• 연구논문집
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• 통권25호
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• pp.67-76
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• 1995

A grid generation algorithm associated with turbomachinery cascade flow fields has been developed. The present grid generation system consists of four separate modules. The system input is made of the results of the preliminary design, i.e., flow-path, aerodynamic conditions along the spanwise direction, and the blade profile data. The grid generation method generates a series of two-dimensional grids in the blade-to-blade passage to build up the three-¬dimensional grid, The numerical algorithm adopts the combination of the algebraic and elliptic method to create the internal grids efficiently and quickly. The resultant grids generated from each module of the system are used as the preprocessor for the performance prediction of the turbomachinery blade using Naveir-Stokes method in addition to the blade surface modelling for CAD data. For purposes of illustration, the grid generation system is applied to several complex geometries inculding a turbine rotor with and without a tip flow grid. Application to the blade design of the LP compressor was demonstrated to be very reliable and practical in support of design activities. This customized system are coupled strongly with the design procedure and reduces the man-hours required to predict the aerodynamic performance of the turbomachinery cascades using the CFD technique.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.412-412
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• 2000

This paper presents a task teaching method for off-line programming of a multi-robot system. Teaching commands were developed in order to simplify a complex teaching process, to shorten the setup time for new working environment and to have flexibility for changes in working environment. Four teaching commands can be used to automatically generate trajectories of an end-effector of the robot in electronics assembly line. The robots used in the work cell are a four-axis SCARA robot and six-axis articulated robot. Each robot is controlled in a independent way while objects, working environment and robots are modeled in corresponding modules, respectively. The off- line programming system developed uses OpenGL for a smooth graphic effect in Window s where three dimensional CAD data can be leaded for graphical modeling.

• The Journal of Advanced Prosthodontics
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• 제14권1호
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• pp.22-31
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• 2022

PURPOSE. The purpose of this study was to investigate the misfit and screw preload at the implant abutment connection of implant supported fixed dental prosthesis with cantilever (ICFDP) manufactured using different digital manufacturing techniques and to compare the screw preload before and after cyclic loading. MATERIALS AND METHODS. Mandibular jaw model with four intra-foraminal implants was scanned using digital scanner. Stereolithography file was used to design a framework with nonengaging (NE) abutments and 10 mm cantilever distal to one terminal implant. Five frameworks were constructed using combined digital-conventional techniques (CAD-cast), and five frameworks were constructed using three-dimensional printing (3DP). Additional CAD-cast framework was constructed in a way that ensures passive fit (PF) to use as control. Scanning electron microscope (SEM) measured the implant abutment connection misfit. Sixty screws were used on the corresponding frameworks. Screws were torqued and pre-cyclic loading reverse torque value (RTV) was recorded. Frameworks were subjected to 200,000 loading cycles with a loading point 9 mm from the center of terminal implants adjacent to the cantilever and post-cyclic loading RTVs were recorded. RESULTS. Microscopic readings showed significant differences between frameworks. PF demonstrated the lowest measurements of 16.04 (2.6) ㎛ while CAD-cast demonstrated the highest measurements of 29.2 (3.1) ㎛. In all groups, RTVs were significantly lower than the applied torque. Post-cyclic loading RTV was significantly lower than pre-cyclic loading RTV in PF and 3DP frameworks. Differences in RTVs between the three manufacturing techniques were insignificant. CONCLUSION. Although CAD-cast and three-dimensionally printed (3DP) both produce frameworks with clinically acceptable misfit, 3DP might not be the technique of choice for maintaining screw's preload stability under an aggressive loading situation.

• 한국염색가공학회지
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• 제18권1호
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• pp.33-43
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• 2006

The purpose of this study was to eximine the effect of different yam twisting methods on mechanical properties and 3D CAD images of plain knitted fabrics made of composite yarns. Six yams were used in this study: four different composite yams of the six consist of acetate and functional polyester (Poly-m) with the ratio of 70:30, and the rest two are the original acetate $100\%$ yam and the poly-m $100\%$ yarn. The four kinds of composite yarns were processed in combinations of twisting processes such as interlacing, false twisting, two for one twisting, combined twisting and single covering, and the two original yams were knitted without any twisting process. Sixteen mechanical properties of all the six knitted fabrics, knitted under the same knitting conditions, were measured by KES-FB system with the outer knit condition. The results were as follows; 1) When the sample applied with the false twisting process at the temperature as high as $220^{\circ}C$, ENT, B, HB, G and RC values of samples increased which leads to increasing dimensional stability. 2) To gain the high bending and shear properties in the single covering process, selecting the core yarn with such properties is the most important factor. 3) Interlacing process effected to increase RC value. 4) False twisting process after interlacing process gave bulkiness and un-interlaced part in yam was increased SMD value. The SMD value of the kilted fabric of the composite yarn, which was put through the combined twist process, was higher than those of which simple process such as the two for one twist or the single covering process applied. In order to achieve the silk-like surface feel of knitted fabric, the sin91e covering process is recommended. 5) Examining the simulation images of the knifed fabrics of composite yarn, which were generated by the 3D CAD system based on the mechanical properties of the fabric, led that appearance could be changed as different twisting methods were applied.

