• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.53-60
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• 2009

Statement of problem: At present, as the esthetic demands are on the increase, there are many ongoing studies for tooth-colored post and cores. Most of them are about fiber post and prefabricated zirconia post, but few about one-piece milled zirconia post and core using CAD/CAM (computer-aided design/computer-aided manufacturing) technique. Purpose: The objective of this study was to compare microleakage of endodontically treated teeth restored with three different tooth-colored post and cores. Material and methods: Extracted 27 human maxillary incisors were cut at the cementoenamel junction, and the teeth were endodontically treated. Teeth were divided into 3 groups (n=9); restored with fiber post and resin core, prefabricated zirconia post and heat-pressed ceramic core, and CAD/CAM milled zirconia post and core. After the preparation of post space, each post was cemented with dual-polymerized resin cement (Variolink II). Teeth were thermocycled for 1000 cycles between $5-55^{\circ}C$ and dyed in 2% methylene blue at $37^{\circ}C$ for 24 hours. Teeth were sectioned (bucco-lingual), kept the record of microleakage and then image-analyzed using a microscope and computer program. The data were analyzed by one-way ANOVA and Scheffe's multiple range test (${\alpha}=0.05$). Results: All groups showed microleakage and there were no significant differences among the groups (P>.05). Prefabricated zirconia post and heat-pressed ceramic core showed more leakage in dye penetration at the post-tooth margin, but there was little microleakage at the end of the post. Fiber post and resin core group and CAD/CAM milled zirconia post and core group indicated similar microleakage score in each stage. Conclusion: Prefabricated zirconia post and heat-pressed ceramic core group demonstrated better resistance to leakage, and fiber post and resin core group and CAD/CAM milled zirconia post and core group showed the similar patterns. The ANOVA test didn't indicate significant differences in microleakage among test groups. (P>.05)

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2783-2787
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• 2013

To assess the risk of cancer incidence after medical radiation exposure for coronary artery disease (CAD), a retrospective cohort study was conducted based on Taiwan's National Health Insurance Research Database (NHIRD). Patients with CAD were identified according to the International Classification of Diseases code, 9th Revision, Clinical Modification (ICD-9-CM), and their records of medical radiation procedures were collected from 1997 to 2010. A total of 18,697 subjects with radiation exposure from cardiac imaging or therapeutic procedures for CAD were enrolled, and 19,109 subjects receiving cardiac diagnostic procedures without radiation were adopted as the control group. The distributions of age and gender were similar between the two populations. Cancer risks were evaluated by age-adjusted incidence rate ratio (aIRR) and association with cumulative exposure were further evaluated with relative risks by Poisson regression analysis. A total of 954 and 885 subjects with various types of cancers in both cohorts after following up for over 10 years were found, with incidences of 409.8 and 388.0 per 100,000 person-years, respectively. The risk of breast cancer (aIRR=1.85, 95% confidence interval: 1.14-3.00) was significantly elevated in the exposed female subjects, but no significant cancer risk was found in the exposed males. In addition, cancer risks of the breast and lung were increased with the exposure level. The study suggests that radiation exposure from cardiac imaging or therapeutic procedures for CAD may be associated with the increased risk of breast and lung cancers in CAD patients.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.1
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• pp.181-187
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• 2012

Various computer-based simulation tools such as 3D-CAD and CAE systems are widely used to design automotive body structure at the early phase of design. Designers must search the optimal solution that satisfies a number of performance requirements by using their tools and a trial-and-error approach. In the previous three reports, a set-based design approach has been proposed for achieving design flexibility and robustness while capturing designer's preference, and its effectiveness has been illustrated with a simple side-door impact beam design problem and real vehicle side-door structure design. This report presents the development of integrated 3D-CAD and CAE system, and the applicability of our proposal for obtaining the multi-objective satisfactory design solutions by applying to an automotive front-side frame.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.3
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• pp.391-406
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• 1993

