' passing by without change in an object or substance. As the result of analyzing what kinds of feature for the concept of event is expressed in the digital space, a diagram itself could be a design process, the digital space with correlation was able to be created through the change in the meaning according to the changing image and my body which was the leading part to form primary space. In such a meaning, this study pays attention to Deleuze's 'Event(Simulacre)' concept. At this transitional period when a new concept of digital space is about to take root, the modern philosophers' theories and the discussions about spatial relativity should be continually studied, along with the development of spacial theories for the modem construction.

• The Journal of Advanced Prosthodontics
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• v.9 no.1
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• pp.1-13
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• 2017

PURPOSE. The purpose of this study was to compare the fit of cast gold crowns fabricated from the conventional and the digital impression technique. MATERIALS AND METHODS. Artificial tooth in a master model and abutment teeth in ten patients were restored with cast gold crowns fabricated from the digital and the conventional impression technique. The forty silicone replicas were cut in three sections; each section was evaluated in nine points. The measurement was carried out by using a measuring microscope and I-Soultion. Data from the silicone replica were analyzed and all tests were performed with ${\alpha}$-level of 0.05. RESULTS. 1. The average gaps of cast gold crowns fabricated from the digital impression technique were larger than those of the conventional impression technique significantly. 2. In marginal and internal axial gap of cast gold crowns, no statistical differences were found between the two impression techniques. 3. The internal occlusal gaps of cast gold crowns fabricated from the digital impression technique were larger than those of the conventional impression technique significantly. CONCLUSION. Both prostheses presented clinically acceptable results with comparing the fit. The prostheses fabricated from the digital impression technique showed more gaps, in respect of occlusal surface.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.204-206
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• 2022

Digital twin, which is evaluated as the core of smart factory advancement, is a technology that implements a digital replica in the virtual world with the same properties and functions of assets in the real world. Since the smart factory to which digital twin is applied can support services such as real-time production process monitoring, production process simulation, and predictive maintenance of facilities, it is expected to contribute to reducing production costs and improving productivity. AAS (Asset Administration Shell) is an essential technology for implementing digital twin and supports a method to digitally represent physical assets in real world. In this paper, we design AAS for manufacturing data gathering to be used in real-time CNC (Computer Numerical Control) monitoring system in operation by considering manufacturing facility in smart factory as assets.