• Journal of Yeungnam Medical Science
• /
• 제40권3호
• /
• pp.302-307
• /
• 2023

With recent developments in digital dentistry, research on techniques and materials for three-dimensional (3D) printing is actively underway. We report the clinical applications and outcomes of 3D printing of temporary crowns fabricated with polylactic acid (PLA) using a fused deposition modeling (FDM) printer. Five participants were recruited from among patients scheduled to be treated with a single full-coverage crown at a dental clinic in a university medical center from June to August 2022. We used 3D-printed crowns fabricated with PLA using an FDM printer as temporary crowns and were assessed for discomfort, fracture, and dislodging. The 3D-printed temporary crowns were maintained without fracture, dislodging, or discomfort until the permanent prosthesis was ready. The average time required for printing the temporary crowns was approximately 7 minutes. The 3D printing of temporary crowns with PLA using an FDM printer is a convenient process for dentists. However, these crowns have some limitations, such as rough surface texture and translucency; therefore, the 3D printing process should be improved to produce better prostheses.

• Current Optics and Photonics
• /
• 제6권2호
• /
• pp.161-170
• /
• 2022

Three-dimensional (3D) geometric models are introduced to correct vignetting, and a downhill simplex search is applied to determine the coefficients of a 3D model used in digital microscopy. Vignetting is nonuniform illuminance with a geometric regularity on a two-dimensional (2D) image plane, which allows the illuminance distribution to be estimated using 3D models. The 3D models are defined using generalized polynomials and arbitrary coefficients. Because the 3D models are nonlinear, their coefficients are determined using a simplex search. The cost function of the simplex search is defined to minimize the error between the 3D model and the reference image of a standard white board. The conventional and proposed methods for correcting the vignetting are used in experiments on four inspection systems based on machine vision and microscopy. The methods are investigated using various performance indices, including the coefficient of determination, the mean absolute error, and the uniformity after correction. The proposed method is intuitive and shows performance similar to the conventional approach, using a smaller number of coefficients.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제4권3호
• /
• pp.196-203
• /
• 2004

A three-dimensional (3D) IC technology platform is presented for high-performance, low-cost heterogeneous integration of silicon ICs. The platform uses dielectric adhesive bonding of fully-processed wafer-to-wafer aligned ICs, followed by a three-step thinning process and copper damascene patterning to form inter-wafer interconnects. Daisy-chain inter-wafer via test structures and compatibility of the process steps with 130 nm CMOS sal devices and circuits indicate the viability of the process flow. Such 3D integration with through-die vias enables high functionality in intelligent wireless terminals, as vertical integration of processor, large memory, image sensors and RF/microwave transceivers can be achieved with silicon-based ICs (Si CMOS and/or SiGe BiCMOS). Two examples of such capability are highlighted: memory-intensive Si CMOS digital processors with large L2 caches and SiGe BiCMOS pipelined A/D converters. A comparison of wafer-level 3D integration 'lith system-on-a-chip (SoC) and system-in-a-package (SiP) implementations is presented.

• Journal of Computational Design and Engineering
• /
• 제1권1호
• /
• pp.1-12
• /
• 2014

In this paper, we propose a new method of reconstructing the hand models for individuals, which include the link structure models, the homologous skin surface models and the homologous tetrahedral mesh models in a reference posture. As for the link structure model, the local coordinate system related to each link consists of the joint rotation center and the axes of joint rotation, which can be estimated based on the trajectories of optimal markers on the relative skin surface region of the subject obtained from the motion capture system. The skin surface model is defined as a three-dimensional triangular mesh, obtained by deforming a template mesh so as to fit the landmark vertices to the relative marker positions obtained motion capture system. In this process, anatomical dimensions for the subject, manually measured by a caliper, are also used as the deformation constraints.

• Journal of Korean Dental Science
• /
• 제14권2호
• /
• pp.79-89
• /
• 2021

Purpose: The technique introduced in this study describes a technique for surface treatment that applies a photocuring resin to the surface of an interim crown fabricated by three-dimensional (3D) printing without a conventional polishing method. The purpose of this study was to evaluate marginal and internal fit and the intaglio surface trueness of interim crowns after surface treatment of 3D-printed crowns for clinical application. Materials and Methods: An interim crown was fabricated using a 3D printer with digital light-processing technology, and the surface support was removed. After the posttreatment process, the resin was thinly applied to the surface of the interim crown and polymerized to solve the esthetic problem of the surface without the conventional polishing process. In addition, the marginal and internal fits were measured to verify the clinical use of this technique, and the trueness was evaluated to confirm the deformation of the inner surface according to the technical application of the outer surface of the interim crown. The difference before and after the evaluation by a statistical method was verified using an independent t-test (α=0.05). Result: There was no significant difference in the marginal and internal fit before and after the application of this technique (P>0.05). There was no significant difference in intaglio surface trueness before and after the application of this technique (P=0.963). Conclusion: There was no change in the marginal and internal fit or in intaglio surface trueness of the interim crowns to which this technology was applied. This surface treatment technique is a more convenient method for interim crowns fabricated using 3D-printing technology without the conventional polishing process.

