• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.113-124
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• 2008

Distributed operation of overall structural design process, by which product optimization and process parallelization are simultaneously implemented, is presented in this paper. The database-interacted hybrid method, which selectively takes the accustomed procedure of the conventional method in the framework of the optimal design, is utilized here. The staged application of design constraints reduces the computational burden for large complex optimization problems. Two kinds of numeric and graphic processes are simultaneously implemented by concurrent engineering approach in the distributed environment of PC networks. The former is based on finite element optimization method and the latter is represented by AutoCAD using AutoLISP programming language. Numerical computation and database interaction on servers and graphic works on independent clients are communicated through message passing. The numerical experiments for some steel truss models show the validity and usability of the method. This study has sufficient adaptability and expandability, in that it is based on general methodologies and industry standard platforms.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.4
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• pp.15-25
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• 2012

The research on the FPGA CAD tools in academia has been lacking practicality due to the underlying FPGA fabric architecture which is too simple and inefficient to be applied for commercial FPGAs. Recently, the database of placement positions and routing graphs on commercial FPGA architectures has been built, and provided for enabling the academic development of placement and routing tools. To extend the limit of academic CAD tools even further, we have developed the evaluation toolkit for the K-FPGA architecture which is under development. By providing interface for exchanging data with a commercial FPGA toolkit at every step of mapping, packing, placement and routing in the tool chain, the toolkit enables individual tools to be developed without waiting for the results of the preceding step, and with no dependency on the quality of the results, and compared in detail with commercial tools at any step. Also, the fabric primitive library is developed by extracting the prototype from a reporting file of a commercial FPGA, restructuring it, and modeling the behavior of basic gates. This library can be used as the benchmarking target, and a reference design for new FPGA architectures. Since the architecture is described in a standard HDL which is familiar with hardware designers, and read in the tools rather than hard coded, the tools are "data-driven", and tolerable with the architectural changes due to the design space exploration. The experiments confirm that the developed library is correct, and the functional correctness of applications implemented on the FPGA fabric can be validated by simulation. The placement and routing tools are under development. The completion of the toolkit will enable the development of practical FPGA architectures which, in return, will synergically animate the research on optimization CAD tools.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.2
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• pp.101-105
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• 2011

The purpose of this study was to assess the marginal fit of three-unit bridges produced using LAVA CAD/CAM (computer-aided design/computer-aided manufacturing) system and conventional PFG in vitro. Materials and methods: #11, 13 resin teeth were prepared on dentiform, then duplicated. Twenty resin models were fabricated, ten for PFG 3-unit bridges and ten for LAVA 3-unit bridges. Each bridge was cemented on the resin model. Marginal discrepancy was measured with stereoscopic microscope (Nikon DS-Fi 1, Nikon, Japan) at a magnification of ${\times}75$. Independent t-test was done for the statistical analysis. Results: The mean marginal discrepancy values and standard deviations of the PFG bridges was $97.1{\pm}18.7\;{\mu}m$ for incisors, $76.6{\pm}21.8\;{\mu}m$ for canines; that of the LAVA bridges was $90.4{\pm}26.7\;{\mu}m$ for incisor, $110.2{\pm}30.2\;{\mu}m$ for canines. The mean marginal discrepancy between PFG and LAVA for incisor did not show significant difference (P<.05). But for canine, the mean marginal discrepancy of PFG bridges was smaller than that of LAVA bridges (P<.05). Conclusion: The LAVA CAD/CAM 3-unit bridges and the PFG 3-unit bridges showed clinically acceptable marginal discrepancy.

• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.125-137
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• 2018

Simulations have been used to evaluate the efficiency of logistics or manufacturing systems and predict the outcomes of the systems. New simulation models are needed to evaluate new alternative plants and layouts during the resource design process. Although it is easy to handle minor changes in parameters by modifying a simulation model, it takes considerable time and effort for simulation modelers to alter the layout, which involves changes in many simulation sub-models. Therefore, this study proposes a method to transfer information in AutoCAD layout to the simulation model automatically. This study also defines a standard document as an Excel Form, and suggests a method to transfer information on the basic layouts, processes, resources, and workers to a simulation model automatically. A simulation tool, called Tecnomatix Plant Simulation 9.0, was used for this study. The proposed approach in this study was applied to a semiconductor wafer factory for a case study.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.1
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• pp.36-42
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• 2009

We have developed software for converting the volumetric voxel data obtained from X-ray computed tomography(CT) into computer-aided design(CAD) data. The developed software can used for non-destructive testing and evaluation, reverse engineering, and rapid prototyping, etc. The main algorithms employed in the software are image reconstruction, volume rendering, segmentation, and mesh data generation. The feasibility of the developed software is demonstrated with the CT data of human maxilla and mandible bones.

