• The Journal of Korean Academy of Prosthodontics
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• v.50 no.1
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• pp.36-43
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• 2012

Purpose: To analyze the stress distribution of the implant and its supporting structures through 3D finite elements analysis for implants with different hexagon heights and to make the assessment of the mechanical stability and the effect of the elements. Materials and methods: Infinite elements modeling with CAD data was designed. The modeling was done as follows; an external connection type ${\phi}4.0mm{\times}11.5mm$ Osstem$^{(R)}$ USII (Osstem Co., Pusan, Korea) implant system was used, the implant was planted in the mandibular first molar region with appropriate prosthetic restoration, the hexagon (implant fixture's external connection) height of 0.0, 0.7, 1.2, and 1.5 mm were applied. ABAQUS 6.4 (ABAQUS, Inc., Providence, USA) was used to calculate the stress value. The force distribution via color distribution on each experimental group's implant fixture and titanium screw was studied based on the equivalent stress (von Mises stress). The maximum stress level of each element (crown, implant screw, implant fixture, cortical bone and cancellous bone) was compared. Results: The hexagonal height of the implant with external connection had an influence on the stress distribution of the fixture, screw and upper prosthesis and the surrounding supporting bone. As the hexagon height increased, the stress was well distributed and there was a decrease in the maximum stress value. If the height of the hexagon reached over 1.2mm, there was no significant influence on the stress distribution. Conclusion: For implants with external connections, a hexagon is vital for stress distribution. As the height of the hexagon increased, the more effective stress distribution was observed.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.7
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• pp.1109-1120
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• 2009

This study develops a fitted torso type basic pattern for men by utilizing 3D body scan data. Recent fashion trends are reflected in the development of the pattern. The subjects were 15 men in their 20's, who wear size 95 (M size). Body scan data was obtained through a 3D whole body scanner (WB4, Cyberware, USA), and a body surface development figure for developing male fitted torso type basic pattern was attained through the use of Rapid Form 2006 as well as Auto CAD 2006 programs. The results are as follows: A body surface development figure through body surface segment method showed high exactitude in an error range of 100$\pm$1%. In addition, it occurred in an error range of 100:1:3% because of the hard scanning conditions in the incline of the shoulder and armpit areas. However, the body surface development figure as well as the direct measurement results can be used as basic data for the given patternmaking since the error range falls into 100$\pm$3%. Dart amounts obtained from the average cross section were center back 2.2cm (24.3%), back armpit point 3.8cm (41.8%), front armpit point 3.0cm (33.9%). As shown the jacket pattern, the biggest dart amount was portioned out at the back armpit point. The drafting equations for the development pattern acquired are as follows; Full width=C/2+5cm, back length=height/4-1cm, armhole depth=(C/10+12cm)+3cm, back width=2C/10+2cm, front width=2C/10. The development pattern was a fitted torso basic pattern that was composed of 3 pieces, so it would be very useful in developing shirt or jacket patterns. According to the results of the evaluation of the developed pattern appearance, it obtained higher scores of over 3.5 points in almost items, meaning that the developed pattern is appropriate for a male fitted torso type basic pattern. It suggests a possibility of patternmaking from a body surface development figure in 2-D to prototype.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.209-218
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• 2012

Recently, the Field Programmable Stateful Logic Array (FPSLA) was proposed as one of the most promising system integration technologies which will extend the life of the Moore's law. This work is the first proposal of the FPSLA design automation flow, and the approaches to logic synthesis, synchronization, physical mapping, and automatic placement of the FPSLA designs. The synchronization at each gate for pipelining determines the x-coordinates of cells, and reduces the placement to 1-dimensional problems. The objective function and its gradients for the non-linear optimization of the net length and placement density have been remodeled for the reduced global placement problem. Also, a recursive algorithm has been proposed to legalize the placement by relaxing the density overflow of bipartite bin groups in a top-down hierarchical fashion. The proposed model and algorithm are implemented, and validated by applying them to the ACM/SIGDA benchmark designs. The output state of a gate in an FPSLA needs to be duplicated so that each fanout gate can be connected to a dedicated copy. This property has been taken into account by merging the duplicated nets into a hyperedge, and then, splitting the hyperedge into edges as the optimization progresses. This yields additional 18.4% of the cell count reduction in the most dense logic stage. The practicality of the FPSLA can be further enhanced primarily by incorporating into the logic synthesis the constraint to avoid the concentrated fains of gates on some logic stages. In addition, an efficient algorithm needs to be devised for the routing problem which is based on a complicated graph. The graph models the nanowire crossbar which is trimmed to be embedded into the FPSLA fabric, and therefore, asymmetric. These CAD tools can be used to evaluate the fabric efficiency during the architecture enhancement as well as automate the design.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.209-223
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• 2013

