• ETRI Journal
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• v.31 no.5
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• pp.607-609
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• 2009

In this letter, an effective scanning method based on a morphological representation of quantized coefficients is proposed for intra coding in H.264. In the proposed scanning method, the scan order for each block is adaptively reconfigured by exploiting a residual correlation beyond the border of the block. An initial scan order for the current block is determined first by using the pattern of nonzero coefficients in the adjacent block. Then, a complete scan order is obtained by performing the dilation operation at each position within the initial scan order. Experimental results show that the proposed method improves the coding efficiency up to 3.7% compared to the conventional zigzag scanning method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.8
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• pp.74-83
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• 2002

In order to design a huge VLSI system, the scan testing methodology by employing scan flip-flops(cells) is a popular method to test those If chips. In this case, the connection order of scan cells are not important, and hence the order can be determined in the very final stage of physical design such as cell placement. Using this fact, we propose, in this paper, a scan cell reordering method which minimizes the length of wires for scan chain connections. Especially, our reordering method is newly proposed method in the case when the scan cells are grouped according to their clock domains. In fact, the proposed reordering method reduces the wire length about 13.6% more than that by previously proposed reordering method. Our method may also be applicable for reordering scan chains that have various constraints on the scan cell locations due to the chain grouping.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1089-1092
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• 2001

In the stereolithography process, build parameters are laser power, scan velocity, scan width, bean diameter, layer thickness and so on. These values are determined according to product accuracy and build time. Build time can be reduced by improving of scan velocity, laser power, layer thickness, hatching space and so on. But variation of these parameters influence part accuracy, surface roughness, strength. This paper observed cure properties in various beam diameter. In order to examine these, relationships of scan velocity and cure depth, scan velocity and cure width according to various beam diameter in one scan line are measured. And cure thickness is measured according to beam diameter and scan velocity in scan surface of one layer. For reduction of build time, beam diameter and scan velocity is proposed in stereolithography process.

• Investigative Magnetic Resonance Imaging
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• v.11 no.2
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• pp.95-102
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• 2007

Purpose: To acquire high-resolution spiral-scan images at higher magnetic field, high homogeneous magnetic field is needed. Field inhomogeneity mapping and in-vivo shimming are important for rapid imaging such as spiral-scan imaging. The rapid scanning sequences are very susceptible to inhomogeneity. In this paper, we proposed a higher-order shimming method to obtain homogeneous magnetic field. Materials and Methods: To reduce measurement time for field inhomogeneity mapping, simultaneous axial/ sagittal, and coronal acquisitions are done using multi-slice based Fast Spin echo sequence. Acquired field inhomogeneity map is analyzed using the spherical harmonic functions, and shim currents are obtained by the multiplication of the pseudo-inverse of the field pattern with the inhomogeneity map. Results: Since the field inhomogeneity is increasing in proportion to the magnetic field, higher order shimming to reduce the inhomogeneity becomes more important in high field imaging. The shimming technique in which axial, sagittal, and coronal section inhomogeneity maps are obtained in one scan is developed, and the shimming method based on the analysis of spherical harmonics of the imhomogenity map is applied. The proposed technique is applicable to a localized shimming as well. High resolution spiral-scan imaging was successfully obtained with the proposed higher order shimming. Conclusion: Proposed pulse sequence for rapid measurement of inhomogeneity map and higher order shimming based on the inhomogeneity map work very well at 3 Tesla MRI system. With the proposed higher order shimming and localized higher order shimming techniques, high resolution spiral-scan images are successfully obtained at 3 T MRI system.

