• 제목/요약/키워드: FreeCad

검색결과 150건 처리시간 0.041초

CAD/CAM 세라믹 인레이에 대한 3종의 레진 시멘트의 전단결합강도에 관한 연구 (Shear bond strength of the three different kinds of resin cement on CAD/CAM ceramic inlay)

  • 백철우;박철우;박준섭;류재준
    • 대한치과보철학회지
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    • 제51권1호
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    • pp.20-26
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    • 2013
  • 연구 목적: 본 연구는 최근 심미수복에 주로 사용되는 CAD/CAM 세라믹 인레이와 각종 레진 시멘트간의 결합강도를 알아보고자 하였다. 연구 재료 및 방법: 원기둥 모양의 세라믹 블록(높이: 5 mm, 직경: 3 mm)을 Cerec3로 제작하고, 총 90개의 우식이 없는 대구치의 상아질 표면에 세 종류의 레진 시멘트(Unicem$^{(R)}$, Biscem$^{(R)}$, Variolink II$^{(R)}$)를 사용하여 각각 제조업체의 지시에 따라 접착했다. 90개의 시편을 레진 시멘트의 종류에 따라 3개의 군으로 나누고, 각 군의 절반은 $5-55^{\circ}C$, 5,000 cycle 조건 하에서 thermocycling을 시행하였고, 다른 절반은 시행하지 않았다. 모든 시편은 결합강도를 측정하기 전에 $37^{\circ}C$ 생리 식염수에 24시간 동안 보관되었다. 전단결합강도는 만능시험기를 이용하여 0.5 mm/min의 cross head speed로 측정하였다. 결과 값은 t-test 및 one-way ANOVA를 사용하여 통계 분석하였다. 결과: Unicem$^{(R)}$ 군의 전단결합강도가 thermocycling 후에 약간 감소했으나 3 개의 군 중 가장 높은 결합 강도를 보였다. Unicem$^{(R)}$ 및 Valiolink II$^{(R)}$ 군의 전단결합강도가 thermocycling에 영향을 받았지만 Biscem$^{(R)}$은 영향을 받지 않았다(P<.05). Thermocyling 전에는 3개의 군 간의 결합강도에 유의한 차이가 없었지만, thermocyling 후에는 Unicem$^{(R)}$과 Valiolink II$^{(R)}$ 군 간에 유의한 차이가 있었다(P<.05). 결론:CAD/CAM 세라믹 인레이 수복물을 치아에 접착할 때, etch-and-rinse 레진 시멘트인 Valiolink II$^{(R)}$ 대신self-adhesive 레진 시멘트인 Unicem$^{(R)}$과 Biscem$^{(R)}$을 사용해도 임상적으로 유용하다.

지르코잔 프레타우 블럭을 이용한 Full Zirconia 수복 시 심미에 관한 임상적 소견 (Clinical remarks about esthetics in the case of full zirconia restoration utilizing Zirkonzahn Prettau® block)

  • 박종찬
    • 대한심미치과학회지
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    • 제22권1호
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    • pp.30-46
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    • 2013
  • 치과에서 수복물제작에는 지난 50년간 금속을 이용한 금속도재관이 많이 사용되어 왔다. 그러다 보니 심미적이고 생체 친화적이며 금속 알러지등의 문제로 인한 환자들의 사고의 변화에 따라서 'metal free restoration'에 대한 관심이 점점 높아지고 있다. 특히 그 동안 많이 사용되어왔던 귀금속 가격이 급등하여 더 이상 구강 내 수복 물로써 제 역할을 하는 것은 불가능하게 되었으며, PFM수복은 술자로 하여금 chipping과 파절로 인한 문제점을 안고 있다. 따라서 구치부 임플란트 수복물로써 보다 심미적이고 강도가 높은 재료의 요구로 인하여 그 어느 때보다 CAD/CAM이 주목을 받고 있다. Full zirconia 수복을 위해서 고려해야 할 사항은 1. 강도 2. 콤비네이션 작업은? 3. 빛 투과성은? 4. crack이 발생한 경우의 처치는? 5. 블럭의 색조 재현상은? 6. 대합치 마모도 7. 저온 열화 현상 등을 들 수가 있는데, 본 연구에서는 블럭의 색조 재현상에 대해서 정리하고자 한다. Full zirconia 수복을 꺼려하는 가장 커다란 이유 중에 하나가 바로 기존의 PFM 수복과 비교했을 때 자연스러운 색조를 재현하기가 어렵다는 점이며, 교합 조정 후에 컬러링한 표면이 삭제된 후 나타나는 보기 싫은 블럭의 노출로 인하여 많은 임상가들이 꺼려하고 있다. 지르코잔의 블럭을 약 4년 여 동안 사용하면서 이러한 점들은 어느 정도 극복되어질 수 있는 문제라고 여겨지며, 어떻게 하면 그 가급적 주변 보철물 또는 자연 치아와의 조화 이룰 수 있는 수복물을 만들 수 있을 것인가에 관해 정리였다.