This study was to evaluate the stress distributions of prefabricated, customized abutments and fixtures according to their material and shape by three-dimensional finite element analysis. And to investigate the fatigue life and fracture characteristics. Mandibular models were fabricated by reconstruction of the CT scan of patients with normal occlusion. A total of six finite element models were designed, a load of 100 N was applied on the buccal cusps vertically, and 30 degree obliquely. 10 specimens each were fabricated for the more clinically widely used 4 type abutments and were loaded according to ISO 14801. Differences in stress distribution patterns were not found according to the materials of the abutments and fixtures. But a slight difference in the stress level was detected. Customized abutment groups showed lower crown stress levels. One-piece zirconia implant showed the lowest bone stress levels. In the fatigue test, highest values were measured in group 7. Prefabricated abutments showed less variation of fatigue life (P<0.05). Use of customized abutments can improve the fracture resistance of restorations. Especially, use of customized zirconia abutments reinforced by titanium screw connecting parts is recommended.

• Journal of Technologic Dentistry
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• v.40 no.4
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• pp.217-224
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• 2018

Purpose: The aim of this study was to evaluate accuracy of three type complete mandibular denture of before and after polymerization. Methods: Mandibular edentulous model was selected as the master model. 15 study models were made by Type IV stone. Wax complete mandibular dentures were produced by the denture base and artificial teeth. Before and after curing, STL files were obtained using a blue scanner. By superimposing the digitized complete mandibular denture data(after curing) with the CAD-reference(before curing) three-dimensionally, visual fit-discrepancies were drawn by calculating the root mean square (RMS) and visualized on a color-difference map. Each calculated RMS-value was statistically analyzed by 1-way analysis of variance(ANOVA) (${\alpha}=.05$). Results: Mean(SD) RMS-values was OM group $88.98(6.10){\mu}m$, BM group $82.35(13.46){\mu}m$, BDM group $77.83(9.46){\mu}m$. The results of the 1-way ANOVA showed no statistically significant differences in the RMS values of the Three groups for the material (P > .241). Conclusion : Deformation of artificial teeth position was observed in all groups after resin polymerization. But the values, all group were within the clinically acceptable range. The values of BDM group showed the least deformation than the other two groups.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.4
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• pp.487-496
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• 2021

Full mouth rehabilitation is re-organizing the occlusion of the remaining teeth and missing teeth considering the functions, esthetics, and neuromuscular harmony. With the loss of multiple teeth, the patient's occlusal plane gradually collapses and the vertical dimension can be reduced. Since reduced vertical dimension can be a potential etiology of the temporomandibular joint and masticatory muscles, prosthetic restoration with increased vertical dimension is required. This case report is about a 68 years old patient with vertical dimension loss due to worn dentition and multiple loss of teeth. In this case, the loss of vertical dimension is assessed carefully using the digital dentistry technology. Using CAD software in digital analysis step, the occlusal plane was established and evaluated using several criteria. Orienting the position of the bone and teeth using CBCT image, patient's condition was visualized in 3 dimension and treatment planning was possible virtually. The information that matches the patient's condylar position with the articulator, which is the virtual face bow, is reproduced on the actual articulator, and evaluated again. After the evaluation, provisional prosthesis was fabricated and it was confirmed that the patient adapts without any abnormality. This was implemented as a final prosthesis. As a result, the patient obtained satisfying results, utilizing the benefits of digital dentistry technology and traditional methods.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.253-262
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• 2006

