• Transactions of Materials Processing
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• v.16 no.4 s.94
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• pp.229-233
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• 2007

The present work focuses on the prediction of birefringence in injection-molded part and its improvement by rapid mold heating. To calculate birefringence, flow-induced residual stress is computed through a fully three-dimensional injection molding analysis. Then the stress-optical law is applied from which the order of birefringence can be evaluated and visualized. The birefringence patterns are predicted for a rectangular plate with a variation of mold temperature, which shows that the amount of molecular orientation and birefringence level decreases with an increase of mold temperature. The effect of mold temperature on the order of birefringence is also studied for a thin-walled rectangular strip, and the relevant results are compared with experimental measurements. Both predicted and experimental patterns of birefringence are in agreements on the observation that the birefringence level diminishes significantly when the mold temperature is raised over the glass transition temperature.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.139-147
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• 1999

Rapid Prototyping has made a drastic change in all industries which needs to reduce the time for the development of new products. Orientation and packing in rapid prototyping is considered as the most important factors to maximize the utilization of space in the build chamber and reduce build time. However, the decision of these parameter is mainly dependant on the operators's experience. This paper presents the methodology to find the optimal build layout considering an orientation and packing of multiple parts in SLS processing. Each part is represented as a voxel structure to deal with the inefficiency in a bounding box approach. Test results show that the adapted BL algorithm with a genetic algorithm(GA) can be applicable to a real industry.

• Laser Solutions
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• v.3 no.1
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• pp.21-28
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• 2000

Selective Laser Sintering (SLS) can produce three-dimensional objects directly from a CAD solid model without part-specific tooling. In this study, a simple rapid prototyping through selective laser sintering on brass powder is investigated using a Nd-YAG laser. Experiments are conducted to produce single lines on a powder-packed bed for various process parameters. Also, temperature distribution in the powder bed and the thickness of a melted line are predicted by finite element analysis. In the numerical analysis, the thermal conductivity of the brass powder which is obtained as a function of state and temperature is used.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.505-513
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• 2014

The RapidEye can acquire the 6.5m spatial resolution satellite imagery with the high temporal resolution on each day, based on its constellation of five satellites. The image products are available in two processing levels of Basic 1B and Ortho 3A. The Basic 1B image have radiometric and sensor corrections and include RPCs (Rational Polynomial Coefficients) data. In Korea, the geometric accuracy of RapidEye imagery can be improved, based on the scaled national digital maps that had been built. In this paper, we present the fully automated procedures to georegister the 1B data using 1:25,000 digital maps. Those layers of map are selected if the layers appear well in the RapidEye image, and then the selected layers are RPCs-projected into the RapidEye 1B space for generating vector images. The automated edge-based matching between the vector image and RapidEye improves the accuracy of RPCs. The experimental results showed the accuracy improvement from 2.8 to 0.8 pixels in RMSE when compared to the maps.

• Journal of Korea Multimedia Society
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• v.16 no.8
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• pp.914-926
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• 2013

Among the recent security systems, security system with fingerprint recognition gets many people's interests through the strengths such as exclusiveness, convenience, etc, in comparison with other security systems. The most important matters for fingerprint recognition system are reliability of matching between the fingerprint in database and user's fingerprint and rapid process of image processing algorithms used for fingerprint recognition. The existing fingerprint recognition system reduces the processing time by removing some processes in the feature extraction algorithms but has weakness of a reliability. This paper realizes the fingerprint recognition algorithm using MAMS(Multi-Access Memory System) for both the rapid processing time and the reliability in feature extraction and matching accuracy. Reliability of this process is verified by the correlation between serial processor's results and MAMS-PP64's results. The performance of the method using MAMS-PP64 is 1.56 times faster than compared serial processor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.775-780
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• 2007

Rapid Prototyping (RP) is a technology that produces prototype parts from 3D computer aided design model data without intermediate processing technology rapidly. CAD model data are created from 3D object digitizing systems but presented just as 2D data when they are printed as a hard copy or displayed on a monitor. However, Rapid Prototyping Technology fabricates 3D objects the same that CAD data because it transforms designed 3D CAD data into 2D cross sectional data, and manufactures layer by layer deposition sequentially. But most of all the small and medium scale companies which produce a toothbrush, a toy and such like provisions are in difficult situations to buy RP system because it is very expensive. In this paper, we propose a 3D control system adopting open source programs for implementing Rapid Prototyping Technology in order that RP system can be purchase at a moderate price.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.165-170
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• 1999

Previous technology of remote sensing was focused on analyzing raster image and gaining information through image processing. But now it has extended to diverse fields like automatic map generation, material exploitation or monitoring environmental changes with effort to utilizing practical usage. And with rapid expansion of information exchange on Internet and high-speed network, the demand of public which want to utilize remotely sensed image has been increased. This makes growth of service on acquisition and processing remotely sensed image. GeoNet is a Java-based remotely sensed image processing system. It is based on Java object-oriented paradigm and features cross-platform, web-based execution and extensibility to client/server remotely sensed image processing model. Remotely sensed image processing software made by Java programming language can suggest alternatives to meet readily demand on remotely sensed image processing in proportion to increase of remotely sensed data. In this paper, we introduce GeoNet and explain its architecture.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.311-314
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• 1995

This paper presents a method for measuring tool wear parameters based on two dimensional image information. The tool wear images were obtained from an ITV camera with magnifying and lighting devices, and were analyzed using image processing techniques such as thresholding, noise filtering and boundary tracing. Thresholding was used to transform the captured gray scale image into a binary image for rapid sequential image processing. The threshold level was determined using a novel technique in which the brightness histograms of two concentric windows containing the tool wear image were compared. The use of noise filtering and boundary tracing to reduce the measuring errors was explored. Performance tests of the measurement precision and processing speed revealed that the direct method was highly effective in intermittent tool wear monitoring.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.93-100
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• 2001

The three dimensional(3D) reconstruction from two dimensional(2D) image data is using in many fields such as RPD(Rapid Product Development) and reverse engineering. In this paper, the main step of 3D reconstruction is comprised of two steps : image processing step and B-spline surface approximation step. In the image processing step, feature points of each cross-section are obtained by means of several image processing technologies. In the B-spline surface approximation step, using the data of feature points obtained in the image processing step, the control points of B-spline surface are obtained, which are used for IGES file of 3D CAD model.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.257-260
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• 2000

In modern battlefield situation, radar and infrared sensors may be located on aircraft having limited computational resources available for real-time computer processing. Hence sensor images are transmitted typically to central stations for processing and automatic target recognition/detection. Owing to the limited bandwidth channels that are typically available between the aircraft and processing stations, images are compressed prior to transmission to facilitate rapid transfer. In this paper we examine the problem of compressing sensor data for transmission, given that target recognition is the end goal. Performance result shows that the front-end target recognition system achieves a relatively high level of performance as well as a high compression ratio.