Prognostic Factors in Patients Treated with DrugCoated Balloon Angioplasty for Symptomatic Peripheral Artery Disease

  • Sigala, Fragiska;Galyfos, George;Stavridis, Kyriakos;Tigkiropoulos, Konstantinos;Lazaridis, Ioannis;Karamanos, Dimitrios;Mpontinis, Vangelis;Melas, Nikolaos;Zournatzi, Ioulia;Filis, Konstantinos;Saratzis, Nikolaos
    • Vascular Specialist International
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    • 제34권4호
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    • pp.94-102
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    • 2018
  • Purpose: Aim of this study is to report real-life experience on the treatment of peripheral artery disease (PAD) with a specific drug-coated balloon (DCB), and to evaluate potential prognostic factors for outcomes. Materials and Methods: This is a retrospective study reporting outcomes in patients with PAD who were treated with the Lutonix DCB during a four-year period. Major outcomes included: all-cause mortality, amputation, clinical improvement, wound healing and target lesion revascularization (TLR). Mean follow-up was $24.2{\pm}2.3$ months. Results: Overall, 149 patients (mean age: $68.6{\pm}8.3$ years; 113 males) were treated, either for intermittent claudication (IC) (n=86) or critical limb ischemia (CLI) (n=63). More than half the target lesions (n=206 in total) were located in the superficial femoral artery and 18.0% were below-the-knee lesions. CLI patients presented more frequently with infrapopliteal (P=0.002) or multilevel disease (P=0.0004). Overall, all-cause mortality during follow-up was 10.7%, amputation-free survival was 81.2% and TLR-free survival was 96.6%. CLI patients showed higher all-cause mortality (P=0.007) and total amputation (P=0.0001) rates as well as lower clinical improvement (P=0.0002), compared to IC patients. Coronary artery disease (CAD), gangrene and infrapopliteal disease were found to be predictors for death whereas CLI and gangrene were found to be predictors for amputation, during follow-up. Conclusion: PAD treatment with Lutonix DCBs seems to be an efficient and safe endovascular strategy yielding promising results. However, CAD, gangrene, CLI and infrapopliteal lesions were found to be independent predictors for adverse outcomes. Larger series are needed to identify additional prognostic factors.

식물체 내에서 Strontium의 대사 : 밀(Triticum aestivum L.)의 발아과정중 Polyamine 생합성에 미치는 Strontium의 영향 (Strontium Metabolism in Higher Plants: Effect of Strontium of the Polyamine Biosynthesis during Germination of Wheat(Triticum aestivum L.))

  • 김태완;게오르그하인리히
    • 한국환경농학회지
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    • 제14권1호
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    • pp.55-71
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    • 1995
  • 소맥 종자의 발아 과정중 strontium의 생리적 작용을 규명하기 위해 초엽, 종근 및 배유에서의 free amine의 함량변화가 측정되었다. $GA_3$를 포함한 배양액에 strontium 농도의 증가는 종근에서의 putrescine과 초엽에서의 spermidine의 축적을 현저히 유발하였다. $10\;{\mu}M$ 정도의 저농도에서도 strontium에 의한 putrescine 증가는 뚜렷한 반면, spermidine 증가는 10 mM의 고농도 처리에서 현저했다. 종근 생장을 억제하는 1mM 내지 10mM의 strontium 농도에서, g 생체중당 putrescine 수준은 동일농도 calcium 처리에서 보다 각각 22.4배와 15.3배 높았다. 특히 putrescine과 spermidine 증가에 의한 총 free amine 수준의 중가는 생체중 대비 뿐만이 아닌 RNA 함량 대비에서도 중요한 생리적 반응으로 보여졌다. Strontium과 대조적으로 고농도 calcium (10 mM) 처리는 초엽과 종근에서의 agmatine과 cadaverine 함량의 증가를 유발했다. Cadaverine은 calcium을 처리했을 경우에만 검출되었다. 그러나 $1\;{\mu}M$ 에서 1 mM 수준의 calcium 처리는 총 free amine 함량의 감소를 가져왔다. Strontium과 calcium 존재하에서의 발아과정중 축적되는 amine 종류의 차이와 총 free amine 중 diaminine 비율과 총 free amine 중 Polyamine 비율의 변화는 strontium과 calcium 간의 생리적 대사반응의 차이중 하나로 판단되었다.

