• Journal of Technologic Dentistry
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• v.44 no.3
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• pp.76-80
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• 2022

Purpose: The purpose of this study is to analyze the depth according to curing using photocurable resin for dental three-dimensional printing. Methods: A stainless mold with a height of 4 mm was prepared. Ultraviolet (UV) polymerization resin was injected into the mold. Photocuring was then performed for 5 minutes using a photopolymerizer, and the height was measured using a digital measuring instrument (first group). Second, light polymerization was also performed outside the mold for 5 minutes, and the height was measured using a digital measuring instrument. Third, light polymerization was further performed for 5 minutes, and the height was measured using a digital measuring instrument. Statistical analysis was performed with the Kruskal-Wallis test, which is a nonparametric test (α=0.05). Results: The third group had the largest measurement length, whereas the first group had the smallest. However, the difference between groups was not statistically significant (p>0.05). The color of the first group was different from that of the second and third groups. Conclusion: All of the 4-mm-thick photocured specimens had a curing reaction, but the part that was not directly irradiated with UV did not show its original color.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.248-255
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• 2018

Ensuring the quality of molds is one of the major issues in mass production. In general, securing the quality of the molds is achieved by repeating grinding and die spotting after machining the molds based on engineer's decision. However, this heuristic method is affected by the engineer's skill and working environment. Therefore, a lot of time and resources are needed in order to ensure quality. In this study, ensuring the quality of molds using grinding map which is generated using automatic measurement is proposed. An automatic measuring system based on CMM (Coordinate Measuring Machine) is developed for measuring the molds. This system generates the measurement path automatically using the 3D CAD model of products. CAD (ComputerAided-Design), CAM (Computer-Aided-Manufacturing), and CAQ (Computer-Aided-Quality) technology is integrated using DMIS (Dimensional Measuring Interface Standard) format in the automatic measuring system. After measuring the molds, a grinding map is generated using the gap between the CAD model and measured values of mold. The grinding map displays the machining tendency and the required amount of grinding with values on a 3D map. Therefore, the quality of molds can be ensured with exactness and quickness based on the grinding map. This study shows that integrating the planning, measuring, and analyzing based on computer technology can solve the problem of quality assurance of mold using the proposed method, therefore the productivity can be increased.

• 월간 기계설비
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• s.245
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• pp.39-51
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• 2010

현재 많은 분야에서 사용하고 있는 2D 3D CAD(Computer-Aided Design)는 기하학적 요소들의 그래픽 구현에 주로 활용되어 왔다. CAD를 통해 이전의 수작업 도면작성에서 디지털 도면작성으로 설계 방법의 변화가 촉진됨으로써 설계오류를 크게 줄이는 한편 설계변경에도 많은 편리함을 가져 왔다. 지금 건축 설계의 패러다임은 단순한 기하학적 드로잉에서 '정보'를 만나, 건축의 전 과정뿐 아니라 사후 유지관리에 대한 각종 데이터까지 처리할 수 있는 BIM으로 발전되고 있다. 본지는 컴퓨터 지원 설계의 변천 과정과 건설시장의 새로운 프로세스로 부각되고 있는 BIM의 현황 및 설비업계와의 접목 가능성, 향후 전망 등에 대해 알아본다.

• The Journal of the Korean dental association
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• v.56 no.11
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• pp.622-630
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• 2018

For successful surgery-first approach, accurate prediction of skeletal and dental changes following orthognathic surgery is essential. With recent development of digital technology using computer-aided design/computer-aided manufacturing (CAD/CAM) technology, attempts to provide more predictable orthodontic/orthognathic treatment have been made through 3D virtual surgery and digital tooth setup. A clinical protocol for the surgery-first orthognathic approach using virtual surgery is proposed. A case of skeletal Class III patient with facial asymmetry treated by the surgery-first approach using digital setup and virtual surgery is presented. Advantages and limitations of applying CAD/CAM technology to orthognathic surgery are discussed.