• Progress in Superconductivity
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• v.8 no.1
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• pp.40-45
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• 2006

In emergency rooms, patients with acute chest pain should be diagnosed as quickly as possible with higher diagnostic accuracy for an appropriate therapy to the patients with acute coronary syndrome or for avoiding unnecessary hospital admissions. At present, electrocardiography(ECG) and biochemical markers are generally used to detect myocardial infarction and coronary angiography is used as a gold standard to reveal the degree of narrowing of coronary artery. Magnetocardiography(MCG) has been proposed as a novel and non-invasive diagnostic tool fur the detection of cardiac electrical abnormality associated with myocardial ischemia. In this study, we examined whether the MCG can be used fur the detection of coronary artery disease(CAD) in patients, who were admitted to the emergency room with acute chest pain. MCG was recorded from 36 patients admitted to the emergency room with suspected acute coronary syndrome. The MCG recordings were obtained using a 64-channel SQUID MCG system in a magnetically shielded room. In result, presence of CAD could be found with a sensitivity of 88.2 % in patients with acute chest pain without 57 elevation in ECG, demonstrating a possible use in the emergency room to screen CAD patients.

• Journal of Technologic Dentistry
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• v.40 no.1
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• pp.1-8
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• 2018

Purpose: The purpose of this study is to evaluate the trueness and fitness of machined prostheses according to drill radius setting in CAD software. Methods: For this study, standard abutment were replicated in Type IV stone. The stone abutment were scanned using a dental scanner. The CAD design software was designed using scanned abutment data. When designing, the drill radius was set to 0.3 mm and 0 mm, respectively, and saved. The saved design data was milled using a milling machine (n=13). The inner surface of the milled crown was scanned. The trueness and fitness were measured using the inner scan data of prostheses. Independent t-tests were performed to identify significant differences in each data. Results: Trueness values of the data saved with 0.3 mm and 0 mm drill radius were $18.9{\pm}2.3{\mu}m$ and $19.1{\pm}0.9{\mu}m$, respectively. There was no statistically significant difference between the groups. Fitness values of the data saved with 0.3 mm and 0 mm drill radius were $65.5{\pm}0.8{\mu}m$ and $33.8{\pm}1.0{\mu}m$, respectively. There was a statistically significant difference between the groups (p<.05). Conclusion : Setting the drill radius is important to produce clinically good fit prostheses.

• Journal of Digital Contents Society
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• v.13 no.1
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• pp.31-36
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• 2012

Since the national standard topographic map is made by DXF format which is the results of the National Geographic Information System project and lots of CAD data and scanners can be used to acquire the data easily, the imports of existing DXF file will decrease the costs and time for data acquisition process. In addition, the spatial data such as topographic map should be able to convert to the middle file format such as PostScript in order to be exported into other systems. For this purpose, I design and implement three units of modules, which are File Manipulation Module, MVF Import Module, and MVF Export Module. Finally, I verify the actual transformation of topographic map that are DXF file format by conducting the series of tests.

• Journal of the Korea Furniture Society
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• v.28 no.4
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• pp.371-379
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• 2017

This study established the scope of the main contents and interpretation of wooden product design using the CNC manufacturing technology as well as the basic concepts of which were defined, accordingly. After coming up with the definition of the CNC wood manufacturing technology from the academic point of view, a design study, using the practical CNC manufacturing technology, was conducted by analyzing and summarizing the contents of each process. In addition, data research and analysis including review on literatures and case studies of existing products were promoted besides design development through application of the design concepts, ergonomics, principle of molding, etc. Ultimately, this study suggested the step-by-step procedure in design drawing, 3D modeling, CAD/CAM data production, CNC manufacturing, and prototype completion together with figures. Through this, the study proposed a standard manufacturing guideline for wood product design using digital manufacturing technology. Base on such efforts, the advantages and points for improvement in product design using CNC manufacturing technology and the future direction of development were forwarded. Meanwhile, a prototype image that was developed through collaborative efforts between the academic circle and field workers was presented to help the case study on the wooden product design technique using CNC.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.38-47
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• 2001

This paper decribes the development of computer-aided design of a very precise progressice die for lead frame of semiconductor chip. The approach to the system is based on knowledgr-based rules. Knowledge of fie이 experts. This system has been written in AutoLISP using AutoCAD ona personal computer and the I-DEAS drafting programming Language on the I-DEAS mater series drafting with on HP9000/715(64) workstation. Data exchange between AutoCAD and I-DEAS master series drafting is accomplished using DXF(drawing exchange format) and IGES(initial graphics exchange specification) files. This system is composed of six main modules, which are input and shape treatment, production feasibility check, strip layout, data conversion, die layout, and post processing modules. Based on Knowledge-based rules, the system considers several factors, such as V-notches, dimple, pad chamfer, spank, cavity punch, camber, coined area, cross bow, material and thickness of product, complexities of blank geometry and punch profiles, specifications of available presses, and the availability of standard parts. As forming processes and the die design system using 2D geometry recognition are integrated with the technology of process planning, die design, and CAE analysis, the standardization of die part for lead frames requiting a high precision process is possible. The die layout drawing generated by the die layout module s displayed in graphic form. The developed system makes it possible to design and manufacture lead frame of a semiconductor more efficiently.