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BIM 기반 비정형 건축물 패널화 모델 생성 방법에 관한 연구 (BIM-Based Generation of Free-form Building Panelization Model)

  • 김양길;이윤구;함남혁;김재준
    • 한국BIM학회 논문집
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    • 제12권4호
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    • pp.19-31
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    • 2022
  • With the development of 3D-based CAD (Computer Aided Design), attempts at freeform building design have expanded to small and medium-sized buildings in Korea. However, a standardized system for continuous utilization of shape data and BIM conversion process implemented with 3D-based NURBS is still immature. Without accurate review and management throughout the Freeform building project, interference between members occurs and the cost of the project increases. This is very detrimental to the project. To solve this problem, we proposed a continuous utilization process of 3D shape information based on BIM parameters. Our process includes algorithms such as Auto Split, Panel Optimization, Excel extraction based on shape information, BIM modeling through Adaptive Component, and BIM model utilization method using ID Code. The optimal cutting reference point was calculated and the optimal material specification was derived using the Panel Optimization algorithm. With the Adaptive Component design methodology, a BIM model conforming to the standard cross-section details and specifications was uniformly established. The automatic BIM conversion algorithm of shape data through Excel extraction created a BIM model without omission of data based on the optimized panel cutting reference point and cutting line. Finally, we analyzed how to use the BIM model built for automatic conversion. As a result of the analysis, in addition to the BIM utilization plan in the general construction stage such as visualization, interference review, quantity calculation, and construction simulation, an individual management plan for the unit panel was derived through ID data input. This study suggested an improvement process by linking the existing research on atypical panel optimization and the study of parameter-based BIM information management method. And it showed that it can solve the problems of existing Freeform building project.

R/P 마스터 모델을 활용한 정밀주조 부품 및 쾌속금형 제작 공정기술의 개발 (Development of Rapid Tooling using Investment Casting & R/P Master Model)

  • 정해도;김화영
    • 한국주조공학회지
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    • 제20권5호
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    • pp.330-335
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    • 2000
  • Functional metal prototypes are often required in numerous industrial applications. These components are typically needed in the early stage of a project to determine form, fit and function. Recent R/P(Rapid Prototyping) part are made of soft materials such as plastics, wax, paper, these master models cannot be employed durable test in real harsh working environment. Parts by direct metal rapid tooling method, such as laser sintering, by now are hard to get net shape, pores of the green parts of powder casting method must be infiltrated to get proper strength as tool, and new type of 3D direct tooling system combining fabrication welding arc and cutting process is reported. But a system which can build directly 3D parts of high performance functional material as metal park would get long period of system development, massive investment and other serious obstacles, such as patent. In this paper, through the rapid tooling process as silicon rubber molding using R/P master model, and fabricate wax pattern in that silicon rubber mold using vacuum casting method, then we translated the wax patterns to numerous metal tool prototypes by new investment casting process combined conventional investment casting with rapid prototyping & rapid tooling process. With this wax-injection-mold-free investment casting, we developed new investment casting process of fabricating numerous functional metal prototypes from one master model, combined 3-D CAD, R/P and conventional investment casting and tried to expect net shape measuring total dimension shrinkage from R/P pare to metal part.