• Journal of Korean society of Dental Hygiene
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• v.22 no.6
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• pp.467-475
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• 2022

Objectives: This study aimed to understand the definitions, types, and principles of computer-aided design/computer-aided manufacturing (CAD/CAM) and scanners due to the introduction of digital workflows. Methods: This study was based on information from the government's law and articles published in academic journals. Results: CAD/CAM is a technology that measures the shape three-dimensionally, saves it as data, designs it into the desired shape, and processes the product. Scanners, which are classified as intraoral and extraoral scanners, measure teeth and the intraoral environment three-dimensionally and convert them into three-dimensional (3D). A 3D printer is a machine that creates a 3D object by layering materials based on a 3D drawing. It can be classified into four types according to the method: extrusion, powder bonding, lamination, and photopolymerization methods. The most used 3D printer methods in dentistry are stereolithograhpy and digital light processing, and they are widely used in prosthetic, surgical, and orthodontic fields. Conclusions: As the dental system is digitized, it is expected that the government will classify the dental hygienist scope of work and the universities will reflect the curriculum; it is necessary to develop excellent dental hygienists, diversify the educational pathways, and establish policies to meet the needs of the increasing number of patients.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.149-152
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• 1999

Computer-Aided Engineering (CAE) is one of the most effective method in design of golf clubs for determination of optimum shapes in short lead time. A new design of golf club drive with gas-filled titanium head has been carried out using two FEM softwares MARC and DYNA-3D. The main research work focuses on the decision of face thickness and the effect of filled gas pressure by analyzing the change of the kinematic energy of the ball during impact.

• International Journal of CAD/CAM
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• v.9 no.1
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• pp.121-128
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• 2010

The purpose of this study is to clarify the mechanical behavior of human lumbar vertebrae (L3/L4) with and without fusion bone under physiological axial compression. The author has developed the program code to build the patient specific three-dimensional geometric model from the computed tomography (CT) images. The developed three-dimensional model provides the necessary information to the physicians and surgeons to visually interact with the model and if needed, plan the way of surgery in advance. The processed data of the model is versatile and compatible with the commercial computer aided design (CAD), finite element analysis (FEA) software and rapid prototyping technology. The actual physical model is manufactured using rapid prototyping technique to confirm the executable competence of the processed data from the developed program code. The patient specific model of L3/L4 vertebrae is analyzed under compressive loading condition by the FEA approach. By varying the spacer position and fusion bone with and without pedicle instrumentation, simulations were carried out to find the increasing axial stiffness so as to ensure the success of fusion technique. The finding was helpful in positioning the fusion bone graft and to predict the mechanical stress and deformation of body organ indicating the critical section.

• The korean journal of orthodontics
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• v.53 no.1
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• pp.45-53
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• 2023

Objective: This study aimed to evaluate the shear bond strength (SBS) of orthodontic brackets bonded to three-dimensionally (3D)-printed materials after various surface treatments and artificial aging compared with that bonded to computer-aided design/computer-aided manufacturing (CAD-CAM) polymethyl methacrylate (PMMA)-milled materials. Methods: Eighty cylindrical specimens were 3D printed and divided into the following four subgroups (n = 20 each) according to the surface treatment and artificial aging procedure. Group A, sandblasted with 50 ㎛ aluminum oxide particles (SA) and aging; group B, sandblasted with 30 ㎛ silica-coated alumina particles (CO) and aging; group C, SA without aging; and group D, CO without aging. For the control group, 20 CAD-CAM PMMA-milled cylindrical specimens were sandblasted with SA and aged. The SBS was measured using a universal testing machine (0.25 mm/min), examined at ×2.5 magnification for failure mode classification, and statistically analyzed (p = 0.05). Results: The retention obtained with the 3D-printed materials (groups A-D) was higher than that obtained with the PMMA-milled materials (control group). However, no significant difference was found between the study and control groups, except for group C (SA without aging), which showed significantly higher retention than the control group (PMMA-SA and thermocycling) (p = 0.037). Study groups A-D predominantly exhibited a cohesive specimen mode, indicating specimen fracture. Conclusions: Orthodontic brackets bonded to 3D-printed materials exhibit acceptable bonding strengths. However, 3D-printed materials are prone to cohesive failure, which may result in crown fractures.

• 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.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.4.1-4.6
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• 2016

Background: Most cases of facial asymmetry involve yaw deformity, and determination of the yaw correction level is very difficult. Methods: We use three-dimensional soft tissue simulation to determine the yaw correction level. This three-dimensional simulation is based on the addition of cephalometric prediction to gradual yaw correction. Optimal yaw correction is determined visually, and an intermediate splint is fabricated with computer-aided design and computer-aided manufacturing. Application of positioning devices and the performance of horseshoe osteotomy are advisable. Results: With this procedure, accurate repositioning of jaws was confirmed and patients obtained fairly good facial contour. Conclusions: This procedure is a promising method for a widespread, predictable treatment of facial asymmetry.