• Journal of Korea Multimedia Society
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• v.20 no.10
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• pp.1662-1670
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• 2017

A-Scan NDT equipment is widely used in the industrial field because it is inexpensive and easy to carry but it is necessary to have a skilled inspection specialist who is trained to analyze the waveform of ultrasonic signal. Since the welding quality is judged subjectively by the specialist, there is a problem in the reliability of the quality. In the C-Scan NDT which overcomes the shortcomings of the A-Scan, welding part can be represented in the form of two dimensional image by combining one dimensional ultrasonic waveform so that the quality of welding can be grasped without the help of specialist. In order to develop C-Scan NDT, it is necessary to develop an array type two dimensional transducer and an algorithm to composing image by combining ultrasonic signals generated from a two dimensional transducer. In addition, the noise component must be minimized in the ultrasonic signal in order to display the quality of welding in the form of images. Therefore we propose a method to remove noise component from the ultrasonic wave and construct a two dimensional ultrasonic image.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.71-74
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• 2000

The purpose of format conversion is to convert a wide range of personal computer video formats into a target format. Circuits for the conversion have been developed by means of interpolation techniques, such as zero-order interpolation, bilinear interpolation, and bisigmoidal interpolation. This paper proposes a scan converter using cubic splines. The converter was modeled in VHDL on Max+PlusII and implemented with an FPGA chip. The circuit gives much better conversion performance than a scan converter with zero-order or linear interpolation.

• Journal of the Korea Society for Simulation
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• v.9 no.4
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• pp.11-23
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• 2000

The purpose of format conversion is to convert a wide range of personal computer video formats into a target format. Circuits for the conversion have been developed by means of interpolation techniques, such as zero-order interpolation, bilinear interpolation, and bisigmoidal interpolation. This paper proposes a scan converter using cubic splines. The converter was modeled in VHDL, simulated on Max+plus Ⅱ , and implemented with an FPGA chip. The circuit gives much better conversion performance than a scan converter with zero-order or linear interpolation techniques according to simulation results and implementation.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.04a
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• pp.91-95
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• 2000

The purpose of format conversion is to convert a wide range of personal computer video formats to a target format. Circuits for the conversion has been developed by means of interpolation techniques, such as zero-order interpolation, bilinear interpolation, and bisigmoidal interpolation. This paper proposes a scan converter using cubic splines. The converter was modeled in VHDL on Max+Plus II and implemented with an FPGA cpip. The circuit gives much better conversion performance than a scan converter with zero-order or linear interpolation.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.85-95
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• 2010

Purpose: The degradation of an image quality and error of the beam dose calculation can be caused because the metal artifact is generated during the CT simulation of head and neck patient. The usability of the gantry tilt scan for reducing the metal artifact tries to be appraised. Materials and Methods: The inferior $20^{\circ}$ gantry tilt scan was made in order to reduce the metal artifact and $0^{\circ}$ reconstruction image was acquired. The AAPM CT performance Phantom was used in order to compare the CT number of the reconstructed image and Original image. the difference of volume was compared by using the acrylic phantom. The homogeneity of the CT number was evaluated the Intensity volume Histogram (IVH) as in order to evaluate an influence by the metal artifact. A dose was evaluated as the Dose Volume Histogram (DVH). Results: in the comparison of the CT number and volume, the difference showed up less than 0.5%. As to the comparison of IVH, in the gantry tilt scan, influence by an artifact was reduced and the homogeneity of the CT number was improved. The comparison of DVH result reduced the mean dose error of the both sides parotid 0.2~6%. Conclusion: In the Head & Neck radiation therapy, It is difficult and to distinguish tumor and normal tissue and the error of dose is generated by the metal artifact. The delineation of the exact organization was possible if the Gantry tilt scan was used. The CT number homogeneity was improved and the error of dose could be reduced. The Gantry tilt scan confirmed in the Head & Neck radiation therapy to be very useful in the exact radiation therapy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.942-946
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• 2009

A scan order converter has to be placed before the JPEG encoder to provide $8{\times}8$ blocks from the pixels in raster scan order. Recently a hardware architecture has been proposed to implement a scan converter based on the single line memory. Since both read and write accesses happen at each cycle, however, the largest part of the entire power budget is occupied by the SRAM itself. In this paper, the data packing and unpacking procedure is inserted in the processing chain, such that the access frequency to the SRAM is reduced to 1/8 by adopting a packed larger data unit. The simulation results show that the resultant power consumption is reduced down to 16% for the SXGA resolution.