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A Shortest Path Planning Algorithm for Mobile Robots Using a Modified Visibility Graph Method

  • Lee, Duk-Young;Koh, Kyung-Chul;Cho, Hyung-Suck
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2003년도 ICCAS
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    • pp.1939-1944
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    • 2003
  • This paper presents a global path planning algorithm based on a visibility graph method, and applies additionally various constraints for constructing the reduced visibility graph. The modification algorithm for generating the rounded path is applied to the globally shortest path of the visibility graph using the robot size constraint in order to avoid the obstacle. In order to check the visibility in given 3D map data, 3D CAD data with VRML format is projected to the 2D plane of the mobile robot, and the projected map is converted into an image for easy map analysis. The image processing are applied to this grid map for extracting the obstacles and the free space. Generally, the tree size of visibility graph is proportional to the factorial of the number of the corner points. In order to reduce the tree size and search the shortest path efficiently, the various constraints are proposed. After short paths that crosses the corner points of obstacles lists up, the shortest path among these paths is selected and it is modified to the combination of the line path and the arc path for the mobile robot to avoid the obstacles and follow the rounded path in the environment. The proposed path planning algorithm is applied to the mobile robot LCAR-III.

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단속형 가변적층쾌속조형공정을 이용한 3차원 스캔데이터로부터 3차원 시작품의 쾌속 제작 (Rapid Manufacturing of 3D Prototype from 3D scan data using VLM-ST)

  • 이상호;안동규;김효찬;양동열;박두섭;채희창
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2002년도 춘계학술대회 논문집
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    • pp.536-539
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    • 2002
  • The reverse engineering (RE) technology can quickly generate 3D point cloud data of an object by capturing the surface of a model using a 3D scanner. In the rapid prototyping (RP) technology, prototypes are rapidly produced from 3D CAD models in a layer-by-layer additive basis. In this paper, a physical human head shape is duplicated using a new RP process, the Transfer-type Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-ST), after the point cloud data of a human head shape measured from 3D SNX scanner are converted to STL file. From the duplicated human head shape, it has been shown that the VLM-ST process in connection with the 3D scanner is a fast and efficient process in that shapes with free surface, such as the human head shape, can be duplicated with ease. Considering the measurement time and the shape duplication time, the use of 3D SNX scanner and the VLM-ST process is expected to reduce the lead-time fur the development of new products in comparison with the other existing RE-RP connected manufacturing systems.

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VLM-S용 선형열선절단기의 회전각 계산 (Calculation of Rotation Angle of the Linear Hotwire Cutting System for VLM-s)

  • 이상호;안동규;양동열
    • 한국정밀공학회지
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    • 제19권2호
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    • pp.87-94
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    • 2002
  • Most of Rapid Prototyping (RP) process adopt a solid Computer Aided Design (CAD) model, slicing into thin layers of uniform, but not necessarily constant, thickness in the building direction. Each cross-sectional layer is successive1y deposited and at the same time, bonded onto the previous layers; the stacked layers form a physical part of the model. The objective of this study is to develop a method for calculating the rotation angle ($$\theta$_x, $\theta$_y$) of hotwire of the cutting system in the three-dimensional space for the Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-S). In order to examine the applicability of the developed method to VLM-S, various three-dimensional shapes. such as a screw, an extruded cross, and free surface bodies such as miniatures of the monkey(a figure of Sonokong), were made using the data obtained form the method.

역공학에서 센서융합에 의한 효율적인 데이터 획득 (Efficient Digitizing in Reverse Engineering By Sensor Fusion)

  • 박영근;고태조;김희술
    • 한국정밀공학회지
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    • 제18권9호
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    • pp.61-70
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    • 2001
  • This paper introduces a new digitization method with sensor fusion for shape measurement in reverse engineering. Digitization can be classified into contact and non-contact type according to the measurement devices. Important thing in digitization is speed and accuracy. The former is excellent in speed and the latter is good for accuracy. Sensor fusion in digitization intends to incorporate the merits of both types so that the system can be automatized. Firstly, non-contact sensor with vision system acquires coarse 3D point data rapidly. This process is needed to identify and loco]ice the object located at unknown position on the table. Secondly, accurate 3D point data can be automatically obtained using scanning probe based on the previously measured coarse 3D point data. In the research, a great number of measuring points of equi-distance were instructed along the line acquired by the vision system. Finally, the digitized 3D point data are approximated to the rational B-spline surface equation, and the free-formed surface information can be transferred to a commercial CAD/CAM system via IGES translation in order to machine the modeled geometric shape.

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