The purpose of this study was to utilize of apparel CAD System by the classification of the basic pattern block in pattern making process. Gerber AM-300 CAD System was used for this study. The results form this study were as follows; 1. New shirts block were developed. 2. The sensory test was applied to evaluate the new shirts block for women by comparing it with Japanese Bunka shirts blouse pattern making method. According to a statistical analysis of the result of the 20 items on the questionnaire, the 19 items showed significant difference(${\alpha}{\leq}0.01$)between the two, with the new shirts block having higher scores. 3. A basic pattern block was selected by the design sketch. 4. P/D/S were enabled to be constructed directly from a block pattern. The drawing, deletion. duplication, and movement of all points and lines in the pattern might be made freely, and the split, pivot, and movement of the pattern, and the attachment of two patterns were possible. 5. Automatic grading of finished pattern have been developed by creation and modification of grading rules of block pattern.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.366-376
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• 2013

The purpose of this study is to evaluate the marginal and internal fit of coping made by CAD/CAM using different scanning methods. Zirconia coping was made by each CAD/CAM system followed by intra-oral scanning, model optical scanning and model contact scanning. It was embedded into Epoxy Resin and was cut by buccal to lingual. AMD (Absolute marginal discrepancy), MG (Marginal gap), GA (Gap of axial), GL (Gap of line angle) and GO (Gap of occlusal) of each sample were measured. The result is as followed; 1. The mean value of AMD in Group 1, Group 2, Group 3 are $141.21{\pm}42.94{\mu}m$, $140.63{\pm}31.64{\mu}m$, $109.37{\pm}28.42{\mu}m$. The averages of MG in Group 1, Group 2, Group 3 are $82.52{\pm}43.99{\mu}m$, $90.28{\pm}27.93{\mu}m$, $66.55{\pm}28.77{\mu}m$. Statistically there is no difference in AMD and MG among the three Groups (Anova, P>0.05). 2. GA of Group 2 revealed statistically difference compared with Group 1 and Group 3 (Anova, P<0.05). 3. GL and GO of Group 1 showed statistically significant differences compared with Group 2 and Group 3 (Mann-whitney test (P<0.05). Zirconia copings made by 3 ways of scanning methods have no difference with conventional ceramics in AMD and MG which are known as the most important factors.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.95-107
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• 2009

The purpose of this research was to examine the fitness of zirconia cores that were made by different sintering methods; generic electricity furnace and microwave furnace. Firstly, 12 cores for each group were made by using each different sintering process and attached them to a metal die with silicon. The internal and marginal gap of sintered zirconia was measured by using Skyscan 1076 micro-CT, then it was reorganized by CT-An software. To each samples, we extracted B-L image, M-D image of cutting side, and cross-sectional side of tooth long axis and calculated the mean value of marginal, axial, and occlusal gap each side. Results: 1. The mean marginal gap of sintered zirconia was $36.20{\mu}m$ for EVE, $47.67{\mu}m$ for LAV, $52.47{\mu}m$ for DEN, and $54.63{\mu}m$ for CER. 2. For the axial wall, the research showed the largest value of $63.49{\mu}m$ for EVE, but there were no statistical significance. 3. In related to the occlusal internal measurement, DEN showed the smallest value ($77.06{\mu}m$), EVE and CER showed significantly high value. From this study, it is suggested that CAD/CAM zirconia core which was made in the process of microwave sintering has clinically acceptable values in marginal and internal gap.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.148-155
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• 2009