• 한국치위생학회지
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• 제22권6호
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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.

• The Journal of Advanced Prosthodontics
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• 제12권3호
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• pp.124-130
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• 2020

PURPOSE. The aim of this in vitro study was to evaluate the effect of sintering procedures on marginal discrepancies of fixed partial metal frameworks fabricated using different sintering-based computer-aided design and computer/aided manufacturing (CAD/CAM) techniques. MATERIALS AND METHODS. Forty resin die models of prepared premolar and molar abutment teeth were fabricated using a three-dimensional (3D) printer and divided into four groups (n = 10) according to the fabrication method of metal frameworks used: HM (via hard milling), SM (via soft metal milling), L25 (via direct metal laser melting [DMLM] with a 25 ㎛ layer thickness), and L50 (via direct DMLM with a 50 ㎛ layer thickness). After the metal frameworks were fabricated and cemented, five vertical marginal discrepancy measurements were recorded in each site (i.e., buccal, facing the pontic, lingual, and facing away from the pontic) of both abutment teeth under a stereomicroscope (×40). Data were statistically analyzed at a significance level of 0.05. RESULTS. No statistically significant differences (P>.05) were found among the four axial sites of metal frameworks fabricated by sintering-based CAD/CAM techniques. The HM and L25 groups showed significantly (P<.001) lower marginal discrepancy values than the SM and L50 groups. CONCLUSION. Marginal discrepancy in the sites facing the pontic was not influenced by the type of sintering procedure. All fabrication methods exhibited clinically acceptable results in terms of marginal discrepancies.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.119-122
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• 2007

The purpose of this study is to propose development of Schedule based Architectural Construction Simulation System. In this study (or paper), It analyzes the simulation system concept and its characteristics, and analyze the main functions simulation system and the range of functions which are already used currently. Therefore, It could find the limit of the present simulation system, and propose more effective solutions to develop Schedule based Architectural Construction Simulation System.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.353-356
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• 2007

The purpose of this study is to propose development of Schedule based Architectural Construction Simulation System. In this study (or paper), we analysis the simulation system concept ant) its characteristics, and analyze the main functions simulation system and the range of functions which are already used currently. Therefore, we could find the limit of the present simulation system. and propose more effective solutions to develop Schedule based Architectural Construction Simulation System.

• International Journal of CAD/CAM
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• 제11권1호
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• pp.11-17
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• 2011

A new method has been developed in this paper for automatic quadrilateral mesh generation for a two-dimensional domain. The method is named 'centering method' because it centers a point at the domain and then divides it into sub-domains using cutting lines from the center point. Each of the cutting lines is selected based on the criterion using the angles between the boundary of the domain and the cutting line. The decomposition of the domain into sub-domains is repeated until every subdomain has four or six nodes. Pre-defined splitters are used to divide six-node domains into quadrilateral elements depending on their configuration and presence on the boundary of the initial domain. Arbitrary domains are meshed as examples to verify the robustness of the new method.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.328-334
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• 2018

PURPOSE. To evaluate the reproducibility of scan-based abutments using a blue light model scanner. MATERIALS AND METHODS. A wax cast abutment die was fabricated, and a silicone impression was prepared using a silicone material. Nine study dies were constructed using the prepared duplicable silicone, and the first was used as a reference. These dies were classified into three groups and scanned using a blue light model scanner. The first three-dimensional (3D) data set was obtained by scanning eight dies separately in the first group. The second 3D data set was acquired when four dies were placed together in the scanner and scanned twice in the second group. Finally, the third 3D data set was obtained when eight dies were placed together in the scanner and scanned once. These data were then used to define the data value using third-dimension software. All the data were then analyzed using the non-parametric Kruskal-Wallis H test (${\alpha}=.05$) and the post-hoc Mann-Whitney U-test with Bonferroni's correction (${\alpha}=.017$). RESULTS. The means and standard deviations of the eight dies together were larger than those of the four dies together and of the individual die. Moreover, significant differences were observed among the three groups (P<.05). CONCLUSION. With larger numbers of abutments scanned together, the scan becomes more inaccurate and loses reproducibility. Therefore, scans of smaller numbers of abutments are recommended to ensure better results.