• 대한치과기공학회지
• /
• 제34권3호
• /
• pp.213-220
• /
• 2012

Purpose: The aim of this study was to determine the repeatability and reproducibility of two dental scanners. Methods: The master die and the stone replicas(Kavo, Germany) were digitized in touch-probe scanner(Incise, Renishaw, UK), white light scanner(Identica, Medit, Korea) to create 3-dimensional surface-models. The number of points in the point clouds from each reading were calculated and used as the CAD reference model(CRM). Discrepancies between the points in the 3-dimensional surface models and the corresponding CRM were measured by a matching-software(Power-Inspect R2, Delcam Plc, UK). The t-student test for one samples were used for statistical analysis. Results: The reproducibility of both scanner was within $3{\mu}m$, based on mean value. The mean value between measurements made directly on the touch probe scanner digital models and those made on the white light scanner digital models was $2.20-2.90{\mu}m$, and was statistically significant(P<0.05). Conclusion: With respect to adequate data acquisition, the reproducibility of dental scanner differs. Three-dimensional analysis can be applied to differential quality analysis of the manufacturing process as well as to evaluation of different analysis methods.

• 센서학회지
• /
• 제26권1호
• /
• pp.66-72
• /
• 2017

The three dimensional ultrasonic anemometer was constructed to reduce the disadvantages of the two-dimensional anemometer and to be free from the use environment. Three pairs of transmitting and receiving ultrasonic sensors were designed to face each other at an angle of $45^{\circ}$ to the upper and lower surfaces at intervals of $120^{\circ}$. 200 kHz ultrasonic sensor Oscillation, transmission and reception, level detection, power supply circuit were designed and U, V, W wind speed vector components were obtained by measuring the time of first received ultrasonic pulse by transmitting pulse ultrasound. It is implemented as firmware in ARM Coretex-M3 processor so that horizontal and vertical wind direction and wind speed can be converted into digital signal by vector calculation. In this study, The three-dimensional ultrasonic anemometer can complement the disadvantages of the two-dimensional anemometer (mechanical and ultrasonic), and it is expected to gradually replace the two-dimensional anemometer due to its high utilization rate by collecting additional information such as vertical wind.

• 대한인간공학회지
• /
• 제29권6호
• /
• pp.925-932
• /
• 2010

Most of the research on three-dimensional interaction field have showed different accuracy in terms of sensing, mode and method. Furthermore, implementation of interaction has been a lack of consistency in application field. Therefore, this study is to suggest research trends of three-dimensional interaction using meta-analysis. Searching relative keyword in database provided with 153 domestic papers and 188 international papers covering three-dimensional interaction. Analytical coding tables determined 18 domestic papers and 28 international papers for analysis. Frequency analysis was carried out on method of action, element, number, accuracy and then verified accuracy by effect size of the meta-analysis. As the results, the effect size of sensor-based was higher than vision-based, but the effect size was extracted to small as 0.02. The effect size of vision-based using hand motion was higher than sensor-based using hand motion. Therefore, implementation of three-dimensional sensor-based interaction and vision-based using hand motions more efficient. This study was significant to comprehensive analysis of three-dimensional motion recognition for interaction and suggest to application directions of three-dimensional interaction.

• 대한치과기공학회지
• /
• 제34권4호
• /
• pp.369-377
• /
• 2012

Purpose: The aim of study was to compare the dimensional stability of digitized dental stone replica using different color of gypsum materials using a white light scanner with three-dimensional software. Methods: A master model(500B-1, Nissin dental product, Japan) with the prepared lower full arch tooth was used. Several type IV stones(white, yellow, green) were used for 30 stone casts(10 casts each) duplicated a master model of mandible. The master model and the replicas were digitized with the non-contacting white light scanner to create 3-dimensional digital models. The linear distance between the reference points were measured and analyzed on the Delcam Copycad$^{(R)}$(Delcam plc, UK) 3D graphic software. One-way analysis of variance(ANOVA) combined with a Tukey multiple-range test were used to analysis the data(${\alpha}$=0.05). Results: There were considerable differences in mean values between gypsum materials within each color(white, yellow, green), and this difference was statistically significant, p=0.001. Conclusion: Digitization of dental materials on optical scanner was affected by color. Three different color of gypsum materials showed clinically acceptable accuracies of full arch digital model produced by them. Besides, these results will have to be confirmed in further clinical studies.

• 한국멀티미디어학회논문지
• /
• 제8권6호
• /
• pp.807-813
• /
• 2005

The production and authoring of digital multimedia contents are most important fields in multimedia technology. Nowadays web-based technology and related multimedia software technology are growing in the IT industry and these technologies are evolving most rapidly in our life. The technology of digital audio and video processing is utilizing rapidly to improve quality of our life, Also we are more interested in high sense and artistic feeling in the music and entertainment areas by use of three dimensional (3D) digital sound technology continuously as well as 3D digital video technology. The service field of digital audio contents is increasing rapidly through the Internet. And the society of Internet users wants the audio contents service with better quality. Recently Internet users are not satisfying the sound quality with 2 channels stereo but seeking the high quality of sound with 5,] channels such as 3D audio of the movie films. But it might be needed proper hardware equipments for the service of 3D sound to satisfy this demand. In this paper, we expand the simple 3D audio generator developed and propose a web-based music bank by the software development of 3D audio generation player in 3D sound environment with two speakers minimizing hardware equipments, Also we believe that this study would contribute greatly to digital 3D sound service of high quality for music and entertainment mania.