In this paper, collision analysis is carried out between two FRP fishing boats. A computer simulation with finite element method is used to accomplish this objective. At first, a detailed geometric model of the boat is constructed using 3-D CAD program. The formation of a finite element from a geometric data of the boats is carried out using HYPERMESH that is the commercial software for mesh generation and post processing. Twelve collision configurations are established by combining two kinds of contact angle($90^{\circ},\;135^{\circ}$) and three different speed(5, 10, 15knot) for small and large boats. Collision analysis is accomplished using DYNA3D. Stress distribution and deformation shape are investigated for each collision condition. In general, $90^{\circ}$ collision angle generate larger stress than $135^{\circ}$ case and the collision for two moving boats showed larger maximum stress than the case that one is moving and the other is stationary. When analysis is carried out until 150ms contact parts of two boats are broken for 10 and 15knot collision speed, in which maximum stress is larger than ultimate strength of the material.

• Journal of dental hygiene science
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• v.15 no.1
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• pp.54-59
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• 2015

The present study investigated the influences of various abutment teeth shapes (maxillary right canine, pre-molar, molar) on the marginal adaptation of computer aided design/computer aided manufacturing-fabricated zirconia core. In vitro adaptation of zirconia cores manufactured by three different abutments were evaluated. Thirty zirconia cores were made per each models and the adaptation was evaluated through a silicone replica technique. The measurement of the adaptation was carried out using digital microscope. The mean and standard deviation of each reference point were analyzed using the one-way (ANOVA) and Tukey's honestly significant difference tests (${\alpha}=0.05$). The overall marginal fits of the zirconia cores were as follows: canine: $47.59{\mu}m$, pre-molar: $43.74{\mu}m$, molar: $40.36{\mu}m$. They were no statistically significant differences between groups for adaptation (p>0.05). This confirmed that the type of abutment teeth used does not determine the precision of fit of zirconia core.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.2
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• pp.120-127
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• 2015

Purpose: The aim was to investigate the effect of implant thread designs on the stress dissipation of the implant. Materials and methods: The threads evaluated in this study included the V-shaped, buttress, reverse buttress, and square-shaped threads, which were of the same size (depth). Building four different implant/bone complexes each consisting of an implant with one of the 4 different threads on its cylindrical body ($4.1mm{\times}10mm$), a force of 100 N was applied onto the top of implant abutment at $30^{\circ}$ with the implant axis. In order to simulate different osseointegration stages at the implant/bone interfaces, a nonlinear contact condition was used to simulate immature osseointegration and a bonding condition for mature osseointegration states. Results: Stress distribution pattern around the implant differed depending on the osseointegration states. Stress levels as well as the differences in the stress between the analysis models (with different threads) were higher in the case of the immature osseointegration state. Both the stress levels and the differences between analysis models became lower at the completely osseointegrated state. Stress dissipation characteristics of the V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration. These results indicated that implant thread design may have biomechanical impact on the implant bed bone until the osseointegration process has been finished. Conclusion: The stress dissipation characteristics of V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration.

• Korean Journal of Community Nutrition
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• v.26 no.5
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• pp.327-336
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• 2021

Objectives: This study was conducted to create a 3D printable snack dish model for the elderly with low food or fluid intake along with barriers towards eating. Methods: The decision was made by the hybrid-brainstorming method for creating the 3D model. Experts were assigned based on their professional areas such as clinical nutrition, food hygiene and chemical safety for the creation process. After serial feedback processes, the grape shape was suggested as the final model. After various concept sketching and making clay models, 3D-printing technology was applied to produce a prototype. Results: 3D design modeling process was conducted by SolidWorks program. After considering Dietary reference intakes for Koreans (KDRIs) and other survey data, appropriate supplementary water serving volume was decided as 285 mL which meets 30% of Adequate intake. To consider printing output conditions, this model has six grapes in one bunch with a safety lid. The FDM printer and PLA filaments were used for food hygiene and safety. To stimulate cognitive functions and interests of eating, numbers one to six was engraved on the lid of the final 3D model. Conclusions: The newly-developed 3D model was designed to increase intakes of nutrients and water in the elderly with dementia during snack time. Since dementia patients often forget to eat, engraving numbers on the grapes was conducted to stimulate cognitive function related to the swallowing and chewing process. We suggest that investigations on the types of foods or fluids are needed in the developed 3D model snack dish for future studies.