Statement of problem: The interest in all-ceramic restorations has increased as more techniques have become available. With the introduction of machinable dental ceramics and CAD/CAM systems there is a need to evaluate the quality levels of these new fabrication techniques. Purpose: This study is to evaluate the crown fidelity(absolute marginal discrepancy and internal gap) of various zirconia-based all-ceramic crowns fabricated with different CAD/CAM(computer-assisted design/computer-assisted manufacturing) systems and conventional cast metal-ceramic crowns. Material and methods: A resin tooth of lower right second premolar was prepared. After an impression was taken, one metal master die was made. Then 40 impressions of metal master dies were taken for working dies. 10 crowns per each system were fabricated using 40 working dies. Metal-ceramic crowns were cast by using the conventional method, and Procera, Lava, and Cerec inLab crowns were fabricated with their own CAD/CAM manufactruing procedures. The vertical marginal discrepancies and internal gaps of each crown groups were measured on a metal master die without a luting agent. The results were statistically analyzed using the one-way ANOVA and Tukey's HSD test. Results: 1. Vertical marginal discrepancies were $50.6{\pm}13.9{\mu}m$ for metal-ceramic crowns, $62.3{\pm}15.7{\mu}m$ for Procera crowns, $45.3{\pm}7.9{\mu}m$ for Lava crowns, and $71.2{\pm}2.0{\mu}m$ for Cerec inLab crowns. 2. The Internal gaps were $52.6{\pm}10.1{\mu}m$ for metal-ceramic crowns, $161.7{\pm}18.5{\mu}m$ for Procera crowns, $63.0{\pm}10.2{\mu}m$ for Lava crowns, and $73.7{\pm}10.7{\mu}m$ for Cerec inLab crowns. Conclusion: 1. The vertical marginal discrepancies of, 4 crown groups were all within the clinically acceptable range($120{\mu}m$). 2. The internal gaps of LAVA, Cerec inlab, and metal-ceramic crowns were within clinically acceptable range except Procera crown($140{\mu}m$).

• Korean Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.20-32
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• 1996

The boundary evaluation technique for Boolean operation on non-manifold models which is regarded as the most popular and powerful method to create and modify 3-D CAD models has been developed. This technique adopted the concept of Merge and Selection in which the CSG tree for Boolean operation can be edited quickly and easily. In this method, the merged set which contains complete information about primitive models involved is created by merging primitives one by one, then the alive entities are selected following the given CSG tree. This technique can support the hybrid representation of B-rep(Boundary Representation) and CSG(Constructive Solid Geometry) tree in a unified non-manifold model data structure, and expected to be used as a basic method for many modeling problems such as data representation of form features, and the interference between them, and data representation of conceptual models in design process, etc.

• Journal of Korean Institute of Industrial Engineers
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• v.12 no.2
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• pp.1-11
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• 1986

This study is concerned on computerized analysis of COG, torques and EMG amplitudes in weight-lifting motion. The results show that; (1) torques on major joints show a rather consistent relationship with respect to the sequence of four distinct motions in weight-lifting, (2) analysis of EMG amplitudes is a sensitive measure of both athlete's skill and his potential capability, and (3) range of COG variations can be used as indicator of motion stability, existence of undesirable posture, and target muscle for intensive training. A computerized routine, which includes analyses on COG, EMG and torque, is a scientific tool for coaching athletes. In addition, an Expert System which includes CAD routine was developed in order to promote better understanding for athletes and coaches.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.1-10
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• 1997

Finding the optimum route of ship's pipes is complicated and time-consuming process. Experience of designers is the main tool in this process. To reduce design man-hours and human errors a design expert system shell and a geometric modeler is used to automate the design process. In this paper, a framework of the intelligent CAD system for pipe auto-routing is suggested, which consists of general-purpose expert system shell and a geometric modeler. The design expert system and the geometric modeling kernel have been integrated. The CADDS5 of Computervision is used as the overall CAD environment. The Nexpert Object of Neuron Data is used as the expert system shell. The CADDS5 ISSM is used as the interface that creates and modifies geometric models of pipes. Existing algorithms for the routing problem have been analyzed. Most of them are to solve the 2-D circuit routing problems. Ship piping system, specially within the engine room, is a complicated, large scale 3-D routing problem. Methods of expert system have been used to find the route of ship pipes on the main deck.